SPh functionalized bridging-vinyliminium diiron and diruthenium complexes

The SPh functionalized vinyliminium complexes [Fe₂{μ-η¹:η³-C_γ(R′)C_β(SPh)C_αN(Me)(R)}(μ-CO)(CO)(Cp)₂][SO₃CF₃] [R = Xyl, R′ = Me, 2a; R = Me, R′ = Me, 2b; R = 4-C₆H₄OMe, R′ = Me, 2c; R = Xyl, R′ = CH₂OH, 2d; R = Me, R′ = CH₂OH, 2e; Xyl = 2,6-Me₂C₆H₃] are generated in high yields by treatment of the corresponding vinyliminium complexes [Fe₂{μ-η¹:η³-C_γ(R′)C_β(H)C_αN(Me)(R)}(μ-CO)(CO)(Cp)₂][SO₃CF₃] (1a-e) with NaH in the presence of PhSSPh. Likewise, the diruthenium complex [Ru₂{μ-η¹:η³-C_γ(Me)C_β(SPh)C_αN(Me)(Xyl)}(μ-CO)(CO)(Cp)₂][SO₃CF₃] (2f) was obtained from the corresponding vinyliminium complex [Ru₂{μ-η¹:η³-C_γ(Me)C_β(H)C_αN(Me)(Xyl)}(μ-CO)(CO)(Cp)₂] (1f). The synthesis of 2c is accompanied by the formation, in comparable amounts, of the aminocarbyne complex [Fe₂{μ-CN(Me)(4-C₆H₄OMe)}(SPh)(μ-CO)(CO)(Cp)₂] (3).The molecular structures of 2d, 2e and 3 have been determined by X-ray diffraction studies.     

Ethynylferrocene insertion into Fe-C bond in bridging aminocarbyne diiron complexes: New triiron vinyliminium complexes

The μ-aminocarbyne complexes [Fe₂{μ-CN(Me)(R)}(μ-CO)(CO)(NCMe)(Cp)₂][SO₃CF₃] (R = Me, 1a; Xyl, 1b; Xyl = 2,6-Me₂C₆H₃) react with ethynylferrocene to give the corresponding bridging vinyliminium complexes [Fe₂{μ-η¹:η³-CN(Me)(R)CHC(Fc)}(μ-CO)(CO)(Cp)₂][SO₃CF₃] (R = Me, 2a; R = Xyl, 2b). Insertion of the ethynylferrocene in the metal-carbyne bond is regiospecific, and leads to the formation of only one isomer.Complexes 2a and 2b undergo hydride addition (by NaBH₄) affording the enaminoalkylidene complex [Fe₂{μ-η¹:η³-C(H)(N(Me)₂)CHC(Fc)}(μ-CO)(CO)(Cp)₂] (3a) and the bis-alkylidene [Fe₂{μ-η¹:η²-C(N(Me)(Xyl))CH₂C(Fc)}(μ-CO)(CO)(Cp)₂] (3b), respectively. Upon treatment with NaH, compounds 2a and 2b undergo fragmentation, affording the 1-metalla-2-aminocyclopenta-1,3-dien-5-one complexes [Fe(CO)(Cp){C(N(Me)(R))}CHC(Fc)C(O)}] (R = Me, 4a; R = Xyl, 4b).The molecular structures of 2b, 3b and 4b have been determined by X-ray diffraction studies.     

Addition of alkynes at bridging vinyliminium ligands in diiron complexes: Unprecedented diene formation by enyne-like metathesis

The zwitterionic bridging vinyliminium complex [Fe₂{μ-η¹:η³-C(Tol)C(CS₂)CN(Me)₂}(μ-CO)(CO)(Cp)₂] (5a) undergoes the addition of two equivalents of MeO₂C-CC-CO₂Me affording the bridging bis-alkylidene complex [Fe₂{μ-η¹:η³-C(Me)C{C(CO₂Me)C(CO₂Me)CSC(CO₂Me)C(CO₂Me)S}CNMe₂}(μ-CO)(CO)(Cp)₂] (6). One alkyne unit inserts into a C-CS₂ bond of the bridging ligand, with consequent rearrangement that leads to the formation of a diene. The reaction shows analogies with the enyne metathesis. The second alkyne is incorporated into the bridging frame via cycloaddition at the thiocarboxylate function, affording a 1,3-dithiolene. The complexes [Fe₂{μ-η¹:η³-C(R′)C(CS₂)CN(Me)(R)}(μ-CO)(CO)(Cp)₂] (R = Xyl, R′ = Tol, 5b; R = p-C₆H₄OMe, R′ = Me, 5c; Xyl = 2,6-Me₂C₆H₃), treated with MeO₂C-CC-CO₂Me and then with HBF₄, undergo the cycloaddition of the alkyne with the dithiocarboxylate group and protonation of the dithiocarboxylate carbon, affording the complexes [Fe₂{μ-η¹:η³-C(R′)C{C(H)SC(CO₂Me)C(CO₂Me)S}CN(Me)(R)}(μ-CO)(CO)(Cp)₂][BF₄] (R = Xyl, R′ = Tol, 7a; R = p-C₆H₄OMe, R′ = Me, 7b), respectively.The X-ray molecular structure of 6 has been determined.     

