Reactions of 5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoic acids (LHH', where the aryl group is an R-substituted Ph ring such that for L1HH': X = H; L2HH': X=2'-OCH3; L3HH': X = 3'-CH3; L4HH': X = 4'-CH3; L5HH':X = 4'-Cl) with nOct2SnO in 2:1 and 1:1 molar ratios have been investigated. Two types of complexes, nOct2Sn(LH)2 and {[nOct2Sn(LH)]2O}2, were isolated and they have been characterized by 1H, 13C, 119Sn NMR, ESI-MS, IR and 119mSn Moessbauer spectroscopic techniques in combination with elemental analyses. The crystal structures of nOct2Sn(L1H)2 (1), {[nOct2Sn(L2H)]2O}2 (3) and {[nOct2Sn(L3H)]2O}2(4) were detd. The mononuclear complex 1 was found to adopt a skew-trapezoidal bipyramidal arrangement around the tin atom while 3 and 4 are centrosym. tetranuclear bis(dicarboxylatotetrabutyldistannoxane) complexes contg. a planar Sn4O2 core in which two micro 3-oxo O-atoms connect an Sn2O2 ring to two exocyclic Sn-atoms. The soln. structures were confirmed by 119Sn NMR spectroscopy by observing one tin resonance in compd. 1 and two tin resonances in {[nOct2Sn(L5H)]2O}2 (5). {[nOct2Sn(L2H)]2O}2 (3) and {[nOct2Sn(L3H)]2O}2 (4) undergo very complex exchange processes in deuteriochloroform soln., which has been confirmed by variable temp. 1H NMR spectroscopy. The cleavage of the most labile bond in the mol. was studied by ESI mass spectrometry. [on SciFinder (R)]