The crystal and molecular structure of B , B -bis-( p -fluorophenyl)boroxazolidine, ( p -FC 6 H 4 ) 2 BO(CH 2 ) 2 NH 2

. Can. J. Chem. 61, 206 (1983) The reaction of (C6HS)?BOH with salicylaldoxime yielded [ ( C~H S N O~) B C~H~]~ via a boron-carbon bond cleavage rtaction. Crystals of bis[(salicylaldoximato(2-))phenylboron] are triclinic, a-= 9.219(1), b = 11.240(1), c = 12.086(1) A, a = 100.682(7), P = 112.224(6), y = 92.189(7)", Z = 2, space group P 1. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to R = 0.036 and R,,. = 0.049 for 3433 reflections with 1 2 3u(1). The molecule, which has approximate Cz symmetry. contains a system of five fused six-membered rings including the first crystallographically characterized BzNZOz ring. The compound is stabilized both by intramolecular N -z B coordination and by resonance delocalization and contains boron atoms in a distorted tetrahedral environment. Bond lengjhs (corrected for libration) are: 0-B, 1.469(2)-1.488(2), N-B, 1.602(2) and 1.575(2), C-B, 1.598 (2) Intensities were measured with graphite-monochromated Mo-Ka radiation (h = 0.71073 A) on an Enraf-Nonius CAD4-F diffractometer. An w-1.330 scan at 1.12-6.71' min-' over a range of (0.58 + 0.35 tan 0) degrees in w (extended by 25% on both sides for background measurement) was employed. Data were measured to 20 = 55". The intensities of three check reflections, measured every 3600 s throughout the data collection, remained constant to within 3%.

Section: Resultsmentioning

confidence: 94%

Structural studies of organoboron compounds. XIII. Preparation and crystal and molecular structure of bis[(salicylaldoximato(2−))phenylboron]

Rettig¹,

Trotter²

1983

“…Such involvement of fluorine atoms in hydrogen bonding interactions is relatively unusual but not unprecedented, and Glusker and co-workers (26) have recently summarized their status. A more recent structure (27) in which a short intermolecular C-F---H-0 bond is observed has also been published and an earlier study (28) has established the existence of weak C-H---F hydrogen bonds. While such interactions are weak, they are doubtless significant, as evidenced in this case by the high density and low temperature factors observed despite the removal of two hydroxyl groups.…”

Section: Resultsmentioning

confidence: 96%

The preferred conformation of 2-fluoro-2-deoxy β-D-mannopyranosyl fluoride. An X-ray crystallographic and 2-dimensional proton nuclear magnetic resonance study

Withers¹,

Street²,

Rettig³

1986

STEPHEN G. WITHERS, IAN P. STREET, and STEVEN J. RETTIG. Can. J. Chem. 64, 232 (1986). The preferred conformation of 2-fluoro-2-deoxy P-D-mann~pyran~Syl fluoride has been determined in the solid state by X-ray crystallography and in aqueous solution by 2-dimensional J-resolved proton nuclear magnetic resonance. Crystals of 2-fluoro-2-deoxy P-D-mannopyranosyl fluoride are monoclinic, a 4 10.9150(8), b 4 4.9079(4), c 4 6.9902(6) A, P = 105.158(4)", Z = 2, space group P2]. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to R = 0.028 and R,, = 0.031 for 797 reflections with 1 2 3u(I). The sugar ring was present in an essentially undistorted 4CI chair conformation. Weak, but significant interactions, presumably hydrogen bonding of the type OH . .. 232 (1986). On a dCtermin6 la conformation privilCgiCe du fluorure du fluoro-2 dtoxy-2 P-D-mannopyrannosyle tant a 1'Ctat solide en faisant appel diffraction des rayons-X qu'en solution aqueuse en faisant appel a la rmn du 'H bidimensionnelle rCsolue pour J . Les cristaux du fluoru!e du fluoro-2 dCoxy-2 P-D-mannopyrannosyle sont monocliniques avec a= 10,9150(8), b=4,9079(4), c=6,9902(6) A, P = 105,158(4)", Z=2 et groupe d'espace P2'. On a rCsolu la structure par des methodes directes et on l'a affinCe par la mCthode des moindres carrCs (matrice entikre) jusqu'a des valeurs de R=0,028 et R, = 0,03 1 pour 797 rkflexions avec 1 2 3a(I). Le cycle du sucre existe essentiellement dans une conformation chaise 4~1 qui n'est pas dCformCe. Dans la maille du cristal, on observe des interactions faibles, mais significatives, qui sont probablement dues B des liaisons hydrogknes du type OH. . . F et CH . . . F. Les constantes de couplage observtes dans le spectre rmn du 'H en solution ne peuvent &tre expliqukes que par une conformation chaise 4~I .On discute brikvement de ces rksultats par rapport aux rCsultats obtenus rCcemment concernant l'interaction des sucres fluoro-dCoxy avec les sites de liaison enzymatique.[Traduit par le journal] IntroductionThe mode of interaction of carbohydrates and proteins has been attracting considerable interest of late, particularly since the antigenic determinants of red blood cells are oligosaccharides and it is their interaction with receptor proteins that is central to blood type recognition (1). In order to probe the intermolecular forces dominating such interactions, deoxy-and fluorodeoxy-saccharide analogues have been employed in several specificity studies (2-5). Such analogues are useful since the hydroxyl moiety is replaced by a smaller, and therefore sterically compatible, substituent, but one of different electronic properties. Systematic studies of mono-substituted derivatives can therefore provide information on the factors contributing to binding at each position. The enzyme glycogen phosphorylase provides a useful model system for a study of carbohydrate/ protein interactions since the three-dimensional structure of the glycogen phosphorylase/glucose complex has been determined by X-ray ...

