@article {23411,
	title = {Side-on End-on Bound Dinitrogen: An Activated Bonding Mode That Facilitates Functionalizing Molecular Nitrogen},
	journal = {Accounts of Chemical Research},
	volume = {42},
	year = {2009},
	month = {Jan},
	pages = {127-133},
	type = {Review},
	abstract = {<p>Molecular nitrogen is the source of all of the nitrogen necessary to sustain life on this planet. How it is incorporated into the biosphere is complicated by its intrinsic inertness. For example, biological nitrogen fixation takes N-2 and converts it into ammonia using various nitrogenase enzymes, whereas industrial nitrogen fixation converts N-2 and H-2 to NH3 using heterogeneous iron or ruthenium surfaces. In both cases, the processes are energy-intensive. Is it possible to discover a homogeneous catalyst that can convert molecular nitrogen into higher-value organonitrogen compounds using a less energy-intensive pathway? If this could be achieved, it would be considered a major breakthrough in this area. In contrast to carbon monoxide, which is reactive and an important feedstock in many homogeneous catalytic reactions, the ischelectronic but inert N-2 molecule is a very poor ligand and not a common industrial feedstock, except for the above-mentioned industrial production of NH3. Because N-2 is readily available from the atmosphere and because nitrogen is an essential element for the biosphere, attempts to discover new processes involving this simple small molecule have occupied chemists for over a century. Since the first discovery of a dinitrogen complex in 1965, inorganic chemists have been key players in this area and have contributed much fundamental knowledge on structures, binding modes, and reactivity patterns. For the most part, the synthesis of dinitrogen complexes relies on the use of reducing agents to generate an electron-rich intermediate that can interact with this rather inert molecule. In this Account, a facile reaction of dinitrogen with a ditantalum tetrahydride species to generate the unusual side-on end-on bound N-2 moiety is described. This particular process is one of a growing number of new, milder ways to generate dinitrogen complexes. Furthermore, the resulting dinitrogen complex undergoes a number of reactions that expand the known patterns of reactivity for coordinated N-2. This Account reviews the reactions of ([NPN]Ta)(2)(mu-H)(2)(mu-eta(1):eta(2)-N-2), 2 (where NPN = PhP(CH2SiMe2NPh)(2)), with a variety of simple hydride reagents, E-H (where E-H = R2BH, R2AlH, RSiH3, and Cp2ZrCl(H)), each of which results in the cleavage of the N-N bond to form various functionalized imide and nitride moieties. This work is described in the context of a possible catalytic cycle that in principle could generate higher-value nitrogen-containing materials and regenerate the starting ditantalum tetrahydride. How this fails for each particular reagent is discussed and evaluated.</p>},
	keywords = {ammonia, CLEAVAGE, CONVERSION, COORDINATED N-2 LIGAND, H-2, HYDROSILYLATION, MOLYBDENUM, REACTIVITY, REDUCTION, TANTALUM COMPLEX},
	isbn = {0001-4842},
	author = {Fryzuk, MD}
}
@article {2285,
	title = {Probing General Base Catalysis in the Hammerhead Ribozyme},
	journal = {Journal of the American Chemical Society},
	volume = {130},
	number = {46},
	year = {2008},
	note = {ISI Document Delivery No.: 406QZTimes Cited: 8Cited Reference Count: 53Thomas, Jason M. Perrin, David M.},
	month = {Nov},
	pages = {15467-15475},
	type = {Article},
	abstract = {Recent structural and computational studies have shed new light on the catalytic mechanism and active site structure of the RNA cleaving hammerhead ribozyme. Consequently, specific ribozyme functional groups have been hypothesized to be directly involved in general/acid base catalysis. In order to test this hypothesis, we have developed an affinity label to identify the functional general base in the S. mansoni hammerhead ribozyme. The ribozyme was reacted with a substrate analogue bearing a 2{\textquoteright}-bromoacetamide group in place of the nucleophilic 2{\textquoteright}-hydroxyl group which would normally be deprotonated by a general base. The electrophilic 2{\textquoteright}-bromoacetamide group is poised to alkylate the general base, which is subsequently identified by footprinting analysis. Herein, we demonstrate alkylation of N1 of G12 in the hammerhead ribozyme in a pH and [Mg2+] dependent manner that is consistent with the native cleavage reaction. These results provide substantial evidence that deprotonated N1 of G12 functions directly as a general base in the hammerhead ribozyme; moreover, our experiments provide evidence that the pK(a) of G12 is perturbed downward in the context of the active site structure. We also observed other pH-independent alkylations, which do not appear to reflect the catalytic mechanism, but offer further insight into ribozyme conformation and structure.},
