Neuartige basische Liganden für die homogenkatalytische Methanolcarbonylierung, XXI [1] Synthese und Eigenschaften von (Ether-Phosphan)-Platin-Komplexen / Novel Basic Ligands for the Homogenous Catalytic Methanol Carbonylation, XXI [1] Synthesis and Properties of (Ether-Phosphane) Platinum Complexes

Abstract

The (ether-phosphane) complexes cis-Cl2Pt(Ph2P∼D )2 (2a, b) [D = CH2C4H7O (a). C H2C4H7O2 (b)] are obtained by reaction of Ph2P∼D (1a , b) with either K2PtCl4 or Cl2Pt(COD) (COD = 1,5-cyclooctadiene). Both Cl- anions are abstracted from 2a, b using AgSbF6 to give the cationic bischelate complexes (5a, b). The stepwise cleavage and reform ation of Pt-O bonds in (ether-phosphane) platinum complexes is demonstrated bv the sequence (6a) → [trans-(Ph2P∼D )2PtCO(Cl)][SbF6] (7 a )→5a, when 5a, 6a, and 7a are reacted with KCl, CO, and AgSbF6 respectively. Reduction of 2a with NaBH4 results in the formation of trans-H2Pt(Ph2P∼D)2 (4a). In the presence of HCl 2a is reformed. Excess NaBH4 or heating of 4a yields the bischelate platinum(0) complex (3a), which is also isolated by reduction of 2a with sodium amalgam. A general method for obtaining (3a-c) [D = CH2CH2O CH , (c)] is the substitution of COD in Pt(COD)2 by the ether-phosphanes 1a-c. The structures and bonding properties of the compounds 2-7 are discussed on the basis of their 31P{1H } NMR and IR spectra.