Osmium iv

During an extensive study of the polarographic behaviour of tris(p-diketonato)ruthenium(iii) complexes in DMF solution, it was observed that [Os(acac)3] was more difficult to reduce (by 0.52 V) than its Ru analogue. Also studied was the sulphur derivative [Os(sacsac)3]. An e.s.r. investigation of the hyperfine splitting in the complex Na3[OsCl6] has confirmed the value of the nuclear spin / = f for the odd isotope Os, which was known earlier only from n.m.r. measurements. 

OsmiumClV).—Brown salts of formula Cs3[Os3(N)2Xii(NH3)3], 2H2O (X = Q or Br) have been precipitated from the reaction between OsO and concentrated aqueous ammonia. I.r. spectral data and their diamagnetism indicate the Os -Os -Os structure (24), which is similar to that of ruthenium red, but contains bridging nitrido ligands. The green polymer K [Os(N)Br4] , 

Paper chromatographic methods have been described for the separation of 60 different metal complexes and ions, including [OsCl ] , for which Rp values are given with various eluents. The Gibbs energy of formation (AG ) of brown OSO2 has been determined by an e.m.f. method, and published thermodynamic data for this oxide and OSO4 have been reviewed.  

Further results have appeared from Kiel on kinetics of substitution processes in the hexahalogeno-osmate(IV) systems containing various com- 

The hexafluoroosmate(IV) anion, [OsFe] , is extremely inert to aquation. However, aquation of this complex can be catalyzed by zir-conium(IV) rate constants for a range of conditions have been reported. Interestingly and surprisingly, rate constants for zirconium(IV)-catalyzed aquation of [OsFe] , [ReFe] , [PtFe] , and [PFe] are the same under identical conditions. The rate-determining step must therefore involve only the zirconium. Comparison of rate constants for these catalyzed aquations with rate constants obtained in a study of depolymerization of polynuclear zirconium(IV) species in aqueous solution shows that the catalyzed aquation 

Substitution Reactions—Nos. 6 and Above Other Inert Centers 

The principal bands are ligand-to-metal CT in nature and were assigned using a j-j model. 

Reaction of (NH4)20sCl6 with EPhj (E = P or As) allows isolation of trans-OsCl4(EPh3)2. A paramagnetic, octahedral osmium(iv) complex of 3,3 -diamino-4,4 -dihydroxydiphenyl-sulphone has been prepared.The thermal decomposition of Os(phthalocyanine)S04 has been studied. 

Rate and equilibrium data associated with reaction (9) (X= Cl, Br, or I) are summarized in Table 20. Values of / aq decrease with changes in X in the order I  

Br Cl although the rate differences are not very large at 293.2 K. Halide exchange reactions were shown to proceed via prior aquation.  

Kulprathipanja, D. J. Hnatowich, and S. Treves, J. Inorg. Nuclear Ghent., 1977, 39, 933. P. Hambright, Inorg. Nuclear Ghent. Letters, 1977, 13, 403. 

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Interaction between osmium(IV) and osmium(VI) and derivatives of dimerkaptotiopiron (DT) has been studied by amperemetric, potentiometric and spectral photometric methods in different mediums. It has been found out that in reactions of methyldimerkaptotiopiron (R) with Os(IV) and Os(VI) complex formation prevails. It has a step-like nature, being revealed by such change of ratio of Os R in the course of titration as Os(VI) R - from 1 1 to 1 4 in acid medium and from 2 1 to 1 4 in weak alkaline medium Os(IV) R - from 1 1 to 1 5 in medium of H SO and from 1 1 to 1 6 - in HCl medium. 

Consequent potentiometric titration of osmium(IV) and laithenium (IV) in their mixtures has been canied out in broad range of concentrations from 1 mkg to 200 mkg in samples of 20 ml. It has been shown the possibility of amperemetric determination of osmium(VI) in binary and triple systems with silver(I), platinum(IV), palladium(II), gold(III), founded on formation of corresponding compounds with dimerkaptotiopiron, having a different solubility. The deteriuination of Os(VI) is possible under tenfold - hundredfold excess of above mentioned metals. 

The extraction of osmium(VI) and osmium(IV) compounds with dimerkaptotiopiron by polar solvents has been resear ched. 50 -100 - multiple concentrating has been carried out in acid solutions regardless from chemical form of Os(VI) and Os(IV) with the following determination of each of them from one sample by amperemetric titration of reextracts by means of DT. A methodic of atom absor ption determination of osmium has been suggested. 