	keywords = {ACTIVE-SITE, CLEAVAGE, CRYSTAL-STRUCTURE, DELTA VIRUS RIBOZYME, HAIRPIN RIBOZYME, MECHANISM, METAL-ION, MONOVALENT CATIONS, NUCLEOBASE CATALYSIS, RNA},
	isbn = {0002-7863},
	url = {<Go to ISI>://000263311300051},
	author = {Thomas, J. M. and Perrin,David M.}
}
@article {1573,
	title = {Inner-sphere two-electron reduction leads to cleavage and functionalization of coordinated dinitrogen},
	journal = {Proceedings of the National Academy of Sciences of the United States of America},
	volume = {103},
	number = {46},
	year = {2006},
	note = {ISI Document Delivery No.: 108OPTimes Cited: 14Cited Reference Count: 55Spencer, Liam P. MacKay, Bruce A. Patrick, Brian O. Fryzuk, Michael D.},
	month = {Nov},
	pages = {17094-17098},
	type = {Article},
	abstract = {Activation of molecular nitrogen by transition metal complexes is an area of current interest as investigations using the inert N-2 molecule to produce higher-value organonitrogen compounds intensify. In an attempt to extend the addition of hydride reagents E-H (where E = BR2, AIR(2), and SiR3) to the dinitrogen complex ([NPN]Ta)(2)(mu-H)(2)(mu-eta(2):eta(2)-N-2) [1; where NPN = (PhNSiMe2CH2)(2)PPh], the reaction with zirconocene chlorohydride, [Cp2Zr(Cl)H](x), was examined. The crystalline product formed in 35\% yield was determined to be ([NP(N)N]Ta)(mu-H)(2)(mu-N)(Ta[NPN])(ZrCP2) (2) in which the coordinated N-2 has been cleaved to form a phosphinimide bridging between Ta and Zr and a triply bridging nitride. The mechanism of this reaction was examined to determine the fate of the chloride and hydricle ligands attached to Zr in the starting zirconocene reagent. Using the zirconocene dihydride dimer ([Cp2ZrH2](2)), a higher yield of 2 was obtained (76\%), and H-2 was also observed by H-1 NMR spectroscopy. To probe the origin of the eliminated H-2, the dideuterated dinitrogen complex ([NPN]Ta)(2)(tLID)(2)(mu-eta(1):n(2)-N-2) (d(2)-1) was allowed to react with ([CP2ZrH2](2)), which resulted in the formation of ([NP(N)N]Ta)(mu-D)(2)(mu-N)(Ta[NPN]) (ZrCP2), (d(2)-2), with no evidence of hydrogen for deuterium scrambling between the starting zirconocene dihydride and the ditantalum dinitrogen complex. Studies into the use of preformed Zr(II) and Ti(II) reagents were also performed. The proposed mechanism involves initial adduct formation that facilitates inner-sphere electron transfer to cleave the N-N bond to form a species with bridging nitrides, one of which is transformed by nucleophilic attack of a phosphine donor to generate the observed phosphinimide.},
	keywords = {BOND-CLEAVAGE, BRIDGING N-2 UNIT, CLEAVAGE, COMPLEXES, dinitrogen coordination, END-ON, METAL-COMPLEXES, MOLECULAR, MOLYBDENUM-IRON PROTEIN, NITROGEN, nitrogen fixation, nitrogen-nitrogen bond, PHOSPHINIMIDE COMPLEXES, SIDE-ON, TANTALUM COMPLEX, TUNGSTEN},
	isbn = {0027-8424},
	url = {<Go to ISI>://000242249400008},
	author = {Spencer, L. P. and MacKay, B. A. and Patrick, B. O. and Fryzuk,Michael D.}
}
@article {1605,
	title = {Ortho-selective C-Hactivation of substituted benzenes effected by a tungsten alkylidene complex without substituent coordination},
	journal = {Organometallics},
	volume = {25},
	number = {17},
	year = {2006},
	note = {ISI Document Delivery No.: 070PZTimes Cited: 13Cited Reference Count: 36Tsang, Jenkins Y. K. Buschhaus, Miriam S. A. Legzdins, Peter Patrick, Brian O.},
	month = {Aug},
	pages = {4215-4225},
	type = {Article},
	abstract = {{Gentle thermolysis of the bis(neopentyl) complex Cp*W(NO)(CH2CMe3)(2) (1) at 70 degrees C in various substituted benzenes results in the loss of neopentane and the generation of the transient alkylidene complex Cp*W(NO)(=CHCMe3) (A), which subsequently effects single C-H bond activations of the benzenes. These activations exhibit a pronounced selectivity for the C-H linkages ortho to the benzene substituents. Thus, thermal reactions of 1 with C6H5X lead to the preferential formation of the corresponding Cp*W( NO)(CH2CMe3)(o-C6H4X) complexes, the ortho-selectivity, i. e.},
	keywords = {CLEAVAGE, CRYSTAL-STRUCTURE, ELIMINATION, H BONDS, IRIDIUM, MECHANISM, METAL-COMPLEXES, {ARYL},
	isbn = {0276-7333},
	url = {<Go to ISI>://000239536800028},
	author = {Tsang, J. Y. K. and Buschhaus, M. S. A. and Legzdins,Peter and Patrick, B. O.}
}
