Platinum complexes alkynyl

Polynuclear assemblies can also be readily formed due to the ability of the alkyne ligands to form strong o-bonds with metals, as well as then-propensity for 71 coordination (t -fashion) (102) with electrophilic metal centers like Cu(I), Ag(I), and Au(I). Fornies and co-workers (44, 45, 103, 104) prepared interesting examples of di- and polynuclear alkynyl platinum complexes (Scheme 12). The [PtCu4(C=CPh)g] (105-107)... 

Intermolecular exchange of the alkynyl and halide ligands occurs in the presence of Gul, leading to conproportio-nation of the bisalkynyl complex 705 and dihalogenoplatinum complex, giving halo(alkynyl)platinum complex 706... 

The Pt(iv) complexes with cyclic -Pt-SnMc2—E-SnMe2—E- fragments (E = S, Se, Te) undergo insertion of dimethyl acetylenedicarboxylate into an E-Sn bond to form complexes with a seven-membered ring (950, Equation (181)). " The Pt-Sn-C=G-Sn metallacycle reacts further with alkyne to produce a vinyl(alkynyl)-platinum complex. 

Platinum complexes (continued) with aryls, thallium adducts, 3, 399 with bis(alkynyl), NLO properties, 12, 125 with bisalkynyl copper complexes, 2, 182-186 with bis(3,5-dichloro-2,4,6-trifluorophenyl), 8, 483 and C-F bond activation, 1, 743 in C-H bond alkenylations, 10, 225 in C-H bond electrophilic activation studies, 1, 707 with chromium, 5, 312 with copper, 2, 168 cyclometallated, for OLEDs, 12, 145 in diyne carbometallations, 10, 351-352 in ene-yne metathesis, 11, 273 in enyne skeletal reorganization, 11, 289 heteronuclear Pt isocyanides, 8, 431 inside metallodendrimers, 12, 400 kinetic studies, 1, 531 on metallodendrimer surfaces, 12, 391 mononuclear Pt(II) isocyanides, 8, 428 mononuclear Pt(0) isocyanides, 8, 424 overview, 8, 405-444 d -cP oxidative addition, PHIP, 1, 436 polynuclear Pt isocyanides, 8, 431 polynuclear Pt(0) isocyanides, 8, 425 Pt(I) isocyanides, 8, 425 Pt(IV) isocyanides, 8, 430... 

RE is the reverse of OA, whereby oxidation state, coordination number, and electron count all decrease, usually by two units. According to the principle of microscopic reversibility, the mechanistic pathways for RE are exactly the same as those for OA, only now in the reverse sense (this principle corresponds to the idea that the lowest pathway over a mountain chain must be the same regardless of the direction of travel). Equation 7.47 shows an example of RE from a platinum complex to give a silylalkyne." RE here likely goes through a concerted, three-centered transition state with both M-Si and M-C(alkynyl) bonds breaking and the new Si-C bond starting to form. 

Figure 2.17 Solvatochromic ionic cr-alkynyl platinum(II) terpyridine complexes...

Vicente and co-workers have recently synthesized platinum(n) 7 and mixed platinum(II)/ gold(I) a-alkynyl polymers 8.53 The monomers were prepared via dehydrohalogenation between c -[PtCI2( PR jb I and various alkynes. Polymerization occurred via the reaction of the platinum complex with PPN[Au(acac)2], giving polymers with mixed metal backbones. 

Exchange reactions of aryl and iodo ligands and of aryl and alkynyl ligands are not observed at all. Analogous alkynyl ligand transfer from aryl(alkynyl)palladium complexes to aryl(iodo)platinum complexes shown in Eq. 5.52 occurs above 35°C to cause complete alkynyl group transfer from Pd to Pt [183]. 

Alkynyl complexes contain metal-carbon bonds in which the metal is bound to the sp-hybridized carbon at the terminus of a metal-carbon triple bond. The materials properties of these complexes have been investigated extensively. The properties of these complexes include luminescence, optical nonlinearity, electrical conductivity, and liquid crystallinity. These properties derive largely from the extensive overlap of the metal orbitals with the ir-orbitals on the alkynyl ligand. The M-C bonds in alkynyl complexes appear to be considerably stronger than those in methyl, phenyl, or vinyl complexes. Alkynyl complexes are sometimes prepared from acetylide anions generated from terminal alkynes and lithium bases (e.g., method A in Equation 3.42), but the acidity of alkynyl C-H bonds, particularly after coordination of the alkyne to the transition metal, makes it possible to form alkynyl complexes from alkynes and relatively weak bases (e.g., method B in Equation 3.42). Alkynyl copper complexes are easily prepared and often used to make alkynylnickel, -palladium, or -platinum complexes by transmetallation (Equation 3.43). This reaction is a step in the preparation of Ni, Pd, or Pt alkynyl complexes from an alkyne, base, and a catalytic amoimt of Cul (Equation 3.44). This protocol for... 

Evidence for the role of bis(alkynyl)platinum(IV) species as precursors in catalytic processes has also been presented [13]. Complexes Pt(C=CR)2(COD) (R usually aryl, COD = 1,5-cyclooctadiene) exhibit useful properties as precatalysts for hydrosilylation reactions in cross-linking of polyorganosiloxanes containing Si-H and vinyl groups. Of particular value, the complexes are inactive as... 

Complex 2 (Eq. 1) and complex 11 in the reaction sequence shown in (Eq. 3) reported by James and coworkers [15] appear to be the only isolated bis(alkynyl) platinum(IV) complexes. Complex 11, assumed to have the configuration shown by analogy with 2 and related Ptl2Me2(bpy) (bpy = 2,2 -bipyridine), was obtained in quantitative yield and is stable over weeks in the solid state but slowly decomposes in solution by reductive elimination to form 12 (Eq. 3). The reaction of (Eq. 3) can be viewed as a suitable model for the chemistry of (Eq. 2), implicating Pt ... 

Stang and co-workers also demonstrated that reaction of platinum(0) complex 20 with alkynyliodonium triflate yielded alkynyl-platinum(II) complexes after careful optimization of the reaction conditions (Scheme 10, A) [92], Canty and co-workers... 

Dinuclear Pt complexes with bridging ethynediyl and polyynediyl ligands have been prepared by several reactions. The reaction of m-Pt(G6p5)2(CO)(THE) with a bis(trimethylsilylethynyl)platinum complex 805 results in transfer of one alkynyl ligand of 805 to produce a dinuclear complex 806 with an alkynyl ligand bonded to two Pt centers via cr- and TT-bonds (Scheme 107). The reaction of methanol with 806 and a direct reaction in methanol forms the dinuclear complex with a bridging ethynediyl ligand 807. 

Lang, H., and Stein, T. (2001). Bis(alkynyl)-Titaniiun and -Platinum Complexes in the Synthesis of Oligo- and Polynuclear Early-Late and/or Late-Late Transition Metal Species An Overview. Abhath Al-Yarmouk Basic Sci. Eng., 10, 155 Chem. Abstr. (2001), 142,38297. 

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