958229-53-3Relevant academic research and scientific papers
Neutral bis(1,4-diaza-1,3-butadiene)nickel complexes and their corresponding monocations: Molecular and electronic structures. A combined experimental and density functional theoretical study
Muresan, Nicoleta,Weyhermueller, Thomas,Wieghardt, Karl
, p. 4390 - 4398 (2008/03/13)
The reaction of 2 equivalents of 2-methyl-1,4-bis(2,6-dimethylphenyl)-1,4- diaza-1,3-butadiene, (1LOx)0, or 2-methyl-1,4-bis(2,6-diisopropylphenyl)-1,4-diaza-1,3-butadiene, ( 2LOx)0, in diethyl ether or n-hexane with 1 equivalent of Ni(cdt) where (cdt)0 is the ligand cyclododecatriene affords dark red, diamagnetic precipitates of [NiII( 1L)2] (1) and of [NiII(2L) 2] (3). The ligands (1L)1- and ( 2L)1- are the one-electron reduced, monoanionic π radicals of the above neutral 1,4-diaza-1,3-butadienes. 1 and 3 have been structurally characterized by X-ray crystallography; both possess a distorted tetrahedral geometry where the dihedral angle between the two metallacycles Ni-N-C-C-N is 47.9° and 53°, respectively, ( = 0° for square planar and 90° for a regular tetrahedral geometry). The reaction of 1 and 3 with 1 equivalent of ferrocenium hexafluorophosphate gives the paramagnetic (S t = 1/2) complexes 2 and 4, respectively: [NiI( 1LOx)2](PF6) (2), [Ni I(2LOx)2](PF6) (4). Their EPR spectra indicate the presence of a central Ni(i) ion (d9; S Ni = 1/2). Thus, the one-electron oxidation of 1 and 3 by [Fc]PF 6 induces an intramolecular one-electron reduction of the central Ni ion and a concomitant one-electron oxidation of the second π radical (L) 1- → (LOx)0 + e. Broken symmetry DFT calculations (B3LYP) corroborate the correctness of the electronic structure descriptions of 1-4. The reaction of (1LOx)0 with NiI2 (1: 1) in tetrahydrofuran yields tetrahedral [Ni II(1LOx)I2] (5) with an S t = 1 ground state. The Royal Society of Chemistry.
