Journal of Inclusion Phenomena 5 (1987), 605-610. 605 9 1987 by D. Reidel Publishing Company. Indium-Based Liquid Clathrates. I. The Preparation of the First Indium Liquid Inclusion Compound and Crystal Structure of its Parent Complex, [K. 18-Crown-6]a[InClI2(CH3) ] [InClI(CH3)2] ELIZABETH A. BABAIAN, LAURA M. BARDEN, and DUANE C. HRNCIR ~r Department of Chemistry, Universityof Texas at Dallas, Richardson, TX 75083, U.S.A. WILLIAM E. HUNTER and JERRY L. ATWOOD ~r Department of Chemistry, University of Alabama, University,AL 35486, U.S.A. (Received: 12 September 1986; in final form: 12 November 1986) Abstract. The synthesis of the first liquid clathrate derived from an indium precursor is described. The aromatic/anion ratio of the inclusion complex prepared using benzene is 12.4. The use of toluene results in the inclusion of 10.3 guest toluene molecules/anion. The crystal structure of the parent complex, [K. 18- Crown-6]2[InClI2(CH3)] [InCII(CH3)2] was carried out. The compound belongs to the monoelinie space group P2~/c, with a = 19.508(9), b = 8.503(5), and c = 29.437(9) A, fl = 96.55(3) ~ and D~ac = 1.83 gcm 3 for Z = 4. Least-squares refinement based on 3449 observed reflections led to a final R = 0.099. The structure displays two different environments for the two K + cations in the asymmetric unit. One adopts the near-planar [K- 18-crown-6] + configurationwhile the other K + resides 0.81/~ above the second 18-crown-6 plane. The latter K + is apparently pulled out of the crown by a strong interaction with a CI- ion. Key words: Liquid clathrate, indium, erystal structure, 18-crown-6. Supplementary Data related to this article are deposited with the British Library as Supplementary Publication No. SUP 82046 (25 pages). 1. Introduction The interaction between organometallic salts and aromatic molecules has been extensively studied over the past several years [ 1 ]. The vast majority of the work has been conducted on host compounds of the type M[AleR6X], where M is an alkali metal or tetraalkylammonium cation, R is a methyl or ethyl group, and X is a halide or pseudohalide anion. The organometallic precursor to these compounds has always been the trialkylaluminum, AI(CH3) 3 or AI(C2Hs) 3. Recently, liquid clathrates have been prepared from other aluminum compounds such as (CzHs)A1C12 and even A1C13 [2]. The other members of Group III, B-T1, have largely been neglected. Trimethylgallium exhibits similar chemistry to its aluminum congener and several liquid clathrates based upon gallium have been prepared [3]. It is possible that thallium may be excluded from the traditional role in the anion, [T12R6X ] -, due to its preference for the 1 + oxidation state. There has been no mention of using boron or indium complexes as precursors to liquid inclusion compounds. ~r Authors for correspondence.