Synthese, Struktur und EPR‐Untersuchungen von binuklearen Bis(N,N,N‴,N‴‐tetraisobutyl‐N′,N″‐isophthaloylbis(thioureato))‐Komplexen des CuII, NiII, ZnII, CdII und PdII

• Published in: Zeitschrift für anorganische und allgemeine Chemie (1950) Vol. 634; no. 5; pp. 867 - 874
• Main Authors: Rodenstein, Axel, Griebel, Jan, Richter, Rainer, Kirmse, Reinhard
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY‐VCH Verlag 01.05.2008
• Subjects: Binuclear metal(II) complexes; Crystal structures; EPR investigations; Quadridentate N‐acylbis(thiourea)
• ISSN: 0044-2313; 1521-3749
• DOI: 10.1002/zaac.200700513

Synthesis, Structure and EPR Investigations of binuclear Bis(N,N,N‴,N‴‐tetraisobutyl‐N′,N″‐isophthaloylbis(thioureato)) Complexes of CuII, NiII, ZnII, CdII and PdII The synthesis of binuclear CuII‐, NiII‐, ZnII‐, CdII‐ and PdII‐complexes of the quadridentate ligand N,N,N‴,N‴‐tetraisobutyl‐N′,N″‐isophthaloylbis(thiourea) and the crystal structures of the CuII‐ and NiII‐complexes are reported. The CuII‐complex crystallizes in two polymorphic modifications: triclinic, $P{\bar 1}$ (Z = 1) and monoclinic, P21/c (Z = 2). The NiII‐complex was found to be isostructural with the triclinic modification of the copper complex. The also prepared PdII‐, ZnII‐ and CdII‐complexes could not be characterized by X‐ray analysis. However, EPR studies of diamagnetically diluted CuII/PdII‐ and CuII/ZnII‐powders show axially‐symmetric g and ACu tensors suggesting a nearly planar co‐ordination within the binuclear host complexes. Diamagnetically diluted CuII/CdII powder samples could not be prepared. In the EPR spectra of the pure binuclear CuII‐complex exchange‐coupled CuII‐CuII pairs were observed. According to the large CuII‐CuII distance of about 7,50Å a small fine structure parameter D = 26·10−4 cm−1 is observed; T‐dependent EPR measurements down to 5 K reveal small antiferromagnetic interactions for the CuII‐CuII dimer. Besides of the dimer in the EPR spectra the signals of a mononuclear CuII species are observed whose concentration is T‐dependent. This observation can be explained assuming an equilibrium between the binuclear CuII‐complex (CuII‐CuII pairs) and oligomeric complexes with “isolated” CuII ions.