Η2 Coordination Research Articles

Iodine-induced stepwise reactivity of coordinated white phosphorus: A mechanistic overview

The main role of the Ruthenium metal in the stepwise demolition of the P4 ligand upon the reaction with I2 is to enhance the basicity of the phosphorus atoms. The first step of reaction goes through the η2 coordination of the P4 moiety. The bounded phosphorus atoms are able to interact with the di-iodine molecule allowing the formation of tri-iodide anions. The latter, once released, may exert their nucleophilic action toward the transient unsaturated coordinated phosphorus centre. Such a vacancy is partially fulfilled by the metal through the formation of a partial Ru=P double bond. A detailed analysis of the evolution of the electronic structure at the various intermediates allows to discriminate in between the possible different initial adducts and to predict the most stable product. In contrast with the unassisted reaction, no concerted mechanism has been pointed out but the process evolves through a stepwise cleavage of the three PP bonds involving the coordinated phosphorus up to the final PI3 ligand formation and a cyclo-P3I3 moiety.

Synthesis, Structure, Reactivity and Catalytic Implications of a Cationic, Acetylide-Bridged Trigold-JohnPhos Species.

The cationic complex [(JohnPhos-Au)3 (acetylide)][SbF6 ] (JohnPhos=(2-biphenyl)di-tert-butylphosphine, L1) has been characterised structurally and features an acetylide-trigold(I)-JohnPhos system; the trinuclear-acetylide unit, coordinated to the monodentate bulk phosphines, adopts an unprecedented μ,η1 ,η2 ,η1 coordination mode with an additional interaction between distal phenyl rings and gold centres. Other cationic σ,π-[(gold(I)L1)2 ] complexes have also been isolated. The reaction of trimethylsilylacetylene with various alcohols (iPrOH, nBuOH, n-HexOH) catalysed by cationic [AuI L1][SbF6 ] complexes in CH2 Cl2 at 50 °C led to the formation of acetaldehyde acetals with a high degree of chemo- and regioselectivity. The reaction mechanism was studied, and several organic and inorganic intermediates have been characterised. A comparative study with the analogous cationic [CuI L1][PF6 ] complex revealed different behaviour; the copper metal is lost from the coordination sphere leading to the formation of cationic vinylphosphonium and copper nanoparticles. Additionally, a new catalytic approach for the formation of this high-value cationic vinylphosphonium has been established.

Computational Study of an Iron(II) Polypyridine Electrocatalyst for CO2 Reduction: Key Roles for Intramolecular Interactions in CO2 Binding and Proton Transfer

A solar-driven conversion of CO2 into fuels by artificial photosynthesis would not only mitigate the greenhouse effect but also provide an alternative to obtain fuels in a renewable fashion. To this end, the new iron polypyridine catalyst [Fe(bpyNHEtPY2Me)L2]2+ (L = H2O, CH3CN) was recently developed for the electrochemical reduction of CO2 to CO. In this study, we performed density functional theory (DFT) electronic structure calculations to shed light on a possible pathway for CO2 reduction and the origin of the selectivity between CO2 reduction versus the hydrogen evolution reaction. The metal center remains Lewis acidic throughout the reduction process due to ligand loss and mainly ligand-based reduction stabilized by antiferromagnetic coupling to a high-spin Fe(II) center. This results in a high barrier for hydride formation but a facile addition and activation of CO2 via an η2 coordination and stabilizing hydrogen bonding by the amine group. The second unoccupied equatorial coordination site opens up the possibility for an intramolecular protonation with a coordinated water ligand. This facilitates protonation because not only CO2 but also the proton source H2O is activated and properly aligned for a proton transfer due to the Fe-OH2 bond; consequently, both protonation steps are facile. The moderate ligand field allows a rapid ligand exchange for a second intramolecular protonation step and facilitates an exergonic CO release. The lower selectivity of the related [Fe(bpyOHPY2Me)L2]2+ complex can be related to its more acidic second coordination sphere, which enables an intramolecular proton transfer that is kinetically competitive with CO2 addition.

Palladium-Catalyzed [5 + 2] Heteroannulation of Phenethylamides with 1,3-Dienes to Dopaminergic 3-Benzazepines.

