Preparation and characterisation of bis(1,1,1,5,5,5-hexafluoropentane-2,4-dionato)copper(II) complexes with diazaaromatic compounds. Part 1. Crystal structures and characterisation of several adducts with diazines

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The reactions of [Cu(hfac)2](Hhfac = 1,1,1,5,5,5-hexafluoropentane-2,4-dione) with diazines (tmpyz = 2,3,5-trimethylpyrazine, mpym = 5-methylpyrimidine and mpydz = 3-methylpyridazine) in light petroleum have been studied and the following complexes obtained: [{Cu(hfac)2}3(µ-tmpyz)2]1b, [Cu(hfac)2(tmpyz)]1e, [{Cu(hfac)2(µ-mpym)n}]2a, [{Cu(hfac)2}3(µ-mpym)2]2b, [{Cu(hfac)2}2(µ-mpym)]2c, [Cu(hfac)2(mpym)2]2d, and [Cu(hfac)2(mpydz)2]3d. The crystal structures of 1b, 2b and 3d have been determined. Although 1b and 2b are both trinuclear complexes with bridging diazole molecules, the geometry around atom Cu(2) is trigonal bipyramidal for 1b and tetragonal pyramidal for 2b. The geometry around atom Cu(1) is tetragonal bipyramidal in both complexes. The distance Cu(1)–N(1) is longer in 1b than in 2b, while the Cu(2)–N(2) is somewhat shorter in the former. The steric effects of the ligands on the structural differences between these complexes are discussed. On the basis of the relation between the geometry of the co-ordinated hfac ligands and ν(C–O) values, structures of some of the other complexes are suggested.