Synthesis, structures and preliminary biological screening of bis(diphenyl)chlorotin complexes and adducts: Ph2ClSn–CH2–R–CH2–SnClPh2, R = p-C6H4, CH2CH2

The reaction between ClCH2–R–CH2Cl, R = p-C6H4, and [Ph3Sn]−Li+ yields Ph3Sn–CH2–R–CH2–SnPh3 (1) in high yield. The related known compound R = CH2CH2 (1a) is synthesized by the reaction of the di-Grignard reagent BrMg(CH2)4MgBr with two equivalents of Ph3SnCl. Cleavage of a single Sn–Ph group at each tin centre of both compounds using HCl/Et2O yields the corresponding bis-chlorostannanes Ph2ClSn–CH2–R–CH2–SnClPh2, R = (CH2)4 (2) and R = C6H4 (3), respectively. Compounds 1, 2 and 3 are crystalline solid materials and their single crystal X-ray structures are reported. In the solid state both 2 and 3 form self-assembled ladder structures involving alternating intermolecular Cl–Sn⋯Cl and Cl⋯Sn–Cl bonded chains at both ends of the distannanes with 5-coordinate tin atoms. Recrystallization of 3 from CH2Cl2 in the presence of DMF yields the bis-DMF adduct (4) in which no self-assembled structures were noted. Evaluation of the chlorostannanes 2 and 3 against a suite of bacteria, Staphylococcus aureus, Escherichia coli and Photobacterium phosphoreum is reported and compared to the related mono-chlorostannanes Ph2(CH3)SnCl and Ph2(PhCH2)SnCl.