Oxygen complexes reacting with

Nickel(IV) complexes react with dimethyl sulphoxide in acidic solution to give the sulphone and nickel(II) ions. The kinetics of this reaction have been studied and found to be very complex in nature. The reaction probably proceeds by initial complexation of the dimethyl sulphoxide to the nickel(IV) species followed by electron transfer and oxygen atom transfer producing the observed products149. 

The [Co(DH)2L] complexes react with oxygen 137) to give j -peroxo complexes LCo(DH)2-02-Co(DH)2L, isolated using several ligands (not isocyanides however). These adducts are labile, and oxygen is easily lost. On standing these complexes can undergo oxidation, however, to /x-superoxo... 

The potential synthetic utility of titanium-based olefin metathesis and related reactions is evident from the extensive documentation outlined above. Titanium carbene complexes react with organic molecules possessing a carbon—carbon or carbon—oxygen double bond to produce, as metathesis products, a variety of acyclic and cyclic unsaturated compounds. Furthermore, the four-membered titanacydes formed by the reactions of the carbene complexes with alkynes or nitriles serve as useful reagents for the preparation of functionalized compounds. Since various types of titanium carbene complexes and their equivalents are now readily available, these reactions constitute convenient tools available to synthetic chemists. 

Thermodynamic Properties of Cobalt Complexes Reacting with Oxygen... 

These Co(II) complexes react with molecular oxygen by a two stage mechanism a first step with rapid formation of a 1 1 metal-dioxygen complex, followed by the slower formation of a 2 1 complex (believed to be responsible for the irreversible coordination of oxygen) according to the sequence ... 

A wide range of carbon, nitrogen, and oxygen nucleophiles react with allylic esters in the presence of iridium catalysts to form branched allylic substitution products. The bulk of the recent literature on iridium-catalyzed allylic substitution has focused on catalysts derived from [Ir(COD)Cl]2 and phosphoramidite ligands. These complexes catalyze the formation of enantiomerically enriched allylic amines, allylic ethers, and (3-branched y-8 unsaturated carbonyl compounds. The latest generation and most commonly used of these catalysts (Scheme 1) consists of a cyclometalated iridium-phosphoramidite core chelated by 1,5-cyclooctadiene. A fifth coordination site is occupied in catalyst precursors by an additional -phosphoramidite or ethylene. The phosphoramidite that is used to generate the metalacyclic core typically contains one BlNOLate and one bis-arylethylamino group on phosphorus. 

The greater effectiveness of hydrogen peroxide is also shown in the reactions of the pentacoordinated complexes [M(A -L )(cod)] supported by N-donor hgands (L = dpa-R [72,79], Cn [79], PysSs [81]) (Fig. 5). While these complexes are unreactive with molecular oxygen, they react with H2O2 to systematically give the l-hydroxy-2-metalla (5,6,7)-allyl derivatives (Scheme 12) as the thermodynamic products. 

But most of the Co(II) complexes react with molecular oxygen to yield binuclear dioxo-bridged species of the type (B)(S)Co-02-Co(SXB), and these may be readily oxidized to the corresponding super dioxo-bridged complexes, Co(III)—02 —Co(III). 

A polymer ligand might be expected to protect the dioxygen-metal complex against autoxidation in much the same way as the globin protein does. In this chapter, we describe how polymer-metal complexes react with molecular oxygen and introduce attempts to construct synthetic oxygen carriers. 

H202(H20)(RS-) become important Oxygen also reacts with Fe(lll)(OH)(RS)2-2 to produce ferrous iron, and thus, appears to react with the ferric complex in a manner analogous to that of the radicals ... 

NbCl2(RCp)2] (R = H, Me) complexes react with H202, affording [Nb(02)Cl(RCp)2]. In the complex with R = H the two oxygen atoms (O—O 1.47(1) A) and the chlorine atom are in the plane which bisects the Nb(Cp)2 bent sandwich system the coordination around niobium is thus pseudotetrahedral. In the presence of H202, [Nb(02)Cl(Cp)2] catalytically converts cyclohexene to its epoxide. 

Presumably the complex forms by electrophilic attack of the C02 carbon on the electron-rich metal center, followed by a similar electrophilic attack of the second C02 on the more basic oxygen of the coordinated C02, forming an oxygen-carbon bond. The metallocycle ring closing then completes the complex formation. Support for this mechanism comes from infrared spectra implicating a mono-C02 adduct that is observed when the starting metal complex reacts with less than two equivalents of C02. 

