Biomedical subjects
Publications and source records attributed to Andrew D Bond.
The low-temperature crystal structures of 1,7-octadiene (C8H14), 1,9-decadiene (C10H18), 1,7-octadiyne (C8H10) and 1,9-decadiyne (C10H14), determined following in situ crystal growth from the liquid, reveal the role of C-H...pi interactions in alpha,omega-unsaturated linear hydrocarbons in the solid state.
Amination of [ClP(micro-NtBu)](2) (1) using NH(3) in THF gives the cyclophospha(III)zane dimer [H(2)NP(micro-NtBu)](2) (2), in good yield. (31)P NMR spectroscopic studies of the reaction of 1 with 2 in THF/Et(3)N show that almost quantitative formation of the cyclic tetramer [[P(micro-NtBu)](2)(micro-NH)](4) (3) occurs. The remarkable selectivity of this reaction can (in part) be attributed to pre-organisation of 1 and 2, which prefer cis arrangements in the solid state and solution. The macrocycle 3 can be isolated in yields of 58-67 % using various reaction scales. The isolation of the major by-product of the reaction (ca. 0.5-1 % of samples of 3), the pentameric, host-guest complex [[P(micro-NtBu)(2)](2)(micro-NH)](5)(HCl).2 THF] (4.2 THF), gives a strong indication of the mechanism involved. In situ (31)P NMR spectroscopic studies support a stepwise condensation mechanism in which Cl(-) ions play an important role in templating and selection of 3 and 4. Amplification of the pentameric arrangement occurs in the presence of excess LiX (X=Cl, Br, I). In addition, the cyclisation reaction is solvent- and anion-dependent. The X-ray structures of 2 and 4.2 THF are reported.
The novel, deca-lithium cage [(mtaNHLi)(As2(Nmta)5)-Li(4).2thf]2 (1) (mtaN = 5-methylthiazolyl, C4H4N2S) contains an imido-bridged tetraanion [(mtaN)2As(mu-Nmta)-As(Nmta)2]4-, which represents a new type of multi-functional imido group 15 ligand framework (homologous with group 15 anions of the type [As(NR)3]3-).
[reaction: see text] The first X-ray crystal structure of a mononuclear metallacyclopentadiene(alkyne) complex has been obtained. This type of metallacycle is believed to be the key intermediate in the cobalt-mediated [2 + 2 + 2]cycloaddition of alkynes. Thermal treatment leads to the generation of angular [4]phenylene, the X-ray structural details of which are described. Under photochemical conditions, the cobaltacycle isomerizes to a highly strained (cyclobutadieno)dibenzocyclooctatrienyne complex.
Reaction of cobalt(II) salts with the thiosalicylate dianion under hydrothermal conditions yields green lamellar Co((O2C)(S)C6H4) which displays canted antiferromagnetism.
In contrast to the reactions of Sn(NMe(2))(2) with unfunctionalized primary amines (RNH(2)), which yield the simple imido Sn(II) cubanes [SnNR](4), the reactions of 2-pyridyl or 2-pyrimidinyl amines give the mixed-oxidation-state Sn(II)/Sn(IV) double cubanes [Sn(7)(NR)(8)]. In addition to [Sn(7)[2-N(5-Mepy)](8)] x 2thf (1 x 2thf) (py = pyridine) and [Sn(7)[2-N(pm)](8)] x 0.33thf (2 x 0.33thf) (pm = pyrimidine), which were communicated previously, the syntheses and structures of the new complexes [Sn(7)[2-N(4-Mepm)](8)] x 2thf (3 x 2thf), [Sn(7)[2-N(4,6-Me(2)pm)](8)] x 4thf (4 x 4thf), [Sn(7)[2-N(4-Me-6-MeO-pm)](8)] (5), and [Sn(7)[2-N(4-MeO-6-MeO-pm)](8)] (6) are reported. Model DFT calculations on the reactions of Sn(NMe(2))(2) with 2-pmNH(2) or PhNH(2), producing the cubanes [Sn[2-N(pm)]](4) and [SnNPh](4) (respectively), and the corresponding double cubanes [Sn(7)[2-N(pm)](8)] and [Sn(7)(NPh)(8)], show that the presence of intramolecular Sn...N bonding which spans the cubane halves of the complexes is crucial to the formation of the double-cubane structure.
A simulated-annealing direct-space approach has been applied to predict the crystal structures of a series of metallo-organic complexes containing Zn, Cu and Ni. The prediction methodology generates a set of energetically reasonable crystal structures among which the actual structure is present, but it is not always possible to specify unambiguously the known crystal structure solely on the basis of energy. In each case, however, the ambiguity may be resolved by recourse to laboratory powder X-ray diffraction (PXRD) data. In this manner, structure prediction is shown to be a powerful tool for structure solution using PXRD data, with the additional advantage that indexing of the PXRD profile is not required at the outset.
The structure of triacetone amine monohydrate (systematic name: 2,2,6,6-tetramethylpiperidin-4-one monohydrate), C(9)H(17)NO.H(2)O, has been redetermined at 180K. The compound crystallizes in space group P2(1)/c with a monoclinic angle of 90.084(3) degree. All crystals examined exhibited twinning and appeared orthorhombic, with a unit-cell volume half that of the true volume.