@article {1212,
	title = {Formation of phosphorus-nitrogen bonds by reduction of a titanium phosphine complex under molecular nitrogen},
	journal = {Journal of the American Chemical Society},
	volume = {127},
	number = {37},
	year = {2005},
	note = {ISI Document Delivery No.: 965CYTimes Cited: 27Cited Reference Count: 22},
	month = {Sep},
	pages = {12796-12797},
	type = {Article},
	keywords = {ATOMS, CHEMISTRY, CLEAVAGE, COORDINATION, DINITROGEN ACTIVATION, LIGAND, NIOBIUM, ZIRCONIUM},
	isbn = {0002-7863},
	url = {<Go to ISI>://000231928800024},
	author = {Morello, L. and Yu, P. H. and Carmichael, C. D. and Patrick, B. O. and Fryzuk,Michael D.}
}
@article {1270,
	title = {Lewis adducts of the side-on end-on dinitrogen-bridged complex [{(NPN)Ta}(2)(mu-H)(2)(mu-eta(1):eta(2)-N-2)] with AlMe3, GaMe3, and B(C6F5)(3): Synthesis, structure, and spectroscopic properties},
	journal = {Chemistry-a European Journal},
	volume = {11},
	number = {2},
	year = {2005},
	note = {ISI Document Delivery No.: 887VLTimes Cited: 12Cited Reference Count: 49},
	month = {Jan},
	pages = {604-618},
	type = {Article},
	abstract = {{Reaction of the side-on end-on dinitrogen complex [{(NPN)Ta}(2)(mu- H)(2)(mu-eta(1):eta(2)-N-2)] (1; in which NPN= (PhNSiMe2CH2)(2)PPh), with the Lewis acids XR3 results in the adducts [{(NPN)Ta}(2)(mu-H)(2)(mu-eta(1):eta(2)-NNXR3)]},
	keywords = {CHEMISTRY, CLEAVAGE, COORDINATED, density functional calculations, DINITROGEN, DINITROGEN COMPLEXES, DINUCLEAR TANTALUM COMPLEX, EFFECTIVE CORE POTENTIALS, FIXATION, MOLECULAR CALCULATIONS, MOLYBDENUM CENTER, N-2 LIGAND, NITROGEN, Raman spectroscopy, REACTIVITY, tantalum, TRIS(PENTAFLUOROPHENYL)BORANE},
	isbn = {0947-6539},
	url = {<Go to ISI>://000226333500014},
	author = {Studt, F. and MacKay, B. A. and Johnson, S. A. and Patrick, B. O. and Fryzuk,Michael D. and Tuczek, F.}
}
@article {1187,
	title = {A new arene-bridged diamidophosphine ligand and its coordination chemistry with zirconium(IV)},
	journal = {Organometallics},
	volume = {24},
	number = {6},
	year = {2005},
	note = {ISI Document Delivery No.: 904YFTimes Cited: 15Cited Reference Count: 48},
	month = {Mar},
	pages = {1112-1118},
	type = {Article},
	abstract = {The arene-bridged dilithium diamidophosphine ligand, [(2,4,6-Me3C6H2)NLi-2-(5-MeC6H3)](2)PPh, [NPN]*Li-2, was prepared from (2,4,6-Me3C6H2)(2-Br-4-MeC6H3)NH, (BuLi)-Bu-n, and PhPCl2 in Et2O and isolated as a dioxane adduct in similar to 85\% yield. The solid-state structure of [NPN]*Li-2(THF)2 as determined by X-ray diffraction shows both lithiums bridged by the amido nitrogens with one Li ion coordinated to the phosphine donor. The reaction of [NPN]*H-2 and Zr(NMe2)(4) in toluene produced [NPN]*Zr(NMe2)(2) in 90\% isolated yield. Addition of excess Me3SiCl to [NPN]*Zr(NMe2)(2) converts it to [NPN]*ZrCl2 in high yield. The solid-state structure of [NPN] *ZrCl2 as determined by X-ray diffraction shows the Zr center is a distorted trigonal bipyramid with the phosphine and the chloride apical. The ortho-Me{\textquoteright}s on the N-mesityl moiety are inequivalent in both the Li and Zr complexes of [NPN]* by NMR spectroscopy, while in [NPN]*H-2 MesN ortho-Me{\textquoteright}s appear as broad singlets. VT-NMR of [NPN]*H-2 indicated that Delta G(rot)(double dagger) of MesC(ipso)-N is approximately 15.5 +/- 0.3 kcal mol(-1). The thermally labile and light-sensitive zirconium dimethyl complex [NPN]*ZrMe2 was prepared from [NPN]*ZrCl2 and MeMgCl in Et2O in 80\% yield.},
	keywords = {CLEAVAGE, COMPLEX, COUPLING REACTIONS, DINITROGEN LIGAND, END-ON, METAL-COMPLEXES, MOLECULAR NITROGEN, N-2 UNIT, palladium, SIDE-ON, tantalum},
	isbn = {0276-7333},
	url = {<Go to ISI>://000227533800014},
	author = {MacLachlan, E. A. and Fryzuk,Michael D.}
}
@article {1250,
	title = {Phosphine-induced ancillary ligand orthometalation at a tantalum-tantalum double bond},
	journal = {Organometallics},
	volume = {24},
	number = {11},
	year = {2005},
	note = {ISI Document Delivery No.: 927XMTimes Cited: 0Cited Reference Count: 32},
	month = {May},
	pages = {2606-2611},
	type = {Article},
	abstract = {The dinuclear tantalum tetrahydride complexes ((RPh)[NPN]Ta)(2)(mu-H)(4) ([NPN] = (PhNSiMe2CH2)(2)PR; R = Ph, Cy) promote the asymmetric activation of molecular nitrogen to form ((RPh)[NPN]Ta)(2)(mu-eta(1):eta(2)-N-2)(mu-H)(2). The coordinatively unsaturated dinuclear dihydride, ((RPh)[NPN]Ta)(2)(mu-H)(2), has been proposed as the reactive intermediate, with a tantalum-tantalum double bond storing four electrons with which to reduce N-2. Efforts to trap ((CyPh)[NPN]Ta)(2)(mu-H)(2) with excess PMe3 at low temperatures promoted the formation of a green product, proposed to be (CyPh [NPN]Ta(PMe3))(2)(mu-H)(2). Attempts to isolate this product promoted the orthometalation of an ancillary ligand N-Ph ring, forming (CyPh)[NPN]Ta(mu-H)(2)[mu-N(C6H4)]Ta[PN](H)(PMe3). Addition of 1 equiv of PMe3 to ((PhPh)[NPN] Ta)(2)(mu-H)(4) immediately produced the analogous orthometalation derivative, [NPN]Ta(mu-H)(2)[mu-N(C6H4)]Ta[PN](H)(PMe3).},
