Synthesis and Redox Studies on Ruthenium and Osmium Complexes with Primary and Secondary Phosphines. Single-crystal Structures of trans- and trans-*CH2Cl2

Article abstract of DOI:10.1039/DT9940003377

Reaction of RuCl3*3H2O or 2 with 5-7 molar equivalents of PR2H(R = Ph or C6H11) or PPhH2 in degassed refluxing EtOH solution (or EtOH-water for Os) gave and in high yield as yellow solids.Ultraviolet-visible and 31P NMR spectroscopic studies confirm that these species exist as trans isomers in solution and the integrity of the PH functions.Prolonged standing of trans- in CH2Cl2 solution led to partial isomerisation to the cis isomer as confirmed by 31P NMR spectroscopy.The crystal structure of trans- has been determined.It confirms a trans arrangement of the Cl(1-) ligands with the Ru(II) occupying a crystallographic inversion centre with four precisely coplanar equatorial PPhH2 ligands, Ru-Cl 2.422(3), Ru-P(1) 2.319(3) and Ru-P(2) 2.318(3) Angstroem.The lower steric demands of the PPhH2 ligands compared to PPh2H are reflected in the more regular octahedral arrangement seen in trans- compared to trans-*0.5CHCl3.The crystal-structure determination of trans-*CH2Cl2 showed two independent half molecules in the asymmetric unit with each Os(II) occupying an inversion centre and co-ordinated to a trans arrangement of two Cl(1-) and four PPh2H ligands, Os(1)-Cl 2.448(2), Os(2)-Cl 2.443(2), Os(1)-P 2.357(2), 2.349(2), Os(2)-P 2.355(2), 2,333(2) Angstroem.With the exception of (irreversible), cyclic voltammetric studies on the complexes trans- and trans- show a reversible oxidation in each case, which is assigned to a M(II)-M(III) redox couple.

Full text of DOI:10.1039/DT9940003377

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