Four copper(ii) pyrazolido complexes derived from reactions of 3{5}-substituted pyrazoles with CuF2 or Cu(OH)2??

Dalton Transactions Pub Date: 2007-03-09 DOI: 10.1039/B618780C

Abstract

Treatment of CuF2 with 2 equiv of 3{5}-[pyrid-2-yl]pyrazole (HpzPy), 3{5}-phenylpyrazole (HpzPh) or 3{5}-[4-fluorophenyl]pyrazole (HpzPhF) in MeOH, followed by evaporation to dryness and recrystallisation of the solid residues, allows solvated crystals of [{Cu(μ-pzPy)(pzPy)}2] (1), [{Cu(μ-pzPh)2}4] (2) and [Cu4F2(μ4-F)(μ-pzPhF)5(HpzPhF)4] (3) to be isolated in moderate-to-good yields. Similar reactions of these three pyrazoles with Cu(OH)2 in refluxing MeOH respectively afford 1, 2 and [Cu(pzPhF)2(HpzPhF)2] (4) in ca. 10% yield. Crystalline 1·1/2H2O·2CHCl3 contains two independent dinuclear molecules with a puckered di-(1,2-pyrazolido) bridge motif, linked by a bridging, hydrogen-bonding water molecule. Compound 2·1/2C5H12, containing cyclic, square tetranuclear complex molecules, is the first homoleptic divalent metal pyrazolide to have a discrete molecular rather than polymeric structure, for a metal other than Pd or Pt. The two independent complex molecules in 3·3/4CH2Cl2·HpzPhF contain a unique tetrahedral [Cu4(μ4-F)]7+ core, three of whose edges are spanned by bridging pyrazolido groups. Magnetic data show that the copper centres in 1 and 3 are antiferromagnetically coupled, but that dried bulk samples of 2 do not retain their molecular structure.

Graphical abstract: Four copper(ii) pyrazolido complexes derived from reactions of 3{5}-substituted pyrazoles with CuF2 or Cu(OH)2
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