Synthesis, spectroscopic and structural studies of 2,2,2-trifluoroethyl phosphorodiamidate complexes with tin(IV) chloride

The two octahedral complexes SnCl4 · 2(O)P(NR2)2OCH2CF3 (R = Me (1) or Et (2)) have been prepared from SnCl4 and the ligands (R2N)2P(O)OCH2CF3 in chloroform solution. Both adducts have been characterised by (31P and 119Sn) NMR, IR spectroscopy and elemental analysis. The NMR data show that the complexes exist as mixtures of cis and trans isomers in solution with the latter isomer being the predominant species. The structure of 1 has been determined by X-ray crystallography. Accordingly, the structure is centrosymmetric and the two ligands are bound trans to each other in the octahedral tin complex. DFT/B3LYP calculations show that trans configuration does indeed lead to the lowest energy species. Comparison of the structural, NMR and theoretical data of both complexes with those related to SnCl4 · 2L (L = (Me2N)3P(O) and (Me2N)2P(O)F) further supports the important effects of the nature of the substituents in the ligand on the stereochemistry of the complex formed.

Graphical abstractThe two octahedral complexes SnCl4 · 2(O)P(NR2)2OCH2CF3 (R = Me (1) or Et (2)) have been prepared and studied by a combination of experimental NMR and X-ray and theoretical DFT/B3LYP investigations.Figure optionsDownload full-size imageDownload as PowerPoint slide