Assembly of tetranuclear triphenyltin-malonate and -chloride complexes: structural versatility, insights from multinuclear NMR spectroscopy, and single-crystal X-ray diffraction

Two tetranuclear triphenyltin-malonate complexes [Ph 3 Sn(H 2 O)(Ph 3 SnO 2 CCH 2 CO 2 )(SnPh 3 Cl) 2 ] ( 1a ) and [Ph 3 Sn(C 2 H 5 OH)(Ph 3 SnO 2 CCH 2 CO 2 )(SnPh 3 Cl) 2 ] ( 1b ), have been synthesized which crystallize together (in compound 1 ), which has been characterized by multinuclear NMR spectroscopy in solution and by single-crystal X-ray diffraction. The NMR spectra confirm the presence of triphenyltin fragments coordinated to a malonate ligand together with coordinated solvent molecules. The 119 Sn NMR spectrum exhibits two resonances, revealing the coexistence of tetrahedral and pentacoordinate tin environments in solution. Single-crystal X-ray diffraction shows that the compound 1 crystallizes in the monoclinic space group Cc with Z = 4 , a = 25.407(4), b = 12.2952(14), c = 43.157(5) Å, β = 98.057(3)° and V = 13,349(3) Å 3 , and contains the two crystallographically independent molecules ( 1a , 1b ) that differ in the nature of the coordinated solvent ligand (water versus ethanol). In both molecules, the doubly deprotonated malonate ligand adopts a tetradentate bridging mode linking four triphenyltin units into a discrete tetranuclear framework. The tin centers exhibit diverse coordination geometries, including tetrahedral SnPh 3 O and distorted trigonal bipyramidal environments (SnPh 3 ClO and SnPh 3 O 2 ) involving chloride, malonate oxygen atoms, and coordinated solvent molecules (water or ethanol). These solvent molecules are further engaged in O–H⋯Cl hydrogen bonding, generating supramolecular chains in the crystals. A survey of the Cambridge Structural Database indicates that such systems typically form polymeric networks; in contrast, the present structure remains molecular despite the tetradentate bridging mode. This highlights the structural versatility of malonate ligands and the key role of supramolecular interactions in controlling the dimensionality of organotin assemblies.