Crystal structure determinations of {[(F 5 C 6 COO)Bu 2 Sn] 2 O} 2 and {[(4F-C 6 H 4 COO)-Bu 2 Sn] 2 O} 2 show that the structures are similar and feature central Bu 4 Sn 2 O 2 units with two Bu 2 Sn groups connected by bridging oxygen atoms. Each pair of exo- and endo-cyclic tin atoms is linked by an almost symmetrically bridging carboxylate group, with the two remaining groups attached to the exocyclic tin atom only. Crystals of {[(F 5 C 6 COO)Bu 2 Sn] 2 O) 2 are triclinic, space group P1, with unit cell dimensions a=12.425(3) A, b= 13.090(5) A, c=11.697(3) A, α=95.31(3)°, β= 93.28(2)°, γ=113.01(2)°, V=1734(1) A 3 , Z=1. Crystals of {[(4-F-C 6 H 4 COO)Bu 2 Sn] 2 O} 2 are also triclinic, space group P1, a=12.599(6) A, b= 25.359(4) A, c=11.480(4) A, α=91.44(3)°, β= 114.77(3)°, γ=97.43(3)°, V=3289(2) A 3 , Z=2. The structures were refined to final R=0.046, R w =0.046 for 4312 reflections with l≥3.0 σ(l) for {[(F 5 C 6 COO)Bu 2 Sn] 2 O} 2 and R = 0.061, R w = 0.068 for 4112 reflections with l≥3.0 σ(l) for {[(4-F-C 6 H 4 COO)Bu 2 Sn] 2 O} 2