Manganese, molybdenum, and tungsten carbonyl derivatives incorporating the dimethylbis(1-pyrazolyl)gallate ligand, [Me2Ga(N2C3H3)2]−

1981 ◽  
Vol 59 (22) ◽  
pp. 3123-3135 ◽  
Author(s):  
Sharon E. Anslow ◽  
Kenneth S. Chong ◽  
Steven J. Rettig ◽  
Alan Storr ◽  
James Trotter
Keyword(s):  
Mirror Symmetry ◽  
Variable Temperature ◽  
Nmr Studies ◽  
Space Group ◽  
H Nmr ◽  
Carbonyl Derivatives ◽  
Distorted Octahedral Coordination Geometry ◽  
Distorted Octahedral ◽  
Tungsten Carbonyl ◽  
And Tungsten

The synthesis of a number of six-coordinate manganese, molybdenum, and tungsten carbonyl compounds incorporating both the bidentate bispyrazolyl gallate ligand, [Me2Ga(N2C3H3)2]−, and a neutral pyrazole ligand in a facial coordination arrangement are described. Variable temperature 1H nmr studies have revealed interestingly different behaviours in solution for the valence isoelectronic species [Me2Ga(N2C3H3)2](N2C3H4)Mn(CO)3 and [Me2Ga(N2C3H3)2](N2C3H4)Mo(CO)3−. X-ray structural analyses of crystalline samples of the two compounds have been carried out in an effort to shed light on these behavioural differences. Crystals of [Me2Ga(N2C3H3)2](N2C3H4)Mn(CO)3 are monoclinic, a = 31.053(2), b = 8.0503(4), c = 15.8629(8) Å, β = 108.164(2)°, Z = 8, space group C2/c and crystals of [(C2H5)4N]+{[Me2Ga(N2C3H3)2](N2C3H4)Mo(CO)3}− are monoclinic, a = 10.058(1), b = 20.6488(5), c = 13.533(1) Å, β = 93.800(5)°, Z = 4, space group P21/n. Both structures were solved by Patterson and Fourier syntheses and were refined by full-matrix least-squares procedures to final R values of 0.028 and 0.023 for 2613 and 4388 observed reflections for the Mn and Mo complexes, respectively. The neutral Mn complex and the complex Mo anion both have approximate mirror symmetry and both metal atoms have trigonally distorted octahedral coordination geometry. Important bond distances (corrected for thermal vibration) are: Mn—N, 2.074(3)–2.086(3), Mn—C, 1.795(4)–1.809(5), Mo—N, 2.291(2)–2.295(2), and Mo—C, 1.918(3)–1.936(3) Å. Although structural differences between these two species do offer plausible explanations for the differences observed in solution, it appears that other factors are more important.

Lewis acidic titanium species: the synthesis, structure, bonding and molecular modelling considerations of the complexes Ti(NR2)3Cl (R = Me, Et)

1991 ◽  
Vol 69 (2) ◽  
pp. 357-362 ◽  
Author(s):  
David G. Dick ◽  
Roger Rousseau ◽  
Douglas W. Stephan
Keyword(s):  
Molecular Modelling ◽  
Energy Minimization ◽  
Variable Temperature ◽  
Structural Data ◽  
Steric Effects ◽  
Monoclinic Space Group ◽  
Nmr Studies ◽  
Space Group ◽  
H Nmr ◽  
Multiple Bonding

