Synthesis, X-ray structures and NIR chiroptical properties of a series of dinuclear lanthanide(iii) complexes [Ln₂{μ-(S- or RS-pba)}₄(HBpz₃)₂]; novel configurational chirality due to non-bonding Ln⋯O interactions

Novel Configurational Structures of Sodium Tetrakis(3-heptafluorobutylryl-(+)-camphorato) Ln(III) Complexes with a Trapped Na+ by Na+···FC Interactions in the Solid State and in Solution

“…Recently, much attention has been paid to lanthanide complexes from the viewpoint of luminescence as light sources or chemical sensing, biological applications or chiral catalysis, and molecular magnetism. − Configurational chirality of polyhedral stereochemistry around the Ln ion provides fundamental information to reveal lanthanide ion recognition and chiral sensing of biological substrates on the basis of specific spectra−structure relationships in view of the lability or Ln ion size and coordination number. − Chiral macrocyclic tetramine tetracarboxylate octadentate ligands ‘dota' , or helical noncovalent d−f tripodes 8a-c or terdentate chiral ligands 8d result in diastereoselective formation of structurally robust configurational chiral lanthanide complexes, even in solution. We have studied the 3d−4f heterometal dinuclear complexes where the steric control around labile lanthanide ions was realized by intramolecular interactions. , Afterward, unique stereospecific consequences in the tetrakis(μ-( S )-phenylbutylato- k 2 O) dinuclear Ln−Ln complexes were found through weak Ln···O interactions between one Ln ion and the coordinated oxygen at the other Ln ion . On the other hand, the chiral β-diketonate didentate ligands such as (+)-hfbc(3-heptafluorobutylryl-(+)-camphorate) or (+)-tfac(3-trifluoroacetyl-(+)-camphorate) (Chart ) give labile Ln complexes of which the solution structures were not well characterized, , although [Eu((+)-hfbc or -tfac) 3 ] has been extensively utilized for chiral discrimination by NMR or circular dichroism (CD).…”

“…9,10 Afterward, unique stereospecific consequences in the tetrakis(µ-(S)-phenylbutylato-k 2 O) dinuclear Ln-Ln complexes were found through weak Ln‚‚‚O interactions between one Ln ion and the coordinated oxygen at the other Ln ion. 11 On the other hand, the chiral β-diketonate didentate ligands such as (+)-hfbc(3-heptafluorobutylryl-(+)camphorate) or (+)-tfac(3-trifluoroacetyl-(+)-camphorate) (Chart 1) give labile Ln complexes of which the solution structures were not well characterized, 12,13 although [Eu((+)hfbc or -tfac) 3 ] has been extensively utilized for chiral discrimination by NMR or circular dichroism (CD). There has been no study on [Ln((+)-hfbc) 4 ] -, which is expected to take a stereospecifical chiral configuration, owing to bulky steric requirement as suggested for [Eu((+)-hfbc or (+)tfac) 3 (dmso)] by the CPL study 12 and unidentified [Eu((+)tfac) 4 ]used for NMR shift reagents.…”

Structural comparison in a series of 3,5-bis(2-pyridyl)pyrazolato bridged Ln(III)–Cr(III) dinuclear complexes

“…It is noted that the Ln· · ·O4 distance also reflects the increasing tendency of the CN with increasing the Ln III ion size as if there were an attractive force between Ln and O4. The analogous situation is encountered for [(HBpz 3 )Ln(-RS-pba) 4 Ln(HBpz 3 )] [5]. In this case, there is found the shortening of the Ln· · ·O nonbonding distance which is associated with increase of CN from 7 to 8 together with increasing ionic radius of Ln(III).…”

“…In addition, the structural variations of macrocyclic Ln III (DOTA) complexes were demonstrated by Bombieri and co-workers [3]. In our recent study, only subtle polyhedral change in a series of [Ln(hfac) 3 (IM2py)] was reported [4], whereas polyhedral variation with CN change from 7 to pseudo 8 was discovered in a series of 4f-4f dinuclear complexes [(HBpz 3 )Ln(-pba) 4 Ln(HBpz 3 )](pba = S-and R-phenylbutyrate) [5]. On the other hand, the 3d-4f heteropolymetallic complexes has been extensively studied to improve physicochemical properties with much interest [6].…”