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Binding of dinitrogen (N

A series of possible precursors for generating C2 with the general formula Me3E–C2–I(Ph)FBF3 [E = C (1), Si (2), and Ge (3)] has been theoretically investigated using quantum chemical calculations. The equilibrium geometries of all species show a linear E–C2–I+ backbone. The inspection of the electronic structure of the Me3E–C2 bond by energy decomposition analysis coupled with the natural orbital for chemical valence (EDA-NOCV) method suggests a combination of electron sharing C–C σ-bond and v weak π-dative bond between Me3C and C2 fragments in the doublet state for species 1 (E = C). For species 2 (Si) and 3 (Ge), the analysis reveals σ-dative Me3E–C2 bonds (E = Si, Ge; Me3E←C2) resulting from the interaction of singly charged (Me3E)+ and (C2–IPh(BF4))− fragments in their singlet states. The C2–I bond is diagnosed as an electron sharing σ-bond in all three species, 1, 2 and 3.

Dinitrogen (N2) binding and its activation have been achieved by non-metal compounds like intermediate cAACborylene with the general formula of (cAAC)2(B-Dur)2(N2) [cAAC = cyclic alkyl(amino)carbene; Dur = aryl group, 2,3,5,6-tetramethylphenyl; B-Dur = aryl-borylene].

Fluorescent diarylchlorostibane, distibane are utilized as precursors for syntheses of redox-active dimeric/trimeric alkali-metal antimonides by reductive dehalogenation. DFT and EDA-NOCV analysis are performed to shed light on the electron transfer mechanism.

The binding of the dinitrogen molecule to the metal center is the first and crucial step toward dinitrogen activation. Favorable interaction energies are desired by chemists and biochemists to stud...

The MoFe7S9C1– unit of the nitrogenase cofactor (FeMoco) attracts chemists and biochemists due to its unusual ability to bind aerial dinitrogen (N2) at ambient condition and catalytically convert i...

Two new series of air stable compounds of cAACX=fluorene/indene (X = Me2, Et2, Cy) [cAAC = cyclic (alkyl) amino carbene] have been isolated and well characterized by single-crystal X-ray single crystal diffraction, photoluminescence, cyclic voltammogram (CV) and electron paramagnetic spectrum (EPR) studies. Fluorescence studies reveals green light emission of cAAC coordinated Fluorene, whereas free Fluorene generally shows a violet emission. Interestingly, the sterically crowded fluorene analogue display solvatochromism and CF3CO2H sensing in solution. CV of the compounds show a quasi-reversible feature, indicating the functionalization of fluorene/indene with radical anionic form of carbene, confirmed by CV/EPR measurements. DFT/TDDFT calculations and energy decomposition analysis coupled with natural orbital for chemical valence (EDA-NOCV) have been carried out to study different aspects of bonding and electronic transitions. Such a class of redox active and thermally stable organic molecules is suitable for molecule based spin memory devices.

The factors/structural features which are responsible for the binding, activation and reduction of N

Metal ions-based inorganic-organic hybrid composites are often reported acting as good to excellent catalysts with various substrate scopes under milder reaction conditions. The active catalyst of a catalytic cycle is sometimes proposed to be a short-lived reactive intermediate species. A three coordinate (L-Me)Ni(II) intermediate species [L-Me=O

The FeVco cofactor of nitrogenase (VFe

The stability and bonding of a series of hetero-diatomic molecules with general formula (cAAC)EM(CO)n , where cAAC = cyclic alkyl(amino) carbene; E = group 14 elements (C, Si, and Ge); M = transition metal (Ni, Fe, and Cr) have been studied by quantum chemical calculations using density functional theory (DFT) and energy decomposition analysis-natural orbital chemical valence (EDA-NOCV). The equilibrium geometries were calculated at the BP86/def2-TZVPP level of theory. The tri-coordinated group 14 complex (1a, 4a, and 7a) in which one of the CO groups is migrated to the central group 14 element from adjacent metal is theoretically found to be more stable when the central atom (E) is carbon. On the other hand, the two-coordinate group 14 element containing metal-complexes (2, 5, 8, 3, 6, and 9) are found to be more stable with their corresponding heavier analogues. The electronic structures of all the molecules have been analyzed by molecular orbital, topological analysis of electron density and natural bond orbital (NBO) analysis at the M06/def2-TZVPP//BP86/def2-TZVPP level of theory. The nature of the cAACE and EM bonds has been studied by EDA-NOCV calculations at BP86-D3(BJ)/TZ2P level of theory. The EDA analysis suggests that the bonding of cAACC(CO) can be best represented by electron sharing σ and π interactions, whereas, C(CO)M(CO)n-1 by dative σ and π interactions. On the other hand, EDA-NOCV calculations suggests both dative σ and π interactions for cAACE and EM(CO)n bonds of the corresponding Si and Ge analogues having stronger σ- and relatively weaker π-bonds. The topological analysis of electron density supports the closed-shell interaction for the Si and Ge complexes and open-shell interaction for the carbon complexes. The calculated proton affinity and hydride affinity values corroborated well with the present bonding description. This class of complexes might act as efficient future catalysts for different organic transformations due to the presence of electron rich group 14 element and metal carbonyl.

