Biomedical subjects

Trevor R Spalding

Publications and source records attributed to Trevor R Spalding.

6 recordsLinked to original sources

PubMed2006

Pentahapto-bonded gold heteroborane clusters [3-(R3P)-closo-2,1-AuTeB10H10]- and [3-(R3P)-closo-3,1,2-AuAs2B9H9]-.

Gold acetylide compounds [(R3P)AuC[triple bond]CC(Me)(OH)Et], where R = Ph 1 or cyclohexyl (Cy) 2, were synthesised and 2 was characterised using X-ray diffraction techniques. The solid-state structure of 2 contained a two-coordinate gold atom and a linear P-Au-C[triple bond]C-C bonding sequence. The reactions between 1 or 2 and [NR4][nido-7,8-As2B9H10] or [NR4][nido-7-TeB10H10] in ethanol-acetone solvent afforded the twelve-vertex cluster species [NMe4][3-(R3P)-closo-3,1,2-AuAs2B9H9], where R = Ph 5 or Cy 6, or [NEt4][3-(R3P)-closo-2,1-AuTeB10H10], where R = Ph 7 or Cy 8, in moderate or low yields (ca. 35% for , and and ca. 20% for ). Compounds and were characterised with X-ray crystallographic techniques. Although there was crystallographic disorder in the {As2B3} and {TeB4} rings to which the gold atoms were attached, the structures of 5 and 7 strongly suggested that the gold atoms were pentahapto bonded to all the atoms in the {As2B3} or {TeB4} rings giving formally closo cluster geometries with closo cluster electron counts. The solution-phase NMR properties of 5, 6 and 7 were consistent with closo descriptions.

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PubMed2005

Twisted [(R(3)P)PdX] groups above dicarbaborane ligands: 4-dimethylsulfido-3-iodo-3-triphenylphosphine-closo-3-pallada-1,2-dicarbadodecaborane and 3-dimethylphenylphosphine-3-chloro-4-dimethylsulfido-closo-3-pallada-1,2-dicarbadodecaborane.

The structural analyses of [3-(PPh3)-3-I-4-(SMe2)-closo-3,1,2-PdC2B9H10] or [Pd(C4H16B9S)I(C18H15P)], (I), and [3-(PPhMe2)-3-Cl-4-(SMe2)-closo-3,1,2-PdC2B9H10] or [Pd(C4H16B9S)Cl(C8H11P)], (II), show that in comparison with [3-(PR3)2-closo-3,1,2-PdC2B9H11] the presence of the 4-SMe2 group causes the [PdX(PR3)] unit (X = halogen) to twist about an axis passing through the Pd atom and the directly opposite B atom of the carbaborane ligand. The halogen atoms are located almost directly above a C atom in the C2B3 face, and the conformations of the [PdX(PR3)] units above the C2B3 faces are not those predicted from molecular orbital calculations of the closo-3,1,2-PdC2B9 system. The fact that the variation from the predicted conformation is greater in the case of (I) than in (II) may be ascribed to the greater steric interactions induced by the I atom in (I) compared with the Cl atom in (II).

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PubMed2005

Coordination and cluster compounds of ruthenium with the [hypho-1,2-S2B6H9]- ligand.

The reaction between [tmndH][hypho-1,2-S(2)B6H9](tmnd =N,N,N',N'-tetramethylnaphthalene-1,8-diamine) and [RuCl(PPh3)2(eta5-Cp)] in CH2Cl2 at room temperature afforded two ruthenathiaboranes, [5-(eta(5)-Cp)-5-(PPh3)-5,4,6-RuS2B6H9], 1, and [Ru(eta(1)-1,2-S2B6H9)(PPh3)2(eta5-Cp)], 2, in 6 and 48% yields, respectively. The heating of a solution of [Ru(eta(1)-1,2-S2B6H9)(PPh3)2(eta5-Cp)] 2 in CH2Cl2 at reflux temperature afforded 1 in 59% yield. Compound 1 could be described as either a hypho nine-vertex {RuS2B6} cluster or a coordination compound of ruthenium which contains a bidentate eta2-dithiaborate cluster ligand; the latter description is preferred. Compound 2 contains an eight-atom hypho-type {1,2-S2B6} cage bonded to the ruthenium atom of the {Ru(PPh3)2(eta5-Cp)} unit by one sulfur atom and may be described as a compound of ruthenium coordinated eta(1)- to the dithiaborate cluster ligand. The reaction between [tmndH][hypho-1,2-S2B6H9] and [RuCl2(eta6-MeC6H4Pri)]2 in CH2Cl2 at room temperature afforded [5-(eta6-MeC6H4Pri)-arachno-5,4,6-RuS2B6H8], 3, in 94% yield. Further reaction of 3 and PMePh2 afforded another arachno{RhS2B6}cluster, [5-(eta6-MeC6H4Pri)-8-(PMePh2)-arachno-5,4,6-RuS2B6H6], 4, in 25% yield. Compounds 1, 2, and 4 were characterised with single crystal X-ray analyses.

