Metalloboranes. I. Metal complexes of B3, B9, B9S, B10, and B11 borane anions

Article abstract of DOI:10.1021/ic50069a020

Triborohydride ion (B₃H₈^-) reacts with metal hexacarbonyls to give M(CO)₄B₃H₈^- with M = Cr, Mo, W. Isolated as crystalline salts, these anions are yellow and air stable. The triborohydride moiety is attached to the metal atom in these complexes by means of two adjacent M-H-B three-center bonds as shown by the crystal structure analysis of a Cr(CO)₄-B₃H₈^- salt. An identical mode of structural attachment is proposed for the complexes of [(C₈H₅)₃P]₂M′B ₃H₈ (M′ = Cu, Ag) and (C₅H₅)₂TiB₃H₈. The fragment anions B₉H₁₄^- and B₉H₁₂S^- form a series of colorless tristriphenylphosphine complexes of copper, silver, and gold which appear to be simple salts in the solid state and in highly polar media. X-Ray studies of the gold derivative show a trigonal P₃Au⁺ cation and a B₉H₁₂S^- anion with the predicted B₉S skeleton (B₁₀H₁₄^2- analog). In solution, particularly nonpolar media, there appears to be a significant interaction between the cation and the anion as evidenced by the perturbation of the characteristic B₉H^14- and B₉H₁₂S^- B¹¹ nmr spectra. Analogous metal complexes derived from B₁₀H₁₃^- show varied behavior and in some of these, particularly the copper derivative, there may be metalborane interactions. The properties of copper and gold phosphine derivatives of B₁₁H₁₄^- are consonant with simple salts of B₁₁H₁₄^-.