Diplatinum complexes

Yasuda N, Uekusa H, Ohashi Y (2004) X-Ray analysis of excited-state structures of the diplatinum complex anions in five crystals with different cations. Bull Chem Soc Jpn 77 933-944... 

The excited diplatinum complex is now predisposed to react further. The incipient Pt—Pt bond is partially formed and addition of hydrogen is enhanced 202... 

The diplatinum complexes [Pt(jU-H)SiR3(PCy3)]2 catalyze the addition of silanes R3SiH (R = Me, Et, PhCH2) Ph, OEt, Cl) to pentene-1, hexene-1, styrene, allyl chloride and 2-methylpropene. The relative reactivity order in silane is given, and the catalyst substrate ratio is 10-4-10-6 1. The majority of the reactions are carried out at ambient temperature and are exothermic. Dienes are also hydrosilylated.223 The complexes also catalyze the hydrosilylation of butyne-1, phenylacetylene, butyne-2 and diphenylacetylene in 70-90% yield. The... 

Treatment of Pt3(CNBu )6 with diphenylcyclopropenone has produced the yellow diplatinum complex (58), in which cleavage of the carbon-car-... 

Oxidative activation of cyclopropenes is much less frequently encountered. The reactions of various platinum(O) complexes with the electron-deficient methylenecyclopropene 170 affords platinacyclobutene complexes, as reported nearly 30 years ago <1978ICA19>. More recent investigation has established that in the presence of two or more equivalents of the metal, bicyclic diplatinum complexes can be generated (Scheme 40) <1996JBS75>. 

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... 

More recently, also the tetraacetate diplatinum complex [Pt n(CH3C02)4(H20)2]2+ was prepared by refluxing a solution of K2[Pt(N02)4] in a 2 1 mixture of glacial acetic acid and 1m perchloric acid... 

POP- and PCP-Bridging Ligands. The pyrophosphite complexes are the most studied among lantern-type diplatinum complexes [6] [8] [73]. The Ptn complex [Pt2(H2P205 />,/>)4]4- is easily prepared by reaction of K2PtCl4... 

Synthesis and Characterisation of Electron-Deficient Hydrido and Methyl Diplatinum Complexes... 

A serendipitous discovery(6) that [Pt(cod)2] (cod cyclo-octa-1,5-diene) reacted with perfluoropropene to give the diplatinum complex [pt2 y-C(CF3)2 (cod)2], rather than the simple Ti2 adduct [Pt(CF2 CFCF3)(cod)], led to the idea(7) that mononuclear metal-carbene or -carbyne complexes would combine with nucleophilic and co-ordinatively unsaturated metal species (M") ... 

MejCHjPh, Me2Et or Etj] in toluene or light petrol is complete in under 2 h, and unusual hydrogen-bridged diplatinum complexes are formed ... 

Among the bridging ligands with the shortest bite distance are the oxygen-donor anions sulfate, phosphate (in the form of hydrogen and dihydrogen phosphate in the known quadruply bridged diplatinum complexes), and acetate. The acetate complexes will be discussed in the next section. 

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). 

The pyrophosphite (pop) complexes are the most thoroughly studied among lantem-type diplatinum complexes (6-8). The preparative... 

Table III classifies the bridging ligands by their bite distances and correlates them with the known oxidation states of the diplatinum complexes. When ligands with bite distances longer than ca. 2.7 A react with Pt(II) salts, Pt(II) complexes are obtained. On the contrary, in those cases with a shorter bite distance than 2.7 A, Pt(III) instead of Pt(II) dimers are obtained. Chlorine abstraction of [Pt2"(pyt)4] from chloroform to produce [Pt2 (pyt)4Cl2] is taken as an intermediate phenomenon, and the bite distance of ca. 2.7 A is considered a limit for...

Core vibrational frequencies obtained by Raman or resonance Raman spectrophotometric technique are summarized in Table V (53, 113, 116-118). The p(Pt—Pt) bands for the pop complexes [Pt2(pop)4] " (PtdDa), [Pt2(pop)4X] - (Ptdl,111)2), and [Pt2(pop)4X2] - (Pt(III)2) increase in the order expected from increasing Pt—Pt interaction (53). Resonance Raman spectra have been used frequently for the assignment of the electronic transitions of complexes as listed in the table. Also, observation of the vibrational structure in the low-temperature luminescence spectra coupled with the data in the table has been useful for considering the nature of the transition of these diplatinum complexes. The resonance Raman spectra at the intervalence band of the three mixed-valence complexes, which are stable only in the solid state, indicate that [Pt2(pop)4Cl] is a localized valence species and the bromo and iodo analogues are nearly delocalized valence species (53). 

Raman and Resonance Raman Bands (cm ) for the Lantern-Type Diplatinum Complexes... 

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