Arsines polydentate

Complexes are similarly formed by polydentate phosphine and arsine ligands synthetic routes involve oxidation of the platinum(II) complex, either with the halogen or with nitric acid ... 

Zirconium and hafnium tetrahalides form six-, seven- and eight-coordinate adducts with polydentate phosphine and arsine ligands. The 1 1 adducts [MXt(dppe)] and [MX dpae)] (M = Zr, X = C1 or Br M = Hf, X = C1 dppe = Ph2PCH2CH2PPh2, dpae = Ph2AsCH2CH2AsPh2) have been prepared in benzene media. IR spectra of the [MCLt(dppe)] complexes exhibit four v(M—Cl) modes in the 353-278 cm-1 region, consistent with a six-coordinate octahedral structure.45... 

Polydentate olefin substitution has been studied mainly in Group VIB metal complexes. The compound Mo(CO)4(7r-CgHi2) undergoes substitution (87, 88) with l,2-bis(diphenylphosphino)ethane, 2,2 -dipyridyl, 1,10-phenanthroline, and triphenylphosphine, -arsine, and -stibine, producing Mo(CO)4L2 or Mo(CO)4D, where L and D are, respectively, the mono- and bidentate ligands. The reaction rate is described by the equation... 

As for phosphine macrocycles, arsine macrocycles involve very difficult synthetic chemistry. The reasons for the difficulties are essentially threefold (i) the volatility and well-known toxicity of the arsenic-containing precursors (ii) the instability of coordinated As—II functions, which renders template cyclizations of limited use for arsenic macrocycles (iii) the high energy barrier to inversion at arsenic (167.4kJmol 1),41 which means that high-dilution cyclizations of polydentate arsine macrocycles leads to mixtures of stereoisomers which are not at all trivial to separate. On the other hand, the macrocyclic (tertiary) arsines are less susceptible to oxidation than their phosphine analogs. 

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