Abstract

M. L. Sehgal¹ and Irshad Ahmad²

DOI : http://dx.doi.org/10.13005/ojc/330616

DFT implemented in ADF.2012.01 was applied to study the structures of 8  macro- cyclic paramagnetic  four coordinate complexes: [Bipy₂M]²⁺ {M= Mn (II), Fe(II),Co(II), Ni(II)_, Cu (II)}, [Bipy₂M]³⁺{M=Ti(III),V(III)} and [Bipy₂V]⁴⁺( Bipy=2,2^/-bipyridine) by using 4 spectral techniques. After optimization of complexes, the software  was run by using Single Point, LDA or GGA, Default, Relativity, Spin Orbit, ZORA, Unrestricted, None, Collinear , Nosym using TZP or TP2Z Basis sets in ESR/EPR/EFG/ZFS Program  to obtain ESR parameters: g₁₁, g₂₂, g₃₃, g_iso; a₁₁, a₂₂, a₃₃, A _ten. ESR parameters (g_n. A _ten, ZFS) and NQR parameters {η, q₁₁, q₂₂, q₃₃, NQCC} were obtained by replacing Spin Orbit by scalar command in a new ADF Input. On  running the “NMR Program” with Single Point,  Default, None, Collinear, Nosym and using the same Basis sets leaving Unrestricted command  blank gave the Shielding Constants (σM ,σ ¹³C,σ ¹⁷O), Chemical Shifts (δ M, δ¹³C, δ¹⁷O),2 diamagnetic ,4 paramagnetic and 4 spin orbit contributing terms in  σ values of  constituents. The software was run with Frequencies to obtain IR frequencies of normal modes of the (3n-6) fundamental vibration bands of complexes. This study was important because: (i) the 5 parameter: σ, δ,η, g_n .A _ten, NQCC of ¹⁴N; 4 parameters: σ, δ, g_n. A _{ten, η}  of ¹³C and 3 parameters: σ, δ, g. A _ten of ¹H corroborated to infer that in  these complexes, the 20 C were of 5 types; the 16 H of 4 types while  the 4 N were spatially of the same type(ii) it confirmed MLCT phenomenon in the complexes by NMR(iii) we calculated another parameter of each of NMR (H^)and ESR {ΔE_{h f} ) and two of NQR {Asymmetric coefficient (η), Laplace equation} (iv) it classified 117 fundamental  bands of each complex into vibration symmetries and IR activities(v) it gave  thermal parameters of the complexes.

Chemical Shift; Total NMR Shielding Tensor; Nuclear Quadrupole Coupling Constant; Effective Spin Hamiltonian; Asymmetric Coefficient

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