The crystal structure of caesium oxobisoxalatobisaquoniobate(V) dihydrate, Cs[NbO(C₂O₄)₂(H₂O)₂].H₂O

Abstract

The structure of Cs[NbO(C204)z(HzO)2].2H20 has been determined from three-dimensional X-ray diffractometer data. The crystals are monoclinic with a=6.464(1), b=11.8697(9), c=7.9518(3) /~, fl= 98"911(3)°; the space group is P2t/m. The coordination polyhedron around niobium is a pentagonal bipyramid. The ligands in the equatorial plane are two oxygen atoms from an oxalato group and their mirror-plane related pairs at distances of 2.104 and 2.124 /~, and one water molecule at 2.169 A. The apices of the bipyramid are occupied by the double-bonded oxygen atom and one water molecule at 1.691 and 2.328/~, respectively.

Structural Variety of Niobium(V) Polyoxo Clusters Obtained from the Reaction with Aromatic Monocarboxylic Acids: Isolation of {Nb2O}, {Nb4O4} and {Nb8O12} Cores

“…For each octameric entities A and B, there exist four crystallographic inequivalent niobium atoms, which are octahedrally coordinated to three μ 2 -oxo groups, two carboxyl oxygen atoms belonging to the 2-naphthoate ligand (in bidentate syn-syn bridging mode between two adjacent Nb) and one remaining oxygen atoms from either ethoxy groups or monodentate 2-naphthoate ligand. The NbÀ O oxo bond distances are in the range 1.825(9)-1.967(9) Å for core A and 1.835(7)-1.969(6) Å for core B, whereas the NbÀ O c (from the bidentate 2naphthoate ligand) are in the range 2.092(7)-2.196(10) Å for core A and 2.132(8)-2.175 (11) Å for core B. The bond valence calculations for the twelve μ 2 -oxygen atoms O1 AÀ O6 A and O1BÀ O6B, from the molecules A and B, corresponds to the values range of 2.022-2.122 and 1.979-2.083, respectively, in agreement with the occurrence of an oxo group.…”

Isolation of a Dodecanuclear Polyoxo Cluster {Nb12O21} Showing a Rare Case of Five‐fold Coordinated Niobium(V) Centers with a Square Pyramidal Geometry

“…As far as we know, these hybrids niobium compounds are systematically molecular association and, extended networks have yet to be discovered. In molecular chemistry of hybrid niobium clusters, commercial precursors can be found and can be described as discrete Nb-centered mononuclear unit, precipitated by oxalic acid to give [A][NbO(C2O4)2(H2O)2]xH2O (A = NH4 + [16,17] or Cs + [18] ) or [A]3[NbO(C2O4)3]xH2O (A = NH4 + [19] or Rb + [20] ) salts, which can be further associated using pyridine-based molecules (phenanthroline, bipyridine, etc…) [21] or divalent transition metals complexes with [Zn(bpy)] 2+ , [22] [Co(terpy)] 2+ , [23] [(Fe-Zn)(bpy)] 2+ [24] (bpy = 2,2'-bipyridine, terpy = 2,2':6',2''-terpyridine) and rare-earth cations. [25] Other niobium oxalates have also been isolated in the presence of non-metallic divalent counter cations such as barium in [Ba2(H2O)5][NbO(C2O4)3][HC2O4]H2O [26] or with peroxide groups.…”

Molecular niobium(v) complexes with mononuclear {Nb1} and dinuclear oxo species {Nb2O} connected through aryl di- or tetra-carboxylate linker

“…9 and 10) or Cs + (ref. 11)) or [A] 3 [NbO(C 2 O 4 ) 3 ]· x H 2 O (A = NH 4 + (ref. 12) or Rb + (ref.…”