W. Kenneth Musker

Coordination chemistry of bidentate medium ring ligands (mesocycles)

Revieww of the coordination chemistry of mesocycles ligands and description of the most important properties of their complexes.

Preparation, properties and crystal structure of 1,2,5,6-tetrathiacyclooctane: The elusive mesocyclic bis-disulfide

Abstract The synthesis of the eight-membered ring containing two disulfides, 1,2,5,6-tetrathiacyclooctane, is described. It is characterized by x-ray crystallography as well as by mass, IR, Raman, 1 H-NMR und UV spectroscopy

Differences in the coordinating ability of water, perchlorate and tetrafluoroborate toward copper(I). The x-ray crystal structures of [Cu(1,4-thioxane)3OClO3], [Cu(1,4-thioxane)3OH2]BF4 and [Cu(1,4-thioxane)4BF4

SummaryCrystal structure determinations of the non-isomorphous salts, Cu(1,4-thioxane)3(ClO4) and Cu(1,4-thioxane)4(BF4) were carried out. The former compound was shown to contain strongly coordinated perchlorate while the later contains ionic tetrafluoroborate. For the coordinated perchlorate group, Cu-O is 2.278(8) Å. A third compound, Cu(1,4-thioxane)3(H2O)(BF4), was also characterized by x-ray crystallography, and contains a coordinated water molecule (with Cu-O 2.234(7) Å) that is hydrogen bonded to ionic tetrafluoroborate. All three complexes have approximately tetrahedral geometry. The copper(I) atom is coordinated to the sulfur atoms of the 1,4-thioxane rings. In each of the complexes, one of the 1,4-thioxane six-membered rings is coordinatedvia an equatorial ring position and the remaining two or three rings are coordinatedvia an axial position. The compound, Cu(1,4-thioxane)4(ClO4), was also prepared and found to be isomorphous with Cu(1,4-thioxane)4 (BF4), enabling a comparison to be made between the i.r. spectra of ionic and coordinated perchlorate in similar complexes.

Ultraviolet absorption spectra of some 2-substituted pyridines. σ-π conjugation involving group IV elements

Abstract This study reports the electronic spectra, in cyclohexane and 95% ethanol solvents, of some members of several series of 2-substituted pyridines containing Group IV elements. The compounds all contain the Group IV elements separated by a saturated carbon atom from the pyridine chromophore. The positions and intensities of both the 1Lb and 1La pyridine bands are sensitive to the substituents. The results are interpreted in terms of carbon-metal (σ-π) hyperconjugation.

Metal complexes of new chiral tridentate ligands with N, P and S donors : the crystal structure of [(S)-Ph2POCH2CH(NMe2)CH2CH2SCH3]W(CO)3

Abstract Two new ligands, ( S )-Ph 2 POCH 2 CH(NMe 2 )CH 2 CH 2 SCH 3 , derived from L -methionine, and ( R )-Ph 2 POCH 2 CH(NMe 2 )CH 2 -SCH 3 from L-cysteine have been prepared and characterized. Several metal complexes of Pd, Mo and W have been prepared. These ligands produce a chiral electronically asymmetric environment at the metal that is evidenced by trans influences on the other ligands. A crystal structure has been determined for [( S )-Ph 2 POCH 2 CH(NMe 2 )CH 2 CH 2 SCH 3 ]W(CO) 3 . The sulfur adopts an S s configuration in the solid and significant trans influences are observed in the metrical parameters of the carbonyls. This tungsten complex crystallizes in the monoclinic space group P 2 1 with a = 8.8435(6) A, b = 14.384(1) A, c = 9.546(1) A, β = 107.01(8), Z = 2 and V = 1161.0(4) A 3 .

