A weakly coordinating anion as a tripodal “Br3”-ligand for platinum(IV) — Structure of [(closo-CB11H6Br6)PtMe3]

2009 ◽  
Vol 87 (1) ◽  
pp. 95-102 ◽  
Author(s):  
Antonio G De Crisci ◽  
Jesse Kleingardner ◽  
Alan J Lough ◽  
Anna Larsen ◽  
Ulrich Fekl
Keyword(s):  
Nmr Spectroscopy ◽  
Spectroscopic Data ◽  
Octahedral Geometry ◽  
Metal Center ◽  
Methyl Groups ◽  
Coupling Constant ◽  
Bond Lengths ◽  
Trans Influence ◽  
Lower Hemisphere ◽  
Weakly Coordinating

Synthesis, structure, and NMR spectroscopic data for [(closo-CB11H6Br6)PtMe3] are reported. This neutral platinum(IV) complex contains the closo-CB11H6Br6– anion bonded to the trimethylplatinum(IV) cation via three boron-bound bromines. Closo-CB11H6Br6–, which often acts as weakly coordinating or even non-coordinating anion, adopts here a role still very rare for this anion: it acts as a tripodal capping ligand enabling a pseudo-octahedral geometry at a d6 metal center. Three bromines from the lower hemisphere of the hexahalogenated carboranate coordinate to Pt(IV), and distortions from ideal octahedral angles at Pt are marginal (<3°). Pt-Br bond lengths are 2.7279(18), 2.7129(17), and 2.7671(18) Å. Using the 2JPtH coupling constant of Pt-bonded methyl groups (79.0 Hz) as indicator of the donor strength of the tripodal cap, the prediction is obtained that closo-CB11H6Br6– is a relatively weak donor toward the trimethylplatinum(IV) cation. Ligand competition equilibria can be expected to depend on both the intrinsic donor strengths of competing ligands and on the effects of charge and geometry. We observe that closo-CB11H6Br6– is capable of replacing acetone from Me3Pt(acetone)3+, whereas BF4– counterion is unable to replace acetone under similar conditions.Key words: non-coordinating anion, platinum(IV), trimethyl, closo-carboranate, tripodal, trans-influence, NMR spectroscopy.

Dichlorido(N,N′-dibenzylideneethane-1,2-diamine-κ2 N,N′)[(2,2-dimethyl-1,3-dioxolane-4,5-diyl)bis(diphenylmethanolato)-κ2 O,O′]titanium(IV)

2007 ◽  
Vol 63 (11) ◽  
pp. m2842-m2843 ◽  
Author(s):  
Chien-An Chen ◽  
Liang-Ying Chiang ◽  
Han-Mou Gau
Keyword(s):  
Molecular Structure ◽  
Title Compound ◽  
Chloride Ions ◽  
Octahedral Geometry ◽  
Metal Center ◽  
Distorted Octahedral Geometry ◽  
Titanium Metal ◽  
Bond Lengths ◽  
Distorted Octahedral ◽  
Chloride Ligands

The title compound, [TiCl2(C31H28O4)(C16H16N2)], is a titanium(IV) complex of the bidentate 2,2-dimethyl-α,α,α′,α′-tetraphenyl-1,3-dioxolane-4,5-dimethanolate (TADDOLate) ligand containing also two chloride ions and a bidentate neutral N,N′-dibenzylideneethane-1,2-diamine ligand. The molecular structure has a distorted octahedral geometry around the titanium metal center. The Ti—N bond lengths of 2.246 (2) and 2.2476 (17) Å are long, indicating weak bonding between the titanium(IV) metal center and the imine N atoms. Though the two chloride ligands are trans to each other, they bend away from the Ti–TADDOLate bonds with a Cl—Ti—Cl angle of 163.96 (3)°.

