Coordination compounds of tripodCo(II) and tripodCo(I) - Selective substitution and redox behaviour

The five-coordinate tripodCobalt(II) compound [tripodCo(II)Cl(2)] (2) [trip od = CH3C(CH2PPh2)(3)] undergoes selective substitution of its chlorine gro ups on activation with KPF6 in the first substitution step and by TlPF6 in the second. Compounds of the type [tripodCo(II)LL'](2+) with two nitrile (3 (2+)) or isonitrile (5(2+)) ligands are obtained by this route. Compounds [ tripodCo(II)L(2)] containing two equal ligands L are also accessible from C o-aq(II) as the starting material. The syntheses of [tripodCo(II)(CNR)(2)]( 2+) (5(2+)) and [tripodCo(II)X(2)] (X = CN, NCO, NCS) (6) are reported. Dif ferent routes to MpodCo(I) derivatives are described. Depending on the natu re of the co-ligands, four-coordinate - [tripodCo(I)NCO] (7) - or five-coor dinate - [tripodCo(I)(CNR)(2)](+) (5(+)) - compounds are obtained. Several high-yield syntheses of [tripodCo(I)-alkyne](+) (8(+)) compounds are report ed. The compounds are characterised by the usual analytical and spectroscop ic techniques including X-ray analysis of selected examples.