Thorium derivative

The formation constants of an actinium isopropyltropolonate complex were determined. Thermochemically relevant studies of thorium enolates generally involve bis(pentamethyl-cyclopentadienyl)thorium derivatives. Cp 2Th(Cl)(C(0)CFl2Bu-f) with an anionic acyl group that readily rearranges to the isomeric enolate Cp 2Th(Cl)OCH=CHBu-t. The Z-isomer is formed upon heating and the -isomer upon catalysis with Cp 2ThH2. Is the E or Z enolate thermodynamically more stable For the simple alkyl enolates MeCH=CHOR, the equilibration reaction of the Z- and E-isomers is nearly thermo-neutral . Consider the two species Cp 2Th(H)OCH(Bu-t)2 and Cp 2Th(H)0-2,6-C6H3 (Bu-f)2. The reversible addition of CO yields the rp- formyl derivative in reactions that are 19 4 and 25 6 kJmoR exothermic. These formyl species dimerize to form the classical enediolate, Cp 2Th(OR)OCH=CHO(OR)ThCp 2. This product is formed as the Z-isomer, plausibly thermodynamically preferred over the -isomer, much as (Z)-MeOCH=CHOMe is preferred over its E-counterpart by 6.0 0.2 kJmoR. ... 

The monochlorotris-silylamides, [(Me3Si)3N]3MCI, of the two most readily accessible actinide elements, thorium and uranium, have been prepared by reaction of three molar equivalents of sodium bis(trimethylsilyl)amide and the metal chloride in tetrahydrofuran. The thorium derivative is a colorless, diamagnetic, pentane soluble compound which is rtionomeric in the gas phase (by mass spectrometry) (19, 20). The tan uranium analogue is paramagnetic (yB = 2.8 B.M.) (20). 

The diamagnetic, monomeric thorium derivative has been completely characterized by its 1h and 13C nuclear magnetic resonance spectra. Data are shown in Table II. In particular the NMR spectrum, proton-coupled, shows a triplet pattern clearly due to splitting by two equivalent hydrogen atoms. The uranium metallocycle is paramagnetic (yg = 2.7 B.M.) and we have only observed its NMR spectrum. A titanium metallocycle,... 

X-ray powder diffraction data reveal that CP3UCI and Cp3ThCl are isomor-phous. Tris(cyclopentadienyl)thorium derivatives of other halides, alkoxides, tetrahydroborates, etc., can be prepared in a manner analogous to the uranium reaction above [58]. Tris(cyclopentadienyl)neptunium chloride, Cp3NpCl, can be prepared either by a radiochemical synthesis [75] ... 

Copper versenate has been used as an ultraviolet indicator in the titrimetric determination of thorium Derivative plots... 

CyclooctatetraenylCompounds. Sandwich-type complexes of cyclooctatetraene (COT), CgH g, are well known. The chemistry of thorium—COT complexes is similar to that of its Cp analogues in steric number and electronic configurations. Thorocene [12702-09-9], COT2Th, (16), the simplest of the COT derivatives, has been prepared by the interaction of ThCl [10026-08-1] and two equivalents of K CgHg. Thorocene derivatives with alkyl-, sdyl-, and aryl-substituted COT ligands have also been described. These compounds are thermally stable, air-sensitive, and appear to have substantial ionic character. 

Thiol compounds 252, 254 Thione compounds 252, 254 Thiosemicarbazides, N-aryl- 248 Thiourea 107, 246,254, 269, 337 -, derivatives 322, 323 Thorium cations 144 Threonine 246 Thymol 153, 197, 198 -, derivatives 288 Tigogenin 59, 195 -, acetate 63 Tigogenone 59,60 Tillmans reagent 256 Tin, cations 144,311,398 -, organic derivatives see Organotin compounds... 

Buesseler KO, Ball L, Andrews J, Benitez-Nelson C, Belastock R, Chai F, Chao Y (1998) Upper ocean export of particulate organic carbon in the Arabian Sea derived from thorium-234. Deep-Sea Res II 45 2461-2487... 

Martin JM, Nijampurkar V, Salvation F (1978b) Uranium anti Thorium isotope behavior in estuarine systems. In Biogeochemistry of estuarine sediments. UNESCO, p 111-127 Mathieu D, Bemat M, Nahon D (1995) Short-lived U and Th isotope distribution in a tropical laterite derived from Granite (Pitinga river basin, Amazoitia, Brazil) application to assessment of weathering rate. Earth Planet Sci Lett 136 703-714... 

Vigier N, Bourdon B, Turner S, Allegre CJ (2001) Erosion timescales derived from U-decay series measurements in rivers. Earth Planet Sci Lett 193 549-563 von Gunten HR, Roessler E, Lowson RT, Reid PD, Short SA (1999) Distribution of uranium- and thorium series radionuclides in mineral phases of a weathered lateritic transect of a uranium ore body. Chem Geol 160 225-240... 

Once uranium is incorporated into buried bone, shell, coral, or speleothems, the isotope uranium-235 decays, initially into the short-lived isotope (thorium-231) and then into long-lived protoactinium-231. Uranium-238, on the other hand, decays first into two successive short-lived isotopes (thorium-234 and protoactinium-234) and only then into a long-lived isotope, uranium-234 (see Fig. 12). The decay of uranium-235 to long-lived protoactinium-231 is used to date events up to 150,000 years in age that of uranium-234 (derived from uranium-238) to thorium-230 is of use for dating events within the time range 1000-500,000 years. 

MOLTEN METAL EXPLOSIONS, PRECIOUS METAL DERIVATIVES PYROPHORIC METALS, REACTIVE METALS STEEL WOOL, THORIUM FURNACE RESIDUES... 

Thorium - the atomic number is 90 and the chemical symbol is Th. The name derives from Thor, the Scandanavian god of thunder . It was discovered in the mineral thorite (ThSi04) by the Swedish chemist Jons Jacob Berzelius in 1828. It was first isolated by the chemists D. Lely Jr. and L. Hamburger in 1914. 

---