1H and 13C nuclear magnetic resonance assignment of fluorescent olefinic sterol derivatives for use as membrane probes

1987 ◽  
Vol 65 (8) ◽  
pp. 1784-1794 ◽  
Author(s):  
Jacinta Drew ◽  
Jean-Robert Brisson ◽  
Peter Morand ◽  
Arthur G. Szabo
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Chemical Shifts ◽  
Methyl Groups ◽  
Coupling Constant ◽  
13C Nuclear Magnetic Resonance ◽  
High Degree ◽  
Degree Of Similarity ◽  
C Nmr ◽  
Membrane Probes

A number of fluorescent steroids with unsaturated sidechains have been analyzed by high resolution 1H and 13C nmr spectroscopy. The geometry of the olefinic systems was assigned on the basis of 1H–1H shift-correlated spectra (COSY) and selected nOe difference experiments. For one of these compounds, a 13C–1H shift-correlated spectrum, a COSY spectrum, a 1H J-resolved spectrum as well as nOe experiments on the angular methyl groups permitted complete ring proton assignment and coupling constant analysis. The high degree of similarity of the ring carbon 13C chemical shifts of these steroids and cholesterol would indicate that the former have the potential for use as fluorescent probes of cholesterol domains in membranes.

Structure cristalline et moléculaire du cis-dithiocyanatobis(phénanthroline-1,10)mercure(II), Hg(SCN)2(C12H8N2)2

1974 ◽  
Vol 52 (16) ◽  
pp. 2923-2927 ◽  
Author(s):  
André L. Beauchamp ◽  
Bernard Saperas ◽  
Roland Rivest
Keyword(s):  
Heavy Atom ◽  
Octahedral Geometry ◽  
Van Der Waals Interactions ◽  
Distorted Octahedral Geometry ◽  
Triclinic Space Group ◽  
Bond Lengths ◽  
R Factor ◽  
Distorted Octahedral ◽  
Phenanthroline Ligands ◽  
Heavy Atom Method

The compound cis-Hg(SCN)2(Phen)2 belongs to the triclinic space group [Formula: see text] with a = 13.252(5), b = 11.077(4), c = 8.443(3) Å, α = 105.20(3), β = 83.25 (3), γ = 90.92(3)°, and Z = 2. The structure was solved by the heavy atom method and refined on 1718 independent reflections to an R factor of 0.069. The crystal contains discrete molecules, in which mercury is coordinated to four nitrogen atoms from two phenanthroline molecules and to two sulfur atoms from thiocyanate groups. These donor atoms define a distorted octahedral geometry around mercury. The Hg—N bond lengths are in the range 2.42(2)–2.52(2) Å, whereas the Hg—S bonds are equal to 2.622(8) and 2.582(8) Å. The molecules are packed in layers parallel to the (110) planes and the layers are held together by normal van der Waals interactions. Within the layers, the packing of the complex is characterized by parallel stacking of phenanthroline ligands at distances of ∼3.4 Å. The terminal nitrogen atoms of the thiocyanate groups are uncoordinated.

Nuclear magnetic resonance studies on the anions [M(SnCl3)5Cl]4− (M = Ru, Os) and [Ru(SnCl3)5(MeCN)]3−: the X-ray crystal structure of [N(C2H5)4]4[Ru(SnCl3)5Cl]

1982 ◽  
Vol 60 (11) ◽  
pp. 1304-1316 ◽  
Author(s):  
Louis J. Farrugia ◽  
Brian R. James ◽  
Claude R. Lassigne ◽  
Edward J. Wells
Keyword(s):  
Crystal Structure ◽  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Octahedral Geometry ◽  
Coupling Constants ◽  
Order Effects ◽  
Magnetic Resonance Studies ◽  
X Ray ◽  
Crystallographic Study

The octahedral anions [M(SnCl3)5Cl]4− (M = Ru, Os) have been fully characterized by 119Sn FT nmr spectroscopy. For M = Ru, 117Sn and 115Sn nmr spectra were also recorded, and an X-ray crystallographic study was carried out on the tetraethylammonium salt, isolated as a disolvate from acetonitrile. The Ru—Sn bond lengths indicate some degree of dπ–dπ interactions. The slight distortions from octahedral geometry are discussed in connection with the packing of the chlorine atoms. The Sn nmr spectra reveal the first observed coupling to a 99Ru nucleus (I = 5/2, 12.7% natural abundance), very large 2J(119Sn—117Sn) coupling constants, and the first observed second-order effects on a heteronuclear system. The octahedral anion [Ru(SnCl3)5(MeCN)]3− was also synthesized as the tetraethylammonium salt and characterized spectroscopically.

