Assembly of hexa- and trinuclear monoorganostannoxanes: hemi-labile nature of intramolecular N→Sn coordination in RSnCl3 (R = 2-phenylazophenyl).

The reactions of RSnCl3 [R = 2-(phenylazo)phenyl] with phosphonic acids, RPO3H2 (R = t-Bu, C6H11) or (ArO)2PO2H (Ar = 4-NO2-C6H5O) in refluxing THF afforded hexatin cages, [(RSn)6(μ-OH)6(μ3-O)2(t-BuPO3)4]·5THF (1), [(RSn)6(μ-OH)6(μ3-O)2(C6H11PO3)4]·THF (2) and [(RSn)6(μ-OH)4(μ3-O)2{(NO2C6H4O)PO3}4]·THF (3), respectively. On the other hand, the reactions of RSnCl3 with 1,1,2,3,3-pentamethylene phosphinic acid [cycPO2H] or Ph2P(O)OH under similar reaction conditions afforded trinuclear O-capped clusters [(RSn)3(μ3-O) (μ2-OH)3 (μ-cycPO2)3] [cycPO2]·CH3CN·H2O (4) and [(RSn)3(μ3-O) (μ2-OH)3 (μ-Ph2PO2)3] [Ph2PO2]·CH3CN·CH2Cl2 (5) respectively. Molecular structures of 1-3 reveal that the intramolecular N→Sn coordination found in RSnCl3 is hemilabile; 1-3 do not contain such a feature and the tin atoms in these compounds are six coordinate, possessing a 1C, 5O coordination environment in a distorted octahedral geometry. The cage structures in 1-3, containing two trinuclear sub-units, are formed as a result of the coordination action of several ligands: 4 μ3-(η(1)η(1)η(1))[RPO3](2-), 2 μ3-O(2-) and 6 μ-OH. The molecular structures of 4-5 reveal them to be cationic trinuclear complexes where 3 tin and 4 oxygen atoms occupy the vertices of a distorted cube while one of the vertices is unoccupied. The molecular structures of 4-5 also reveal that the intramolecular N→Sn coordination present in RSnCl3 is absent in these compounds attesting to the hemilabile nature of this interaction.