	keywords = {BRIDGING N-2 UNIT, C-H ACTIVATION, CLEAVAGE, CRYSTAL-STRUCTURE, DINITROGEN LIGAND, DINUCLEAR, EARLY TRANSITION-METALS, END-ON, ORGANODIMETALLIC COMPLEXES, SIDE-ON},
	isbn = {0276-7333},
	url = {<Go to ISI>://000229233800011},
	author = {Shaver, M. P. and Fryzuk,Michael D.}
}
@article {1190,
	title = {Rhodium(III)-cyclometalated-imine complexes: Solution behavior and reactivity with molecular hydrogen},
	journal = {Organometallics},
	volume = {24},
	number = {7},
	year = {2005},
	note = {ISI Document Delivery No.: 909LJTimes Cited: 16Cited Reference Count: 41},
	month = {Mar},
	pages = {1445-1451},
	type = {Article},
	abstract = {Acetone solutions of cis, trans, cis-[Rh(H)(2)(PPh3)(2)(acetone)(2)] PF6 and cis-[Rh(PPh3)(2)(acetone)(2)]PF6 react with the imines RN=CR {\textquoteright}(R {\textquoteright}{\textquoteright}), where R = PhCH2, Ph, or C6H11; R {\textquoteright}= H or Me; and R {\textquoteright}{\textquoteright} = Ph or P-OMe-C6H4, to form orthometalated complexes exemplified by [Rh(H){RN= CR {\textquoteright}(o-C6H4)}(PPh3)(2)(acetone)]PF6 that are generally characterized spectroscopically, and in one case (where R = PhCH2, R {\textquoteright} = Me, and R {\textquoteright}{\textquoteright} = p-OMe-C6H4) by X-ray crystallography. These complexes maintain their integrity in acetone solution and show no reaction toward 1 atm H-2 at ambient conditions. In MeOH, the complexes in which R {\textquoteright} = Me simply change to the corresponding MeOH derivative, but when R {\textquoteright} = H they are partially converted to the non-orthometalated, eta(1)-N-imine species [Rh(PPh3)(2)(RN=CHR {\textquoteright}{\textquoteright})(MeOH)]PF6 (I), and in MeOH, stoichiometric hydrogenation of the imine to the corresponding amine occurs via I. We have shown recently (Inorg. Chem. 2004, 43, 4820) that the catalyzed hydrogenation of PhCH2N=C(H)Ph to dibenzylamine using cis, trans, cis- [Rh(H)(2)(PPh3)(2)(MeOH)(2)] PF6 as catalyst precursor in MeOH proceeds via a cationic Rh-(eta(1)-N-imine)(amine) intermediate (II), analogous to I but with the MeOH replaced by the amine that is formed via hydrolysis of the imine by the presence of adventitious water. Intermediate I (R = PhCH2, R {\textquoteright}{\textquoteright} = Ph) is shown to be somewhat less active than II toward H-2, but both intermediates provide viable pathways for hydrogenation of the imine. The orthometalated imine-amine complex [Rh(H){PhCH2N=C(Me)(o-C6H4)}(PPh3)(2)(NH2CH2Ph)]PF6, where the benzylamine comes from imine hydrolysis, is also isolated and characterized crystallographically.},
	keywords = {ACTIVATION, AZO, C-H BONDS, CATIONIC, CLEAVAGE, COMPLEXES, CRYSTAL, LIGANDS, METAL-IMINE COMPOUNDS, RHODIUM(III) COMPLEXES},
	isbn = {0276-7333},
	url = {<Go to ISI>://000227861100013},
	author = {Marcazzan, P. and Patrick, B. O. and James, Brian R.}
}
@article {994,
	title = {Spectroscopic properties and quantum chemistry-based normal coordinate analysis (QCB-NCA) of a dinuclear tantalum complex exhibiting the novel side-on end-on bridging geometry of N-2: Correlations to electronic structure and reactivity},
	journal = {Journal of the American Chemical Society},
	volume = {126},
	number = {1},
	year = {2004},
	note = {ISI Document Delivery No.: 761ZMTimes Cited: 16Cited Reference Count: 40},
	month = {Jan},
	pages = {280-290},
	type = {Article},
	abstract = {The vibrational properties and the electronic structure of the side-on end-on N-2-bridged Ta complex ([NPN]Ta(mu-H))(2)(mu-eta(1):eta(2)-N-2) (1) (where [NPN] = (PhNSiMe2CH2)(2)PPh) are analyzed. Vibrational characterization of the Ta-2(mu-N-2)(mu-H)(2) core is based on resonance Raman and infrared spectroscopies evaluated with a novel quantum chemistry-based normal coordinate analysis (QCB-NCA). The N-N stretching frequency is found at 1165 cm(-1) exhibiting a N-15(2) isotope shift of -37 cm(-1). Four other modes of the Ta2N2H2 core are observed between 430 and 660 cm(-1). Two vibrations of the bridging hydrido ligands are also identified in the spectra. On the basis of experimental frequencies and the QCB-NCA procedure, the N-N force constant is determined to be 2.430 