Structural studies of organoboron compounds. LVI. 1-Benzyl-7-methyl-3,5-diphenyl-2,4,6-trioxa-1-azonia-3-bora-5-boratabicyclo[3.3.0]octane and 1,4,6,9-tetramethyl-2,7-diphenyl-3,8,11,12-tetraoxa-1,6-diazonia-2,7-diboratatricyclo[5.3.1.12,6]dodecane

1992 ◽  
Vol 70 (11) ◽  
pp. 2809-2817 ◽  
Author(s):  
Wolfgang Kliegel ◽  
Gottfried Lubkowitz ◽  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Solid State ◽  
Gas Phase ◽  
Phenylboronic Acid ◽  
Direct Methods ◽  
Structural Studies ◽  
Triclinic Space Group ◽  
Full Matrix ◽  
X Ray ◽  
Molar Ratios ◽  
New Type

The preparation of the N-(2-hydroxypropyl)-N-alkylhydroxylamines, 6a (R = CH3) and 6b (R = CH2Ph), and their reactions with phenylboronic acid are described. Regardless of the molar ratios of reactants employed, the reaction with 6b leads to the 1:2 condensate 1-benzyl-7-methyl-3,5-diphenyl-2,4,6-trioxa-1-azonia-3-bora-5-boratabicyclo[3.3.0]octane, 7, while that with 6a gives rise to the 1:1 condensate 1,4,6,9-tetramethyl-2,7-diphenyl-3,8,11,12-tetraoxa-1,6-diazonia-2,7-diboratatricyclo[5.3.1. 12,6]dodecane, 11 (the cyclic BONBON dimer of 4,6-dimethyl-2-phenyl-1,3-dioxa-4-aza-2-boracyclohexane, 9). Compounds 7 and 11 both crystallize in the triclinic space group [Formula: see text]: for 7; a = 13.126(1), b = 15.337(1), c = 10.9469(5) Å, α = 91.727(5), β = 104.647(5), γ = 72.922(7)°, Z = 4; and for 11; a = 9.0807(4), b = 9.1653(3), c = 6.4876(2) Å, α = 97.708(3), β = 108.830(3), γ = 89.188(4)°, Z = 1. The structures were solved by direct methods and were refined by full-matrix least-squares procedures to R = 0.038 and 0.032 for 5879 and 1827 reflections with I ≥ 3σ(F2), respectively. Compound 7 has the expected bicyclic pyroboronate structure, but represents the first reported N-substituted example of this type of compound. Bond lengths involving boron in 7 are (C) O—B(sp3) = 1.428(2) and 1.420(2), (B)O—B(sp3) = 1.472(2) and 1.468(2), N—B(sp3) = 1.737(2) and 1.762(2), C(phenyl)—B(sp3) = 1.588(2) and 1.584(2), (N)O—B(sp2) = 1.402(2) and 1.404(2), (B)O—B(sp2) = 1.331(2) and 1.329(2), C(phenyl)—B(sp2) = 1.555(3) and 1.553(2) Å. The X-ray analysis establishes a centrosymmetric, twofold N → B coordinated, dimeric structure in the solid state for 11 in which each B—O—N segment of a central six-membered BONBON ring is bridged by an O—C—C moiety. Compound 11 represents the first fully characterized example of a new type of "BONBON" compound. Bond distances involving the boron atom are (N)O—B = 1.465(1), (C)O—B = 1.428(1), N—B = 1.695(2), and C(phenyl)—B = 1.607(2) Å. Spectroscopic evidence indicates that in solution and in the gas phase this material exists predominantly as the monomer 9.

