Copper-amine-carbonyl chemistry. Solution and solid-state studies of the copper(I)-ethylenediamine-carbon monoxide system: Synthesis and X-ray structures of mononuclear and binuclear copper(I)-carbonyl complexes

Article abstract of DOI:10.1021/ic50207a016

Copper(I) iodide in methanol absorbs carbon monoxide at room temperature and atmospheric pressure in the presence of ethylenediamine, en, giving colorless solution. Depending on the Cu^I/en molar ratio and the anion present, the following thermally stable copper(I) carbonyls have been isolated as white crystals: [Cu(en)₂(CO)]I (I) [v_CO(Nujol) 2060 cm^-1]; [Cu₂(en)₃(CO)₂]I₂ (II) [v_CO(Nujol) 2062 cm^-1]; [Cu₂(en)₃(CO)₂](PPh₄)₂ (III) [v_CO(Nujol) 2078 cm^-1]. The structure of III consists of discrete dimeric cations [Cu₂(en)₃(CO)₂]²⁺ and BPh₄^- anions. The two centrosymmetric copper atoms are surrounded ,n a pseudotetrahedral geometry by a set of three nitrogen atoms, provided by one chelating and one bridging en, and a carbon monoxide molecule. The bond distances associated with the Cu-C-O units are Cu-C = 1.73 (1) and 1.75 (1) ? and C-O = 1.17 (2) 1.16 (2) ?. The addition of NaBPh₄ to a methanolic solution of Cu(en)COCl (IV) gives at -20°C white crystals of [Cu(en)(CO)PhBPh₃] (V) [v_CO(Nujol) 2117 cm^-1]. The ion-pair nature of V was established by an X-ray analysis. Copper(I) interacts with both a carbon monoxide molecule and one of the C=C bonds of the BPh₄^- anion, in a pseudo-trigonal-pyramidal geometry completed by an ethylenediamine molecule. The Cu-C and C-O bond distances are 1.806 (6) and 1.110 (7) ?, respectively. Crystallographic details for III are as follows: space group P2₁/n (monoclinic), a = 13.769 (2) ?, b = 19.184 (3) ?, c = 9.833 (2) ?, β = 90.99 (2)° V = 2596.9 ?³ Z = 2. The final R factor was 4.7% for 3088 observed reflections. Crystallographic details for V are as follows: space group P2₁/c (monoclinic), a = 10.301 (1) ?, b = 12.234 (1) ?, c = 18.390 (2) ?, β = 91.11 (1)°, V = 2317.1 ?³, Z = 4. The final R factor was 4.9% for 3150 observed reflections.