| Abstract |
Several new monophosphorylated 2,6-diaminopyridine ligands bearing PiPr(2) and PtBu2 units (PNNH2-iPr, PNNH2-tBu, PNNHMe-iPr, and PNNHEt-iPr) are prepared by treatment of the respective 2,6-diaminopyridines with the chlorophosphines PiPr(2)Cl and PtBu2Cl in the presence of a base. Treatment of anhydrous FeCl2 with 1 equiv of these afforded the tetracoordinated coordinatively unsaturated 14e(-) complexes [Fe(kappa(2) P,N-PNNH2-iPr)Cl-2] and [Fe(kappa(2) P,N-PNNH2-tBu)Cl-2], while with PNNHMe-iPr and PNNHEt-iPr a phosphine transfer reaction of a second PN ligand took place to yield the known PNP pincer complexes [Fe(kappa(3) P,N,P-PNPMe-iPr)Cl-2] and [Fe(kappa(3) P,N,P-PNPEt-iPr)Cl-2]. The four-coordinate complexes [Fe(kappa(2) P,N-PNNH2-iPr)Cl-2] and [Fe(kappa(2) P,N-PNNH2-tBu)Cl-2] did not react with CO and the formation of iron PNC pincer complexes was not observed. The reason for the reluctance to add CO was investigated in detail by DFT calculations. |