Physical and structural studies of N-substituted-3-hydroxy-2-methyl-4(1H)-pyridinones

1988 ◽  
Vol 66 (1) ◽  
pp. 123-131 ◽  
Author(s):  
William O. Nelson ◽  
Timothy B. Karpishin ◽  
Steven J. Rettig ◽  
Chris Orvig
Keyword(s):  
Mass Spectrometry ◽  
Hydrogen Bonding ◽  
Solid State ◽  
Single Crystal ◽  
Direct Methods ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Full Matrix ◽  
Space Group ◽  
X Ray

A series of 3-hydroxy-2-methyl-4(1H)-pyridinones has been prepared with the substituents H, CH3, n-C6H11, and CH2CH2NH2 at the ring N. The dipyridinone 1,6-bis(3-hydroxy-2-methyl-4(1H)-pyridinon-1-yl)hexane has also been synthesized. The products with H and CH3 substituents have been studied by single crystal X-ray diffraction. Crystals of 3-hydroxy-2-methyl-4-pyridinone are monoclinic, a = 6.8351(4), b = 10.2249(4), c = 8.6525(4) Å, β = 105.215(4)°, Z = 4, space group P21/n and those of 3-hydroxy-1,2-dimethyl-4-pyridinone are orthorhombic, a = 7.3036(4), b = 13.0490(6), c = 13.7681(7) Å, Z = 8, space group Pbca. Both structures were solved by direct methods and were refined by full-matrix least-squares procedures to R = 0.037 and 0.044 for 914 and 857 reflections with I ≥ 3σ(I), respectively. Bond lengths and angles in the two compounds were normal. All the compounds have been studied by mass spectrometry, and by infrared and proton nmr spectroscopies. The importance of hydrogen bonding to both the solution and solid state properties of these compounds has been confirmed by these techniques.

Physical and structural studies of N-carboxymethyl- and N-(p-methoxyphenyl)-3-hydroxy-2-methyl-4-pyridinone

1992 ◽  
Vol 70 (3) ◽  
pp. 763-770 ◽  
Author(s):  
Zaihui Zhang ◽  
Steven J. Rettig ◽  
Chris Orvig
Keyword(s):  
Mass Spectrometry ◽  
Hydrogen Bonding ◽  
Solid State ◽  
Protonation Constant ◽  
Direct Methods ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Full Matrix ◽  
Space Group ◽  
X Ray

3-Hydroxy-1-carboxymethyl-2-methyl-4-pyridinone (Hcmp) and 3-hydroxy-1-(p-methoxyphenyl)-2-methyl-4-pyridine (Hpap) have been prepared and studied by single crystal X-ray diffraction. Crystals of Hemp are monoclinic, a = 6.340 (2), b = 7.705 (1), c = 16.226 (1) Å, β = 94.74 (1), Z = 4, space group P21/n and those for Hap are monoclinic, a = 10.8435 (9), b = 16.680 (2), c = 13.5665 (6) Å, β = 109.450 (4), Z = 8, space group C2/c. Both structures were solved by direct methods and were refined by full-matrix least-squares procedures to R = 0.030 and 0.041 (Rw = 0.039 and 0.058) for 1642 and 1819 reflections with I ≥ 3σ(I), respectively. Bond lengths and bond angles in the two compounds are normal; however, Hcmp forms as a zwitterion in the solid state. The two compounds were also studied by mass spectrometry, UV, infrared, proton NMR spectroscopies, and potentiometric equilibrium measurements. The protonation constants for Hcmp are log K1 = 9.76 (1), log K2 = 3.43 (1), and log K3 = 2.78 (3) and for Hpap are [Formula: see text] and [Formula: see text]. Keywords: 3-hydroxy-4-pyridinone, zwitterion, hydrogen bonding, protonation constant, crystallography, solid state.

Structural studies of organoboron compounds. XLII. 4,6-Bis(1-cyano-1-methylethyl)-2-mesityl-1,3-dioxa-4,6-diaza-2-boracyclohexane

1991 ◽  
Vol 69 (2) ◽  
pp. 234-238 ◽  
Author(s):  
Wolfgang Kliegel ◽  
Gottfried Lubkowitz ◽  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Least Squares ◽  
Key Words ◽  
Good Yield ◽  
Direct Methods ◽  
Organoboron Compound ◽  
Structural Studies ◽  
Full Matrix ◽  
Bond Lengths