Phenethyltriflamides react with 1,3-dienes upon treatment with a catalytic amount of Pd(OAc)2 and Cu(OAc)2/O2 as oxidant to afford chemo-, regio- and diastereoselectively 2,3,4,5-tetrahydro-1H-benzo[d]azepines (3-benzazepine derivatives) in good to excellent yields. A DFT study of the [5 + 2] heteroannulation suggests a mechanistic pathway starting with formation of the six-membered palladacycle cis-PdX2L2 via a CMD process followed by η2 coordination and insertion of the 1,3-diene unit in a diastereoselective manner.

Rare‐Earth Metal Alkyl Complexes with 3‐Arylamido‐Functionalized Indolyl Ligands: Synthesis, Characterization and Reactivity†

Summary of main observation and conclusionA series of dinuclear rare‐earth metal alkyl complexes {[μ‐η2:η1:η1‐3‐(LNCH)(CH2SiMe3)Ind]RE(CH2SiMe3)(THF)}2 (L1 = 2‐tBuC6H4, RE = Y, Gd, Dy, Er, Yb; L2 = 2,4,6‐Me3C6H2, RE = Dy, Er; Ind = indolyl) and {[μ‐η2:η1:η1‐3‐(LNCH2)Ind]RE(CH2SiMe3)(THF)}2 (L1, RE = Y, Dy, Er, Yb; L2, RE = Er, Yb) bearing 3‐arylamido functionalized indolyl ligands having diverse bonding modes with metal ions were synthesized either by the insertion reaction of the imino group to the RE—C bond or by the alkane elimination reaction. In the preparation of above complexes, rare‐earth metal alkyl complexes [μ‐η5:η1:η1‐3‐(L2NCH)(CH2SiMe3)Ind]Gd(CH2SiMe3)(THF)}2 with a μ‐η5:η1:η1 coordination mode to the gadolinium ion and {[μ‐η3:η1:η1‐3‐(L2NCH2)Ind]Dy(CH2SiMe3)(THF)}2 with a μ‐η3:η1:η1 coordination mode to the dysprosium ion were unexpectedly isolated. The reactions of 3‐(L2N=CH)Ind with Er(CH2SiMe3)3(THF)2 at room temperature, generated a tetranuclear imino‐indolyl erbium intermediate {[μ‐η1:η1‐3‐(L2N=CH)Ind]Er(CH2SiMe3)2(THF)}4, which can transform into the amido functionalized indolyl erbium complex in hot toluene. Moreover, the reactivities of the newly synthesized ytterbium complex with N‐heterocyclic compounds were investigated, affording the corresponding products of the mixed pyridyl‐indolyl, imidazolyl‐indolyl, and ortho‐metalated complexes. The yttrium complexes showed a high regioselectivity and steroselectivity for the isoprene polymerization with 1,4‐trans selectivity up to 91.7% and 1,4‐cis selectivity up to 96.1% in the presence of cocatalysts, respectively.

Synthesis, Structure, and Reactivity of Dicationic Bimetallic Tetrabenzyldihafnium Complexes Bearing a Chelating (2-Hydroxyethyl)amido Ligand

We prepared the bimetallic hafnium complex 1 by reaction of Hf(CH2Ph)4 with the alcohol-imine proligand L via deprotonation and subsequent benzyl migration from the hafnium atom to the imine moiety of L. The complex 1 was obtained as a diastereomeric mixture of 1a (SR, heterochiral) and 1b (RR and SS, homochiral); the SR isomer 1a was readily isolated by simply washing with toluene. Treatment of 1a with [Ph3C][B(C6F5)4] in C6H5Cl afforded the dicationic complex 2a, which was characterized by spectroscopic data and an X-ray diffraction study, revealing the η6 coordination of the phenyl group bound to the chelating ligand to the cationic hafnium center. Complex 2a showed catalytic activity for 1-hexene oligomerization at 100 °C in combination with 2 equiv of [Ph3C][B(C6F5)4], while 4,4′-dimethoxydiphenylacetylene reacted with 2a to quantitatively afford alkene 3 at room temperature after hydrolysis. The addition of PMe2Ph and pyridine to 2a dissociated the η6-arene coordination of the ligand to give the corresponding adducts 5a and 6a, whose structures were fully characterized by X-ray diffraction analysis.

