Synthesis of tetrakis(alkylisocyanide) bis(triphenylstibine)cobalt(II) and tetrakis(alkylisocyanide) bis(triphenylstibine oxide)cobalt(III) complexes: ligand substitution and oxidation in pentakis(alkylisocyanide)cobalt(II)

• Published in: Inorganica Chimica Acta Vol. 334; pp. 327 - 333
• Main Authors: Becker, Clifford A.L., Sebobi, Galaletsang S., Simane, Ntshekelang Tostic
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 30.05.2002
• Subjects: Alkylisocyanide; Cobalt(II) complexes; Cobalt(III) complexes; Ligand-substitution reactions; Triphenylstibine; Triphenylstibine oxide; Cobalt(II) complexes; Cobalt(III) complexes; Ligand-substitution reactions; Triphenylstibine; Triphenylstibine oxide; Alkylisocyanide
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/S0020-1693(02)00858-7

The complexes, [Co(CNC 4H 9- n) 4(SbPh 3) 2](ClO 4) 2, [Co(CNC 6H 11) 4(SbPh 3) 2](ClO 4) 2, [Co(CNC 6H 11) 4(OSbPh 3) 2](ClO 4) 3, and [Co(CNCH 2Ph) 4(OSbPh 3) 2](BF 4) 3, have been synthesized by reaction of excess SbPh 3 with the Co(II)–alkylisocyanide salts. With CNC 6H 11, the Co(II) complex can be isolated, continued reaction in solution producing the Co(IIl) complex. With CNCH 2Ph, reaction proceeds more rapidly through a Co(II) complex directly to the Co(III) complex isolated. With CNC 4H 9- n, only the Co(II) complex is observed; attempted further reaction causes decomposition to OSbPh 3. Characterization of the complexes is primarily in the solid state due to limited stability in solution. Coordination stereochemistries for both Co(II) and Co(III) complexes appear to be trans-substituted octahedral. Magnetic moments for [Co(CNC 4H 9- n) 4(SbPh 3) 2](ClO 4) 2 and [Co(CNC 6H 11) 4(SbPh 3) 2](ClO 4) 2 are low-spin ( μ eff=1.94 BM, 2.27 BM, respectively), as expected, while [Co(CNCH 2Ph) 4(OSbPh 3) 2](BF 4) 3 and [Co(CNC 6H 11) 4(OSbPh 3) 2](C1O 4) 3 are intermediate-spin ( μ eff=3.30, 3.70 BM, respectively), as expected. Six-coordinate Co(III) complexes, in which both Co(II) and SbPh 3 have been oxidized in the reaction, appear to be favored over the six-coordinate Co(II) complexes. Reactions of SbPh 3 with pentakis(alkylisocyanide)cobalt(II) complexes are thus drastically different from reactions with PPh 3 and even AsPh 3. Two low-spin Co(II) complexes, trans-[Co(CNC 6H 11) 4(SbPh 3) 2](ClO 4) 2 and trans-[Co(CNC 4H 9- n) 4(SbPh 3) 2](ClO 4) 2 ( μ eff=2.27, 1.94 BM), and two intermediate-spin Co(III) complexes, trans-[Co(CNC 6H 11) 4(OSbPh 3) 2](ClO 4) 3 and trans-[Co(CNCH 2Ph) 4-(OSbPh 3) 2](BF 4) 3 ( μ eff=3.70, 3.30 BM), have been synthesized by reaction of SbPh 3 with alkylisocyanide–Co(II) complexes and characterized.