Diplatinum 194 compound

Pt-Pt bonds to be more prevalent than Ni-Ni or Pd-Pd bonds. Actually, a search in the Cambridge Structural Database (CSD version 03.2014) for Pt-Pt bonds gives 1173 hits, while searches for Pd-Pd and Ni-Ni bonds gives 857 and 732 hits, respectively. 

Among all possible oxidation states, diplatinum(III) (Ptj ) compounds represents the vast majority and the quantity of compounds is second only to dirhodium(II) compounds among till metal-metal bonded moieties. In a comprehensive textbook chapter in 2005, the structure and chemistry of Pt-Pt bonded compounds were nicely reviewed by Murillo, which the reader is recommended to consult [2]. Therefore, an encyclopedic coverage of the literature is not the aim of the following section, and a representative selection of highlights made since 2005 will be introduced. 

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Only one reaction is known in which a gold compound reacts with HFA. (Triphenylphosphane)methylgold(I) forms a four-membered ring 190, which is assigned a structure related to the diplatinum compound 186 (196). 

Addition of further electrons, which enter the n and finally the a orbitals, causes decreases in the formal bond orders, by half-integer units from 2.5 eventually to 0. In the vast number of dirhodium compounds there is a Rh + core which has a single bond based on the a2J7452 5 2J7 4 configuration. Recently a set of diplatinum compounds shown in Table 16-1 has provided examples of the progression from bond order 1 to 0. 

Scheme 10.86 Synthesis of a mixed-valent Pt(IV)-Pt(ll) diplatinum compound 211.

Table 10.15 Pt-Pt bond lengths in mixed-valent diplatinum compounds.

As far as the arrangement is concerned, the cis complexes of type Pt(pym)2M are very common with a h-h bases arrangement (I, Fig. 4), whereas a h-t pattern is found in diplatinum complexes (V, Fig. 4). These compounds are prepared through a condensation reaction between mononuclear complexes, according to... 

Fig. 2. Schematic structures of compounds related to platinum blues . Diplatinum(II) species with HH (A-l) and HT (A-2) oriented amidate ligands, tetraplatinum(II) species (A-3), tetranuclear [Pt2 25]4 blues without (B-l) and with axial ligand (B-2), tetranuclear [Pt2 5]4 tans (C-l, C-2), and various types of diplatinum(III) species with HH (D-l, D-3) and HT (D-2) orientation of the bridging ligands. The amidate ligands are expressed with their N- and O-coordinating atoms only.

Recently compounds containing cyclic polyolefins coordinated to platinum or palladium have received considerable attention as a result of the unique bonding found in these compounds and their possible use as intermediates in a variety of reactions. Several methods have been reported for the synthesis of these compounds, and among these procedures the displacement of ethylene1 from di-Ju-chloro-dichlorobis(ethylene)diplatinum(II) and benzonitrile2 from dichlorobis(benzonitrile)palladium(II) are the most generally applied procedures. Both of these methods involve the preparation of intermediates before the isolation of the product, and in addition these intermediates tend to decompose upon storage. 

In 1982, novel diplatinum(II) diphosphite complexes were reported162. These compounds were readily generated by oxidative addition to the binuclear platinum(II) tet-rakis(diphosphite) complex, [Pt2(pop)4]4 (pop = P205H2 ), with halogens or methyl... 

Structural Data for Quadruply Bridged Diplatinum, Dipalladium, and Dinickel Compounds"... 

Preparation of carbon-bonded CH2COO complexes gives the impression that the platinum ion favors carbon-bonded structures as is known in the case of various mononuclear platinum complexes (26-29), and the tetraacetate complexes do not exist as stable compounds. The tetra(acetato)diplatinum complex, [Pt2(CH3C00)4(H20)2] (Fig. 8), was eventually prepared, however, by refluxing a solution of K2[Pt (NOalJ in CH3COOH-I M HCIO4 (2 1) (30, 31). 

H, C, P, and Pt NMR spectra are available in the literature for various lantern-type diplatinum complexes. H, C, and P NMR spectra have been used mainly for structural assignments and are not useful for comparison among various lantern-type compounds with different bridging ligands. 

Platinum(II) salts behave similarly, although the range of cycloplatinated compounds is less extensive. Thus, chloride-bridged diplatinum complexes may be prepared with metallated N ligands such as azobenzene, 2-phenylpyridine, or 8-methylquinol-line . Tertiary phosphine and arsine complexes also may undergo metallation ... 

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