Exceptionally Symmetric Crystal Structure of (Pentabenzylcyclopentadienyl)(cyclooctatetraene)titanium(III)

2004 ◽  
Vol 69 (11) ◽  
pp. 2036-2044 ◽  
Author(s):  
Ivana Císařová ◽  
Vojtech Varga ◽  
Michal Horáček ◽  
Jiří Kubišta ◽  
Karel Mach

Complex [Ti(III)(η8-C8H8)(η5-C5Bn5)] (1) was prepared by salt metathesis reaction of [TiCl(η8-C8H8)(thf)]2 with LiC5Bn5 and characterized by ESR and UV-near-IR spectra. Its crystal structure is symmetric with respect to a mirror plane involving the titanium atom and one of the benzyl groups.

1996 ◽  
Vol 74 (11) ◽  
pp. 2121-2130 ◽  
Author(s):  
Fernande D. , ◽  
Corinne Bensimon ◽  
André L. Beauchamp

Complexes of the type [Pt(L)Cl3]− (L = pyridine derivative) were synthesized and studied by 13C and 195Pt NMR spectroscopies. The 195Pt signals were observed between −1720 and −1897 ppm. No correlation between the δ(Pt) and the pKa of the protonated pyridine derivatives was found. The chemical shifts vary with the substituents on the pyridine ligand. Compounds with substituents in ortho positions were observed at lower fields, except for complexes containing hydroxy or amine groups. The latter compounds were observed at higher fields, close to the signals of the Pt-unsubstituted pyridine compound. These results were explained in terms of the solvent effect. The chemical shifts δ(C) and the coupling constants J(13C–195Pt) were measured and the results interpreted with a view of obtaining information on the nature of the Pt—N bond. The possibility of π-bonding between platinum and the pyridine ligand is examined. The conformation of the pyridine ring in relation to the platinum plane and the energies of the rotation barriers around the Pt—N bond in these types of platinum(II) complexes are briefly discussed. The crystal structure of trans-Pt(2,6-(HOCH2)2py)2Cl2•2H2O was determined by X-ray diffraction. The compound is monoclinic, C2/m, a = 7.022(6), b = 15.646(13), c = 8.344(10) Å, β = 93.35(8)°, Z = 2, R = 0.037. The platinum atom is located at the junction of the twofold axis and the mirror plane, the N atoms and the para-C atom of the pyridine ring are situated on the twofold axis, and the chloride ligands are on the mirror plane. The compound crystallizes with molecules of water, which are H-bonded to the hydroxy groups. The Pt—Cl bond distance is 2.306(2) Å, and that of the Pt—N bond is 2.041 (6) Å. The dihedral angle between the platinum and the pyridine planes is 79.8°. Key words: platinum, pyridine derivatives, NMR, crystal structure.


1985 ◽  
Vol 40 (1) ◽  
pp. 13-18 ◽  
Author(s):  
Kay Jansen ◽  
Kurt Dehnicke ◽  
Dieter Fenske

The syntheses and IR spectra of the complexes [Mo2(O2C-Ph)4X2]2⊖ with X = N3, CI, Br and the counter ion PPh4⊕ are reported. The azido and the bromo complexes are obtained from a solution of [Mo2(O2CPh)4] with PPh4N3 in pyridine or by reaction with PPh4Br in CH2Br2, respectively. When (PPh4)2[Mo2(O2CPh)4(N3)2] is dissolved in CH2Cl2, nitrogen is evolved and the complex with X = CI is obtained. The crystal structure of (PPh4)2[Mo2(O2CPh)4Cl2] · 2CH2Cl2 was determined from X-ray diffraction data (5676 observed independent reflexions, R = 0.042). It crystallizes in the monoclinic space group P21/n with four formula units per unit cell; the lattice constants are a = 1549, b = 1400, c = 1648 pm, β = 94.6°. The centrosymmetric [Mo2(O2CPh)4Cl2]2⊖ ion has a rather short Mo-Mo bond of 213 pm, whereas the MoCl bonds are very long (288 pm)


1983 ◽  
Vol 38 (11) ◽  
pp. 1441-1445 ◽  
Author(s):  
Bernhard Lippert ◽  
Helmut Schöllhorn ◽  
Ulf Thewalt

Oxidation of the head-tail dimer cis-[(NH3)2Pt(1-MeU)]2(NO3)2 (1-MeU = 1-methyl - uracilato anion, C5H5N2O2) with a mixture of nitrous and nitric acid yields three crystalline species, [(NO2)(NH3)2Pt(C5H5N2O2)2Pt(]SrH3)2(NO2)](NO3)2 · 3 H2O (1), [(H2O)(NH3)2Pt(C5H5N2O2)2Pt(]SrH3)2(NO2)](NO3)2 · 5 H2O (2) and [(NO3)(NH3)2Pt(C5H5N2O2)2Pt(]SrH3)2(NO3)](NO3)2 · 4.5 H2O (3). The crystal structure of 2 has been determined. 2 crystallizes in the triclinic space group P1̄ with cell dimensions a= 11.959(4), b= 11.560(3), c= 11.261(2) Å, α = 89.16(2), β= 104.36(2), γ = 99.61(2)° and Z = 2. The structure was refined to R = 0.056, Rw = 0.061 on 4311 reflections. The Pt-Pt distance within the dinuclear cation of 2 is 2.574(1) Å and cor­responds to a Pt-Pt single bond. The axial ligands are N̲O2 (Ptl) and O̲H2 (Pt2), the equatorial ligands two NH3 groups, N 3 and O4 of 1-MeU for both Pt atoms. The oxidation state of Pt in 2 is +III. 1H NMR and IR spectra of 1, 2, and 3 reveal a close structural similarity of the three compounds.