Reaction of simple amides with TiCl4 affords mixed amido-chloride species Ti(NR2)4−nCln. The trisamide-chloride species Ti(NR2)3Cl can be prepared directly employing three equivalents of amide or by reaction Ti(NR2)4 with TiCl4. The compound Ti(NMe2)3Cl, 1, crystallizes in the trigonal space group [Formula: see text] with a = 11.525(5), c = 14.939(3) Å, Z = 6, and V = 1718(1) Å3. The compound Ti(NEt2)3Cl, 2, crystallizes in the monoclinic space group P21/c, with a = 8.385(2) Å, b = 15.958(2) Å, c = 14.230(4) Å, β = 107.79(1)°, Z = 4, and V = 1813(1) Å3. The geometry of the Ti coordination sphere in these complexes is best described as pseudo-tetrahedral. The structural data are consistent with Ti—N multiple bonding. Preliminary results of EHMO calculations are consistent with dπ—pπ Ti—N bonding. Attempts to replace the halides with phosphides (LiPR2, R = Me, Et, Ph) led not to the Ti(IV) phosphido species, but rather to redox chemistry yielding Ti(III) amides and P2R4. The barrier to rotation about the Ti—N bonds has been considered. Variable temperature 1H NMR studies reveal that the barrier is small. Extended Hückel total energy minimization calculations have been performed. In addition, MMX calculations of the barrier to Ti—N rotation are reported. The results of these calculations imply that the rotational barrier is dominated by steric effects. Key words: titanium amides, structures, Ti—N bonding

Thiophenophane metal complexes. II. Preparation, structure, and properties of binuclear copper(II) complexes and of 2,5,9,12-tetrathia[13](2,5) thiophenophane. Evidence for S-coordinated thiophene

1989 ◽  
Vol 67 (4) ◽  
pp. 639-647 ◽  
Author(s):  
C. Robert Lucas ◽  
Shuang Liu ◽  
Michael J. Newlands ◽  
Jean-Pierre Charland ◽  
Eric J. Gabe
Keyword(s):  
Electronic Spectra ◽  
Molecular Structures ◽  
Structure And Properties ◽  
Binuclear Copper ◽  
Space Group ◽  
H Nmr ◽  
Trigonal Bipyramidal ◽  
Distorted Octahedral Coordination Geometry ◽  
Distorted Octahedral ◽  
Group A

Preparations of the thiophenophane C13H20S5, (L2), its binuclear copper(II) complex, (CuCl2•L2)2 and the related thiophenophane complex (CuCl2•L1)2 (L1 = C10H14S4) are described. The 13C and 1H nmr spectra of L2 and the ir and electronic spectra of the complexes are reported. The molecular structures of L2, (CuCl2•L1)2, and (CuCl2•L2)2 have been determined. For L2: space groupP21/a,a = 14.658(1), b = 5.9800(3), c = 19.772(2) Å, β = 111.00(1)°, Z = 4, Rf = 0.050,Rw = 0.046. For (CuCl2•L1)2: space group Pbca, a = 15.383(6), b = 11.409(3), c = 17.423(4) Å, Z = 4, Rf = 0.057, Rw = 0.036. For (CuCl2•L2)2: space group A2/a, a = 12.616(1), b = 10.0542(6), c = 29.180(2) Å, β = 95.81(1)°, Z = 4, Rf = 0.055, Rw = 0.038. The complex (CuCl2•L1)2 has distorted octahedral coordination geometry about each copper. The copper atoms are linked by two bridging chlorines and each copper also bears one terminal chlorine, two thioether-sulfurs and a thiophene-sulfur. In contrast, (CuCl2•L2)2 does not involve coordination by thiophene-sulfur and the remaining coordination sphere has undergone distortion from square pyramidal towards trigonal bipyramidal. Differences in the electronic spectra are interpreted in terms of the structures of the complexes. Keywords: binuclear copper(II) thiophenophane complex.

Chiral "basket handle" binaphthyl porphyrins: synthesis, catalytic epoxidation and NMR conformational studies

2010 ◽  
Vol 14 (07) ◽  
pp. 646-659 ◽  
Author(s):  
Eric Rose ◽  
Emma Gallo ◽  
Nicolas Raoul ◽  
Léa Bouché ◽  
Ariane Pille ◽  
...  
Keyword(s):  
Time Scale ◽  
Room Temperature ◽  
Conformational Equilibrium ◽  
Variable Temperature ◽  
Conformational Exchange ◽  
Iron Catalysts ◽  
Nmr Studies ◽  
Conformational Studies ◽  
H Nmr ◽  
Catalytic Epoxidation

