Issue 26, 2011

Homoleptic 1-D iron selenolate complexes—synthesis, structure, magnetic and thermal behaviour of 1[Fe(SeR)2] (R = Ph, Mes)

Abstract

The first examples of polymeric homoleptic iron chalcogenolato complexes 1[Fe(SePh)2] and 1[Fe(SeMes)2] (Ph = phenyl = C6H5, Mes = mesityl = C6H2-2,4,6-(CH3)3) have been both prepared by reaction of [Fe(N(SiMe3)2)2] with two equivalents of HSeR (R = Ph, Mes) while 1[Fe(SePh)2] was found to be also easily accessible through reactions of either FeCl2, Fe(OOCCH3)2 or FeCl3 with PhSeSiMe3 in THF. In the crystal, the two compounds form one-dimensional chains with bridging selenolate ligands comprising distinctly different Fe–Se–Fe bridging angles, namely 71.15–72.57° in 1[Fe(SePh)2] and 91.80° in 1[Fe(SeMes)2]. Magnetic measurements supported by DFT calculations reveal that this geometrical change has a pronounced influence on the antiferromagnetic exchange interactions of the unpaired electrons along the chains in the two different compounds with a calculated magnetic exchange coupling constant of J = −137 cm−1 in 1[Fe(SePh)2] and J = −20 cm−1 in 1[Fe(SeMes)2]. In addition we were able to show that the ring molecule [Fe(SePh)2]12 which is a structural isomer of 1[Fe(SePh)2] behaves magnetically similar to the latter one. Investigations by powder XRD reveal that the ring molecule is only a metastable intermediate which converts in THF completely to form 1[Fe(SePh)2]. Thermal gravimetric analysis of 1[Fe(SePh)2] under vacuum conditions shows that the compound is thermally labile and already starts to decompose above 30 °C in a two step process under cleavage of SePh2 to finally form at 250 °C tetragonal PbO-type FeSe. The reaction of 1[Fe(SePh)2] with the Lewis base 1,10-phenanthroline yielded, depending on the conditions, the octahedral monomeric complexes [Fe(SePh)2(1,10-phen)2] and [Fe(1,10-phen)3][Fe(SePh)4].

Graphical abstract: Homoleptic 1-D iron selenolate complexes—synthesis, structure, magnetic and thermal behaviour of 1∞[Fe(SeR)2] (R = Ph, Mes)

Supplementary files

Article information

Article type
Paper
Submitted
17 Jan 2011
Accepted
12 Apr 2011
First published
02 Jun 2011

Dalton Trans., 2011,40, 7022-7032

Homoleptic 1-D iron selenolate complexes—synthesis, structure, magnetic and thermal behaviour of 1[Fe(SeR)2] (R = Ph, Mes)

A. Eichhöfer, G. Buth, F. Dolci, K. Fink, Richard. A. Mole and P. T. Wood, Dalton Trans., 2011, 40, 7022 DOI: 10.1039/C1DT10089K

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