Synthesis and Structural Investigation of Novel Mixed-Ligand Cyanonitrosyl {CrNO}⁵ Chelates of Monovalent Chromium with Some Bidentate 4-Acyl-2-pyrazoline-5-ones

Abstract

Novel mixed-ligand cyanonitrosyl chelates of chromium(I), formed by the interaction of potassium pentacyanonitrosylchromate(I) monohydrate, K₃-[Cr(NO)(CN)].H₂-O, with some bidentate 4-acyl-2-pyrazoline-5-ones (derived from 3-methyl-l-phenyl/(3′-chlorophenyl)-2-pyrazoline-5-one and different acylchlorides), viz, 4-butyryl-3-raethyl-l-phenyl-2-pyrazoline-5-one (I), 4-chloroacetyl-3-methyl-l-phenyl-2-pyrazoline-5-one (II), 4-p-chlorobenzoyl-3-methyl-l-phenyl-2-pyrazoline-5-one (III) and 4-acetyl-l-(3′-chlorophenyl) -3-methyl-2-pyrazoline-5-one (IV) have been isolated in the solid state. The compounds, which have been characterized by elemental analyses, molar conductances, molecular weight determinations, magnetic measurements, thermogravimetric analyses, electron spin resonance, uv-vis. and infrared spectral studies, have the general formula, [cr(NO) (CN) ₂(L-L) (H₂0)] (where L-L = 4-acyl-2-pyrazoline-5-ones mentioned above), for which an octahedral structure has been proposed. Chromium(I) has a low-spin [CrNO}⁵ electron configuration¹ in all the complexes.