A binuclear rhodium(I) complex with two tetraphosphine ligands at 100 K

Bis(μ‐3,11‐diethyl‐6,8‐di­phenyl‐3,6,8,11‐tetraphosphatri­dec­ane‐κ⁴P³,P⁶:P⁸,P¹¹)­dirhodium(I) bis­(tetra­fluoro­borate), [Rh₂(C₂₅H₄₀P₄)₂](BF₄)₂, is a bimetallic complex containing two binucleating tetra‐tertiary phosphine ligands. The distance between the metal centers is 5.4555 (11) Å, with no metal–metal bond. The Rh—P bond distances range from 2.2483 (14) to 2.3295 (14) Å. The geometry about the Rh^I atoms is tetrahedrally distorted square planar and the dihedral angle between the two coordination planes is 66.28 (5)°.     

Method of forces for direction finding in interactive multicriterion optimization applications

The main purpose of this paper is to derive, illustrate, and validate a method of direction finding for use in multicriterion interactive optimization applications. A secondary purpose is to consider electronic spreadsheet operation as an instance of interactive multicriterion optimization and to test the new method in a spreadsheet model for aggregate production planning. The method derived here amounts to virtual direct specification of the gradient direction, but does so by an appeal to the simple physical notion of forces applied to the criteria. It is demonstrated that the idea is easily grasped and also gives effective performance in the application tested.The authors are indebted to Professor Carl Langenhop, Mathematics Department, Southern Illinois University at Carbondale for several useful suggestions.     

Photothermal patterning of microgel/gold nanoparticle composite colloidal crystals

We present a new method for laser direct writing in self-assembled hydrogel microparticle colloidal crystals via photothermal excitation of co-assembled colloidal Au particles. Close-packed colloidal crystals are assembled from approximately 224 nm diameter, thermoresponsive, poly-N-isopropylacrylamide hydrogel microparticles (microgels); these crystals display sharp Bragg diffraction peaks in the mid-visible region of the spectrum due to the periodic dielectric function of the assembly. Raising the temperature of the crystal above the characteristic volume phase transition temperature of the microgel particles results in a reversible melting of the crystalline material due to the particle-based deswelling event. This transition can be used either to anneal defects from the crystalline material or to controllably and reversibly convert the assembly from the colored, crystalline state to a nondiffracting glassy material. Crystal-to-glass transitions are similarly accomplished via photothermal excitation when 16 nm diameter colloidal Au particles are co-assembled with the responsive microgels. Excitation of the colloidal Au plasmon absorption with a frequency doubled Nd:YAG laser (lambda = 532 nm) results in optically directed conversion of either glasses to crystals or crystals to glasses, depending on the initial state of the assembly and the illumination time. These results represent a fundamentally new method for the patterning of self-assembled photonic materials.     

Structure of chlorohydroxonitrosyl(terpyridine)ruthenium(II) hexafluorophosphate

The title complex has the NO grouptrans to the hydroxyl ligand and the chloride ion in the plane of the tripyridyl ligand. The Ru−O and Ru−N(O) distances are 1.939(5) ? and 1.764(6) ?, respectively; the Ru−N−O bond angle is 171.7(6)⁰. These values are consistent with previously reported shortening of Ru−O distances whentrans to a linear NO ligand. The space group of the structure isP2₁/c, witha=9.7213(9) ?,b=13.9318(11) ?,c=14.523(4) ?, and β=105.820(13)⁰.     

A conceptual approach to the dilemma of particles and waves of light and matter in something or nothing

It is assumed that all space is filled with extremely small anisotropic particles under subatomic pressure. It is further assumed that the presence of particles of charge, mass, or moving charge cause an orientation distortion of the particles of the medium which respectively constitute electric fields, gravity and magnetic fields.The photoelectric effect is explained on the basis of waves. Negative results of the Michelson—Morley experiment are explained by the expansion of the interferometer arm perpendicular to movement of the medium. The expansion of the arm is caused by the magnetic fields of adjacent unlike charges moving through space. Thus light can be a real wave in a real medium and any corpuscular properties it has can be explained by it being absorbed and radiated by corpuscular electrons.     

