The hexacarbonylmetalates( 1 -) of niobium and tantalum are oxidised by H + and halogens to give the [M,X,(CO),] - anions (X = CI, Br, or I). By exchange reactions, the p-acetato- and p-methoxocomplexes (X = 0,CMe or OMe) were also obtained. The crystal and molecular structure of [H (thf),] [ Nb,CI,(CO),] was investigated by X-ray diffraction methods. Crystals are triclinic, space group P i , with a = 16.283(3), b = 9.293(2), c = 9.050(2) A, 01 = 11 3.01 (2), p = 96.56(2), y = 98.39(2)", U = 1 224.7 A3, D, = 1.792 g CM-~ (Z = 2), p( Mo-K,) = 12.2 cm-'. The two niobium atoms of the dimeric anion are bridged by three chlorides located at the vertices of an approximately equilateral triangle perpendicular to the niobium-niobium vector [Nb Nb 3.631 (1 ) A]. The seven-co-ordination of niobium is completed by four carbonyl groups. The dimeric chloride- bridged complexes of niobium ( I) and tantalum( I) undergo the following reactions: (a) reduction by sodium to the hexacarbonylmetalate( 1 -); (6) chloride substitution by C,H,- to the cyclopentadienyl derivatives [M(q5-C5H5()C O),] in good yields and by arenes in the presence of aluminium bromide to the new cationic complexes [ M(qs-arene) (CO),] + as their hexa (bromo)chlorodialuminate derivatives.

NEW CARBONYL DERIVATIVES OF NIOBIUM(I) AND TANTALUM(I)

CALDERAZZO, FAUSTO;PAMPALONI, GUIDO;
1985

Abstract

The hexacarbonylmetalates( 1 -) of niobium and tantalum are oxidised by H + and halogens to give the [M,X,(CO),] - anions (X = CI, Br, or I). By exchange reactions, the p-acetato- and p-methoxocomplexes (X = 0,CMe or OMe) were also obtained. The crystal and molecular structure of [H (thf),] [ Nb,CI,(CO),] was investigated by X-ray diffraction methods. Crystals are triclinic, space group P i , with a = 16.283(3), b = 9.293(2), c = 9.050(2) A, 01 = 11 3.01 (2), p = 96.56(2), y = 98.39(2)", U = 1 224.7 A3, D, = 1.792 g CM-~ (Z = 2), p( Mo-K,) = 12.2 cm-'. The two niobium atoms of the dimeric anion are bridged by three chlorides located at the vertices of an approximately equilateral triangle perpendicular to the niobium-niobium vector [Nb Nb 3.631 (1 ) A]. The seven-co-ordination of niobium is completed by four carbonyl groups. The dimeric chloride- bridged complexes of niobium ( I) and tantalum( I) undergo the following reactions: (a) reduction by sodium to the hexacarbonylmetalate( 1 -); (6) chloride substitution by C,H,- to the cyclopentadienyl derivatives [M(q5-C5H5()C O),] in good yields and by arenes in the presence of aluminium bromide to the new cationic complexes [ M(qs-arene) (CO),] + as their hexa (bromo)chlorodialuminate derivatives.
Calderazzo, Fausto; Castellani, M; Pampaloni, Guido; Zanazzi, Pf
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11568/3787
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