Quinoxaline 1-oxide complexes with transition metal chlorides[1

Abstract

3 d metal chloride complexes with quinoxaline 1-oxide (NQxO) were prepared by allowing ligand and salt solutions, pretreated with molecular sieve 4A, to interact. Complexes of the following stoicheiometries were obtained: (CrCl 3)(NQxO) 3·12H 2O, MNCl 2(NQxO) 2, (FeCl 3)(NQxO) 3·2H 2O, CoCl 2(NQxO) 3·5H 2O, NiCl 2(NQxO) 2, CuCl 2(NQxO) 2·3H 2O and ZnCl 2(NQxO). Characterization of the new metal complexes was based on spectral and magnetic studies. The overall evidence suggests that these compounds are bi- or poly-nuclear. Likely structures involve: Both terminal and bridging unidentate O-bonded NQxO and chloro ligands for the Cr(III) and Fe(III) complexes; chloride bridging and exclusively therminal NQxO for the Mn(II), Ni(II), and Cu(II) compounds; NQXO appears to be O-bonded in the Mn(II) and N-bonded in the Ni(II) and Cu(II) complexes; the Zn(II) complex contains terminal chloro and bridging dibentate, O, N-bonded NQxO; and the Co(II) compound appears to involve both terminal, N-bonded, and bridging bidentate, O, N-bonded NQxO. The Zn(II) complex is probably tetrahedral, the Mn(II) compound pentacoordinated, and the rest of the new complexes hexacoordinated. With the exception of the Fe(III) complex, which probably involves spin-free-spin-paired equilibria ( μ eff = 3.71 BM), the new metal complexes are magnetically normal high-spin compounds.