mdyn -Angstrom(-1). The Ta-N force constants are calculated to be 2.517 mdyn Angstrom(-1) for the Ta-eta(1)-N-2 bond and 1.291 and 0.917 mdyn Angstrom(-1) for the Ta-eta(2)-N-2 bonds, respectively. DFT calculations on 1 suggest that the bridging dinitrogen ligand carries a charge of -1.1, which is equally distributed over the two nitrogen atoms. However, orbital analysis reveals that the terminal nitrogen makes lower contributions to the pi orbitals and much higher contributions to the pi* orbitals of the N-2 ligand than the bridging nitrogen. This suggests that reactions of the dinitrogen ligand with electrophiles should preferentially occur at the terminal N atom, in agreement with experimental results.},
	keywords = {ACTIVATION, CLEAVAGE, DINITROGEN FIXATION, EFFECTIVE CORE POTENTIALS, FUNCTIONALIZATION, LIGAND, MOLECULAR CALCULATIONS, MOLYBDENUM, NITROGEN-FIXATION, REDUCTION PATHWAY},
	isbn = {0002-7863},
	url = {<Go to ISI>://000187945400064},
	author = {Studt, F. and MacKay, B. A. and Fryzuk,Michael D. and Tuczek, F.}
}
@article {617,
	title = {Dinuclear organometallic dinitrogen complexes of niobium},
	journal = {Inorganica Chimica Acta},
	volume = {345},
	year = {2003},
	note = {ISI Document Delivery No.: 653EUTimes Cited: 4Cited Reference Count: 30},
	month = {Mar},
	pages = {53-62},
	type = {Article},
	abstract = {{The niobium(III) chloride precursors (R)[P2N2]NbCl stabilized by the bis-(amidophosphine) macrocycle (where (R)[P2N2] RP(CH2SiMe2NSiMe2CH2)(2)PR},
	keywords = {ACTIVATION, amidophosphine ligands, AZOBENZENE, CLEAVAGE, CRYSTAL-STRUCTURE, CRYSTALLOGRAPHY, DINITROGEN COMPLEXES, END-ON, FIXATION, fluxionality, macrocycle, macrocycles, N-2, NIOBIUM, NITRIDE, SIDE-ON},
	isbn = {0020-1693},
	url = {<Go to ISI>://000181422900008},
	author = {Fryzuk,Michael D. and Kozak, C. M. and Patrick, B. O.}
}
@article {429,
	title = {Incorporation of 8-histaminyldeoxyadenosine [8-(2-(4-imidazolyl)ethylamino)-2 {\textquoteright}-deoxyriboadenosine] into oligodeoxyribonucleotides by solid phase phosphoramidite coupling},
	journal = {Nucleosides Nucleotides \& Nucleic Acids},
	volume = {21},
	number = {10},
	year = {2002},
	note = {ISI Document Delivery No.: 622CATimes Cited: 5Cited Reference Count: 37},
	pages = {651-664},
	type = {Article},
	abstract = {The 3{\textquoteright} phosphoramidite of 8-histaminyl deoxyadenosine has been prepared and successfully incorporated into a short oligodeoxyribonucleotide. The synthetic methodology leading to this preparation is given and the implications for developing new DNAzymes as well as probing unusual nucleic acid structures are discussed.},
	keywords = {BEARING IMIDAZOLE, CATALYTIC REPERTOIRE, CLEAVAGE, DERIVATIVES, DNA, IMIDAZOLYL FUNCTIONALITIES, NUCLEIC-ACIDS, OLIGONUCLEOTIDES, RIBONUCLEASES, RNA},
	isbn = {1525-7770},
	url = {<Go to ISI>://000179627900003},
	author = {Lermer, L. and Hobbs, J. and Perrin,David M.}
}
@article {5161,
	title = {Bridging the gap between proteins and nucleic acids: A metal-independent RNAseA mimic with two protein-like functionalities},
	journal = {Journal of the American Chemical Society},
	volume = {123},
	number = {8},
	year = {2001},
	note = {ISI Document Delivery No.: 405LXTimes Cited: 74Cited Reference Count: 49},
	month = {Feb},
	pages = {1556-1563},
	type = {Article},
	abstract = {Two synthetically modified nucleoside triphosphate analogues (adenosine modified with an imidazole and uridine modified with a cationic amine) are enzymatically polymerized in tandem along a degenerate DNA library for the combinatorial selection of an RNAse A mimic. The selected activity is consistent with both electrostatic and general acid/base catalysis at physiological pH in the absence of divalent metal cations. The simultaneous use of two modified nucleotides to enrich the catalytic repertoire of DNA-based catalysts has never before been demonstrated and evidence of general acid/base catalysis at pH 7.4 for a DNAzyme has never been previously observed in the absence of a divalent metal cation or added cofactor, This work illustrates how the incorporation of protein-like functionalities in nucleic acids can bridge the gap between proteins and oligonucleotides underscoring the potential for using nucleic acid scaffolds in the development of new materials and improved catalysts for use in chemistry and medicine.},
	keywords = {5{\textquoteright}-TRIPHOSPHATES, ADENOSINE, ANALOG, CATALYSIS, CLEAVAGE, CLEAVING DNA ENZYME, DERIVATIVES, IN-VITRO SELECTION, PHOSPHORYL-TRANSFER-REACTIONS, PORPHYRIN METALATION, TRANSITION-STATE},
	isbn = {0002-7863},
