Carbon Dioxide Fixation by Organolanthanides and Thermal Degradation into Amorphous and Higher Condensed Ln/O/C/N Solids

Abstract

Ammine[tris(cyclopentadienyl)]‐, amido[bis(cyclopentadienyl)]lanthanides, and tris[bis(trimethylsilylamido)]cerium have been studied with respect to CO2 absorption under various reaction conditions. Subsequent thermal treatment of these complexes under gaseous and supercritical CO2 yielded new higher condensed lanthanide Ln/O/C/N solids. IR spectroscopic studies of the CO2‐activated species reveal the formation of various oxonitridocarbonates, in particular carbamates (O2CNH2–), imidocarbonates (O2CNH2–), isocyanates (OCN–), and carbonates (CO32–), which function as multidentate linkers between the lanthanide ions. Thereby, inorganic polymers are formed, which represent single‐source precursors for application in various deposition methods and can therefore be utilized as pre‐organized reagents in solid‐state chemistry. In this context, we report on the structural characterization of one of the molecular precursors [Cp3YbNH3] [reticular pseudomerohedral twin, P21/c, a = 826.8(2), b = 1103.8(2), c = 1482.0(3) pm, β = 101.60(3)°, Z = 4, V = 1309.0(5)·106 pm3]. Crystals of [Cp3YbNH3] appear red, orange, yellow, and dark green depending on the orientation under plane‐polarized light (pleochroism).(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Precursor Approach to Lanthanide Dioxo Monocarbodiimides Ln2O2CN2 (Ln=Y, Ho, Er, Yb) by Insertion of CO2 into Organometallic Ln–N Compounds

“…During our studies on the reactivity of lanthanide amine and amido complexes towards CO 2 , we synthesized a number of O/C/ N-containing precursors. [15] Our studies revealed the formation of amorphous carbamate-containing compounds. The present study corroborates the controllable formation of Ln/ O/C/N-containing single-source precursors by absorption and fixation of CO 2 .…”

Urea Route to Homoleptic Cyanates—Characterization and Luminescence Properties of [M(OCN)2(urea)] and M(OCN)2 with M=Sr, Eu

“…In cyanato complexes, the assignment of O and N atoms from X-ray diffraction data is often ambiguous, especially if the cyanato ligand bridges metal atoms. Assignments shown in Figure 1 gave the lowest R indices and the resulting Eu À O bond (Eu1 À O1: 2.624 (8) ) is slightly shorter than the EuÀN bond (Eu1À N2: 2.662(7) ), which provides support that the N and O atoms have been properly assigned. The Eu atom is coordinated by six cyanato ligands and two urea moieties forming square antiprisms.…”

“…[25] The distance between the adjacent Eu 2 + atoms (Eu1 À Eu1: 3.8969 (8) ) is slightly shorter than the sum of their van der Waals radii. Pure-phase samples (according to powder X-ray diffractometry and FTIR) of [MA C H T U N G T R E N N U N G (OCN) 2 A C H T U N G T R E N N U N G (urea)] have been obtained by the following procedure: A mixture of the corresponding metal and urea with a molar ratio of 1:3 were sealed in evacuated glass ampoules and reacted at 130 8C.…”

Synthesis of Rare Earth (Oxo)nitridocarbonates by Employment of Supercritical Carbon Dioxide, Single‐source Precursor, Solid‐State, and Ion Exchange Reactions

“…During our studies on the reactivity of lanthanide amine and amido complexes towards CO 2 , a number of O/C/Ncontaining precursors was discovered. [23] Carbon dioxide was used as a pre-organized C/O source forming labile carbamate intermediates. These compounds turned out to be excellent starting materials for the synthesis of hitherto unknown species in the system Ln/O/C/N.…”

“…[22] Compared to the rapidly growing field of carbodiimide chemistry other rare earth (oxo)nitridocarbonates such as cyanates, dicyanamides or carbamates have been rarely mentioned in the literature. [23][24][25][26] To avoid formation of the thermodynamically favored binary oxides, carbides and nitrides a varied chemistry of rare earth (oxo)nitridocarbonates is strongly dependent on the development of inventive reaction strategies. Consequently, we have focused on low temperature approaches towards other rare earth (oxo)nitridocarbonates including carbamates, carbodiimides, cyanates, dicyanamides and tricyanomelaminates.…”