Pt bis-acetylide

Polymers of type B in which different kinds of metals are arranged alternately in the backbone are synthesized by an appropriate combination of monomers containing mixed metals41. Thus, a combination of a Pt-bis-acetylide and a diehloro-Pd monomer leads to the formation of the expected polymer containing regular arrangements... 

P NMR spectroscopy has also provided an exceptional tool for the determination of the configuration at the metal centers in polymers as well as oligomers [3-7, 10]. For example, the trans configuration of phosphine ligands in Pt-bis(acetylide) com-... 

In some cases structural effects could give indications about the type of mechanism. Ziessel et al. [49, 103] have used the Pt bis-cr-acetylide spacer to construct two isomeric binuclear complexes, cis (8) and trans (9) forms, with different metal-to-... 

Figure 4. Molecular photochemical device prototype (a) and chiral metallacyclophane for asymmetric catalysis (b) based on bis(acetylide)Pt(II) compounds.

The solvatochromic behaviour of the absorption spectra of complexes of this type illustrated in Fig. 3.9 is a further proof of the charge-transfer nature of the lowest electronic transition. Differently to thiolate or catecholate complexes, the lowest excited state in the bis-acetylide complexes Pt(diimine)(C = C-R)2 (R = 4-X-CeH4 ) mentioned above is a charge-transfer from the largely Pt based HOMO to the Pt/diimine-based LUMO. Consequently, the effect of electron donating properties of the acetylide ligand has much lesser influence on the redox and optical properties of the complexes [29, 30, 51] if compared to thiolate ligands. 

The extended Hiickel method, which is a semiempirical quantum chemistry method, is often used as a preliminary step in the DFT study of molecular orbital analysis. The acetylide-bridged organometallic dinuclear complexes 5.2 were studied by Halet et al. using the extended Hiickel method for qualitative analysis and DFT for additional electronic properties [97], The extended Hiickel analysis concluded that the main contribution of the Pt-C bond arises from ct type interactions while the n back-donation is very weak. The DFT/BP86 calculation gives a 2.371 eV HOMO-LUMO gap. The electronic communication parameter Hdb between the bis-ferrocene compound linked with platinum acetylide (5.3) was calculated to be 0.022 eV, compared with 0.025 eV obtained experimentally by Rapenne and coworkers using DFT and the extended Hiickel method [98],... 

The first anionic polymetallayne of gold(I), P83, was prepared in moderate yield (36%) from the reaction of PPN[Au(acac)2] (PPN = bis(triphenylphosphine)iminium) with 1,3-diethynylbenzene in a 1 1 stoichiometric ratio.104 It was characterized by IR and H NMR spectroscopies. More interestingly, efforts were made to make two novel anionic heteronu-clear Pt(II)-Au(I) cr-acetylide polymers exhibiting both the linear (P84) and branched (P85) forms, but these polymers possessed very poor solubility in all common organic solvents.105... 

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