Crown ether complexation of p-block metal halides: synthesis and structural characterisation of [InI2(dibenzo-24-crown-8)(H2O)][InI4], [(SnBr4)2(dibenzo-24-crown-8)]·MeCN, [(SbCl3)2(dibenzo-24-crown-8)]·MeCN, [(BiCl3)2(dibenzo-24-crown-8)]·MeCN and [(SbBr3)2(dibenzo-24-crown-8)

Abstract

The reactions of the large crown ether 6,7,9,10,12,13,20,21,23,24,26,27-dodecahydrodibenzo[b,n][1,4,7,10,13,16,19,22]octaoxycyclotetracosine (dibenzo-24-crown-8) with p-block metal halides have been studied, leading to the isolation and structural characterisation of [InI2(dibenzo-24-crown-8)(H2O)][InI4] (I), [(SnBr4)2(dibenzo-24-crown-8)]·MeCN (II), [(SbCl3)2(dibenzo-24-crown-8)] (III), [(BiCl3)2(dibenzo-24-crown-8)]·MeCN (IV) and [(SbBr3)2(dibenzo-24-crown-8)]·MeCN (V). Compound I was isolated as colourless block crystals; crystals are triclinic, space group P1̄, Z=2, R=0.0372. The structure consists of [InI2(dibenzo-24-crown-8)(H2O)]+ cations and [InI4]− anions. For the cation, the threaded near-linear InI2+ unit (In-I 2.6977(5), 2.6919(5) Å) is located off-centre within the cavity and is bonded to four ring oxygen atoms (In-Ocrown 2.344(4)–2.560(4) Å) and a single water molecule (In-Owater 2.271(4) Å). The latter forms intracavity hydrogen bonds of the type M-OH2⋯Ocrown to two more of the oxygen atoms of the crown (Owater⋯Ocrown 2.89, 2.94 Å). Compound II was isolated as orange block crystals; crystals are monoclinic, space group I2/m, Z=2, R=0.0391. The structure features the two metal centres in exocyclic locations each bound to two oxygens of the ring (Sn-Ocrown 2.262(3) Å). The metal geometry is distorted octahedral (Sn-Br 2.5235(7), 2.5187(6) Å). Compound III was isolated as colourless block crystals; crystals are monoclinic, space group C2/c, Z=4, R=0.0311. The two SbCl3 moieties (Sb-Cl 2.3807(8), 2.3874(8), 2.4015(9) Å) are coordinated to opposite sides of the crown which adopts a sigmoidal conformation to create two O5 donor cavities. Each Sb(III) centre is bound to five oxygens of the ring (Sb-Ocrown 2.852(2)–3.153(2) Å). Crystals of IV are monoclinic, space group C2/c, Z=4, R=0.0325. The structure is directly similar to that of III with two BiCl3 units (Bi-Cl 2.5034(12), 2.5054(13), 2.5389(12) Å) coordinated to opposite sides of the ring which exhibits a sigmoidal conformation. Each Bi(III) centre is bonded to five crown oxygen atoms (Bi-Ocrown 2.733(3)–3.221(4) Å). Compound V crystallises in the triclinic space group P1̄, Z=2, R=0.0693. The two SbBr3 groups are located on opposite sides of the ring (Sb-Br 2.5268(15), 2.5478(15), 2.5558(14) Å) and each one is bound to four of the ring oxygen atoms (Sb-Ocrown 2.893(7)–3.183(8) Å).