Seven novel R2SnIV-oxydiacetate (oda) and -iminodiacetate (ida) compounds of the form [R2Sn(oda)(H2O)](2) (R = Me, Bu-n, and Ph) (1-3)(1) [(R2SnCl)(2)(oda)(H2O)(2)](n) (R = Et, Bu-t, and Bu-t) (4-6), and [Me2Sn(ida)(MeOH)](2) (7) have been synthesized and characterized by IR, H-1, C-13, and Sn-119 NMR (solution), solid-state Sn-119 CPMAS NMR, and Sn-119m Mossbauer spectroscopy. The crystal structure Of [Me2Sn(oda)(H2O)](2), 1, shows it to be dinuclear (centrosymmetric), with two seven-coordinated tin atoms, bridged by one arm of the carboxylate group from each oda. By contrast, the crystal structure of [(Et2SnCl)(2)(oda)(H2O)(2)](n), 4, comprises a zigzag polymeric assembly containing a pair of different alternating subunits, {Et2SnCl(H2O)} and {Et2SnCl(H2O)(oda)}, which are connected by way of bridging oda carboxylates, thus giving seven-coordinate tin centers in both components. Finally, the structure of [Me2Sn(ida)(MeOH)]2, 7, also centrosymmetric dinuclear, is comprised of a pair of mononuclear units with seven-coordinate tin. The Sn-119 solid-state CPMAS NMR and Sn-119m Mossbauer suggest the presence of seven-coordinate Sn metal atoms in some derivatives and the existence of two different tin sites in the [(R2SnCl)(2)(oda)(H2O)(2)](n) compounds.