Oxygen rhenium

Compilation of Rhenium-Oxygen and Other Bond Distances in Oxo-, and Imido- and Thio-rhenium Compounds... 

It seems not entirely coincidental that the most effective catalysts are those with a pre-existing rhenium-oxygen bond indeed, in our studies none that lack this feature are active. According to MO analysis, the... 

An excellent correlation is obtained with rhenium-oxygen bond... 

Infrared data were consistent with the presence of coordinated tertiary phosphines and the absence of rhenium-oxygen contaminants. The low-frequency bands assigned to Re—G stretching modes displayed the normal shift to lower frequency upon reduction of the metal in the series Re2G6(PR3)2 > Re2 Cls (PR3 )3 > Re2 Cl4(PR3)4 (124). 

Potassium nitridorhenate(VII) is a pale yellow solid, insoluble in liquid ammonia but soluble in water with decomposition. When dry, it does not decompose rapidly in air but becomes white when heated. The infrared spectrum3 of the solid has a strong peak at 1025 cm.-1, attributable to rhenium-nitrogen stretching, and sharp peaks at 909 and 936 cm.-1, attributable to rhenium-oxygen (cf. 912 cm.-1 in Re04"). 

The most prevalent complexes of this oxidation state are those which contain the [ReO] ", [Re02] and [RejOj] moieties, a reflection of the increasing stability of the rhenium-oxygen bond as the oxidation state increases. The tendency of Re to form multiple bonds (as in [Re=0] and [0=Re=0] ) is also seen in its behavior toward nitrogen, viz. the stabilization of the [Re=N] (nitrido) and [Re=NR] + (nitrene) moieties. With few exceptions, complexes of Re have been found to be essentially diamagnetic, i.e. to contain a spin-paired configuration. Because of the dominance of the [ReO] +, [Re02] and [RejOj] units in the chemistry of Re, such complexes will be considered first in the chemistry of this oxidation state. 

The molecular geometry of is depicted in Figs. 1, giving proof that we are indeed dealing with a mononuclear species containing short rhenium-oxygen bonds. The ReO interatomic distances of ca. 171 pm are... 

The terminal rhenitim-oxygen bond lengths are in the range 168-172 pm in all compo mds considered here. For comparison, the rhenium-oxygen bond lengths of some inorganic oxorhenium compotmds are summarized below ... 

Oxidative Garbonylation. Carbon monoxide is rapidly oxidized to carbon dioxide however, under proper conditions, carbon monoxide and oxygen react with organic molecules to form carboxyUc acids or esters. With olefins, unsaturated carboxyUc acids are produced, whereas alcohols yield esters of carbonic or oxalic acid. The formation of acryUc and methacrylic acid is carried out in the Hquid phase at 10 MPa (100 atm) and 110°C using palladium chloride or rhenium chloride catalysts (eq. 19) (64,65). 

Silver coatings may blister above 200°C because of oxygen diffusion. A nickel undercoat stops interdiffusion with a copper substrate above 150°C. Alloying with antimony, selenium, sulphur or rhenium increases hardness—the coefficient of friction is also much reduced in the last case. ... 

The rhenium interacts strongly with the oxygen atoms of the support and also with platinum platinum interacts less strongly with the support than rhenium. One is tempted to generalize that when one of the metals in a supported bimetallic cluster is noble and the other oxophihc, the oxophUic metal interacts more strongly with the support than the noble metal if the bimetalhc frame of the precursor is maintained nearly intact, then this metal-support interaction helps keep the noble metal highly dispersed. 

Another type of ligand is the monoanionic, tridentate oxygen donor [(C5H4R)Co-(P(0)R R")3] (Lor), which has been used to prepare the complexes of technetium [37] and rhenium [38] [M03L] and [MOX2L] (X Cl, Br). These complexes are stable in organic solvents but hydrolyse slowly in water. In order to evaluate their usefulness in radioimmunotherapy, the corresponding compounds were also prepared with radioactive rhenium isotopes. 

Because several of the superalloys contain very little iron, they are closely related to some of the non-ferrous alloys. Some of the second- and third-row transition metals possess many of the desirable properties of superalloys. They maintain their strength at high temperatures, but they may be somewhat reactive with oxygen under these conditions. These metals are known as refractory metals, and they include niobium, molybdenum, tantalum, tungsten, and rhenium. 

Oxygen Transfer Reactions Catalysis by Rhenium Compounds James H. Espenson... 

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