Insights on uranium uptake mechanisms by ion exchange resins with chelating functionalities: Chelation vs. anion exchange

Abstract X-ray absorption fine structure analysis has been successfully used to determine the coordination environment and therefore uptake mechanism towards the uranyl cation for a selection of commercially available ion exchange resins in non-saline and saline conditions ([Cl−] = 22.7 g L−1, 0.64 M) similar to those found in sea water. The resins tested were Purolite S985, S910 and S957, Dowex M4195, Ps-EDA, Ps-DETA and Ps-PEHA, which contain polyamine, amidoxime, mixed sulfonic/phosphonic acid, bispicolylamine, ethylenediamine, diethylenetriamine and pentaethylenehexamine functional groups, respectively. Purolite S910 and S957 were both found to extract the uranyl cation through a chelation mechanism. The uranium coordination environment on uranyl loaded Purolite S910 was found to be either tetra- or hexa-coordinate in the equatorial plane, with a 2:1 ratio of amidoxime:uranium in the fit suggesting either monodentate or η2 coordination by two amidoxime groups. The uranium environment for uranyl loaded Purolite S957 was found to be tetra-coordinate in the equatorial plane, with both sulfonic and phosphonic acid groups being involved in sorption. The presence of chloride in the loading solution had no effect on the uranyl coordination environment observed on any of the resins. In contrast, Dowex M4195, Purolite S985, Ps-EDA, Ps-DETA and Ps-PEHA exhibited an anion exchange mechanism for uranyl uptake as the corresponding extended X-ray absorption fine structure (EXAFS) data best fit a [UO2(SO4)3]4− structure.

Thermally Stable Half-Sandwich Benzhydryl Ln(II) (Ln = Sm, Yb) Complexes Supported by Sterically Demanding Carbazolyl and Fluorenyl Ligands

A series of new isolable and thermally stable half-sandwich Ln(II) benzhydryl complexes coordinated by the sterically demanding ligands tert-butylcarbazol-9-yl [tBu4Carb]Ln[(p-tBu-C6H4)2CH](L) (Ln = Sm, L = DME (4); Ln = Yb, L = DME (5); Ln = Yb, L = TMEDA (6)) and 2,7-di-tert-butyl-fluoren-9-trimethylsilylyl [2,7-tBu2-9-Me3Si-C13H6]Yb[(p-tBu-C6H4)2CH](DME) (7) were synthesized by the alkane elimination reaction of [(p-tBu-C6H4)2CH]2Ln(Ln) (Ln = Sm, Yb) with tBu4CarbH and 2,7-tBu2-9-Me3Si-C13H7. X-ray analysis revealed that in 4, 5, and 7 the benzhydryl ligand is coordinated to the metal ion in an η3 coordination mode, while in 6 it is η1-bound. The type of coordination of the benzhydryl ligands in diamagnetic 5–7 is retained in their C6D6 solutions. Complexes 4–7 demonstrated unprecedented thermal stability and do not undergo decomposition after heating their solutions in C6D6 or toluene at 100 °C for 72 h. The reactions of [tBu4Carb]Ln[(p-tBu-C6H4)2CH](DME) (Ln = Sm (4), Ln = Yb (5)) with an excess of DME led to the formation of the symmetrical bis(carbazolyl) complex products [tBu4Carb]2Ln(DME)4 (Ln = Sm (8), Yb (9)) isolated in the form of separated ion pairs.

Lithium Complexes with Bridging and Terminal NHC Ligands: The Decisive Influence of an Anionic Tether

Deprotonation of the fluorenyl‐tethered imidazolinium salt [9‐(C13H9)C2H4N(CH)C2H4N(2,4,6‐Me3C6H2)][BF4] gave a spirocyclic compound that reacted with a synergic mixture of LiPh/LiN(SiMe3)2 or LinBu/LiN(SiMe3)2 to give a dilithium complex incorporating a bridging N(SiMe3)2 ligand. In contrast, deprotonation of the imidazolium salt [9‐(C13H9)C2H4N(CH)C2H2N(Me)][Br] instead yielded the free NHC, which reacted with nBuLi to form a dimeric, NHC‐bridged dilithium complex. Addition of LiN(SiMe3)2 led to coordination and the formation of a dilithium complex with a bridging N(SiMe3)2 ligand, which was characterised in the solid state as a 1D coordination polymer. The reaction of 1,3‐bis(2,6‐diisopropylphenyl)‐4,5‐dihydroimidazol‐2‐ylidene (SIPr) with lithium indenide and lithium fluorenide gave soluble species with terminal binding of the NHC to the lithium cation and η5 coordination of indenyl or fluorenyl. A symmetrical bridging mode for an NHC donor was therefore observed only if a tethered fluorenyl anion was present with no additional amide ligand.

