Oxy- and thio-phosphorus acid derivatives of tin: XIII. Di- and triorganotin(IV) monothiophosphate esters

Abstract

Eleven di- and triorganotin(IV) O,O′-diorganomonothiophosphate esters, RnSn[OP(S)(OR′)2]4-n where n = 2, R = CH3, C2H5, n-C4H9, n-C8H17, C6H5 and R′ = CH3 and where R = C6H5 and R′ = C6H5 and where n = 3, R = CH3, n-C4H9, C6H5 and R′ = CH3 and where R = C6H5, C6H5CH2 and R′ = C6H5, are synthesized in high yield by the reaction of the corresponding organotin(IV) chlorides with the sodium salt of the R′ = CH3 acid and the triethylammonium salt of the R′ = CH3 acid and the triethylammonium salt of the R′ = C6H5 acid in ethanol. The products are colorless crystalline solids or oils, soluble in organic solvents. Vibrational spectroscopic band assignments can be made for the ν(P-O) (1220-1050 cm−1), ν(P-OR) (1000-900 cm−1), ν(P=S) (700-600 cm−1), ν(Sn-C) (600-500 cm−1), and ν(Sn-O) (500-400 cm−1).The tin-119m Mössbauer isomer shift (IS) values confirm tin as tin(IV), but the quadrupole splitting (QS) values fall into two groups with the tribenzyl- and di-n-octyltin derivatives exhibiting small magnitudes typical of four-coordination, with unidentate ligands. The other diorganotins exhibit very large QS values, corresponding to six-coordination with trans-R2Sn groups. From a point-charge model calculation, the dimethyltin group is linear, and the diphenyltin angles are 173.2 and 139.4° for (C6H5)2Sn[OP(S)(OR)2]2 where R = CH3 and C6H5, respectively. However, the observation of both νasym and νsym (Sn-C) in both the infrared and Raman spectra of the dimethyltin derivative rules out a strictly linear array. The strong Mössbauer spectra exhibited by the R2Sn[OP(S)(OCH3)2]2 derivatives at room temperature where R = CH3 and C2H5 suggest intermolecular association, and variable-temperature data for the R = C6H5 derivative yield a slope of dln A/dT = −0.972 × 10−2 K−1, reflecting a tightly-bound lattice as well, probably containing bridging ligands. No fragments of mass greater than the parent ion or containing more than one tin atom are seen in the mass spectra of any of the compounds studied, however. The triorganotins, other than the tribenzyl-derivative, exhibit large QS values signifying five-coordination, and the NMR |2J(119Sn-C-1H)| of 74.0 Hz for the trimethyltin derivative in solution is corroboratory. However, the negative tin-119 NMR chemical shift relative to tetramethyltin for the tri-n-butyltin derivative corresponds to four-coordination in solution. Bis(O,O′-diphenylthiophosphato)diphenyltin(IV) hydrolyzes on the benchtop or in wet ether to give the intermediate, dimeric hydrolysis product, [(C6H5)2SnOP(S)(OC6H5)2OH]2.