ORGANOMETALLIC NITROSYL CHEMISTRY .48. REACTIVITIES OF REPRESENTATIVE CYCLOPENTADIENYL ETA-4-TRANS-DIENE NITROSYL COMPLEXES OF MOLYBDENUM TOWARD ACETONE

{When CpMo(NO)(eta-4-trans-butadiene) (Cp = eta-5-C5H5) is treated with acetone, a ligand-coupling reaction occurs to form two complexes having the composition CpMo(NO)(eta-4-CH2CHCHCH2CMe2O), one in which the allyl portion of the coupled ligand is endo (1A) and one in which the allyl is exo (1B) with respect to the Cp ligand. Complete structural assignment of 1A and 1B has been effected by using NMR spectroscopic methods. Similar treatment of Cp*Mo(NO)(eta-4-trans-butadiene) (Cp* = eta-5-C5Me5) affords a single organometallic product, 2, which is the Cp* analogue of 1A. The coupling reaction between CpMo(NO)(eta-4-trans-2,5-dimethyl-2,4-hexadiene) and acetone is fairly rapid, the initial products being the endo-allyl (3A) and exo-allyl (3B) complexes. The endo isomer, however, converts quickly and irreversibly to the exo-allyl isomer. If the latter reaction is left for 15 h at ambient conditions, then 3B and [CpMo(NO)]3(mu-2-eta-2-eta-1-O-CMe2)3, which is isolable as a THF solvate (4), are the only organometallic species present in the final reaction mixture. All new complexes isolated during this work have been fully characterized by conventional methods, and crystal structure analyses have been performed on 2, 3B, and 4. Crystals of Cp*Mo(NO)(eta-4-endo-CH2CHCHCH2CMe2O) (2) are orthorhombic, P2(1)2(1)2(1), with a = 9.2465 (15) angstrom