Carbene-Functionalized Bulky-Cyclopentadiene Rings.

A series of significantly bulky mono- and di-substituted cyclic alkyl-amino carbene (cAAC)- functionalized cyclopentadiene ring (Cp) compounds were synthesized. The functionalization of the Cp ring with cAAC ligands makes them significantly bulkier, while retaining their ligation properties. These compounds display interesting fluorescence properties.

Isolation and characterization of a blue coloured three coordinate Cu(I)-radical complex with an S donor set.

A stable three coordinate Cu(I)-radical complex with an S donor set having the general formula of [Cu(S-NHCH)(SS-NHCS)] (1) was isolated as dark blue needles. Interestingly, this complex possesses a zwitterionic ligand, S-NHCH, which is coordinated to the central Cu(I) ion its S-atom [S-NHCH C4-thiolate functionalized C2-protonated zwitterionic N-hetero cyclic carbene; SS-NHCS˙ NHC-based dithiolene radical anion]. 1 has been structurally characterized by single-crystal X-ray diffraction, and further characterized by UV-vis, IR, XPS, and EPR spectroscopy.

A Spin-Frustrated Azide- and Alkoxide-Bridged Heterobimetallic Mixed-Valence MnMnNi Disc with = 17/2 or 19/2.

Seven-membered homometallic Fe, MnMn coordination clusters were previously reported to be spin-frustrated molecular discs. Herein, a mixed bimetallic and mixed-valence dicationic [MnMnNi(N)(hmp)](NO) () was isolated in pure form without scrambling of Ni/Mn ions. It was structurally characterized by single-crystal X-ray single-crystal diffraction.

Synthesis of SiN/SiS-heterocycles the reactions of a bis-silylene with isocyanate/isothiocyanate molecules.

Reactions of -carborane-fused bis-silylene 1 with isocyanate/isothiocyanate molecules furnished a series of SiN/SiS-heterocycles, which show distinct styles of cyclization and were theoretically studied.

Small molecule activation by sila/germa boryne species.

The inability of p-block elements to participate in π-backbonding restricts them from activating small molecules like CO, H , and so forth. However, the development of the main group metallomimetics became a new pathway, where the main-group elements like boron can bind and activate small molecules like CO and H . The concept of the frustrated Lewis pair, Boron-Boron multiple bonds, and borylene are previously illustrated.

Unveiling the Anomaly of Reduction of Carborane-bis-silylene-Stabilised Silylone/Germylone Leading to Unusual Oxidation of Si /Ge to Si /Ge with EDA-NOCV Analyses.

Researchers have successfully isolated Si /Ge species, termed silylone and germylone, with two lone pairs of electrons on them. These elusive compounds have been stabilised in singlet ground states by using different donor base ligands. Driess et al.

Open shell versus closed shell bonding interaction in cyclopropane derivatives: EDA-NOCV analyses.

Cyclopropane ring is a very common motif in organic/bio-organic compounds. The chemical bonding of this strained ring is taught to all chemistry students. This three-membered cyclic, C ring is quite reactive which has attracted both, synthetic and theoretical chemists to rationalize/correlate its stability and bonding with its reactivity and physical properties over a century.

Dipotassiumtetrachloride-bridged dysprosium metallocenes: a single-molecule magnet.

The present work describes the dynamic magnetic properties of the complex [(Cp)DyIII2ClK]·3.5(CH) (1), synthesized by employing a tri-aryl-substituted cyclopentadienyl ligand (Cp), [4,4'-(4-phenylcyclopenta-1,3-diene-1,2-diyl)bis(methylbenzene) = CpH]. Each Dy(III)-metallocene weakly couples KCl, displaying slow relaxation of magnetization below 14.

Bonding and stability of elusive silaboryne (SiB) and germaboryne (GeB) with donor base ligands.

Stabilizing the exotic chemical species possessing multiple bonds is often extremely challenging due to insufficient orbital overlap, especially involving one heavier element. Bulky aryl groups and/or carbene as ligand have previously stabilized the SiSi, GeGe, and BB triple bonds. Herein, theoretical calculations have been carried out to shed light on the stability and bonding of elusive silaboryne/germaboryne (Si/GeB triple bond) stabilized by donor base ligands ((cAAC)BE(Me)(L); E = Si, L = cAAC , NHC , PMe ; E = Ge, L = cAAC ).

Redox Active cAAC-Fluorene/Indene Systems Displaying Solvatochromism, Green Luminescence and pH Sensing: Functionalization of Fluorenyl/Indenyl Rings with Radical Carbene.

