Premium
The Synthesis and Structure of Trimetaphosphimato Complexes of Hafnium and Zirconium
Author(s) -
Stock Norbert,
Herrendorf Wolfgang,
Beck Johannes,
Schnick Wolfgang
Publication year - 1998
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/(sici)1099-0682(199804)1998:4<469::aid-ejic469>3.0.co;2-q
Subject(s) - chemistry , isostructural , zirconium , hafnium , aqueous solution , crystallography , stoichiometry , ion , crystal structure , inorganic chemistry , medicinal chemistry , stereochemistry , organic chemistry
The (trimetaphosphimato)hafnates and ‐zirconates Na 4 {Hf 4 (μ 4 ‐O)(μ‐OH) 6 [(PO 2 NH) 3 ] 4 } · 18 H 2 O [ 1 , Pa 3, a = 22.687(3) Å, Z = 8], Na 4 {Hf 4 (μ 4 ‐O)(μ‐OH) 6 [(PO 2 NH) 3 ] 4 } · 21 H 2 O [ 2 , R 3, a = 14.350(2), c = 50.348(10) Å, Z = 6], Na 4 {Zr 4 (μ 4 ‐O)(μ‐OH) 6 [(PO 2 NH) 3 ] 4 } · 18 H 2 O [ 3 , Pa 3, a = 22.693(3) Å, Z = 8], and Na 4 {Zr 4 (μ 4 ‐O)(μ‐OH) 6 [(PO 2 NH) 3 ] 4 } · 21 H 2 O [ 4 , R 3¯, a = 14.303(2), c = 50.284(10) Å, Z = 6] were obtained by the stoichiometric reaction of HfOCl 2 · 8 H 2 O and ZrOCl 2 · 8 H 2 O with an aqueous solution of Na 3 (PO 2 NH) 3 · 4 H 2 O, followed by the diffusion‐controlled addition of methanol. During these reactions compounds 1 and 2 , or 3 and 4 , crystallized simultaneously and the hafnium and zirconium complexes 1 and 3 , as well as 2 and 4 , were found to be isostructural and isomorphous. The characteristic structural feature which is central to 1 , 2 , 3 , and 4 is the complex tetranuclear anion {M 4 (μ 4 ‐O)(μ‐OH) 6 [(PO 2 NH) 3 ] 4 } 4− with M = Zr or Hf. The anion consists of five corner‐sharing adamantanoid cages. The central cage, {M 4 (μ 4 ‐O)(μ‐OH) 6 } 8+ , has a tetracoordinated oxygen atom in the middle, and the other cages are formed by the trimetaphosphimate ions acting as tridentate ligands which coordinate to Hf or Zr. The water content of the compounds 1−4 could not be determined unequivocally by chemical analyses since the compounds are always obtained as mixtures of the rhombohedral ( 2 / 4 ) and cubic ( 1 / 3 ) phases. Thermal decomposition of compounds 1 − 4 starts above 120°C and leads to the formation of HfP 2 O 7 and ZrP 2 O 7 /NaZr 2 (PO 4 ) 3 , with the evolution of H 2 O and NH 3 . DSC measurements gave no evidence that the compounds 1 and 2, or 3 and 4 , might be transformed into each other by heating.