Regioselective and stereoselective PPh 3 substitution in the imido-capped cluster Ru 3(CO) 10(μ 3-NPh). Electrochemical properties and X-ray diffraction structures of Ru 3(CO) 9(PPh 3)(μ 3-NPh) and Ru 3(CO) 8(PPh 3) 2(μ 3-NPh)· [formula omitted]CH 2Cl 2

Abstract

The imido-capped cluster Ru 3(CO) 10(μ 3-NPh) ( 1) reacts with PPh 3 under thermal and Me 3NO activation to give the corresponding phosphine-substituted clusters Ru 3(CO) 9(PPh 3)(μ 3-NPh) ( 2) and Ru 3(CO) 8(PPh 3) 2(μ 3-NPh) ( 3). Both d2 and 3 have been isolated and fully characterized in solution by IR and 31P NMR spectroscopy, and the solid-state structure of each new cluster compound has been established by X-ray diffraction analysis. 2 crystallizes in the monoclinic space group P2 1/ n: a=13.091(2), b=11.405(2), c=22.687(4)Å 3, β=99.80(1)°, V=3338(1) Å 3, Z=4, D calc=1.808 g cm −3; R=0.0399, R w =0.0511 for 3515 observed reflections. 3, as the CH 2Cl 2 solvate, crystallizes in the triclinic space group P 1: a=9.5678(8), b=14.425(1), c=17.986(1) A ̊ α=81.692(5), β=88.078(6), γ=77.716(6)°, V=2400.1(3) A ̊ 3, Z=2, D calc =1.640 g cm −3; R=0.0439, R w =0.0479 for 3570 observed reflections. The X-ray data establish the site of the first PPh 3 group at an axial position in the cluster 2 while cluster 3 derives from the formal replacement of an equatorial CO group on an adjacent ruthenium center in 2 by the second PPh 3 group. These results confirm the highly stereo- and regioselective ligand substitution reactivity attendant in this particular imido-capped cluster. The redox properties of 1–3 have also been explored by cyclic; voltammetry at a platinum electrode in THF solvent.