Issue 4, 2002

Syntheses, crystal structures and magnetic properties of copper(ii) dicyanamide complexes; dinuclear, chain and ladder compounds

Abstract

The preparation, crystal structures and magnetic properties of three heteroleptic copper(II) complexes with dicyanamide (dca) bridges, [Cu(bpca)(H2O)(dca)]2 (1) (bpca = bis(2-pyridylcarbonyl)amidate), [Cu(bpy)(dca)2]n (2) (bpy = 2,2′-bipyridine), [Cu2(bpm)(dca)4]n (3) (bpm = 2,2′-bipyrimidine) are reported. In addition, magnetic susceptibility measurements of the sheetlike polymer [Cu(phen)(dca)2] (4) (phen = 1,10-phenanthroline), structurally characterized previously, have been performed. In complex 1 pairs of mononuclear structural building blocks, [Cu(bpca)(dca)(H2O)], are loosely connected through a 1,3-dca bridge in which nitrile is equatorially bound and the amide is semi-coordinated in axial position to copper. The bis-monodentate 1,3-bridging mode of dca has been postulated, but not previously observed. A chain structure is present in 2, one of the dca units serving as an end-to-end out-of-plane bridging ligand, while the other dca is terminal, monodentate. The chain structure is very similar to that found in 4, but while the chains in 4 are connected, forming sheets, this is not so in 2. Compound 3 forms a ladder-like polynuclear structure in which the rungs are formed by bis-chelating bpm bridges and the uprights by end-to-end bridging dca units. The copper⋯copper separations across the dca bridges are 5.732(2) Å (1), 8.1999(8) Å (2) and 7.5550(2) Å (3), respectively, and 5.5673(4) Å across the bpm bridge (3). These values are to be compared with the intrasheet copper⋯copper separations of 7.3002(7) Å (through a single end-to-end dca bridge) and 7.7079(4) Å (through a double end-to-end dca bridge) in 4. Variable-temperature magnetic susceptibility measurements reveal Curie law behaviour with no detectable magnetic coupling in compounds 1 and 2, a very weak ferromagnetic interaction across the single end-to-end dca bridge in 4 (J = +0.2(1) cm−1), and a strong antiferromagnetic interaction across the bpm bridge in compound 3 (J = −211(1) cm−1).

Graphical abstract: Syntheses, crystal structures and magnetic properties of copper(ii) dicyanamide complexes; dinuclear, chain and ladder compounds

Supplementary files

Article information

Article type
Paper
Submitted
05 Jul 2001
Accepted
14 Nov 2001
First published
28 Jan 2002

J. Chem. Soc., Dalton Trans., 2002, 566-574

Syntheses, crystal structures and magnetic properties of copper(II) dicyanamide complexes; dinuclear, chain and ladder compounds

B. Vangdal, J. Carranza, F. Lloret, M. Julve and J. Sletten, J. Chem. Soc., Dalton Trans., 2002, 566 DOI: 10.1039/B105981P

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