Synthesis and study of new binuclear compounds containing bridging (μ-CN)B(C6F5)3 and (μ-NC)B(C6F5)3 systems

Abstract

The new compounds [K(18-crown-6)][SCNB(C₆F₅)₃] (1), [K(18-crown-6)][(C₆F₅)₃B(μ-NC)B(C₆F₅)₃] (2), [K(18-crown-6)][NCB(C₆F₅)₃] (3), [Me₃Si(μ-NC)B(C₆F₅)₃] (4) and [Hg{(μ-CN)B(C₆F₅)₃}₂] (5) have been synthesised. Reaction between [IrCl(PPh₃)₂(CO)] and one equivalent of 4 gives [Ir{(μ-NC)B(C₆F₅)₃}(PPh₃)₂CO] (6). Similarly, the reaction between [Fe(η-C₅H₅)(CO)₂Cl] and 4 gives [Fe{(μ-NC)B(C₆F₅)₃}(η-C₅H₅)(CO)₂] (7a). The NMR-scale reaction between [Fe(η-C₅H₅)(CO)₂CN] and B(C₆F₅)₃ gives the isomer [Fe{(μ-CN)B(C₆F₅)₃}(η-C₅H₅)(CO)₂] (7b). In the compounds 3, 4, 6 and 7a the anion [NCB(C₆F₅)₃]⁻ is coordinated to the metal through the nitrogen. Complexes 1, 2 and 7b incorporate a (μ-CN)B unit. The compounds containing the isomeric bridging (μ-CN)B or (μ-NC)B systems have been investigated by ¹¹B{¹H} NMR spectroscopy and by DFT calculations. The ¹¹B{¹H} NMR spectra enable distinction between the isomers. The single-crystal X-ray structures of 1, 3 and 7a have been determined.