scholarly journals Crystal structure ofN′′-benzyl-N′′-[3-(benzyldimethylazaniumyl)propyl]-N,N,N′,N′-tetramethylguanidinium bis(tetraphenylborate)

2015 ◽  
Vol 71 (12) ◽  
pp. o1086-o1087
Author(s):  
Ioannis Tiritiris ◽  
Willi Kantlehner
Keyword(s):  
Crystal Structure ◽  
Double Bond ◽  
Positive Charge ◽  
Planar Geometry ◽  
Methyl Groups ◽  
Two Dimensional ◽  
Single Bond ◽  
Double Bond Character ◽  
Bond Lengths ◽  
Bond Character

In the crystal structure of the title salt, C24H38N42+·2C24H20B−, the C—N bond lengths in the central CN3unit of the guanidinium ion are 1.3364 (13), 1.3407 (13) and 1.3539 (13) Å, indicating partial double-bond character. The central C atom is bonded to the three N atoms in a nearly ideal trigonal–planar geometry and the positive charge is delocalized in the CN3plane. The bonds between the N atoms and the terminal methyl groups of the guanidinium moiety and the four C—N bonds to the central N atom of the (benzyldimethylazaniumyl)propyl group have single-bond character. In the crystal, C—H...π interactions between the guanidinium H atoms and the phenyl C atoms of the tetraphenylborate ions are present, leading to the formation of a two-dimensional supramolecular pattern parallel to theacplane.

scholarly journals Germacranolide Rich Essential Oil from Neolitsea pallens

2007 ◽  
Vol 2 (5) ◽  
pp. 1934578X0700200 ◽  
Author(s):  
Rajendra C. Padalia ◽  
Chandan S. Chanotiya ◽  
Bhawani C. Thakuri ◽  
Chandra S. Mathela
Keyword(s):  
Nmr Spectroscopy ◽  
Essential Oil ◽  
Spectroscopic Data ◽  
Volatile Constituents ◽  
Commercial Importance ◽  
Germacrene D ◽  
Leaf Oil ◽  
Fruit Oil

The composition of the steam volatile constituents of leaf, fruit and bark of Neolitsea pallens (D. Don) syn. Litsea umbrosa var. consimilis Nees Hook f. syn. L. consimilis Nees were analyzed by GC, GC-MS and NMR spectroscopy. The major constituents of the leaf oil were furanogermenone (30.6%), β-caryophyllene (19.3%) and germacrene D (12.7%), while oxygenated sesquiterpenoids (83.6%) constitute the major proportion of the bark oil, which is dominated by furanogermenone (59.1%), germacrone (9.3%), 10- epi-γ-eudesmol (7.8%) and curcumenol (5.3%). The fruit oil was mainly composed of furanogermenone (54.8%), trans-β-ocimene (8.8%), sabinene (6.4%) and germacrene D (4.0%). The major constituents were isolated and characterized on the basis of NMR spectroscopic data. The furano sesquiterpenoids, the major constituents of N. pallens, are of chemosystematic and commercial importance.

scholarly journals Crystal structure of the coordination compound of triiodidomethyltin(IV) with 2,2′-bipyridine, MeSnI3·bipy

2016 ◽  
Vol 72 (1) ◽  
pp. 17-20
Author(s):  
Hans Reuter ◽  
Martin Reichelt
Keyword(s):  
Chelate Ring ◽  
Octahedral Geometry ◽  
Distorted Octahedral Geometry ◽  
Orthorhombic Space Group ◽  
Methyl Group ◽  
Bond Lengths ◽  
Distorted Octahedral ◽  
Bipyridine Ligand ◽  
Twisting Angle ◽  
Van Der Waals Contacts

