Amides as ligands—VIII: Inorganic complexes of γ-butyrolactam and N-methyl-γ-butyrolactam

Abstract

A series of metal complexes of γ-butyrolactam (BuL) and N-methyl-γ-butyrolactam (NMBuL) have been synthesized, showing co-ordination through the oxygen atom. The perchlorate salts of these complexes have a composition of the general formulas [M(BuL) 6] n+ (ClO 4) n , and [M(NMBuL) 4 or 6] n+ (ClO 4) n (M = Cr 3+, Al 3+, Fe 2+, Mn 2+, Co 2+, Ni 2+, Cu 2+, Cd 2+, Zn 2+, Ca 2+, Mg 2+). The halide complexes of the Co 2+, Cu 2+, Mn 2+ and Fe 3+ show, however, a marked structural difference from the perchlorate complexes. The Co(II) halides exhibit the general formula [Co(BuL) 6][CoX 4] (X = Cl, Br, I and SCN), indicating octahedral cationic and tetrahedral anionic species. The Cu(II) and Mn(II) chlorides have structures of the general formula [M(BuL) 2Cl 2] and [M(BuL)Cl 2]. A complex having the formula [Mn(NMBuL)Cl 2] has also been isolated. The Fe(III) chloride complex exhibits the structure of the type [FeL 4Cl 2][FeCl 4]. These complexes have been characterized by their i.r. spectra, electrical conductivity measurements, magnetic moments, X-ray diffraction patterns and electronic absorption spectra. The ligand field parameters Dq, B′ and β have been calculated for the octahedral cobalt(II) perchlorate complexes, and the tetrahedral [CoX 4] 2− species, verifying the proposed geometries and confirming the previously suggested donor order of BuL > NMBuL in the spectrochemical series.