The two-coordinate cationic Ni(I) bis-N-heterocyclic carbene complex [Ni(6-Mes)2]Br (1) [6-Mes =1,3-bis(2,4,6-trimethylphenyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene] has been structurally characterized and displays a highly linear geometry with C-Ni-C angle of 179.27(13)°. Density functional theory calculations revealed that the five occupied metal-based orbitals are split in an approximate 2:1:2 pattern. Significant magnetic anisotropy results from this orbital degeneracy, leading to...

Transition metal-alkane complexes-termed σ-complexes because the alkane donates electron density to metal from a σ-symmetry carbon-hydrogen (C-H) orbital-are key intermediates in catalytic C-H activation processes, yet these complexes remain tantalizingly elusive characterization solid state by single-crystal x-ray diffraction techniques. Here, we report an approach synthesis and of transition simple gas-solid reaction produce σ-complex directly. This strategy enables structural...

The mechanism of the zirconium-catalyzed condensation carboxylic acids and amines for direct formation amides was studied using kinetics, NMR spectroscopy, DFT calculations. reaction is found to be first order with respect catalyst has a positive rate dependence on amine concentration. A negative acid concentration observed along S-shaped kinetic profiles under certain conditions, which consistent reversible off-cycle species. Kinetic experiments progress analysis protocols demonstrate that...

Abstract Comproportionation of [Ni(cod) 2 ] (cod=cyclooctadiene) and [Ni(PPh 3 ) X (X=Br, Cl) in the presence six‐, seven‐ eight‐membered ring N ‐aryl‐substituted heterocyclic carbenes (NHCs) provides a route to series isostructural three‐coordinate Ni I complexes [Ni(NHC)(PPh )X] Cl; NHC=6‐Mes 1 , 6‐Anis 6‐AnisMes 7‐ o ‐Tol 4 8‐Mes 5 8‐ 6 O‐8‐ 7 ). Continuous wave (CW) pulsed EPR measurements on reveal that spin Hamiltonian parameters are particularly sensitive changes NHC size,...

Detailed experimental and computational studies are reported on the mechanism of coupling alkynes with 3-arylpyrazoles at [Rh(MeCN)3Cp*][PF6]2 [RuCl2(p-cymene)]2 catalysts. Density functional theory (DFT) calculations indicate a involving sequential N–H C–H bond activation, HOAc/alkyne exchange, migratory insertion, C–N reductive coupling. For rhodium, activation is two-step process comprising κ2–κ1 displacement acetate to give an agostic intermediate which then undergoes cleavage via proton...

Multiple metal-bound oligomers in the dehydropolymerisation of H₃B·NH₃ have been observed experimentally and mechanism oligomerisation probed computationally.

An analysis of the geometries and electronic structures a series [LnM(CX3)] species (where X = H, F) is presented, on basis density functional theory (DFT) natural bonding orbital (NBO) approach. Computed show that LnM–CF3 bonds can be up to 0.1 Å shorter than equivalent LnM–CH3 bonds, although extent this shortening varies considerably depending LnM fragment. Evidence for CF3 having higher trans influence CH3 seen, but most apparent in systems where bond itself shorter. NBO calculations...

Semihydrogenation of internal alkynes catalyzed by the air-stable imidazolyl amino [Mo

Azobenzene hydrogenation is catalyzed under moderate conditions by a cuboidal Mo3(μ3-S)(μ-S)3 diamino complex via cluster catalysis mechanism. Dihydrogen activation the molecular [Mo3(μ3-S)(μ-S)3Cl3(dmen)3]+ cation takes place at μ-S bridging atoms without direct participation of metals in clear contrast with classical concepts. The reaction occurs formation 1,2-diphenylhydrazine as an intermediate similar appearance and disappearance rate constants. On basis DFT calculations, mechanism...

