PPh,)(CO),Cp,]+['21 or 3.008(2) 8, in [Mo,(p-StBu),-Further evidence of the high electrophilicity of 2 is the unusual hydride abstraction forced upon BH3 . THE This occurs quickly in dichloromethane at -30 "C and gives the novel unsaturated hydrido complex 4-PF6 in very high yield (CO),Cp]Z + 1131).
[W,(p-H)(Co),(,~-dppm)Cp,I(PF,) (w= W 4-pF6 through spontaneous liberation of two CO ligands (Scheme 1). Compound 4-PF6 displays a resonance signal shifted to unusually low field for bridging hydrido ligands at 6 = -2.6,1141 which remains unchanged down to -90Β°C. This deshielding may be an effect of the metal-metal multiple bonding.[' As expected, this unsaturated hydrido complex reacts readily with CO to yield the saturated species 5 [W,(~-H)(CO),(,~-~PP~)CP,~(PF,) S-PF, (counterion PF, , two isomers),['61 similar to the dimolybdenum complex previously prepared by us,131 and its hydrido ligands show resonances in the usual region in the 'H NMR spectrum (6 = ca. -2O).["'
Other simple compounds interact with 2 at low temperatures. For example, 2 reacts instantaneously with MeOH at -30 "C to give the methoxy-bridged species 6,"" which is isostructural with compounds 3a and 3b. More complex reactions occur with compounds with P-H or C-H bonds, such as PPh,H, MeC(O)H, or HCrCPh, and these are currently under investigation.