Two Novel Lithium-15-Crown-5 Complexes: An Extended LiCl Chain Stabilized by Crown Ether and a Dimeric Complex Stabilized by Hydrogen Bonding with Water.

Two lithium chloride-15C5 (15C5 = 15-crown-5) complexes, [Li(15C5)(&mgr;-Cl)(2)Li](infinity), 1, and {[Li(15C5)(H(2)O)]Cl}(2), 2, were synthesized. Their structures, characterized by single-crystal X-ray diffraction analyses, are dictated by the absence of or presence of water. Complex 1, prepared in an anhydrous environment, is the first example of an extended LiCl chain structure. It contains repeating units Li(&mgr;-Cl)Li(15C5) that are connected by additional bridging Cl atoms. One Li has close contacts with one Cl and all five O atoms of 15C5 and the other Li with three Cl and one O of 15C5. However, the chain structure cannot form in the presence of water. Instead dimeric complex 2 was formed when LiCl.xH(2)O (x = 1.14) was the starting material. In this case H(2)O is coordinated to lithium through a Li-O linkage and is hydrogen bonded to Cl(-) (H.Cl). The Li(+) cation is coordinated to the five O atoms of 15C5 as well as the O atom from H(2)O, and the Cl(-) counteranion is isolated from Li(+) by two hydrogen bonds with one H atom each from two H(2)O molecules with H.Cl distances of 2.30(4) and 2.35(4) Å, respectively. A crystallographically imposed center of symmetry generates a dimer that resembles a 2:2 anion-paired encapsulate. Crystal data for 1: space group Pna2(1) (no. 33), a = 14.974(1) Å, b = 13.553(1) Å, c = 7.160(1) Å, V = 1453.0(2) Å(3), Z = 4. Crystal data for 2: space group P2(1)/n (no. 14), a = 10.353(1) Å, b = 7.9070(1) Å, c = 17.741 Å, beta = 100.50(1) degrees, V = 1427.9(2) Å(3), Z = 4.