The molybdenum(IV) cluster hydrides of formula [Mo3S4H3(diphosphine)3]+ with diphosphine = 1,2-(bis)dimethylphosphinoethane (dmpe) or (+)-1,2-bis-(2R,5R)-2,5-(dimethylphospholan-1-yl)ethane ((R,R)-Me-BPE) have been isolated in moderate to high yields by reacting their halide precursors borohydride. Complex [Mo3S4H3((R,R)-Me-BPE)3]+ as well its tungsten analogue are obtained optically pure forms. Reaction the incomplete cuboidal [M3S4H3((R,R)-Me-BPE)3]+ (M Mo, W) complex acids CH2Cl2 solution...

A series of new homoditopic ligands (14–17) containing two bis(pyrazol-1-yl)methane moieties connected to either flexible (1,6-bis(bis(pyrazol-1-yl)methyl)hexane, L6C (14); 1,7-bis(bis(pyrazol-1-yl)methyl)heptane, L7C (15)) or rigid scaffolds (4,5-bis(bis(pyrazol-1-yl)methyl)-9,9-dimethylxanthene, LXan (16); 4,6-bis(bis(pyrazol-1-yl)methyl)dibenzofuran, LDib (17)) were synthesized. bimetallic rhodium(I) complexes [Rh2(CO)4(LX)][BArF4]2 (X = Xan (8), Dib (9), Fc...

Abstract The reaction of the hydride cluster [W 3 S 4 H (dmpe) ] + ( 1 , dmpe=1,2‐bis(dimethylphosphanyl)ethane) with acids (HCl, CF COOH, HBF ) in CH 2 Cl solution under pseudo‐first‐order conditions excess acid occurs three kinetically distinguishable steps that can be interpreted as corresponding to successive formal substitution processes coordinated hydrides by anion COOH) or solvent (HBF ). Whereas rate law for third step changes nature acid, first two kinetic always show a...

A combined experimental and computational study on the fluxional processes involving M-H B-H positions in sigma amine-borane complexes [M(PR3)2(H)2(η(2)-H3B·NMe3)][BAr(F)4] (M = Rh, Ir; R Cy for experiment; Me, computation; Ar(F) 3,5-(CF3)2C6H3) is reported. The studied are: bridging/terminal exchange; reaction with exogenous D2 leading to exchange at M-H; intramolecular M-H/B-H exchange. Experimentally it was found that most accessible slightly favoured Rh; D2/M-H occurs qualitatively...

Abstract Detailed experimental and computational studies have been carried out on the oxidative coupling of alkenes C 2 H 3 Y (Y=CO Me ( a ), Ph b C(O)Me c )) with 3‐aryl‐5‐R‐pyrazoles (R=Me 1 CF using [Rh(MeCN) Cp*][PF 6 ] /Cu(OAc) ⋅ O catalyst system. In reaction methyl acrylate , up to five products aa – ) were formed, including trans monovinyl product, either complexed within novel Cu I dimer or as free species divinyl ); both underwent cyclisation by an aza‐Michael give fused...

The host-guest binding properties of a water-soluble resorcinarene-based cavitand are examined using density functional theory methodology. Experimentally, the has been observed to self-assemble in aqueous solution into both 1:1 and 2:1 host/guest complexes with hydrophobic guests such as n-alkanes. For n-decane, equilibrium was between complexes, while formed shorter n-alkanes longer ones. These findings used assess standard quantum chemical It is first shown that rather advanced...

The [Mo3S4Cl3(dhmpe)3]Cl ([1]Cl) cluster has been prepared from [Mo3S7Cl6]2- and the water-soluble 1,2-bis(bis(hydroxymethyl)-phosphino)ethane (dhmpe, L) ligand. crystal structure determined by X-ray diffraction methods shows incomplete cuboidal typical of M3Q4 clusters (M = Mo, W; Q S, Se), with a capping sulfide ligand to three metal centers other sulfides acting as bridges between two Mo atoms. octahedral coordination around each center is completed chlorine phosphorus atoms one L...

The hydrolytic degradation of squaramides and squaramic acids, the product partial hydrolysis squaramides, has been evaluated by UV spectroscopy at 37 °C in pH range 3–10. Under these conditions, compounds are kinetically stable over long time periods (>100 days). At >10, squaramate anions shows first-order dependence on both OH–. same temperature [OH–], usually displays biphasic spectral changes (A → B C kinetic model) with formation squaramates as detectable reaction intermediates....

