Copper(I)tris(pyrazolyl)methane complexes and their reactivity towars dioxygen

摘要

The reactivity towards dioxygen has been explored for two copper (I) tris (pyrazolyl)-methane compelxes, [Cu~1((3,5-Me_2-pz)_3CH)](MeCN)](PF_6)_2 (1) and [Cu~1((3,5-Me_2-4-Br-pz)_3)(MeCN)](PF_6)_2 (2). Reversible oxygenation of 1 occurs in CH_2Cl_2 solution at approx 7 deg C to yield a 2:1 #mu#-#eta#~2-#eta#~2-peroxo complex [((3,5-Me_2-pz)_3CH)]Cu(#mu#-O_2)](PF_6)_2. Equilibrium studies, made using manometric techniques over the temperature range 258 -278 K and equilibration times , 2 and 3 min, yielded best-fit thermodynamic constants of K_(21) =32M~(-2) (at 298 K), #delta#H deg =-110+-5K J mol~(-1) , #DELTA#S deg=-340+-18 J K~(-1) mol ~(-1) (30 min) which have been compared to values for other CuO_2 adducts, Thermal decopmposition of this #mu#-peroxo species yields crystals of di-#mu#-hydroxo complex[((3,5-Me_2-pz)_3CH)_2]Cu_2(#mu#-OH)_2](PF_6)_2 (3), whose crystal structure and magnetism (J= -298 cm~(-1) ) are described. Complex 3 and also be made by reaction of 1 with iodosylbenzene, Complex 2 does not form a dioxygen adduct but slowly oxidizes in CH_2Cl_2 to form [Cu(II)((3,5-Me_4-Br-pz)_3CH)_2](PF_6)_2 centre dot 2CH_2Cl_2(4) , the crystal structure of which is described. Complex 4 was also formed by the reation of 2 with iodosylbenzene.