Molybdenum, determination tris

Various approaches to the analysis of dissolved silicon have been tried. Most of them are based on the formation of /J-molybdosilic acid [ 199-203 ]. Dissolved silicon exists in seawater almost entirely as undissociated orthosilicic acid. This form and its dimer, termed reactive silicate , combine with molybdosilicic acid to form a- and /I-molybdosilicic acid [180]. The molybdosilicic acid can be reduced to molybdenum blue, which is determined photometrically [206]. The photometric determination of silicate as molybdenum blue is sufficiently sensitive for most seawater samples. It is amenable to automated analysis by segmented continuous flow analysers [206-208]. Most recent analyses of silicate in seawater have, therefore, used this chemistry. Furthermore, reactive silicate is probably the only silicon species in seawater that can be used by siliceous organisms [204]. 

Tri-n-octylphosphine oxide (TOPO) has been the most popular phosphine oxide to be used as an extractant for the determination of iron, uranium, plutonium, molybdenum, titanium and thorium among other metals.43 44... 

A series of polyether macrocycles (40)-(47) that contain a coordinated reducible transition metal redox-active 16-electron molybdenum nitro-syl Mo(NO) 3+ group have been prepared by us in collaboration with McCleverty and Jones (86,87) (Scheme 14). Compounds (40)-(44) were synthesized from the reactions between [Mo(NO)LX2] (L = tris(3,5-dimethylpyrazolyl)hydroborate X = Cl or I) and the appropriate amine-substituted benzo crown ether. Compounds (45)—(47) were prepared from reactions between [Mo(NO)LI2] and tetra-, penta-, or hexa-ethylene glycol, respectively, in the presence of triethylamine. A crystal structure determination of (45) (88) is shown in Fig. 14. 

Tris(2,4-pentanedionato)molybdenum(III) is a dark purple crystalline solid, m.p. 228 to 230°. It reacts rapidly with atmospheric oxygen to form a diamagnetic brown product, m.p. 284 to 285° (decomp.), containing pentaposi-tive molybdenum. This oxidation state is determined by dissolution in concentrated hydrochloric acid to produce a solution which has the same absorption spectrum in the visible region as green oxopentachloromolybdate(V), by cerimetric titration of this concentrated hydrochloric acid solution after chloroform extraction of the liberated 2,4-pen-tanedione, and by independent synthesis from a brown... 

A number of transition metals can be determined conveniently if their cations undergo a definite change of oxidation state see Oxidation Number) on titration with a standard solution of potassium permanganate, potassium dichromate, cerium(IV) sulfate, or ammonium hexanitratocerate(IV). Several visual indicators have been proposed, including diphenylamine and its derivatives, xylene cyanole FF, and especially A-phenylanthranilic acid and tris(l,10-phenanthroline)iron(II) sulfate ( ferroin ). Solutions of have been used in the determination of iron, copper, titanium, vanadium, molybdenum, tungsten, mercury, gold, silver, and bismuth, and standard solutions of and Sn F U, and and Mo have also... 

The X-ray crystal structure of the tris( n4-naphthalene)zirconate(2-) anion as the bis[K(2,2,2-crypt)] salt has been determined, revealing a trigonal prismatic coordination geometry of local Csv symmetry about the zirconium atom, as defined by the mid-points of the C-C vectors of the coordinated diene units, similar to that eviously observed for the isoelectronic tris(ii i-butadiene)molybdenum complex. 

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