'Soft' Calixarenes–Structural Aspects of Calixarene Allyl Ethers and of Thiacalixarene Synthesis

Abstract

Syntheses and room-temperature single-crystal X-ray structure determinations are recorded for an array of p-t-butylcalix[n]arenes, n = 4 or 6, diversely functionalized at the phenolic oxygen atoms: the 1,3-diallyl 2,4-dimethyl ether for n = 4 (1), the hexaallyl ether for n = 6 (2), and the 1,3-dibenzyl 2,4-bis(dimethylthiocarbamoyl) derivative for n = 4 (3), with a view to establishing ligand baseline conformations for subsequent metal complexation studies, and for exploring any inclusion properties. Compound (1) is monoclinic, P2₁/c, a 16·751(9), b 20·772(7), c 27·91(1) Å, β 99·39(4)°, Z = 8, conventional R on |F| being 0·060 for N_o 4396 'observed' (I > 3σ(I )) reflections. Compound (2) is triclinic, P^-1, a 19·63(2), b 14·57(2), c 14·188(9) Å, α 107·84(8), β 93·26(7), γ 99·48(10)°, Z = 2, R 0·067 for N_o 7315. Compound (3), as its methanol monosolvate, is triclinic, P^-1, a 15·592(4), b 15·17(3), c 14·31(2) Å, α 88·8(1), β 64·3(1), γ 75·7(1)°, Z = 2, R 0·076 for N_o 3802. The conformation of (1) is similar to that previously established for an analogue in which two of the t-butyl groups were absent; the conformation of (2) is that of a flattened 1,2,3-alternate form, the asymmetric unit being a pair of half (centrosymmetric) dimers; the conformation of (3) is 1,3-alternate.