Bimetallic catalysts tungsten

Reaction of a reduced Philipps catalyst with Fischer-type molybdenum or tungsten carbene or carbyne complexes led to very active bimetallic, heterogeneous olefin metathesis catalysts. Surface metal ions might be involved in bonding interactions with the organometallic complex, possibly leading to heterometallic species on inorganic oxides. ... 

Seven-coordinate bimetallic compounds are also active unicomponent catalysts in the ring-opening metathesis polymerisation (ROMP) of cyclic olefins. The first step in this reaction is the coordination of olefin to metal. However, only in the reaction with a chelating ligand such as norbornadiene (NBD) was it possible to isolate and characterise the reaction product. In the reaction with NBD chloride bridge splitting in the binuclear compound of tungsten(II) by a diene molecule occurs very easily and monomeric seven-coordinate compounds are formed (Eq. 6) [48]. 

Heterogeneous, bimetallic metatheses catalysts are formed by reaction of Fischer type carbyne tungsten(0) or... 

Heterogeneous, bimetallic metathesis catalysts are formed by reactions of Fischer type carbyne tungsten or molybdenum complexes with the reduced Phillips catalyst, a suface chromium(II) compound on silica (14).(scheme 5). The bimetallic surface compounds can result from 2+1 cycloaddition reactions. Similar reactions are well known by the work of Stone (15). 

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