The Crystal and Molecular Structure of trans-(Methyl)(but-2-yne)-bis(dimethylphenylphosphine)platinum(II) Hexafluorophosphate [(CH3)(H3CC≡CCH3)Pt(P(CH3)2]PF6

1973 ◽  
Vol 51 (21) ◽  
pp. 3477-3485 ◽  
Author(s):  
Brian W. Davies ◽  
Nicholas C. Payne

The crystal and molecular structure of trans-(methyl)(but-2-yne)bis(dimethylphenylphosphine)-platinum(II) hexafluorophosphate, [(CH3)(H3CC≡CCH3)Pt(P(CH3)2]PF6, has been determined from three dimensional X-ray diffraction data recorded by diffractometric methods. The structure has been refined by full-matrix least-squares methods on F using 1060 unique data to a conventional agreement factor R = 0.036. The crystals are orthorhombic, space group Pnma(D2h16), with a = 15.447(5), b = 15.344(4), c = 11.005(3) Å, and Z = 4. The coordination about the platinum atom is approximately square planar, if the acetylene is considered to be a unidentate ligand. There is crystallographic mirror symmetry imposed on the ions, such that the platinum atom, the methyl carbon atom, and the four carbon atoms of the acetylene ligand all lie on the mirror plane. The acetylene C≡C bond is approximately perpendicular (86.5(1.5)°) to the coordination plane of the platinum atom. The mean platinum–carbon(acetylene) bond length is 2.278(5) Å, and the mean angular departure from linearity of the ligand is 12(4)°. There is a small (156 cm−1) reduction of Vstr (C≡C) for the but-2-yne ligand upon coordination, and the acetylenic carbon–carbon bond length, 1.22(3) Å, is not significantly different from the value of 1.21(2) Å observed in the free ligand.

1972 ◽  
Vol 50 (14) ◽  
pp. 2276-2284 ◽  
Author(s):  
Brian W. Davies ◽  
Richard J. Puddephatt ◽  
Nicholas C. Payne

The crystal and molecular structure of trans-chloromethylbis(trimethylarsine)platinum(II) hexafluorobut-2-yne has been determined from three dimensional X-ray diffraction data recorded by diffractometric methods. The structure has been refined by full-matrix least-squares methods on F using 1156 reflections to an agreement factor R = 0.077. The crystals are monoclinic, space group [Formula: see text] with a = 6.803(8), b = 14.93(2), c = 20.20(2) Å, β = 104.9(1)°, and Z = 4. The coordination of the platinum atom is trigonal bipyramidal, with the acetylene considered a monodentate ligand, and the two trimethylarsine ligands occupying the equatorial plane. The chlorine atom and the methyl ligand occupy the apical positions, with Pt—Cl and Pt—C distances of 2.47(1) Å and 2.10(4) Å, respectively. The long Pt—Cl bond length indicates the strong trans-influence of the methyl ligand. The observed C—C bond length of 1.32(4) Å in the acetylene ligand is lengthened from the value of 1.22(9) Å measured in the free ligand. The geometry of the coordinated ligand is discussed in terms of the bonding scheme proposed by Greaves etal.


1981 ◽  
Vol 59 (15) ◽  
pp. 2364-2367 ◽  
Author(s):  
A. Wallace Cordes ◽  
Paul N. Swepston ◽  
Richard T. Oakley ◽  
Norman L. Paddock ◽  
T. N. Ranganathan

Crystals of the title compound are orthorhombic, a = 7.387(1), b = 8.502(2), c = 14.662(2) Å, Z = 4, space group Pnma. The structure was solved by direct methods and refined by least-squares procedures to a final R of 0.058, Rw = 0.097 for the 530 reflections with I > 3σ(I). The P3N3 ring is slightly but significantly non-planar with a crystallographically-imposed mirror plane normal to the ring, and the PN bond lengths in order from the PMe2 group are 1.601(7), 1.552(7), and 1.560(6) Å. The ring angles are 114.0(4)°, (PMe2); 120.0(4)°, PF2; 123.2(5)°, N(3); 119.6(5)°, N(4). The mean exocyclic bond lengths are P—C, 1.77(1), P—F, 1.522(6), and the exoangles are 107.4(4)° (PMe2) and 97.2(3)°, (PF2). The bond lengths within the ring are well described in terms of simple perturbation theory, but comparison with the structures of other molecules shows the importance of factors other than π-electron distribution.


