Dibismuthates as Linking Units for Bis-Zwitterions and Coordination Polymers

Adducts of bismuth trihalides BiX₃ (X = Cl, Br, I) and the PS₃ ligand (PS₃ = P(C₆H₄-o-CH₂SCH₃)₃) react with HCl to form inorganic/organic hybrids with the general formula [HPS₃BiX₄]₂. On the basis of their solid-state structures determined by single-crystal X-ray diffraction, these compounds exhibit discrete bis-zwitterionic assemblies consisting of two phosphonium units [HPS₃]⁺ linked to a central dibismuthate core [Bi₂X₈]^2– via S→Bi dative interactions. Remarkably, the phosphorus center of the PS₃ ligand undergoes protonation with hydrochloric acid. This is in stark contrast to the protonation of phosphines commonly observed with hydrogen halides resulting in equilibrium. To understand the important factors in this protonation reaction, ³¹P NMR experiments and DFT computations have been performed. Furthermore, the dibismuthate linker was utilized to obtain the coordination polymer {[AgPS₃BiCl₃(OTf)]₂(CH₃CN)₂}_∞, in which dicationic [Ag(PS₃)]₂²⁺ macrocycles containing five-coordinate silver centers connect the dianionic [Bi₂Cl₆(OTf)₂]^2– dibismuthate fragments. The bonding situation in these dibismuthates has been investigated by single-crystal X-ray diffraction and DFT calculations (NBO analysis, AIM analysis, charge distribution).

The potential of dibismuthates [Bi₂X₈]²⁻ as building blocks for the synthesis of bis-zwitterions and coordination polymers has been shown. The structures of these compounds and the bonding in the dibismuthate linkers have been studied by single-crystal X-ray diffraction and DFT calculations.

Organophosphines in PtP4 derivatives; structural aspects

In this review, we classify and analyze the structural data of more than 80 monomeric platinum coordination complexes with an inner coordination sphere of PtP4 in which only organophosphines are involved. On the basis of the coordination mode of respective organophosphines, these complexes can be divided into six subgroups: Pt(PL)4, Pt(PL)2(PL′)2, Pt(η2-P2L)(PL)2, Pt(η2-P2L)2, Pt(η2-P2L)(η2-P2L′)2, and Pt(η4-P4L). The chelating ligands forming wide varieties of metallocycles: (P=P), (PNP), (PCP), (PC2P), (PP2P), (PC2NP), (PNCNP), (PNPNP), (POHOP), (POBOP), (PCNCP), (PC3P), (PC4P), and (PC2OC2P). The effects of both steric and electronic factors reflect on the values of P-Pt-P chelate angles. The total mean values of Pt-P elongate in the order: 2.289 Å (tetradentate)<2.306 Å (monodentate)<2.320 Å (bidentate). The same order shows the respective covalent bond weaknesses.

Monometallic Ni(0) and Heterobimetallic Ni(0) /Au(I) Complexes of Tripodal Phosphine Ligands: Characterization in Solution and in the Solid State and Catalysis

The tridentate chelate nickel complexes [(CO)Ni{(PPh2 CH2 )3 CMe}] (2), [(CO)Ni{(PPh2 CH2 CH2 )3 SiMe}] (6), and [Ph3 PNi{(PPh2 CH2 CH2 )3 SiMe}] (7), as well as the bidentate complex [(CO)2 Ni{(PPh2 CH2 )2 CMeCH2 PPh2 }] (3) and the heterobimetallic complex [(CO)2 Ni{(PPh2 CH2 )2 CMeCH2 Ph2 PAuCl}] (4), have been synthesized and fully characterized in solution. All (1) H and (13) C NMR signal assignments are based on 2D-NMR methods. Single crystal X-ray structures have been obtained for all complexes. Their (31) P CP/MAS (cross polarization with magic angle spinning) NMR spectra have been recorded and the isotropic lines identified. The signals were assigned with the help of their chemical shift anisotropy (CSA) data. All complexes have been tested regarding their catalytic activity for the cyclotrimerization of phenylacetylene. Whereas complexes 2-4 display low catalytic activity, complex 7 leads to quantitative conversion of the substrate within four hours and is highly selective throughout the catalytic reaction.

