Lewis-Base Adducts of Group 11 Metal(I) Compounds. LXVI Synthesis, Spectroscopy and Structural Systematics of Some 1 : 3 Adducts of Copper(I) Compounds with Triphenylstibine, [(Ph3Sb)3CuX], X = Br, I, ONO2

Abstract

The syntheses of adducts, [(Ph₃Sb)₃CuX], X = Br, I, NO₃, obtained by crystallization of 1 : 3 CuX/SbPh₃ mixtures from appropriate solvents are described, together with their room-temperature single-crystal X-ray structure determinations. The bromide, obtained as a chloroform monosolvate from that solvent, is triclinic, P^-1, a 13·861(4), b 14·306(4), c 14·347(4) Å, α 84·40(2), β 86·93(2), γ 75·56(2)°, Z = 2 f.u., conventional R on F being 0·053 for N_o = 4136 independent ‘observed’ (I > 3σ(I)) reflections; this solvate is isomorphous with its previously recorded chloride counterpart. The iodide is triclinic, P^-1, a 14·55(1), b 14·385(2), c 23·626(6) Å, α 91·78(1), β 90·77(4), γ 92·54(5)°; Z= 4, R 0·050 for N_o 6917, and isomorphous with its phosphorus counterpart. The nitrate, although a methanol sesquisolvate, is also isomorphous with the chloride and bromide, a 13·369(9), b 14·398(3), c 14· 504(12) Å, α 82·29(5), β 84·39(6), γ 75·11(4)°, R 0·052 for N_o 5672. Cu-X are (2·235(5) (Cl)), 2·366(3) (Br), 2· 556(2) ( 2 ) (I), 1·98(1) Å (ONO₂), appreciably shorter than in their previously recorded EPh₃, E = P, As counterparts. The far-infrared spectra of [(Ph₃Sb)₃CuX] showed no clear v(CuX) bands, in contrast to the situation reported previously for the corresponding Ph₃P and Ph₃As compounds. It is likely that v(CuCl) is masked by a strong band at 270 cm^-1 due to the Ph₃Sb ligand. However, the region below 250 cm^-1 in which the v(CuX) bands are expected for the X = Br, I complexes contains no strong ligand bands. Possible reasons for the absence of v(CuX) bands in these complexes are considered.