TY - CHAP
T1 - Noninnocent behavior of PCP and PCN pincer ligands of late metal complexes
AU - Poverenov, Elena
AU - Milstein, David
PY - 2013/1/1
Y1 - 2013/1/1
N2 - Pincer complexes are generally viewed as stable compounds in which the pincer ligand framework remains unchanged during stoichiometric and catalytic reactions. However, there are now several cases in which the pincer ligand itself undergoes transformations that result in extraordinary reactivity of the metal complex and formation of unusual species. In the current chapter, we review our work on noninnocent reactivity modes of various PCP and PCN-type pincer ligands of Rh, Ir, Ru, Os, Pd, and Pt. Participation of the arene ring in the reactivity of PCP type complexes has led to formation of unprecedented quinonoid complexes, including complexes in which the pincer ligand adopts structures of quinone methides, thio-quinone methides, xylylenes, methylene arenium, and oxo-arenium compounds. In addition, pincer systems can collapse and be regenerated under redox conditions, and reduction can lead to a ring-localized radical anion complex. The generation of C-H agostic arene PCP complexes has led to new insights regarding the C-H bond activation process, and the effect of CO ligands on it.
AB - Pincer complexes are generally viewed as stable compounds in which the pincer ligand framework remains unchanged during stoichiometric and catalytic reactions. However, there are now several cases in which the pincer ligand itself undergoes transformations that result in extraordinary reactivity of the metal complex and formation of unusual species. In the current chapter, we review our work on noninnocent reactivity modes of various PCP and PCN-type pincer ligands of Rh, Ir, Ru, Os, Pd, and Pt. Participation of the arene ring in the reactivity of PCP type complexes has led to formation of unprecedented quinonoid complexes, including complexes in which the pincer ligand adopts structures of quinone methides, thio-quinone methides, xylylenes, methylene arenium, and oxo-arenium compounds. In addition, pincer systems can collapse and be regenerated under redox conditions, and reduction can lead to a ring-localized radical anion complex. The generation of C-H agostic arene PCP complexes has led to new insights regarding the C-H bond activation process, and the effect of CO ligands on it.
KW - agnostic pincer complex
KW - late transition metals
KW - methylene arenium complex
KW - phenoxonium complex
KW - Pincer ligands
KW - quinone methide complex
KW - reactive intermediates
KW - thioquinone methide complex
KW - xylylene complex
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U2 - 10.1007/978-3-642-31081-2-2
DO - 10.1007/978-3-642-31081-2-2
M3 - Chapter
AN - SCOPUS:84868521387
SN - 9783642310805
T3 - Topics in Organometallic Chemistry
SP - 21
EP - 48
BT - Organometallic Pincer Chemistry
A2 - Koten, Gerard van
A2 - Milstein, David
ER -