Chemical and Electrochemical Oxidation of Diphenylphosphide-Bridged Hydrides [M2(η5-C5H5)2(μ-H)(μ-PPh2)(CO)4] and Anions [M2(η5-C5H5)2(μ-PPh2)(CO)4]- (M = Mo, W)

Reaction of the hydride complexes [M 2 Cp 2 (μ-H)(μ-PPh 2 )(CO) 4 ] (M = Mo, W; Cp = η 5 -C 5 H 5 ) with [FeCp 2 ]BF 4 proceeds in a 1:2 ratio to give the unsaturated tetracarbonyl salts [M 2 Cp 2 -(μ-PPh 2 )(CO) 4 ]BF 4 , which spontaneously (M = Mo) or in the presence of CO (M = W) transform into the corresponding electron-precise pentacarbonyls [M 2 Cp 2 (μ-PPh 2 )(μ-CO)-(CO) 4 ]BF 4 . In contrast, reaction of the above hydride complexes with [FeCp 2 ](BAr' 4 ) (Ar' = 3,5-C 6 H 3 (CF 3 ) 2 ) proceeds in a 1:1 ratio to give the paramagnetic salts [M 2 Cp 2 (μ-H)(μ-PPh 2 )-(CO) 4 ](BAr' 4 ). No further reaction takes place with [FeCp 2 ](BAr' 4 ) unless a proton acceptor such as water or tetrahydrofuran is present, in which case the corresponding salts [M 2 Cp 2 -(μ-PPh 2 )(CO) 4 ](BAr' 4 ) or [M 2 Cp 2 (μ-PPh 2 )(μ-CO)(CO) 4 ](BAr' 4 ) are rapidly formed. Reactions of the anions [M 2 Cp 2 (μ-PPh 2 )(CO) 4 ] - (as (H-DBU) + salts, DBU = 1,8-diazabicyclo[5.4.0]undec-7-ene) with [FeCp 2 ]BF 4 proceed stepwise to give first the 33-electron radicals [M 2 Cp 2 (μ-PPh 2 )(CO) 4 ], which can be isolated as very air-sensitive green solids, and then the unsaturated salts [M 2 Cp 2 (μ-PPh 2 )(CO) 4 ]BF 4 , which are identical to those formed from the neutral hydrides. The structure and dynamic behavior of the new compounds are analyzed on the basis of solution IR, 1 H, 3 1 P, and 1 3 C NMR or ESR spectroscopic data. In addition, the redox and other chemical transformations connecting all the new compounds are??