“…In 4,4-dimethyl-2,2-diphenyl-1,3-dioxa-4-azonia-2-boranatacy~lopen-tane, 5 (3), which has a non-planar chelate ring, the EL0 distances are 1.506(7) and 1.556 (8) A. The B-0 distances in 1 and 2 are longer than the true single bonds in the tetrahedrally coordinated ethanolamine esters of diarylborinic acids which have a mean bond length of 1.477(5) A (1,2,6) In all three structures, the two B-C distances are somewhat different, this difference being significant only in the case of 2. In both forms of 1 the pseudo-equatorial B-C distances are 0.007 A shorter than the others, the overall mean being 1.606(4) A compared with a mean of 1.605(6) A in 2.…”

Section: Fig 1 Stereoscopic Views Of the Triclinic (Top)mentioning

confidence: 99%

Structural studies of organoboron compounds. XII. Crystal and molecular structures of (acetylacetonato)diphenylboron and (tropolonato)diphenylboron

Rettig¹,

Trotter²

1982

. Can. J. Chem. 60,2957Chem. 60, (1982. There are two crystalline modifications of (acetylacetonato)diphenylboron: triclinic, a = 8.3557(8), b = 9.3519(8), c = 9.6103 (9) A, a = 96.094(5), P = 94.904(6), y = 93.489(6)", Z = 2, space group PT, and monoclinic, a = 11.6329(11), b = 17.1628(8), c = 7.6542(6) A, P = 97.669(4)", Z = 4, space group P2, lc. Crystals of (tropolonato)diphenylboron are monoclinic, a = 12.1596(5), b = 10.2614(4), c = 12.4883(6) A, P = 100.965(2)",Z = 4, spacegroup P2,lc. All threestructures were solvedby direct methodsandwere refined by full-matrix least-squares procedures to R values of 0.046,0.041, and 0.035 for 2465, 2124, and 1722 reflections with 12 3o(I) respectively. Each structure consists of discrete molecules containing tetrahedrally coordinated boron atoms, both the acetylacetonato and tropolonato moieties being delocalized and symmetric. The chelate rings in both forms of (acety1acetonato)-diphenylboron have distorted B-envelope conformations while the chelate ring in (tropo1onato)diphenylboron is essentially planar.The mean l3-0 and B-C distances (corrected for libration) are: 1.543(4) and 1.605(4) A in triclinic, 1.533(3) and 1.607(4) A in monoclinic (acetylacetonato)diphenylboron, and 1.555(11) and 1.605(6) A in (tropolonato)diphenyIboron. Chem. 60, 2957Chem. 60, (1982. L'(acCty1acCtonato)diphenylbore se prCsente sous deux formes cristallines: (a) une forme triclinique appartenant au groupe Chaque structure comprend des molCcules discretes contenant des atomes de bore coordonnts de f a~o n tetraedrique, les deux unites acetylacCtonato et tropolonato Ctant symttriques et dClocalistes. Les cycles du chelate dans les deux formes d'(acttylacttonato) diphtnylbore ont des conformations du type enveloppe B dCformees tandis que le cycle du chClate dans le (tropolonato) diphenylbore est essentiellement plan. Les distances moyennes l3-0 et B-C (corrigkes pour la libration) sont IntroductionExperimental AS part of a continuing study of the molecular The compounds were prepared by reacting (2-aminoethanostructures of organoboron compounds (1-1 1) we 1ato)diphenylboron with the appropriate chelating agent in now report the crystal and molecular structures of ethanollacetone (1:l). With the exception of the solvent used, the procedure is identical to that previously reported for both 1 the acet~lacetOne and trO~O1One esters d i~h e n~l -(12) and 2 (16). Two crystalline modifications of 1 were obtainborinic acid. Both (acety1acetonato)diphenyl-ed. Colorless crvstals of the triclinic form were isolated directly boron, 1, and (tropolonato)diphenylboron~ 2, are stabilized by both intramolecular 0 + B interactions and by electron delocalization in the chelate rings. The chemical and physical properties of these compounds are well documented (12-17 and references therein).'References 1-11 list previous papers in this series.I from the reaction mixture and recrystallization from acetonk afforded colorless crystals of the monoclinic form. High-quality pale yellow crystals of 2 were isolated di...