Cobalt(II,III) and copper(II) complexes of 3-(2-furylidene) hydrazino-5,6-diphenyl-1,2,4-triazine

A new series of cobalt(II, III) and copper(II) complexes of 3-(2-furylidene) hydrazino-5,6-diphenyl-1,2,4-triazine (L) having formulae LM^IIX₂, L₂M^IIX₂ and LCo^IIIX₃, (X = Cl, OAc or ClO₄; M^II = Co^II or Cu^II) were isolated and characterized by elemental analyses, molar conductances, magnetic moments and i.r., electronic and e.s.r. spectral measurements. The i.r. spectra indicated that the ligand, L, behaves as a neutral bidentate towards divalent metal ions via a triazine-N, and azomethine-N, and acts as a tridentate towards cobalt(III) via the same two nitrogen atoms and the furan-O. The magnetic moments and electronic spectral data suggest a pseudo-tetrahedral geometry for L₂Co]Cl₂, a diamagnetic tetragonally distorted octahedral geometry for LCoCl₃], LCo(OAc)₃] · 4H₂O and LCo(H₂O)₃](ClO₄)₃ and a dimeric square pyramidal geometry for both LCuCl₂] and LCu(OAc)₂] · 2H₂O through bridged chloro and acetato ligands, respectively. The ligand field parameters (B, 10Dq and ) were evaluated from the electronic spectral data and magnetic moments and related to the bonding of the complexes. The X-band e.s.r. spectra showed three g values with large magnetic anisotropy for L₂Co]Cl₂ in accordance with pseudo-tetrahedral Co^II complexes; axial pattern for LCuCl₂], LCu(OAc)₂] · 2H₂O and L₂Cu(H₂O)₂](ClO₄)₂ with two g values and a signal due to M _s = ±2 transition for both chloro and acetato copper(II) complexes.