Crystal structures and nitrosation reactions of triazido complexes of chromium(III)

Abstract

Two triazido chromium(III) complexes [Cr(tame)(N 3 ) 3 ] Á H 2 O (1) and [Cr(tacn)(N 3 ) 3 ] (2) (tame ¼ 1,1,1-tris(aminomethyl)ethane and tacn ¼ 1,4,7-triazacyclononane) have been prepared and characterized by single-crystal X-ray crystallography at 122 K. The crystal structure of 1 is monoclinic, space group P2 1 /c, with a ¼ 9.2460(9), b ¼ 11.0500(11), c ¼ 13.1980(9) Å , ¼ 97.244(7) with four formula units in the cell. The crystal structure of 2 is triclinic, space group P " 1, with a ¼ 7.698(4), b ¼ 8.5800 (6), c ¼ 10.236(3) Å , a ¼ 89.497(15), ¼ 83.70(2), ¼ 72.83(2) with two formula units in the cell. The reactions between NOBF 4 and 1 or 2 in acetonitrile give [Cr(tame)(NCCH 3 ) 3 ](BF 4 ) 3 and [Cr(tacn)(NCCH 3 ) 3 ](BF 4 ) 3 , respectively.

Crystal Structure and Spectroscopic Properties of cis‐β‐Diazido(1,4,7,11‐tetraazaundecane)chromium(III) Bromide

“…, respectively. [32,33] The arrangement of the azido ligands is essentially linear, the N-N-N angles being 176.6(6)-176.9(6)°. The inner N-N bond lengths of 1.209(7) and 1.206 (7) Å are slightly longer than the terminal N-N bond lengths of 1.142(8) and 1.148 (7) Å, in agreement with those commonly observed for monodentate non-bridging azido ligands.…”

“…The assignment of geometrical configuration can be confirmed by inspection of the d-d absorption spectra. [7,[15][16][17][18][19][26][27][28][29][30][31][32][33] The positions of the spin-allowed transitions in the electronic spectra, the number of bands, and their coefficients are usually reliable indicators for distinguishing between cis and trans geometrical isomers. It is well known that the more symmetrical trans chromium(III) complexes have three or four bands in the visible region, and these bands are located at higher wavelengths and have lower extinction coefficients than those of the less symmetrical cis isomers.…”