Synthesis and structural characterization of trinuclear CuII-pyrazolato complexes containing μ3-OH, μ3-O, and μ3-Cl ligands.: Magnetic susceptibility study of [PPN]2[(μ3-O)Cu3(μ-pz)3Cl3]

The nine-membered [-Cu-II-N-N-](3) ring of trimeric copper-pyrazolato complexes provides a sturdy framework on which water is twice deprotonated in consecutive steps, forming mu(3)-OH and mu(3)-O species. In the presence of excess chlorides the mu(3)-O(H) ligand is replaced by two mu(3)-Cl ions. The interconversion of mu(3)-OH and mu(3)-O and the exchange of mu(3)-O(H) and mu(3)-Cl are reversible, and the three species involved have been structurally characterized: [PPN][Cu-3(mu(3)-OH)(mu-pz)(3)Cl-3(thf)].CH2Cl2 (1a), monoclinic P2(1)/n, a = 10.055(2) Angstrom, b = 35.428(5) Angstrom, c = 15.153(2) Angstrom, beta = 93.802(3)degrees, V = 5386(1) Angstrom(3), Z = 4; [BU4N][Cu-3(mu(3)-OH)(mu-pz)(3)Cl-3] (1b), triclinic P-1, a = 9.135(2) Angstrom, b = 13.631(2) Angstrom, c = 14.510(2) Angstrom, alpha = 67.393(2)degrees, beta = 87.979(2)degrees, gamma = 80.268(3)degrees, V = 1643.2(4) Angstrom(3), Z = 2; [PPN](2)[Cu-3(mu(3)-O)(mu-pz)(3)Cl-3] (2), monoclinic P2/c, a = 12.807(2) Angstrom, b = 13.093(2) Angstrom, c = 23.139(4) Angstrom, beta = 105.391(3)degrees, V = 3741(1) Angstrom(3), Z = 2; [PPN](2)[Cu-3(mu(3)-Cl)(2)(mu-pz)(3)Cl-3].0.75H(2)O.0.5CH(2)Cl(2) (3a), triclinic P-1, a = 14.042(2) Angstrom, b = 23,978(4) Angstrom, c = 25.195(4) Angstrom, alpha = 76.796(3)degrees, beta = 79.506(3)degrees, gamma = 77.629(3)degrees, V = 7988(2) Angstrom(3), Z = 4; [Bu4N](2)[Cu-3(mu(3)-Cl)(2)(mu-pz)(3)Cl-3] (3b), monodinic C2/c, a = 17.220(2) Angstrom, b = 15,606(2) Angstrom, c = 20,133(2) A, beta = 103.057(2)degrees, V = 5270(1) Angstrom(3), Z = 4; [Et3NH][Cu-3(mu(3)-OH)(mu-pz)(3)Cl-3(pzH)] (4), triclinic P-1, a = 11.498(2) Angstrom, b = 11.499(2) Angstrom, c = 12.186(2) Angstrom, alpha = 66.475(3)degrees, beta = 64.279(3)degrees, gamma = 80.183(3)degrees, V = 1331.0(5) Angstrom(3), Z = 2. Magnetic susceptibility measurements show that the three copper centers of 2 are strongly antiferromagnetically coupled with J(Cu-Cu) = -500 cm(-1).