Metal complexes of ditopic dithiophosphonate ligands built on a naphthalenediimide core

Ditopic ligands consisting of two dithiophosphonate donor groups attached to a 1,4,5,8-naphthalenediimide core through ether spacers of different length have been synthesized and characterized. The NDI[(CH2CH2O)n(An)PS2NH4]2 ligands (n = 1: 1a-[NH4]2; n = 2: 1b-[NH4]2; NDI = naphthalenediimide; An = anisole) react with Ph3SnCl and (Ph3P)2CuNO3 in a 1:2 ratio to yield bimetallic complexes (1a-[SnPh3]2 and 1a-[Cu(PPh3)2]2 for n = 1, and 1b-[SnPh3]2 and 1b-[Cu(PPh3)2]2 for n = 2), and with Ph2SnCl2 in a 1:1 ratio to form bimetallic ({1a-[SnPh2]}2) and monometallic (1b-[SnPh2]) macrocycles. Structural characterization of these compounds revealed monodentate and anisobidentate coordination modes of the dithiophosphonate group, as well as the presence of metal-sulfur secondary bonds. While the ditopic nature of the ligand does not have an influence over the coordination behavior of the individual –PS2 groups, the length of the naphthalenediimide-dithiophosphonate linker lead to different solid-state supramolecular architectures. Cooperative π–π stacking and C–H⋯π interactions organize the supramolecular structures of these complexes, generating two-dimensional sheets (in the case of “short-arm” ligand: 1a-[SnPh3]2 and 1a-[Cu(PPh3)2]2) and mono-dimensional chains (in the case of “long-arm” ligand: 1b-[SnPh3]2). In the case of {1a-[SnPh2]}2 and 1b-[SnPh2] metallacycles, π–π stacking interactions between NDI central moieties produce infinite π–π stacked chains and discrete dimers, respectively.