title: PNP-Pincer-Type Phosphaalkene Complexes of Late Transition Metals.
abstract: This account summarizes our recent studies on PNP-pincer-type phosphaalkene complexes. Phosphaalkenes with a P=C bond possess an extremely low-lying π* orbital and have a marked tendency to engage in strong π back-bonding with transition metals. This particular ligand property provides PNP-pincer complexes with unique structures and reactivities. 2,6-Bis(phosphaethenyl)pyridine leads to the isolation of coordinatively unsaturated complexes of Fe(I) and Cu(I); the former adopts a trigonal monopyramidal configuration, whereas the latter has a strong affinity for PF6- and SbF6- as non-coordinating anions. Unsymmetrical PNP-pincer-type phosphaalkene complexes of Ir(I) bearing a dearomatized pyridine unit instantly cleave the N-H bond of NH3and the C-H bond of MeCN at room temperature. The dearomatized iridium complexes catalyze the dehydrative coupling of amines with alcohols to afford N-alkylated amines and imines in high yields.
authors.affiliation: International Research Center for Elements Science (IRCELS), Institute for Chemical Research Kyoto University, Uji, Kyoto, 611-0011, Japan. ozawa@scl.kyoto-u.ac.jp.
authors.forename: Fumiyuki
authors.initials: F
authors.lastname: Ozawa
authors.affiliation: Interdisciplinary Research Center for Catalytic Chemistry National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, 305-8565, Japan. yumiko-nakajima@aist.go.jp.
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Nakajima
keywords: N,P ligands; bond activation; homogeneous catalysis; phosphaalkenes; transition metals