Tuneable reactivity with PPh3 and SnX2 of four- and five-coordinate Pd(II) and Pt(II) complexes containing polyphosphines

The reactivity of the unusual d(8) trigonal-bipyramidal systems [MX(PP3)]X (X = Cl: M = Pd(1a), Pt(2a); X = Br: M = Pd(3a), Pt(4a); X = I: M = Pd(5a), Pt(6a); PP3 = tris[2-(diphenylphosphino)ethyl]phosphine) in CHCl3-CH3OH, the square-pyramidal compounds [MCl(NP3)]Cl (M = Pd(7a); Pt(8a); NP3 = tris[2-(diphenylphosphino)ethyl]amine) in CD3OD-DMF and the distorted square-planar mononuclear [MX(PNP)]X (M = Pd: X = Cl(10a); M = Pt: X = I(10b); PNP = bis[2-(diphenylphosphino)ethyl]amine) and the heteronuclear [PdAu2X4(PP3)] [X = I(9a), Cl(14a), Br(15a)] and [MAuX2(PP3)]X [M = Pd: X = Cl(16a); M = Pt: X = Cl(17a), Br(18a)] species in CDCl3 with PPh3 + SnX2 has been explored to establish the factors that influence the nature of the products. With the mononuclear precursors the course of the reaction is strongly dependent on the tripodal or linear arrangement of the polydentate ligand and in the former case on the halogen. Thus, while for chlorides (1a-2a, 7a-8a) and bromides (3a-4a) the reaction led to the trigonal-bipyramidal compounds [M(SnCl3)(AP3)][SnCl3] [A = P: M = Pd(1), Pt(2); A = N: M = Pd(7), Pt(8)], [MBr(PP3)][SnBr3] [M = Pd(4), Pt(6)] containing M-Sn and M-Br bonds, respectively, for iodides (5a-6a) resulted in the unknown neutral square-planar compounds [MI2(PP(PO)2)(SnI2)2] [M = Pd(9) and Pt(10)] bearing two dangling P=O-SnI2 units and P2MI2 environments. However, complexes of the type [PtCl(PP2PO)X]X' [X = SnCl2, X' = [SnCl3](-)(11)] and [M(PP(PO)2)2X4]X'2 [X = SnCl2, X' = [SnCl3](-): M = Pd(12), Pt(13)] showing P=O-SnCl2 arms were obtained by direct reaction of [PtCl(PP2PO)]Cl (11a) and [M(PP(PO)2)2]Cl2 [M = Pd(12a), Pt(13a)] with SnCl2 in CH3OH. Although complex 9 was also prepared by interaction of the heteronuclear iodide 9a with PPh3 + SnI2 in CDCl3, the use of the neutral and ionic heteronuclear chlorides and bromides (14a-18a) as starting materials afforded the distorted square-planar ionic systems [MAuX'(PP3)(PPh3)][SnX3]2 [M = Pd: X = Cl, X' = SnCl3(-)(14); X = Br, X' = SnBr3(-)(15); M = Pt: X = Cl, X' = SnCl3(-)(17); X = Br, X' = SnBr3(-)(18)] containing M-SnX3 and P-Au-PPh3 functionalities. It was found that these reactions where the heteronuclear species are the precursors proceed via the trigonal-bipyramidal halides not only with X = Cl and Br(1a-4a) but also I(5a). When the precursors were 10a and 10b the reaction occurred with formation of [Pd(PNP)(PPh3)][SnCl3]2 (23) and [Pt(PNP)(PPh3)][SnCl2I]2 (24) showing M-PPh3 units and trihalostannato counter anions.