We report herein the synthesis of the N-methyl-N′N″-diorganoiminodiacetic acid diamides MeN[CH2C(O)N(R)H]2 [3: R = Me2N(CH2)2; 4: R = PhCH2; 5: R = Me3CCH2] and the novel tin(II) derivatives MeN[CH2C(O)N(R)]2Sn [6: R = Me2N(CH2)2; 7: R = PhCH2; 8: R = Me3CCH2]. The compounds were characterized by elemental analyses, 1H NMR spectroscopy (3–5), solid-state 13C and 119Sn NMR spectroscopy (8), and single-crystal X-ray diffraction analysis (5, 8). Compound 8 shows intramolecular N→Sn and intermolecular O→Sn interactions with distances of 2.370(2) and 2.406(2) Å, respectively, the latter indicating that 8 is a coordination polymer. DFT calculations revealed covalent Sn–NC(O) and coordinative N→Sn and C=O→Sn bonds. The wB97Xd functional, which takes into account dispersive interactions, was employed for a correct theoretical description of, in particular, the latter bond.