Structural and computational studies of Cp(CO)2(PCy3)MoFBF3, a complex with a bound BF4- ligand

Hydride transfer from Cp(CO) 2 (PCy 3 )MoH to Ph 3 C + BF 4 - gives Cp(CO) 2 (PCy 3 )MoFBF 3 , and the crystal structure of this complex was determined. In the weakly bound FBF 3 ligand, the B–F(bridging) bond length is 1.475(8) A, which is 0.15 A longer than the average length of the three B–F(terminal) bonds. The PCy 3 and FBF 3 ligands are cis to each other in the four-legged piano stool structure. Electronic structure (DFT) calculations predict the trans isomer of Cp(CO) 2 (PCy 3 )MoFBF 3 to be 9.5 kcal/mol (in Δ G g, 298 ∘ ) less stable than the cis isomer that was crystallographically characterized. Hydride transfer from Cp(CO) 2 (PCy 3 )MoH to Ph 3 C + BAr 4 ′ - [ Ar ′ = 3 , 5 - bis(trifluoromethyl)phenyl ] in CH 2 Cl 2 solvent produces [ Cp ( CO ) 2 ( PCy 3 ) Mo ( ClCH 2 Cl ) ] + [ BAr 4 ′ ] - , in which CH 2 Cl 2 is coordinated to the metal.