Binuclear platinum(II) complexes containing 1,1,4,7,10,10-hexaphenyl-1,4,7,10-tetraphosphadecane (P4): first X-ray structure of a tetraphos dimer
摘要:
Several binuclear Pt(II) complexes containing 1,1,4,7,10,10-hexaphenyl-1,4,7,10-tetraphosphadecane (tetraphos-1, P4) have been prepared and characterized by (P{H})-P-31-H-1 NMR spectroscopy, elemental analyses, melting points and an X-ray structure analysis. In the first steps of the syntheses complexes of the general formula rac- or meso-[Pt2Cl3P4]X (X=Cl-, (BF4-), (BPh4-)) (1-6) showing a cis P4 arrangement are formed. Transformation to thermodynamically more stable compounds (1a-6a) leads to the incorporation of the chloride anion in cis, rac- or cis, meso-[Pt2Cl4P4] (1a, 2a). The X-ray structure of 1a, which is the first structure of a tetraphos dimer, has been determined (tetragonal, P42(1)cBAR; a=17.257(2), c=16.048(3) angstrom, R=0.048 for 1107 observed reflections (F>6.0-sigma(F)). It shows an open-mode dimer with a Pt-Pt distance of 6.338(1) angstrom and a cis P4 configuration. In the presence of non-coordinating anions a rearrangement of P4 from cis to trans occurs (3a-6a). The observation that P4 is able to coordinate two metal centers in a cis as well as in a trans manner is unusual for binuclear oligophosphine complexes.