Ruthenocenyl phosphinated chalcones and their Pt(II) and Pd(II) complexes: Usual bidentate [PO] and unusual tridentate [PCO] coordination

New ruthenocenyl phosphinated chalcones β-(2′-diphenylphosphinophenyl)-acrylruthenocene CpRu(C5H4)C(O)–CHCHC6H4PPh2 (2) and β-(2′-ditolylphosphinophenyl)-acrylruthenocene CpRu(C5H4)C(O)–CHCHC6H4P(tolyl)2 (3) and their Pt(II) and Pd(II) complexes [MCl(κ3-PCO)] (4)–(6) were synthesized as the predominant product, where chalcones coordinate in a tridentate fashion to the metal center and present an unusual η1 coordination at the double bond by activation of C–H bond. During the isolation of Pt(II) (6) complex, a new unstable platinum phosphino-alkene complex (7) [PtCl2(κ2-PO)]was also isolated as a minor product. The X-ray crystal structure of (7) confirms that ligand (2) acts as bidentate ligand and coordinates through phosphorus and η2 double bond ligation to Pt(II) metal. Solution NMR and X-ray crystal structure of chalcone confirm the presence of (E)-stereochemistry at the double bond and s-cis conformation of the enone portion and complexes show square planar geometry around the metal center. Complex (7) decomposes to complex (6) and the oxidized product of ruthenocenyl phosphinated chalcone. Quasi-reversible electrochemistry was found for the ruthenocenyl center in these compounds in acetonitrile solvent. Compared to the ligands, the corresponding metal complexes are easier to oxidize at ruthenocenyl center. From quantum chemical calculations of model systems of (6) and (7) where a platinum atom is replaced by a palladium atom, it was observed that the bonding strength in a η1 coordinated complex is stronger than in a η2 coordinated double bond complex, because of the better chelating effect of the ligand in former complex.

A Series of Lanthanide-Based Metal-Organic Frameworks Derived from Furan-2,5-dicarboxylate and Glutarate: Structure-Corroborated Density Functional Theory Study, Magnetocaloric Effect, Slow Relaxation of Magnetization, and Luminescent Properties.

Herein, through a dual-ligand strategy, we report eight isorecticular lanthanide(III) furan-2,5-dicarboxylic acid metal-organic frameworks (Ln-MOFs) with the general formula {[Ln(2,5-FDA)0.5(Glu)(H2O)2]· xH2O} n [Ln = Sm (1), Eu (2), Gd (3), Tb (4), Dy (5), Ho (6), Er (7), and Yb (8); 2,5-FDA2- = furan-2,5-dicarboxylate and Glu2- = glutarate; x = 0.5 for 1, 2, and 4 and x = 0 for 3 and 5-8], synthesized under solvothermal conditions by using an N, N'-dimethylformamide/H2O mixed solvent system. Crystallographic data reveal that all eight Ln-MOFs 1-8 crystallize in the orthorhombic Pnma space group. All of the MOFs are isostructural as well as isomorphous with distorted monocapped square-antiprismatic geometry around the Ln1 metal center. In Ln-MOFs 1-8, the 2,5-FDA2- and Glu2- ligands exhibit μ2-κ4,η1:η1:η1:η1 and μ3-κ5,η2:η1:η1:η1 coordination modes, respectively. Topologically, assembled Ln-MOFs 1-8 consist of the 2D cem topological type. The designed Ln-MOFs 1-8 are further explored for structure-corroborated density functional theory study. Meanwhile, room temperature photoluminescence properties of Ln-MOFs 2 and 4 and magnetic properties of Ln-MOFs 3 and 5 have been explored in detail. A highly intense, ligand-sensitized, Ln3+ f-f photoluminescence emission is exhibited by Ln-MOFs 2 [Eu3+ (red emission)] and 4 [Tb3+ (green emission)]. Magnetic studies suggest weak antiferro- and ferromagnetic interactions between adjacent GdIII ions in Ln-MOF 3, thereby displaying a large magnetocaloric effect. The magnetic data measured at T = 2 K and Δ H = 30 kOe depict that the -Δ Sm value per unit mass reaches 32.1 J kg-1 K-1, which is larger than most of the GdIII-based complexes reported. The alternating-current susceptibility measurements on Ln-MOF 5 revealed that out-of-phase signals are frequency- and temperature-dependent under both 0 and 2 kOe direct-current fields, thereby suggesting a typical slow magnetic relaxation behavior with two relaxation processes. This is further supported by the Cole-Cole plots at 2.4-6 K.

