TY - JOUR
T1 - Pyridine-derived N-heterocyclic carbenes
T2 - An experimental and theoretical evaluation of the bonding in and reactivity of selected normal and abnormal complexes of nickel(II) and palladium(II)
AU - Stander-Grobler, Elzet
AU - Schuster, Oliver
AU - Heydenrych, Greta
AU - Cronje, Stephanie
AU - Tosh, Evangeline
AU - Albrecht, Martin
AU - Frenking, Gernot
AU - Raubenheimer, Helgard G.
PY - 2010/11/22
Y1 - 2010/11/22
N2 - We report a thorough investigation of a series of isomeric complexes with the general formula trans-(pyridylidene)M(PPh3)2Cl (M = Pd, Ni). For the first time, a systematic comparison of normal, abnormal, and remote bonding modes is presented. X-ray structural and 13C NMR data indicate the importance of carbenoid mesomeric contributions in their compound class. The catalytic performance of the palladium complexes trans-(pyridylidene) Pd(PPh3)2Cl as precursors in Suzuki-Miyaura-type cross-coupling suggests a correlation of remote bonding with catalyst robustness and effectivity. When metal precursors M(PPh3)4 are reacted with 2,4-dichloropyridinium salts, preferential formation of remote carbene complexes occurs and indications are that electronic parameters rather than steric influences are responsible for the observed selectivity. Calculations at the BP86/TZ2P level of theory support interpretation of the results.
AB - We report a thorough investigation of a series of isomeric complexes with the general formula trans-(pyridylidene)M(PPh3)2Cl (M = Pd, Ni). For the first time, a systematic comparison of normal, abnormal, and remote bonding modes is presented. X-ray structural and 13C NMR data indicate the importance of carbenoid mesomeric contributions in their compound class. The catalytic performance of the palladium complexes trans-(pyridylidene) Pd(PPh3)2Cl as precursors in Suzuki-Miyaura-type cross-coupling suggests a correlation of remote bonding with catalyst robustness and effectivity. When metal precursors M(PPh3)4 are reacted with 2,4-dichloropyridinium salts, preferential formation of remote carbene complexes occurs and indications are that electronic parameters rather than steric influences are responsible for the observed selectivity. Calculations at the BP86/TZ2P level of theory support interpretation of the results.
UR - http://www.scopus.com/inward/record.url?scp=78649263223&partnerID=8YFLogxK
U2 - 10.1021/om100431u
DO - 10.1021/om100431u
M3 - 文章
AN - SCOPUS:78649263223
SN - 0276-7333
VL - 29
SP - 5821
EP - 5833
JO - Organometallics
JF - Organometallics
IS - 22
ER -