DEPROTONATION OF RHENIUM TERMINAL ACETYLIDE COMPLEXES OF THE FORMULA (ETA-5-C5R5)RE(NO)(PPH3)(CCH) - GENERATION AND REACTIVITY OF RHENIUM LITHIUM C2 COMPLEXES

Reactions of methyl complexes (eta5-C5R4R')Re(NO)(PPh3)(CH3) (R/R' = H/H, H/CH3, CH3/CH3) with HBF4.0Et2, chlorobenzene, and R"C=CH (R" = H, CH3) give terminal alkyne complexes [eta5-C5R4R')-Re(NO)(PPh3(R"C=CH)]+BF4- (72-87%). When R" = CH3, equilibria with methylvinylidene complexes [(eta5-Cr5R4R')Re(NO)(PPh3)(=C=CHCH3)]+BF4- can be effected at 90-65-degrees-C (75-99% conversion). Treatment of the alkyne or vinylidene complexes with t-BuO-K+ gives acetylide complexes (eta5-C5R4R')-Re(NO)(PPh3)(C=CR") (R/R/R": 1, H/H/H; 3, H/H/CH3; 11, H/CH3/H; 12, H/CH3/CH3; 2, CH3/CH3/H; 17, CH3/CH3/CH3; 81-94%). Reactions of 1 with 1.0 and 2.0 equiv of n-BuLi give the lithiated complexes (eta5-C5H5)Re(NO)(PPh3)(C=CLi) and (eta5-C5H4Li)Re(NO)(PPh3)(C=CLi), respectively, as assayed by P-31 NMR and subsequent conversion with CH3I to 3 and 12. Reaction of 1 with 2.0 equiv of n-BuLi and Ph3SnCl gives the stannylated complex (eta5-C5H4SnPh3)Re(NO)(PPh3)(C=CSnPh3) (49%), which upon silica gel chromatography yields (eta5-C5H4SnPh3)Re(NO)(PPh3)(C=CH). Reaction of 2 with n-BuLi gives (eta-C5(CH3)5)Re(NO)(PPh3)(C=CLi), as assayed by subsequent reactions with CH3I, D20, Me3SiCl, and Ph3SnCl to give 17 (95%), 2-d1 (88%; 86-89% labeled), (eta5-C5(CH3)5)Re(NO)(PPh3)(C=CSi(CH3)3) (86%), and (eta5-C5(CH3)5)Re(NO)(PPh3)(C=CSnPh3) (45%).