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On the Stability of a POC sp3 OP‐Type Pincer Ligand in Nickel(II) Complexes
Author(s) -
Hao Jingjun,
MougangSoumé Berline,
Vabre Boris,
Zargarian Davit
Publication year - 2014
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201310386
Subject(s) - pincer movement , hydroamination , chemistry , nickel , ligand (biochemistry) , catalysis , medicinal chemistry , alkyl , pincer ligand , phosphinite , stereochemistry , decomposition , organic chemistry , biochemistry , receptor
We describe the results of a study on the stabilities of pincer‐type nickel complexes relevant to catalytic hydroalkoxylation and hydroamination of olefins, CC and CX couplings, and fluorination of alkyl halides. Complexes [(POC sp3 OP)NiX] are stable for X=OSiMe 3 , OMes (Mes=1,3,5‐Me 3 C 6 H 2 ), NPh 2 , and CCH, whereas the O( t Bu) and N(SiMe 3 ) 2 derivatives decompose readily. The phenylacetylide derivative transforms gradually into the zero‐valent species cis ‐[{κ P ,κ C ,κ C′ ‐( i Pr 2 POCH 2 CHCH 2 )}Ni{η 2 ,κ C ,κ C′ ‐( i Pr 2 P(O)CCPh)}]. Likewise, attempts to prepare [(POC sp3 OP)NiF] gave instead the zwitterionic trinuclear species [{(η 3 ‐allyl)Ni} 2 ‐{μ,κ P ,κ O ‐( i Pr 2 PO) 4 Ni}]. Characterization of these two complexes provides concrete examples of decomposition processes that can dismantle POC sp3 OP‐type pincer ligands by facile CO bond rupture. These results serve as a cautionary tale for the inherent structural fragility of pincer systems bearing phosphinite donor moieties, and provide guidelines on how to design more robust analogues.