Syntheses, crystal structures of a series of copper(II) complexes and their catalytic activities in the green oxidative coupling of 2,6-dimethylphenol

Three mixed-ligand Cu^II complexes bearing iminodiacetato (ida) and N-heterocyclic ligands, namely, [Cu₂(ida)₂(bbbm)(H₂O)₂] · H₂O (1), [Cu₂(ida)₂(btx)(H₂O)₂] · 2H₂O (2) and [Cu₂(ida)₂(pbbm)(H₂O)₂] · H₂O · 3CH₃OH (3) (bbbm = 1,1^′-(1,4-butanediyl)bis-1H-benzimidazole, btx = 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene, pbbm = 1,1^′-(1,3-propanediyl)bis-1H-benzimidazole), in addition to three fcz-based Cu^II complexes, namely, {[Cu(fcz)₂(H₂O)₂] · 2NO₃}_n (4), {[Cu(fcz)₂(H₂O)] · SO₄ · DMF · 2CH₃OH · 2H₂O}_n (5) and {[Cu(fcz)₂Cl₂] · 2CH₃OH}_n (6) (fcz = 1-(2,4-difluorophenyl)-1,1-bis[(1H-1,2,4-triazol-l-yl) methyl]ethanol) have been prepared according to appropriate synthetic strategies with the aim of exploiting new and potent catalysts. Single crystal X-ray diffraction shows that 1 and 2 possess similar binuclear structures, 3 features a 2D pleated network, and 4 exhibits a 1D polymeric double-chain structure. Complexes 1-6 are tested as catalysts in the green catalysis process of the oxidative coupling of 2,6-dimethylphenol (DMP). Under the optimized reaction conditions, these complexes are catalytically active by showing high conversion of DMP and high selectivity of PPE. The preliminary study of the catalytic-structural correlations suggests that the coordination environment of the copper center have important influences on their catalytic activities.     

Peroxide-mediated oxidative coupling of primary alcohols and disulfides: Synthesis of 2-substituted benzothiazoles

A peroxide-mediated protocol for the synthesis of 2-substituted benzothiazoles was developed, starting from bis(o-aminophenyl) disulfides and primary alcohols. Eleven differently 2-substituted benzothiazoles were prepared in moderate to excellent yields using di-tert-butyl peroxide (DTBP) as an oxidant.     

Syntheses, structures and reactivities of diindenyl-coordinated diiron bridging carbene complexes

Compound [Fe₂(μ-CO)₂(CO)₂(η⁵-C₉H₇)₂] (1) reacts with aryllithium reagents, ArLi (Ar = C₆H₅, p-CH₃C₆H₄, p-CF₃C₆H₄) followed by alkylation with Et₃OBF₄ to give the diindenyl-coordinated diiron bridging alkoxycarbene complexes [Fe₂{μ-C(OC₂H₅)Ar}(μ-CO)(CO)₂(η⁵-C₉H₇)₂] (2, Ar = C₆H₅; 3, Ar = p-CH₃C₆H₄, 4, Ar = p-CF₃C₆H₄). Complex 4 reacts with HBF₄ · Et₂O at low temperature to yield cationic bridging carbyne complex [Fe₂(μ-CC₆H₄CF₃-p)(μ-CO)(CO)₂(η⁵-C₉H₇)₂]BF₄ (5). Cationic 5 reacts with NaBH₄ in THF at low temperature to afford diiron bridging arylcarbene complex [Fe₂{μ-C(H)C₆H₄CF₃-p}(μ-CO)(CO)₂(η⁵-C₉H₇)₂] (6). The reaction of 5 with NaSC₆H₄CH₃-p under the similar conditions gave the bridging arylthiocarbene complex [Fe₂{μ-C(C₆H₄CF₃-p)SC₆H₄CH₃-p}(μ-CO)(CO)₂(η⁵-C₉H₇)₂] (7). Complex 5 can also react with carbonylmetal anionic compounds Na[M(CO)₅(CN)] (M = Cr, Mo, W) to produce the diiron bridging aryl(penta-carbonylcyanometal)carbene complexes [Fe₂{μ-C(C₆H₄CF₃-p)NCM(CO)₅}(μ-CO)(CO)₂(η⁵-C₉H₇)₂] (8, M = Cr; 9, M = Mo; 10, M = W). The structures of complexes 4, 6, 7, and 10 have been established by X-ray diffraction studies.     