Efficient protocols for the semihydrogenation of internal alkynes and terminal alkynols are reported using new [Mo 3 S 4 Cl (ImNH 2 ) ] + complex as catalyst.

The reaction of Pd(dba)2 (dba = dibenzylideneacetone) with [W3Se4(H2O)9]4+ in 2 M HCl gives the cuboidal cluster [W3(PdCl)Se4(H2O)9]3+, which undergoes edge-to-edge condensation and crystallizes from Hpts solutions as edge-linked double-cubane [{W3PdSe4(H2O)9}2](pts)8·18H2O (pts− p-toluenesulfonate). substitution Cl− by different ligands, including phenylsulfinate PhSO2−, was explored. complex crystallized a 2:1 adduct cucurbit[6]uril (C36H36N24O12),...

The synthesis of two new ligands constituted a tris(2-aminoethyl)amine moiety linked to the 2,6 positions pyridine spacer through methylene groups in which hanging arm is further functionalized with 2-pycolyl (L1) or 3-pycolyl (L2) group presented. protonation L1 and L2 formation Cu2+ complexes have been studied using potentiometric, NMR, X-ray, kinetic experiments. results provide information about relevance molecular movements chemistry this kind so-called scorpiand ligand. comparison...

Density functional theory calculations have been employed to model the double C-Cl bond activation of CH(2)Cl(2) at [CoCl(PR(3))(3)] give [CoCl(3)(CH(2)PR(3))(PR(3))(2)]. Calculations incorporating dichloromethane solution (PCM approach) on a [CoCl(PMe(3))(3)] system showed two cleavage steps involve different mechanisms. The first step occurs triplet surface and proceeds via Cl abstraction with barrier 19.1 kcal mol(-1). Radical recombination would then singlet...

A new tetraaza-pyridinophane macrocycle (L1) N-alkylated with two isopropyl and one methyl groups symmetrically disposed has been prepared its behavior compared those of the unsubstituted pyridinophane (L3) related compound three (L2). The protonation studies show that, first, a proton binds to central methylated amine group L1, while, second leads reorganization protons that are at this stage attached lateral isopropylated amines. X-ray structure [HL1]+ agrees UV–vis NMR as well results DFT...

UV irradiation of Cp′Mn(CO)3 (Cp′ = η5-C5H4Me) in the presence free N-heterocyclic carbenes IEt2Me2, IiPr2Me2, IMes, and IPr affords NHC dicarbonyl complexes Cp′Mn(CO)2(NHC) (1–4). Time-resolved infrared spectroscopy alkane solution reveals that 1–4 photodissociate CO to generate Cp′Mn(CO)(NHC) (1-CO, 2-CO, 3-CO, 4-CO), which exhibit solvent-independent second-order rate constants (kCO) for reaction with CO. These observations are consistent 1-CO 4-CO being stabilized by intramolecular...

For many years it has been known that the nine water molecules in [M(3)Q(4)(H(2)O)(9)](4+) cuboidal clusters (M = Mo, W; Q S, Se) can be replaced by entering ligands, such as chloride or thiocyanate, and kinetic studies carried out mainly on substitution of first molecule at each metal centre reveal reaction three centres occurs with statistical kinetics; is, a single exponential rate constant corresponding to third is observed instead expected three-exponential trace. Such simplification...

Treatment of the triangular [Mo3S4Cl3(dbbpy)3]Cl cluster ([1]Cl) with CuCl produces a novel tetrametallic cuboidal [Mo3(CuCl)S4Cl3(dbbpy)3][CuCl2] ([2][CuCl2]), whose crystal structure was determined by X-ray diffraction (dbbpy = 4,4'-di-tert-butyl-2,2'-bipyridine). This species, which contains two distinct types Cu(I), is first example diimine-functionalized heterometallic M3M'S4 cluster. Kinetics studies on both formation cubane from parent trinuclear and its dissociation after treatment...