The recently studied set of (3-methoxypropyl)stannanes of general formula R_xSnCl_4–x [R = (CH₂)₃OCH₃, x = 4 (1), x = 3 (2), x = 2 (3) and x = 1 (4)] is extended with two new sets of (3-methoxypropyl)stannanes of general formula RPh_3–xSnCl_x [x = 0 (5), x = 1 (6) and x = 2 (7)] and RSn(S₂CNEt₂)_3–xCl_x [x = 0 (8), x = 1 (9) and x = 2 (10)]. The molecular structures of 6, 7, 9 and 10 in the solid state were determined by X-ray diffraction. In compounds 6 and 7, the 3-methoxypropyl ligand forms a C,O-chelate and the tin atom is coordinated as a distorted trigonal bipyramid with the oxygen and one chlorine atom in the axial positions. Compounds 9 and 10 are hexacoordinate with a distorted octahedral ligand arrangement. While the 3-methoxypropyl ligand in 10 also forms a C,O-chelate, the oxygen atom in 9 is not coordinated to the central tin atom. The structures in a non-coordinating (CDCl₃) and a coordinating solvent ([D₆]DMSO) were studied by multinuclear ¹H, ¹³C and ¹¹⁹Sn NMR spectroscopy. It is proposed that the structures found in the solid state are retained upon dissolution in CDCl₃. Compounds 5, 8 and 9 also preserve their structures in [D₆]DMSO. On the other hand, an equilibrium, in which one or more molecules of solvent enter the coordination sphere of the central tin atom and cleave the oxastannacycle, is established in [D₆]DMSO solutions of 6, 7 and 10. A comparison of the J coupling constants obtained from 1D ¹H,¹¹⁹Sn HMQC and 2D ¹H,¹¹⁹Sn J-HMBC spectra and the J coupling constants derived from conventional 1D ¹³C NMR spectra shows that the best indicator of the OSn donor–acceptor interaction in 3-methoxypropylstannanes is the ³J value. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)