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The terminal nitride anion complex [Na][N[triple bond]Nb[(N[[super t]Bu]Ar).sub.3]] ([Na][1], Ar = 3,5-[Me.sub.2][C.sub.6][H.sub.3]) has reacted with C[O.sub.2] to produce the carbamate complex [Na][[O.sub.2]CN[triple bond]Nb[(N[[super t]Bu]Ar).sub.3]]([Na][[O.sub.2]C-1]). The studies have shown that the series of reactions observed have constituted a closed cycle for the conversion of C[O.sub.2] to CO mediated by a terminal nitride anion complex.

The analogous vanadium isocyanate complex (OCN)V[(N[t-Bu]Ar).sub.3] (1-V(NCO)) is prepared to compare its reactivity with that of a niobium(IV) isocyanate complex (OCN)Nb[(N[t-Bu])Ar).sub.3] (1-Nb(NCO)). The studies have shown that CO not only denitrogenates the vanadium(V) nitride anion complex but also has no affinity for the empty coordination site.

This work focuses on nucleophilic activation of CO2 at the anionic terminal oxo titanium tris(anilide) complexes [(Solv)nM][OTi(N[tBu]Ar)3]m with M=Li, Na, K, Mg, MgMe, AlCl2, AlI2; Ar=3,5‐Me2C6H3; Solv=Et2O, THF, 12‐crown‐4, 2,2,2‐cryptand; n, m=1–2. The CO2 binding strength to the terminal oxo ligand of [OTi(N[tBu]Ar)3]− ([1]−) and the stability of the resulting carbonate moiety [O2COTi(N[tBu]Ar)3]− ([2]−) are highly dependent on the Lewis acidity of the countercation. We report herein on CO2 binding as a function of countercation and countercation coordination environment, and comment in this respect on the bottom and upper limits of the cation Lewis acidity. Thermodynamic parameters are provided for oxo complexes with lithium as countercation, that is, [(Et2O)2Li][1] and [(12‐c‐4)Li][1]. CO2 binding: Anionic terminal oxo complexes of bulky titanium tris(anilide) form carbonate complexes with CO2. This reaction is reversible. Temperature and solvent, as well as countercation and its coordination environment are crucial to the stability of the carbonate species. These factors are examined for the countercations Li+, Na+, K+, Mg2+, and Al3+. [ABSTRACT FROM AUTHOR]

Wir beschreiben ein stabiles, isolierbares Dimetalloxycarben [(TiX3)2(μ2-CO2-κ2C,O:κO′)], 5 (X=N-(tert-Butyl)-3,5-dimethylanilid), das NMR-spektroskopischen Studien bei variabler Temperatur zufolge durch fluktuierende μ2-κ2C,O: κ1O′-Koordination des Carben-C-Atoms an beide Ti-Zentren des zweikernigen Komplexes 5 stabilisiert wird. Quantenchemische Rechnungen am unmodifizierten Molekül lassen auf eine höhere Energie von nur +10.5 kJ mol−1 für den μ2-κ1O: κ1O′-Bindungsmodus des freien Dimetalloxycarbens gegenüber dem μ2-κ2C,O:κ1O′-Bindungsmodus des maskierten Dimetalloxycarbens schließen. Der kationische Ausgangskomplex [(TiX3)2(μ2-OCHO-κO:κO′)][B(C6F5)4], 4[B(C6F5)4], mit verbrückendem Formiatliganden wurde einfach mit der starken Base K(N(SiMe3)2) zu 5 deprotoniert. Komplex 5 reagiert glatt mit CO2 zum verbrückten Oxalatkomplex [(TiX3)2(μ2-C2O4-κO:κO′′)], 6, in einer C-C-bindungsbildenden Reaktion, die allgemein für die Oxalatbildung durch reduktive Kupplung von CO2 an niedervalenten Übergangsmetallkomplexen erwartet wird. [ABSTRACT FROM AUTHOR]

We describe the stable and isolable dimetalloxycarbene [(TiX3)2(μ2-CO2-κ2C, O:κO′)] 5, where X=N-(tert-butyl)-3,5-dimethylanilide, which is stabilized by fluctuating μ2-κ2C, O:κ1O′ coordination of the carbene carbon to both titanium centers of the dinuclear complex 5, as shown by variable-temperature NMR studies. Quantum chemical calculations on the unmodified molecule indicated a higher energy of only +10.5 kJ mol−1 for the μ2-κ1 O:κ1O′ bonding mode of the free dimetalloxycarbene compared to the μ2-κ2C, O:κ1O′ bonding mode of the masked dimetalloxycarbene. The parent cationic bridging formate complex [(TiX3)2(μ2-OCHO-κO:κO′)][B(C6F5)4], 4[B(C6F5)4], was simply deprotonated with the strong base K(N(SiMe3)2) to give 5. Complex 5 reacts smoothly with CO2 to generate the bridging oxalate complex [(TiX3)2(μ2-C2O4-κO:κO′′)], 6, in a C–C bond formation reaction commonly anticipated for oxalate formation by reductive coupling of CO2 on low-valent transition-metal complexes. [ABSTRACT FROM AUTHOR]

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We describe the stable and isolable dimetalloxycarbene [(TiX3)2(μ2-CO2-κ2C, O:κO′)] 5, where X=N-(tert-butyl)-3,5-dimethylanilide, which is stabilized by fluctuating μ2-κ2C, O:κ1O′ coordination of the carbene carbon to both titanium centers of the dinuclear complex 5, as shown by variable-temperature NMR studies. Quantum chemical calculations on the unmodified molecule indicated a higher energy of only +10.5 kJ mol−1 for the μ2-κ1 O:κ1O′ bonding mode of the free dimetalloxycarbene compared to the μ2-κ2C, O:κ1O′ bonding mode of the masked dimetalloxycarbene. The parent cationic bridging formate complex [(TiX3)2(μ2-OCHO-κO:κO′)][B(C6F5)4], 4[B(C6F5)4], was simply deprotonated with the strong base K(N(SiMe3)2) to give 5. Complex 5 reacts smoothly with CO2 to generate the bridging oxalate complex [(TiX3)2(μ2-C2O4-κO:κO′′)], 6, in a C–C bond formation reaction commonly anticipated for oxalate formation by reductive coupling of CO2 on low-valent transition-metal complexes. [ABSTRACT FROM AUTHOR]

The article focuses on a research that develops a synthetic cycle for carbon dioxide and carbon monoxide conversion using an anionic niobium nitride complex. It states that derivatization with an electrophile was conducted to determine the reactivity of [Na][O2C-1] while Me-2's solid-state structure was defined through single-crystal X-ray diffraction methods. Results show the potential of ligand-based approaches. It also extends the field of carbon dioxide reduction chemistry.

The boron and aluminium dimers [Me2E(micro-py)]2 [E=B (1); Al (2)] are formed as mixtures of two isomers in which the group 13 centres are coordinated by the bridging 2-py ligands in a cis or trans manner, however, in contrast to previous studies, we find that simply heating the mixtures of these isomers of and gives the more thermodynamically stable (synthetically useful) trans isomers exclusively (the trans isomer being the only product in the case of the gallium analogue ).