The dithiooxalate-bridged complex [Cr(C2O2S2)3(NiL)3][ClO4]3(L = racemic 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane): synthesis, crystal structure and magnetism
Abstract
The reaction of KCa[Cr(C2O2S2)3]·6H2O (C2O2S2= dithiooxalate) and [NiL][ClO4]2(L = racemic 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) in the 1:3 molar ratio gave a chromium(III)trinickel(II) complex [Cr(C2O2S2)3(NiL)3][ClO4]3. It crystallizes with two dimethylformamide and two PriOH molecules in the monoclinic space group C2/c, with a= 31.51(1), b= 17.447(6), c= 19.05(1)Å, β= 112.75(4)° and Z= 4. The complex has a CrNi3 core bridged by dithiooxalate groups which bond through sulfur atoms to the Cr and through oxygen atoms to the Ni. The Cr ⋯ Ni separation is 5.959(5)–5.999(6)Å. The CrS6 entity shows a distortion to a trigonal-prismatic geometry. Each nickel ion assumes a pseudo-octahedral geometry with two oxygen atoms of the C2O2S2 group and four nitrogen atoms of L in a folded form. Cryomagnetic studies (4.2–300 K) revealed a ferromagnetic spin-exchange interaction between the CrIII and NiII(J=+5.9 cm–1 based on ℋ=–2ΣJijŠiŠj).