Phosphorus heterocycles transition metal complexes

Phosphorus-containing macrocycles, 990, 996, 998 macrocychc effect, 1002 ring size, 1003 stereochemistry, 1003 Phosphorus heterocycles transition metal complexes, 1041 Phosphorus ligands, 989-1061 ir-acid series, 1033 bonding, 1030-1041 cone angle concept, 1012 trigonal bipyramidal complexes, 1036 Phosphorus oxychloride metal complexes, 500 Phosphorus ylides transition metal complexes, 1056 Phosphorylation biological, 978 Phosvitin, 975 Photochromism... 

As well as phosphorus ligands, heterocyclic carbenes ligands 10 have proven to be interesting donor ligands for stabilization of transition metal complexes (especially palladium) in ionic liquids. The imidazolium cation is usually presumed to be a simple inert component of the solvent system. However, the proton on the carbon atom at position 2 in the imidazolium is acidic and this carbon atom can be depro-tonated by, for example, basic ligands of the metal complex, to form carbenes (Scheme 5.3-2). 

The 1,2,4,3-triazaphospholes are colorless or pale yellow distillable liquids or crystalline solids. They are not oxidized by air and are reluctant to react with sulfur. Three isomeric heterocyclic systems of 277-1,2,4,3-triazaphospholes 15, 177-1,2,4,3-triazaphospholes 16, and 477-1,2,4,3-triazaphospholes 17 are known and they differ considerably in their behavior <1996CHEC-II(4)771>. The synthesis of 1,2,4,3-triazaphospholes and reactivity of different isomers of 1,2,4,3-triazaphospholes in the reactions at a ring nitrogen, in the addition to the P=N bond, oxidative addition to the ring phosphorus, cycloaddition reactions, and the formation of transition metal complexes are systematically covered in CHEC-II(1996) <1996CHEC-II(4)771>. The 1,3,4,2-thiadiazaphospholium ions 18 are only briefly mentioned in CHEC-II(1996) and no new results on their chemistry have been published in the last decade. 

The photochemistry of transition carbonyl complexes of chromium or iron with phosphirane or l//-phosphirene ligands is studied with time-dependent DFT theory to explore the propensity of the excited metal-phosphine-carbonyl complexes to expel their ligands <2003JA3558>. The complexes of these phosphorus heterocycles show similar behavior as carbonyl complexes with the PH3 ligand and they differ mainly in their enhanced a-donating ability. The calculations point that the excited complexes prefer the expulsion of the phosphorus substituents, which can be an alternative method to demetalate transition metal complexes of organophosphorus compounds. 

A125. F. G. Mann, Chemistry of Heterocyclic Compounds, Vol. 1 Heterocyclic Derivatives of Phosphorus, Arsenic, Antimony and Bismuth, 2nd ed. Wiley (Interscience), New York, 1970. A much shorter first edition was published in 1950. A126. C. A. McAuliffe, ed., Transition Metal Complexes of Phosphorus, Arsenic and Antimony ligands. Macmillan, New York, 1973. 

As well as phosphorus ligands, heterocyclic carbene ligands 10 have proven to be interesting donor ligands for stabilization of transition metal complexes (especially palladium) in ionic liquids. The imidazolium cation is usually presumed to... 

From phosphorus heterocycles to phosphorus analogues of unsaturated hydrocarbon-transition metal 7r-complexes. J. Organomet. Chem. 400, 149 (1990). 

The complex of tartaric acid and antimony (emetic) was described three centuries ago. Nevertheless, the structure of this compound has been elucidated these last fifteen years by X-ray diffraction ( 1 ). In fact, emetic presents a binuclear cyclic structure. Many authors mentioned similar complex with transition metals (vanadium (2), chromium (3)) or metalloids (arsenic (4), bismuth (5)). Emetic with phosphorus was not mentioned. Nevertheless, tartaric acid or alkyl tartrates has been utilized in phosphorus chemistry tartaric acid reacts with trialkyl phosphites giving heterocyclic phosphites (6). Starting from alkyl tartrates, we prepared spirophosphoranes with a P-H bond and sixco-ordinated compounds (7). With unprotected tartaric acid, many possibilities appear condensation as a diol, as a di(oc-hydro-xyacid), or even as a 8-hydroxyacid. 

Palladium complexes with an heterocyclic N-containing ligand have been used in the carbonylation of aromatic nitro compounds with cocatalysts such as cyclopentadienyl halides or oxyhalides of transition metals belonging to group V e.g. CP2VCI) [168], a cyclopentadienyl halide or oxyhalide together with phosphorus oxytrichloride [169], or a 1,3-diketone derivative of vanadium [170], even also in the presenee of phosphorus oxychloride [171]. 

A number of reviews with relevant material address K-complexes of various kinds and iiKlude reviews on the syntheses of cationic 7t-complexes of the transition metals, die activation of C-C bonds in unsaturated hydrocarbons by metal complexes, a review on phosphorus heterocycles and phosphorus analogues of unsaturated hydrocarbon transition metal n-omiplexes J metal-complex catalyzed polymerizations of a-alkenes, coordination equilibria and coupling leactitms of unsaturated hydrocarbons at a metal centre, oligomerization of a-alkenes to higher oligomers, an annual survey on the chemistry of selected n-complexes for the year 1989, an annual survey on the chemistry of ferrocene for the year 1989, and in a number of articles in a journal issue devoted to alkene metathesis. 

Unusual type of P-based cyclophane 154 containing NH,NH-functionalized carbene heterocyclic fragment coordinated to the transition metal was obtained by metal template assisted cyclization reactions of the diphosphine hgand bearing reactive 2-fluoro substiments at phenyl groups on phosphorus atoms and carbene heterocycle in coordination sphere of 153 (Scheme 12.57). Aerial oxidation of the complexes of the cyclophane hgand resulted in the isolation of the free macrocycle as di(phosphine oxide)/imidazolidinium salt [142, 143]. 

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