Pseudohalides of Se in which the role of halogen is played by cyanide, thiocyanate or selenocyanate are known and, in the case of Se are much more stable with respect to disproportionation than are the halides themselves. Examples are Se(CN)2, Se2(CN)2, Se(SeCN)2, Se(SCN)2, Se2(SCN)2. The selenocyanate ion SeCN is ambidentate like the thiocyanate ion, etc., p. 325), being capable of ligating to metal centres via either N or Se, as in the osmium(IV) complexes [OsCl5(NCSe)], [OsCl5(SeCN)], and trans-[OsCU(NCSe)(SeCN)]2-.920) Tellurium and polonium pseudohalogen analogues include Te(CN)2 and Po(CN)4 but have been much... 

Ruthenium(IV) produces few other complexes of interest but osmium(IV) yields several sulfito complexes (e.g. [0s(S03)6] and substituted derivatives) as well as a number of complexes, such as [Os(bipy)Cl4] and [Os(diars)2X2] (X = Cl, Br, I), with mixed halide and Group 15 donor atoms. The iron analogues of the latter complexes (with X = Cl, Br), are obtained by oxidation of... 

The osmium(IV) complexes are only obtained by this route with fairly unreactive phosphines and arsines (e.g. PBu2Ph) but they are conveniently made by oxidation of mer-OsX3(QR3)3 (Q = P, As) with the halogen in CHC13, or CCI4 and refluxing. 

By comparison, oxidation of wer-Os(PR3)3Cl3 systems affords paramagnetic osmium(IV) species mer-Os Rs Cl (the corresponding fac-species can only be oxidized electrochemically) [152]. Other osmium(IV)... 

Osmium forms a 6-coordinate acetylacetonate, Os(acac)3, isomorphous with the ruthenium analogue unlike ruthenium, however, the osmium(IV) complexes Os(acac)2X2 (X = Cl, Br, I) can be made (cis- and frans-isomers exist) from OsXg- and Hacac, as can Os(acac)X [176]. 

The osmium(IV) complexes can be made by oxidation of the osmium(III) systems [152] ... 

Mit Nickel(II)-, Osmium(IV)-, Iridium(III)- und Platin(II)-chlorid werden ahnliche Ergebnisse erzielt. In Gegenwart von Raney-Nickel geniigt ein 100°/oiger Natriumbora-nat-t)berschu63. 

Schemes 6-17 Reaction of hydrido(carboxylato)osmium(IV) complexes with alkynes...

In spite of the rich chemistry developed starting from the OsHCl(CO)(P Pr3)2 complex, the presence of a carbonyl group in its coordination sphere is probably a limitation for some subsequent developments. In this context it seems important to mention the encouraging reactivity of the related osmium(IV) complex, OsH2Cl2(P Pr3)2, that in methanol afford OsHCl(CO)(P Pr3)2. We believe that both interrelated osmium complexes present not only a rich chemistry but also a promising future as starting materials in organometallic chemistry. 

Manganese trichloride oxide, 4141 Mercury(I) oxide , 4613 Mercury(II) oxide, 4605 Molybdenum(IV) oxide, 4716 Molybdenum(VI) oxide, 4717 Nickel(II) oxide, 4821 Nickel(III) oxide, 4823 Nickel(IV) oxide, 4822 Niobium(V) oxide, 4818 Osmium(IV) oxide, 4833 Osmium(VIII) oxide, 4858 Palladium(II) oxide, 4825 Palladium(III) oxide, 4848 Palladium(IV) oxide, 4835... 

Osmium(iv).—Group VII Donors. Simple syntheses of hexafluoro-complexes of some noble metals have been reported, e.g. 

Although a number of stable osmium(IV) phosphoraniminato complexes are known, the corresponding osmium(V) complexes are unstable. The net reaction for one-electron oxidation of [Os (NPPh3)(tpy)(Cl)2] to Os " is shown in Equation (54). The reaction presumably occurs by initial disproportionation of Os to Os " and Os " followed by PPh3 transfer. Similarly,... 

Osmium(V) sulfilimido complexes can be generated by electrochemical or chemical oxidation of the corresponding osmium(IV) complexes (see Section 5.6.6.4.5). 

These bis(amido)ruthenium(IV) and bis(amido)osmium(IV) porphyrin complexes show well-resolved H NMR spectra with the signals of the porphyrinato ligands appearing at normal fields, indicating that they are all diamagnetic. 

An osmium(IV) imido species, [Os(NH)(tpy)(bpy)] ", has been proposed to be the active intermediate in the formation of nitrosamines from the oxidation of coordinated ammonia in... 

Osmium(IV) cyanoimido complexes can be prepared by the interaction of osmium(VI) nitrido complexes with CN (Equations (62b) and (62e) see also Scheme 6 and Seetion 5.6.4.2.2(ii)). 

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