Synthesis, structure and magnetism of a novel CuII4TiIV5 heterometallic cluster

A nonanuclear CuII4TiIV5 heterometallic cluster, [Ti5Cu4O6(ba)16] (1, Hba = benzoic acid) was synthesized in one-pot reaction under the solvothermal condition. The metallic skeleton 1 contains a Ti5 core constructed from two vertex-shared Ti3 triangles and four separated Cu atoms outside which are connected together by μ3-O2− ions. Total 16 ba− ligands adopt μ2-η1: η1 coordination mode to protect the overall heterometallic core. Due to the unique d-d transitions of CuII ion, the reflectance spectrum of 1 displays broad and strong absorption towards visible light extending to the near-infrared region. Moreover, 1 shows almost purely paramagnetic behavior with the presence of weak antiferromagnetic interactions at low temperatures.

Viability of half sandwich complexes of borole with group 14 (II) ions: Structure, stability and reactivity

Density functional theory (DFT) calculations have been carried out to investigate the viability of the formation of half sandwich complexes of borole dianion with group 14 dications. All these sandwich complexes have been found to be thermodynamically stable. The reactivity of these half sandwich complexes has also been studied. They have high proton affinity as well as hydride ion affinity indicating their ambiphilic character. The kinetics of their formation has also been studied which indicates that there is very low barrier for formation of most of the complexes. Topological analyses within the realm of quantum theory of atoms in molecules (QTAIM) and electron localization function (ELF) suggest that the borole dianion prefers η5 coordination modes. Energy decomposition analysis was performed to obtain a better insight of the interaction between the key fragments which indicates that all these molecules have significant covalency which increases down the group.

Synthesis, characterization and structure of thiolate-bridged diruthenium and iron-ruthenium complexes with isocyanide ligands

Interaction of the mixed-valent iron-ruthenium heterodinuclear precursor [Cp*Fe(μ-η2:η4-bdt)RuCp*][PF6] (1[PF6], Cp* = η5-C5Me5, bdt = benzene-1,2-dithiolate) with isocyanides resulted in coordination activation to give several thiolate-bridged iron-ruthenium complexes bearing isocyanide in excellent yields. Crystallographic analysis clearly reveals the isocyanide ligand is terminally end-on bonded to the iron center and the bdt ligand adopts a rare μ-η2:η6 coordination mode. Interestingly, when the diruthenium hydride-bridged complex is treated with excess isocyanides, the reductive elimination reaction takes place to afford free Cp*H, meanwhile, six isocyanide molecules supplement the remaining coordination spheres of the diruthenium centers.

μ-Carbonyl-bis(carbonyl{η5-[tricarbonyl(η6-2-methylindenyl)chromium(0)]rhodium(III)})(Rh—Rh)

The structure of the title complex, [Cr2Rh2(C10H9)2(CO)9], was solved by single-crystal X-ray diffraction analysis in the P21/c space group. The crystal shows two units of the tetrametallic complex in the asymmetric unit. The most remarkable features of this new compound are the asymmetric bonding of the RhIII atom to the indenyl ligand, which can be formulated in terms of an η2;η3 coordination rather than η5, and the Rh—Rh distances of 2.6756 (6) and 2.6737 (6) Å that are characteristic of an intermetallic interaction supported by a bridging carbonyl ligand. The infrared spectroscopic signature informs of its clear bridging feature characterized by a significantly elongated C=O bond length compared to those in the two Rh-bound `terminal' carbonyl ligands.

DFT investigation of homotrinuclear and heterotrinuclear [M3(Phz)2], [MM′2(Phz)2], [M3(CO)2(Phz)2], [MM′2(CO)2(Phz)2] sandwich complexes (M = Ti, Cr, Fe and Ni; M′ = V and Mn, Phz = C12H8N2): predicted models and electronic structures