The condensation of N,N′-bis(1-cyano-1-methylethyl)-N,N′-dihydroxymethanediamine and mesitylboronic acid gives 4,6-bis(1-cyano-1-methylethyl)-2-mesityl-1,3-dioxa-4,6-diaza-2-boracyclohexane in good yield. Crystals of the latter compound are orthorhombic, a = 15.825(1), b = 17.958(1), c = 14.014(1) Ǻ, Z = 8, space group Pbca. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to R = 0.037 and Rw = 0.051 for 2844 reflections with 1 ≥ 3σ(I). The molecule has a six-membered cycloboronate structure featuring the first structurally characterized BONCNO ring. The ring was found to have a C-envelope conformation in the solid state. Bond lengths include: O—B(sp2) = 1.356(2) and 1.370(2), and C(aryl)—B = 1.560(2) Ǻ. Key words: organoboron compound, boron compound, crystal structure.

Structural studies of organoboron compounds. LIII. N,N-Diethylhydroxylamine-(O-B)1,7-dimethyl-3,5-diphenyl-2,4,6-trioxa-7-aza-1-azonia-3-bora-5- boratabicyclo[3.3.0]octane

1992 ◽  
Vol 70 (7) ◽  
pp. 2022-2026 ◽  
Author(s):  
Wolfgang Kliegel ◽  
Gottfried Lubkowitz ◽  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Hydrogen Bond ◽  
Least Squares ◽  
Title Compound ◽  
Condensation Product ◽  
Phenylboronic Acid ◽  
Direct Methods ◽  
High Yield ◽  
Structural Studies ◽  
Full Matrix ◽  
Bond Lengths

Reaction of the condensation product of N,N′-dimethyl-N,N′-dihydroxymethanediamine and phenylboronic acid with N,N-diethylhydroxylamine gives N,N-diethylhydroxylamine(O-B)1,7-dimethyl-3,5-diphenyl-2,4,6-trioxa-7-aza-1-azonia-3-bora-5-boratabicyclo[3.3.0]octane [3-(2-ethyl-1-oxa-2-azoniabutyl)-1,7-dimethyl-3,5-diphenyl-2,4,6-trioxa-7-aza-1-azonia-3,5-diboratabicyclo[3.3.0]octane, 3] in high yield. Crystals of 3 are orthorhombic, a = 11.8132(11), b = 15.4768(11), c = 11.7325(16) Å, Z = 4, space group P212121. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to R = 0.039 and Rw = 0.044 for 1729 reflections with I ≥ 2σ(I). The title compound is the second example of this recently characterized class of O-B coordinated hydroxylamine complexes, stabilized by an intramolecular [Formula: see text] hydrogen bond [Formula: see text]. Bond lengths about boron are: B—O(N) = 1.482(4)–1.526(4), B—O(B) = 1.412(4) and 1.420(4), B—N = 1.712(4), B—C = 1.591(5) and 1.602(5) Å.

Structural studies of organoboron compounds. XXXII. 5,5-Difluoro-2,2-pentamethylene-1,4,6-trioxa-3a-azonia-5-borata-1,2,3,4,5,6-hexahydrobenzo[h]azulene and 2,2-pentamethylene-5,5-diphenyl-1,4,6-trioxa-3a-azonia-5-borata-1,2,3,4,5,6-hexahydrobenzo[h]azulene

1988 ◽  
Vol 66 (10) ◽  
pp. 2621-2630 ◽  
Author(s):  
Wolfgang Kliegel ◽  
Mahmood Tajerbashi ◽  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Solid State ◽  
Physical Properties ◽  
Least Squares ◽  
Crystal Structures ◽  
Direct Methods ◽  
Structural Studies ◽  
Full Matrix ◽  
Space Group ◽  
Bond Lengths ◽  
Conformational Isomers