Electroactive polyimide with oligoaniline in the main chain via oxidative coupling polymerization

By oxidative coupling polymerization of the imidic macromonomer of oligoaniline and p-phenylenediamine we have prepared an electroactive polyimide, exhibiting exciting molecular structure, electrochemical properties and excellent thermal stability. The polymerization characteristics and structure of the electroactive polyimide were systematically studied by Fourier-transform infrared (FTIR) spectra and X-ray powder diffraction (XRD). Electrochemical activity of the polyimide was tested in 1.0 M H₂SO₄ aqueous solution and it shows two redox peaks, which is the same as that of polyaniline. Moreover, the thermal properties of the polyimide were evaluated by thermogravimetric analysis (TGA). Its electrical conductivity is about 8.87 × 10⁻⁶ S cm⁻¹ at room temperature upon preliminarily protonic-doped experiment.     

Substituted (pyridinyl)benzoazole palladium complexes: Synthesis and application as Heck coupling catalysts

The synthesis of 2-(4-tert-butylpyridin-2-yl)-benzooxazole (L3), 2-(4-tert-butyl-pyridin-2-yl)-benzothiazole (L4) and 6-tert-Butyl-2-(4-tert-butyl-pyridin-2-yl)-benzothiazole (L5) by intramolecular cyclization under basic conditions is described. Reactions of 2-pyridin-2-yl-1H-benzoimidazole (L1), 2-pyridin-2-yl-benzothiazole (L2) and L3–L5 with either [Pd(NCMe)₂Cl₂] or [Pd(COD)MeCl] afforded the corresponding mononuclear palladium complexes [Pd(L1)MeCl] (1), [Pd(L2)MeCl] (2), [Pd(L3)Cl₂] (3), [Pd(L3)MeCl] (4), [Pd(L4)Cl₂] (5), [Pd(L4)MeCl] (6) and [Pd(L4)MeCl] (7) as confirmed by mass spectrometry and elemental analyses. The palladium complexes are efficient Heck coupling catalysts for the reaction of iodobenzene with butylacrylate under mild conditions. Benzothiazole and benzooxazole containing complexes show faster induction periods compared to the benzoimidazole analogues.     

A comparative study on the nature and strength of O–O, S–S, and Se–Se bond

A computational study on dichalcogenide molecules (R₂X₂; X = O, S, Se; R = H, CH₃, NH₂) has been carried out employing B3LYP and MP2 levels using 6-31+G*, 6-311+G*, 6-311++G**, and PVDZ basis sets. The relative energies have been evaluated at G2MP2 also. The rotational barriers and bond dissociation energies indicate that S–S bond is stronger than Se–Se and O–O bond. NBO analysis at MP2/6-31+G* suggest the presence of partial π character between X–X bond that decreases in the order S–S > Se–Se > O–O. Fuki functions for nucleophilic and electrophilic attack fail to distinguish the reactivity of S and Se. The proton affinities of the O₂H₂, S₂H₂, Se₂H₂ decrease in the order Se > S > O.     

Monophosphine‐substituted diiron azadithiolate complexes: New syntheses,characterization and electrochemical properties

