Synthesis of a Tri(gold)boride Complex (Cy_3P)B[AuP(o-Tol)_3]_3

摘要

A tri(gold)boride of the formula B[AuP(o-Tol)_3]_3 (2) is generated in the reaction of the silylated phosphine borane Cy_3PBH_2SiMe_3 with the tri(gold)oxonium tetrafluoroborate [(o-Tol)_3PAu]_3O~+ BF_4~- and isolated as its stable 1: 1 complex with tricyclohexylphosphine: Cy_3PB[AuP(o-Tol)_3]_3. The composition of the product has been confirmed by elemental analyses and mass spectrometry. Solution NMR data of 2 indicate a molecular structure with C_(3v) symmetry which has been confirmed by MP2 calculations for the model system H_3PB(AuPH_3)_3. The compound is a rare case of a trimetallated boride which is isolobal with the simple phosphineborane Cy_3PBH_3. With reagents bearing less bulky substituents (R_3 = ~iPr_3, MePh_2, Ph_3), the reactions proceed to salts with the tetra-aurated cations [Cy_3PB(AuPR_3)_4]~+.