Multiple Melting Behaviour in Square-planar <i>trans</i>-Bis-(1-p-n-alkylphenylbutane-1, 3-dionato)-copper (II)—The Effect of Alkyl Chain Length

Abstract

Abstract The title complexes having different n-alkyl groups from methyl to dodecyl have synthesized All these complexes exhibit solid polymorphism. The number of polymorphs depends on the length of the alkyl chain: two for n (the number of carbon atoms) = 0 ∼ 2, three for n = 3 ∼ 5 and 12, and four for n = 6 ∼ 11, respectively. Each polymorphic form except those with the highest m.p.s. exhibits multiple melting behaviour: double melting for n = 0 ∼ 5,8, and 12, and triple melting for n = 6 ∼ 11 except 8. The m.p.s. of the complexes with alkyl groups of odd carbon atoms are higher than those with even atoms, while the respective ligand solids show the opposite even-odd effect in their m.p.s.