87350-91-2Relevant academic research and scientific papers
Structural characterization of the head-to-head isomers of the [Pd2(Ph2Ppy)2Cl2] and [PtPd(Ph2Ppy)2I2] complexes (Ph2Ppy = 2-(diphenylphosphino)pyridine)
Párkányi, László,Szalontai, Gábor,Besenyei, Gábor
, p. 2933 - 2941 (2008/10/09)
The molecular structures of the thermodynamically unstable head-to-head isomers, HH-[Pd2(Ph2Ppy)2Cl2] and HH-[PtPd(Ph2Ppy)2I2], have been determined by single crystal X-ray diffraction. The two complexes have proved to be isostructural. The severe distortions of the bond angles from the ideal square planar geometry around the metal centers ligating the trans phosphorus donor atoms are indicative of a more pronounced internal strain in the HH isomers as compared to the HT counterparts. The enhanced internal strain is thought to be the major driving force responsible for the spontaneous conversion of the head-to-head isomers to their head-to-tail congeners. 13C NMR spectra in solution phase as well as solid-state 31P MAS NMR spectra have proved to be informative regarding the orientation of the asymmetric Ph2Ppy ligands.
Head-to-head and head-to-tail isomers of binuclear complexes of platinum(I) and palladium(I) involving 2-(diphenylphosphino)pyridine as a bridging ligand
Farr, James P.,Wood, Fred E.,Balch, Alan L.
, p. 3387 - 3393 (2008/10/08)
Reaction of Pt(Ph2Ppy)2Cl2 (Ph2Ppy is 2-(diphenylphosphino)pyridine) with Pd2(dba)3·CHCl3 (dba is dibenzylideneacetone) or Pt(dba)2 yields PtPd(μ-Ph2Ppy)2Cl2 or Pt2(μ-Ph2Ppy)2Cl2, respectively. Extensive 31P{1H} and 195Pt{1H} NMR studies show these exist as the head-to-tail (HT) isomers where the phosphorus atoms are bound to different metal atoms. Metathesis of Pt2(μ-Ph2Ppy)2Cl2 with sodium iodide yields the HT isomer of Pt2(μ-Ph2Ppy)2I2. Treatment of Pt(Ph2Ppy)2I2 with Pd2(dba)3·CHCl3 or Pt(dba)2 yields PtPd(μ-Ph2Ppy)2I2 or Pt2(μ-Ph2Ppy)2I2, respectively. These exist as the head-to-head (HH) isomers with both phosphines bound to the same platinum atom through phosphorus. The HH → HT isomerization of PtPd(μ-Ph2PPy)2I2 occurs on heating the HH complex in chloroform solution. In order to account for the selective preparation of HT isomers from Pt(Ph2PPy)2Cl2 and the formation of HH isomers from Pt(Ph2Ppy)2I2, the solution composition of these two Pt(II) complexes has been examined. In solution, Pt(Ph2Ppy)2I2 exists as a mixture of cis and trans isomers along with the salt [Pt(Ph2Ppy)2I]I while Pt(Ph2Ppy)2Cl2 exists as the cis isomer and the salt [Pt(Ph2Ppy)2Cl]Cl. These salts contain one chelating and one monodentate phosphorus-bound Ph2Ppy. An explanation for the selective formation of HT or HH isomers is offered.
