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

The new compounds [K(18-crown-6)][SCNB(C6F5)3](1), [K(18-crown-6)][(C6F5)3B((mu)-NC)B(C6F5)3](2), [K(18-crown-6)][NCB(C6F5)3] (3), [Me3Si((mu)-NC)B(C6F5)3](4) and [Hg{((mu)-CN)B(C6F5)3}2](5) have been synthesised. Reaction between [IrCl(PPh3)2(CO)] and one equivalent of 4 gives [Ir{((mu)-NC)B(C6F5)3}(PPh3)2CO](6). Similarly, the reaction between [Fe((eta)-C5H5)(CO)2Cl] and 4 gives [Fe{((mu)-NC)B(C6F5)3}((eta)-C5H5)(CO)2](7a). The NMR-scale reaction between [Fe((eta)-C5H5)(CO)2CN] and B(C6F5)3 gives the isomer [Fe{((mu)-CN)B(C6F5)3}((eta)-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 ((mu)-CN)B unit. The compounds containing the isomeric bridging ((mu)-CN)B or ((mu)-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.