Details of the syntheses, physical properties, and crystal structures of the title compounds are reported. Crystals of 5,5-difluoro-2,2-pentamethylene-1,4,6-trioxa-3a-azonia-5-borata-1,2,3,4,5,6-hexahydrobenzo[h]azulene are triclinic, a = 6.1576(3), b = 11.2651(3), c = 10.8118(3) Å, α = 109.747(3), β = 105.807(4), γ = 92.976(4)°, Z = 2, space group [Formula: see text], and those of 2,2-pentamethylene-5,5-diphenyl-1,4,6-trioxa-3a-azonia-5-borata-1,2,3,4,5,6-hexahydrobenzo[h]azulene are monoclinic, a = 9.8549(6), b = 10.9242(6), c = 41.263(2) Å, β = 92.717(6)°, Z = 8, space group P21/n. Both structures were solved by direct methods and were refined by full-matrix least-squares procedures to R = 0.045 and 0.042 for 2344 and 4248 reflections with I ≥ 3σ(I), respectively. The molecules were both found to possess a seven-membered chelate structure, the O,O-chelatїng ligand being strongly bound to the X2B moiety. Two conformational isomers of the X = Ph compound were found in the solid state. The 2-oxazoline N-oxide moieties present in both compounds are the first to be structurally characterized. Important mean libration-corrected bond lengths are: O—B = 1.491 and F—B = 1.387 Å for X = F; O—B = 1.511 and C—B = 1.620 Å for X = Ph.

Structural studies of organoboron compounds. LX. Reaction of sterically hindered arylboronic acids with 2-(hydroxyamino)alkanols. Crystal and molecular structure of 2-mesityl-6,6-pentamethylene-1,3-dioxa-4-aza-2-boracyclohexane

1994 ◽  
Vol 72 (4) ◽  
pp. 1154-1161 ◽  
Author(s):  
Wolfgang Kliegel ◽  
Gottfried Lubkowitz ◽  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Molecular Structure ◽  
Least Squares ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Structural Studies ◽  
Full Matrix ◽  
Space Group ◽  
X Ray ◽  
Arylboronic Acids ◽  
Sterically Hindered

Three 2-(hydroxyamino)alkanols have been reacted with sterically hindered arylboronic acids, ArB(OH)2. When Ar = o-tolyl, 1:2 condensates having bicyclic structures are formed but when Ar = mesityl (2,4,6-(CH3)3C6H2), 1:1 condensates having six-membered cycloboronate structures result. These 1:1 condensates represent the first examples of N-unsubstituted 1,3-dioxa-4-aza-2-boracyclohexane derivatives. An X-ray analysis of one example provides unambiguous proof of the structure. Crystals of 2-mesityl-6,6-pentamethylene-1,3-dioxa-4-aza-2-boracyclohexane, 3c, are monoclinic, a = 11.076(9), b = 23.94(2), c = 13.414(9) Å, β = 109.40(5)°, Z = 8, space group P21/n. The structure was solved by direct methods and refined by full-matrix least-squares procedures to R = 0.051 and Rw = 0.058 for 2037 reflections with I ≥ 3σ(F2).

A Conformational Study of the Semisynthetic Ergot Alkaloid - Terguride

1993 ◽  
Vol 58 (12) ◽  
pp. 2944-2954 ◽  
Author(s):  
Michal Hušák ◽  
Bohumil Kratochvíl ◽  
Petr Sedmera ◽  
Josef Stuchlík ◽  
Alexandr Jegorov
Keyword(s):  
Solid State ◽  
Ergot Alkaloid ◽  
Direct Methods ◽  
2D Nmr ◽  
Free Base ◽  
Conformational Study ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
X Ray ◽  
Nmr Techniques

Conformational analysis studied by 2D NMR techniques and X-ray diffraction methods are reported for the semisynthetic ergot alkaloid - terguride, in the form of free base and as the protonated species. The structure of terguride hydrogen maleate monohydrate (C20H29N4O)+(C4H3O4)- . H2O (II) was solved by direct methods and refined anisotropically to an Rvalue of 0.068 for 1 991 unique observed reflections. The title compound crystallizes in the triclinic space group P1 with lattice parameters a = 7.061(2), b = 9.205(1), c = 12.223(4) Å, α = 96.36(2), β = 107.15(2), γ = 106.67(1)°. Studies revealed that terguride monohydrate (I) and its protonized form (terguride hydrogen maleate monohydrate) possesses the identical conformations both in solutions and in the solid state - an envelope for C and Chair for D ergoline rings.

