Tris(3,5-dimethylpyrazolyl)methane copper(I) complexes featuring one disubstituted cyanamide ligand

• Published in: Inorganica Chimica Acta Vol. 484; pp. 69 - 74
• Main Authors: Melekhova, Anna A., Novikov, Alexander S., Dubovtsev, Alexey Yu, Zolotarev, Andrey A., Bokach, Nadezhda A.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-01-2019; Elsevier Science Ltd
• Subjects: Bonding; Chemical compounds; Coordination compounds; Copper; Copper compounds; Copper(I); Density distribution; Dialkylcyanamide ligands; Dichloromethane; Differential thermal analysis; Differential thermogravimetric analysis; Diffraction; Electron density; Fourier transforms; Ionization; Ligands; NBO analysis; NMR; Nuclear magnetic resonance; Organic chemicals; QTAIM method; Single crystals; Thermogravimetry; Tris-pyrazolylmethane complexes; X ray spectra; X-ray diffraction; Copper(I); Dialkylcyanamide ligands; Tris-pyrazolylmethane complexes; QTAIM method; NBO analysis
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/j.ica.2018.09.024

Eight examples of mononuclear dialkylcyanamide complexes were synthesized and the nature of the M-NCNR2 bond was studied using QTAIM method and NBO analysis.
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•Eight examples of mononuclear dialkylcyanamide complexes [Cu{HC(3,5-Me2pz)3}(NCNR2)][BF4].•X-ray diffraction Structure of [Cu{HC(3,5-Me2pz)3}(NCNC5H10)][BF4].•Comparison of the nature of CuN and CuC coordination bonds using QTAIM method and NBO analysis.
The complexes [Cu{HC(3,5-Me2pz)3}(NCNR2)][BF4] (1–8; R2 = Me21, Et22, C5H103, C4H8O 4, C4H85, C3H6C6H4 [NC3H6C6H4 is 1,2,3,4-dihydroisoquinoline-2-yl] 6, (CH2Ph)27, (Me)Ph 8) were prepared by the reaction of [Cu(NCMe)4][BF4] with HC(3,5-Me2pz)3 and NCNR2 (CH2Cl2, 20–25 °C) and these species were characterized by C, H, N analyses, high resolution mass-spectrometry with electrospray ionization, 1H, 13C{1H} NMR and FTIR spectroscopic techniques, molar conductivity measurements, thermogravimetry/differential thermal analysis, and also by single-crystal X-ray diffraction for 3. The theoretical topological analysis of the electron density distribution (QTAIM method) together with the NBO analysis were applied to study the nature of CuN and CuC coordination bonds in [Cu{HC(3,5-Me2pz)3}(NCNMe2)]+, [Cu{HC(3,5-Me2pz)3}(NCMe)]+, and [Cu{HC(3,5-Me2pz)3}(CNMe)]+ model species. The nature of CuN coordination bonds in [Cu{HC(3,5-Me2pz)3}(NCNMe2)]+ and [Cu{HC(3,5-Me2pz)3}(NCMe)]+ is very similar, whereas CuC contact in [Cu({HC(3,5-Me2pz)3}(CNMe)]+ is relatively more covalent. The calculated vertical total energies for the CuN and CuC coordination bonds cleavage increase in the following row: [Cu{HC(3,5-Me2pz)3}(NCMe)]+ (36 kcal/mol) < [Cu{HC(3,5-Me2pz)3}(NCNMe2)]+ (41 kcal/mol) < [Cu{HC(3,5-Me2pz)3}(CNMe)]+ (47 kcal/mol), and these theoretical data are coherent with the experimental observations.