2019 ◽  
Vol 21 (18) ◽  
pp. 9433-9440 ◽  
Author(s):  
Rafael Escribano ◽  
Pedro C. Gómez ◽  
Belén Maté ◽  
Germán Molpeceres ◽  
Emilio Artacho

Use of ab initio molecular dynamics to predict the near-IR spectra of ices and application to astronomical models.


1980 ◽  
Vol 35 (5) ◽  
pp. 522-525 ◽  
Author(s):  
Gisela Beindorf ◽  
Joachim Strähle ◽  
Wolfgang Liebelt ◽  
Kurt Dehnicke

The complexes AsPh4[Cl4V = N-Cl] and AsPh4[VOCl4] are prepared by the reaction of AsPh4Cl with Cl3VNCl and VOCl3, respectively. The IR spectra indicate C4v symmetry for the complex anions with multiple VN and VO bonds and a linear arrangement for the VNCl-group. AsPh4[VOCl4] crystallizes in the tetragonal space group P4/n with two formula units in the unit cell. The crystal structure was solved by X-ray diffraction methods (R = 0,062, 1096 observed, independent reflexions). The structure consists of AsPh4+ cations and [VOCl4]- anions with symmetry C4v. The extremely short VO bond length corresponds with a VO triple; its steric requirements cause the relatively large bond angle OVCl of 103.4°.


2003 ◽  
Vol 405 (2) ◽  
pp. 531-550 ◽  
Author(s):  
M. Schultheis ◽  
A. Lançon ◽  
A. Omont ◽  
F. Schuller ◽  
D. K. Ojha
Keyword(s):  

1985 ◽  
Vol 40 (12) ◽  
pp. 1631-1637 ◽  
Author(s):  
Ruth Christophersen ◽  
Paul Klingelhöfer ◽  
Ulrich Müller ◽  
Kurt Dehnicke

Abstract The pyridine complexes of cyclo-thiazeno vanadium dichloride, [VCl2(N3S2)py] and [VCl2(N3S2)(py)2] were synthesized by reactions of polymeric VCl2(N3S2) with varying amounts of pyridine in CH2Cl2. The compounds were characterized by their IR spectra as well as by their 51V NM R spectra. The crystal structure of [VCl2(N3S2)(C5H5N)] was determined by means of X-ray diffraction (1582 independent observed reflexions, R = 0.031). Crystal data: orthorhombic, space group Pnma, a = 1372, b - 2261, c - 1068 pm, Z = 12. In the lattice there are two monomeric, crystallographically independent molecules [VCl2(N3S2)(C5H5N)], which differ only slightly. The vanadium atoms have a trigonal bipyramidal coordination with the N atom of the pyridine molecule and one chlorine atom in apical positions, and with one chlorine atom and the N atoms of the cyclo-thiazeno ligand in equatorial positions. The VN bond lengths of the planar VN3S2 ring of 174 pm correspond to double bonds


1988 ◽  
Vol 43 (10) ◽  
pp. 1279-1284 ◽  
Author(s):  
Mervat El Essawi ◽  
H Gosmann ◽  
D Fenske ◽  
F Schmock ◽  
K Dehnicke

Triphenylmethylphosphonium nitrite and formate have been prepared by the reaction of [PPh3Me]I with silver nitrite, and lead formate, respectively, in aqueous solutions. [PPh3Me]NO2 (1) forms pale yellow crystals, and [PPh3Me]HCO2·H2O (2) forms white crystals. Both compounds are soluble in water, ethanol, and dichloromethane. In moist air 2 is hydrated to yield [PPh3Me]HCO2·2H2O (3). The compounds were characterized by their IR spectra, 1 and 2 also by X-ray crystal structure determinations.[PPh3Me]NO2 (1): space group P21/n, Z = 4, 2088 independent observed reflexions, R = 0.062. Lattice dimensions (20 °C): a = 914.7(3), b = 1887.5(9), c = 1080.0(4) pm, β = 110.29(3)°. The compound consists of PPh3Me+ ions and NO2- anions with bond lengths of 114.2(6) pm and a bond angle of 124.1(7)°. [PPh3Me]HCO2·H2O (2): space group P21/n, Z = 4, 2973 independent observed reflexions, R = 0.069. Lattice dimensions (-20 °C): a = 931(2), b = 1558(3), c = 1281(2) pm, β = 105.9(1)°. The compound consists of PPh3Me+ ions and formate anions which form centrosymmetric dimeric units [HCO2·H2O]22- through hydrogen bridges of the water molecules. Bond lengths CO 122.4(4) and 120.9(4) pm. bond angle OCO 129.9(4)°.


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