Xin-Min Gan

Synthesis and coordination chemistry of arene soluble 4-alkyl-2,6-bis[(diphenylphosphino)methyl]pyridine N,P,P′-trioxide ligands

The trifunctional ligand 2,6-[(C6H5)2P(O)CH2]2C5H3NO forms stable complexes with trivalent and tetravalent f-element cations and it acts as an effective liquid–liquid extraction reagent when it is dissolved in CHCl3. In a search for more hydrocarbon solvent soluble extraction reagents, derivative ligands having alkyl substituents in the 4-pyridyl ring position, 4-R′-2,6-[(C6H5)2P(O)CH2]2C5H2NO (R′ = Et, Oct), have been prepared and characterized. A single crystal X-ray diffraction analysis for the Et derivative shows that the ligand molecular structure is closely related to the parent ligand, 2,6-[(C6H5)2P(O)CH2]2C5H3NO. The coordination chemistry of the ligands with Nd(NO3)3 has been examined, and the molecular structures of two complexes obtained with 1 ∶ 1 and 2 ∶ 1 ligand ∶ metal reactant ratios are reported.

Synthesis and coordination properties of 6,6′-bis(diphenylphosphinomethyl)-2,2′-bipyridine-N,N′,P,P′-tetraoxide

The ligand 6,6′-(bis(biphenylphosphinomethyl)-2,2′-bipyridine-N,N′,P,P′-tetraoxide (7) is prepared by oxidation of the parent phosphine 6,6′-bis(diphenylphosphinomethyl)-2,2′-bipyridine (10). Combination of the oxidized ligand with lanthanide nitrates Ln(NO3)3·(H2O)n (Ln = La, Pr, Nd, Dy, Er) results in formation of 2:1 metal:ligand complexes, and the molecular structure of one complex, [Nd(7)2](NO3)3·[(CH3)2NC(O)H]2, is described. The compound crystallizes in the monoclinic space group C2/c with a = 20.617(4), b = 22.736(6), c = 18.465(3) A, β = 98.35(1)° and Z = 4. The molecular structure confirms the bis-ligands stoichiometry and shows that the two ligands are tetradentate. The Nd coordination number is eight, and the NO3− ions and solvent molecules are not involved in inner sphere coordination.

Synthesis of trifunctional ligands containing thiophosphoryl, pyridine and pyridine N-oxide donor groups

The trifunctional mixed donor ligands 2,6-[R2P(S)CH2]2C5H3N 1 (R = Ph 1a, Tol 1b, n-Bu, 1c) and 2,6-[R2P(S)CH2]2C5H3NO 2 (R = Ph 2a, Tol 2b, n-Bu, 2c) have been prepared and characterized by spectroscopic (MS, IR, NMR) techniques. The coordination chemistry of one derivative 1a has been examined and the complex {[Ph2P(S)CH2]2C5H3N}Ni(NO3)2 has been crystallized and characterized by single-crystal X-ray diffraction methods. The structure contains a six coordinate Ni(II) ion bonded to a tridentate ligand 1a with Ni–Npyr 2.110(3) A and Ni–S 2.481(1) and 2.402(1) A, a bidentate nitrate anion and a monodentate NO3− anion.