Abstract

The crystal structure of Li4BN3H10 was investigated using powder neutron diffraction with high sensitivity. The compound crystallizes in the cubic space group 213 with lattice parameters a=10.645 19(52) Å with an ordered arrangement of [NH2]−1 and [BH4]−1 anions in a molar ratio of 3:1. The bond lengths between the nearest nitrogen and hydrogen atoms are 1.04(4) and 1.14(4) Å. The bond angle between H(1)-N-H(2) is about 126(6)°, while those between H(3)-B-H(3) and H(3)-B-H(4) are about 109(6)°-110(7)°. There are three different Li sites surrounded by [NH2]−1 and [BH4]−1 anions in distorted tetrahedral configurations. The Li(3)-B and Li(3)-N bond distances are about 1.72(3) and 2.32(2) Å, respectively, while the Li(1)-N and Li(2)-N distances are both around 2.09 Å. The strong bonding of Li(3) to the [BH4]−1 and the weaker Li(3)-[NH2]−1 bond are evidenced by the presence of the LiBH4 moiety in a projection of the crystal structure onto the a-b plane. First-principle calculations have been performed based on the structural data. Analyses of the density of states and charge density indicate that H(1) and H(2) strongly interact with N, and H(3) and H(4) interact with B to form [NH2]−1 and [BH4]−1, respectively. It is confirmed that Li(1) and Li(2) are strongly bonded to N and Li(3) is strongly bonded to B. These results are significantly different from some of the previous studies.

Department(s)

Physics

Second Department

Chemistry

Sponsor(s)

United States. Department of Energy

Keywords and Phrases

Band Structure; Bond Angles; Bond Lengths; Boron Compounds; Crystal Structure; Lattice Constants; Lithium Compounds; Neutron Diffraction; Space Groups

International Standard Serial Number (ISSN)

0021-8979

Document Type

Article - Journal

Document Version

Final Version

File Type

text

Language(s)

English

Rights

© 2007 American Institute of Physics (AIP), All rights reserved.

Publication Date

01 Aug 2007

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