Rhenium complexes water

Raman spectroscopy metal in water complexes, 309 Rare earth complexes acetylacetone synthesis, 377 guanidinium, 282 hydroxamic acids, 506 Redox properties bipyridyl metal complexes, 90 Reductive coupling nitrile metal complexes, 265 Resorcinol, 2,4-dinitro-metal complexes, 273 Rhenium complexes acetylacetone, 376 synthesis, 375, 378... 

The rhenium complexes described in Section 11.2 have also been studied as electron mediators for C02 reduction at metal electrodes. Hawecker et al. used the complex Re(bpy)(CO)3Cl in DMF/water (9 1) at glassy carbon electrodes at a potential of-1.44V (versus SCE) to produce CO with 98% faradaic efficiency [15, 87]. Likewise, Sullivan et al. reported the production of CO with similar efficiency at a platinum electrode at -1.5 V (versus SCE) by using the complex fac-Re(bpy) (CO)3Cl [88]. Ruthenium complexes that have been used in photochemical... 

These -propargyl rhenium complexes undergo kinetic addition of nucleophiles at the central C atom to produce rhenacyclobutenes. The nucleophiles range from PR3 to malonate, acetylides, pyridines, and water. The derivatives of the addition of pyridines, however, are unstable and undergo further rearrangements to allene or acetylene complexes. Protonation of the metaUacyclobutenes produces u -allyl complexes. 

Finally, insertion of alkynes into dihydrogen mononuclear cationic rhenium complexes, stabilized by the triphos (= l,l,l-tris(diphenylphosphinomethyl)ethane) ligand, leads to vinylidene derivatives which react with water or ethanol eliminating silanols or methane, Fig. 18. Solvents were acetone or THF no chromatography was used. 

Few dinitrogen complexes of chromium are known. Complex 8 decomposes at 20 C with loss of both N2 and PMes. Treatment of complex 9 with acid produces small quantities of ammonia (7%) and hydrazine (1%). Reaction of the polynuclear complex 10 with water regenerates the starting rhenium complex tran5-[ReCl(N2)(PMe2Ph)4], and with dioxygen produces the cation [ReCl(N2)(PMe2Ph)4]. ... 

With the aim of exploring RBA values of estradiol-rhenium complexes (for eventual exploitation as radiopharmaceuticals), molecule 18, in which the ethy-nylcyclopentadienyl-tricarbonylrhenium moiety - a standard 18-electron system - is attached at the lip-position, was prepared in a nine-step synthesis [143]. This product exhibits a value for the octanol/water partition coefficient, logPo/w, of 5.5, compared with 3.3 for estradiol itself this increased lipophiUcity is a general phenomenon for organometallics. The RBA of 18 was found to be 11%, whereas the corresponding value when the same-C=C-(C5H4)Re(CO)3... 

Homoleptic manganese(II) compounds are very unstable, pyrophoric, and very sensitive to water. Homoleptic rhenium complexes also readily react with oxygen, water, and alcohols. The compound Li2[Re2Meg] is also pyrophoric. Heteroleptic compounds, like compounds of elements of other groups, are less reactive. 

Under the influence of water, cationic manganese compounds decompose immediately, as in organic donor solvents such as acetone and tetrahydrofuran. In contrast to isoelectronic compounds of the chromium group, diolefin technetium and rhenium complexes have cis structures. In aqueous solution, the cation [Re(CO)4 ( 2114)2] is stable the Re —C2H4 bond in [Re(CO)5 ( 2114)] is also stable. There is no exchange between free ethylene and the ethylene in the complex. 

In order to apply LRC to the setting of hydraulic mortars we selected the water-soluble rhenium complex Na2[(Bacu)Re(CO)3Cl] with Bacu = bathocuproine disulfonate as LRC-active probe [3]. This yellow salt was yet unknown but could be syntliesized by a simple procedure. This compound is characterized by a luminescence which consist of a single emission band which undergoes a blue shift from Xmax == 598 imi in aqueous solution to... 

Anion dissociation during the second reduction step create the vacant site. The key step is the formation of a metallocarboxylic complex, formed by nucleophilic attack of the formal Re(-I) center on the electrophilic carbon of the CO2 substrate. Decomposition of this intermediate by protonation leads to the formation of carbon monoxide, water and the starting rhenium complex. 

Propylene oxide is also produced in Hquid-phase homogeneous oxidation reactions using various molybdenum-containing catalysts (209,210), cuprous oxide (211), rhenium compounds (212), or an organomonovalent gold(I) complex (213). Whereas gas-phase oxidation of propylene on silver catalysts results primarily in propylene oxide, water, and carbon dioxide as products, the Hquid-phase oxidation of propylene results in an array of oxidation products, such as propylene oxide, acrolein, propylene glycol, acetone, acetaldehyde, and others. 

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. 

In the case of the rhenium aqua-ion [Re(OH2)3(CO)3]+ (33b) the question has been posed whether complex-anion can be considered to be a Bronsted acid. Titrations with hydroxide in water yielded a pKa value of 7.55 which is exceptionally low for a +1 cation. After the deprotonation of one coordinated water molecule, polymer formation over (/r-OH) bridges was initiated and the two compounds [Re3(/T3-OH)(/T-OH)3(CO)9r (35) and [Re2(/i-OH)3(CO)6] were (36) isolated and structurally characterized (Scheme 6). 

Compared to 32 (see Sect. 3.2), these compounds have the advantage that they react quantitatively under ambient conditions, in water as well as in polar organic solvents. The behaviour towards the ligands depicted in Scheme 7 proved to be identical for rhenium and technetium. The compounds listed in Scheme 7 have been fully characterized. The heterogenous reaction in THF in the presence of isocyanides yielded quantitatively the neutral complex [TcC1(CN-R)2(CO)3]... 

The reactions of olefins with non-organometallic Tc(VII) compounds behaved similarly. In a recent study, [Tc03C1(AaA)] (86a) (in which AA stands for aromatic diamine derivatives) was shown to react quantitatively with olefins, and produce the corresponding Tc(V) diolato-complex [TcOC1(OaO)(AaA)] (87a). The process could not be run catalytically, as Tc(V) complexes tend to undergo disproportionation rather than reoxidation in the presence of water [97]. These alkene-glycol interconversions could not be performed with the analog Re(VII) compound. Rhenium displays completely contrary behaviour, in that alkenes can... 

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