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Abstract
A series of complexes having the general formula, [Co(CNR)3(PR3)2]X2, X = ClO4, BF4 with CNR = CNCMe3, CNCHMe2, CNC6H11. CNCH2Ph and PR3 = PPh3, P(C6H4Me-p)3, P(C6H4OMe-p)3 has been synthesized and characterized. Synthesis can be achieved by reaction of [Co(CNR)4(AsPh3)2]X2 complexes with controlled excess of PR3 ligands, and by AgClO4/AgBF4 oxidation of the [Co(CNR)3(PR3)2]X complexes. The latter procedure is preferable. Alternate syntheses of the [Co(CNR)3(PR3)2]X complexes have also been employed. Five-coordinate Co(II) complexes have not been obtained using CNCMe3 with P(C6H4Me-p)3 ligands, CNCH2Ph with P(C6H4OMe-p)3 ligands, or CNC4H9-n with PPh3 ligands. [Co(CNC-Me3)3{P(C6H4Cl-p)3}2]ClO4 produced only [Co{CNCMe3)4H2O](ClO4)2 upon forced oxidation with excess AgClO4. [Co(CNR)3(PR3)2]X2 complexes appear to undergo varying degrees of distortion from regular (i.e., D 3h symmetry) axially-disubstituted trigonal bipyramidal coordination in the solid state, as evidenced by v(-N°C) IR patterns, but to assume regular trigonal bipyramidal coordination in solution. Effective magnetic moments indicate one-electron paramagnetism, and solution electronic spectra are compatible with trigonal bipyramidal coordination.
