Subtle C-H•••Hal (Hal = Cl, Br) Bonding as Predominant Synthon in the Assembly of Supramolecular Architectures Based on Luminescent Tin(IV) Complexes. Crystallography, Hirshfeld Surfaces, DFT Calculations, and Fluorescence

This report illustrates a successful C-H center dot center dot center dot Hal synthon-directed strategy to promote supramolecular aggregation of molecular luminescent complexes 1-6 into two- or three-dimensional supramolecular architectures. The tin complexes were prepared from the reaction of R(n)SnHal(4-n) compounds (R = n-Bu, Ph; Hal = Cl, Br; n = 0, 1) with (C5H4N)HC=N(C6H4)EH Schiff bases by either step-by-step synthesis [E = O (PyNO)] or multicomponent reaction [E = S (PyNS)]. Compounds 1-6 were characterized by IR, Raman, and H-1, C-13, and Sn-119 NMR spectroscopic studies as well as by X-ray diffraction studies. In addition, the fluorescent properties of all compounds were also investigated in the solid state and in THF solutions; the emission wavelengths ranged from orange to red (lambda(max) = 591-626 nm). Detailed structural characterization of the supramolecular organization of ordered solids revealed overall 2D and 3D interlinked networks driven by extensive C-H center dot center dot center dot Hal-Sn (Hal = Cl, Br) weak hydrogen bonds as primordial synthon and further stabilized by pi center dot center dot center dot pi stacking interactions as well as C-H center dot center dot center dot pi, C-H center dot center dot center dot O, or C-H center dot center dot center dot N contacts. Hirshfeld surface analysis and DFT calculations were used to asses additional insights into crystal structural features.