Abstract

M. L. Sehgal¹ and Irshad Ahmad²

DOI : http://dx.doi.org/10.13005/ojc/330416

D F T implemented in ADF.2012.01 was used to study the structures of 8 macro cyclic paramagnetic four coordinate D_2d complexes:[Phen₂M]²⁺ {M= Mn (II), Fe(II), Co(II),Ni(II)(II),Cu(II)};[Phen₂M]³⁺{M=Ti(III)_,V(III),Cr(III)}(Phen=1,10-phenanthroline) by applying  four spectral techniques. After pre-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 TZ2P Basis sets in ESR/EPR/EFG/ZFS Program to obtain ESR parameters: g₁₁, g₂₂, g₃₃, g_iso, a₁₁, a₂₂, a₃₃, A _ten. More ESR parameters (g_n. A _ten, ZFS) and NQR parameters {h, q₁₁, q₂₂, q₃₃, NQCC} were obtained on replacing Spin Orbit by scalar command in a new ADF Input. The “NMR Program” with Single Point, LDA, Default, None, Collinear, Nosym using DZ or TPZ 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 the  σ values of the constituents. The software was, then, run with Frequencies to obtain IR frequencies of normal modes of each of 129 fundamental vibration bands of the complexes. Importance of the study would lie in the fact that: (i) 5 parameter: σ, δ,h, g_n .A _ten, NQCC of ¹⁴N; 4 parameters: σ, δ, g _n. A _ten, h  of ¹³C and 3 parameters: σ, δ, g. A _ten of ¹H corroborated to infer that in all these complexes, the 24 C were of 6 types; the16 H of 4 types and all the 4 N were spatially of the same type(ii) it confirmed MLCT phenomenon by NMR(iii)  calculated another parameter of each of NMR (H^) and ESR {ΔE_hf} and two of NQR {h,Laplace equation} (iv) classified129 bands into vibration symmetries and IR activities and (iv) gave  thermal parameters of the complexes.

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

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