Metal Cyanonitrosyl Complexes: Synthesis and Characterization of Some Novel Mixed-Ligand Cyanonitrosyl {CoNO}8a Complexes of Co(I) with Some Biologically Active Heterocyclic Donors

Abstract

Novel hexa-coordinate mixed-ligand cyanonitrosyl complexes of cobalt(I) having the general formula K2[Co(NO) (CN)4 (L)], where L = 3-methyl-1-phenyl-2-pyrazoline-5-one, 2,3-dimethyl-1-phenyl-3-pyrazoline-5-one, 4-amino-2,3-dimethyl-1-phenyl-3-pyrazoline-5-one, 2,3-dimethyl-4-dimethylaminome thanesulphona te sodium monohydrate-1-phenyl-3-pyrazoline-5-one, benzothiazole or 2-methylbenzothiazole were prepared by the interaction of K2[Co(NO) (CN)4 (H2O)]. H2O with L in aqueous ethanol solution. The products are characterized by elemental analyses, molar conductances, magnetic measurements, EPR and IR spectral studies and thermogravimetric analysis. Tetragonally distorated octahedral structures are proposed. Infrared spectral studies suggest that all 5-pyrazolone and benzothiazole derivatives act as neutral monodentate ligands which coordinate through the cyclic oxygen and tertiary nitrogen, respectively. Cobalt(I) has a low-spin {CoNO}8 electron configuration in all the complexes. These complexes behave as 2:1 electrolytes, and are diamagnetic. Referee I: S. M. Sokol Referee II: B. J. MacCormick aEnemark and Feltham have proposed circumventing the problem of the nature of the nitrosyl ligand by considering metal nitrosyls as containing an {M(NO)x}n group, where n is the number of d-electrons of M, plus the number of electrons in the ξ*-orbital of NO (or more conveniently, n is the number of d-electrons if nitrosyl is regarded as being coordinated as NO+). J.H. Enemrak and R.D. Feltham, Coord. Chem. Rev., 13, 339 (1974).