Coordination compounds insertion

Starting from 63, the carbonylation may proceed via coordination and insertion of CO into the vinyl-C-Pd bond to provide an a,P-unsaturated acyl complex. This complex reacts with (ArY) 2, and subsequently the C-Y bond is formed by reductive elimination to give 64 (Scheme 7-14). Because the compound 64 could be directly converted into the corresponding enal 65 by the Pd-catalyzed reduction with BujSnH, this sequence is synthetically equivalent to the regio- and stereoselective thioformy-lation and selenoformylation of alkynes (Eq. 7.49) [53, 54]. 

A typical multilayer thin film OLED is made up of several active layers sandwiched between a cathode (often Mg/Ag) and an indium-doped tin oxide (ITO) glass anode. The cathode is covered by the electron transport layer which may be A1Q3. An emitting layer, doped with a fluorescent dye (which can be A1Q3 itself or some other coordination compound), is added, followed by the hole transport layer which is typically a-napthylphenylbiphenyl amine. An additional layer, copper phthalocyanine is often inserted between the hole transport layer and the ITO electrode to facilitate hole injection. 

More typical of coordination compounds are the following insertion reactions ... 

Incorporation of CO into an organic substrate usually occurs by insertion of CO into a C-metal bond. The requisite Cl-metal bond is formed by oxidative addition of a Pd(0) species into the Cl-Br bond, the normal first step upon combining a Pd(0) compound and an aryl halide. Coordination and insertion of CO follows. Addition of N to the carbonyl and loss of Pd(0) gives an iminium ion, which is trapped by EtOH to give the product. 

This reaction is a variation of the hydroformylation reaction. Transmetallation of Rh(I)(acac) with the alkylmercury(I) compound gives ClHg(acac) and an alkylrhodium(I) compound. Oxidative addition of H2 gives a Rh(III) compound, and coordination and insertion of CO gives the acylrhodium(IH) compound. Reductive elimination then gives the product and regenerates Rh(I) — but as a Rh-H, not as Rh(acac). 

M-C as propagating species, 4, 1008 monomer coordination and insertion reactions, 4, 1010 monomer insertion regio- and stereochemistry, 4, 1015 overview, 4, 1005-1166 regioirregular insertions, 4, 1023 stereocontrol mechanism, 4, 1018 stereocontrol symmetry rules, 4, 1020 stereoregular polymers, 4, 1016 in Ru-Os heterodinuclear compounds, 6, 1046 in Ru-Os mixed-metal clusters, 6, 1064 semiconductor growth, conventional precursors, 12, 2 with silicon, 3, 514... 

Titanium compounds with MAO or borate as co-catalysts effectively produce syndiotactic polystyrene from styrene monomer. The design of high-performance catalyst systems is now well demonstrated. The basic structure of the active site, the mechanism of coordination and insertion and the kinetics are also now well understood for this new polymerization. 

In contrast to CHEC-II(1996) where only rings which have relatively strong cr-bonds between adjacent atoms were reviewed, syntheses of heterocyclic complexes are also be described in this chapter. The chemistry of such chelates or coordination compounds is very interesting as the carbon-metal bond is labile and subject to various reactions such as insertion, protonation, or substitution. However, even though the synthesis of these intramolecular complexes is described in Section 4.19.9, their physical properties are not reported in this chapter. As the cyclic complex is in equilibrium with its open-chain form, the structural properties of such compounds may not be indicative of the heterocycle ring at all. 

Accordingly, a broadening of MWD should be possible only by creating inhomogeneity in the active centre valences so as to promote different capabilities of monomer coordination and insertion and, thus, different propagation constants. The correspondence between narrow MWD and a unique oxidation state of the transition metal has been also pointed out by Christman for the ethylene polymerization with vanadium compounds-aluminum alkyls homogeneous systems. In this case, addition of a promoter causes re-oxidation of the deactivated sites (V") to the same identical initial ones (V "). 

Mono-diene complexes of zirconocene and hafnocene have been prepared by two methods [129-131 ], viz the photochemical reaction of diphenylzirconocene in the presence of diene and the reaction of metallocene dichlorides with diene magnesium adduct. The structures and reactivity of s-cis-dicm complexes indicate that the metal-lacyclopentene (B) is the preferred canonical form. Complexes of the type Cp2Zr(j-/ra/25-1,3-diene), have been prepared they were the first examples of this mode of coordination (C). Insertion of unsaturated compounds into a diene coordinated to zirconocene results in regioselective C—C bond formation [132-136]. 

A detailed mechanism of asymmetric hydrovinylation is discussed in order to explain the pathways of the asymmetric induction4- 51314. The 7t-allylnickel complex, as the catalyst precursor, is activated by phosphanes and ethylaluminum chloride and reacts with an olefin to give a catalytically active nickel hydride-olefin complex. The olefin then inserts into the metal hydride bond and after coordination and insertion of ethene a new alkylnickel compound is... 

One of the important types of reactions exhibited by coordination compounds is that known as an insertion reaction, in which an entering ligand is placed between the metal ion and a ligand already bound to it. A general form of this reaction can be shown as... 

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