The crystal and molecular structure of 2,2-dimethyl-4,4,6,6-tetrafluorocyclotriphosphazene

1981 ◽  
Vol 59 (15) ◽  
pp. 2364-2367 ◽  
Author(s):  
A. Wallace Cordes ◽  
Paul N. Swepston ◽  
Richard T. Oakley ◽  
Norman L. Paddock ◽  
T. N. Ranganathan
Keyword(s):  
Molecular Structure ◽  
Perturbation Theory ◽  
Title Compound ◽  
Electron Distribution ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Mirror Plane ◽  
Bond Lengths ◽  
Plane Normal ◽  
The Mean

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.

Crystal and molecular structure of diphenylboron N-methylacethydroxamate (4,5-dimethyl-2,2-diphenyl-1,3-dioxa-4-azonia-2-boratacyclopent-4-ene)

1978 ◽  
Vol 56 (12) ◽  
pp. 1676-1680 ◽  
Author(s):  
Steven J. Rettig ◽  
James Trotter ◽  
W. Kliegel ◽  
D. Nanninga
Keyword(s):  
Molecular Structure ◽  
Least Squares ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Heterocyclic Ring ◽  
Mirror Plane ◽  
Full Matrix ◽  
Space Group ◽  
Carbon And Nitrogen ◽  
Bond Lengths

Crystals of diphenylboron N-methylacethydroxamate are orthorhombic, a = 12.5478(8), b = 7.8735(3), c = 13.6809(5) Å, Z = 4, space group Pnam. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to R = 0.037 and Rw = 0.054 for 1265 reflections with I ≥ 3σ(I). The molecule features a five-membered BO2CN ring which lies in the crystallographic mirror plane. The carbon and nitrogen atoms of the heterocyclic ring are positionally disordered. Mean bond lengths (corrected for libration) are: O—B, 1.550(2), B—C, 1.609(2), O—C/N, 1.340(3), C—N, 1.300(2), C/N—CH, 1.470(2), and C—C(phenyl), 1.394(8) Å.

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)°.

Contributions to the Chemistry of Boron, LXXV The Crystal and Molecular Structure of a Tetraazadiborine: 3,6-Bis(dimethylamino)-1,2,4,5-tetramethyl-1,2,4,5,3,6-tetraazadiborine

1976 ◽  
Vol 31 (3) ◽  
pp. 289-293 ◽  
Author(s):  
J. C. Huffman ◽  
H. Fusstetter ◽  
H. Nöth
Keyword(s):  
Molecular Structure ◽  
Title Compound ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Membered Ring ◽  
Unit Cell ◽  
Hydrogen Atoms ◽  
Monoclinic System ◽  
Full Matrix ◽  
Bond Lengths

The title compound crystallizes in the monoclinic system with dimensions of the unit cell a = 14.09(2), b = 8.60(1), c = 11.34(1) Å and β = 101.7°. The space group was determined to be A 2/a with four molecules in the unit cell. The structure was solved by direct methods, and all hydrogen atoms were located. Full matrix refinement led to R = 0.059. The B2N4 six membered ring is nonplanar as expected for an 8π electron heterocycle. The molecule possesses C2 symmetry but the ring itself is near the D2 symmetry as derived from earlier CNDO/S-calculations. The BN bond lengths are 1.43 A, the NN distances 1.43 Å and the average CN distances 1.44 A. The boron atoms and four of the six nitrogen atoms are trigonal-planarly coordinated while the remaining two N-atoms (N1,N2) deviate little, but significantly, from sp2 hybridisation. The structure of the molecule can be interpreted as the best compromise between ΒΝ-π-bonding, nonbonding repulsion between adjacent CH3 groups, and the interaction between neighbouring ‘free pairs of electrons’ of the ring N-N-units.

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.

Crystal and Molecular Structure of B,B- Diphenylboroxazolidine (2-Aminoethyl Diphenylborinate),

1973 ◽  
Vol 51 (8) ◽  
pp. 1288-1294 ◽  
Author(s):  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Molecular Structure ◽  
Hydrogen Bonds ◽  
Least Squares ◽  
Electron Density ◽  
Title Compound ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Chair Conformation ◽  
Full Matrix ◽  
Bond Lengths

Crystals of the title compound are monoclinic, a = 13.840(1), b = 8.9169(5), c = 10.170(1) Å, β = 98.85(1)°, Z = 4, space group P21/n. The structure was determined by direct methods, and refined by electron-density and full-matrix least-squares procedures to R 0.041 for 1458 observed reflections. The five-membered boroxazolidine ring is in the half-chair conformation. Bond angles in the ring range from 99.7° for OBN to 110.1° for BOC. Bond lengths are as follows: mean B—C, 1.611(2), B—N, 1.653(3), B—O, 1.484(3), C—N, 1.485(3), C—O, 1.413(3), mean C—C (aromatic), 1.383(11), and C—C, 1.505(4) Å. The structure consists of discrete molecules linked by O…H—N hydrogen bonds (2.874(2) Å) to form continuous spirals about the 21 axes.

