Sulphur(IV) compounds as ligands

Synthesis, Structure, and α-Elimination Chemistry of Hafnocene Triarylstannyl Complexes

“…Trimethylsilyl chloride (Gelest or Aldrich) was distilled prior to use. The compounds Hf(NMe 2 ) 4 , Me 2 C(C 5 H 5 ) 2 , Ph 3 SnH, PhLi, LiNMe 2 (from Li 0 and excess HNMe 2 ; isolated by evaporating excess HNMe 2 ), CpCp*Hf(Me)OTf ( 6 ),4a NaOMe, (THF) 3.5 LiSnPh 3 , , CpCp*Hf(H)Cl, and ClSn( p -FC 6 H 4 ) 3 were prepared according to literature procedures. The compounds CpCp*Hf(H)OMe and CpCp*Hf(H)NMe 2 were prepared by the reaction of 1 equiv of NaOMe or LiNMe 2 , respectively, with CpCp*Hf(H)Cl in THF at room temperature for 12 h. These species could not be isolated in pure form and were used as prepared.…”

“…CpCp*Hf[Sn(p-FC6H4)3]Cl (19). HSn(p-FC6H4)3 (0.175 g, 0.432 mmol) and CpCp*Hf(H)Cl (0.179 g, 0.431 mmol) were added to a Teflon-sealable Schlenk flask, and THF (10 mL) was vacuum transferred onto the solids.…”

“…13 C{ 1 H} NMR: δ 13.0, 112.1, 116.0, 121.2, 139.9, 146.2, 163.9. 19 (20). HSn[(CF3)C6H4]3 (0.263 g, 0.474 mmol) and CpCp*Hf(H)Cl (0.200 g, 0.482 mmol) were added to a Teflon-sealable Schlenk flask, and THF (10 mL) was vacuum transferred onto the solids.…”

“…material during synthetic manipulations. The new stannyl complexes are yellow in the solid state and in solution and give rise to 119 Sn NMR resonances of δ 120.9 (18), 116.5 (19), and 106.4 (20). The pattern of increasingly upfield 119 Sn NMR shifts is consistent with a decrease in electron density at Sn in going from 18 to 19 to 20.…”

“…To investigate the influence of electronic inductive effects on the rate of R-elimination, kinetic studies of the decompositions of CpCp*Hf(SnPh 3 )Cl (4), CpCp*Hf[Sn(p-(OMe)C 6 H 4 ) 3 ]-Cl (18), CpCp*Hf[Sn(p-FC 6 H 4 ) 3 ]Cl (19) constructed from these data (Figure 3) represents a linear correlation with a negative slope (F ) -2.13). The magnitude of this F value indicates that there is a significant electronic effect on the rate of decomposition, and the negative sign implies that electron donor groups promote the R-elimination process.…”