Conjugative interactions in 1-methylpyrrol-2-yl derivatives of the cyclic phosphazenes (NPF2)n (n = 3–6): the crystal and molecular structure of 1-methylpyrrol-2-ylheptafluorocyclotetraphosphazene

1982 ◽  
Vol 60 (4) ◽  
pp. 535-541 ◽  
Author(s):  
Rajendra D. Sharma ◽  
Steven J. Rettig ◽  
Norman L. Paddock ◽  
James Trotter
Keyword(s):  
Intramolecular Charge Transfer ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Mean Value ◽  
Full Matrix ◽  
Geometrical Features ◽  
Electron Release ◽  
The Mean ◽  
Cyclic Phosphazenes ◽  
Derivatives Of

1-Methylpyrroles, in which the 2-position is occupied by a pentafluorocyclotriphosphazenyl (1a), heptafluorocyclotetraphosphazenyl (1b), nonafluorocyclopentaphosphazenyl (1c), or undecafluorocyclohexaphosphazenyl group (1d), have been prepared from 2-lithio-1-methylpyrrole and the corresponding fluorophosphazene. Crystals of 1b are monoclinic, a = 17.300(2), b = 5.0281(3), c = 16.902(2) Å, β = 108.904(4)°, Z = 4, space group P2/n. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to R = 0.038 and Rw = 0.047 for 1167 observed reflections. The N4P4 ring is nearly planar. The P—N bond lengths (corrected for libration) range from 1.524(5) to 1.562(5) Å with a mean value of 1.541(17) Å, and the mean ring angles are 122.9(20)° at phosphorus and 146.4(23)° at nitrogen. The geometry of the 1-methylpyrryl group shows no unexpected features, but the P—C bond (1.756(5) Å) is significantly shorter than in typical P-phenyl derivatives, and the P—F bond at the same atom is comparatively long (1.561(4) Å). Conjugative electron release from the pyrryl group, involving pπ–dπ bonding, is indicated both by these geometrical features and by the appearance of intramolecular charge transfer bands in the electronic spectra of 1(a–d).

Structural studies of organoboron compounds. XXII. Preparation and crystal and molecular structure of tetramethylammonium-2,4,6,6-tetraphenyl-1,3,5-trioxa-2,4- dibora-6-boratacyclohexane

1985 ◽  
Vol 63 (12) ◽  
pp. 3516-3520 ◽  
Author(s):  
W. Kliegel ◽  
H.-W. Motzkus ◽  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Physical Properties ◽  
Crystal And Molecular Structure ◽  
Structural Parameters ◽  
Direct Methods ◽  
Maximum Deviation ◽  
Structural Studies ◽  
Full Matrix ◽  
The Mean

Details of the preparation and physical properties of (Me4N)+ (Ph4B3O3)− are given. Crystals of tetramethylammonium 2,4,6,6-tetraphenyl-1,3,5-trioxa-2,4-dibora-6-boratacyclohexane are orthorhombic, a = 18.130(2), b = 11.9745(7), c = 12.5187(5) Å, Z = 4, space group Pna21. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to R = 0.056 and Rw = 0.064 for 1460 reflections with I ≥ 2σ(I). The crystal structure consists of discrete tetramethylammonium cations and tetraphenylboroxinate anions, the first such anion to be structurally characterized. The six-membered B3O3 ring is significantly non-planar, having a flattened O(1)-envelope conformation (maximum deviation from the mean plane = 0.074(4) Å for O(1)). The boroxine ring in the anion shows significant deviations from the D3h symmetry observed for neutral boroxines. Important mean structural parameters: B(sp3)—O = 1.494(2), B(sp2)—O[B(sp3)] = 1.320(9), B(sp2)—O[B(sp2)] = 1.389(3) Å, O—B(sp3)—O = 110.5(5), O—B(sp2)—O = 121.7(6), B(sp2)—O—B(sp2) = 118.9(5), and B(sp3)—O—B(sp2) = 122.9(1)°.

