Complexes of 1,3-Bis(diphenylphosphano)propane (dppp) with Dichloroplatinum(II) and Bis(chlorogold(I)): Intramolecular versus Intermolecular AuI-AuI Association of [(μ-dppp)(AuCl)2] incatena andcyclo Forms

Mechanistic insights into Ag+ induced size-growth from [Au6(DPPP)4]2+ to [Au7(DPPP)4]2+ clusters

The size conversion of atomically precise metal nanoclusters lays the foundation to elucidate the inherent structure-activity correlations on the nanometer scale. Herein, the mechanism of the Ag⁺-induced size growth from [Au₆(dppp)₄]²⁺ to [Au₇(dppp)₄]³⁺ (dppp is short for 1,3-bis(diphenylphosphino)propane) is studied via density functional theory (DFT) calculations. In the absence of extra Au sources, the one "Au⁺" addition was found to be regulated by the Ag⁺ doping induced Au-activation, i.e., the formation of formal Au(i) blocks via the Ag⁺ alloying processes. The Au(i) blocks could be extruded from the core structure in the formed Au-Ag alloy clusters, triggering a facile Au⁺ migration to the Au₆ precursor to form the Au₇ product. This study sheds light on the structural and stability changes of gold nanoclusters upon the addition of Ag⁺ and will hopefully benefit the development of more metal ion-induced size-conversion of metal nanoclusters.

Stereochemistry of Pt(η2-P2L)Cl2 derivatives

The coordination chemistry of platinum (Pt) covers a huge field as shown by a recent survey covering the crystallographic and structural data of almost 200 monomeric examples of the Pt(η2-P2L)Cl2type. About 20% of these complexes exist as isomers and are discussed in this review. Included are distortion (64%),cis-trans(20%), and ligand (16%) isomers. These are discussed in terms of the metallocyclic rings, and coordinations are drawn between donor atoms, bond lengths, and interbond angles, with attention to anytrans-influence. Distortion isomers, differing only by the degree of distortion in Pt-L and L-Pt-L angles, are the most numerous. In this series of distortion and ligand isomers, the square-planar configuration about the Pt(II) atom has onlycis-configuration. The total mean values of Pt-L bond distances (cis- vs.trans-configuration) are 2.228 Å (P) and 2.353 Å (Cl) vs. 2.312 (P) and 2.302 Å (Cl).

μ-1,3-Bis(diphenyl-phosphino)propane-κP:P']bis-[bromidogold(I)

The title compound, [Au(2)Br(2)(C(27)H(26)P(2))], features linearly coordinated Au(I) atoms within P,Br-donor sets. The central portion of the mol-ecule is practically planar as quanti-fied by the Br-Au⋯Au-Br torsion angle of -169.9 (2)°. The P-Au-Br chromophores are twisted with respect to each other [dihedral angle = 52.3 (6)°]. The benzene rings on each P atom lie on either side of this plane. The Au atoms are positioned at the periphery of the mol-ecule, which facilitates the formation of Au⋯Au inter-actions [3.2575 (11) Å] that result in the formation of supra-molecular chains along the b-axis direction. The Au⋯Au inter-actions are responsible for the deviations from the ideal linear geometry for each Au atom.

Di-platinum complexes containing thiolato-urea ligands: structural and anion binding studies

The new di-platinum(II) thiolato-bridged complexes [(dppp)Pt{micro-S(CH(2))(n)NHC([double bond, length as m-dash]O)NHR}](2)(OTf)(2) (n = 2, 3; R = Et, Ph) have been synthesized. The X-ray crystal structures of three of these complexes have confirmed their formulation and highlighted the ability of the urea groups on the thiolato bridges to display hydrogen bonding interactions with anions. The binding of anions by these receptors has been quantitatively determined by (1)H NMR spectroscopy and in a qualitative fashion by indicator displacement assays. These studies have shown the receptors to be selective for inorganic phosphate. In addition we have isolated and structurally characterized an unusual 1D coordination polymer with formula {[(dppp)Pt{micro-S(CH(2))(2)NHC([double bond, length as m-dash]O)NHR}][Pb(2)Cl(6)]}(n). The X-ray crystal structure of this inorganic polymer has shown that it consists of units of the di-platinum-thiolato cations bridged by [Pb(2)Cl(6)](2-) moieties.

Gold(I) chloride adducts of 1,3-bis(di-2-pyridylphosphino)propane: synthesis, structural studies and antitumour activity

The novel water soluble bidentate phosphine ligand 1,3-bis(di-2-pyridylphosphino)propane (d2pypp) has been synthesized by a convenient route involving treatment of 2-pyridyllithium with Cl(2)P(CH(2))(3)PCl(2) and isolation in crystalline form as the hydrochloride salt. The synthesis of the precursor Cl(2)P(CH(2))(3)PCl(2) has been optimized by the use of triphosgene as the chlorinating agent. The 2 : 1 and 1 : 2 AuCl : d2pypp adducts have been synthesized and characterized by NMR spectroscopy and single crystal X-ray studies, and shown to be of the form (AuCl)(2)(mu-d2pypp-P,P') and [Au(d2pypp-P,P')(2)]Cl(.3.75H(2)O), respectively. The latter is more lipophilic than analogous 1 : 2 adducts of gold(I) chloride with the diphosphine ligands 1,2-bis(di-n-pyridylphosphino)ethane (dnpype) for n = 2, 3 and 4, based on measurement of the n-octanol-water partition coefficient (log P = -0.46). A single crystal structure determination of the 1 : 2 Au(I) complex of the 3-pyridyl ethane ligand shows it to be of the form [Au(d3pype-P,P')(2)]Cl.5H(2)O. The in vitro cytotoxic activity of [Au(d2pypp)(2)]Cl was assessed in human normal and cancer breast cells and selective toxicity to the cancer cells found. The significance of these results to the antitumour properties of chelated 1 : 2 Au(I) diphosphine complexes is discussed.