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PubMed2005

Pore size engineering in mesoporous silicas using supercritical CO2.

In this paper we investigate the use of supercritical carbon dioxide (sc-CO(2)) for synthesizing calcined mesoporous silicas with tunable pore sizes, wall thickness, and d spacings. Small angle neutron scattering was used to probe the controlled swelling of the triblock copolymer surfactant templating agents, P123 (PEO(20)PPO(69)PEO(20)), P85 (PEO(26)PPO(39)PEO(26)), and F127 (PEO(106)PPO(70)PEO(106)), as a function of CO(2) pressure. The transition from the liquid crystal phase to the calcined mesoporous silicas, formed upon condensation and drying, was also studied in detail. Powder X-ray diffraction, transmission electron microscopy, and nitrogen adsorption techniques were used to establish pore diameters, silica wall widths, and the hexagonal packing of the pores within the calcined silicas. Using a direct templating method, the diameters of mesopores and the spacing between the pores could be tuned with a high level of precision. The swelling process was observed to have no detrimental effects on the quality of silica formed, a distinct advantage over conventional swelling techniques, and all of the silicas synthesized in this study were highly ordered over distances of at least 2000 A.

Adsorption↗

PubMed2004

The synthesis of matrices of embedded semiconducting nanowires.

In this work we report how single crystal nanowires can be assembled into regular arrays using mesoporous thin films to define the architecture. Mesoporous thin films were prepared by a sol-gel method. These provide films of very regular structure and dimensions. The films produced in this way have almost single crystal like structures and can also exhibit strong epitaxy to the underlying silicon substrate. The films are subjected to a supercritical fluid (SCF) environment in which a precursor is decomposed to yield nanowires of metals, semiconductors or oxides. Using these SCF conditions, pore filling is complete and the products are nanowires which are single crystals and structurally aligned in one direction. The growth mechanism of the nanowires is described and size effects discussed.

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PubMed2002

Structural chemistry of arachno-nonaboranes.

Single-crystal conventional-tube and synchrotron X-ray diffraction studies of the anions in [NMe(4)][arachno-B(9)H(12)-4,8-Br(2)] 1 and K[arachno-B(9)H(14)] 2, and also of the series of adducts [arachno-B(9)H(13)-4-L], where L is P(CCH)(3) (3), NHEt(2) (4), NC(5)H(5) (5), or NH(2)CH(2)Ph (6), are reported. Structural studies of 1-6, determined at low temperatures, located all atoms, including bridging and endo-terminal hydrogen atoms. The basic boron-hydride clusters of these, and of all the other known species with the arachno nine-vertex i-nonanborane geometry reported in the literature, are isostructural and feature three bridging and two endo-terminal hydrogen atoms on the open face. This arrangement is different from that previously reported for Cs[arachno-B(9)H(14)] 7 and for [arachno-B(9)H(13)-4-(NCMe)] 9. However, a new X-ray diffraction data set and refinement experimentally confirm the [3 x mu-H, 2 x endo] arrangement for 9 also. The experimental results for 1-6 support recently reported calculations for [B(9)H(14)](-), which predict both the structures and the (11)B NMR chemical shifts. These conclusions are also supported by calculations for 3, 4, and 9 and also for the [arachno-B(9)H(13)-4-(NCS)](-) anion in [NMe(4)][B(9)H(13)(NCS)] 8.

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