Showing papers by "Peter S. White published in 1995"

Synthesis of Nanocrystalline Indium Arsenide and Indium Phosphide from Indium(III) Halides and Tris(trimethylsilyl)pnicogens. Synthesis, Characterization, and Decomposition Behavior of I3In.cntdot.P(SiMe3)3

Abstract: : Nanocrystalline indium arsenide and indium phosphide were synthesized by heating the products of the independent 1:1 mole ratio reactions of InX3 (X = Cl, Br, I) with As(SiMe3)3 and P(SiMe3)3, respectively, and the 2:1 mole ratio reaction of InCl3 with As(SiMe3)3. The 1:1 mole ratio reaction of As(SiMe3)3 with InCl3 produced a black powder, which after annealing at 400 deg C afforded InAs crystallites of up to 99.96% purity with an average domain size of 9 nm. InAs obtained from the separate 1:1 mole ratio reactions of InBr3 and InI3 with As(SiMe3)3 and the 2:1 mole ratio reaction of InCl3 with As(SiMe3)3 consisted of crystallites with average domain sizes of 10, 12, and 16 nm, and purities of 99.65%, 85.95%, and 87.90%, respectively. The independent 1:1 mole ratio reactions of InCl3 and InBr3 with P(SiMe3)3 both produced colored powders, which after annealing afforded nanocrystalline InP particles with respective purities of 91.53% and 93.08% and average domain size of approximately 4 nm for both samples. The 1:1 mole reaction of InI3 with P(SiMe3)3 afforded the 1:1 adduct I3In.P(SiMe3)3 (I). Compound 1 crystallizes in the monoclinic system, space group P (2 sub 1/c), with a = 16.074(7), b = 9.730(3), C = 16.454(6) A, V = 2362.1(15) A(3), D(sub calc) = 2.098 g/cu cm for Z = 4; the In-P bond length is 2.537(3) A. Decomposition of 1 affords nanocrystalline InP of 84.06% purity with an approximate average domain size of 2.5 nm. jg

Cyano-Bridged Complexes of trans-Tetrakis(pyridine)ruthenium(II)

Abstract: (3). This transformation causes a marked increase in the electronic coupling through the central Ru unit, as evidenced by a AEID value of 280 mV for the outer RulIml couples in 3. The single-crystal X-ray structures of trans-Ru(CN)2(py)4*2CH3CN and ~~~~~-[C~(~~)~RU(NC)RU(~~)~(CN)RU(~~)~C~I(PF~)~*~CH~CNC~H~N (~~CH~CNCSH~N) have been determined. The complex trans-Ru(CN)~(py)4*2CH3CN, chemical formula C26H26NgRu, crystallizes in the orthorhombic system, space group Pbcn with a = 10.4714(11) A, b = 15.0098(18) A, c = 16.1018(15) A, and Z = 4. The salt 2*5CH3CNCsHsN, chemical formula C~~H~OC~~FI~NZOP ZRU~, crystallizes in the orthorhombic system, space group Pnnm with u = 14.882(7) A, b = 23.197(6) A, c = 24.034(7) A, and Z = 4. The binding of two trans-{RuCl(py)4}+ groups has very little effect on the geometry of the trans-Ru(CN)2(py)4 unit. The complex in 2 has an almost perfectly linear geometry with eclipsed tr~ns-{Ru(py)4}~+ and bond lengths indicating dn(Ru“) - n*(CN) back-bonding from both C- and N-bonded Ru centers. The Ru-C1 bond length is 2.4212(24) A.

On the Baylis–Hillman reaction of acrylate, acrylonitrile, and acrolein with some non-enolizable α-dicarbonyl compounds: synthesis of phytotoxic bipolaroxin models

Abstract: The Baylis–Hillman reaction of acrylonitrile, methyl acrylate, and acrolein with several cyclic α-dicarbonyl compounds was investigated. Whereas acrylonitrile reacted with most of these ketones, giving good yields of the expected 1′-cyanovinyl carbinols, the more sterically demanding methyl acrylate failed to undergo the reaction. Attempted Baylis–Hillman reaction of acrolein with the 1,2-dicarbonyl substrates usually resulted in polymers but, in two cases, the desired α-substituted acroleins were obtained. An alternative route to such compounds was developed, employing a Grignard – allylic oxidation sequence. In bioassays, some of the products, embodying the functionality believed responsible for the phytotoxicity of the sesquiterpene bipolaroxin, inhibited germination of lettuce seeds. This activity diminished with time. Keywords: Baylis–Hillman, acrylonitrile, acrylate, acrolein, α-dicarbonyl, bipolaroxin, phytotoxicity.

