Palladium complexes selenium

Selenium analogs of the mercury and palladium complexes are known, but no simple selenide complexes seem to have been reported. 

N. Bartlett and J. W. Quail, The Preparation of Palladium Difluoride and Complex Fluorides of Palladium in Selenium Tetrafluoride, J. Chem. Soc. (1961) 3728-3732. 

However, the H NMR spectrum of this compound, and that of a similar palladium complex, shows temperature dependence, which is considered to reflect site inversion about the selenium atom, rather than ring inversion (i.e. (20) (2l) and (22) (23) (Scheme 12) <76JCS(D)1227>. 

Little C—Se bond formation by palladium catalysis has been reported, although these reactions should be feasible considering the ability of palladium complexes to catalyze C—S, C—P, and C—As bond formation. However, nickel complexes have been used for carbon-selenium bond formation. In 1985, Cristau and co-workers used bis(bipyridyl)nickel(ll) bromide to form aryl selenides from aryl halides and sodium benzeneselenoate. ... 

Selenium occurs in the slimes as intermetallic compounds such as copper silver selenide [12040-91 -4], CuAgSe disilver selenide [1302-09-6], Ag2Se and Cu2 Se [20405-64-5], where x < 1. The primary purpose of slimes treatment is the recovery of the precious metals gold, silver, platinum, palladium, and rhodium. The recovery of selenium is a secondary concern. Because of the complexity and variabiUty of slimes composition throughout the world, a number of processes have been developed to recover both the precious metals and selenium. More recently, the emphasis has switched to the development of processes which result in early recovery of the higher value precious metals. Selenium and tellurium are released in the later stages. Processes in use at the primary copper refineries are described in detail elsewhere (25—44). 

Hi) Dehydrogenation. j3-Carboline derivatives may be obtained from tetrahydro-)3-carbohnes by zinc dust distillation or high temperatmre dehydrogenation with selenium or palladium black. Many of the complex indole alkaloids may be degraded, with bond cleavage, to yield simple )3-carbolines under these conditions and this approach has become a standard method in structural elucidations. Examples are numerous but outside the scope of this review. 

The selenium ligands, where w = 2, all form chelate complexes with the chlorides and bromides of palladium(II) and platinum(II) and with platinum(II) iodide. In the case ol m =3, the only chelate complexes isolated were those of the type PtX2L (X = Cl, Br I.)... 

This section of the coverage of palladium(II) coordination chemistry will concentrate on complexes of the more common, usually unidentate ligands containing sulfur, selenium or tellurium donor atoms coverage of the vast number of chelate complexes of bi- or multi-dentate ligands will be limited but the reader will find references to most classes of palladium(II) chelate complexes and these will provide an entry into the literature. 

The number and variety of coordination complexes of palladium(II) with sulfur-containing bidentate or multidentate ligands is legion, and it is possible here only to summarize the different kinds of complexes formed and to guide the reader into the literature. Table 2 contains a selection of typical palladium(II) complexes of bi- or multi-dentate sulfur or selenium donor ligands, and comments on pertinent aspects of particular complexes. Chelate... 

Table 2 Some Typical Palladium(II) Complexes of Bi- or Multi-dentate Sulfur or Selenium Donor Ligands...

---