Element-element bonds. VIII. Synthesis, molecular and crystal structure of dibromo(2,4,6-trimethylphenyl)bismuthane

Article abstract of DOI:10.1002/zaac.199762301148

Dichloro-(1) und dibromo(2,4,6-trimethylphenyl)bismuthane (2) are obtained in relatively high yields from metathesis reactions of the corresponding bismuth(III) halides with tris(2,4,6-trimethylphenyl)bismuthane. An X-ray structure determination of the dibromo derivative 2 (monoclinic, P2₁/c; a = 896.2(2); b = 1531.9(3); c = 1713.3(3) pm; β = 94.31(3)° at -100 ± 3 °C; Z = 8 molecules; R = 0.059) shows two crystallographically independent molecules to build up a zigzag chain via strong Bi-Br··Bi bridges (Bi-Br 282 and 281; Br··Bi 302 and 302 pm) and relatively weak n⁶-arene··Bi interactions (mean values Bi··C 348 and 359 pm); for sterical reasons one bromo substituent of each molecule is not involved in coordinative bonding (Bi-Br 262 and 261 pm). To allow a better comparison of Bi-C_ipso bond lengths and arene··Bi contacts, relevant values of a greater number of related compounds have been compiled; for some of these examples arene··Bi interactions had not been reported before. Ir and Raman bands below 350 cm^-1 are assigned to stretching frequencies of the BiCl₂ (1) and BiBr₂ (2) fragments, respectively. Keywords: Dichloro(2,4,6-trimethylphenyl)bismuthane: dibromo(2,4,6-trimethylphenyl)bismuthane; crystal structure; Bi-Br··Bi bridges: n⁶-arene··Bi contacts; ir and Raman data.