N,N′-bis(substituted-phenyl)oxamides and their dinuclear pentacoordinate nickel(II) complexes

Blocking and bridging ligands direct the structure and magnetic properties of dimers of pentacoordinate nickel(ii)

“…16,[18][19][20][21] In these reactions, the ligands are effectively deprotonated by the μ-hydroxo anion of the precursor complex without the addition of another basic reagent. In recent contributions to this field, we reported the preparation of several mono- 19 and dinuclear 16,18,20,21 The new nickel complexes are air-stable and IR spectra of complexes 1-4 show bands around 2500 ν(B-H) and 1545 ν(C-N) cm −1 characteristic of the corresponding {NiTp*} backbone, 22 in some cases partly overlapped by those absorptions attributed to the incoming ligands (see the Experimental section). The IR spectra of complexes 5 and 6 show the bands assigned to ν(N-H) (∼3300 cm −1 ) and ν(CvN) (∼1660 cm −1 ) of the coordinated macrocycle and strong bands at 840 and 560 cm −1 due to the hexafluorophosphate anion.…”

“…S2 † and 1) the resonance line pattern observed previously for the N 3 -macrocyclic ligands in pentacoordinate nickel complexes. 16,[18][19][20] The eight α-methylene protons are shifted downfield whereas the six β-methylene protons are shifted upfield with regard to the diamagnetic position probably because of the spin polarization mechanism. 26,27 The isotropically shifted 1 H-NMR signals observed for methyl groups (2-Me, 4-Me(a, b)) can be initially assigned by inspection of their peak areas.…”

“…18 Although nickel(II) in an axial symmetry can have a large zero-field splitting, D, the magnetic behavior of nickel(II) dimers closely follows eqn (1) when a relatively strong antiferromagnetic interaction is operative, which makes the consideration of D unnecessary. 29 This is the case for complexes 1-6 for which least-squares analysis of the experimental data using eqn (1) Table 3 for all dinuclear Ni(II) complexes in pentacoordinate environments.…”

“…17 In this context N,N′-bis-(substituted-phenyl)-oxamides were prepared and their dinuclear nickel(II) complexes {[Ni(N 3 -mc)] 2 (µ-oxamidate)}(PF 6 ) 2 were characterized by X-ray crystallography and spectroscopic and magnetic studies. 18 So far, the magnetic properties of oxalate complexes of nickel have been analyzed on the basis of the presence of different types of ancillary ligands which result in different coordination environments: O 6 , N 4 O 2 , N 3 O 2 O, etc. The influence of alkyl or aryl ligands on their magnetic properties has also been studied.…”

New neutral and lipophilic technetium complexes based on a cytectrene moiety: synthesis, characterization and biological evaluation

“…It is noteworthy that using the standard one-step amidation [18], , -bis(methoxyphenyl)ethanediamide side products [19] were observed for the synthesis of 2 and 3 in nonnegligible yield (20%-35%). All the purified ligands were characterised by MS, elemental analysis, proton and carbon NMR spectroscopies, as outlined in Table 1, and presented expected structural features.…”