Syntheses of the copper and gold complexes [Cu{Fe(CO)5}2][SbF6] and [Au{Fe(CO)5}2][HOB{3,5‐(CF3)2C6H3}3] containing the homoleptic carbonyl cations [M{Fe(CO)5}2]+ (M=Cu, Au) are reported. Structural data of the rare, trimetallic Cu2Fe, Ag2Fe and Au2Fe complexes [Cu{Fe(CO)5}2][SbF6], [Ag{Fe(CO)5}2][SbF6] and [Au{Fe(CO)5}2][HOB{3,5‐(CF3)2C6H3}3] are also given. The silver and gold cations [M{Fe(CO)5}2]+ (M=Ag, Au) possess a nearly linear Fe‐M‐Fe’ moiety but the Fe‐Cu‐Fe’ in [Cu{Fe(CO)5}2][SbF6] exhibits a significant bending angle of 147° due to the strong interaction with the [SbF6]− anion. The Fe(CO)5 ligands adopt a distorted square‐pyramidal geometry in the cations [M{Fe(CO)5}2]+, with the basal CO groups inclined towards M. The geometry optimization with DFT methods of the cations [M{Fe(CO)5}2]+ (M=Cu, Ag, Au) gives equilibrium structures with linear Fe‐M‐Fe’ fragments and D 2 symmetry for the copper and silver cations and D 4d symmetry for the gold cation. There is nearly free rotation of the Fe(CO)5 ligands around the Fe‐M‐Fe’ axis. The calculated bond dissociation energies for the loss of both Fe(CO)5 ligands from the cations [M{Fe(CO)5}2]+ show the order M=Au (D e=137.2 kcal mol−1)>Cu (D e=109.0 kcal mol−1)>Ag (D e=92.4 kcal mol−1). The QTAIM analysis shows bond paths and bond critical points for the M−Fe linkage but not between M and the CO ligands. The EDA‐NOCV calculations suggest that the [Fe(CO)5]→M+←[Fe(CO)5] donation is significantly stronger than the [Fe(CO)5]←M+→[Fe(CO)5] backdonation. Inspection of the pairwise orbital interactions identifies four contributions for the charge donation of the Fe(CO)5 ligands into the vacant (n)s and (n)p AOs of M+ and five components for the backdonation from the occupied (n‐1)d AOs of M+ into vacant ligand orbitals., Donation of an electron pair from the HOMO of [Fe(CO)5]2 to the 4s LUMO of Cu+ giving the (+,+) component of the Fe‐Cu‐Fe σ bond in [Cu{Fe(CO)5}2]+. The associated charge flow with the direction red→blue is given by the deformation density.

Quantum chemical calculations using density functional methods were performed for complexes of type L2C2 with L = NHCMe (1), SNHCMe (2) (S = saturated), cAACMe (3), and diamidocarbene (DACMe) (4). ...

The syntheses of the two novel complexes [Ag{Mo/W(CO)6}2]+[F‐{Al(ORF)3}2]− (RF=C(CF3)3) are reported along with their structural and spectroscopic characterization. The X‐ray structure shows that three carbonyl ligands from each M(CO)6 fragment bend towards the silver atom within binding Ag−C distance range. DFT calculations of the free cations [Ag{M(CO)6}2]+ (M=Cr, Mo, W) in the electronic singlet state give equilibrium structures with C 2 symmetry with two bridging carbonyl groups from each hexacarbonyl ligand. Similar structures with C 2 symmetry (M=Nb) and D 2 symmetry (M=V, Ta) are calculated for the isoelectronic group 5 anions [Ag{M(CO)6}2]− (M=V, Nb, Ta). The electronic structure of the cations is analyzed with the QTAIM and EDA‐NOCV methods, which provide detailed information about the nature of the chemical bonds between Ag+ and the {M(CO)6}2 q (q = −2, M = V, Nb, Ta; q = 0, M = Cr, Mo, W) ligands., Hexacarbonyls as ligands: The molecules M(CO)6 (M=Mo, W) act as ligands towards the silver ion, giving the title compounds [Ag{M(CO)6}2]+[F‐{Al(ORF)3}2]− (RF=C(CF3)3). Their structures and bonding have been analyzed and compared with those of the very recently prepared isoelectronic complexes [Ag{M(CO)6}2]− (M=Nb, Ta).

Quantum chemical studies using density functional theory and ab initio methods have been carried out for the molecules L‐C3‐L with L=PPh3 (1), NHCMe (2, NHC=N‐heterocyclic carbene), and cAACMe (3, cAAC=cyclic (alkyl)(amino) carbene). The calculations predict that 1 and 2 have equilibrium geometries where the ligands are bonded with rather acute bonding angles at the linear C3 moiety. The phosphine adduct 1 has a synclinal (gauche) conformation whereas 2 exhibits a trans conformation of the ligands. In contrast, the compound 3 possesses a nearly linear arrangement of the carbene ligands at the C3 fragment. The bond dissociation energies of the ligands have the order 1, C3 stabilization: Quantum chemical studies using density functional theory and ab initio methods have been carried out for the molecules L‐C3‐L with L=PPh3 (1), NHCMe (2, NHC=N‐heterocyclic carbene), and cAACMe (3, cAAC= cyclic (alkyl)(amino) carbene). The calculations predict that 1 and 2 have equilibrium geometries where the ligands are bonded with rather acute bonding angles at the linear C3 moiety.