Theoretical study of rhodium(I) carbene complexes: the structural versatility of phosphino- compared with aminocarbenes

Density functional calculations are reported for complexes of general formula [(carbene)RhClL(2)] featuring model phosphino- and aminocarbenes. Both the cis and trans isomers of the rhodium(I) eta(1)-complexes (1-9) were investigated, and the influence of the rhodium co-ligands (L=ethylene, phosphine, or carbon monoxide) was evaluated. In the case of phosphinocarbenes and carbon monoxide as a ligand, a somewhat unusual coordination mode was observed, in which a significant intramolecular Cl-->C(carbene) interaction is present. The propensity of phosphino- and aminocarbenes to behave as four electron donors was also investigated both structurally and energetically on the related eta(2)-complexes 10-18. These results as a whole emphasize the structural versatility of phosphino- compared with aminocarbene complexes.     

Evidence of Vibrational-Induced Rotational Axis Switching for HD(12)C(16)O: New High-Resolution Analysis of the nu(5) and nu(6) Bands and First Analysis of the nu(4) Band (10-µm Region)

Using new high-resolution Fourier transform spectra recorded in Giessen in the 8-12 μm region, a more extended analysis of the nu(5) and nu(6) bands and the first high-resolution study of the nu(4) band of HDCO were performed. As pointed out previously [M. Allegrini, J. W. C. Johns, and A. R. W. McKellar, Can. J. Phys. 56, 859-864 (1978)], the energy levels of the 5(1) and 6(1) states are strongly coupled by A- and B-type Coriolis interactions. On the other hand, it appeared that weaker resonances involving the energy levels of the 4(1) state with those of the 5(1) and 6(1) states also had to be accounted for. Consequently, the calculation of the energy levels was performed taking into account the Coriolis-type resonances linking the energy levels of the {6(1), 5(1), 4(1)} resonating states. Because of the unusually strong Coriolis interaction between nu(5) and nu(6), a nonclassical behavior of the rotational levels of the 5(1) and 6(1) states was observed and it was necessary to use a new Hamiltonian matrix which possesses, as usual, both A- and B-type Coriolis operators in the 5(1) if 6(1) and 6(1) if 4(1) off diagonal blocks but differs from the classical reduced Hamiltonian which is used commonly for planar C(s)-type molecules. More precisely, it proved necessary to include non-orthorhombic terms in the expansion of the rotational Hamiltonian of the 5(1) and 6(1) states. According to the considerations developed by Watson [J. K. G. Watson, in "Vibrational Spectra and Structure," (J. Durig, Ed.), Chap. 1, Elsevier, Amsterdam, 1977], these non-orthorhombic operators which are not symmetry forbidden are usually removed for semirigid C(s)-type molecules by rotational contact transformations. In the present study, the occurrence of terms in {J(x), J(z)} in the expansions of the rotational Hamiltonians for the 5(1) and 6(1) states indicates that the inertial system of HDCO differs for each of the three {6(1), 5(1), 4(1)} resonating states. Therefore, HDCO becomes a good example of vibrational-induced rotational axis switching (VIRAS) which was already suggested as the mechanism responsible for the enhanced densities of coupled states observed in 2-fluoroethanol [H. Li, S. Erza, and L. A. Philips, J. Chem. Phys. 97, 5956-5963 (1992)]. Copyright 2000 Academic Press.     

Anisotropic nonlinear elastic properties of an icosahedral quasicrystal

We show that the nonlinear behavior of transverse acoustic waves can reveal the anisotropic structure of an icosahedral quasicrystal, at the macroscopic level. We report experiments performed in i-Al-Pd-Mn. We observe that a primary transverse acoustic wave can generate a second harmonic transverse acoustic wave. We also observe a specific relation between the polarization directions of those waves. These observations are manifestations on a macroscopic scale of the long-range order in quasicrystals.     

IMP321 (sLAG-3), an immunopotentiator for T cell responses against a HBsAg antigen in healthy adults: a single blind randomised controlled phase I study

Background  

LAG-3 (CD223) is a natural high affinity ligand for MHC class II. The soluble form (sLAG-3) induces maturation of monocyte-derived dendritic cells in vitro and is used as a potent Th1-like immune enhancer with many antigens in animal models. To extend this observation to human, a proof of concept study was conducted with a clinical-grade sLAG-3, termed IMP321, coinjected with alum-non-absorbed recombinant hepatitis B surface antigen.