NMR, ESR, NQR and IR Studies of Paramagnetic Macrocyclic Complexes of 1st Transition Series Metal Ions Exhibiting MLCT Phenomenon: A DFT Application. Part: III. Tris (2, 2- bipyridine) Complexes

Abstract

DFT implemented in ADF.2012.01 was applied to study the structures of three macrocyclic paramagnetic hexa coordinate complexes: [L3M] 2+ {M=V(II), Ni(II)}, and [L3Cr] 3+ (L=2,2  -bipyridine) by four spectral techniques. After their pre-optimization, the software was run by using Single Point, LDA, Default, Relativity, Spin Orbit, ZORA, Unrestricted, None, Collinear, Nosym using TZP or TZ2P Basis sets in ESR/EPR/EFG/ZFS Program to obtain ESR parameters: g11, g22, g33, giso, a11, a22, a33, Aten. More ESR parameters (gn. Aten, ZFS) and NQR parameters {, q11, q22, q33, NQCC} were obtained by replacing Spin Orbit by scalar command in a new ADF Input. The software was, then, run using the “NMR Program” with Single Point, Default, None, Collinear, Nosym using the same Basis sets leaving unrestricted command blank to obtain Shielding Constants (σM, σ 13 C, σ 17 O), Chemical Shifts (δM, δ 13 C, δ 17 O), two diamagnetic, four paramagnetic and four spin orbit contributing terms in σ values of the constituents. The software was also run to obtain IR frequencies of normal modes of the (3n-6) fundamental vibration bands of the complexes. Five parameters: σ, δ, g.Aten, , NQCC of 14 N; four parameters: σ, δ, g.Aten,  of 13 C and three parameters: σ, δ, g.Aten, of 1 H corroborated to infer that the 30 Carbons were of 5 different types, the 24 Hydrogens were of 4 different types but the 6 Nitrogens were of the same type spatially in the three studied complexes. This study was important because we could confirm MLCT phenomenon by NMR; calculated four more NMR, ESR and NQR parameters: H^, Ehf, Asymmetric coefficient (), Laplace equation; classified the 177 bands into their vibration symmetries and IR activities and calculated some thermal parameters of the complexes.