Poster Sessions C684 metal-hydrogen systems. To study structure of liquid transition metal hydrogen alloys, we have performed in-situ energy-dispersive x-ray diffraction measurements at high pressures and high temperatures using a cubic-type multi-anvil press on BL14B1 at SPring-8 synchrotron facility. Pure metal wire was used as a starting material and LiAlH 4 was used as a hydrogen source. The x-ray diffraction measurements on liquid pure metals were also performed for comparison. FeH x is one of the most studied hydrides under high pressure. A solubility of hydrogen in iron is small at ambient conditions but iron and hydrogen react under high pressure and FeH x (x≈0.8) is formed at 6.7GPa and 250°C [1]. The melting temperature of FeH x has been reported by several groups and it is lower than that of pure iron by 500°C at 5 GPa [2], [3]. Our X-ray measurements confirmed the hydrogenation of iron and the decrease of the melting temperature. The pair correlation functions, which are obtained by Fourier transformation of structure factor, indicate that the Fe-Fe nearest neighbor distance in FeH x is slightly longer than that in pure Fe [4]. Similar amount of elongations of the atomic distance were observed also in NiH x and CoH x. In spite of a suggestion of a large decrease of melting temperature in VH x [5], we have not observed melting transition in our X-ray measurements for VH x. We thank Y. Fukai for discussion.
The oxidative addition of B-B bonds of diboranes(4) to late transition metal centres affording bis(boryl)complexes [L n M(BR 2 ) 2 ] [1,2] is of great importance because it constitutes the key step in metal-mediated diboration reactions of unsaturated substrates under both homogeneous [3,4] and heterogeneous [5] conditions. Based on facile oxidative addition of B-Br and B-I bonds to Pt(0) centres [6], we became interested in the reactivity of diboranes(4) Br 2 B 2 R 2 (R = NMe 2 , Mes) towards low-valent phosphine platinum complexes. We have now successfully accomplished the synthesis of two different types of diboranyl (4) , which features a dative bond from the platinum to the second boron atom, resulting in a distorted square-pyramidal geometry of the platinum centre [7]. In course of this reaction the released phosphine PEt 3 reacts with one equivalent of diborane (4) [1] Ishiyama, T., Matsuda, N., Miyaura, N. & Suzuki, A. (1993 O] n The compound crystallizes in the centrosymmetric monoclinic space group P2 1 /c with a = 8.2223(3), b = 18.9945(6), c = 11.7819(4) Å, b = 123.902(2)°a nd Z = 4. The Ba 2+ ion, surrounded by O-and N-atoms, has nine coordination and the complex forms a polymer that extends parallel to the a-axis. The molecular structure is stabilized by O¯H···O and C¯H···O intermolecular hydrogen bonds.The geometric parameters which are obtained from X-ray diffraction and the theoretical parameters for the asymmetric unit which are calculated by using density functional theory (B3LYP) with the 6-31G basis sets are compared. Furthermore, molecular electrostatic potential map and frontier molecular orbital calculations together with experimental and theoretical IR studies were made for this structure.
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