Diarsine ligand

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

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. 

All tetrahalo complexes [M(bidentate)2X4]JC are observed to have stereochemistry A as predicted. The diarsine ligands in [M C6H4(AsMe2)2 2X4]I+, where M is TiIV, NbIV, Nbv, Tav, Mov... 

When the diarsine ligand (17) is allowed to react with rhodium trichloride in refluxing DMF, the bridged complex [RhCl(17)]2 is formed (equation 31).107... 

The coordination chemistry of diphosphine and diarsine ligands has been intensively investigated in recent years.i Very much less work has been carried out on the corresponding mixed ligands, the intermediate arsine-phosphine bidentates, owing to a considerable extent to the lack, until recently, of suitable synthetic routes to such ligands. Two routes are now available the nucleophilic substitution of organohalogen compounds, two examples of which... 

Diarsine ligands. The double bond in AS2R2 stabilized via a n bond by... 

On the contrary [Rh6(CO)i5X] PC = I, CN, SCN) is not fluxional since all spectra remain identical between — 80 °C and + 30 °C [52]. This holds also for [Rh6(CO)iiC L2] , where L2 is a diphosphine or a diarsine ligand [52]. Thus, the structures of these clusters in solution are the same as in the solid state. In the species [Rh fCOjisX]", where X = I, CN, SCN, the resonances of the rhodium atoms bound to X are always at the highest frequency (see Table 4) [52]. In contrast, when X = H the reverse holds [49]. This again provides evidence that the assignment of Rh resonances cannot be predicted on the basis of simple rules. 

The reverse reaction, deprotonation of a vanadium hydride complex to produce an anion, is known. Thus, V(CO)4L2H (L2 = a chelating diphosphine" or diarsine ligand) can be converted to [V(CO)4L2] with OH or NEts. (t -l,3,5-Me3C6H3)V(CO)3H can also be deprotonated with hydroxide ion . 

We can actually see the process of electron pair shift with a resultant change in structure in the complex ion [Co(diars)2NO)J+ (where diars is a bidentale diarsine ligand) (Fig. 15.17). The 18-electron rule predicts that the nitrosyl group will be linear (a three-electron donor), as indeed it is. Reaction of this complex with the thiocyanate ion (a two-electron donor) would violate the 18-electron rule unless a pair is shifted from a molecular orbital of largely metal character to an orbital on nitrogen. This is in fact what happens and stereochemical control of valence" results.47 As NO goes from being a three-electron to a one-electron donor, a coordination site capable of... 

Gold(m) complexes have been obtained by using a chelating diarsine ligand from the reaction with sodium tetrachloroaurate(m) in presence of sodium iodide. The iodide [Au(diars)2I2]I and other cations, [Au(diars)2l]2+ and [Au(diars)2]3 +, can be obtained. It is held that these are species with six, five and four coordination for Au111 with octahedral,33 trigonal bipyramidal and planar structures, respectively. Chelating phosphine complexes also exist. 

Looking at the results obtained with BINAP, with the new diarsine ligand mentioned in Sect. D.i.a and with bisoxazoline 132, it seems evident that various donor atoms (N, P, As) can be contained in ligands which provide the best solution to a given AHR problem. Accordingly, recently 2-diphenylarsino-2 -diphenylphosphino-l,r-binaphthyl... 

The complex [Fe,(CO),(AsM (AsMe2C C-CF -CF )] (14) is considered novel in that the diarsine ligand used in the preparation has undergone cleavage of an AsM group. In the resulting molecular structure, the... 

The complex [Ruj(CO)io(Me2AsC C AsMejs-CF -CF2)] (45) contains a triangular RUg fragment and a bridging diarsine ligand. It is regarded as a derivative of the [Rug(CO)i2] molecule, in which two equatorial carbonyl... 

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