Preparation, Molecular Structure, and Solution Properties of 1-[1,1ʹ-Bis(Diphenylphosphino)ferrocene]palladatetraborane

1-[1,1ʹ-Bis(diphenylphosphino)ferrocene]palladatetraborane, 1-{(dppf)Pd}B₃H₇ (1), has been prepared by the reaction of (dppf)PdCl₂ with octahydrotriborate(1-). The molecular structure of 1 has been determined: triclinic, P1 (No. 2), a = 9.557 (1), b = 9.632 (1), c = 18.547 (2) Å, α = 75.39 (1), β = 80.72 (1), γ = 73.41 (1)°, Z = 2, V = 1575.9 (5) ų, R_F = 0.025. The triborane ligand is symmetrically disposed (within esd’s) with respect to the Pd atom; the central Pd–B distance is only slightly shorter (2.154 (3) Å) than the remaining two (2.190 (3) and 2.182 (3) Å). Borane hydrogen atoms have been located directly. Variable-temperature¹H NMR spectroscopic studies indicate that two fluxional processes involving the {(dppf)Pd} fragment are operational; at T ≥ 203 K, facile mutual twisting of the cyclopentadienyl rings occurs, while at T ≥ 293 K, inversion at each phosphorus atom is accessed. The borane ligand itself appears to be static on the 400-MHz time scale, although inversion at the phosphorus atoms effectively renders equivalent the two distinct terminal hydrogen atoms on each terminal boron atom. Complex 1 shows an irreversible redox process, contrasting with reversible processes observed for dppf and (dppf)PdCl₂.