Crystal and molecular structure of hexadecamethylcyclooctaphosphazene, (NPMe2)8

1977 ◽  
Vol 55 (13) ◽  
pp. 2530-2533 ◽  
Author(s):  
Richard T. Oakley ◽  
Norman L. Paddock ◽  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Molecular Structure ◽  
Least Squares ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Membered Ring ◽  
Weighted Mean ◽  
Full Matrix ◽  
Space Group ◽  
Bond Lengths ◽  
The Mean

Crystals of hexadecamethylcyclooctaphosphazene are tetragonal, a = 13.637(1), c = 8.215(1) Å, Z = 2, space group P4/n. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to a final R of 0.033 and Rw of 0.032 for 1306 reflections with I ≥ 4σ(I) The molecule has crystallographic fourfold (C4) symmetry with weighted mean bond lengths P—N, 1.590(13), P—C, 1.811(2), and C—H, 0.95(2) Å (those not involving hydrogen have been corrected for libration, rms deviations from the mean are given in parentheses). Angles in the 16-membered ring are 119.2(1) and 115.1(1)° at P and 131.5(1) and 148.2(1)° at N.

Crystal and Molecular Structure of Hexakis(dimethylamino)cyclotriphosphazene, [NP(NMe2)2]3

1973 ◽  
Vol 51 (8) ◽  
pp. 1295-1302 ◽  
Author(s):  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Molecular Structure ◽  
Least Squares ◽  
Electron Density ◽  
Title Compound ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Full Matrix ◽  
Space Group ◽  
The Mean

Crystals of the title compound are monoclinic, a = 15.539(4), b = 9.061(1), c = 16.707(6) Å, β = 107.19(5)°, Z = 4, space group P21/c. The measured and calculated densities are 1.19 and 1.180(1) g cm−3, respectively. The structure was determined by direct methods and refined by electron-density and full-matrix least-squares procedures to R = 0.047 for 2503 observed reflections. The six-membered phosphazene ring is slightly, but significantly, non-planar, the conformation being that of a distorted boat. The molecule has approximate D3 symmetry. The ring P—N bonds are all equal, mean P—N = 1.588(3) Å, and the relatively short exocyclic P—N bonds, mean 1.652(4) Å, indicate the presence of exocyclic π-bonding in the molecule. The N—C bonds range from 1.417(7) to 1.471(5) with a mean of 1.45(2) Å. The mean endocyclic N—P—N and P—N—P angles are 116.7(4) and 123.0(4)°, respectively, while the exocyclic N—P—N angles average 101.5(8)°.

N,N-Ethylenebis(salicylideneimine) derivatives of gallium trimethyl: crystal and molecular structure of N,N-ethylenebis(salicylideneiminato) bis(dimethylgallium)

1977 ◽  
Vol 55 (13) ◽  
pp. 2540-2546 ◽  
Author(s):  
Kenneth S. Chong ◽  
Steven J. Rettig ◽  
Alan Storr ◽  
James Trotter
Keyword(s):  
Molecular Structure ◽  
Solid State ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Coordination Geometry ◽  
Tetrahedral Coordination ◽  
Weighted Mean ◽  
Full Matrix ◽  
Derivatives Of ◽  
Distorted Tetrahedral Coordination

Crystals of N,N-ethylenebis(salicylideneiminato)bis(dimethylgallium) are orthorhombic, a = 22.781(1), b = 9.4869(6), c = 19.700(2) Å, Z = 8, space group Pbca. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to a final R of 0.036 and Rw of 0.029 for 2248 reflections with I ≥ 3σ(I). Details of the preparation and physical properties of (C16H14N2O2)(GaMe2)2 and (C16H15N2O2)(GaMe2) are given. The (C16H14N2O2)(GaMe2)2 molecule is approximately centrosymmetric in the solid state. A "GaMe2" unit is coordinated to each of the two salicylideneiminato moieties of the N,N-ethylenebis(salicylideneiminato) ligand. The gallium atoms have a distorted tetrahedral coordination geometry, with bond angles at gallium ranging from 92.7(1) to 124.6(3)°. Important bond lengths (corrected for libration) are: Ga—O, 1.886(2) and 1.884(2), Ga—N, 2.033(3) and 2.042(3), and weighted mean Ga—C, 1.959(9) Å.