The Structures of [X2Y ? N ? YX2]+ Cations (X F, Cl; Y S, Se). A Comparison of X‐ray and ab Initio Studies[1]

Abstract: The structures of cationic species of the series [X2YNYX2]+ (X F, Cl; Y S, Se) have been computed ab initio using all electron treatments for first-row elements and sulfur and quasi-relativistic pseudopotentials for Se and Cl. Splitvalence basis sets with polarization and diffuse functions were employed. The MP2 results for the (non-isostructural!) cations [Cl2SeNSeCl2]+ (1: Cs) and [F2SNSF2]+ (2: C2v) are in excellent agreement with the experimental (X-ray) observations. Both structures represent local minima. A deeper minimum for either of the cations is represented by another C2v isomer which for crystal lattice energy reasons is stable in the isolated state only. The geometries of the hitherto unknown species [Cl2SNSCl2]+ (3) and [F2SeNSeF2]+ (4) have been assessed by ab initio HF calculations. In analogy to 2, cations 3 and 4 are predicted to prefer C2v symmetry. Therefore, 1 exhibits unusual structural features. According to strictly localized natural bond orbital analysis (NBO), the central nitrogen atoms in 1 and 2 possess two lone pairs of electrons (LP: one sp hybrid and one p orbital). The relatively short SeN and SN bond distances in 1 (1.741–1.760 A) and 2 (1.551 A) can best be attributed to LP(N)s*(YX) negative hyperconjugation (1: Y Se, X Cl; 2: Y S, X F).

Synthesis and Complete Characterization of a Gallium-Mixed-Pnicogen Four-Membered-Ring Compound:

Abstract: The first four-membered ring compound containing two gallium atoms bridged by two different Group 15 elements. (1), to be completely characterized was synthesized by both the equilibration of [I2G a As (SiMe3)2]2 (2) and [I2GaP(SiMe3)2]2 (3) in a 1 : 1 mole ratio and the direct reaction of GaI3 with As (SiMe3)3 and P(SiMe3)3 in a 2 : 1 : 1 mole ratio. Single-crystal X-ray structures were determined for both 1 and 3. Crystals of 1 belong to the orthorhombic system, space group Pbca, with a = 17.349(3), b = 13.9187(21), c = 13.7570(24) A, V = 3322.0(10) A3, D calc = 1.879 g cm−3 for Z = 4; the average Ga-As/P bond length is 2.44 A, and crystals of 1 are isomorphous with those of 2. Crystals of 3 belong to the monoclinic system, space group P21/c, with a = 11.040(9), b = 10.228(4), c = 19.619(9) A V = 2169.4(22) A3, D calc = 1.816 g cm−3 for Z = 4; the average Ga-P bond length is 2.39 A.

Postumus, Curtius Postumus, and Rabirius Postumus

Abstract: of o + vocative and mi/mea + vocative, it does not do so within a clearly defined social register in the way that Latin does; for the ubiquitous Latin amabo there is no exact Greek equivalent,30 while the exclusively female exclamation au not only has no effective Greek equivalent,31 but is overwhelmingly a Terentian usage (there being only one example in the whole of Plautus). In all the above cases Pythias' use of the idioms needs to be seen against both the Menandrean norm and the practice of other female speakers in Terence. We must then add instances where Pythias uses words or phrases that are otherwise male gender markers (e.g.,furcifer [862], apage [904], pro deumfidem [943]). In most, if not all, of the foregoing cases we can be reasonably sure that Terence has given to Pythias' utterances an emphasis that was not present in Menander's Greek.32