Discrete and Monodimensional Heteropolynuclear Structures Formed by Tetracarboxylatodiruthenium(II,III) and Perrhenato Fragments
dataset
posted on 2005-08-08, 00:00 authored by Gema Arribas, M. Carmen Barral, Rodrigo González-Prieto, Reyes Jiménez-Aparicio, J. Luis Priego, M. Rosario Torres, Francisco A. UrbanosReaction between cationic units of carboxylate-bridged diruthenium complexes [Ru<sub>2</sub>(μ-O<sub>2</sub>CR)<sub>4</sub>]<sup>+</sup> (R = Me, CMePh<sub>2</sub>,
CMe<sub>3</sub>, CH<sub>2</sub>CH<sub>2</sub>OMe, C(Me)CHEt, C<sub>6</sub>H<sub>4</sub>-<i>p</i>-OMe, Ph) and tetrabutylammonium perrhenate gives complexes with
different arrangements in the solid state. Thus, the compounds Ru<sub>2</sub>(μ-O<sub>2</sub>CR)<sub>4</sub>(ReO<sub>4</sub>) [R = Me (<b>1</b>), CMePh<sub>2</sub> (<b>2</b>),
CMe<sub>3</sub> (<b>3</b>), CH<sub>2</sub>CH<sub>2</sub>OMe (<b>4</b>), C(Me)CHEt (<b>5</b>), C<sub>6</sub>H<sub>4</sub>-<i>p</i>-OMe (<b>6</b>), Ph (<b>7</b>)] have polymeric structures with the diruthenium
units linked by perrhenate ligands in the axial positions. The structures of complexes <b>3</b>·THF and <b>4</b> were established
by single-crystal X-ray diffraction. The tetrahedral geometry of the ReO<sub>4</sub><sup>-</sup> anion permits the formation of a chain
close to the linearity. In contrast to the polymeric chains observed in complexes <b>1</b>−<b>7</b>, the reaction of [Ru<sub>2</sub>(μ-O<sub>2</sub>CPh)<sub>4</sub>]<sup>+</sup> with NBu<sub>4</sub>ReO<sub>4</sub> also affords the compounds Ru<sub>2</sub>(μ-O<sub>2</sub>CPh)<sub>4</sub>(ReO<sub>4</sub>)(H<sub>2</sub>O) (<b>8</b>) and NBu<sub>4</sub>[Ru<sub>2</sub>(μ-O<sub>2</sub>CPh)<sub>4</sub>(ReO<sub>4</sub>)<sub>2</sub>] (<b>9</b>) depending on the reaction conditions. The structure of <b>8</b> consists of cationic and anionic units, [Ru<sub>2</sub>(μ-O<sub>2</sub>CPh)<sub>4</sub>(H<sub>2</sub>O)<sub>2</sub>]<sup>+</sup> and [Ru<sub>2</sub>(μ-O<sub>2</sub>CPh)<sub>4</sub>(ReO<sub>4</sub>)<sub>2</sub>]<sup>-</sup>, linked by hydrogen bonds, which give a three-dimensional net.
The structure of complex <b>9</b>·0.5H<sub>2</sub>O has an anionic unit similar to that of <b>8</b>, whose counterion is NBu<sub>4</sub><sup>+</sup>. The Ru−Ru
bond distances are slightly longer in [Ru<sub>2</sub>(μ-O<sub>2</sub>CPh)<sub>4</sub>(ReO<sub>4</sub>)<sub>2</sub>]<sup>-</sup> than in the polymeric compounds Ru<sub>2</sub>(μ-O<sub>2</sub>CR)<sub>4</sub>(ReO<sub>4</sub>). The magnetic behavior owes to the existence of zero-field splitting (ZFS) and a weak antiferromagnetic
coupling. The experimental data are fitted with a model that considers the ZFS effect using the Hamiltonian <i><sub>D</sub></i> =
<i>SDS</i>. The weak antiferromagnetic coupling is introduced as a perturbation, using the molecular field approximation.
