A triorganotin(IV) cocrystal with pyridinic phosphoramide: crystal structure and DFT calculations

Abstract

Herein, a two-component cocrystal [Ph3SnCl(4-PCAPh) 1] encompassing 4-PCAPh = N-isonicotinyl, N′,N″-bis(hexamethylenyl) phosphoric triamide and triphenyltin(IV) chloride in 1:1 stoichiometric ratio has been reported. Crystallographic information and theoretical calculations, mainly analysis based on the non-covalent interactions (NCI) visualization index, were pursued to generate a profound understanding of the structure-directing interactions in this cocrystal. Two crystallographically independent molecules are present for each component in the crystalline lattice, 1(A) and 1(B). Different conformational structures of 4-PCAPh primarily form centrosymmetric N–H⋯O hydrogen-bonded dimers in the crystal. Geometrical parameters around tin(IV) centers reveal that cocrystal components are interlinked through Sn⋯Npy semi-coordination. The formation of cocrystal and failure in achieving an adduct can be justified in terms of the steric bulk of phenyl groups along with π⋯π-stacking forces between components. The importance of non-covalent interactions in the stability of crystalline structure was elucidated by computing their binding energies using theoretical studies. QTAIM and NBO analyses data also justify the presence of two different Sn⋯N interactions, in agreement with crystal data and NCI-RDG analyses. The small HOMO–LUMO bandgap for Ph3SnCl(4-PCAPh) also signifies more reactivity for the cocrystal than 4-PCAPh.