Theoretical study on second hyperpolarizabilities of singlet diradical square planar nickel complexes involving o-semiquinonato type ligands.
Hybrid density functional theory method is applied for investigating the diradical character dependence of the second hyperpolarizability (gamma) of square planar nickel complexes involving several types of bidentate ligands [o-C6H4XY, where X = Y = O, NH, S, Se, and PH as well as (X, Y) = (NH, NH2) and (S, NH2)]. It is found that, as a function of the donor atoms, the diradical character of these complexes varies from 0.0 to 0.884 and is associated with substantial variations of gamma ranging from 14 x 10(3) to 819 x 10(3) au. In particular, the largest gamma values are associated with intermediate diradical characters in good agreement with the structure-property relationship obtained for pure hydrocarbon systems. Increasing the electronegativity of the X and Y donor groups of the ligands leads to larger diradical characters as a result of the enhancement of the double bond nature of the C=X(Y) bonds, which further stabilizes the diradicals on both-end benzene rings. This demonstrates that the electronegativities of the donor atoms of the ligands become a tuning parameter of the diradical character and then of the gamma values of these complexes.
Fukui
Hitoshi
H
Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
Kishi
Ryohei
R
Minami
Takuya
T
Nagai
Hiroshi
H
Takahashi
Hideaki
H
Kubo
Takashi
T
Kamada
Kenji
K
Ohta
Koji
K
Champagne
Benoît
B
Botek
Edith
E
Nakano
Masayoshi
M
D000465:Algorithms; D005609:Free Radicals / Q000737:chemistry*; D008024:Ligands; D008962:Models, Theoretical; D015394:Molecular Structure; D009532:Nickel / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D011789:Quantum Theory; D011809:Quinones / Q000737:chemistry*
D005609:Free Radicals; D008024:Ligands; D009942:Organometallic Compounds; D011809:Quinones; D009532:Nickel