286453-97-2Relevant academic research and scientific papers
Mechanistic control of product selectivity. Reactions between cis-/trans-[Os(VI)(tpy)(Cl)2(N)]+ and triphenylphosphine sulfide
Huynh, My Hang V.,White, Peter S.,Meyer, Thomas J.
, p. 2825 - 2830 (2000)
Reactions between the Os(VI)-nitrido complexes cis- and trans-[Os(VI)(tpy)(Cl)2(N)]+ (tpy is 2,2':6',2-terpyridine) and triphenylphosphine sulfide, SPPh3, give the corresponding Os(IV)-phosphoraniminato, [Os(IV)(tpy)(Cl)2-(NPPh3)]+, and Os(II)-thionitrosyl, [Os(II)(tpy)(Cl)2(NS)]+, complexes as products. The Os-N bond length and Os-N-P angle in cis-[Os(IV) (tpy)(Cl)2(NPPh3)](PF6) are 2.077(6) A and 138.4(4)°. The rate law for formation of cis- and trans-[Os(IV)(tpy)(Cl)2(NPPh3)]+ is first order in both [Os(VI)(tpy)(Cl)2(N)]+ and SPPh3 with k(trans)(25 °C, CH3CN) = 24.6 ± 0.6 M-1 s-1 and k(cis)(25 °C, CH3CN) = 0.84 ± 0.09 M-1 s-1. As found earlier for [Os(II)-(tpm)(Cl)2(NS)]+, both cis- and trans-[Os(II)(tpy)(Cl)2(NS)]+ react with PPh3 to give [Os(IV)(tpy)(Cl)2(NPPh3)]+ and SPPh3. For both complexes, the reaction is first order in each reagent with k(trans)(25 °C, CH3CN) = (6.79 ± 0.08) x 102 M-1 s-1 and k(cis)(25 °C, CH3CN) = (2.30 ± 0.07) x 102 M-1 s-1. The fact that both reactions occur rules out mechanisms involving S atom transfer. These results can be explained by invoking a common intermediate, [Os(IV)(tpy)(Cl)2(NSPPh3)]+, which undergoes further reaction with PPh3 to give [Os(IV)(tpy)(Cl)2(NPPh3)]+ and SPPh3 or with [Os(VI)(tpy)(Cl)2(N)]+ to give [Os(IV)(tpy)(Cl)2(NPPh3)]+ and [Os(II)(tpy)(Cl)2(NS)]+.
