A NOVEL PENTADENTATE COORDINATION MODE FOR THE CARBONATE BRIDGE - SYNTHESIS, CRYSTAL STRUCTURE, AND MAGNETIC BEHAVIOR OF (MU(3)-CO3)[NI-3(MEDPT)(3)(NCS)(4)], A NEW TRINUCLEAR NICKEL(II) CARBONATE-BRIDGED COMPLEX WITH STRONG ANTIFERROMAGNETIC COUPLING

摘要

The trinuclear complex (mu(3)-CO3)[Ni-3(Medpt)(3)(NCS)(4)] was obtained by reaction of basic solutions of nickel(II), Medpt (bis(3aminopropyl)methylamine) and thiocyanate ligand with atmospheric CO2 or by simple reaction with carbonate anion. (mu(3)-CO3)[Ni-3(Medpt)(3)(NCS)(4)] crystallizes in the triclinic system, space group , with a = 12.107(5) Angstrom, b = 12.535(7) Angstrom, c = 16.169(9) Angstrom, alpha = 102.69(5)degrees, beta = 92.91(5)degrees, gamma = 118.01(4)degrees, Z = 2, and R = 0.043. The three nickel atoms are asymmetrically bridged by one pentadentate carbonate ligand, which shows a novel coordination mode. The (mu(3)-CO3)[Ni-3(Medpt)(3)(NCS)(4)] compound shows a very strong antiferromagnetic coupling. Fit as irregular triangular arrangement gave J(1) = -88.4, J(2) = -57.7, and J(3) = -9.6 cm(-1), which is the strongest AF coupling observed to date for Ni-3 compounds. The magnetic behavior of the carbonate bridge is discussed. [References: 40]