Ferro- and Antiferromagnetic Coupling through 1,n-Dithiosquarate Bridges (n = 2, 3) in Copper(II) Dimers. Syntheses, Crystal Structures, and Magnetic Properties of [Cu(2)(bpca)(2)(1,2-dtsq)(H(2)O)].2H(2)O and [Cu(2)(bpca)(2)(1,3-dtsq)].2H(2)O

Isabel Castro; María Luisa Calatayud; Jorunn Sletten; Francesc Lloret; Juan Cano; Miguel Julve; Gunther Seitz; Klaus Mann

doi:10.1021/ic9904384

Ferro- and Antiferromagnetic Coupling through 1,n-Dithiosquarate Bridges (n = 2, 3) in Copper(II) Dimers. Syntheses, Crystal Structures, and Magnetic Properties of [Cu(2)(bpca)(2)(1,2-dtsq)(H(2)O)].2H(2)O and [Cu(2)(bpca)(2)(1,3-dtsq)].2H(2)O

Inorg Chem. 1999 Oct 18;38(21):4680-4687. doi: 10.1021/ic9904384.

Authors

Isabel Castro¹, María Luisa Calatayud, Jorunn Sletten, Francesc Lloret, Juan Cano, Miguel Julve, Gunther Seitz, Klaus Mann

Affiliation

¹ Departament de Química Inorgànica, Facultat de Química, Universitat de València, Dr. Moliner 50, 46100 Burjassot, València, Spain, Kjemisk Institutt, Universitetet i Bergen, 5007 Bergen, Norway, and Abteilung Pharmazeutische Chemie, Philipps-Universität Marburg, Marbacher Weg 6, 35032 Marburg, Germany.

PMID: 11671191
DOI: 10.1021/ic9904384

Abstract

The preparation, crystal structures, and variable-temperature magnetic susceptibility data for two dithiosquarate-bridged copper(II) complexes of formulas [Cu(2)(bpca)(2)(1,2-dtsq)(H(2)O)].2H(2)O (1) and [Cu(2)(bpca)(2)(1,3-dtsq)].2H(2)O (2) (where bpca = the bis(2-pyridylcarbonyl)amide anion, 1,2-dtsq = dianion of 3,4-dimercapto-3-cyclobutene-1,2-dione, and 1,3-dtsq = dianion of 3-hydroxy-4-mercapto-2-thioxo-3-cyclobuten-1-one) are reported herein. 1 and 2 crystallize in the triclinic system, space group P&onemacr;, with a = 9.3243(4) Å, b = 10.9036(5) Å, c = 15.5432(4) Å, alpha = 90.276(2) degrees, beta = 100.009(2) degrees, gamma = 94.139(2) degrees, and Z = 2 for 1 and a = 7.656(2) Å, b = 9.351(3) Å, c = 11.587(2) Å, alpha = 109.02(2) degrees, beta = 97.40(2) degrees, gamma = 110.27(2) degrees, and Z = 1 for 2. Their structures consist of the neutral dithiosquarate-bridged copper(II) units [Cu(2)(bpca)(2)(1,2-dtsq)(H(2)O)] (1) and [Cu(2)(bpca)(2)(1,3-dtsq)] (2) and water molecules of crystallization. The copper environment is distorted square pyramidal CuN(3)SO in both compounds. Bpca acts as a tridentate end-cap ligand with its three nitrogen atoms occupying three of the four basal positions. 1,3-Dithiosquarate adopts a centrosymmetric bis-bidentate bridging mode with the sulfur atom filling the fourth equatorial position around each copper atom and the oxygen at the apical site. 1,2-Dithiosquarate acts also as a bridging ligand but in an asymmetrical manner, chelating through the two sulfur atoms at one copper atom and unidentate through one sulfur at the other copper atom. The bridging sulfur occupies one equatorial position at a copper atom and the apical site at the other one. The metal-metal separations through the extended 1,2- and 1,3-dtsq bridges are 5.1654(8) and 7.212(3) Å, respectively. The exchange pathways accounting for the intermediate ferro- (1, J = +32.4 cm(-)(1)) and antiferromagnetic (2, J = -33.5 cm(-)(1)) couplings (H = -JS(A).S(B)) observed in these dithiosquarate-bridged compounds are analyzed and discussed in the light of density functional theory (DFT) calculations.