Investigating the synthesis and properties of diiron azadithiolate complexes is one of the key topics for mimicking the active site of [FeFe]‐hydrogenases, which might be very useful for the design of new efficient catalysts for hydrogen production and the development of a future hydrogen economy. A series of new phosphine‐substituted diiron azadithiolate complexes as models for the active site of [FeFe]‐hydrogenases are described. A novel and efficient way was firstly established for the preparation of phosphine‐substituted diiron azadithiolate complexes. The reaction of Fe₂(μ‐SH)₂(CO)₆ and phosphine ligands L affords the intermediate Fe₂(μ‐SH)₂(CO)₅L ( A ). The intermediate reacts in situ with a premixed solution of paraformaldehyde and ammonium carbonate to produce the target phosphine‐substituted diiron azadithiolate complexes Fe₂[(μ‐SCH₂)₂NH](CO)₅L ( 1a – 1f ) (L = P(C₆H₄–4‐CH₃)₃, P(C₆H₄–3‐CH₃)₃, P(C₆H₄–4‐F)₃, P(C₆H₄–3‐F)₃, P(2‐C₄H₃O)₃, PPh₂(OCH₂CH₃)). Furthermore, reactions of the intermediate A with I‐4‐C₆H₄N(CH₂Cl)₂ in the presence of Et₃N give the phosphine‐substituted diiron azadithiolate complexes Fe₂[(μ‐SCH₂)₂NC₆H₄–4‐I](CO)₅L ( 2a – 2e ) (L = P(C₆H₄–4‐CH₃)₃, P(C₆H₄–3‐CH₃)₃, P(C₆H₄–4‐F)₃, P(C₆H₄–3‐F)₃, P(2‐C₄H₃O)₃). All the complexes were fully characterized using elemental analysis, IR and NMR spectroscopies and, particularly for 1a , 1c – 1e , 2a and 2c , single‐crystal X‐ray diffraction analysis. In addition, complexes 1a – 1f and 2a – 2e were found to be catalysts for H₂ production under electrochemical conditions. Density functional theory calculations were performed for the reactions of Fe₂(μ‐SH)₂(CO)₆ + P(C₆H₄–4‐CH₃)₃.     

Synthesis and characterization of electroactive copolymer with phenyl-capped aniline tetramer in the main chain by oxidative coupling polymerization

A novel electroactive alternating copolymer, with fixed conjugated length of oligoaniline (phenyl-capped aniline tetramer) in the main chain, was successfully synthesized via oxidative coupling polymerization. The structure of the copolymer was systematically studied by Fourier-transform infrared (FTIR) spectra, NMR, elemental analysis (EA), UV-vis spectra and X-ray powder diffraction (XRD). And its electrochemical behavior was studied by cyclic voltammetry (CV) measurement. It was found that the obtained copolymer bearing phenyl-capped aniline tetramer segments had a reversible electrochemical property in the cyclic voltammetry, and the copolymer was oxidized to its emeraldine oxidation state and then to the pernigraniline oxidation state, which was same as that of polyaniline. Moreover, the thermal properties of the copolymer were evaluated by thermogravimetric analysis (TGA). The electrical conductivity of the obtained copolymer was about 1.43 × 10⁻⁷ S cm⁻¹ at room temperature.     

Synthesis of γ-halogenated ketones via the Ce(IV)-mediated oxidative coupling of cyclobutanols and inorganic halides

A straightforward method for the synthesis of γ-halo-substituted ketones formed via the CAN-initiated oxidative addition of halides to 1-substituted cyclobutanols has been developed. This method has short reaction times, and provides access to a range of bromo and iodo γ-substituted ketones in good to excellent yields.     

Synthesis of heterobimetallic Ru-Mn complexes and the coupling reactions of epoxides with carbon dioxide catalyzed by these complexes

The heterobimetallic complexes [(eta5-C5H5)Ru(CO)(mu-dppm)Mn(CO)4] and [(eta5-C5Me5)Ru(mu-dppm)(mu-CO)2Mn(CO)3] (dppm = bis-diphenylphosphinomethane) have been prepared by reacting the hydridic complexes [(eta5-C5H5)Ru(dppm)H] and [(eta5-C5Me5)Ru(dppm)H], respectively, with the protonic [HMn(CO)5] complex. The bimetallic complexes can also be synthesized through metathetical reactions between [(eta5-C5R5)Ru(dppm)Cl] (R = H or Me) and Li+[Mn(CO)5]-. Although the complexes fail to catalyze the hydrogenation of CO2 to formic acid, they catalyze the coupling reactions of epoxides with carbon dioxide to yield cyclic carbonates. Two possible reaction pathways for the coupling reactions have been proposed. Both routes begin with heterolytic cleavage of the RuMn bond and coordination of an epoxide molecule to the Lewis acidic ruthenium center. In Route I, the Lewis basic manganese center activates the CO2 by forming the metallocarboxylate anion which then ring-opens the epoxide; subsequent ring-closure gives the cyclic carbonate. In Route II, the nucleophilic manganese center ring-opens the ruthenium-attached epoxide to afford an alkoxide intermediate; CO2 insertion into the RuO bond followed by ring-closure yields the product. Density functional calculations at the B3LYP level of theory were carried out to understand the structural and energetic aspects of the two possible reaction pathways. The results of the calculations indicate that Route II is favored over Route I.     