	url = {<Go to ISI>://000167162100002},
	author = {Perrin,David M. and Garestier, T. and Helene, C.}
}
@article {5183,
	title = {Catalysis and binding in L-ribulose-5-phosphate 4-epimerase: A comparison with L-fuculose-1-phosphate aldolase},
	journal = {Biochemistry},
	volume = {40},
	number = {49},
	year = {2001},
	note = {ISI Document Delivery No.: 500CJTimes Cited: 15Cited Reference Count: 15},
	month = {Dec},
	pages = {14772-14780},
	type = {Article},
	abstract = {L-Ribulose-5-phosphate (L-Ru5P) 4-epimerase and L-fuculose-1-phosphate (L-Fuc1P) aldolase are evolutionarily related enzymes that display 26\% sequence identity and a very high degree of structural similarity. They both employ a divalent cation in the formation and stabilization of an enolate during catalysis, and both are able to deprotonate the C-4 hydroxyl group of a phosphoketose substrate. Despite these many similarities, subtle distinctions must be present which allow the enzymes to catalyze two seemingly different reactions and to accommodate substrates differing greatly in the position of the phosphate (C-5 vs C-1). Asp76 of the epimerase corresponds to the key catalytic acid/base residue Glu73 of the aldolase. The D76N mutant of the epimerase retained considerable activity, indicating it is not a key catalytic residue in this enzyme. In addition, the D76E mutant did not show enhanced levels of background aldolase activity. Mutations of residues in the putative phosphate-binding pocket of the epimerase (N28A and K42M) showed dramatically higher values of K-M for L-Ru5P. This indicates that both enzymes utilize the same phosphate recognition pocket, and since the phosphates are positioned at opposite ends of the respective substrates, the two enzymes must bind their substrates in a reversed or "flipped" orientation. The epimerase mutant D120N displays a 3000-fold decrease in the value of k(cat), suggesting that Asp 120{\textquoteright} provides a key catalytic acid/base residue in this enzyme. Analysis of the D120N mutant by X-ray crystallography shows that its structure is indistinguishable from that of the wild-type enzyme and that the decrease in activity was not simply due to a structural perturbation of the active site. Previous work [Lee, L.V., Poyner, R.R., Vu, M.V., and Cleland, W.W. (2000) Biochemistry 39, 4821-4830] has indicated that Tyr229{\textquoteright} likely provides the other catalytic acid/base residue. Both of these residues are supplied by an adjacent subunit. Modeling Of L-Ru5P into the active site of the epimerase structure suggests that Tyr229{\textquoteright} is responsible for deprotonating L-Ru5P and Asp 120{\textquoteright} is responsible for deprotonating its epimer, D-Xu5P.},
	keywords = {CLASS-II, CLEAVAGE, ESCHERICHIA-COLI, MECHANISM, MUTAGENESIS, PHOSPHATE},
	isbn = {0006-2960},
	url = {<Go to ISI>://000172608100006},
	author = {Samuel, J. and Luo, Y. and Morgan, P. M. and Strynadka, N. C. J. and Tanner, M. E.}
}
@article {5075,
	title = {New mode of coordination for the dinitrogen ligand: Formation, bonding, and reactivity of a tantalum complex with a bridging N-2 unit that is both side-on and end-on},
	journal = {Journal of the American Chemical Society},
	volume = {123},
	number = {17},
	year = {2001},
	note = {ISI Document Delivery No.: 428CCTimes Cited: 84Cited Reference Count: 91},
	month = {May},
	pages = {3960-3973},
	type = {Article},
	abstract = {The reaction of a mixture of 1 equiv of PhPH2 and 2 equiv of PhNHSiMe2CH2Cl with 4 equiv of (BuLi)-Li-n followed by the addition of THF generates the lithiated ligand precursor [NPN]Li-2. (TKF)2(where [NPN] = PhP(CH2SiMe2NPh)(2)). The reaction of [NPN]Li-2. (THF)(2) with TaMe3Cl2 produces [NPN]TaMe3, which reacts under HZ to yield the diamagnetic dinuclear Ta(IV! tetrahydride ([NPN]Ta)(2)(mu -H)4 This hydride reacts with N-2 with the loss of H-2 to produce ([NPN]Ta(mu -H))(2)(mu-eta (1):eta (2)-N-2), which was characterized both in solution and in the solid state, and contains strongly activated Nz bound in the unprecedented side-on end-on dinuclear bonding mode. A density functional theory calculation on the model complex [(H3P)(H2N)(2)Ta(mu -H)](2)-mu-eta (1):eta (2)-N-2) provides insight into the molecular orbital interactions involved in the side-on end-on bonding mode of dinitrogen. The reaction of ([NPN]Ta(mu -H))(2)(mu-eta (1):eta (2)-N-2) with propene generates the end-on bound dinitrogen complex ([NPN]Ta(CH2CH2CH3))(2)(mu-eta (1):eta (1)-N-2), and the reaction of [NPN]Li-2. (THF)(2) with NbCl3-(DME) generates the end-on bound dinitrogen complex ([NPN]NbCl)(2)(mu-eta (1):eta (1)-N-2). These two end-on bound dinitrogen complexes provide evidence that the bridging hydride ligands are responsible for the unusual bonding mode of dinitrogen in ([NPN]Ta(mu -H))(2)(mu-eta (1):eta (2)-N-2). The dinitrogen moiety in the side-on end-on mode is amenable to functionalization; the reaction of ([NPN]Ta(mu -H))(2)(mu-eta (1):eta (2)-N-2) with PhCH2Br results in C-N bond formation to yield [NPN]Ta(mu-eta (1):eta (2)-N2CH2Ph)(mu -H)(2)TaBr[NPN]. Nitrogen-15 NMR spectral data an provided for all the tantalum-dinitrogen complexes and derivatives described.},
