A series of heteroleptic complexes of the type fac-[MnIIIL2]− [H2L=derivatives of N-(2-hydroxybenzyl)glycine or N-(5-nitro-2-hydroxybenzyl)sarcosine] possessing unusual Mn(III) co-ordination spheres
作者:Musa S. Shongwe、Masahiro Mikuriya、Ryoji Nukada、Eric W. Ainscough、Andrew M. Brodie、Joyce M. Waters
DOI:10.1016/s0020-1693(99)00139-5
日期:1999.7
The mononuclear manganese(III) complexes [C5H10NH2][MnL2] [L2- = a substituted N-(2-hydroxybenzyl)glycinate (hbg(2-)) viz. 3,5-dibromo- (3,5-Br-hbg(2-)), 3,5-dichloro- (3,5-Cl-hbg(2-)), 3-methyl-5-chloro- (3,5-Me,Cl-hbg(2-)), 5-bromo- (5-Br-hbg(2-)), 5-chloro- (5-Cl-hbg(2-)), 5-nitro- (5-NO2-hbg(2-)) or N-(5-nitro-2-hydroxybenzyl)sarcosine (5-NO2-hbs(2-))] have been synthesised by reaction of the appropriate ligand with manganese(II) perchlorate under ambient conditions in a 2:1 molar ratio using piperidine as base. The structures of three of these complexes, [C5H10NH2][Mn(3,5-Cl-hbg)(2)] (2), [C5H10NH2][Mn(5-NO2-hbg)(2)] (6) and [C5H10NH2][Mn(5-NO2-hbs)(2)] (7) have been-elucidated by single-crystal X-ray crystallography and each displays two similar, independent [MnL2](-) ions in the asymmetric unit linked via piperidinium cations through hydrogen bonding. The ligands co-ordinate in a facial tridentate fashion with the three donor atoms being the phenolate and carboxylate oxygens and the amine nitrogen. The geometry at the Mn centres is compressed rhombic octahedral consistent with a pseudo-Jahn-Teller compression along the Mn-O(phenolate) axis. Mean bond lengths are in the ranges 1.886-1.889 Angstrom for the Mn-O(phenolate), 2.062-2.125 Angstrom for the Mn-O(carboxylate) and 2.091-2.184 Angstrom for the Mn-N(amine) distances. The magnetic susceptibility and electronic and IR spectroscopic data are discussed with reference to the crystal structures. (C) 1999 Elsevier Science S.A. All rights reserved.