Late transition metal-containing

The late transition metal-containing perovskites exhibit high electronic conductivities. In the materials which receive prime interest for oxygen delivery applications, the electronic contribution at high temperature of operation is usually predominant. The values for e.g., Lai rxCoi.yFey03 at 800°C in air... 

The dialkyl H-phosphonate molecule exhibits several different modes of coordination depending on the type of the corresponding metal or the Lewis acid [404]. A number of these complexes—especially in the case of the late transition metals—contain the tautomeric form of the starting dialkyl H-phosphonate, furnished presumably by a complex-ation-assisted equilibrium shift. 

The regio- and stereochemistries observed with isoprene indicated in Scheme 7 have been shown to be generally observable by using Pd catalysts, and these features are distinct from those observed with other late transition-metal-containing catalysts, as shown in Scheme... 

While essentially all the metal carbonyl complexes for group 4B contain terminal CO ligands, only recently have some bonafide doubly bridging carbonyl complexes been reported. However, these complexes are hetero-nuclear, since the carbonyl ligand bridges a zirconium atom with the metal center of a late transition metal. 

The first examples of highly active olefin polymerization catalysts based on late transition metals were nickel and palladium complexes containing bulky diimine ligands.310 312 For example, complex (120) was found to polymerize ethylene with an activity of ll,000gmmol h bar A range of PE materials with molecular weights up to 106 and... 

We seem to have been the first to appreciate that W(C0)2(n-C5Hs) (W,d1 2 3 4 5 6) is isolobal with CH (27), and to use this concept in designed syntheses of compounds with bonds between tungsten and other metals. We are hoping to extend the method to other systems containing LpM = CR groups, involving both early and late transition metals, e.g. 

Silver belongs to the late transition metals and, like gold, favors coordination to C=C triple bonds. A lot of silver-containing organometallic complexes, where silver-alkyne interactions assist the assembly of the complexes, are known. None of these complexes, however, was applied to efficient carbon-carbon bond formation in organic synthesis. 

Negishi previously reported that a wide variety of Lewis-acidic compounds catalyzed hydrozirconation of alkenes such as 1-decene 108 with /-BuZrCp2Cl.126 It was found that the reaction of 1-decene with 1.1 molar equiv. of TIB A, in the presence of 2-5 mol% of chlorine-containing late transition metals, led to the formation of 1-iododecane 110 after treatment of the product with iodine (Table 9). 

The annual production of various polymers can be measured only in billion tons of which polyolefins alone figure around 100 million tons per year. In addition to radical and ionic polymerization, a large part of this huge amount is manufactured by coordination polymerization technology. The most important Ziegler-Natta, chromium- and metallocene-based catalysts, however, contain early transition metals which are too oxophiUc to be used in aqueous media. Nevertheless, with the late transition metals there is some room for coordination polymerization in aqueous systems [1,2] and the number of studies published on this topic is steadily growing. 

Coordination polymerization of ethylene by late transition metals is a rather slow process especially when the catalyst is dissolved in water. In a study of the interaction of CH2=CH2 and [Ru(H20)6](tos)2 (tos = tosylate), both [Ru(CH2=CH2)(H20)5](tos)2 and [Ru(CH2=CH2)2(H20)4](tos)2 were isolated by evaporation of the aqueous phase which had been previously pressurized with 60 bar ethylene at room temperature for 6 and 18 hours, respectively. Longer reaction times (72 h) led to the formation of butenes with no further oligomerization. This aqueous catalytic dimerization was not selective, the product mixture contained Z-2-butene, E-2-butene and 1-butene in a 112.2122 ratio [3]. 

A major limitation of such Group IVB metallocene catalysts is that they are air- and moisture-sensitive and not tolerant to heteroatom-containing monomers. In the case of heteroatom-containing monomers the unbonded electron pairs on the heteroatom, such as oxygen, preferentially coordinate to the Lewis acid metal center in place of the carbon-carbon double bond. Some so-called middle and late transition metal organometallics are more tolerant to the presence of such heteroatoms and can be used as effective cocatalysts. These include some palladium, iron, cobalt, and nickel initiators. 

In general, amino-containing compounds are poor partners in CM due to their tendency to coordinate to the metal catalyst, even when late-transition metal systems are employed. To preserve catalyst activity, amino groups are therefore typically masked as cyanides, carbamates, amides, or phthalimides. In substrates where iV-coordination to the catalyst is less favored, such as with hindered /V-aryl-/V-allylamines, no protecting group is required. 

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