Benzoylhydrazine and isonitrosoacetone react in ethanol with cobalt, nickel, and copper halides and acetates to give the coordination compounds MX2(HL) . nH(2)O, MX2(HL)(2) . nH(2)O, and ML2 . nH(2)O [M = Col Ni, Cu; X = Cl, Br; HL = C6H5C(O)NHNC(CH3)CHNOH; n = 1-4]. The same reactions pet-formed in the presence of sodium acetate and pyridine (pH 7-8) yield the complexes MLCl . nH(2)O and MPy2LCl . nH(2)O (n = 1-4). All the complexes have a pseudooctahedral coordination geometry. The hydrazone HL behaves as a tridentate O,N,N-donor ligand. Thermolysis of the substances involves dehydration (70-90degreesC), deaquation (155-170degreesC) or deamination (175-195degreesC), and complete thermal decomposition (285-360degreesC).