Similarities and Contrasts between Silyl and Stannyl Derivatives of Ruthenium and Osmium

Abstract

Silyl and stannyl complexes of ruthenium and osmium bearing halogen substituents on the silicon and tin atoms undergo many interesting reactions. While there are formal similarities, there are also marked differences between these silyl and stannyl derivatives. This review first surveys the synthetic approaches we have developed to the silyl and stannyl complexes that involve oxidative addition of halogenated silanes coupled with reductive elimination for the preparation of the silyl complexes L n M(SiR n X 3-n ) (M ) Ru, Os) and reaction between L n MH and the vinylstannane R 3 SnCHdCH 2 to give first the triorganostannyl complexes L n M(SnR 3 ) (M ) Ru, Os), which are then functionalized by redistribution reactions to give L n M(SnR n X 3-n ) (M ) Ru, Os). Among the unusual compounds derived from these halogenated silyl and stannyl complexes are derivatives with the following novel ligands: Si(OH) 3 , Sn-(OH) 3 , silatranyl, stannatranyl, SnH 3 , and SnMe 2 SnPh 3 . A contrast between the osmasilanol L n Os(SiMe 2 -OH) and the osmastannol L n Os(SnMe 2 OH) is that the former deprotonates to a silanolate anion, [L n Os(SiMe 2 O)] -, while the latter, when treated with base, ortho-stannylates a triphenylphosphine ligand. Another contrast is provided by the ease with which osmium trimethylstannyl complexes undergo R-methyl migration reactions.

Selective Substitution of One of the Substituents on Germanium in Coordinatively Unsaturated Ruthenium Germyl Complexes

“…In the IR spectrum of 5 ν(CO) appears at 1931 cm –1 . This is considerably higher than the ν(CO) (1913 cm –1 ) observed for 1 but is entirely consistent with the replacement of a tolyl group on germanium with a more electronegative ethoxy substituent . The two p -tolyl methyl groups in 5 are observed in the 1 H NMR spectrum at 2.34 ppm, and the ethoxy group protons are observed as triplet and quartet signals at 0.57 and 3.05 ppm, respectively.…”

“…Subsequent addition of a dithiocarbamate sulfur to the electrophilic germylene center followed by proton-assisted cleavage of the p -tolyl group from the resulting anionic complex and coordination of the second dithiocarbamate sulfur to ruthenium would give the observed product. The feasibility of transient germylene formation during the synthesis of 4 is supported by reports in which the migration of hydride or organo groups from silyl, germyl, and stannyl ligands to the adjacent transition metal was either observed directly or was strongly implicated by the nature of the products formed. ,− ,,,− It is noteworthy that we have only observed p -tolyl group substitution in tri- p -tolylgermyl complexes that are either coordinatively unsaturated (see below) or can become coordinatively unsaturated through the dissociation of a labile ligand. An alternative possibility for the mechanism of formation of 4 could involve dissociation of PPh 3 from 2b followed by coordination of the sulfur of an incoming dithiocarbamate ligand to ruthenium and addition of the second sulfur to germanium with subsequent loss of a p -tolyl substituent from the anionic intermediate, perhaps aided by proton transfer from the solvent mixture.…”

“…The coordinatively unsaturated phenyl complexes MCl(Ph)(CO)(PPh 3 ) 2 (M = Ru, Os) , have proven to be remarkably useful synthons, from which coordinatively unsaturated silyl, − stannyl, − and boryl − complexes can be simply prepared. The complex RuCl(Ph)(CO)(PPh 3 ) 2 can also be used to form coordinatively unsaturated germyl complexes, and reaction with HGe( p -tolyl) 3 proceeds smoothly on heating under reflux in benzene to give the red RuCl(Ge[ p -tolyl] 3 )(CO)(PPh 3 ) 2 ( 1 ) in good yield (Scheme ).…”

Preparation and Reactivity of Stannyl Complexes of Ruthenium(II) Stabilized by an Indenyl Ligand

“…The chemistry of transition-metal stannyl complexes has long been under development, − both because there is general interest in compounds containing trihalogen (SnX 3 ), triorgano (SnR 3 ), and recently , trihydride (SnH 3 ) groups as ligands and because introduction of a stannyl group often changes the properties of complexes and may modify the activity of noble-metal catalysts …”

Carbon, silicon, germanium, tin and lead

“…11 Organotin chemistry has been a focus this year, with reviews on stannides and intermetallic tin compounds 12 advances in the chemistry of the organotin hydrides, 13 quantitative-structure activity relationships 14 the biological activity of cationic organotin(IV) complexes 15 and a very readable comparison of silyl and stannyl derivatives of ruthenium and osmium. 16 An entire issue of the Journal of Organometallic Chemistry devoted to organotin chemistry showcased a range of new developments. 17…”