Peter C. Chieh

Platinum cluster compounds: X-ray structures of phosphido-bridged bi- and tri-nuclear complexes with strong metal–metal bonds derived from [Pt(PPh3)4]

Binuclear [(Pt2(PPh3)2(PPh2)2] and trinuclear [Pt3(PPh3)2(PPh2)3Ph] cluster compounds of platinum have been prepared from [Pt(Ph3P)4] and characterised by X-ray crystal structure analyses of their benzene solvates.

The Interaction of Organomercury Pollutants with Biologically Important Sites: An X-ray study of the 2:1 Complex between Methylmercury and Penicillamine

The toxic pollutant methylmercurychloride forms 1:1 and 2:1 complexes with the sulfur amino acid DL-penicillamine. The mode of binding of the methylmercury by penicillamine has been established by a three-dimensional X-ray study of [CH3Hg]2(SC(CH3)2CHNH2COO).

Crystal and molecular structure of aquobis-(2,2′-bipyridyl)palladium dinitrate

Crystals of the title compound are monoclinic with a= 6·932(1), b= 26·721(6), c= 11·697(3)A, β= 103·4(1)°, space group P21/c, and Z= 4. The structure was determined from diffractometer data by Patterson and Fourier methods and refined by full-matrix least-squares techniques to R 0·060 for 2589 observed reflections. The structure consists of discrete Pd(bipy)22+ cations and nitrate anions. There is a weak interaction between the metal ion and one of the nitrate ions, the other nitrate ion being hydrogen bonded to a water molecule. The steric strain imposed by the interaction of interligand ortho-hydrogens is reduced by a distortion from a square planar configuration. The ‘bite’ of the 2,2′-bipyridyl ligand results in a rectangular distortion of the PdN4 skeleton such that mean of the angles N–Pd–N, where both nitrogens are from the same ligand, is 80·0(3)°. The corresponding angle involving nitrogens from different ligands is 102·2(3)°. There is also a mutual twist of the two ligands to avoid interligand hydrogen contacts. The mean diagonal angle, N–Pd–N, is 164·5(5)°. The torsion angle is 24·3°

Two-carbon three-electron ligands. Phosphonium–betaine complexes via nucleophilic attack by phosphites on a σ-π-acetylide di-iron hexacarbonyl derivative

Phosphonium–betaine (ylide–carbene) complexes have been synthesised via nucleophilic attack by P(OR)3 on a σ-π-acetylide complex Fe2(CO)6(CCPh)(PPh2), and a single crystal X-ray study of the triethylphosphite derivative Fe2(CO)6{C[P(OEt)3]CPh}(PPh2) has con-firmed the presence of a new type of 2-carbon, 3-electron ligand.

Syntheses, X-ray crystal structure, and vibrational spectra of L-cysteinato(methyl)mercury(II) monohydrate

The title complex has been prepared from the reaction of L-cysteine with methylmercury hydroxide or chloride in basic solution and characterised by single-crystal X-ray diffractometry. Crystals are orthorhombic, space group P212121, with unit cell dimensions a= 6·386(6), b= 26·026(13), c= 5·282(4)A and Z= 4. The structure was solved by Patterson and Fourier techniques and refined by full-matrix least-squares methods to a final R of 0·065 for 980 independent observed reflections measured on an automatic diffractometer. The amino-acid is co-ordinated to Hg via a deprotonated sulphydryl group [Hg–S 2·352(12)A]. A weak intramolecular Hg ⋯ O interaction [2·85(2)A] to a carboxylate group is present. Individual molecules of the complex are linked by hydrogen bonds to solvent water molecules. The vibrational spectra of the complex are discussed [ν(Hg–S) 326 cm–1].

Synthesis and X-ray structure of Fe2 (CO)6[P(C6F5)2][(C6F5)2PC4(C6H5)2]: A new type of organoiron complex containing a 3-electron donor phosphorus heterocycle

Abstract A new five-membered phosphorus heterocycle coordinated to two iron atoms in the binuclear complex Fe 2 (CO) 6 [(C 6 F 5 ) 2 PC 4 (Ph) 2 ]P(C 6 F 5 ) 2 is formed in the reaction of Fe 2 (CO) 9 with (C 6 F 5 ) 2 PCCPh. An X-ray structural study revealed that the heterocycle, a derivative of 1-bis(pentafluorophenyl)phosphonia-2,5-diphenyl-2,4-cyclopentadiene functions as a symmetrical dihapto , bridging 3 e ligand in I.

Steric effects in a distorted square planar bis-(2,2′-bipyridyl) metal complex: X-ray crystal structure of aquobis-(2,2′-bipyridyl)palladium(II) nitrate

The nature and magnitude of distortions induced by steric effects in a M(bipy)22+ cation have been elucidated by a single crystal X-ray structural determination of [Pd(bipy)2](NO3)2H2O.

Models for the methylmercury–protein interaction: a comparison of the molecular structures of methyl-L-cysteinatomercury(II) and methyl-DL-methioninemercury(II)

X-ray crystal structure determinations have shown that the essential amino-acid L-cysteine is bound to methylmercury(II)via a deprotonated sulphydryl group, whereas methionine is co-ordinated via an amino group in their respective 1 : 1 complexes.

Base-induced coupling of acetylenes held proximate to a metal: structures of unsymmetrical diphosphine complexes of platinum(II) containing strong vinyl alcohol–amine hydrogen bonds

The complexes cis-[Pt(Cl2)Y]·L [where Y = diphosphine Ph2P·CH:C(CF3)·C(PPh2):C(OH)·CF3: L = Et2NH, Et3N, Me3N, or Pr3N] have been synthesised by base-promoted coupling of phosphinoacetylene ligands in the complex cis-[PtCl2(Ph2PC⋮CCF3)2], and characterised by microanalysis, i.r. spectroscopy, and a single-crystal X-ray diffraction study of the diethylamine derivative (II). Crystals of (II) are monoclinic, space group P21/n, a= 18.707(13), b= 11.102(18), c= 19.383(13)A, β= 111.48(10)°, Dm= 1.60 g cm–3, Z= 4, Dc= 1.618 g cm–3. The structure was solved by conventional heavy-atom methods and refined to R 0.065 for 3 384 observed diffractometer intensity data. The molecule contains an unsymmetrical diphosphine ligand formed via dimerisation of two alkyne fragments. The molecule of diethylamine is strongly hydrogen bonded to the oxygen atom of a vinyl alcohol moiety in the diphosphine ligand [N ⋯ O 2.74(2)A]. Relevant metal–ligand distances are: Pt–Cl(1) 2.367(5), Pt–Cl(2) 2.357(5), Pt–P(1) 2.248(4), and Pt-P(2) 2.202(5)A. The i.r. spectra of all four complexes are similar and characteristic of hydrogen-bonded systems with predominantly ion-pair C–Ō⋯ H–[graphic omitted](H)Et2 character.

Crystal chemistry of tetraphenyl derivatives of group IVB elements

The crystal structures of the tetraphenyl derivatives of the Group IVB elements (MPh4; M = C, Si, Ge, or Sn) are compared. All are tetragonal, Z= 2, space-group P 21c, with symmetry. Parameters obtained from a new determination of the crystal structure of SiPh4 are in good agreement with those published earlier.