Synthesis and Coordination Chemistry of 1,3-Bis(diphenylphosphinomethyl)benzene P,P‘-Dioxide

Rhenium(I)-Based Monocyclic and Bicyclic Phosphine Oxide-Coordinated Supramolecular Complexes

Neutral, flexible ditopic phosphine (P-P) or phosphine oxide (O=P-P=O) donors, rigid anionic bis-chelating oxygen donors, and Re₂(CO)₁₀ were used to assemble ten phosphine oxide (P=O)-donor-based neutral monocyclic M₂LL'-, bicyclic M₄L₂L″-, and bicyclic M₄LL'₂-type supramolecular coordination complexes (SCCs). A soft ditopic phosphine donor was transformed into a hard ditopic phosphine oxide donor, during the formation of the cyclic complexes 1-3, 5-6, and 9-10. Complexes 4, 7, and 8 were obtained using a hard P=O donor ligand. These SCCs were characterized using elemental analysis, FTIR, NMR, and single-crystal X-ray diffraction analysis. The absorption properties of 1-8 were studied using absorption UV-vis spectroscopic methods, and the results were analyzed using theoretical calculations. The results revealed that the neutral P=O donor significantly influenced the photophysical properties by enhancing the absorption coefficient in the visible region.

Pyrrole-based new diphosphines: Pd and Ni complexes bearing the PNP pincer ligand

A new class of diphosphine PNP pincer ligand, 2,5-bis(diphenylphosphinomethyl)pyrrole 2, was synthesized by the reaction between Ph2PH and 2,5-bis(dimethylaminomethyl)pyrrole in 90% yield. The analogous reaction of Ph2PH with 1,9-bis(dimethylaminomethyl)diphenyldipyrrolylmethane readily afforded a PNNP type diphosphine ligand, 1,9-bis(diphenylphosphinomethyl)diphenyldipyrrolylmethane 5 in 92% yield. These phosphine compounds were oxidized with H2O2 and S8 to give the corresponding phosphoryl and thiophosphoryl compounds 6-9 in very good yields. The reaction of the PNP pincer ligand 2 with [PdCl2(PhCN)2] in the presence of Et3N afforded the mononuclear Pd(II) complex, [PdCl{C4H2N-2,5-(CH2PPh2)2-κ(3)PNP}] 10 in 87% yield. Conversely, treatment of 2 with [PdCl2(PhCN)2] in the absence of Et3N gave the dinuclear Pd(II) complex [Pd2Cl4{μ-C4H3N-2,5-(CH2PPh2)2-κ(2)PP}2], the structure which is proposed based on the spectroscopic data. When 2 was treated with Pd(0) precursor [Pd2(dba)3]·CHCl3 the dinuclear Pd(I) complex [Pd2{μ-C4H2N-2,5-(CH2PPh2)2-κ(2)PN,κ(1)P}2], 12, was obtained in 23% yield. The formation of complex 12 is solvent dependent, which transforms into complex 10 in CDCl3 as studied by variable temperature (1)H and (31)P NMR methods. Treatment of 2 with [Ni(OAc)2]·4H2O gave the mononuclear Ni(II) pincer complex [Ni(OAc){C4H2N-2,5-(CH2PPh2)2-κ(3)PNP}], 13, which upon treatment with an excess of LiCl or LiBr or KI afforded the respective halide ion substituted Ni(II) complexes, [NiX{C4H2N-2,5-(CH2PPh2)2-κ(3)PNP}] (X = Cl, Br, and I), 14-16, in very good yields. The structures of 5, 2,5-bis(diphenylphosphorylmethyl)pyrrole 6, 10, 12, and 14-16 were determined by the single crystal X-ray diffraction method. In the structure of 12, two short contacts between the diagonally positioned Pd and P atoms are observed. To understand these weak interactions, density functional theory (DFT) calculations were done and an interaction MO diagram is presented.

Hydrogen Bonded Framework Structures Constructed from 2-(Pyridyl N-oxide) Methylphosphonic Acid Ligands and Erbium(III)

Syntheses for 2-(pyridyl N-oxide) methylphosphonic acid, 1-H, and 2-(pyridyl N-oxide) hydroxymethylphosphonic acid, 4-H, are described, and the crystal structures of both ligands are presented. Combination of these ligands with freshly prepared erbium hydroxide results in the formation of the isostructural complexes Er(L(-))(3)(LH).8H(2)O. The crystal structure determinations of the complexes show that extensive hydrogen bonding links the individual eight coordinate Er(L(-))(3)(LH) molecular units into a 3-D structure.

Complexes of lanthanide nitrates with bis(diphenylphosphino)methane dioxide

The reactions of lanthanide nitrates, Ln(NO(3))(3), with bis(diphenylphosphino)methane dioxide, Ph(2)P(O)CH(2)P(O)Ph(2) (L), lead to complexes with three distinct classes of structure. At low ratios of Ln:L (<1:1.5) in acetonitrile the ionic complexes [Ln(NO(3))(2)L(2)](+)[Ln(NO(3))(4)L](-) (Ln = Pr, Eu) have been isolated. When carried out with a 1:2 or higher ratio in ethanol the reaction yields Ln(NO(3))(3)L(2) (Ln = La,Ce) and [Ln(NO(3))(2)L(2)H(2)O](+)[NO(3)](-) (Ln = Nd, Gd, Ho). Geometrical isomerism is found for the cations [Ln(NO(3))(2)L(2)H(2)O](+) and is attributed to the extent of hydrogen bonding to the coordinated water. Ligand redistribution occurs on heating in the solid state giving yellow solids in all cases. Crystallization of these materials from ethanol or acetonitrile gives [Ln(NO(3))L(3)](2+).2[NO(3)](-), which have been structurally characterized for Ln = Gd and Yb. Electrospray mass spectra indicate that extensive ligand exchange reactions occur in solution.

Synthesis and coordination chemistry of 2,6-bis(diphenylphosphinomethyl)phenol P,P'-dioxides

The 2,6-bis(diphenylphosphinomethyl)phenol-P,P'-dioxides, [Ph(2)P(O)CH(2)](2)C(6)H(2)(R)OH, with R = H (2a), Br (2b), Me (2c), (t)Bu (2d), were prepared via Arbusov reactions between Ph(2)POEt and the phenol derivatives (ClCH(2))(2)C(6)H(2)(R)OH. The compounds have been characterized by spectroscopic methods, and their coordination chemistry with lanthanide nitrates, Ln(NO(3))(3), has been surveyed. The 1:1 complexes [Er(2c)(NO(3))(3)].Me(2)CO and [Nd(2d)(NO(3))(3).Me(2)CO].Me(2)CO have been structurally characterized by single-crystal X-ray diffraction methods, and the ligands found to act as neutral tridentate chelates. No evidence was found for the formation of 2:1 L:M complexes suggesting that these derivatives of 2 are weaker chelators than the related 2,6-bis(diphenylphosphinomethyl)pyridine N,P,P'-trioxide chelates.