Diphosphinoazine rhodium(III) and iridium(III) octahedral complexes

• Published in: Inorganica Chimica Acta 2009, Vol.362 (1), p.208-216
• Main Authors: Pošta, Martin, Čermák, Jan, Vojtíšek, Pavel, Sýkora, Jan, Císařová, Ivana
• Format: Article
• Language: English
• Subjects: Diphosphinoazines; Hemilabile ligands; Iridium complexes; Polydentate ligands; Rhodium complexes
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/j.ica.2008.03.080

New octahedral Rh(III) and Ir(III) complexes of diphosphinoazines were prepared by two independent methods and characterized by NMR and X-ray diffraction. Complexes with both facial and meridional configuration were isolated, the preference for the particular configuration being probably controlled by steric reasons. Hemilability of a diphosphinoazine ligand in one of the complexes was experimentally observed by variable temperature NMR spectroscopy. Rhodium(III) and iridium(III) octahedral complexes of general formula [MCl 3{R 2PCH 2C(Bu t ) NN C(Bu t )CH 2PR 2}] (M = Rh, Ir; R = Ph, c-C 6H 11, Pr i , Bu t ; not all the combinations) were prepared either from the corresponding diphosphinoazines and RhCl 3 · 3H 2O or by the oxidation of previously reported bridging complexes [{MCl(1,2-η:5,6-η-CH CHCH 2CH 2CH CHCH 2CH 2)} 2{μ-R 2PCH 2C(Bu t ) NN C(Bu t )CH 2PR 2}] with chlorine-containing solvents. Depending on the steric properties of the ligands, complexes with facial or meridional configuration were obtained. Crystal and molecular structures of three facial and two meridional complexes were determined by X-ray diffraction. Hemilability of ligand in the complex fac-[RhCl 3{(C 6H 11) 2PCH 2C(Bu t ) NN C(Bu t )CH 2P(C 6H 11) 2}] consisting in reversible decoordination of the phosphine donor group in the six-membered ring was observed as the first step of isomerization between fac and mer isomers.