Transition Metal Complex Formation

The ability of transition metal ions, and especially chromium (as Cr3+), to form very stable metal complexes may be used to produce dyeings on protein fibres with superior fastness properties, especially towards washing and light. The chemistry of transition metal complex formation with azo dyes is discussed in some detail in Chapter 3. There are two application classes of dyes in which this feature is utilised, mordant dyes and premetallised dyes, which differ significantly in application technology but involve similar chemistry. 

Mono-functionalization of Cyg affords, preferrably, C(l)-C(2) adducts (type a) (Figure 13.3). In some cases, for example, upon nucleophilic cyclopropanations they even represent the exclusively formed monoadducts [1-3,17]. Typical examples of addition reactions that afford monoadducts are epoxidations [18,19], osmylation [9], transition metal complex formations [20, 21], hydrogenation [13, 22], many cycloadditions [1, 2] and additions of nucleophiles [23]. For the formation and the chemical transformation of azahomo[70]fullerenes see also Chapter 12 (Schemes 12.4 and 12.5). 

Transition Metal Complex Formation Perhaps one of the earliest applications of the pressure variable to confirm reaction mechanism involved examining... 

In the case of transition metal complex formation reactions, model systems are established and the patterns of reactivity can be discussed in terms of model systems. For example, cobalt(III) and platinum(II) do serve as paradigm for octahedral and square planar... 

The electronic structure of SO2 has been the subject of several theoretical studies which have provided a basis for interpretations of UV and photoelectron spectroscopic measurements These will not be reviewed in detail here since they all agree on those features which are important for a qualitative understanding of transition metal complex formation. The ground state configuration obtained from the extended Hiickel approach, for example, is (Iai) (lb2) (2ai) (lbi) (3ai) (2b2) (la2) (3b2) (4ai) (2bi) (4b2) (5ai) using 2 s, 2 p oxygen orbitals and 3 s, 3 p sulfur orbitals as a basis. The salient features from the M-SO2 bonding standpoint are the HOMO (4ai) and the LUMO (2bi), depicted in Fig. 2. These two orbitals can be described qualitatively as follows ... 

Fig. 9. Bis-adducts of C70 with chiral functionalization patterns, resulting from [2 + 2]cyclo-addition of alkynes and from transition metal complex formation...

Corey JY, Braddock-Wilking J (1999) Reactions of hydrosilanes with transition-metal complexes formation of stable transition-metal silyl compounds. Chem Rev 99 175-292... 

Liotta D, Li Y, inventors Emory University, assignee. Preparation of synthetic nucleosides via Tr-allyl transition metal complex formation. WO 2009/021114 Al. 2007 Aug 7. 

Silylene-based pincer ligands offer exciting reactivities in terms of transition metal complex formation and their applications in catalytic systems. The pincer complex [SiCSi)Ni(II) can be synthesized by oxidative addition of C—H bond of the corresponding [SiC(H)Si] ligand. [SiCSi]Ni(II) complex has been employed as catalyst for Ni-catalyzed Sonogashira reactions (8). Moreover bis(silylene) pincer complexes of iridium and rhodium reveal strong 5-donating ability of divalent silicon and have demonstrated selectivity in catalytic C—H borylation reactions with arenes (9). 

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