Synthesis, oligomerization and catalytic studies of a redox-active Ni₄-cubane: a detailed mechanistic investigation

Abstract

A robust tetrameric nickel complex [Ni4((Oal−)2L-Me)4(s)4] (s = solvent) with cubane-like Ni4O4 core topology identified as the efficient catalyst for the diastereoselective cyclopropanation of aromatic heterocycles.

Electrochemical dinitrogen to ammonia reduction at a nickel(ii) site: an easy access to an air-stable catalyst

“…Complex 1 displays oligomerisation with n = 1 to 8 in non-coordinating polar aprotic solvents. 38 The electrospray ionisation mass spectrometry (ESI-MS) measurements of 1 showed that the predominating oligomers are n = 4, 5, and 6 in acetonitrile/THF. 38 The oligomers of 1 are in equilibrium with each other in the solution.…”

“…38 The electrospray ionisation mass spectrometry (ESI-MS) measurements of 1 showed that the predominating oligomers are n = 4, 5, and 6 in acetonitrile/THF. 38 The oligomers of 1 are in equilibrium with each other in the solution. However, 1 is only isolated as a tetramer in the solid state.…”

“…The tetranuclear complex [((L-Me)Ni) 4 (Sol) 4 ] 1 [sol = solvent, EtOH, H 2 O; H 2 L-Me = diprotic Schiff base ligand] has been isolated in 95% yield from the reaction between NiCl 2 $6H 2 O and H 2 L-Me in the presence of a base. 38 The detailed synthetic procedure of 1 was discussed in the ESI. † The molecular structure of 1 is given in Fig.…”

“…We present a simple tetranuclear Ni( ii )-catalyst 38 1 containing a spencer-type O 2 N donor Schiff base ligand, which can be isolated as a tetrameric oligomer with over 95% yield as a crystalline solid. For artificial N 2 fixation, thiolates are the most preferred ligand choice among the researchers due to the bioinspired FeMo-cofactor, 39,40 though hydrides, 41 nitrides, 42 and phosphines 43 are also known.…”