Osmium(II) and Osmium(IV) Complexes with Phosphane–Ethers, –Esters, and –Amines as Mono‐ and Bidentate Ligands

Abstract

AbstractThe six‐coordinate dihydridoosmium(IV) complex [OsH2Cl2(PiPr3)2] (1) reacted with the hemilabile chelating phosphanes iPr2PCH2CH2OMe and iPr2PCH2CO2R (R = Me, Et) at room temperature to give the substitution products [OsH2Cl2(iPr2PCH2CH2OMe)2] (2) and [OsH2Cl2{κ2(P,O)‐iPr2PCH2C(=O)OR}{κ(P)‐iPr2PCH2CO2R}] (3, 4) in good to excellent yields. Treatment of 1 with iPr2PCH2CH2NMe2 led to the displacement of only one PiPr3 ligand and gave [OsH2Cl2(PiPr3)(iPr2PCH2CH2NMe2)] (5). The reaction of 1 with iPr2PCH2CH2OMe and iPr2PCH2CO2R (R = Me, Et) at elevated temperature afforded the osmium(II) complexes [OsCl2{κ2(P,O)‐iPr2PCH2CH2OMe}2] (6) and [OsCl2{κ2(P,O)‐iPr2PCH2C(=O)OR}2] (7, 8), which were also obtained on heating the osmium(IV) precursor 3 or the labile 1:1 adducts of 3 and 4 with ethene in benzene under reflux. The dihydrido compounds 2 and 3 reacted with CO at room temperature to give initially the octahedral all‐cis‐configured complexes [OsCl2(CO)2{κ(P)‐iPr2PCH2CH2OMe}2] (11a) and [OsCl2(CO)2{κ(P)‐iPr2PCH2CO2Me}2] (12a), which rearrange to the more stable cis,cis,trans isomers 11b and 12b in benzene under reflux. The all‐trans isomer 11c and themonocarbonyl complexes trans,trans‐[OsCl2(CO){κ2(P,O)‐iPr2PCH2C(=O)OR}{κ(P)‐iPr2PCH2CO2R}] (13, 14) were prepared by passing CO through a solution of 6–8 in benzene or toluene/dichloromethane at room temperature. While the osmium(IV) compounds 3, 4 as well as the osmium(II) complexes 7, 8 reacted with CNtBu to give the neutral complexes cis,cis,trans‐[OsCl2(CNtBu)2{κ(P)‐iPr2PCH2CO2R}2] (15, 16), treatment of 5 with CNtBu afforded the ionic product [OsHCl(CNtBu)2(PiPr3)(iPr2PCH2CH2NHMe2)]Cl (17). The reaction of 7 with Ph2CN2 did not lead to the formation of a (carbene)osmium(II) compound but gave the dinitrogen complex trans,trans‐[OsCl2(N2){κ2(P,O)‐iPr2PCH2C(=O)OMe}(κ(P)‐iPr2PCH2CO2Me)] (18) instead. The structurally related vinylidene complexes trans,trans‐[OsCl2(=C=CHPh){κ2(P,O)‐iPr2PCH2CH2OMe}{κ(P)‐iPr2PCH2CH2OMe}] (19a) andtrans,trans‐[OsCl2(=C=CHPh){κ2(P,O)‐iPr2PCH2C(=O)OR}{κ(P)‐iPr2PCH2CO2R}] (20, 21) were prepared from 6–8 and PhC≡CH as starting materials. The cis,cis‐configuredcompound [OsCl2(=C=CHPh)(PiPr3){κ2(P,N)‐iPr2PCH2CH2NMe2}] (22) was obtained analogously from 5 and phenylacetylene. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)