Preparation, Structure, and Solid-State Reactivity of Lanthanum Propynoates

摘要

A comparative study of the complexes La_2(O_2CC≡CH)_6(H_2O)_4·2H_2O (1) and La_2(O_2CC≡CH)_6-(C_(10)H_8N_2)_2(H_2O)_2·4H_2O·2C_(10)H_8N_2 (2) was undertaken to assess the effect of introducing bulky ligands on the solid-state reactivity of metal propynoates. A solid-state polymerization reaction occurred when 1 was exposed to ~(60)Co γ-rays; complex 2 was found to be stable to ~(60)Co γ-irradiation. Complexes 1 and 2 have closely-related molecular structures and, as expected, rather different packing arrangements. The crystal structures of 1 (with infinite chains of short acetylene-acetylene contacts) and 2 (containing only a chain of only five short acetylene-acetylene contacts) are consistent with the observed reactivity patterns. The results provide useful insight into the planning of syntheses for radiation-sensitive materials. Crystal data: 1: monoclinic, space group P2_1/c, a = 11.126(3), b = 14.174(4), c = 8.851(3) A; β = 99.65(3)°; Z = 2; R = 0.027, R_w = 0.037 for 3674 data for which Ⅰ> 1.96σ-(Ⅰ). 2: triclinic, space group P1, a = 10.393(3), b = 13.022(4), c = 13.413(4) A; α = 116.90-(1); β = 101.03(1); γ = 103.82(1)°; Z = 1; R = 0.025, R_w = 0.024 for 4921 data for which F > 4σ(F).