Di-and triorganotin(IV) derivatives of 2-benzoylbenzoic acid

Abstract Six triorganotin(IV) 2-benzoylbenzoates, 2-C 6 H 5 C(O)C 6 H 4 CO 2 SnR 3 , where R = CH 3 , C 2 H 5 , n-C 3 H 7 , n-C 4 H 9 , c-C 6 H 11 and C 6 H 5 , two 2-benzoyl-3,4,5,6-tetrachlorobenzoates, 2-C 6 H 5 C(O)C 6 Cl 4 CO 2 SnR 3 , where R = CH 3 and C 6 H 5 and two di-organotin(IV) bis-2-benzoylbenzoates, [C 6 H 5 C(O)C 6 H 4 CO 2 ] 2 SnR 2 , where R = CH 3 and C 6 H 5 , are prepared by metathesis between the organotin(IV) chloride and the sodium salt of the acid in ethanol, by azeotropically distilling water from benzene solutions of the bis-triorganotin(IV) oxide and the parent acid, or from tiorganotin(IV) hydroxide and the parent acid. The products are solids, and, except for the trimethyltin(IV) derivatives, are soluble in common organic solvents. Other Group IV ester derivatives of 2-benzoylbenzoic acid, 2-C 6 H 5 C(O)C 6 H 4 CO 2 MR 3 (MR 3 = Si(CH 3 ) 3 , Ge(C 2 H 5 ) 3 and Pb(C 6 H 5 ) 3 ), were also synthesized. 119m Sn Mossbauer isomer shift ( IS ) values confirm the tin(IV) oxidation states and the ruadrupole splittings ( QS ) (3.04–3.54 mm s −1 ) and ϱ ( QS/IS ) values (2.16–2.70) specify higher than four-coordination at tin in the solid state. From the QS values of the diorganotin(IV) derivatives a point-charge model is used to calculate the carbon-tin-carbon angles. The magnitudes of these angles show that these derivatives adopt a trans -configuration in the solid, and that the triorganotin(IV) derivatives have equatorial-R 3 Sn groups which are approximately planar. Absence of a ν asym (SnC) mode in the infrared and a ν sym (SnC) mode in the Raman specifies the planitary of the (CH 3 ) 3 Sn group on its solid derivative, but not in solution. Both bands appear for the (CH 3 ) 2 Sn derivative, ruling out a strictly linear array. The ketonic and carboxylate carbon-oxygen stretching frequencies are assigned at ca. 1650 and 1600 cm −1 , respectively, and it is concluded that the ketone group is not coordinated to the tin atom. The high values for the carbonyl stretching frequencies of the organosiyl-and germyl derivatives reflect four-coordination. NMR coupling constants, | 2 J ( 119 SnC 1 H|, reflect than four-coordination for the tri and dimethyltin(IV) derivatives in solution. 119 Sn NMR chemical shifts are to lower field than tetramethyltin for the aliphatic derivatives, reflecting low coordination, but not for the triphenyl- and diorganotin(IV) derivatives. Only one resonance is observed, so the open and lactol forms, if both are present, must be in rapid equilibrium. Carbon-13 resonance for the keto- and carboxylate carbons of the organotin derivatives resemble those of the open and not the lactol forms of the parent materials. No ditin or other fragments characteristics of the oligomer are seen in the mass spectrum at 70 eV. The evidence specifies an associated solid with bridging carboxylate groups from the open-form of 2-benzoylbenzoate in which the ketonic carbonyl group is not involved in coordination to the tin atom. The triorganotin(IV) derivatives contain equatorial-R 3 Sn groups, and the diorganotin(IV) derivatives contain trans -R 2 Sn groups.