Synthesis, crystal structure and magnetic studies of tetranuclear hydroxo and ligand bridged [Co4(μ3-OH)2(μ2-dea)2(L-L)4]4Cl·8H2O [L-L = 2,2'-bipyridine or 1,10-phenanthroline] complexes with mixed valence defect dicubane core

• Published in: Dalton transactions : an international journal of inorganic chemistry 2013-07, Vol.42 (26), p.9513-9522
• Main Authors: Siddiqi, Zafar A, Siddique, Armeen, Shahid, M, Khalid, Mohd, Sharma, Prashant K, Anjuli, Ahmad, Musheer, Kumar, Sarvendra, Lan, Yanhua, Powell, Annie K
• Format: Article
• Language: English
• Subjects: 2,2'-Dipyridyl - chemistry; Cobalt - chemistry; Crystallography, X-Ray; Ligands; Magnetic Phenomena; Models, Molecular; Molecular Structure; Organometallic Compounds - chemical synthesis; Organometallic Compounds - chemistry; Phenanthrolines - chemistry
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c3dt50854d

X-ray crystallography of the title complexes indicates a discrete mixed valence (Co2(II)-Co2(III)) defect dicubane molecular unit where each cobalt nucleus attains a distorted octahedral geometry. The α-diimine (L-L) chelator coordinated to each cobalt ion stops further polymerization or nuclearization. The water molecules in the lattice play a crucial role in the formation of the supramolecular architectures. Magnetic data were analyzed using the effective spin-1/2 Hamiltonian approach and the parameters are, J = 115(6) K, ΔJ = -57.0(1.2) K, g(xy) = 3.001(25), and g(z) = 7.214(7) for 1 and J = 115(12) K, ΔJ = -58.5(2.5) K, g(xy) = 3.34(5), and g(z) = 6.599(12) for 2 suggesting that only the g matrices are prone to the change of α-diimine chelator.