Two new series of air stable compounds of cAAC = fluorene/indene (X = Me , Et , Cy) [cAAC = cyclic (alkyl) amino carbene] have been isolated and well characterized by X-ray single crystal diffraction, photoluminescence, cyclic voltammogram (CV) and electron paramagnetic resonance (EPR) studies. Fluorescence studies reveals green light emission of cAAC bonded fluorene, whereas free fluorene generally displays a violet emission. Interestingly, the sterically crowded cAAC-fluorene analogue display solvatochromism and CF CO H sensing in solution.

Stability and bonding of carbon(0)-iron-N complexes relevant to nitrogenase co-factor: EDA-NOCV analyses.

The factors/structural features which are responsible for the binding, activation and reduction of N to NH by FeMoco of nitrogenase have not been completely understood well. Several relevant model complexes by Holland et al. and Peters et al.

Dinitrogen Binding and Activation: Bonding Analyses of Stable V(III/I)-N-V(III/I) Complexes by the EDA-NOCV Method from the Perspective of Vanadium Nitrogenase.

The FeVco cofactor of nitrogenase (VFeS(CO)C) is an alternative in the molybdenum (Mo)-deficient free soil living azotobacter vinelandii. The rate of N reduction to NH by FeVco is a few times higher than that by FeMoco (MoFeSC) at low temperature. It provides a N source in the form of ammonium ions to the soil.

The Labile Nature of Air Stable Ni(II)/Ni(0)-phosphine/Olefin Catalysts/Intermediates: EDA-NOCV Analysis.

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 N donor dianionic ligand] can bind with short-lived carbene-ester ligands to produce four coordinate Ni(II) species which can act as carbene transfer intermediate under suitable reaction conditions for C-H functionalization and/or cyclopropanation reactions.

Uncovering the hidden reactivity of benzyne/aryne precursors utilized under milder condition: Bonding and stability studies by EDA-NOCV analyses.

Arenes [C H R(TMS)(OTf); also called benzyne/aryne precursors] containing inter-related leaving groups Me Si (TMS) and CF SO (OTf) on the adjacent positions (1,2-position) are generally converted to their corresponding aryne-intermediates via the addition of fluoride anion (F ) and subsequent elimination of TMS and OTf groups. This reaction is believed to proceed via the formation of an anionic intermediate [C H (TMS-F)(OTf)] . The EDA-NOCV analysis (EDA-NOCV = energy decomposition analysis-natural orbital for chemical valence) of over 35 such precursors of varied types have been reported to reveal bonding and stability of C Si and COTf bonds.

Bonding and stability of dinitrogen-bonded donor base-stabilized Si(0)/Ge(0) species [(cAAC-Si/Ge)(N)]: EDA-NOCV analysis.

Recently, dinitrogen (N) binding and its activation have been achieved by non-metal compounds like intermediate cAAC-borylene as (cAAC)(B-Dur)(N) [cAAC = cyclic alkyl(amino) carbene; Dur = aryl group, 2,3,5,6-tetramethylphenyl; B-Dur = borylene]. It has attracted a lot of scientific attention from different research areas because of its future prospects as a potent species towards the metal free reduction of N into ammonia (NH) under mild conditions. Two (cAAC)(B-Dur) units, each of which possesses six valence electrons around the B-centre, are shown to accept σ-donations from the N ligand (B ← N).

EDA-NOCV analysis of carbene-borylene bonded dinitrogen complexes for deeper bonding insight: A fair comparison with a metal-dinitrogen system.

Binding of dinitrogen (N ) to a transition metal center (M) and followed by its activation under milder conditions is no longer impossible; rather, it is routinely studied in laboratories by transition metal complexes. In contrast, binding of N by main group elements has been a challenge for decades, until very recently, an exotic cAAC-borylene (cAAC = cyclic alkyl(amino) carbene) species showed similar binding affinity to kinetically inert and non-polar dinitrogen (N ) gas under ambient conditions. Since then, N binding by short lived borylene species has made a captivating news in different journals for its unusual features and future prospects.

Stabilization of Interstellar CSi Species by Donor Base Ligands: L-CSi-L; L = cAAC, NHC, and PMe.

The donor ligand bonded singlet (L)SiC containing a bent SiC unit in the middle has been studied by theoretical quantum mechanical calculations (NBO, QTAIM, EDA-NOCV analyses) [L = cAAC, NHC, MeP]. EDA-NOCV analysis suggests that this SiC is possible to stabilize by a pair of donor base ligands. The bond dissociation energy of the SiC fragment is endothermic (85-45 kcal/mol) with a sufficiently high intrinsic interaction energy (Δ = -89 to -48 kcal/mol).

Fluorescent organo-antimony compounds as precursors for syntheses of redox-active trimeric and dimeric alkali metal antimonides: an insight into electron transfer reduction processes.

