Structures and relationship between the 119SnNMR chemical shifts and pKa of their parent acids in organotin (I∇) carboxylates

Ten di-n-butyltin(I∇) carboxylates (ⁿBu₂Sn-OCOR′)₂O]₂ and ⁿBu₂Sn(OCOR′)₂ (R′ = CCl₃, CHCl₂, CH₂Cl, PhCH = CH, and 2,2,3,3-tetramethylcyclopropyl) were synthesized and characterized by IR, ¹H, ¹³C, ¹¹⁹Sn NMR spectroscopy and elemental analysis. Together with other series of organotin(I∇) carboxylates, their structural features were discussed. The relationship between the ¹¹⁹Sn NMR chemical shifts in the organotin(I∇) carboxylates (ⁿBu₂SnOCOR′)₂O]₂, ⁿBu₂Sn(OCOR′)₂, ⁿBu₃SnOCOR′, Ph₃SnOCOR′ and the pK_a values of their parent acids R′COOH was studied. The results have shown that the log-δ(¹¹⁹Sn)] of the same series of carboxylates is linearly related to the pK_a of R′COOH. It seems that the better is the linearity between the log−δ(¹¹⁹Sn)] and the pK_a, the more analogous are the structures of the same series of carboxylates. © 1996 John Wiley & Sons, Inc.