Preparation, X-ray structures, and NMR spectra of elongated dihydrogen complexes with four- and five-coordinate tin centers

Abstract

Complex OsH3(SnPh2Cl){[è2-CH2dC(CH3)]PiPr2}(Pi- Pr3) (1) undergoes protonation-addition of benzoic acid to giVe the elongated dihydrogen deriVatiVe Os(SnPh2Cl)( 2-O2CPh)- (è2-H2)(PiPr3)2 (2). In solution the tin atom exchanges with the osmium on the chloride ligand by one of the oxygen atoms of the carboxylate group to afford OsCl{OC(Ph)OSnPh2}(è2- H2)(PiPr3)2 (3). Treatment of the latter with 1.0 equiV of benzoic acid leads to OsCl{OC(Ph)OSn( 2-O2CPh)Ph}(è2-H2)(PiPr3)2 (4). The elongated dihydrogen ligands of 2 and 3 show blocked rotation on the NMR time scale, whereas the hydrogen atoms undergo quantum exchange coupling. The X-ray structures of 3 and 4 are also reported.