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

The new compounds [K(18-crown-6)][SCNB(C6F5)(3)] (1), [K(18-crown-6)][(C6F5)(3)B(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)(2)CO] (6). Similarly, the reaction between [Fe(eta-C5H5)(CO)(2)Cl] and 4 gives [Fe{(mu-NC)B(C6F5)(3)}(eta-C5H5)(CO)(2)] (7a). The NMR-scale reaction between [Fe(eta-C5H5)(CO)(2)CN] 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 B-11{H-1} NMR spectroscopy and by DFT calculations. The B-11{H-1} NMR spectra enable distinction between the isomers. The single-crystal X-ray structures of 1, 3 and 7a have been determined.