Diarsines

Other Arsenic Hydrides. Diarsine [15942-63-9] AS2H4, occurs as a by-product in the preparation of arsine by treatment of a magnesium aluminum arsenide alloy with dilute sulfuric acid and also may be prepared by passing arsine at low pressure through an ozonizer-type discharge tube (19). Diarsine is fairly stable as a gas but quite unstable (above — 100°C) in condensed phases. The for diarsine is +117 4 kJ/mol (28 1 kcal/mol) and... 

Finally, secondary arsines can be obtained by the reductive cleavage of diarsines with mercury and hydrogen iodide (49) or with hthium aluminum hydride... 

Diarsines and Diarsenes. Under certain conditions, the reduction of compounds with two organic groups attached to arsenic may give rise to tetraalkyl-or tetraaryldiarsines. Thus a number of diarsines have been obtained by the reduction of arsinic acids with phosphorous or hypophosphorous acid (100). Diarsines can also be prepared by the treatment of a metal dialkyl- or diarylarsenide with iodine (101) or a 1,2-dihaloethane (102). 

Diarsines are extremely reactive compounds. Tetramethyldiarsine (cacodyl) [471-35-2] and tetraethyldiarsine [612-08-8] CgH2QAs2, are... 

Unlike many distibines and dibismuthines, diarsines do not appear to exhibit thermochromic effects (105). 

Comparison with data (mainly obtained from EXAFS measurements) on osmium diarsine complexes (Table 1.14) shows that as the oxidation state increases, osmium—halogen bonds shorten whereas Os-P and Os—As bonds lengthen. Bond shortening is predicted for bonds with ionic character,... 

Complexes of diphosphines and diarsines can be prepared by various routes the following are typical... 

Figure 4.40 4-Coordination in AuMe3(diars) made possible by a monodentate diarsine ligand.

Detailed procedures for the synthesis of various often used [Ni°L4] complexes (L = phosphines, arsines, stibines, alkyl isocyanides) and [Ni°L 2] complexes (L = bipyridine, phenantroline, diphosphines, diarsines) have been compiled.2413... 

The diarsine and arsine/phosphine analogues of dppm have been used to prepare bridged diplatinum(I) complexes, in both cases with terminal chloro ligands.116,117 Both complexes react with carbon monoxide to produce carbonyl-bridged species. The mixed thio/phosphine ligand Ph2PCH2SMe (PS) also forms a diplatinum(I) complex by conproportionation of its dichloroplat-inum(II) complex with [Pt(dba)2].118 This dimer reacts with carbon monoxide to produce an unsupported dimer [PtCl(PS)(CO)]2 with the thioether arm of the Ph2PCH2SMe unbound. 

Independently, triangulo-Hg3 compounds with stabilizing chelating diphosphine and diarsine ligands have been prepared, 82-387 crystal-structure analyses have been solved (the Hg—Hg bonds, 280 pm, are longer than before), and careful multinuclear NMR spectra measured and analysed. 

An alternative preparative route to R2QER acid esters (Q = P, As, Sb, Bi E = S, Se, Te) of interest due to its generally applicability to all the heavier group 15 and 16 elements, is the dismutation reaction between diorganodichalco-genides and tetraorgano-diphosphines, -diarsines, -distibines or -dibismuthines (Equation 17).2... 

In sharp contrast to the intensely studied reactions of dipenteles with transition metal compounds, reactions with group 13 metal compounds are almost unknown. Only two diphosphine-borane bisadducts of Type C ([H3B]2[Me4P2], [H2(Br)B]2[Me4P2]) have been synthesized and structurally characterized65 but no diarsine, distibine or dibismuthine adducts. We, therefore, became interested in the synthesis of such compounds, focusing... 

In contrast, the sodium complex [Na(AsPh2)(dioxane)]x is polymeric in the solid state [Na-As = 2.962(4), 2.937(4) A] (25). This complex was synthesized by the rather unusual method of sodium reduction of a diarsine ... 

The work on complexes of metals of other groups with olefinic tertiary phosphines and arsines has until recently been neglected, but it has now become dear that the chelating properties of these ligands are almost as widespread as those of the more well known bis(phosphine) and bis(arsine) ligands, such as diphos and diarsine. 

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