Evaluation of structural, spectroscopic, bonding and electronic properties of some organotin(IV)-phosphoric triamide complexes by using help of DFT, QTAIM and Hirshfeld surface investigations

Abstract

Different computational investigations by using help of DFT (density functional theory), QTAIM (quantum theory of atom in molecule) and HS (Hirshfeld surface) approaches are carried out to evaluate the various properties, especially Sn…O interactions, of some organotin(IV)-phosphoric triamide (OP is introduced as the phosphoric triamide ligand with a segment (O═)P[N]3) complexes. Among the most important results of this study is the absence of a net Sn-O bond between Sn(IV) center and O atom of P═O group (of OP ligand) in the segment Sn(CH3)2Cl2(OP)2, where no bond critical point (BCP) is found along the path connecting tin and oxygen atoms. However, a survey of other connectivities (such as Sn…C and C/Cl…O contacts) suggests a weak non-covalent interaction (with ionic in nature) for Sn…O(═P) in the studied complexes. DFT studies show that orientation of OP ligands around tin (trans or cis) is important for the strength of Sn…O interactions; so that a slightly higher strength is found in trans(OP)-form six-coordinate complexes of 1 – 3. Furthermore, a precise exploration of the intermolecular interactions by using Hirshfeld surface analysis reveals that the H…O/O…H (for 1 – 4) and H…Cl/Cl…H (for 1 – 5) contacts are favoured. A characteristic Sn….Cl contact with a high enrichment ratio is explored in five-coordinate complex 5. Finally, the presence of normal intermolecular interactions in the crystal structures of 3 and 4 is aligned with the lower chemical reactivities of these structures.