Phosphonate ligands, [RPO₃]^2-, are extremely versatile in the assembly of multi-tin and multi-copper architectures. We have used organostannoxane cores for supporting multi-ferrocene and multi-porphyrin peripheries. The copper-metalated multi-porphyrin compound is an excellent reagent for facile cleavage of DNA, even in the absence of a co-oxidant. Reaction oft-BuPO₃H₂ with Cu(C10₄)₂. 6H₂O in the presence of 2-pyridylpyrazole (2-Pypz) leads to the synthesis of a decanuclear copper (II) assembly.

Optically active Lewis acids and Lewis pairs were synthesized and characterized by multinuclear NMR, UV/Vis spectroscopy and elemental analysis. Optical rotation measurements were carried out and the absolute configuration of the new chiral molecules confirmed by single crystal X-ray diffraction.

The interaction of a Lewis acid with a Lewis base results in the formation of a Lewis acid–base adduct. Understanding Lewis acids and bases is central to conceptualizing chemical interactions and constitutes a major portion of metal–ligand chemistry. Sterically encumbered/constrained Lewis pairs cannot form acid–base adducts, but such ‘Frustrated Lewis Pairs’ (FLPs), with their unquenched electronic demands can be elegantly used to simultaneously react with a third species, resulting in unusual reactivity of small molecules. Such unusual reactions, explored only in the last few years, have found several applications, e.g., heterolytic splitting of H₂, activation of small molecules (CO₂, N₂O, etc.). FLPs have opened new opportunities in synthetic chemistry, covering organic, main group as well as transition metal chemistry. The design strategies adopted for FLP systems and their unique reactivity are discussed here.

The reactions of p-diphenylphosphinobenzoic acid (LCOOH) with various organotin precursors have been carried out. Accordingly, the reaction of [n-BuSn(O)(OH]_n with LCOOH afforded the hexameric compound, [n-BuSn(O)O₂C–C₆H₄–p-PPh₂]₆(1). On the other hand, the reaction of LCOOH with [n-Bu₂SnO]_n gave the tetrameric compound [{n-Bu₂SnO₂C–C₆H₄–p-PPh₂}₂O]₂ (2). The 1-D coordination polymers [R₃SnO₂C–C₆H₄–p-P(O) Ph₂]_n,[ R=n-Bu (3), R=Ph (4)] were prepared in the reaction of [n-Bu₃Sn]₂O or [Ph₃Sn]₂O with LCOOH. The compounds 1–4 were structurally characterized by multinuclear NMR spectroscopic and single crystal X-ray diffraction studies