Synproportionation reactions between copper(II) trihalogenoacetates Cu(CX3CO2)2, X = F, Cl or Br, and copper in the presence of carbon monoxide
Abstract
The trichloro- and tribromo-acetato derivatives of copper(II) of general formula Cu2(CX3CO2)4(CX3CO2H)2 have been prepared by exchange reactions from Cu(CF3CO2)2 and CX3CO2H (X = Cl or Br) in a hydrocarbon solvent. The chloro derivative, which has also been obtained from CuO in the presence of CCl3CO2H/(CCl3CO)2O, has been characterized by variable-temperature magnetic measurements and by X-ray diffraction. The trifluoroacetato carbonyl derivative of copper(I), Cu(CF3CO2)(CO), has been prepared: (a) by reaction of Cu2O with CF3CO2H/(CF3CO)2O in the presence of CO; (b) by direct carbonylation of Cu(CF3CO2) in toluene or in the solid state; (c) by synproportionation of Cu(CF3CO2)2 and copper in the presence of CO in MeOH, DME, THF or toluene at room temperature. Solutions of Cu(CCl3CO2)(CO) have been obtained by the synproportionation of Cu2(CCl3CO2)4(CCl3CO2H)2 and copper under a CO atmosphere in toluene. No carbonyl derivative was observed in solution with Cu2(CBr3CO2)4(CBr3CO2H)2 under similar conditions. On standing, hydrocarbon solutions of Cu(CCl3CO2)(CO) slowly gave CuCl(CO) and a mixed-valence, polynuclear carbonyl derivative of formula [Cu4(CCl3CO2)6(CHCl2CO2H)(CO)2]n which has fully been characterized by variable temperature magnetic measurements and by X-ray diffraction.