Synthesis and Structures of Zinc(II) and Cadmium(II) Complexes with ( η 6 ‐Benzenecarboxylate) Chromium Tricarbonyl and Pyrazole Derivatives

Abstract. Reaction of zinc acetate with four different substituted pyrazoles (3,5‐dimethyl pyrazole (3,5‐Me 2 PzH), 3,5‐di‐ tert ‐butyl pyrazole (3,5‐ t Bu 2 PzH), 3,5‐diphenyl pyrazole (3,5‐Ph 2 PzH), and 5‐methyl‐3‐phenyl pyrazole (3‐Ph‐5‐Me‐PzH)) followed by treatment with( η 6 ‐benzenecarboxylic acid) chromium tricarbonyl afforded the bimetallic zinc‐chromium complexes [Zn{( η 6 ‐C 6 H 5 COO)Cr(CO) 3 } 2 (3,5‐Me 2 PzH) 2 ], [Zn{( η 6 ‐C 6 H 5 COO)Cr(CO) 3 } 2 (3,5‐ t Bu 2 PzH) 2 ], [Zn{( η 6 ‐C 6 H 5 COO)Cr(CO) 3 } 2 (3,5‐Ph 2 PzH) 2 ], and [Zn{ η 6 ‐C 6 H 5 COO)Cr(CO) 3 } 2 (3‐Ph‐5‐Me‐PzH) 2 ]. The corresponding bimetallic cadmium‐chromium complexes [Cd{( η 6 ‐C 6 H 5 COO)Cr(CO) 3 } 2 (3,5‐Me 2 PzH) 2 ] and [Cd{( η 6 ‐C 6 H 5 COO)Cr(CO) 3 } 2 (3,5‐ t Bu 2 PzH) 2 ] were obtained by using cadmium acetate as starting material. The pyrazole rings and the carboxylate {( η 6 ‐C 6 H 5 COO)Cr(CO) 3 } – anion act as monodentate ligand in the zinc complexes, whereas a monodentate and bidentate coordination of the {( η 6 ‐C 6 H 5 COO)Cr(CO) 3 } – anion is observed in the cadmium complexes.