Electrochemical or Li-benzophenone reduction of Fe(Pc) and Co(Pc) gives [M Pc] and [M (Pc)]2. 198,199 These monovalent metal complexes react with alkyl halides to give organometallic compounds which transfer the alkyl group to alkenes in the presence of Pd11 salts (Scheme 61). [Co PCTS]5- and [Co PCTS]6- reductively bind one and two molecules of oxygen respectively in DMF,198 The second 02 addition is reversible (Scheme 62). 

Two different metal-C02 complex intermediates have been proposed for the production of CO-metallocarboxylates and metal formates. The difference between the two species is based on the site of protonation, at the carbon atom in metallocarboxylates and at one of the oxygen atoms in metal formates. Carbon-protonation has not been observed experimentally, while oxygen-protonation is well known [9]. Isomerization can occur between metallocarboxylates and metal formates, and loss of a hydroxide group from the metal formate species yields the M-CO complex. Similarly, the direct reaction of metal complexes with free, dissolved C02 has also been described. In this mechanism, the metal complex reacts with an oxide acceptor, such as C02, generating the metal-CO complex and C032- [9],... 

The complexes react with oxygen to form metal oxides (eq. 18). This reaction is likely a radical trapping reaction but may involve excited state electron transfer. 

Oxygen molecules react with Au - OH clusters only when n is even.12 It is worth noting that an AU-O2 complex has been detected in matrix isolation chemistry. When gold atoms and oxygen were co-condensed with a rare gas at extremely low temperature, a green complex was formed in which the oxygen was bonded sideways on. 

To account for the reactivity of 19 toward oxygen atom donors, a catalytic cycle was proposed. In this mechanism, the diferrous complex reacts with an oxygen donor to give an adduct with 19 that can either act as the atom transfer species or collapse to a ferry 1 species [Fe4+ = 0] intermediate. The data currently available does not allow for a more detailed description, although spectroscopic characterization and determination of the kinetic competence of the observed intermediate will allow the differentiation of several possible pathways. 

The proton magnetic resonance spectrum has a doublet centered at t 27.1 (stretching frequency, in the infrared spectrum (Nujol mull), is at 2079(s) cm.-1. The interaction of the complex with alkenes produces5 stable alkyl complexes of the type [Rh(NH3)5R]S04. In solution the complex reacts with molecular oxygen to give a blue peroxo complex displacement of ammonia by ethylenediamine can also be achieved.6... 

The thermal decomposition of [RhCl(PPh3)3] has been investigated twice. The first investigation revealed that the complex reacted with oxygen between 100 and 165°C, but decomposed in a helium atmosphere at 210°C.180 The second proposed that biaryls were formed when [RhCl(PPh3)3] and its congeners were heated above 140°C.181... 

Methyltrioxorhenium (MTO) is an extensively used catalyst for olefin epoxidation1241 and a number of reviews are available on its application.125"281 The complex reacts with hydrogen peroxide to form the mono r 2-peroxo species mpMTO and the diperoxide dpMTO. Both complexes are capable of transferring an oxygen atom to olefins or other substrates, as shown in Scheme 5.1, but the diperoxide species is about five times more reactive than the monoperoxo complex.1171 Care has to be taken that halide impurities are absent from the solvent as these are oxidised much faster than olefins.1171... 

The structure of mer-Mo(CO)3(S02)(PPr 3)2 was found to contain j -planar rather than if SO2 geometry. The phosphines are mutually trans, and the rotational orientation is such that the S-O and M-CO bonds eclipse one another. Although the M-S bond is the longest reported for / -planar SO2, the SO2 is not labile. The complex reacts with molecular oxygen in solution with decomposition rather than sulfato formation. 

Cr porphyrin complexes react with O2 to form stable oxochromium(IV) species. Por example, the red [(TPP)CrO] contains a five-coordinate Cr displaced out of the porphyrin plane toward the oxygen atom (Cr-O, 157.2pm). There are also a few Cr scorpionates featuring terminally bound 0x0 ligands. The most recent of these is paramagnetic [Tp Cr(pz H)(0)]BARP (Cr-O, 160.2pm), which abstracts weakly bound hydrogen atoms from hydrocarbons. ... 

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