In the structures of the isostructural cocrystals [CuI3(CNXyl)3]·CHX3 (X = Br, I), two adjacent CuI-bound isocyanide groups, whose carbon lone pairs are blocked by the ligation, exhibit nucleophilic properties induced...

Cu I -catalyzed cycloaddition (CA) of the ketonitrones, Ph 2 C=N + (R′)O – (R′ = Me, CH 2 Ph), to the disubstituted cyanamides, NCNR 2 (R = Me 2 , Et 2 , (CH 2 ) 4 , (CH 2 ) 5 , (CH 2 ) 4 O, C 9 H 10 , (CH 2 Ph) 2 , Ph(Me)), gives the corresponding 5-amino-substituted 2,3-dihydro-1,2,4-oxadiazoles (15 examples) in good to moderate yields. The reaction proceeds under mild conditions (CH 2 Cl 2 , RT or 45 °C) and requires 10 mol % of [Cu(NCMe) 4 ](BF 4 ) as the catalyst. The somewhat reduced yields are due to the individual properties of 2,3-dihydro-1,2,4-oxadiazoles, which easily undergo ring opening via N—O bond splitting. Results of density functional theory calculations reveal that the CA of ketonitrones to Cu I -bound cyanamides is a concerted process, and the copper-catalyzed reaction is controlled by the predominant contribution of the HOMO dipole –LUMO dipolarophile interaction (group I by Sustmann’s classification). The metal-involving process is much more asynchronous and profitable from both kinetic and thermodynamic viewpoints than the hypothetical metal-free reaction.

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The crystal structure of [Cu2(μ-O)(μ-I)2(CNXyl)4]·I2 (2·I2) was determined from single-crystal X-ray diffraction data. The adduct 2·I2 represents the first example of structurally characterized isocyanide-copper(II) complexes. In the structure of 2·I2, 2 forms independent chains connected through molecular iodine via I···I–I···I halogen bonding. The DFT calculations and topological analysis of the electron density distribution within the formalism of Bader’s theory (QTAIM method) were performed for model complex 2·I2 and the obtained results allowed the attribution of these contacts to moderate strength (3.8–5.3 kcal/mol) non-covalent contacts exhibiting some covalent character.

Homoleptic copper(i) complexes featuring disubstituted cyanamides were obtained and characterized using experimental methods and their properties were studied theoretically.