TBAI/TBHP mediated oxidative cross coupling of ketones with phenols and carboxylic acids: Direct access to benzofurans

TBAI/TBHP mediated oxidative cross coupling of phenols and carboxylic acids with ketones has been reported under metal-free, base free, solvent free conditions enabling environmentally benign synthesis of aryloxyketones, acyloxy ketones and benzofurans. Phenoxyketones and acyloxylcarbonyl compounds were synthesized in good to high yields, where as benzofurans were synthesized in moderate yields. This method is operationally simple, works under mild conditions, using commercially available as well as inexpensive TBAI and an oxidant TBHP.     

Cationic methyl complexes of rhodium(III): synthesis, structure, and some reactions

Cationic methyl complex of rhodium(III), trans-[Rh(Acac)(PPh₃)₂(CH₃)(CH₃CN)][BPh₄] (1) is prepared by interaction of trans-[Rh(Acac)(PPh₃)₂(CH₃)I] with AgBPh₄ in acetonitrile. Cationic methyl complexes of rhodium(III), cis-[Rh(Acac)(PPh₃)₂ (CH₃)(CH₃CN)][BPh₄] (2) and cis-[Rh(BA)(PPh₃)₂(CH₃)(CH₃CN)][BPh₄] (3) (Acac, BA are acetylacetonate and benzoylacetonate, respectively), are obtained by CH₃I oxidative addition to rhodium(I) complexes [Rh(Acac)(PPh₃)₂] and [Rh(BA)(PPh₃)₂] in acetonitrile in the presence of NaBPh₄. Complexes 2 and 3 react readily with NH₃ at room temperature to form cis-[Rh(Acac)(PPh₃)₂(CH₃)(NH₃)][BPh₄] (4) and cis-[Rh(BA)(PPh₃)₂(CH₃)(NH₃)][BPh₄] (5), respectively. Complexes 1-5 were characterized by elemental analysis, ¹H and ³¹P{¹H} NMR spectra. Complexes 1, 2, 3 and 4 were characterized by X-ray diffraction analysis. Complexes 2 and 3 in solutions (CH₂Cl₂, CHCl₃) are presented as mixtures of cis-(PPh₃)₂ isomers involved into a fluxional process. Complex 2 on heating in acetonitrile is converted into trans-isomer 1. In parallel with that isomerization, reductive elimination of methyl group with formation of [CH₃PPh₃][BPh₄] takes place. Replacement of CH₃CN in complexes 1 and 2 by anion I⁻ yields in both cases the neutral complex trans-[Rh(Acac)(PPh₃)₂(CH₃)I]. Strong trans influence of CH₃ ligand manifests itself in the elongation (in solid) and labilization (in solution) of rhodium-acetonitrile nitrogen bond.     

Palladium acetate complexes bearing chelating N-heterocyclic carbene (NHC) ligands: Synthesis and catalytic oxidative homocoupling of terminal alkynes

