ASM 2019

Poster (P36)


Observation of First Order Spin-Orbit Coupling in Trigonal Bi-pyramidal Mononuclear NiII Complex

Arup Sarkar1, Gopalan Rajaraman2

1,2Department of Chemistry, IIT Bombay, Powai, Mumbai- 400076, India

 

Replacement of the two Me- groups from the [Ni(MeDABCO)2Cl3]+ complex with H-group results in a perfect D3h[Ni(DABCO)(HDABCO)Cl3] complex which shows a orbitally degenerate ground state. Jahn-Teller distortion is quenched by the strict trigonal symmetry around the NiII centre which displays a huge zero-field splitting of -506 cm-1. Indeed, from the CASPT2/RASSI-SO/SINGLE_ANISO calculations it is revealed that the lowest two ground spin-orbit states are less than 0.1 cm-1 apart where one can treat these two states as S = 1/2pseudospin KDs. The pseudospin Hamiltonian formalism works well here with ab initio computed gx, gy and gz values (0.0, 0.0 and 7.74 respectively) shows an Ising type anisotropy similar to those encountered in lanthanide complexes. The gZZ axes lies exactly along the highest order C3 axis of the molecule. Cantilever Torque Magnetometry (CTM) experiment also reveals a D value of -506 cm-1, which further supports theoretical calculations.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure: CASPT2 computed ground state g-tensor axes of the molecule.

 

References:

 

1) M. Gruden-Pavlović, M. Perić, M. Zlatar and P. Garca-Fernndez, Chem. Sci., 2014, 5, 1453.

2) G. A. Craig, A. Sarkar, C. H. Woodall, M. A. Hay, K. E. R. Marriott, K. V. Kamenev, S. A. Moggach,

E. K. Brechin, S. Parsons, G. Rajaraman and M. Murrie, Chem. Sci., 2018, 9, 1551-1559.

 

 

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