1979 ◽  
Vol 57 (15) ◽  
pp. 1909-1914 ◽  
Author(s):  
Joseph C. Calabrese ◽  
Richard T. Oakley ◽  
Robert West

The crystal and molecular structure of the molybdenum tetracarbonyl complex of 1,4-diphenyl-2,2′,3,3′,5,5′,6,6′-octamethylcyclo-1,4-diphosph a-2,3,5,6-tetrasilahexane, (PhPSi2Me4)2Mo(CO)4, has been determined by single crystal X-ray diffraction. The crystals are monoclinic, space group P21/n, with a = 15.983(5), b = 19.316(6), c = 10.580(3) Å, β = 99.99(2)° V = 3217(2) Å3, Z = 4, and ρcalcd = 1.356 g/cm3. The structure was solved by Patterson heavy atom methods and was refined by full-matrix least-squares procedures to a final R1 of 3.3% and R2 of 4.3%, for 6342 reflections with intensities greater than 2σ. The coordination of the boat-shaped (PhPSi2Me4)2 ligand to molybdenum tetracarbonyl produces a distorted octahedral environment about the metal. The mean Si—Si (2.358(14) Å) and P—Si (2.275(19) Å) distances are not greatly altered from the values found for them in the free ligand. The structural consequences of P → Si π-bonding in the latter are therefore minimal. The relatively long P—Mo (mean length 2.592(13) Å) distances are interpreted as the result of reduced back-bonding from the metal, caused by the presence of the relatively electropositive silyl groups on phosphorus. Consistently, the equatorial Mo—C bonds, which are trans to the diphosphine ligand, are shorter (mean length 1.968(19) Å) than the corresponding bonds to the axial carbonyl groups (mean length 2.021(15) Å).


1975 ◽  
Vol 53 (16) ◽  
pp. 2413-2418 ◽  
Author(s):  
Harry P. Calhoun ◽  
Richard T. Oakley ◽  
Norman L. Paddock ◽  
James Trotter

Octamethylcyclotetraphosphazene is deprotonated by methyllithium to form carbanions, which react with methyl iodide to give ethyl derivatives N4P4Me8−nEtn, [Formula: see text] the structure of the dihydrochloride of the diethyl derivative, N4P4Me6Et2•2HCl has been determined. Its crystals are monoclinic, a = 9.928(5), b = 15.482(6), c = 6.329(2) Å, β = 103.29(2)°, space group P21/n. The structure was determined from diffractometer X-ray data and refined by full-matrix least squares methods to R 0.079 for 715 observed reflections. The N4P4Me6Et2H22+ ion lies on a crystallographic center of symmetry and the eight-membered phosphazene ring has the "chair" conformation. There are two significantly different P—N bond lengths, 1.665(6) and 1.572(7) Å, and two significantly different P—N—P angles, 126.7(6) and 139.8(6)°. The mean P—C bond length is 1.801(7) Å, and the mean N—P—N and C—P—C angles are 112.2(4) and 107.6° respectively. Bond lengths and angles in the phosphazene ring show the characteristic effects of π-electron localization found in other protonated phosphazene derivatives. The two ethyl groups are in tran-antipodal positions, corresponding to the least intramolecular electrostatic repulsion in the carbanion.


1999 ◽  
Vol 54 (10) ◽  
pp. 1313-1317 ◽  
Author(s):  
Qianfeng Zhang ◽  
Jinxi Chen ◽  
Maochun Hong ◽  
Xinquan Xin ◽  
Hoong-Kun Fun

Reaction of a DMF solution of Cu(S2CNC4H8) with [Ph4P]2[WSe4] affords [Ph4P]2[WSe4- (CuS2CNC4H8)3] (1) and [Ph4P][Cu(SeS2CNC4H )(S2CN2C4H8)] (2) in which a Se atom from the decomposition of the WSe42- anion has reacted with the pyrrolidyldithiocarbamate (C4H8dtc) ligand anion to form the new ligand anion SeS2CNC4H8⊖. Complex 2 crystallizes with four formula units in the monoclinic space group P21/c in a cell of dimensions a = 10.5824(2), b = 18.7575(3), c = 18.3268(4) Å and ß = 109.0980(10)°. 6055 independent reflections above background were measured with a diffractometer and the structure was refined anisotropically to R =0.073. The anion contains a three-coordinated copper(I) atom. The C4H8dtc⊖ ligand is bonded to the Cu+ cation in a terminal fashion, while SeS2CNC4H8⊖ chelates the Cu+ cation. The Se-S bond length is 2.231 (4) Å.