Crystal and molecular structure of phenylboronic acid, C6H5B(OH)2

1977 ◽  
Vol 55 (17) ◽  
pp. 3071-3075 ◽  
Author(s):  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Molecular Structure ◽  
Crystal And Molecular Structure ◽  
Phenylboronic Acid ◽  
Direct Methods ◽  
Asymmetric Unit ◽  
Full Matrix ◽  
Dimeric Unit ◽  
Infinite Array ◽  
The Mean ◽  
Independent Molecules

Crystals of phenylboronic acid are orthorhombic, a = 17.9049(7), b = 115.3264(5), c = 9.8113(2) Å, Z = 16, space group Iba2. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to a final R of 0.031 and Rw of 0.041 for 1409 reflections with I ≥ 3σ(I). The asymmetric unit consists of two independent molecules linked by a pair of O—H … O hydrogen bonds. Each dimeric unit is also hydrogen bonded to four other such units (at [Formula: see text]) to form an infinite array of layers which stack along the c axis. Mean bond lengths corrected for libration (rms deviations from the mean in parentheses) are: O—B, 1.371(7), B—C, 1.565(3), and C—C(phenyl), 1.394(11) Å.

The preparation and the crystal and molecular structure of tetradecamethylcycloheptaphosphazene, (NPMe2)7

1977 ◽  
Vol 55 (2) ◽  
pp. 304-309 ◽  
Author(s):  
Keith D. Gallicano ◽  
Richard T. Oakley ◽  
Norman L. Paddock ◽  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Molecular Structure ◽  
Least Squares ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Membered Ring ◽  
Full Matrix ◽  
Space Group ◽  
Bond Lengths ◽  
The Mean

The preparation of tetradecamethylcycloheptaphosphazene, by the methylation of the corresponding fluorophosphazene (NPF2)7 with methylmagnesium bromide, is reported. Crystals of tetradecamethylcycloheptaphosphazene are monoclinic, a = 13.160(1), b = 11.685(1), c = 18.576(1) Å, (β = 108.333(5)°, Z = 4, space group C2/c. The structure was solved by direct methods and was refined by full-matrix least squares procedures to a final R of 0.046 and Rw of 0.063 for 2568 reflections with I ≥ 3σ(I). The molecule has crystallographic C2 symmetry with mean bond lengths (rms deviations from the mean in parentheses, bonds not involving hydrogen have been corrected for libration) P—N, 1.592(6), P—C, 1.804(11), and C—H, 0.94(7) Å, and mean angles in the 14-membered ring are 132.9° at N and 117.1° at P.

L-Proline derivatives of gallium trimethyl and gallium triethyl: crystal and molecular structure of L-prolinatodimethylgallium

1977 ◽  
Vol 55 (24) ◽  
pp. 4174-4179 ◽  
Author(s):  
Kenneth R. Breakell ◽  
Steven J. Rettig ◽  
Alan Storr ◽  
James Trotter
Keyword(s):  
Molecular Structure ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Gallium Atom ◽  
Full Matrix ◽  
Trigonal Bipyramidal ◽  
A Chain ◽  
Proline Derivatives ◽  
Derivatives Of ◽  
Distorted Trigonal Bipyramidal

Crystals of L-prolinatodimethylgallium are orthorhombic, a = 10.624(2), b = 10.567(4), c = 8.2268(6) Å, Z = 4, space group P212121. The structure was solved by direct methods and was refined by full-matrix least squares procedures to a final R of 0.029 and Rw of 0.035 for 1109 reflections with I ≥ 3σ(I). Details of the preparation and physical properties of L-prolinatodimethylgallium and L-prolinatodiethylgallium are given. The crystal structure of L-prolinatodimethylgallium consists of molecules each linked to two others by weak Ga—O bonds (2.695(3) Å) and N—H … O hydrogen bonds (N … O = 2.901(4) Å) to form a chain-like polymeric structure extending along the b axis. The gallium atom is five-coordinate and has distorted trigonal bipyramidal geometry. Important bond lengths are: Ga—O (axial), 2.044(3) and 2.695(3); Ga—N, 2.035(3); and Ga—C, 1.942(5) and 1.958(5) Å

