Probe for the electronics of base-stabilized group 11 metal cations

A number of trimetalloborides have been synthesized through the reactions of base-stabilized coinage metal chlorides with a dimanganaborylene anion in hopes of using this inorganic platform to compare and evaluate the electronics of these popular coinage metal fragments. The adducts of Cu(I), Ag(I) and Au(I) stabilized by triphenylphosphine (PCy3), N-1,3-bis(4-methylphenyl)imidazol-2-ylidene) (ITol) and 1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene) (CAAC) with [(Cp(CO)2Mn)2B]– were studied spectroscopically, structurally and computationally. The geometries of the adducts fell into two classes, on symmetric and one asymmetric, each relying on the combined characteristics of both metal and ligand. The energetic factors proposed as the cause of the structural differences were investigated by ETS-NOCV analysis, which showed the final geometry to be controlled by competition between the tendency of the metal for higher or lower coordination number and the willingness of the cationic fragment to participate in backbonding interactions