Three "basket handle" porphyrins have been prepared by condensation of tetrakis-(α,β,α,β-2-aminophenyl)porphyrin atropoisomer with 1,1′-binaphthyl, 2,2′-dimethoxy, -3,3′-dicarbonylchloride, -3,3′-diacetylchloride and -3,3′-dipropanoylchloride. The epoxidation of styrene with the three iron catalysts, obtained after metalation of the free porphyrins, occurs with good yields and moderate ee up to 54%. These porphyrins showed unexpected conformational differences, as revealed by NMR spectroscopy. In particular, variable temperature NMR studies showed that the methoxy group in one of them undergoes intermediate conformational exchange on the 1H NMR time scale at room temperature. Lowering the temperature to -50 °C revealed the presence of four states in slow exchange on the NMR time scale. These results evidence a dynamic conformational equilibrium of the binaphthyl handles that adopt different, asymmetric positions with respect to the porphyrin plane.

Calcium-bis[N,N'-bis(trimethylsilyl)benzamidinat]-THF (1/2) - Synthese, spektroskopische Charakterisierung und Struktur/Calcium-bis[N,N'-bis(trimethylsilyl)benzamidinate]-THF (1/2) - Syntheses, Spectroscopic Characterization and Structure

1992 ◽  
Vol 47 (4) ◽  
pp. 453-459 ◽  
Author(s):  
Matthias Westerhausen ◽  
Wolfgang Schwarz
Keyword(s):  
Title Compound ◽  
High Field ◽  
Spectroscopic Characterization ◽  
Calcium Atom ◽  
Space Group ◽  
Bond Lengths ◽  
H Nmr ◽  
Distorted Octahedral ◽  
Anionic Charge ◽  
Field Shift

The reaction of calcium-bis[bis(trimethylsilyl)amide]-THF (1/2) with benzonitrile in THF nearly quantitatively yields the title compound calcium-bis[N,N'-bis(trimethylsilyl)- benzamidinate]-THF (1/2). Under similar conditions pivalonitrile substitutes an ether ligand of calcium-bis[bis(trimethylsilyl)amide]-DME (1/2) without the formation of the corresponding amidinate derivative. The calcium-di(benzamidinate) [H5C6-C(NSiMe3)2]2Ca · 2THF crystallizes in the space group Pbcn with {a = 188.8(6); b = 1286.0(3); c = 1802.5(5) pm; Z = 4}. The calcium atom is hexa-coordinate with a distorted octahedral trans-configuration and with Ca - O and Ca - N bond distances of 238 and 243 pm, respectively. The bond lengths within the NCN moiety with values of 132 pm are characteristic of a diazaallylic system. The short N - Si bond lengths of about 170.5 pm as well as the high field shift of the 29Si{1H} NMR signal are evidence for an effective backdonation of the anionic charge from the nitrogen to the silicon atoms.

Chromium, molybdenum and tungsten carbonyl derivatives of distibinomethane ligands †

1998 ◽  
pp. 825-832 ◽  
Author(s):  
Angela M. Hill ◽  
Nicholas J. Holmes ◽  
Anthony R. J. Genge ◽  
William Levason ◽  
Michael Webster ◽  
...  
Keyword(s):  
Carbonyl Derivatives ◽  
Tungsten Carbonyl ◽  
Derivatives Of ◽  
And Tungsten

Rhodium(I) complexes containing bidentate pyrazolylgallate ligands. X-ray crystal structures of [Me2Gapz2]Rh(COD), [Rh(μ-3,5-Me2pz)(CO)2]2, and [Rh(μ-3,5-Me2pz)(COD)]2

1984 ◽  
Vol 62 (6) ◽  
pp. 1057-1067 ◽  
Author(s):  
Brenda M. Louie ◽  
Steven J. Rettig ◽  
Alan Storr ◽  
James Trotter
Keyword(s):  
Solid State ◽  
Structural Parameters ◽  
Heavy Atom ◽  
Boat Conformation ◽  
Nmr Studies ◽  
Space Group ◽  
H Nmr ◽  
Square Planar ◽  
Dirhodium Complexes

