Synthesis and selected reactions of pentakis ( t -octylisocyanide)cobalt(II) complexes

Abstract

The ligand 1,1,3,3-tetramethylbutylisocyanide, CNCMe2CH2CMe3, i.e. t-octylisocyanide, with Co(ClO4)2 · 6H2O or Co(BF4)2 · 6H2O in ethanol, produces pentakis(alkylisocyanide)cobalt(II) complexes, [Co(CNC8H17-t)5](ClO4)2 (1) and [Co(CNC8H17-t)5](BF4)2 · 2.0H2O (2). These Co(II) complexes undergo reduction/substitution upon reaction with trialkylphosphine ligands to produce [Co(CNC8H17-t)3{P(C4H9-n)3}2]ClO4 (3), [Co(CNC8H17-t)3{P(C4H9-n)3}2]BF4 (4), and [Co(CNC8H17-t)3{P(C3H7-n)3}2]ClO4 (5). Complex 3 is oxidized with AgClO4 to produce [Co(CNC8H17-t)3{P(C4H9-n)3}2](ClO4)2 (6). Complex 1 yields [Co(CNC8H17-t)4py2](ClO4)2 (7) upon dissolving in pyridine. Reactions with triarylphosphine and triphenylarsine ligands were unsatisfactory. The chemistry of 1 and 2 is therefore more similar to that of Co(II) complexes with CNCMe3 than with CNCHMe2, other alkylisocyanides, or arylisocyanides, but shows some behavior dissimilar to any known Co(II) complexes of alkylisocyanides or arylisocyanides. Infrared and electronic spectra, magnetic susceptibility, molar conductivities, and cyclic voltammetry are reported and compared with known complexes. 1H, 13C, and 31P NMR data were also measured for the diamagnetic complexes 3, 4, and 5.