Synthesis, Crystal Structure and Magnetic Properties of a Trinuclear Copper(II) Complex Based on P-Cresol-Substituted Bis(alpha-Nitronyl Nitroxide) Biradical

Trinuclear copper(II) complex [Cu-3(II)(NIT2PhO)(2)Cl-4] was synthesized with p-cresol-substituted bis(alpha-nitronyl nitroxide) biradical: 4-methyl-2,6-bis(1-oxyl-3-oxido-4,4,5,5-tetramethyl-2-imidazolin-2-yl)phenol (NIT2PhOH). The crystal structure of this heterospin complex was determined using single-crystal X-ray diffraction analysis and exhibits four unusual seven-membered metallocycles formed from the coordination of oxygen atoms of the N-O groups and of bridging phenoxo (mu-PhO-) moieties with copper(II) ions. The crystal structure analysis reveals an incipient agostic interaction between a square planar copper center and a hydrogen-carbon bond from one methyl group carried on the coordinated nitronyl-nitroxide radical. The intramolecular Cu center dot center dot center dot H-C interaction involves a six-membered metallocycle and may stabilize the copper center in square planar coordination mode. From the magnetic susceptibility measurements, the complex, which totals seven S = 1/2 spin carriers, has almost a ground state spin S = 1/2 at room temperature ascribed to strong antiferromagnetic interaction between the nitronyl nitroxide moieties and the copper(II) centers and in between the copper(II) centers through the bridging phenoxo oxygen atom.

Automated summary

A novel trinuclear copper(II) complex was synthesized, with an unusual crystal structure featuring seven-membered metallocycles and an agostic interaction between a copper center and a hydrogen-carbon bond. Magnetic susceptibility measurements indicate strong antiferromagnetic interactions in the complex.