Synthesis and reactions of alkyne complexes [MoCl(GeCl3)-(CO)(NCMe)(PPh3)(η2-RC2R)](R = Me or Ph) containing six different monodentate ligands
Abstract
The complex [MoCl(GeCl3)(CO)2(NCMe)2(PPh3)] reacts with RC2R (R = Me or Ph) in CH2Cl2 to give alkyne complexes [MoCl(GeCl3)(CO)(NCMe)(PPh3)(η2-RC2R)](R = Me 1 or Ph 2) containing six different monodentate ligands. Reaction of 1 with an equimolar quantity of L [L = PPh3, PPh2(C6H11), PMe2Ph, imidazole or 2-methylimidazole] afforded complexes [MoCl(GeCl3)(CO)L(PPh3)(η2-MeC2Me)] in high yield. Equimolar quantities of 1 and L–L {L–L = Ph2P(CH2)nPPh2(n= 1–6), [Fe(η5-C5H4PPh2)2], (C6H11)NCHCH
N(C6H11), 2,2′-bipyridine, 1,10-phenanthroline, 4,7-dimethyl-1,10-phenanthroline, 5,6-dimethyl-1,10-phenanthroline, S2CP(C6H11)3 or Ph2P(CH2)2PPh(CH2)2PPh2} gave [MoCl(GeCl3)(CO)(PPh3){σ-Ph2P(CH2)PPh2}(η2-MeC2Me)] and the cationic complexes [Mo(GeCl3)(CO)(PPh3)(L–L)(η2-MeC2Me)]Cl in good yield. The cationic nature of several of these complexes was confirmed by exchange with Na[BPh4] to afford complexes with tetraphenylborate as the counter anion. The fluxionality of some of the complexes was detertmined by variable-temperature 1H NMR spectroscopy. Solution and solid-state 13C NMR spectroscopy was used to confirm that the alkyne ligand in several of these complexes is donating four electrons to the molybdenum.