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How the Substitution Faraway from NHCs Affects the Structural Features and Catalytic Activity of Dicarbene Dipalladium Complexes
Author(s) -
Ge Kaiqi,
Cao Changsheng,
Liu Gang,
Li Yuling,
Zhang Juan,
Pang Guangsheng,
Shi Yanhui
Publication year - 2014
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201300344
Subject(s) - linker , chemistry , catalysis , styrene , yield (engineering) , regioselectivity , palladium , molecule , crystal structure , ethylene , stereochemistry , crystallography , medicinal chemistry , organic chemistry , materials science , copolymer , polymer , computer science , metallurgy , operating system
A series of [PdPyCl 2 ] 2 (di‐NHC) complexes were prepared (di‐NHC are two 1‐(2,6‐dimethylphenyl)imidazolidene molecules bridged by an aliphatic –(CH 2 ) n – linker ( n = 3, 4, 5, 6, and 10)). All complexes were fully characterized by NMR spectroscopy and elemental analyses. The crystal structures of four complexes ( n = 3, 4, 5 and 6) were determined by X‐ray diffraction. The influence of the distant methyl group on the structural features and catalytic activity with increasing of length of linker was investigated by comparing the results of these 2,6‐dimethylphenyl palladium complexes with those of their known mesityl analogues. X‐ray studies show the distant methyl substitution has big impact on the structure feature of the complexes with the shorter linker between two NHC (ethylene and propylene), but has a little or no effect on that of the complexes with longer linker (butylene and hexylene). Catalytic results of the arylation of styrene show that the remote substitute has big effect on the regioselectivity of the product in all complexes with shorter and longer linkers, but has a limited effect on the yield.