title: Tuning of exchange coupling by the Mn-O distance and phenoxido bridging angle: an experimental and theoretical study of the family of Mn(iii) dimers with salen type ligands.
abstract: Three new Mn(III) complexes [Mn2L2(ClO4)2] (1), [Mn2L2(NCS)2] (2) and [Mn2L2N(CN)2]ClO4·CH3CN (3) have been synthesized from the Schiff base ligand H2L (where H2L = N,N′-bis(2-hydroxypropiophenone)-1,2- ethanediamine) and various anionic coligands e.g. perchlorate, thiocyanate and dicyanamide. X-ray crystal structure analysis reveals that 1 and 2 are dinuclear complexes, joined together by Mn⋯O (phenoxido) interactions. Whereas 3 consists of an alternating phenoxido and μ1,5 dicyanamido bridge, resulting in a 1D chain. In 1 and 2 ferromagnetic coupling exists between the Mn(III) centres within the dimer but 3 possesses antiferromagnetic interaction. This difference in magnetic exchange interactions has been rationalized on the basis of structural parameters like longer bridging Mn-O distance and Mn-O-Mn angle in these complexes with the help of DFT calculations.
authors.affiliation: Department of Chemistry, University College of Science, University of Calcutta, 92, A.P.C. Road, Kolkata 700 009, India. ghosh_59@yahoo.com.
authors.forename: Piya
authors.initials: P
authors.lastname: Seth
authors.forename: Sanjib
authors.initials: S
authors.lastname: Giri
authors.forename: Ashutosh
authors.initials: A
authors.lastname: Ghosh