71647-01-3Relevant academic research and scientific papers
Binuclear rhodium complexes: Their chemistry with sulfur dioxide and the structure of [Rh2Cl2(μ-SO2)((C6H 5)2PCH2P(C6H5) 2)2]
Cowie, Martin,Dwight, Stephen K.
, p. 209 - 216 (2008/10/08)
The "A-frame" complex [Rh2(CO)2(μ-Cl)(DPM)2][B(C6H 5)4] (DPM = (C6H5)2PCH2P(C6H 5)2) undergoes a facile and reversible reaction with SO2 to yield [Rh2(CO)2(μ-Cl)(μ-SO2)(DPM) 2][B(C6H5)4]. Spectroscopic studies have shown that SO2 attack occurs directly at the bridging site of the "A-frame" complex. Treatment of a solution of the SO2 adduct with excess SO2 in the presence of chloride ion yields a second SO2 complex, [Rh2Cl2(μ-SO2)(DPM)2], the structure of which is reported. In the absence of chloride ion, formation of the second SO2 complex occurs in the presence of small amounts of [RhCl2(CO)2]- with the latter functioning as a chloride-transfer agent. Treatment of the second, SO2-bridged species with CO yields the complex [Rh2(CO)2(μ-CO)(μ-Cl)(DPM)2][Cl] which can then be readily converted in solution to the dicarbonyl species cis-[Rh2Cl2(CO)2(DPM)2]. The reaction of trans-[Rh2Cl2(CO)2(DPM)2] with SO2 has also been investigated and has been shown to occur by terminal SO2 attack, forcing the terminal carbonyl and chloro ligands on one Rh atom into the bridging positions. In solution this species then loses Cl- and rearranges to the complex [Rh2(CO)2(μ-Cl)(μ-SO2)(DPM) 2][Cl] which can yield [Rh2Cl2(μ-SO2)(DPM)2] by recoordination of Cl- and subsequent CO loss. The X-ray structural determination of [Rh2Cl2(μ-SO2)(DPM)2] shows this species to be a distorted "A-frame" complex with a symmetrically bridging SO2 ligand and terminal chloro ligands. The complex crystallizes in the space group C2h5-P21/c in a cell of dimensions a = 18.228 (1) A?, b = 13.526 (1) A?, c = 19.632 (2) A?, and β = 104.72 (1)° with Z = 4. On the basis of 5207 unique reflections, the structure was refined by full-matrix, least-squares techniques to agreement indices of R = 0.058 and Rw = 0.067. Some relevant metrical parameters are Rh-P(av) = 2.331 (9) A?, Rh-S(av) = 2.169 (2) A?, Rh-Cl(av) = 2.342 (2) A?, and Rh-S-Rh = 79.84 (7)°.
