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New Concepts for Designing d 10 ‐M(L) n Catalysts: d Regime, s Regime and Intrinsic Bite‐Angle Flexibility
Author(s) -
Wolters Lando P.,
van Zeist WillemJan,
Bickelhaupt F. Matthias
Publication year - 2014
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201403237
Subject(s) - catalysis , steric effects , transition metal , chemistry , oxidative coupling of methane , bite angle , metal , selectivity , stereochemistry , physics , nanotechnology , crystallography , materials science , organic chemistry , denticity
Our aim is to understand the electronic and steric factors that determine the activity and selectivity of transition‐metal catalysts for cross‐coupling reactions. To this end, we have used the activation strain model to quantum‐chemically analyze the activity of catalyst complexes d 10 ‐M(L) n toward methane CH oxidative addition. We studied the effect of varying the metal center M along the nine d 10 metal centers of Groups 9, 10, and 11 (M=Co − , Rh − , Ir − , Ni, Pd, Pt, Cu + , Ag + , Au + ), and, for completeness, included variation from uncoordinated to mono‐ to bisligated systems ( n =0, 1, 2), for the ligands L=NH 3 , PH 3 , and CO. Three concepts emerge from our activation strain analyses: 1) bite‐angle flexibility, 2) d‐regime catalysts, and 3) s‐regime catalysts. These concepts reveal new ways of tuning a catalyst’s activity. Interestingly, the flexibility of a catalyst complex, that is, its ability to adopt a bent L‐M‐L geometry, is shown to be decisive for its activity, not the bite angle as such. Furthermore, the effect of ligands on the catalyst’s activity is totally different, sometimes even opposite, depending on the electronic regime (d or s) of the d 10 ‐M(L) n complex. Our findings therefore constitute new tools for a more rational design of catalysts.