title: Unique asymmetric (CuII4) double-stranded helicate from a hexadentate piperazine-based ligand: ligand conformation isomerism upon coordination.
abstract: In methanol, the reaction of Cu(ClO(4))(2).6H(2)O and a sterically constrained piperazine imine phenol ligand (H(2)L), in the presence of NEt(3), affords a novel tetranuclear copper(II) complex of formula [Cu(II)(4)(mu(3)-L)(2)(mu-OH)(2)(H(2)O)(2)](ClO(4))(2).H(2)O (1). The X-ray structure of this complex shows an elongated Cu(4) quasi-tetrahedron coordinated to two hexadentate chair-(e,a)-mu(3)-piperazine bridging ligands. Variable-temperature magnetic studies show an S(t) = 0 spin ground state resulting from antiferromagnetic interactions between Cu(II) ions within the complex.
authors.affiliation: Department of Chemistry, Indian Institute of Technology, Kharagpur 721 302, India.
authors.forename: Alok Ranjan
authors.initials: AR
authors.lastname: Paital
authors.forename: Prasant Kumar
authors.initials: PK
authors.lastname: Nanda
authors.forename: Sunirban
authors.initials: S
authors.lastname: Das
authors.forename: Guillem
authors.initials: G
authors.lastname: Aromí
authors.forename: Debashis
authors.initials: D
authors.lastname: Ray
mesh_terms: D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008024:Ligands; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D010879:Piperazines / Q000737:chemistry*; D013237:Stereoisomerism; D013696:Temperature
chemical_list: D008024:Ligands; D009942:Organometallic Compounds; D010879:Piperazines; D003300:Copper