Bismuth(III) chloride complexation with diphosphine and diarsine oxide ligands: formation and crystal structures of [BiCl3{Ph2P(O)CH2P(O)Ph2}]2 and [BiCl3{As(O)MePh2}{Ph2As(O)Ch2CH2As(O)Ph2}]n

Abstract

The reactions of bismuth(III) chloride and Ph₂PCH₂PPh₂(dppm) and Ph₂AsCH₂CH₂AsPh₂-(dpae) have been studied. The yellow products isolated initially were characterised by spectroscopic (¹H and ³¹P NMR, IR) and microanalytical data as the 1:1 addition compounds BiCl₃·dppm and BiCl₃·dpae respectively. Recrystallisation of these products from boiling acetonitrile/charcoal effected oxidation of the ligands and resulted in the formation of two new molecular adducts whose structures have been determined by X-ray crystallography. Crystals of [BiCl₃{Ph₂P(O)CH₂P(O)Ph₂}]₂1 are triclinic, space group P with Z= 2. There are two independent centrosymmetric molecules in the unit cell with similar edge–edge shared bioctahedral structures. Each bismuth centre is six-co-ordinate with approximal octahedral geometry being bonded to two terminal chlorine atoms, two bridging chlorine atoms and two oxygen (ligand) atoms. In situ ligand oxidation dppm → Ph₂P(O)CH₂P(O)Ph₂ occurs and the resulting bidentate (OO′) chelation gives rise to puckered six-membered [graphic omitted] ring formation. Crystals of [BiCl₃{As(O)MePh₂}{Ph₂As(O)CH₂CH₂As(O)Ph₂}]_n2 are monoclinic, space group P2₁/a with Z= 4. The structure consists of one-dimensional polymeric chains. Here the in situ ligand oxidation is more complex and results in the formation of two arsine oxide ligands, viz. dpae → Ph₂As(O)CH₂CH₂As(O)Ph₂+ As(O)MePh₂ both of which are involved in co-ordination to Bi^III. Each bismuth atom is bonded in an approximately mer-octahedral arrangement to three terminal chlorine atoms and three oxygen (ligand) atoms. Of the latter, one is provided by a monodentate As(O)MePh₂ molecule and the other two by separate Ph₂As(O)CH₂CH₂As(O)Ph₂ molecules which, by virtue of their bidentate bridging mode, are linked to adjacent metal centres.