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 difluoroboron N-methylacethydroxamate (2,2-difluoro-4,5-dimethyl-1,3-dioxa-4-azonia-2-boranatacyclopent-4-ene)

1977 ◽  
Vol 55 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Steven J. Rettig ◽  
James Trotter ◽  
W. Kliegel ◽  
D. Nanninga
Keyword(s):  
Molecular Structure ◽  
Least Squares ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Full Matrix ◽  
Space Group ◽  
Bond Lengths

Crystals of difluoroboron N-methylacethydroxamate are monoclinic, a = 5.097(1), b = 10.653(2), c = 11.520(2) Å, β = 103.57(2)°, Z = 4, space group P21/c. The structure was solved by direct methods and was refined by full-matrix least squares procedures to a final R of 0.056 and Rw of 0.077 for 988 reflections with I ≥ 3σ(I). The structure features a planar five-membered BO2CN ring. Bond lengths (corrected for libration) are: B—F, 1.374(3) and 1.381(3), O—B, 1.496(3) and 1.497(3), O—N, 1.349(2), O—C, 1.346(2), C—N, 1.298(3) and 1.458(3), and C—C, 1.468(3) Å.

The crystal and molecular structure of 1,4-diphenyl-2,2′,3,3′,5,5′,6,6′-octamethylcyclo-1,4-diphospha-2,3,5,6-tetrasilahexane, a phosphorus–silicon heterocycle

1979 ◽  
Vol 57 (2) ◽  
pp. 174-179 ◽  
Author(s):  
A. Wallace Cordes ◽  
Paul F. Schubert ◽  
Richard T. Oakley
Keyword(s):  
Molecular Structure ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Chair Conformation ◽  
Monoclinic Space Group ◽  
Single Bond ◽  
X Ray Diffraction ◽  
Full Matrix ◽  
X Ray ◽  
Bond Lengths

The crystal structure of 1,4-diphenyl-2,2′,3,3′,5,5′,6,6′-octamethylcyclo-1,4-diphospha-2,3,5,6-tetrasilahexane, (PhPSi2Me4)2, has been determined by single crystal X-ray diffraction. The crystals are monoclinic, space group P21/c, with a = 9.866(1), b = 11.921(1), and c = 11.324(2) Å, β = 104.31(1)°, Z = 2, and ρcalcd = 1.15 g/cm3. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to a final R of 0.060 and Rw of 0.078, for 1173 reflections with intensities greater than 3σ. The (PhPSi2Me4)2 molecule lies on a crystallographic centre of symmetry, and the six-membered P2Si4 ring has a chair conformation with equatorial phenyl groups. The endocyclic angles at P (104.4(1)°) and Si (104.9(2)°) are intermediate between those found in cyclic hexaphosphine and hexasilane molecules, and the Si—Si and P—Si distances of 2.345(3) and 2.252(4) Å, respectively, correspond to single bond lengths, with no appreciable evidence for secondary pπ → dπ bonding between phosphorus and silicon. The Si—C (1.867(8) Å) and P—C (1.828(7) Å) bond lengths are also normal. The variations in the Si—P—C (101.6(2)°, 108.6(2)°), P—Si—C (range 106.2(3)–120.0(3)°), and Si—Si—C (range 105.8(3)–113.7(3)°) angles indicate that the positions of the exocyclic methyl and phenyl groups are influenced by both intra- and intermolecular steric forces.

The crystal and molecular structure of 1α,9β-Dichloro-2,2,10,10-tetramethoxy[2,2](2,6)pyridinophane

1978 ◽  
Vol 31 (9) ◽  
pp. 1953 ◽  
Author(s):  
D Taylor
Keyword(s):  
Molecular Structure ◽  
Least Squares ◽  
Title Compound ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Maximum Deviation ◽  
Asymmetric Unit ◽  
Space Group ◽  
Block Diagonal

Crystals of the title compound, C18H20Cl2N2O4, are monoclinic, a 14.706(1), b 17.168(1), c 7.269(1) Ǻ, β 92.72(1)°, space group P21/c with Z = 4. The structure was solved from diffractometer data by direct methods. Block-diagonal least-squares refinement converged at R 0.037, Rw 0.045 for 2103 reflections with I ≥ 3σ(I) which had been corrected for absorption (μ 34.0 cm-1). The asymmetric unit is comprised of two independent half-molecules, each molecule being centrosymmetric. The pyridine rings are distorted from planarity, with a maximum deviation of 0.10 Ǻ at the nitrogen atoms, as a consequence of the short intramolecular N...N contacts of 2.476(4) and 2.473(5) Ǻ.

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