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A frustrated Lewis pair of dititanoxycarbene [(Ti(N[tBu]Ar)3)2(μ-CO2)] (Ar = 3,5-Me2C6H3) and B(C6F5)3 cleaved dihydrogen under ambient conditions to give the zwitterionic formate [(Ti(N[tBu]Ar)3)2(μ-OCHO-ηO:ηO′)(B(C6F5)3)] and the hydrido borate [Ti(N[tBu]Ar)3][HB(C6F5)3]. [ABSTRACT FROM AUTHOR]

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]

An important challenge in the artificial fixation of N2 is to find atom efficient transformations that yield value-added products. Here we explore the coordination complex mediated conversion of ubiquitous species, CO and N2, into isocyanate. We have conceptually split the process into three steps: (1) the sixelectron splitting of dinitrogen into terminal metal nitrido ligands, (2) the reduction of the complex by two electrons with CO to form an isocyanate linkage, and (3) the one electron reduction of the metal isocyanate complex to regenerate the starting metal complex and release the product. These steps are explored separately in an attempt to understand the limitations of each step and what is required of a coordination complex in order to facilitate a catalytic cycle. The possibility of this cyanate cycle was explored with both Mo and V complexes which have previously been shown to perform select steps in the sequence. Experimental results demonstrate the feasibility of some of the steps and DFT calculations suggest that, although the reduction of the terminal metal nitride complex by carbon monoxide should be thermodynamically favorable, there is a large kinetic barrier associated with the change in spin state which can be avoided in the case of the V complexes by an initial binding of the CO to the metal center followed by rearrangement. This mandates certain minimal design principles for the metal complex: the metal center should be sterically accessible for CO binding and the ligands should not readily succumb to CO insertion reactions. [ABSTRACT FROM AUTHOR]

Crystallization of Na2VOP2O7 from its aqueous solution results in formation of a one-dimensional inorganic polymer {Na2VO(H2O)P2O7·7H2O}n (1). When this polymer is dehydrated at elevated temperatures this polymer undergoes a phase transition to form the two-dimensional framework β-Na2VOP2O7, which although previously reported had been difficult to access. Exchanging lithium for sodium via ion-exchange chromatography results in formation of a discrete, cyclic, tetramer species, Li8[VOP2O7(H2O) ·4H2O]4 (2). Isolation of crystalline β-Li2VOP2O7 using a dehydration procedure analogous to the one employed for the sodium derivative was unsuccessful. In contrast, we show that β-K2VOP2O7 can be obtained from the amorphous phase K2VOP2O7·nH2O (n = 0-7) upon thermal dehydration. [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 ).