59Co NMR, a facile tool to demonstrate EEE, EEZ, EZZ and ZZZ configurational isomerism in fac-[Co(L-κS,O)3] complexes derived from asymmetrically substituted N,N-dialkyl-N′-aroylthioureas

Cobalt(III) Metallacryptates and Their Guest Cation-Exchange in Solution Monitored by 59Co NMR

“…This fact is demonstrated by a recent report in which 59 Co NMR spectroscopy was successfully utilized to study several tris cobalt(III) complexes derived from asymmetrically substituted aroylmono(thioureas). 17,30 The technique therefore is expected to be an ideal spectroscopic probe for the study of the [M ⊂ {Co 2 (L cat ) 3 }](PF 6 ) (M + = Cs + , Rb + , K + , or NH 4 + ) metallacryptates described in this paper. In view of the high sensitivity of the 59 Co NMR chemical shifts to factors such as temperature, concentration, and solvent, a sample of the simple tris(benzoyl-N,N-diethylthioureato)cobalt(III) complex ( fac- + -inclusion compound, the 59 Co NMR shielding trend appears to be related to the decrease in the relative ionic radii of the guest alkaline metal ions from Cs + to K + .…”

“…14−16 Recently, 59 Co NMR spectroscopy has been shown to meet this expectation and to be an excellent tool to study the configurational isomerism of a series of octahedral mononuclear fac-[Co(L-κS,O) 3 ] complexes. 17 Herein we demon-strate that 59 Co NMR spectroscopy is an exceptionally useful method to investigate small perturbations to the octahedral coordination sphere of Co(III) centers in [M ⊂ {Co 2 (L cat ) 3 }]-(PF 6 ) (M + = Cs + , Rb + , K, + or NH 4 + ) metallacryptates. Moreover, 59 Co NMR proves to be a unique tool to explore the interesting lability of the guest cation, as well as cation exchange behavior of guest cations in these Co(III) containing metallacryptates.…”

“…This expectation follows from the high NMR receptivity of the 59 Co nucleus ( I = 7/2), its large chemical shift range, which is sensitive inter alia to the structure of the coordinating ligand, the solvent composition, and temperature. − Recently, 59 Co NMR spectroscopy has been shown to meet this expectation and to be an excellent tool to study the configurational isomerism of a series of octahedral mononuclear fac -[Co­(L-κ S,O ) 3 ] complexes . Herein we demonstrate that 59 Co NMR spectroscopy is an exceptionally useful method to investigate small perturbations to the octahedral coordination sphere of Co­(III) centers in [M ⊂ {Co 2 (L cat ) 3 }]-(PF 6 ) (M + = Cs + , Rb + , K, + or NH 4 + ) metallacryptates.…”

Synthesis, characterization, DNA binding, topoisomerase inhibition, and apoptosis induction studies of a novel cobalt(III) complex with a thiosemicarbazone ligand

“…In terms of the metal center in complex 4, transition metal NMR chemical shifts are useful probes of the structure and reactivity of many coordination complexes since those chemical shifts allow for tiny variations at the coordination metal center under investigation [184]. It is known that the isotope 59 Co exhibits the largest known shielding range, spanning some 18,000 ppm or more [185][186][187]. It is also 100% naturally abundant, possesses a relatively high magnetogyric ratio [188], and by virtue of the magnetic mixing of its occupied and excited d orbitals, it may experience substantial paramagnetic deshielding (> 15,000 ppm) that will reveal subtle changes in the chemical environment of a cobalt metal center [187,188].…”

Recent trends in chemistry, structure, and various applications of 1-acyl-3-substituted thioureas: a detailed review

“…Octahedral diamagnetic complexes 69a–j of substituted thiourea ligands and cobalt metal were synthesized by Barnard et al 54 The synthesis of complexes 69a–j involves the reaction between ligand 68 and CoCl 2 ·6H 2 O in ethanol at room temperature Scheme 20 . These complexes were completely characterized by using 1 H, 13 C and 59 Co NMR into configurational isomers, and the research group also reported the crystal structures of some of the isolated forms.…”