	keywords = {CHEMISTRY, CLEAVAGE, COMPOUND, CRYSTAL-STRUCTURE, MOLECULAR-STRUCTURES, NITROGEN-FIXATION, {ACTIVATION},
	isbn = {0002-7863},
	url = {<Go to ISI>://000168442700013},
	author = {Fryzuk,Michael D. and Johnson, S. A. and Patrick, B. O. and Albinati, A. and Mason, S. A. and Koetzle, T. F.}
}
@article {5138,
	title = {The structure of L-ribulose-5-phosphate 4-epimerase: An aldolase-like platform for epimerization},
	journal = {Biochemistry},
	volume = {40},
	number = {49},
	year = {2001},
	note = {ISI Document Delivery No.: 500CJTimes Cited: 18Cited Reference Count: 45},
	month = {Dec},
	pages = {14763-14771},
	type = {Article},
	abstract = {The structure of L-ribulose-5 -phosphate 4-epimerase from E. coli has been solved to 2.4 Angstrom resolution using X-ray diffraction data. The structure is homo-tetrameric and displays C-4 symmetry. Each subunit has a single domain comprised of a central beta -sheet flanked on either side by layers of alpha -helices. The active site is identified by the position of the catalytic zinc residue and is located at the interface between two adjacent subunits. A remarkable feature of the structure is that it shows a very close resemblance to that of L-fuculose-1-phosphate aldolase. This is consistent with the notion that both enzymes belong to a superfamily of epimerases/aldolases that catalyze carbon-carbon bond cleavage reactions via a metal-stabilized enolate intermediate. Detailed inspection of the epimerase structure, however, indicates that despite the close overall structural similarity to class II aldolases, the enzyme has evolved distinct active site features that promote its particular chemistry.},
	keywords = {CHEMISTRY, CLASS-II, CLEAVAGE, ENZYME, ESCHERICHIA-COLI, EVOLUTION, GALACTOSE, L-FUCULOSE-1-PHOSPHATE ALDOLASE, MECHANISM, SEQUENCE, SUPERFAMILIES},
	isbn = {0006-2960},
	url = {<Go to ISI>://000172608100005},
	author = {Luo, Y. and Samuel, J. and Mosimann, S. C. and Lee, J. E. and Tanner, M. E. and Strynadka, N. C. J.}
}
@article {4493,
	title = {A novel stepwise degradation of porphyrins. Synthesis and structural characterization of meso-tetraphenylchlorophinato nickel(II) and meso-tetraphenylsecochlorinato nickel(II)},
	journal = {Journal of the American Chemical Society},
	volume = {121},
	number = {11},
	year = {1999},
	note = {ISI Document Delivery No.: 180AUTimes Cited: 27Cited Reference Count: 33},
	month = {Mar},
	pages = {2609-2610},
	type = {Article},
	keywords = {CARBAPORPHYRINS, CLEAVAGE, DERIVATIVES, FLEXIBILITY, HYDROPORPHYRINS, macrocycle, SYSTEM},
	isbn = {0002-7863},
	url = {<Go to ISI>://000079363300039},
	author = {Bruckner, C. and Sternberg, E. D. and Macalpine, J. K. and Rettig, S. J. and Dolphin, D.}
}
@article {4470,
	title = {{Theoretical predictions and single-crystal neutron diffraction and inelastic neutron scattering studies on the reaction of dihydrogen with the dinuclear dinitrogen complex of zirconium [P2N2]Zr(mu-eta(2)-N-2)Zr[P2N2]},
	journal = {Journal of the American Chemical Society},
	volume = {121},
	number = {3},
	year = {1999},
	note = {ISI Document Delivery No.: 174NUTimes Cited: 67Cited Reference Count: 29},
	month = {Jan},
	pages = {523-528},
	type = {Article},
	abstract = {A single-crystal neutron diffraction analysis along with density functional calculations and incoherent inelastic neutron scattering studies has conclusively shown that the dihydrogen adduct of [P2N2]Zr(mu-eta(2)-N-2)Zr[P2N2] (1) (where P2N2 = PhP(CH2SiMe2NSiMe2CH2)(2)PPh) is [P2N2]Zr(mu-eta(2)-N2H)(mu-H)Zr[P2N2] (2), the complex with a bridging hydride and a N-N-H moiety, and not the dihydrogen complex [P2N2]Zr(mu-eta(2)-N-2)(mu-eta(2)-H-2)Zr[P2N2] (3), as was proposed on the basis of X-ray crystallographic data. In addition, DFT calculations show that the reaction of 1 with both H-2 and SiH4 is exothermic while an endothermic reaction is found for the reaction of 1 with CH4.},
	keywords = {CLEAVAGE, FIXATION, HYDROGEN},
	isbn = {0002-7863},
	url = {<Go to ISI>://000079041900006},
