Triphenylboron adducts of redox-active cyanomanganese ligands

The reaction of [Mn(CN)(PR3)(NO)(eta-C5H4Me)] (R = Ph or OPh) with [AuCl(th t)] (tht = tetrahydrothiophene) in the presence of Na[BPh4] gave [Mn(CNBPh3 )(PR3)(NO)(eta-C5H4Me)], X-ray studies on which (R = OPh) confirm addition of triphenylboron to the nitrogen atom of the cyanomanganese centre. Compar ison of the geometry of the Ph3B-NC interaction, as measured by the mean C- B-C angle and mean B-C length, with those of L . BPh3 species in the Cambri dge Structural Database showed the manganese ligand to be a relatively weak donor comparable with a range of other N and O ligands. The complexes [Mn( CNBPh3)(PR3)(NO)(eta-C5H4Me)], as well as cis-[Mn(CNBPh3)(CO)(2){P(OEt)(3)} (dppm)] and trans-[Mn(CNBPh3)(CO)(dppm)(2)], can be prepared directly from BPh3 and the appropriate cyanomanganese ligand. Each of the complexes under goes one-electron oxidation at a platinum disc electrode in CH2Cl2 and the reaction of trans-[Mn(CNBPh3)(CO)(dppm)(2)] with [Fe(eta-C5H5)(2)][PF6] giv es trans-[Mn(CNBPh3)(CO)(dppm)(2)][PF6].