The Structure of the Dipolar Bond in the Rare Earth Nitrilotris(Methylene Phosphonate)s with Different Oxygen Coordination Symmetries

Abstract

The electronic structure of 16 complex compounds of RE (Y, La–Tb) with the same ligand – nitrilotris(methylenephosphonic acid) [NTP, N(CH2PO3)3H6] and with different coordination symmetries of the RE atom is investigated. The structure of XP‐spectra of a valence band in this area significantly differs for structures with non‐octahedral O‐coordination of the RE atom, on the one hand, and those with pseudo‐octahedral O‐coordination of the RE atom, on the other hand. In the XP‐spectra of non‐octahedral O‐coordination complexes the O2s‐states have a maximum at EB = 24–26 eV and are poorly overlapped with Ln5p‐states. For pseudo‐octahedral O‐coordination structures a wide strip is observed in the field of EB = 20–28 eV corresponding to an overlap M5p‐ and O2s‐states with formation of internal valence molecular orbitals (IVMO). Apparently, in pseudo‐octahedral O‐coordination structures the arrangement of O atoms agrees with the octahedral symmetry of RE p‐orbitals and leads to the formation of IVMO M5p+O2s.

Magnetic Behavior of Light Lanthanide (La–Tb) in Linear‐Chain Nitrilo‐Tris‐Methylenephosphonates with Different Structures

“…The [Ln NTP H 3 ]·1.5H 2 O (I‐Ln) and [Ln NTP 2 Na 6 H(H 2 O) 10 ]· n H 2 O[Na(H 2 O) 6 ] 2 (II‐Ln) compounds were obtained according to refs. [32,34–39]. The resulting crystals were separated, washed with DMSO, diethyl ether, and dried in air.…”

3d‐metal (Cr to Zn) Nitrilotris(Methylenephosphonate)s with different coordination symmetries: Electronic Structure and Chemical Bond

“…In complexes with pseudo‐octahedral coordination symmetry of oxygen, which is close to the intrinsic symmetry of the Ln5p states, the Ln5p−O2 s overlapping and the contribution of IVMOs to the Ln−O dipolar bond are much higher as compared with complexes with non‐octahedral coordination. This is manifested in the structure of the X‐ray photoelectron spectra and in the Ln−O bond lengths [27] …”

“…The IVMOs Ln5pÀ O2 s make the largest contribution to the structure of the LnÀ O dipolar bond. [24][25][26] It has been shown [27] that the possibility of the formation of IVMOs and, consequently, the structure of the LnÀ O dipolar bond depend on the coordination symmetry of the oxygen atom environment. In complexes with pseudooctahedral coordination symmetry of oxygen, which is close to the intrinsic symmetry of the Ln5p states, the Ln5pÀ O2 s overlapping and the contribution of IVMOs to the LnÀ O dipolar bond are much higher as compared with complexes with nonoctahedral coordination.…”

“…This is manifested in the structure of the X-ray photoelectron spectra and in the LnÀ O bond lengths. [27] The electronic structure and the nature of the MÀ O dipolar bond for 3d metals are usually considered within the framework of the crystal field theory or ligands field theory. [28] The angular overlapping of the M3d and O2p electronic states adequately describes the structure of dipolar bond in the complexes with octahedral coordination corresponding to the intrinsic symmetry of the M3d orbitals.…”

“…In the present work, the method of the parallel isostructural series [27] has been applied and advanced. The comparative analysis of two parallel isostructural series I , II and complex III has been carried out using high‐precision single‐crystal XRD, XPS and FTIR spectroscopies.…”