The results described in this work report a DFT/BP86 (using the TZ2P basis) study concerning the molecular and electronic structures of homotrinuclear and heterotrinuclear substituted and unsubstituted complexes. It is about the interaction between a trimetallic M3 moiety flanked between two phenazine (Phz) ligand which is a 14-π electron donor ligand. Each of the six-membered rings of each phenazine tends to establish M-L bonding with various hapticies from η2 to η6 according to the electron need and the nature of the metal. The most stable [Ti3(Phz)2] and [Cr3(Phz)2] complexes have a comparable closed-shell electronic configuration of 18-/18-/18-MVE with the same η6,η6,η6 coordination mode. However, the [Cr3(Phz)2] and [Ni3(Phz)2] complexes correspond to 17-/18-/17 and 14-/14-/14-MVE electronic configurations, respectively. The unsubstituted heterotrinuclear [Cr(V)2(Phz)2] and [Cr(Mn)2(Phz)2] complexes are the most stable in the models wherein the highest electronegative atoms are adjacent, contrary to the [Ti(V)2(Phz)2] species which are favored in the case where the identical Ti atoms are separated by the vanadium one. All unsubstituted complexes display M-M bonding, conversely to the carbonyl-substituted complexes which prefer the M-CO bonding rather than the M-M ones. The triple, double, and single M-M bonding present in the proposed models are identified by the bond distances, Wiberg index, and MO plots according to the valence electron count of the M3 moiety.

Unexpected Multiple Coordination Modes in Silyl-Bridged Bis(phosphinine) Complexes

The bis(phosphinine) [bis{3-methyl-6-(trimethylsilyl)phosphinine-2-yl}dimethylsilane] (1) was synthesized and its coordination chemistry explored. Molybdenum and chromium carbonyl complexes were crystallographically characterized featuring 1 bound η6 through one phosphinine [Mo(CO)3(η6-1)] (2Mo), η6 through both phosphinines to two metal centers [{M(CO)3}2(μ-η6:η6-1)] (3M2, M = Cr, Mo), and chelating with η1 coordination through both phosphines [M(CO)4(κ:η1:η1-1)] (4M, M = Cr, Mo). However, only 3Mo2 could be isolated analytically pure. Heating species 3Mo2 in the presence of [Pd(COD)Cl2] removed one CO ligand and generated [{Mo(CO)2}(μ-κ:η1η6-η6-1){Mo(CO)3}] (5), which is the first crystallized example of a bis(phosphinine) featuring chelating η1 and η6 coordination, as well as a metal center bound to two phosphinines with different binding modes. In order to enforce a chelating bis-η1 binding mode, the Ru complex [Ru(Cp*)(Cl)(κ:η1:η1-1)] (6) was prepared, demonstrating that judicious choice of metal fra...

Coordination Compounds of Palladium(II) and 4‐Amino‐1,2,4‐triazole

Mononuclear coordination compounds of the type [Pd(NH2trz)4]2+ with the counterions chloride, nitrate, trifluoromethanesulfonate, and methanesulfonate were synthesized and their structures identified with single‐crystal X‐ray diffraction. In case of the synthesis with methanesulfonate as the counterion the dominant product was of the generic formula [Pd2(NH2trz)3](CH3SO3)4, and the complex [Pd(NH2trz)4](CH3SO3)2 only emerged as a byproduct. While the structure of the byproduct could be analyzed by single‐crystal X‐ray diffraction, suitable crystals of the main product [Pd2(NH2trz)3](CH3SO3)4 could not be obtained. However, stoichiometry implies a polynuclear nature with NH2trz present in the rare μ3‐η1:η1:η1 coordination type, i.e. with NH2trz molecules coordinating to three palladium atoms. Accordingly, identification of solids by single‐crystal analysis alone can be misleading in particular with NH2trz as a ligand due to its versatile coordination behavior. Finally, analysis by differential scanning calorimetry (DSC) revealed that the complexes were thermally stable (the onset of decomposition well above 100 °C), with [Pd2(NH2trz)3](CH3SO3)4 being the most stable compound (onset of decomposition at 204 °C).

A computational investigation of stereochemical preferences in the oxidative addition of allylic substrates on Mo(CO)3L: L = (S,S)-(2-pyridinecarboxamide)-(2-phenylcarboxamide)-1,2-cyclohexane

The coordination and oxidative addition of (E)-3-phenyl-2-propenyl methyl carbonate (1) and (S/R)-1-phenyl-2-propenyl methyl carbonates (2) on Mo(CO)3L have been investigated computationally. In addition to the anticipated η2 coordination mode of these allylic carbonates prior to their oxidative addition on molybdenum, hydrogen bonding between the leaving group of the substrates and the coordinated amide group of L as well as between the amide groups of L, plays an important role in the stereochemical control of this reaction.

NMR study of the Ni complexes based on 1-alkyl-1,2-diphospholes

The structures of the nickel complexes based on 1-alkyl-1,2-diphospholes in a solution were determined using 1D/2D homo- and heterocorrelation NMR experiments. The η2 coordination mode at the P–P bond is observed in the complexes.