94249-98-6Relevant academic research and scientific papers
Reaction of copper(I)-N,N′-ethylenebis(benzaldimine) complexes with carbon monoxide and isocyanides
Toth, Andras,Floriani, Carlo,Pasquali, Marco,Chiesi-Villa, Angiola,Gaetani-Manfredotti, Amelia,Guastini, Carlo
, p. 648 - 653 (2008/10/08)
Copper(I) halides, CuX (X = Cl, I), react with N,N′-ethylenebis(benzaldimine), BEN (PhCH=NCH2CH2N=CHPh), in a 1:1 molar ratio to form final products that are probably the dimers [Cu2X2(BEN)2] (II) via the intermediacy of monomeric solvated species, [Cu(X)(BEN)(S)] (I). A monomeric complex is isolated, when S = CO, by reacting CuI with BEN in a carbon monoxide atmosphere ([Cu(BEN)(CO)(I)] (III), v(C-O) = 2066 cm-1). With p-tolyl isocyanide the analogous monomeric complex [Cu(BEN)(p-MeC6H4NC)(I)] (IV) (v(C-N) = 2135 cm-1) is formed. The structures of complexes III and IV were determined by X-ray analyses, showing pseudotetrahedral coordination geometry for Cu(I) in both complexes (C-O = 1.12 (2) A?, p-MeC6H4N-C = 1.17 (1) A?). Derivative III represents the first example of a monomeric complex containing the [X-Cu-CO] fragment. When CuI is reacted with an excess of BEN under a carbon monoxide atmosphere and in the presence of NaBPh4, ionization occurs to form [Cu(BEN)2](BPh4) (V). The cation [Cu(BEN)2]+ possesses S4 symmetry. In complexes II-V the C-N bond distances and stretching vibrations of ligated BEN are only slightly affected by the coordination to copper(I) and vary as follows: 1.267 (5)-1.28 (1) ?; 1625-1635 cm-1. The ligated BEN does not cause a significant disproportionation of copper(I) to copper(II) and copper metal, even in the absence of carbon monoxide, while providing the appropriate electronic properties for binding CO. Such a ligand as BEN seems to affect the electronic balance at the metal by an extent that is intermediate between those of saturated amino ligands and of nitrogen donor heterocycles such as pyridine and 2,2′-bipyridine. Carbonylation of [Cu(PhCO2)]4, carried out in the presence of BEN, allows the isolation in the solid state of a dicopper(I) complex containing a bridging carbonyl (v(C-O) = 1958 cm-1 (Nujol)), [Cu2(PhCO2)2(BEN)(μ-CO)] (X). Crystallographic details for complexes III-V are as follows: complex III, space group P21/n (monoclinic), a = 7.113 (2) ?, b = 17.204 (4) ?, c = 14.794 (4) ?, β = 97.87 (3)°, Z = 4, Dcalcd = 1.68 g cm-3, V = 1793.3 (8) ?3, final R factor 0.043 for 1698 observed reflections; complex IV, space group P1 (triclinic), a = 10.139 (7) ?, b = 13.427 (6) ?, c = 9.830 (4) ?, ? = 91.56 (5)°, β = 111.31 (5)°, γ = 108.54 (5)°, Z = 2, Dcalcd = 1.55 g cm-3, V = 1167 (1) ?3, R factor 0.042 for 2464 observed reflections; complex V, space group I41/a (tetragonal), a = 17.167 (2) ?, b = 17.167 (2) ?, c = 15.463 (1) ?, Z = 4, Dcalcd = 1.24 g cm-3, V = 4557.0 (9) ?3, final R factor 0.040 for 1049 observed reflections.
