Hexa(isothiocyanato)chromates(III) of Some Yttrium Group Lanthanide(III) and Europium Complexes with Nicotinic Acid: Synthesis and Crystal Structures

High Surface Area of Polyhedral Chromia and Hexagonal Chromium Sulfide by the Thermolysis of Cyclohexylammonium Hexaisothiocyanatochromate(III) Sesquihydrate

“…The bending vibration of the NÀ CÀ S band, δ(NCS), was observed as a strong band at 480 cm À l . [32,33,35,[37][38][39][41][42][43][44][45][46][47][48][49]57,[85][86][87][88] The coordination of hard Cr(III) ion center by the hard N-terminal of thiocyanate ligand is consistent with Pearson's concept of hard and soft acids and bases (HSAB). [34,44,57,85,86] Furthermore, structural studies by single X-ray diffraction confirmed the binding of N-terminal to Cr(III) in [Cr(NCS) 6 ] 3À .…”

“…[34,44,57,85,86] Furthermore, structural studies by single X-ray diffraction confirmed the binding of N-terminal to Cr(III) in [Cr(NCS) 6 ] 3À . [21,[24][25][26][27][28][29][30][31][32][33][34][35][36][37][39][40][41][42][43][44][45][46][47][48][49] The asymmetric stretching vibration of (À NH + 3 ) bonds of cyclohexylammonium cation could be assigned to the strong, broad bands in the range of 3300-3000 cm À l . This red shift in the asymmetric stretching of NÀ H could be due to the positive charge borne by the nitrogen atom and the hydrogen bonding to the water crystallization molecules and to the S-terminals of [Cr(NCS) 6 ] 3À anion.…”

“…[1,4,7,8,11,13,16,[18][19][20] Thiocyanate metal complexes are unusual due to the intrinsic ambidentate nature, bridging ability, and denticity of thiocyanate ligand. [21] Among the thiocyanate metal complexes is the anionic complex of hexaisothiocyanatochromate(III) [Cr-(NCS) 6 ] 3À , which was used broadly to construct various supramolecular structures with either organic cations [22][23][24][25][26][27][28][29][30] or metal cations, [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49] partially, because both of thiocyanate nitrogen and sulfur terminals are hydrogen acceptors when forming hydrogen bonds. [14,20,25,[27][28][29][31][32]…”

“…[24,26,27,30] The metal salts of [Cr(NCS) 6 ] 3À are classified as bimetallic complexes or double complex salts. [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49] They are able to form molecular magnets. [32] They are useful precursors for the synthesis of various functional materials, polymetallic systems, catalysts, nanocomposites, and reversible thermochromic materials.…”

“…[31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49] The [Cr(NCS) 6 ] 3À , as an inert bulky ion, is a precipitating agent for lanthanide ions in organic-aqueous medium. [34][35][36]39,41,42,44,[46][47][48][49] In addition, [Cr(NCS) 6 ] 3À is a very good reagent for the gravimetric analysis of heavy metal ions, such as copper, silver, cadmium, mercury, lead, thallium, and bismuth, in the aqueous medium, even in the microscale range. [50][51][52][53][54][55][56] The thermolysis, under air, of double complex salts of lanthanides, complexed by the neutral ε-caprolactam, and [Cr(NCS) 6 ] 3À results in a mixture of the corresponding lanthanide oxide (Ln 2 O 3 ) and chromia (Cr 2 O 3 ) nanoparticles due to their relatively low temperatures of decomposition.…”