59683-36-2Relevant academic research and scientific papers
Kinetics of aquation of hexachloroosmate(IV) and chloride anation of aquopentachloroosmate(IV) anions
Miano, Ralph R.,Garner, Clifford S.
, p. 337 - 342 (1965)
The kinetics of the reactions OsCl6-2 + H2O ?k-1k1 Os(OH2)Cl5- + Cl- have been investigated in HCl medium at 80°; the forward reaction has also been studied at 70-89° in HNO3 medium, in which the aquation product and secondary products are rapidly oxidized to OsO4 and Cl-. In 0.00001-0.1 F HNO3 (μ = 0.5-1.32, NaNO3), and by deduction in HCl of the same acidity, k1 = 3.5 × 10-6 sec.-1 at 79.53° in the dark; Ea = 33.1 ± 0.6 kcal., log pZ = 15.1 ± 0.4 (sec.-1), ΔH°*298 = 32.5 ± 0.6kcal., ΔS°*298 = 841 ± 2 cal. deg.-1, k1 (calcd.) = (6 ± 1) × 10-10sec.-1 at25°. In 0.5-1.32 FHNO3 (μ = 1.32, NaNO3) at 80° the rate of disappearance of OsCl6-2 is up to 30% greater than for 0.00001-0.1 F H+, apparently due to a contribution from oxidation of OsCl6-2 to OsCl6-2 and Cl-. In 0.01-1.32 F HCl (μ = 1.32, NaCl) at 80°, the previously uncharacterized Os(OH2)Cl5- is the only product observed at short reaction times; the rate of loss of OsCl6-2 in 1.32 F H+ (where k = 4.17 × 10-6 sec.-1, close to k1 in 0.00001-0.1 F HNO3, μ = 1.32, at 80°) is ca. 14 times that in 0.01 F H+. Rate runs made in 0.016 F HCl with added low concentrations of different oxidants give k values approaching or nearly equal to k1 for 0.00001-0.1 F HNO3; the abnormally high rates of OsCl6-2 loss in HCl at low acidities may arise from reduction by Cl- of very small amounts of OsCl6-2 to one or more hydrolytically more labile complexes. Chloride anation of Os(OH2)Cl5- was studied at 79.53° in 2.49-3.80 F Cl-, 2.46-3.80 F H+ (μ = (Cl-), KCl). An exact first-order dependence on (Cl-) was not observed, 105k-1 varying from 1.01 to 1.97 M-1 sec.-1; in 3.3-3.8 F HCl k-1 ≈ 2 × 10-5 M-1 sec.-1. The visible and near-ultraviolet absorption spectrum of Os(OH2)Cl5- is reported. Compounds described in the literature as pentachlorohydroxy osmate-(IV) salts, M2[Os(OH)Cl5], are very probably binuclear complexes, M4[Cl5OsOOsCl5]·H2O.
Synthesis and reaction of the novel complex [AsPh4][OsCl5(H2O)]. X-ray structure analysis of [AsPh4][OsCl5(H2O)]·2EtOH and [AsPh4][OsCl5(EtOH)]·EtOH
Maiboroda,Rheinwald,Lang
, p. 5725 - 5730 (2008/10/08)
The synthesis and characterization of the anionic, mononuclear and homobinuclear osmium complexes [AsPh4]-[OsCl5L]·xEtOH [L = H2O, x = 2 (9); L = EtOH, x = 1 (10a); L = py, x = 0 (10b)] and [AsPh4]2[Cl5Os-(pyz)OsCl5] (12) (pyz = pyrazine) are described. Upon reduction in a chloride-containing medium, OsO4 (1) affords the osmium(IV) species [OsCl5(H2O)]- (2), which could be isolated by extraction with n-tributyl phosphate (TBP): Complex 9 is the first fully characterized chloroaquo complex of Os(IV). This complex is an effective starting material for the preparation of novel species, such as 10a, 10b, and 12. The X-ray structures of 9 and 10a were determined. Both compounds crystallize in the monoclinic space group P21/n. 9: C28H34AsCl5O3Os, a = 10.910(4) A, b = 17.127(5) A, c = 17.555(7) A, β = 103.77(2)°, V = 3186(2) A3, and Z = 4. 10a: C28H32-AsCl5O2Os, a = 10.7762(2) A, b = 17.3939(1) A, c = 17.1477(3) A, β = 103.645(1)°, V = 3123.45(8) A, and Z = 4. Complexes 9 and 10a crystallize with two and one molecule of EtOH and are bonded via hydrogen bridges to the H2O and EtOH ligand in 9 and 10a, respectively.