	author = {Basch, H. and Musaev, D. G. and Morokuma, K. and Fryzuk,Michael D. and Love, J. B. and Seidel, W. W. and Albinati, A. and Koetzle, T. F. and Klooster, W. T. and Mason, S. A. and Eckert, J.}
}
@article {4039,
	title = {Synthesis of novel diamagnetic chromium(II) alkyl complexes},
	journal = {Organometallics},
	volume = {16},
	number = {16},
	year = {1997},
	note = {ISI Document Delivery No.: XP426Times Cited: 7Cited Reference Count: 38},
	month = {Aug},
	pages = {3569-3571},
	type = {Article},
	abstract = {Reaction of Cr(NO)((NPr2)-Pr-i)(3) with PhCO2H leads to Cr(NO)((NPr2)-Pr-i)(O2CPh)(2) (1). The benzoate ligands of 1 may be replaced to form the diamagnetic, structurally-characterized organometallic complexes CpCr(NO)-((NPr2)-Pr-i)(OC(O)Ph) (2), CpCr(NO)((NPr2)-Pr-i)(CH2SiMe3) (3),and Cr(NO)((NPr2)-Pr-i)(CH2SiMe3)(2) (4).},
	keywords = {CLEAVAGE, LIGANDS, MOLYBDENUM, ORGANOMETALLIC CHEMISTRY, REACTIVITY, TUNGSTEN},
	isbn = {0276-7333},
	url = {<Go to ISI>://A1997XP42600001},
	author = {Kuzelka, J. and Legzdins,Peter and Rettig, S. J. and Smith, K. M.}
}
@article {3290,
	title = {THE REACTION OF PHSR(R=FC OR PH) WITH RU-3(CO)(12)},
	journal = {Polyhedron},
	volume = {14},
	number = {19},
	year = {1995},
	note = {ISI Document Delivery No.: RU147Times Cited: 6Cited Reference Count: 28},
	month = {Sep},
	pages = {2653-2661},
	type = {Article},
	abstract = {{The reaction of SPh(2) with Ru-3(CO)(12) affords (mu-SR)(mu-eta(1); eta(6)-C6H5)Ru-3(CO)(8) (Ru-Ru)},
	keywords = {BONDS, CLEAVAGE, CLUSTERS, COMPLEXES, NUCLEARITY, PHENYL, SULFIDES, TRICARBONYL},
	isbn = {0277-5387},
	url = {<Go to ISI>://A1995RU14700008},
	author = {Cullen, W. R. and Rettig, S. J. and Zheng, T. C.}
}
@article {2772,
	title = {CRYSTAL AND MOLECULAR-STRUCTURES OF OS3(CO)9[MU(3)-(C5H4PR)FE(C5H4)] (R = FC OR PH), 2 MOLECULES WITH FE -] OS BONDS},
	journal = {Journal of Organometallic Chemistry},
	volume = {452},
	number = {1-2},
	year = {1993},
	note = {ISI Document Delivery No.: LM427Times Cited: 12Cited Reference Count: 16},
	month = {Jun},
	pages = {97-103},
	type = {Article},
	abstract = {{The thermal reaction between Os3(CO)12 and Fe(C5H4)2PPh affords Os3(CO)9[mu3-(C5H4PPh)Fe(C5H4)](5b) (70\%) as the only major product. Heating a solution of Os3(CO)11(PFc2Ph) (FcH = (eta-C5H5)2Fe) in octane for 3 h gives the related molecule Os3(CO)9[mu3-(C5H4PFc)Fe(C5H4)] (5a) in low yield (5\%). The structures of 5a and 5b have been established by X-ray crystallography, revealing in each case that a closed Os3-triangle is capped on one face by the ferrocenyl phosphido moiety acting as an overall six-electron donor. It is bonded to the cluster via one phosphorus atom, one carbon atom from the C5H4 ring, and the iron atom. Two semibridging carbonyls are also present in each structure. Crystals of {mu3-[eta5-C5H4)2Fe]P[(eta3-C5H4)Fe(eta5-C5H5)]-Fe,P,P,C}Os3(CO)9 (5a) are triclinic, a 12.304(1), b 12.336(2), c 10.886(2) angstrom, alpha 115.38(2), beta 92.34(1), gamma 91.76(1)-degrees},
	keywords = {CLEAVAGE, CLUSTERS, CONVERSION},
	isbn = {0022-328X},
	url = {<Go to ISI>://A1993LM42700016},
	author = {Cullen, W. R. and Rettig, S. J. and Zheng, T. C.}
}
@article {7203,
	title = {IRON PORPHYRIN CATALYZED OXIDATION OF LIGNIN MODEL COMPOUNDS - THE OXIDATION OF VERATRYL ALCOHOL AND VERATRYL ACETATE},
	journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie},
	volume = {70},
	number = {8},
	year = {1992},
	note = {ISI Document Delivery No.: JW564Times Cited: 13Cited Reference Count: 43},
	month = {Aug},
	pages = {2314-2318},
	type = {Article},
	abstract = {meso-Tetra(2,6-dichloro-3-sulfonatophenyl)porphyrin iron chloride catalyzes the oxidation of 3,4-dimethoxybenzyl alcohol (veratryl alcohol) in aqueous solution to give veratraldehyde along with demethoxylation and ring-cleavage products. The isolation of a direct ring-cleavage product from the oxidation of veratryl acetate in aqueous solution supports the previously proposed ring-cleavage mechanisms. The oxidation in methanol, however, does not lead to ring-cleavage products. When veratryl alcohol was oxidized in methanol, solvent was found to be incorporated into the 3-position of veratryl alcohol, giving new insight into the mechanism of oxidation.},
	keywords = {3, 4-DIMETHOXYBENZYL ALCOHOL, BASIDIOMYCETE PHANEROCHAETE-CHRYSOSPORIUM, BOND-CLEAVAGE, C, CLEAVAGE, DEGRADING ENZYME, DIARYLPROPANE OXYGENASE, EXTRACELLULAR, HEME-ENZYME, LIGNINASES, RING, SPECTRAL CHARACTERIZATION, WHITE ROT BASIDIOMYCETE},
	isbn = {0008-4042},
	url = {<Go to ISI>://A1992JW56400025},
	author = {Cui, F. T. and Dolphin, D.}
}
