Active metal pairs, comparison

Comparison of Active Metal Pairs. The catalysts were evaluated at a temperature of 780°-850°F at a 2000°-2800°F pressure with a space velocity of 0.5 vol/vol/hr. The range of product distribution from this evaluation is summarized in Table IV. The quality of liquid product as defined by gravity, and by residuum (975°F +), hydrogen, nitrogen, sulfur, and oxygen contents, and by carbon on spent catalysts is presented... 

For both of these complexes the lone-pair electrons are not stereochemically active with respect to the polyhedral coordination, but stabilize the 6s and 5s level, respectively (inert pair effect). The interactions between metals and arenes are rather weak but significantly influence the coordination sphere in comparison to BiCl3 or SbCl3. 

We outline all the different bonding types that are essential for most chemical bond descriptions on metal surfaces. First, we discuss some general aspects of chemical bonding. In particular, in comparison to the delocalized s- or p-electrons, we emphasize the uniqueness of the more localized d-electrons in transition metals in the formation of the chemical bond. Most of the active catalysts are transition metals where -electrons play a major role and most adsorbates interact with the metal substrate via covalent bonding, i.e., electron-pair sharing involving mainly substrate -electrons. 

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