The preparation is described of the compounds ML, X, (L = 1.2-dimethylimidazole; M = Co, X = I or NO,; M =Ni,X=CI.Br,I,orNO,; M=Cu,X=BrorNO,).ML,X,(M=Co,Ni.orZn.X=CI,Br,I,orNO3; M = c u , X = CI or NO3), CuL,CI, and ZnL,(N03),,H,0.Vibrational, electronic, and e.s.r. spectra and magnetic measurements are reported for these and structural information is deduced. The halogeno-complexes M L, X, have pseudotetrahedral structures and CoL, X, and ZnL,( NO3),.H,O are ptobably tetrahedral. The compounds NiLJ, (X = CI, Br, or I) are square and CuL,X, is five-co-ordinate. 1 D. M. L. Goodgame, M. Goodgame, and G. W. Rayner Canham, Inorg. Chim. Ada, 1969, 5, 399.4 : 1 ratio of ligand-to-metal was more difficult to obtain than for other substituted imidazole ligands and very few six-co-ordinate compounds were isolated.The 4 : 1 cobalt complexes were closely similar in their electronic spectral and magnetic properties ( Table 1) and they appear to contain tetrahedral COL,,+ ions. The A value of 5200 cm-l is greater than that of benzimidazole in C~(benzimidazole),(ClO~)~ (5100 cm-l) but slightly less than that of 2-methylimidazole (5250 cm-1) in spite of a probably increased basicity (N-methylimidazole is more basic than imidazole). The compounds CoL,X2 (X = C1, Br, or I) have electronic spectra typical of pseudo-tetrahedral complexes, with the 2 F. Akhtar and A. C. Skapski, unpublished observat;nns, 3 F. Akhtar, F. Huq, and A. C. Skapski, to be published. 4 T. Sundaresan, M.Sc. Thesis, London University, 1969. quoted in ref. 1.