Electron stimulated desorption ion angular distributions of H2O and NH3 on Ru(001)

The recent experiments of Madey et al. on the Electron Stimulated Desorption Ion Angular Distributions (ESDIAD) of H₂O and NH₃ on a Ru(001) surface are discussed using the reflection approximation for Franck-Condon ionization. In this approximation, ESDIAD data mirrors, the adsorbate wave function and therefore equilibrium bond angles as well as vibrational information can be extracted from it. It is also shown that image potential distortions of the desorbed ion trajectory from chemical bond directions are easily calculated and could be quite large although considerable uncertainty exists.     

1]molybdarenophanes: strained metallarenophanes with aluminum, gallium, and silicon in bridging positions

The first [1]molybdarenophanes were synthesized and structurally characterized. The aluminum and gallium compounds [(Me2Ntsi)Al(eta6-C6H5)2Mo] (2a) and [(Me2Ntsi)Ga(eta6-C6H5)2Mo] (2b) [Me2Ntsi = C(SiMe3)2(SiMe2NMe2)] were obtained from [Mo(LiC6H5)2].TMEDA and (Me2Ntsi)ECl2 [E = Al, Ga] in analytical pure form with isolated yields of 74% (2a) and 52% (2b). The silicon-bridged species [Ph2Si(eta6-C6H5)2Mo] (2c) was synthesized from [Mo(LiC6H5)2].TMEDA and Ph2SiCl2. Compound 2c was isolated as a crystalline material in an approximately 90% overall purity, from which a single crystal was used for X-ray analysis. The molecular structures of all three [1]molybdarenophanes 2a-c were determined by single-crystal X-ray analysis. The ring-tilt angle alpha was found to be 18.28(17), 21.24(10), and 20.23(29) degrees for 2a, 2b, and 2c, respectively. Variable temperature NMR measurements of 2a and 2b (-80 to 80 degrees C; 500 MHz) showed a dynamic behavior of the gallium species 2b but not of compound 2a. The dynamic behavior of 2b was rationalized by assuming that the Ga-N donor bond breaks, inversion at the nitrogen atom occurs, and a rotation of the Me2Ntsi ligand takes place followed by a re-formation of the Ga-N bond on the other side of the gallium atom. The analysis of the signals of meta and ortho protons of 2b gave approximate values of DeltaG not equal of 59.6 and 59.1 kJ mol-1, respectively. Compound 2b reacted with [Pt(PEt3)3] to give the ring-open product [(eta6-C6H6)Mo{eta6-C6H5[GaPh(Me2Ntsi)]}] (3b). The molecular structure of 3b was deduced from a single-crystal X-ray determination. The formation of the unexpected platinum-free product 3b can be rationalized by assuming that benzene reacted with 2b in a 1:1 ratio. Through a series of 1H NMR experiments with 2b it was shown that small amounts of donor molecules (e.g., THF) in benzene are needed to form 3b; in the absence of a donor molecule, 2b is thermally stable.     

Universality in eight-arm star polystyrene and methylcyclohexane mixtures near the critical point

Measurements of the coexistence curve and turbidity were made on different molecular mass samples of the branched polymer-solvent system eight-arm star polystyrene in methylcyclohexane near its critical point. We confirmed that these systems belong in the Ising universality class. The location of the critical temperature and composition as well as the correlation length, susceptibility, and coexistence curve amplitudes were found to depend on molecular mass and the degree of branching. The coexistence curve diameter had an asymmetry that followed a "complete scaling" approach. All the coexistence curve data could be scaled onto a common curve with one adjustable parameter. We found the coexistence curve amplitude to be about 12% larger for branched than linear polystyrenes of the same molecular mass in either solvent cyclohexane or methylcyclohexane. The two-scale-factor universality ratio R was found to be independent of molecular mass or degree of branching.