New Cationic and Neutral Ru(II)- and Os(II)-dmso carbonyl Compounds

The
preparation and structural characterization of three cationic
Ru­(II)-dmso carbonyls and of four neutral mono- and dicarbonyl Os­(II)-dmso
derivatives is reported. The two monocarbonyl species fac-[Ru­(CO)­(dmso-O)3(dmso-S)2]­[PF6]2 (11) and cis,cis,cis-[RuCl­(CO)­(dmso-O)2(dmso-S)2]­[PF6] (12) were obtained from the neutral
monocarbonyl precursor cis,trans,cis-[RuCl2(CO)­(dmso-O)­(dmso-S)2] (3) upon stepwise replacement of the chlorides with
dmso, that binds in each case through the oxygen atom. The dicarbonyl
cationic complex cis,cis,trans-[Ru­(CO)2(dmso-O)2(dmso-S)­Cl]­[PF6] (13) was instead obtained upon treatment of
the neutral tricarbonyl precursor fac-[RuCl2(CO)3(dmso-O)] (8) with AgPF6 in
the presence of DMSO: replacement of a Cl– with
a dmso-O implied also the substitution of one CO ligand by another
dmso (that binds through S trans to Cl). The Os­(II)
carbonyls trans,trans,trans-[OsCl2(CO)­(dmso-O)­(dmso-S)2] (17), trans,cis,cis-[OsCl2(CO)2(dmso-O)2] (18), cis,mer-[OsCl2(CO)­(dmso-S)3] (19), and cis,trans,cis-[OsCl2(CO)­(dmso-O)­(dmso-S)2] (20) were obtained by treatment of the Os­(II)-dmso
precursors trans-[OsCl2(dmso-S)4] (14) and cis,fac-[OsCl2(dmso-O)­(dmso-S)3] (15) with CO. Each one of them is structurally similar to an
already known Ru­(II) analog, even thoughin agreement with
the expected greater inertness of Os­(II)more forcing reaction
conditions were required for their preparation. Interestingly, compound 20 could not be isolated in pure form, but only as a 1:1 cocrystallized
mixture with its precursor 15. The dmso ligand is always
bound through the oxygen atom when trans to CO. We are confident that
the new Ru­(II)- and Os­(II)-dmso carbonyl species described here represent
a contribution to expand the pool of complexes bearing some easily
replaceable dmso ligands to be used as well-behaved precursors in
inorganic synthesis.