Surface organometallic complexes formation

Reaction of Organometallic Complexes with Oxide Supports the Controlled Formation of Surface Organometallic Complexes... 

The formation of a stable monobutyl species obtained at 50 °C is also further demonstrated by its hydrogenolysis at higher temperatures. Indeed, treatment under H2 of the grafted surface organometallic complex, Pts[SnBu]jy, at 300 °C for 4 h generates about one butane per Sn along with traces amounts of propane, ethane, and methane. 

New types of tin anchoring sites were created when both PSCs and CUPSCs were mildly oxidized to Oxidized Surface Organometallic Complex (OSOC), with general formula of -SUaRbOc. The addition of trace of oxygen led to the immediate formation of ethylene, i.e. surface chemistry involved in tin anchoring was altered. In this case as shown in Scheme 2 the lone pair of electrons of the... 

The decomposition of surface organometallic complexes formed in tin anchoring steps (see reactions (3) - (9)) was accomplished as a gas-solid reaction in the temperature range between 25-300 °C. The decomposition in a hydrogen atmosphere led to the formation of alloy-type bimetallic surface entities. More details on the decomposition of different surface organometallic complexes can be found elsewhere. These Sn-Pt catalysts will be referred as (H) type catalysts. 

Several rhodium-allyl complexes were immobilized on to solid supports. For example, the reaction of Rh( j -03115)3 with the surface hydroxyl groups of partially dehydroxylated silica led to the formation of the surface organometallic complex (=SiO)(=SiOX)Rh(77 -C3Hs)2 (where X is H or Si=), with the evolution of propene. ... 

Based upon analogies between surface and molecular coordination chemistry outlined in Table 1, we have recently set forth to investigate the interaction of surface-active and reversibly electroactive moieties with the noble-metal electrocatalysts Ru, Rh, Pd, Ir, Pt and Au. Our interest in this class of compounds is based on the fact that chemisorption-induced changes in their redox properties yield important information concerning the coordination/organometallic chemistry of the electrode surface. For example, alteration of the reversible redox potential brought about by the chemisorption process is a measure of the surface-complex formation constant of the oxidized state relative to the reduced form such behavior is expected to be dependent upon the electrode material. In this paper, we describe results obtained when iodide, hydroquinone (HQ), 2,5-dihydroxythiophenol (DHT), and 3,6-dihydroxypyridazine (DHPz), all reversibly electroactive... 

It was later found that stable organometallic compounds of transition metals exhibiting very low polymerization activity could be transformed into high-activity catalysts when deposited on silica, alumina, or silica-alumina.287-289 Interaction of surface hydroxyl groups with the organometallic compounds such as chromocenes, benzyl, and Tt-allyl complexes results in the formation of surface-bound organometallic complexes (41-43) 289-291... 

As already indicated in the discussion on formyl formation, the transition state on a metal surface may be closely related to that found in the organometallic complexes used in homogeneous catalysis. The p orbital stabilizing interactions have also been shown to play an important role in insertion reactions occurring in organic-metallic complexes [84,85]. It explains, for instance, the higher activa-... 

In contrast to groups 4 and 5 transition metal complexes supported on silica, the treatment by H2 of W surface organometallic derivatives, namely, [(=SiO)W( C Bu)(CH2 Bu)2] and [(=SiO)2W( C Bu)(CH2 Bu)], mainly lead to sintering (re-formation of silanols and detection of W particles by transmission electron microscopy (TEM)) and the hydride is obtained only in minute amounts. On the other hand, [(AlsO)W( C Bu)(CH2 Bu)2] reacts with H2 to give tungsten hydride species [(AlsO)2W(H) .] with no evidence of sintering, as evidenced by the presence of W-H and Al-H bands in the IR spectrum (Scheme 46). ... 

---