Crystal and molecular structure of dodecamethylcyclohexaphosphazene, (NPMe2)6

1977 ◽  
Vol 55 (17) ◽  
pp. 3118-3123 ◽  
Author(s):  
Richard T. Oakley ◽  
Norman L. Paddock ◽  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Molecular Structure ◽  
Least Squares ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Unit Cell ◽  
Weighted Mean ◽  
Full Matrix ◽  
Space Group ◽  
Bond Lengths ◽  
The Mean

Crystals of dodecamethylcyclohexaphosphazene are triclinic, a = 13.898(1), b = 8.690(1), c = 10.790(1) Å, α = 109.84(1), β = 92.01(1), γ = 106.39(1)°, Z = 2, space group [Formula: see text]. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to a final R of 0.034 and Rw of 0.042 for 4217 reflections with I ≥ 3σ(I). The unit cell contains two independent centrosymmetric molecules which are virtually identical. The 12-membered rings have the 'double tub' conformation. Bond lengths not involving hydrogen have been corrected for libration. Weighted mean bond lengths (rms deviations from the mean in parentheses) are: P—N, 1.593(6), C—P, 1.808(4), and C—H, 0.95(6) Å.

Crystal and molecular structure of B,B-bis(p-tolyl)boroxazolidine and the orthorhombic form of B,B-diphenylboroxazolidine

1976 ◽  
Vol 54 (20) ◽  
pp. 3130-3141 ◽  
Author(s):  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Molecular Structure ◽  
Statistical Analysis ◽  
Hydrogen Bonds ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Length Variation ◽  
Full Matrix ◽  
Space Group ◽  
Phenyl Rings ◽  
Related Compounds

Crystals of B,B-bis(p-tolyl)boroxazolidine, 1c, are trigonal, a = 25.1028(9), c = 12.4184(7) Å, Z = 18, space group [Formula: see text]. And crystals of B,B-diphenylboroxazolidine, 1a, are orthorhombic, a = 17.6420(4), b = 14.2527(3), c = 10.205(1) Å, Z = 8, space group Pbca. Both structures were solved by direct methods and were refined by full-matrix least-squares procedures to final R values of 0.057 and 0.040 for 2230 and 1828 reflections with I ≥ 3σ(I) respectively. Both molecules have structures similar to related compounds and feature intermolecular N—H … O hydrogen bonds (N … O = 2.982(2) for 1c and 2.896(2) Å for 1a). Bond lengths are: for 1c; O—C, 1.413(3), O—B, 1.478(3), N—C, 1.488(3), N—B, 1.657(3), C(sp3)—C(sp3), 1.501(4), B—C, 1.616(3) and 1.623(3), mean C—C(ar), 1.395, N—H, 0.93(2) and 0.94(2), mean C(sp3)—H, 1.00, and mean C(ar)—H, 1.00 Å; for 1a; O—C, 1.409(2), O—B, 1.476(2), N—C, 1.489(2), N—B, 1.655(2), C(sp3)—C(sp3), 1.507(3), B—C, 1.613(2) and 1.620(2), mean C—C(ar), 1.391, N—H, 0.93(2) and 0.92(2), mean C(sp3)—H, 1.00, and mean C(ar)—H, 0.98 Å. A statistical analysis of the phenyl C—C distances in compounds 1a, 1b, and 1c has provided an example of statistically significant substituent-induced bond length variation in the phenyl rings.

Crystal and molecular structure of 2,6-dimethyl-3,5-di[N-methyl]carbamoyl-4-[3,4-methoxy]phenyl-l,4-dihydropyridine hemihydrate and 2,6-dimethyl-3,5-di[N-methyl]carbamoyl-4-[furan]1,4-dihydropyridine

1999 ◽  
Vol 214 (12) ◽  
Author(s):  
M. Bidya Sagar ◽  
K. Ravikumar ◽  
Y. S. Sadanandam
Keyword(s):  
Molecular Structure ◽  
Least Squares ◽  
Crystal Structures ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Asymmetric Unit ◽  
Full Matrix

AbstractThe crystal structures of two dihydropyridines were solved by direct methods and refined by full-matrix least-squares procedure. 2,6-Dimethyl-3,5-di[N-methyl]-carbamoyl-4-[3,4-methoxy]phenyl-1,4-dihydropyridine hemihydrate, CBoth compounds crystallize with two molecules in the asymmetric unit. In compound

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