The 1:2 and 1:4 π-π type molecular adducts of bis(N-alkyl-2-oxy-4-(1-naphthoyloxy)benzaldiminato)copper(II) and 1,3,5-trinitrobenzene

Bis(N-alkyl-2-oxy-4-(1-napthoyloxy)benzaldiminato)copper(II) ([Cu(L^R)₂]; R = n-C₃H₇, n-C₄H₉, n-C₅H₁₁, n-C₆H₁₃) and 1,3,5-trinitrobenzene (tnb) formed the 1:2 and 1:4 π-π type molecular adducts depending on the chain length of the alkyl group, in which parent complexes with the shorter alkyl group (n-C₃H₇, n-C₄H₉) gave the 1:2 adducts, while those with the longer alkyl group (n-C₅H₁₁, n-C₆H₁₃) gave the 1:4 adducts. One of the 1:4 adducts [Cu(L^R)₂]·4ntb (R = n-C₆H₁₃) and the parent complex have been subjected to the single-crystal X-ray diffraction method. Both complexes crystallized in the triclinic space group P1 and each of the copper atoms is positioned at the inversion center. The crystal structure of the 1:4 adduct consists of two kinds of π-π type donor-acceptor stacking along the c-axis, where the first stacking is formed between the naphthalene moiety of the complex and one of two tnb molecules and the second stacking is formed between the benzene moiety and the other tnb molecule.