The title compound, (2,2′-bipyridine-κ2N,N′)triiodidomethyltin(IV), [Sn(CH3)I3(C10H8N2)], crystallizing in the non-centrosymmetric orthorhombic space groupPca21as an inversion twin, represents one of the few structurally characterized coordination compounds of an organotin(IV) trihalide with 2,2′-biypridine. Its distorted octahedral geometry shows a meridional arrangement of the I atoms and the methyl group is in-plane with the five-membered chelate ring. Asymmetric bonding of the biypridine ligand to the tin(IV) atom is reflected by different Sn—N bond lengths [2.268 (4) Åversus2.293 (4) Å] and caused by the statictranseffect of the methyl group. Sn—I bond lengths show some differences with respect to their orientation to the methyl group or the bipyridine ligand, respectively. Angular distortions in the coordination sphere of the SnIVatom mainly arise from the large I atoms. Distortion of the 2,2′-bipyridine ligand as a result of its coordination to the SnIVatom are described by the twisting angle of 2.5 (2)° between the least-squares planes of the two pyridine rings, as well as by the angle of 6.2 (2)° between the two lines through the pyridine-connecting C atoms and thepara-orientated C atoms. Directional intermolecular interactions are restricted to weak I...H van der Waals contacts.

scholarly journals A quantum mechanical alternative to the Arrhenius equation in the interpretation of proton spin–lattice relaxation data for the methyl groups in solids

2015 ◽  
Vol 17 (43) ◽  
pp. 28866-28878 ◽  
Author(s):  
Piotr Bernatowicz ◽  
Aleksander Shkurenko ◽  
Agnieszka Osior ◽  
Bohdan Kamieński ◽  
Sławomir Szymański
Keyword(s):  
Nmr Spectroscopy ◽  
Arrhenius Equation ◽  
Lattice Relaxation ◽  
Proton Spin ◽  
Spin Lattice Relaxation ◽  
Quantum Mechanical ◽  
Methyl Groups ◽  
Relaxation Data ◽  
Spin Lattice ◽  
Nuclear Spin Lattice Relaxation

The issue of nuclear spin–lattice relaxation in methyl groups in solids has been a recurring problem in NMR spectroscopy.

Berechnung der 19F- und 195 Pt-NMR-Verschiebungen von FIuoro-Chloro-Bromo-Platinaten(IV) / Calculation of 19F and 195Pt NMR Shifts of Fluoro-Chloro-Brom o-Platinates(IV )

1997 ◽  
Vol 52 (4) ◽  
pp. 435-442 ◽  
Author(s):  
H.-H. Drews ◽  
W. Preetz
Keyword(s):  
Experimental Data ◽  
Chemical Shifts ◽  
Coupling Constant ◽  
Lower Field ◽  
Trans Influence ◽  
Nmr Signals ◽  
Increments Of Chemical Shifts ◽  
Good Agreement

By reaction of [PtBr4]2- with XeF2 in dichloromethane product mixtures containing nine fluoro-chloro-, four fluoro-bromo- and 15 fluoro-chloro-bromo-platinates(IV) are formed. All complexes are detectable by in situ l9F NMR measurements. Due to the increasing trans influence F < Cl < Br, the signals <5(19F) of symmetric F-Pt-F axes observed at highest field are shifted downfield on the average by 93 ppm as compared with δ(19F•) of F••Pt-Cl′ axes, and further to lower field by 40 ppm for <5(F••) of F••-Pt-Br″ axes. For the same reason the coupling constant 1J(F••Pt) ≈ 1099 Hz is by 13.3 % smaller than 1J(F•Pt) ≈ 1268 Hz, which is by 32.3 % smaller than δ(FPt) ≈ 1873 Hz. Based on the axis method, and taking into account characteristic increments of chemical shifts depending on cis influences, the calculation of the 195Pt NMR signals of 27 observed species of the system [PtFnCl6-n-mBrm]2- n, m = 0 - 6, has been successful. The 195Pt NMR shifts of further 29 so far not detected complexes are predicted. Using parameters depending on the geometry of the complex, the 19F NMR shifts of 28 F-containing platinates(IV) have been calculated in good agreement with the experimental data. 19F resonances are predicted for 19 so far missing complexes.

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