(Tip)SbCl (1, Tip = 2,4,6-triisopropylphenyl) has been utilized as a precursor for the synthesis of the distibane (Tip)Sb (4) one-electron reduction using KC. The two-electron reduction of 1 and 4 afforded the novel trinuclear antimonide cluster [K((Tip)Sb)(THF)] (6). Changing the reducing agent from KC to a different alkali metal resulted in the solid-state isolation of corresponding stable dimeric alkali metal antimonides with the general formula [M((Tip)Sb)(THF)(tol)] (M = Li (14), Na (15), Cs (16)).

Estimations of Fe-N Intrinsic Interaction Energies of Iron-Sulfur/Nitrogen-Carbon Sites: A Deeper Bonding Insight by EDA-NOCV Analysis of a Model Complex of the Nitrogenase Cofactor.

The MoFeSC unit of the nitrogenase cofactor (FeMoco) attracts chemists and biochemists due to its unusual ability to bind aerial dinitrogen (N) at ambient condition and catalytically convert it into ammonia (NH). The mode of N binding and its reaction pathways are yet not clear. An important conclusion has been made based on the very recent synthesis and isolation of model Fe(I/0)-complexes with sulfur-donor ligands under the cleavage of one Fe-S bond followed by binding of N at the Fe(0) center.

EDA-NOCV Calculation for Efficient N Binding to the Reduced NiS Complex: Estimation of Ni-N Intrinsic Interaction Energies.

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 study model complexes in the laboratory. An electrochemically reduced form of a previously isolated sulfur-bridged NiS complex is inferred to bind N at multiple Ni centers, and this bonded N undergoes reductive protonation to produce hydrazine (NH) as the product in the presence of a proton donor.

Energy Decomposition Analysis Coupled with Natural Orbitals for Chemical Valence and Nucleus-Independent Chemical Shift Analysis of Bonding, Stability, and Aromaticity of Functionalized Fulvenes: A Bonding Insight.

The Donor base ligand-stabilized cyclopentadienyl-carbene compounds L-CH (L = HC, aAAC; (COMe)C, Py; aNHC, NHC, PPh; SNHC; aAAC = acyclic alkyl(amino) carbene, aNHC = acyclic N-hetero cyclic carbene, NHC = cyclic N-hetero cyclic carbene, SNHC = saturated N-hetero cyclic carbene, Py = pyridine) (, , ) have been theoretically investigated by energy decomposition analysis coupled with natural orbitals for chemical valence calculation. Among all these compounds, aNHC=CH () and PhP=CH () had been reported five decades ago. The bonding analysis of compounds with the general formula L=CH () [L = (HC, aAAC, (COMe)C, Py] showed that they possess one electron-sharing σ bond and electron-sharing π bond between L and CH neutral fragments in their triplet states as expected.

Stabilization of group 14 elements E = C, Si, Ge by hetero-bileptic ligands cAAC, MCO with push-pull mechanism.

The stability and bonding of a series of hetero-diatomic molecules with general formula (cAAC)EM(CO) , 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.

Bonding and stability of donor ligand-supported heavier analogues of cyanogen halides (L')PSi(X)(L).

Fluoro- and chloro-phosphasilynes [X-Si[triple bond, length as m-dash]P (X = F, Cl)] belong to a class of illusive chemical species which are expected to have Si[triple bond, length as m-dash]P multiple bonds. Theoretical investigations of the bonding and stability of the corresponding Lewis base-stabilized species (L')PSi(X)(L) [L' = cAAC (cyclic alkyl(amino) carbene); L = cAAC, NHC (N-heterocyclic carbene), PMe, aAAC (acyclic alkyl(amino) carbene); X = Cl, F] have been studied using the energy decomposition analysis-natural orbitals for chemical valence (EDA-NOCV) method. The variation of the ligands (L) on the Si-atom leads to different bonding scenarios depending on their σ-donation and π-back acceptance properties.

Revisiting the Bonding Scenario of Two Donor Ligand Stabilized C Species.

Quantum chemical calculations using density functional methods were performed for complexes of type LC with L = NHC (), SNHC () (S = saturated), cAAC (), and diamidocarbene (DAC) (). The equilibrium structures of - possess almost linear C cores. A high thermochemical stability of the complexes with respect to dissociation, LC → C + 2L, is indicated by the large bond dissociation energy following the order > > > .

Highly fluorescent aryl-cyclopentadienyl ligands and their tetra-nuclear mixed metallic potassium-dysprosium clusters.

Two alkyl substituted triaryl-cyclopentadienyl ligands [4,4'-(4-phenylcyclopenta-1,3-diene-1,2-diyl)bis(methylbenzene) (1) and 4,4',4''-(cyclopenta-1,3-diene-1,2,4-triyl)tris(methylbenzene) (2)] have been synthesized cross-aldol condensation followed by Zn-dust mediated cyclization and acid catalyzed dehydration reactions. The fluorescence properties of 1 and 2 have been studied in solution and solid state. The ligands exhibited aggregation-induced emission enhancement (AIEE) in THF/water solution.