Some new dinuclear rhodium compounds: preparations and structures

Versatile coordination chemistry of rhodium complexes containing the bis(trimethylsilylmethyl)tellane ligand

“…The Rh1-Cl5 and Rh1-Cl6 bonds that are in trans-positions to tellurium atoms show lengths of 2.417(2) and 2.424(2) Å, respectively, while Rh2-Cl5 and Rh2-Cl6 that are in trans-positions to chlorine show slightly shorter lengths of 2.380(2) and 2.369(2) Å, respectively. All Rh-Cl distances are consistent with those reported for related [Rh 2 (l-Cl) 2 Cl 4 (PR 3 ) 4 ] (R = Et, n Bu) complexes [21].…”

“…Similar structures have been reported for [Rh 2 (l-X) 2 X 4 (PR 3 ) 4 ] (X = Cl, Br; R = Et, n Bu) containing phosphine ligands [21,22]. The isomerism of the dinuclear complexes was rationalized by Cotton et al [21], who concluded that the preferred isomers obeyed two principles: (1) no l-ligand should have both of its bonds weakened by the strong trans-influence of the phosphine ligand, and (2) for steric reasons two phosphine ligands should not occupy adjacent axial positions on the two rhodium atoms.…”

“…The isomerism of the dinuclear complexes was rationalized by Cotton et al [21], who concluded that the preferred isomers obeyed two principles: (1) no l-ligand should have both of its bonds weakened by the strong trans-influence of the phosphine ligand, and (2) for steric reasons two phosphine ligands should not occupy adjacent axial positions on the two rhodium atoms. However, cis-cis arrangement has been reported for [Rh 2 (l-Br) 2 Br 4 (PMe 3 ) 4 ] with sterically less demanding PMe 3 ligands [29].…”

“…The first step involves the formal condensation of the mononuclear [RhCl 3 (OH 2 ) 3 ] complexes into dinuclear chlorido-bridged complexes [28], and the second step involves the ligand substitution of aqua ligands either by tellane or ethanol 2½RhCl 3 ðOH 2 Þ 3 ½Rh 2 ðl-ClÞ 2 Cl 4 ðOH 2 Þ 4 þ 2H 2 O ½Rh 2 ðl-ClÞ 2 Cl 4 ðOH 2 Þ 4 þ 4L ½Rh 2 ðl-ClÞ 2 Cl 4 L 4 þ 4H 2 O By using the argumentation of Cotton et al [21], there are nine possible isomers of [Rh 2 (l-Cl) 2 Cl 4 (OH 2 ) 4 ] assuming that the oxidation state of both rhodium centers is +III. Their formation from mer-and fac-isomers of [RhCl 3 (OH 2 ) 3 ] is shown in Fig.…”

Hydrido, Halo, and Hydrido-Halo Complexes of Two-Electron Mixed-Valence Diiridium Cores

“…Pairing the odd electron in the d z 2 orbital of the two 17 e - Rh 0 and Rh II centers leads to a formal metal−metal bond and a 36 e - species. This formulation of two-electron mixed-valency is differentiated from the common structural motif that is exemplified by 34 e - bimetallic compounds of cobalt, rhodium, and iridium. − Here, single-atom, anionic ligands such as chlorine, oxygen, or sulfur bridge 18 e - octahedral and 16 e - square planar metal centers of a binuclear metal core…”