Cobalt(II) and zinc(II) complexes of 1,1,5,5,-tetramethylcarbohydrazide
1983; Elsevier BV; Volume: 70; Linguagem: Inglês
10.1016/s0020-1693(00)82778-4
ISSN1873-3255
AutoresL. K. Peterson, R. S. DHAMI, Kwat I. Thé,
Tópico(s)Inorganic and Organometallic Chemistry
ResumoAbstract 1,1,5,5,-Tetramethylcarbohydrazide (Me2NNH)2CO(tmc) was synthesized via the thermal decomposition of the carbamate Me2NNHC(O)OSiMe3. The complexes Co(tmc)Cl2(III), Co(tmc)2Cl2(IV), Zn(tmc)Cl2(V) and Zn(tmc)2Cl2(VI) were prepared. These compounds are non-electrolytes in solution in acetone and nitromethane. The complexes III and V have pseudo tetrahedral structures in the solid state and in solution in acetone, in which they are monomeric. The most likely solid state structure for the M(tmc)2Cl2 complexes IV and VI is octahedral. In solution, however, complexes IV and VI are extensively dissociated, via loss of one tmc ligand, giving equilibrium mixtures containing the four-coordinate complexes III and V, respectively. In all four complexes, the tmc ligand chelates to the metal centre via the carbonyl oxygen and one of the terminal dimethylamino groups. The ligand in Zn(tmc)Cl2 is non-fluxional. Exchange among tmc ligands in solutions of Zn(tmc)2Cl2(VI) is rapid on the nmr time scale at temperatures above O °C.
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