The imidazolium salts 1,1′-dibenzyl-3,3′-propylenediimidazolium dichloride and 1,1′-bis(1-naphthalenemethyl)-3,3′-propylenediimidazolium dichloride have been synthesized and transformed into the corresponding bis(NHC) ligands 1,1′-dibenzyl-3,3′-propylenediimidazol-2-ylidene (L₁) and 1,1′-bis(1-naphthalenemethyl)-3,3′-propylenediimidazol-2-ylidene (L₂) that have been employed to stabilize the Pd^II complexes PdCl₂(κ²-C,C-L₁) (2a) and PdCl₂(κ²-C,C-L₂) (2b). Both latter complexes together with their known homologous counterparts PdCl₂(κ²-C,C-L₃) (1a) (L₃ = 1,1′-dibenzyl-3,3′-ethylenediimidazol-2-ylidene) and PdCl₂(κ²-C,C-L₄) (1b) (L₄ = 1,1′-bis(1-naphthalenemethyl)-3,3′-ethylenediimidazol-2-ylidene) have been straightforwardly converted into the corresponding palladium acetate compounds Pd(κ¹-O-OAc)₂(κ²-C,C-L₃) (3a) (OAc = acetate), Pd(κ¹-O-OAc)₂(κ²-C,C-L₄) (3b), Pd(κ¹-O-OAc)₂(κ²-C,C-L₁) (4a), and Pd(κ¹-O-OAc)₂(κ²-C,C-L₂) (4b). In addition, the phosphanyl-NHC-modified palladium acetate complex Pd(κ¹-O-OAc)₂ (κ²-P,C-L₅) (6) (L₅ = 1-((2-diphenylphosphanyl)methylphenyl)-3-methyl-imidazol-2-ylidene) has been synthesized from corresponding palladium iodide complex PdI₂(κ²-P,C-L₅) (5). The reaction of the former complex with p-toluenesulfonic acid (p-TsOH) gave the corresponding bis-tosylate complex Pd(OTs)₂(κ²-P,C-L₅) (7). All new complexes have been characterized by multinuclear NMR spectroscopy and elemental analyses. In addition the solid-state structures of 1b·DMF, 2b·2DMF, 3a, 3b·DMF, 4a, 4b, and 6·CHCl₃·2H₂O have been determined by single crystal X-ray structure analyses. The palladium acetate complexes 3a/b, 4a/b, and 6 have been employed to catalyze the oxidative homocoupling reaction of terminal alkynes in acetonitrile chemoselectively yielding the corresponding 1,4-di-substituted 1,3-diyne in the presence of p-benzoquinone (BQ). The highest catalytic activity in the presence of BQ has been obtained with 6, while within the series of palladium-bis(NHC) complexes, 4b, featured with a n-propylene-bridge and the bulky N-1-naphthalenemethyl substituents, revealed as the most active compound. Hence, this latter precursor has been employed for analogous coupling reaction carried out in the presence of air pressure instead of BQ, yielding lower substrate conversion when compared to reaction performed in the presence of BQ. The important role of the ancillary ligand acetate in the course of the catalytic coupling reaction has been proved by variable-temperature NMR studies carried out with 6 and 7′ under catalytic reaction conditions.     

Piperazine‐ and DABCO‐bridged dinuclear N‐heterocyclic carbene palladium complexes: synthesis,structure and application to Hiyama coupling reaction

Four dinuclear N ‐heterocyclic carbene (NHC) palladium complexes were prepared by reaction of imidazolinium salts, PdCl₂ and bridging ligands (piperazine and DABCO) in one pot or by direct cleavage of the chloro‐bridged dimeric compounds [Pd(μ ‐Cl)(Cl)(NHC)]₂ with bridging ligands. All of the complexes were fully characterized using ¹H NMR, ¹³C NMR, high‐resolution mass and infrared spectroscopies, elemental analysis and single‐crystal X‐ray diffraction. The catalytic activities of the obtained palladium catalysts towards Hiyama coupling of aryl chlorides with phenyltrimethoxysilane were investigated and the results showed that the dinuclear palladium complexes were considerably active for the coupling reaction. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis and characterization of some new aromatic diamine monomers from oxidative coupling of anilines and substituted aniline with 4-amino-N,N-dimethyl aniline

New aromatic diamine monomers prepared from condensation reactions of aniline, p-chloroaniline, p-nitro aniline, p-chloro-m-nitro aniline with 4-amino-N,N-dimethylaniline (2:1) (aniline:reagent) in the presence of potassium dichromate in acidic media yielded new monomers of a highly colored violet and reddish-violet. Mechanism of the reaction of aniline with 4-amino-N,N-dimethylaniline in the presence of potassium dichromate as an oxidant is expected to proceed through nucleophilic substitution reaction, and the mechanism proceeds facilitated a nucleophilic attack of the substituted aniline ring on the –NH₂ group of the reagent; through partial protonation of their –NH₂ group, forming in diamine dye and their identification was confirmed by IR, ¹H NMR, and CHN analyses.     

Elongated dihydrogen versus compressed dihydride complexes: the temperature dependence of the H-D spin-spin coupling constant as a criterion to distinguish between them

To be able to propose experimental tests to distinguish elongated dihydrogen transition-metal complexes from compressed dihydride transition-metal complexes, a thorough density functional study of the electronic structure in combination with quantum nuclear dynamics calculations have been performed for complexes [Cp*Ru(H2PCH2PCH2(H2)]+ and [CpRe(CO)2H2]. The results of this study suggest that elongated dihydrogen complexes and compressed dihydride complexes have different properties and that it should be possible to distinguish between them experimentally. In particular, different behavior is predicted with respect to 1) the sign of the isotope geometric effect on the H-H distance at 0 K, 2) the temperature dependence of the H-H distance, and 3) the temperature dependence of the H-D spin-spin coupling constant in 1H NMR spectroscopy.