Structural studies of organoboron compounds XLVIII. 1,4-Diphenyl-3,3:6,6-bis(tetramethylene)-2,5,7-trioxa-3,6-diazonia-1,4-diboratabicyclo[2.2.1]heptane

1991 ◽  
Vol 69 (8) ◽  
pp. 1222-1226 ◽  
Author(s):  
Wolfgang Kliegel ◽  
Ulf Riebe ◽  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Crystal Structure ◽  
Phenylboronic Acid ◽  
Direct Methods ◽  
Organoboron Compound ◽  
Ring System ◽  
Structural Studies ◽  
Full Matrix ◽  
Moderate Yield ◽  
Atom Bond ◽  
Axis Passing

The reaction of N-hydroxypyrrolidine with either oxybis(diphenylborane) or phenylboronic acid gives 1,4-diphenyl-3,3:6,6-bis(tetramethylene)-2,5,7-trioxa-3,6-diazonia-1,4-diboratabicyclo[2.2.1]heptane in moderate yield. Crystals of the product are orthorhombic, a = 10.984(2), b = 14.619(2), c = 12.311(2) Å, Z = 4, space group Pccn. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to R = 0.039 and Rw = 0.043 for 908 reflections with I ≥ 3σ(I). This is the first heterocyclic [2.2.1]heptane system containing a six-membered BONBON ring and a B—O—B bridge to be structurally characterized. The molecule has exact C2 symmetry with the twofold axis passing through the bridging oxygen atom. Bond lengths involving the tetrahedrally coordinated boron atom are B—O(B) = 1.423(3), B—O(N) = 1.497(3), B—N = 1.703(3), and B—C(phenyl) = 1.577(4) Å. Key words: 2,5,7-trioxa-3,6-diazonia-1,4-diboratabicyclo[2.2.1]heptane ring system, crystal structure, organoboron compound.

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.

Structural studies of organoboron compounds. XXI. Crystal and molecular structures of 3-(phenylmethylidene)-4-methyl-1-phenyl-2,6,7-trioxa-3-azonia-1-boratabicyclo-[2.2.2]octane and N-(4-nitrophenylmethylidene)-5-methyl-2-phenyl-1,3-dioxa-2-bora-5-cyclohexaneamine N-oxide

1985 ◽  
Vol 63 (2) ◽  
pp. 509-515 ◽  
Author(s):  
W. Kliegel ◽  
L. Preu ◽  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Least Squares ◽  
Phenylboronic Acid ◽  
Direct Methods ◽  
Molecular Structures ◽  
Structural Studies ◽  
Full Matrix ◽  
Space Group ◽  
Condensation Products ◽  
Crystal And Molecular Structures ◽  
Bicyclic Structure

Crystals of 3-(phenylmethylidene)-4-methyl-1-phenyl-2,6,7-trioxa-3-azonia-1-boratabicyclo[2.2.2]octane are orthorhombic, a = 8.0732(7), b = 11.8499(10), c = 31.679(2) Å, Z = 8, space group Pbca, and those of N-(4-nitrophenylmethylidene)-5-methyl-2-phenyl-1,3-dioxa-2-bora-5-cyclohexaneamine N-oxide are monoclinic, a = 6.1873(6), b = 23.206(2), c = 11.3081(11) Å, β = 92.326(5)°, Z = 4, space group P21/n. Both structures were solved by direct methods and were refined by full-matrix least-squares procedures to final R values of 0.041 and 0.036 for 943 and 1679 reflections with I ≥ 3σ(I), respectively. Both compounds are condensation products of bis(hydroxyalkyl)nitrones and phenylboronic acid. 3-(Phenyl-methylidene)-4-methyl-1-phenyl-2,6,7-trioxa-3-azonia-1-boratabicyclo[2.2.2]octane was found to possess a bicyclic structure resulting from intramolecular O → B coordination (O—B = 1.604(7) Å) and is the first such bicyclic boron compound to be structurally characterized. In N-(4-nitrophenylmethylidene)-5-methyl-2-phenyl-1,3-dioxa-2-bora-5-cyclohexaneamine N-oxide, which has weakened nitrone basicity, the O → B interaction does not occur, resulting in a monocyclic system incorporating a trigonal planar boron atom.

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