1979 ◽  
Vol 34 (1) ◽  
pp. 48-51 ◽  
Author(s):  
Jürgen Kopf ◽  
Klaus von Deuten ◽  
Bahman Nakhdjavan ◽  
Günter Klar

Abstract The structure of 2,8-dimethyldibenzo[c,g][1,2,5,6]tetrathiaocin (1b) has been determined by X-ray methods and discussed in connection with the preferred conformations of diaryl disulfides. The compound has the anti-form I. The SS-distance is 205.8 pm, the mean CSS-angle 104.1°, and the CSS/SSC-dihedral angle 111.1°.


1975 ◽  
Vol 28 (6) ◽  
pp. 1187 ◽  
Author(s):  
GR Clark ◽  
GJ Palenik

Crystals of 4-bromo-1,1,3,3,5,7,7,9,9- nonamethylbicyclo[4,4,0]pentaborophane, C9H35B5P5Br, are monoclinic, with a = 9.502(3), b = 20.185(15), c = 13.604(4) Ǻ, β = 116.49(2)�. The space group is P21/c, with four molecules in the cell. Intensity data were collected by means of an automated diffractometer. The atomic positions have been determined by least-squares refinement of 2859 observed reflections. The final residual, R, is 0.077. The molecule contains a framework of alternat- ing boron and phosphorus atoms constituting a decalin-like ring system. The two cis-fused cyclo- hexane type rings are both in the chair conformation. The bromine atom is equatorially bonded to the boron atom in the 4-position. The Br-B bond length is 2.039(10) Ǻ. The average P-B and P-C distances are 1.943 and 1.828 Ǻ respectively. Average internal ring angles are 112.2� for P-B-P, and 113.6� for B-P-B. This geometry indicates only very slight charge delocalization in the cyclic system.


1980 ◽  
Vol 33 (6) ◽  
pp. 1261 ◽  
Author(s):  
MA Bennett ◽  
S Corlett ◽  
GB Robertson ◽  
WL Steffen

The ligands (L) (E)-2,2'-bis(diphenylphosphino)stilbene, (E)-o-Ph2PC6H4CH=CHC6H4PPh2-o (bdps), (E)-1,3-bis[2-(diphenylphosphino)phenyl]propene, (E)-o-Ph2PC6H4CH=CHCH2C6H4PPh2-o (bdpp), and (E)-1,3-bis[2-(diphenylphosphino)phenyl]but-1-ene,( E)-o-Ph2PC6H4CH=CHCHMeC6- H4PPh2-o (bdpb), form complexes of general formula M(CO)3L (M = Cr, Mo, W). N.m.r. (1H, 13C and 31P) and i.r. data indicate that the metal atoms are octahedrally coordinated by mutually trans phosphorus atoms and the double bond of the olefinic tertiary diphosphines and by meridionally disposed carbonyl groups. Conformational isomers of the complexes of bdpb can be detected by n.m.r, spectroscopy, but there is no evidence for similar conformers in the corresponding complexes of bdps and bdpp. The crystal and molecular structure of W(CO)3(bdpp),0.5CH2C12 has been determined by single-crystal X-ray diffraction analysis. The crystals are triclinic, space group PI, with a 10.1 13(Z), b 13.820(2), c 14.512(3) A, α 76.24(1), β 88.08(1), γ 76.31(1)°. The structure, solved by the heavy-atom method and refined to a conventional R of 0.049 for 8418 diffractometer data, confirms the conclusions drawn from spectroscopic studies. The olefinic double bond of bdpp is attached symmetrically to the metal atom [W-C(olefin) 2.403(8), 2.387(9) Ǻ] and is roughly parallel to the P-W-P axis. The C=C bond length of 1.359(11) Ǻ is only slightly longer than that expected for the free ligand and is indicative of relatively weak metal-olefin back-bonding. Other important bond lengths are: W-P 2.450(2), 2.462(2) Ǻ and W-C(C0) 2.020(7), 2.024(7) Ǻ (CO trans to CO) and 1.971(7) Ǻ (CO trans to olefin).


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