The synthesis and characterization of the complexes [Me2Gapz2]Rh(LL) (where LL = COD, (CO)2, (PPh3)2, or (PPh3)(CO)), incorporating the bidentate, chelating, dimethylbis(1-pyrazolyl)gallate ligand are described. Non-rigidity in solution has been demonstrated by 1H nmr studies for some of the complexes. A crystal structure determination of the COD complex has confirmed the boat conformation for the Ga—(N—N)2—Rh six-membered ring in this complex in the solid state. In addition, the solid state structures of the 3,5-dimethylpyrazolyl bridged dirhodium complexes [Rh(μ-3,5-Me2pz)(CO)2]2 and [Rh(μ-3,5-Me2pz)(COD)]2 have been determined. Crystals of [Me2Gapz2]Rh(COD) are orthorhombic, a = 22.7447(8), b = 11.9776(5), c = 6.4635(3) Å, Z = 4, space group Pnma; those of [Rh(μ-3,5-Me2pz)(CO)2]2 are monoclinic, a = 8.7403(6), b = 16.3594(6), c = 25.434(2) Å, β = 95.286(3)°, Z = 8, space group P21/c; and those of [Rh(μ-3,5-Me2pz)(COD)]2 are triclinic, a = 10.350(2), b = 11.401(2), c = 12.355(2) Å, α = 112.485(7), β = 99.394(9), γ = 105.387(8)°, Z = 2, space group [Formula: see text]. All three structures were solved by conventional heavy atom techniques and were refined by full-matrix least-squares procedures to final conventional R values of 0.026, 0.024, and 0.037 for 1824, 5135, and 6109 reflections with I ≥ 3σ(I), respectively. In each case the Rh atoms have distorted square planar coordination geometry. Important mean structural parameters are Rh—N = 2.087(2), Rh—C = 2.129(2), [Formula: see text] for [Me2Gapz2]Rh(COD); Rh—N = 2.063(6), Rh—CO = 1.852(9), [Formula: see text] for [Rh(μ-3,5-Me2pz)(CO)2]2; and Rh—N = 2.084(1), Rh—C = 2.131(7), [Formula: see text] for [Rh(μ-3,5-Me2pz)(COD)]2.

Multinuclear NMR studies of molybdenum and tungsten carbonyl isocyanide complexes

1989 ◽  
Vol 28 (15) ◽  
pp. 2954-2958 ◽  
Author(s):  
Martin Minelli ◽  
Walter J. Maley
Keyword(s):  
Nmr Studies ◽  
Multinuclear Nmr ◽  
Tungsten Carbonyl ◽  
And Tungsten

Structural studies of organoboron compounds. XIX. 1,7-Dimethyl-3,5-diphenyl-2,4,6-trioxa-7-aza-1-azonia-3-bora-5-boratabicyclo[3.3.0]octane

1984 ◽  
Vol 62 (3) ◽  
pp. 515-520 ◽  
Author(s):  
Wolfgang Kliegel ◽  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Solid State ◽  
Least Squares ◽  
Variable Temperature ◽  
Direct Methods ◽  
Structural Studies ◽  
Organoboron Compounds ◽  
Full Matrix ◽  
Space Group ◽  
H Nmr ◽  
Valence Tautomers

Crystals of 1,7-dimethyl-3,5-diphenyl-2,4,6-trioxa-7-aza-1-azonia-3-bora-5-boratabicyclo[3.3.0]octane are triclinic, a = 10.559(2), b = 15.156(3), c = 10.338(2) Å, α = 99.14(1), β = 89.90(1), γ = 96.73(1)°, Z = 4, space group [Formula: see text]. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to R = 0.032 and Rw = 0.038 for 2396 reflections with I ≥ 3σ(I). The structure consists of two crystallographically independent, but virtually identical, molecules containing sterically lengthened N—B coordinative bonds (mean 1.740(3) Å). The structurally inequivalent (in the solid state) pairs of N-methyl and B-phenyl groups are observed by variable temperature 1H nmr to be magnetically equivalent in solution, implying a rapid interconversion of "valence tautomers" at temperatures down to −60 °C.

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