TY - JOUR
T1 - Dinuclear and tetranuclear copper(II) complexes with bridging (N-N) diazine ligands
T2 - Variable magnetic exchange topologies
AU - Xu, Zhiqiang
AU - Thompson, Laurence K.
AU - Matthews, Craig J.
AU - Miller, David O.
AU - Goeta, Andrés E.
AU - Wilson, Claire
AU - Howard, Judith A.K.
AU - Ohba, Masaaki
AU - Okawa, Hisashi
PY - 2000
Y1 - 2000
N2 - Dinuclear and tetranuclear copper(II) complexes of three polydentate diazine ligands (pahap, pmhap, bdpah), based on potentially bridging N-N single bond fragments, are reported. The 2:2 complexes [Cu2(pahap)2(NO3)(H2O) 2][NO3]3·H2O (1) and [Cu2(pmhap)2(NO3)2[NO 3]2·3H2O (2) involve dinuclear centres bridged by two N-N single bonds, and are essentially uncoupled, as a result of strict orbital orthogonality or an acute twisting of the copper magnetic planes relative to the N-N bridge. A mixed, double bridged (pyridazine/N-N) complex [Cu2(pahap)(dppn)(NO3)(H2O)][NO 3]3 (3) has a larger angle between the magnetic planes, resulting in weak antiferromagnetic behaviour (2J= -32.5 cm-1). The rotationally more flexible 1:1 complexes [Cu2(pahap)(C2O4)2]·0.5H 2O (4) (2J= -4.4 cm-1) and [Cu2(pahap)(acac)2(H2O)2][NO 3]2·H2O (5) (2J= -69.7 cm-1) involve single N-N bridges, and the angle between the copper magnetic planes depends on steric factors and hydrogen bonding interactions respectively. A tetranuclear complex [Cu2(pahap - H)(dpa)]2[NO3]4·4H2O (6) results from the linking of two {Cu2(N-N)} subunits with a secondary ligand strap, 1,3-diamino-2-propanol, and leads to a trans Cu2(N-N) bridging arrangement and strong antiferromagnetic coupling (2J= -186.4 cm-1). The complex [Cu2(bdpah - H)(NO3)2][NO3] (7) has a locked conformation with a large Cu-N-N-Cu torsional angle (130.3°), leading to moderately strong antiferromagnetic coupling (2J= -112.0 cm-1). The magnetic results are entirely consistent with previous magnetostructural correlations relating the twist of the copper magnetic planes around the N-N bond to the exchange integral.
AB - Dinuclear and tetranuclear copper(II) complexes of three polydentate diazine ligands (pahap, pmhap, bdpah), based on potentially bridging N-N single bond fragments, are reported. The 2:2 complexes [Cu2(pahap)2(NO3)(H2O) 2][NO3]3·H2O (1) and [Cu2(pmhap)2(NO3)2[NO 3]2·3H2O (2) involve dinuclear centres bridged by two N-N single bonds, and are essentially uncoupled, as a result of strict orbital orthogonality or an acute twisting of the copper magnetic planes relative to the N-N bridge. A mixed, double bridged (pyridazine/N-N) complex [Cu2(pahap)(dppn)(NO3)(H2O)][NO 3]3 (3) has a larger angle between the magnetic planes, resulting in weak antiferromagnetic behaviour (2J= -32.5 cm-1). The rotationally more flexible 1:1 complexes [Cu2(pahap)(C2O4)2]·0.5H 2O (4) (2J= -4.4 cm-1) and [Cu2(pahap)(acac)2(H2O)2][NO 3]2·H2O (5) (2J= -69.7 cm-1) involve single N-N bridges, and the angle between the copper magnetic planes depends on steric factors and hydrogen bonding interactions respectively. A tetranuclear complex [Cu2(pahap - H)(dpa)]2[NO3]4·4H2O (6) results from the linking of two {Cu2(N-N)} subunits with a secondary ligand strap, 1,3-diamino-2-propanol, and leads to a trans Cu2(N-N) bridging arrangement and strong antiferromagnetic coupling (2J= -186.4 cm-1). The complex [Cu2(bdpah - H)(NO3)2][NO3] (7) has a locked conformation with a large Cu-N-N-Cu torsional angle (130.3°), leading to moderately strong antiferromagnetic coupling (2J= -112.0 cm-1). The magnetic results are entirely consistent with previous magnetostructural correlations relating the twist of the copper magnetic planes around the N-N bond to the exchange integral.
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U2 - 10.1039/a907390f
DO - 10.1039/a907390f
M3 - Article
AN - SCOPUS:0009831070
SN - 1470-479X
SP - 69
EP - 77
JO - Journal of the Chemical Society, Dalton Transactions
JF - Journal of the Chemical Society, Dalton Transactions
IS - 1
ER -