SYNTHESIS AND REACTIONS OF ALKYNE COMPLEXES [MOCL(GECL3)-(CO)(NCME)(PPH3)(ETA-2-RC2R)] (R = ME OR PH) CONTAINING 6 DIFFERENT MONODENTATE LIGANDS

The complex [MoCl(GeCl3)(CO)2(NCMe)2(PPh3)] reacts with RC2R (R = Me o r Ph) in CH2Cl2 to give alkyne complexes [MoCl(GeCl3)(CO)(NCMe)(PPh3)( eta2-RC2R)] (R = Me 1 or Ph 2) containing six different monodentate li gands. Reaction of 1 with an equimolar quantity of L [L = PPh3, PPh2(C 6H11), PMe2Ph, imidazole or 2-methylimidazole] afforded complexes [MoC l(GeCl3)(CO)L(PPh3)(eta2-MeC2Me)] in high yield. Equimolar quantities of 1 and L-L {L-L = Ph2P(CH2)nPPh2 (n = 1-6), [Fe(eta5-C5H4PPh2)2], (C 6H11)N=CHCH=N(C6H11), 2,2'-bipyridine, 1,10-phenanthroline, 4,7-dimeth yl-1,10-phenanthroline, 5,6-dimethyl-1,10-phenanthroline, S2CP(C6H11)3 or Ph2P(CH2)2PPh(CH2)2PPh2} gave eCl3)(CO)(PPh3){sigma-Ph2P(CH2)PPh2} (eta2-MeC2Me)] and the cationic complexes [Mo(GeCl3)(CO)(PPh3)(L-L)(et a2-MeC2Me)]Cl in good yield. The cationic nature of several of these c omplexes was confirmed by exchange with Na[BPh4] to afford complexes w ith tetraphenylborate as the counter anion. The fluxionality of some o f the complexes was determined by variable-temperature H-1 NMR spectro scopy. Solution and solid-state C-13 NMR spectroscopy was used to conf irm that the alkyne ligand in several bf these complexes is donating f our electrons to the molybdenum.