SYNTHESIS AND STRUCTURE OF THE MESOCYCLIC COMPOUNDS, 5-PHENYL-l-THIA-5-PHOSPHACYCLOOCTANE, CIS- AND TRANS-1,5-DIPHENYL-1,5-DIPHOSPHACYCLOOCTANE AND THEIR PHOSPHINE OXIDES

Three 1.5-disubstituted eight-membered ring meSocycles, 5-phenyl-l-thia-5-phosphacyclooctane, 2, cis-and trans-1,5-diphenyl-1,5-diphosphacyclooctane. 5a and 5b, have been synthesized. The diastereomers 5a and 5b were separated by preparative HPLC and the stereochemical assignments confirmed by an X-ray crystal structure of 5b. The X-ray crystal structures of 5-phenyl-1-thia-5-phosphacyclooctane 5-oxide, 1, and trans-l,5-diphenyl-l,5-diphosphacyclooctane 1.5-dioxide, 3b, are also reported. MeSocycles 1, 3b and 5b are in the boat-chair conformation and are devoid of any indications of transannular interactions.

Structures of palladium(II) and nickel(II) complexes of the mesocyclic diphosphine, cis-1,5-diphenyl-1,5-diphosphacyclooctane

Abstract The preparation and X-ray crystal structures of a planar mono complex of cis- 1,5-diphenyl-1,5-diphosphacyclooctane with palladium(II) chloride and a pentacoordinated bis complex with nickel(II) chloride are reported. Dichloro(1,5-diphenyl-1,5-diphos- phacyclooctane)palladium(II) crystallizes in the monoclinic space group C2/c with cell constants a = 26.647(6), b = 7.884(1), c = 13,053(3) A, β = 98.15(2)° and Z = 4 at T = 130 K. Chloro-bis(1,5-diphenyl-1,5-diphosphacyclooctane)nickel(II) chloride crystallizes in the monoclinic space group P21/n with a = 18.178(7), b = 10.225(2), c = 20.959(7) A, β = 111.77(2)° and Z = 4 at T = 130 K.

Structure of a novel neutral lead(II) complex with dipropyldithiocarbamate

Abstract The synthesis and X-ray structure of a novel tetramer of Pb(II) with the dipropyldithiocarbamato ligand is described. The compound crystallizes in the triclinic space group P 1 with a =9.576(2), b = 14.151(4), c =16.175(4) A, α=104.84(2), β= 102.26(2), γ=90.62(2)°, V =2065(1) A 3 . Unit cell dimensions and data collection were done at 130(1) K using graphite-monochromated Mo Kα radiation. The conventional R factor is 0.030 for 5323 unique observed reflections with the goodness- of-fit parameter = 1.35. The structure consists of a sulfur-bridged neutral tetrameric species where each Pb(II) ion is pentacoordinated.

Preparation and X-ray crystal structure of the cyclic dimer of 1,2-dithiolane: 1,2,6,7-tetrathiacyclodecane

Abstract The synthesis and characterization by X-ray crystallography of 1,2,6,7-tetrathiacyclodecane is described. Two routes to the compound are given: (A) Treatment of 1,3-propanethiol with I2/triethylamine in CHCl3 under titrimetric high dilution conditions and (B) Oxidative cyclization of 1,5,6,10-tetrathiadecane. Recrystallization from hexane yields crystals (mp 131–132°C) belonging to space group P21/n with cell dimensions (at 140 K) of a [dbnd] 5.195(1), b = 12.446(3), c = 7.427(2) A, β = 106.45(2)°, Z = 2, πexptl (298 K) = 1.50 g cm−3. Solution and refinement of the structure gave a final R value of 0.033 using 70 parameters and 947 unique observed reflections.

Vibrational spectra of some cyclic polysulfides

Vibrational spectra and normal-coordinate analyses using a modified Urey-Bradley force field are reported for 1,2,3,5,6-pentathiepane (lenthionine), 1,3,5,7-tetrathiocane, and 1,2,3-trithiane. Characteristic Raman bands are identified for S-CH2-S and S-S-S functionalities in cyclic molecules.