Structures and Spectral Properties of Some Bis(carboxylato)copper(II)-Pyrazole Complexes. I. Preparation of Bis(trifluoroacetato)tetrakis(pyrazole)copper(II)

Abstract

The preparation of several kinds of [Cu(tfa)2(Hpzl)4] (Htfa = trifluoroacetic acid; Hpzl = 1H-pyrazoles) by stoichiometric reactions of [Cu(hfac)2] (Hhfac = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione) with a pyrazole in petroleum ether is reported. As isolable intermediate of this reaction, [Cu(hfac)2(Hpzl)4] was obtained in some cases. The structure of [Cu(tfa)2(4-Hmpz)4] (1e) (4-Hmpz = 4-methyl-1H-pyrazole) has been determined by X-ray analysis. The structures of other [Cu(tfa)2(Hpzl)4] are estimated on the basis of their IR spectra.

Spontaneous Self-Assembly of an Unsymmetric Trinuclear Triangular Copper(II) Pyrazolate Complex, [Cu3(μ3-OH)(μ-pz)3(MeCOO)2(Hpz)] (Hpz = Pyrazole). Synthesis, Experimental and Theoretical Characterization, Reactivity, and Catalytic Activity

“…The two pyrazole rings are tilted with respect to each other [dihedral angle 50.9(5)°] presumably to optimize the aforementioned hydrogen bond in which one of the two rings is engaged. The Cu−O distances [Cu−O(1) = 1.959 Å,Cu−O(3) 1.999(3) Å] are shorter than those found in the square bipyramidal Cu(CF 3 COO) 2 (4-Mepz) 4 [Cu−O = 2.452(3) Å] and slightly longer than those found, for example, in Cu(CF 3 COO) 2 (IMPh) 4 (IMPh = 2-phenyl-4,4,5,5-tetramethyl-4,5-dihydro-1 H -imidazolin-1-oxyl) [Cu−O = 1.948(4) Å] . In the solid-state complex 12 is polymeric and forms infinite zigzag chains (Figure ).…”

Reactions of a Coordination Polymer Based on the Triangular Cluster [Cu3(μ3-OH)(μ-pz)3]2+ with Strong Acids. Crystal Structure and Supramolecular Assemblies of New Mono-, Tri-, and Hexanuclear Complexes and Coordination Polymers

“…The first one, [Cu(CF 3 COO) 2 (Hpz) 4 ], 6 m(a) , previously obtained through a completely different procedure, was only partly characterized. 18 Its crystal structure shows that the Cu II ion has a quite distorted octahedral coordination, with the four pyrazoles occupying the equatorial positions (Figure 8a). While all the Cu-N distances fall in the narrow range from 1.999(2) to 2.029(2) A ˚, the two apical Cu-O distances are quite different [Cu(1)-O(1) 2.381(2) A ˚; Cu(1)-O(3) 2.489(2) A ˚], as well as the angles they form with the equatorial plane (Figure 8b).…”

“…17 Reaction of 1 with CF 3 COOH. Three different compounds were isolated and characterized, [Cu 18 and [Cu(CF 3 COO) 2 (Hpz) 2 ], 6 m(b) . 10a Reaction of 1 with CF 3 SO 3 H. Three different compounds were isolated and characterized, [Cu…”

“…Three different compounds were isolated and characterized, [Cu 3 ( μ 3 -OH)( μ -pz) 3 (CF 3 COO) 2 (Hpz) 2 ], 6 t , [Cu(CF 3 COO) 2 (Hpz) 4 ], 6 m(a) , and [Cu(CF 3 COO) 2 (Hpz) 2 ], 6 m(b)…”

Double half-cubane copper(ii) complexes available from copper(ii) 1,1,1,5,5,5-hexafluoropentane-2,4-dionate dissolved in formamides

“…16 The tfa complexes have sometimes been obtained as an unexpected product from complexation of [M(hfac) 2 ] with the aid of bases. 17, 18 Water comes from the starting material [Cu(hfac) 2 ]•nH 2 O and/or solvents. A possible mechanism for the formation of ttpt includes hydrolysis of hfac and aldol-type condensation of hfac and 1,1,1-trifluoroacetonate (Scheme 2).…”