Robert Bender

Complexes organometalliques a liaisons metal—metal : XIII. Preparation de clusters heterotetrametalliques platine—molybdene et platine—tungstene et structure cristalline de Pt2Mo2(η5-C5H5)2(CO)6[P(C2H5)3]2

Abstract The cluster compounds Pt2M2(η5-C5H5)2(CO)6L2 (M ue5fb Mo, W; L ue5fb PEt3, PPh3) have been prepared from cis-PtCl2L2 and NaM(CO)3Cp. They are characterized by a planar, triangular, centrosymmetric arrangement of the metal atoms and by strongly asymmetric carbonyl bridges, which is shown by the crystal structure determination of Pt2Mo2(η5-C5H5)2(CO)6(PEt3)2.

Electronic and steric effects in closely related heteronuclear clusters. Selective pathways in synthetic and catalytic bimetallic chemistry

Abstract Comparisons are made between closely related heteronuclear clusters whose compositions only differ by the nature of a metal fragment or a ligand. Thus, addition of electrophilic d10 metal fragments to the Co3 face of the tetrahedral ruthenium-cobalt cluster [RuCo3(CO)12]− affords new clusters in which the variation of the distance between the Ru capping atom and this face shows that electronic communication takes place between the apices of the trigonal bipyramid. This allows the establishment of the trans-influence series: Cu(PPh3)

Unexpected bonding similarities between the bridging metalloligands [MoCp(CO)3]− and [PtI(CO)2(PPh3)]− acting as 4-electron donors in metal clusters. Crystal structures of [Pt2Mo(μ-CO)3- (μ-PPh2)Cp(PPh3)2] and [Pt3(μ-CO)2(μ-PPh2)I(PPh3)3]

Reactions of the diplatinum complex n[Pt2(μ-H)(μ-PPh2)I2(PPh3 n)2] with the carbonylmetalates n[MCp(CO)3]− (M = Mo, W) or n[Co(CO)4]− afforded the new 44e clusters n[Pt2M(μ-CO)3(μ-PPh2)Cp(PPh3 n)2] (M = Mo, 2; M = W, ,3) and n[Pt3(μ-CO)2(μ-PPh2)I(PPh3 n)3] 5, respectively, whose structures can be analysed as nformed by a 26e n[Pt2(μ-PPh2)(PPh3)2]+ n cation and a bridging, 4e donor anion, n[MCp(CO)3]− in 2 and 3, or the new 18e fragment n[PtI(CO)2(PPh3)]− in 5.

Reactivity of phosphido-bridged diplatinum complexes towards electrophiles: synthesis of new hydrides and related Pt2Cu and Pt2Ag clusters

The doubly-bridged, dinuclear complex [Pt2(μ-PPh2)(μ-o-C6H4PPh2)(PPh3)2] (1) reacts with electrophiles such as H+ or [M(PPh3)]+ n(M = Cu, Ag, Au) first at the metal–metal bond. This is supported by an X-ray diffraction study of [Pt2{μ-Cu(PPh3)}(μ-PPh2)(μ-o-C6H4PPh2)(PPh3)2]PF6 (2) which reveals a Pt2Cu triangular metal core and, unexpectedly, a bonding interaction between the Cu atom and the Cipso of the orthometalated phenyl. This confers a tetrahedral-like geometry to the Cu atom. In the neutral complex [Pt2{μ-AgOC(O)CF3}(μ-PPh2)(μ-o-C6H4PPh2)(PPh3)2] (3), the silver atom is coordinated by the terminally bound trifluorocarboxylate anion. Reactions of 1 in a polar solvent with 2 equiv. of acid HA, where A is a weakly nucleophilic anion, afforded the dicationic solvento adducts [Pt2(μ-H)(μ-PPh2)(Solv)(PPh3)3]A2 n(5a, Solv = THF, A = PF6; 5b, Solv = CH2Cl2, A = BF4; 5c, Solv = acetone, A = BF4) which result from rupture of the Pt–C σ bond and transformation of the cyclometalated bridging ligand into PPh3. The coordinated solvent molecule is readily displaced by nucleophiles such as PO2F2−, CF3SO3−, Cl− or Br−, thus forming monocationic complexes, 6–9, respectively. An X-ray diffraction study on [Pt2(μ-H)(μ-PPh2)(OPOF2)(PPh3)3](PF6)·0.5CH2Cl2 n(6·0.5CH2Cl2) establishes that the OPOF2 group is linked by one O atom to platinum, to our knowledge an unprecedented feature.