Synthesis and study of new binuclear compounds containing bridging (μ-CN)B(C 6 F 5 ) 3 and (μ-NC)B(C 6 F 5 ) 3 systems

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.