Heterogeneous catalysis is still the industrial cornerstone in the production of basic chemicals, polymers, and in some instances fine chemicals. One of the key problems in developing new heterogeneous catalysts has been the low content of active sites coupled with their diversity, which makes their characterization very difficult and which often does not allow a rational understanding of their reactivity and selectivity. Even in cases where, using approaches such as surface organometallic chemistry (SOMC), well-defined complexes are prepared, a detailed structural characterization of the geometry of such surface species is extremely difficult.
In molecular chemistry the local geometries can be probed by NMR spectroscopy, for example, by measuring scalar coupling constants. So far coupling constants on surfaces could not be determined. Herein we demonstrate how J C,H coupling constants can be measured in solids by using twodimensional (2D) J-resolved spectroscopic methods, and how they are related to the local structure of the well-defined silica-supported rhenium complex 1. This complex was shown to be a highly active heterogeneous catalyst for the metathesis of a variety of olefins at room temperature. [1] In addition, two isomers can be obtained upon thermal or photochemical treatment (referred to as syn and anti, depending on the position of the tBu fragment on the carbene ligand relative to the metallocarbyne), which were both characterized by solid-ZUSCHRIFTEN