Stoeckli-Evans, Helen

2007, Ebrahim, Mothi Mohamed, Stoeckli-Evans, Helen, Panchanatheswaran, Krishnaswamy

The unsymmetrical phosphorus ylide, Ph₂PCH₂CH₂PPh₂=C(H)C(O)Ph is shown to react with Hg(II) halides to form polymeric products with the composition {HgX₂ [PPh₂CH₂CH₂PPh₂C(H)C(O)Ph]}_n, where X = Cl (1), Br (2), I (3). The complexes have been characterized by elemental analysis, IR, ¹H, ³¹P NMR spectra as well as by ESI mass spectra. In product 1 the ylide exhibits a P, C-bridging mode of coordination, while in 2 and 3 it shows a monodentate P-coordination with the dangling ylide. The structure of complex 3 has been characterized crystallographically. The monomeric –Hg–I–Hg– bridging in 3 leads to a zig-zag polymeric chain in which mercury assumes a distorted tetrahedral geometry.

2007, Ebrahim, Mothi Mohamed, Neels, Antonia, Stoeckli-Evans, Helen, Panchanatheswaran, Krishnaswamy

The reaction of mercury(II) halides with 1,2-bis(diphenylphosphino)ethane monoxide (dppeO) in 1:1 molar ratio yielded P,O-coordinated polymers having the empirical formula [HgX₂ (dppeO)]_n [X = Cl (1), Br (2), I (3)]. In contrast, the reaction between the same reactants in a 1:2 molar ratio yielded the P, P-coordinated monomeric complexes, HgX₂ (dppeO)₂[X = Cl (4), Br (5), I (6)]. The structures of 2, 3, 4 and 5 have been characterized crystallographically. The results indicate that the geometry around the mercury atom in each of these molecules is tetrahedral with considerable distortion. The 31P NMR spectra of the 1:1 complexes indicate the dissociation of the Hg–O bond in solution.

2007, Ebrahim, Mothi Mohamed, Stoeckli-Evans, Helen, Panchanatheswaran, Krishnaswamy

Organotin(IV) complexes of the type [RSnCl₃ (cis-Ph₂PCH=CHPPh₂)] [R = Me (1), ⁿBu (2), Ph (3)] were prepared by the reaction of RSnCl₃ with the rigid bisphosphine ligand, cis-1,2-bis(diphenylphosphino)ethylene in dichloromethane. The complexes have been characterized both in solution and the solid state. Low temperature ³¹P and ¹¹⁹Sn NMR studies indicate two different phosphorus environments. The crystal structures indicate a weak but chelating mode of coordination of the two phosphorus atoms to tin, leading to a distorted octahedral geometry. In solution the complexes 1–3 undergo a redistribution reaction to form [SnCl₄ (cis-Ph₂PCH=CHPPh₂)] (4) as one of the products. In order to confirm the redistribution, complex 4 has been prepared separately and characterized both structurally and spectrally.