The Preparation of Tantalum(IV) Bromide, Tantalum(IV) Iodide, and Pyridine Adducts of the Tantalum(IV) Halides

Organometallic Niobium and Tantalum Complexes with Primary Phosphine Ligands: Syntheses and Molecular Structures of [Cp*MCl4(PH2R)] (M = Nb, Ta; Cp* = C5Me5;R = But, Ad, Cy, Ph, 2, 4, 6-Me3C6H2 (Mes))

“…Similarly, [MCl 5 ] 2 (M ϭ Nb, Ta) were reported to be reduced to M(IV) by aliphatic [18] and aromatic [19] amines. [20].…”

Synthesis and characterization of metal--metal bonded dimers of tantalum and tungsten

“…An x-ray study of niobium tetrachloride (5) confirmed the pairwise interaction in that case; the shorter niobium-niobium separation along the one-dimensional chain of edge-shared O octahedra was found to be 3.06A. The remaining chloride and bromide 4+ analogues appear to be isomorphous with NbCl^ based on powder pattern x-ray data (13).…”

“…Tantalum pentachloride is much more difficult to reduce than is its niobium counterpart. Schafer and Kahlenberg have described the synthesis of TaCl^ (12) while McCarley and Boat man have described a convenient preparation of TaBr^ involving aluminum foil as the reducing agent (13). The metal pentabromide can be formed from elemental tantalum and bromine followed by a temperature gradient reaction to form tantalum tetrabromide.…”

“…Once more the corresponding tan talum system requires more stringent conditions if reduction is to occur. Vapor phase reduction of Talg with aluminum metal in a gradient of 500°C (aluminum) to 350®C (tantalum pentaiodide) produces Tal^ over a period of seven days (13). A preferable route to tantalum tetraiodide utilizes Tal^(py)2, (py = pyri dine) , which quantitatively loses pyridine when evacuated at 200®C for two days (13).…”

“…<],(ll) • 2^12) 6 (13) e"*(i5) e (16) \- Another molybdenum dimer of importance which has been characterized by x-ray diffraction is Rb2Mo2Clg (103). Al-7 -though the Mo2Clg " dimer is formed from Mo2(02CCH2)^ treated with hydrochloric acid at 60°C followed by addition of rubidi um chloride, the product is not structurally similar to the parent compound but rather adopts a structure based on the confacial bioctahedral conformation of Cs2Mo2Clg.…”