Applications of a monomeric orthopalladate complex containing mixed phosphorus-nitrogen donors in the Heck reaction

The [Pd{C₆H₂(CH₂CH₂NH₂)-(OMe)₂,3,4}Br(PPh₃)] monomeric orthopalladate complex of homoveratrylamine and triphenylphosphine was synthesized and its application in Heck coupling reactions was investigated. This complex had been demonstrated to be more active than the corresponding dimeric catalyst for Heck reactions of aryl iodides, bromides and even chlorides and also arenesulfonyl chlorides. The cross-coupled products were produced in excellent yields using catalytic amounts of [Pd{C₆H₂(CH₂CH₂NH₂)-(OMe)₂,3,4}Br(PPh₃)] as a thermally stable and oxygen insensitive complex in NMP at 130 °C.     

Microwave-assisted Stille and Hiyama cross-coupling reactions catalyzed by ortho-palladated complexes of homoveratrylamine

The activity of dimeric [Pd{C₆H₂(CH₂CH₂NH₂)-(OMe)₂-3,4}(μ-Br)]₂ and monomeric [Pd{C₆H₂(CH₂CH₂NH₂)-(OMe)₂-3,4}Br(PPh₃)] complexes as efficient, air, and moisture tolerant catalysts was investigated in Stille and Hiyama cross-coupling reactions of various aryl halides. Substituted biaryls were produced in excellent yields in short reaction times using these complexes. The monomeric complex had been demonstrated to be more active than the corresponding dimeric catalyst for the cross-coupling of some of aryl bromides and unreactive aryl chlorides. The combination of homogenous metal catalyst, microwave irradiation, and microwave-active polar solvents gave high yields of products in short reaction times.     

Accelerated Heck reaction using ortho‐palladated complex with controlled microwave heating

Palladium‐catalyzed Heck couplings utilizing [Pd{C₆H₂(CH₂CH₂NH₂)‐(OMe)₂,3,4} (µ‐Br)]₂ palladacycle catalyst and microwave irradiation lead to formation of different coupling products. This complex is an active and efficient catalyst for the Heck reaction of aryl iodides, bromides and even less reactive chlorides. The cross‐coupled products were produced in excellent yields. The reaction time was reduced from hours to minutes and full conversion was achieved under microwave irradiation. Copyright © 2009 John Wiley & Sons, Ltd.     

Application of dimeric cyclopalladated complex of tribenzylamine as an efficient catalyst in the Heck cross-coupling reaction

The activity of [Pd{C₆H₄(CH₂N(CH₂Ph)₂)} (μ-Br)]₂ complex was investigated in the Heck-Mizoroki C-C cross-coupling reaction. This complex is an active and efficient catalyst for the Heck reaction of aryl iodides, bromides and even chlorides and also arenesulfonyl chlorides. The cross-coupled products were produced in excellent yields in short reaction time using a catalytic amount of [Pd{C₆H₄(CH₂N(CH₂Ph)₂) (μ-Br)]₂ complex in NMP at 130 °C.     

Accelerated Heck reaction using ortho‐palladated complex in a nonaqueous ionic liquid with controlled microwave heating

The activity of {Pd[C₆H₂(CH₂CH₂NH₂)‐(OMe)₂,3,4] (µ‐Br)}₂ complex was investigated in the Heck–Mizoroki C C cross‐coupling reaction under conventional heating and microwave irradiation conditions in molten salt tetrabutylammonium bromide as the solvent and promoter at 130 °C. This complex in these conditions is an active and efficient catalyst for the Heck reaction of aryl iodides, bromides and even chlorides, and also arenesulfonyl chlorides. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis of substituted biaryls via Suzuki,Stille and Hiyama cross‐coupling and homo‐coupling reactions by CN‐dimeric and monomeric ortho‐palladated catalysts

The catalytic activity of dimeric [Pd{C₆H₂(CH₂CH₂NH₂)–(OMe)₂,2,3}(μ‐Br)]₂ and monomeric [Pd{C₆H₂(CH₂CH₂NH₂)–(OMe)₂,2,3}Br(PPh₃)] complexes as efficient, stable and air‐ and moisture‐tolerant catalysts was investigated in the Suzuki, Stille and Hiyama cross‐coupling and homo‐coupling reactions of various aryl halides. Substituted biaryls were produced in excellent yields in short reaction times using catalytic amounts of these complexes. The monomeric complex was demonstrated to be more active than the corresponding dimeric catalyst for the cross‐coupling reaction of unreactive aryl bromides and chlorides. The combination of homogeneous metal catalysts and microwave irradiation gave higher yields of products in shorter reaction times. Copyright © 2013 John Wiley & Sons, Ltd.     

Application of ortho‐palladated homoveratrylamine complex containing mixed phosphorus–nitrogen donors in the Suzuki reaction

The catalytic activity of [Pd{C₆H₂(CH₂CH₂NH₂)‐(OMe)₂,3,4}Br(PPh₃)] monomeric ortho‐palladated complex of homoveratrylamine and triphenylphosphine was investigated in the Suzuki cross‐coupling reaction of various aryl halides with aryl boronic acids. The substituted biaryls were produced in excellent yields using a catalytic amount of this complex in ethanol at 60°C. Copyright © 2012 John Wiley & Sons, Ltd.     

Palladium‐catalyzed cyanation reaction of aryl halides using K4[Fe(CN)6] as non‐toxic source of cyanide under microwave irradiation

An efficient method for preparation of aryl nitriles—using [Pd{C₆H₂(CH₂CH₂ NH₂)‐(OMe)₂,3,4} (µ‐Br)]₂ complex as an efficient catalyst and K₄[Fe(CN)₆] as a green cyanide source—from aryl bromides, aryl iodides and aryl chlorides under microwave irradiation has been reported. This complex has been demonstrated to be an active and efficient catalyst for this reaction. Using a catalytic amount of this synthesized palladium complex in DMF at 130 °C led to production of the cyanoarenes in excellent yields in short reaction times. Copyright © 2010 John Wiley & Sons, Ltd.     

Microwave-enhanced synthesis of aryl nitriles using dimeric orthopalladated complex of tribenzylamine and K4[Fe(CN)6]

The activity of palladacycle [Pd{C₆H₄(CH₂N(CH₂Ph)₂)} (μ-Br)]₂ complex was investigated in the synthesis of benzonitriles under both conventional and microwave irradiation conditions and their results were compared together. This complex is an efficient, stable, and non-sensitive to air and moisture catalyst for the cyanation reaction. The substituted benzonitriles were produced of various aryl halides in excellent yields and short reaction times using a catalytic amount of [Pd{C₆H₄(CH₂N(CH₂Ph)₂)} (μ-Br)]₂ complex and K₄[Fe(CN)₆] in DMF at 130 °C. In comparison to conventional heating conditions, the reactions under microwave irradiation gave higher yields in shorter reaction times.     

CN-Dimeric ortho-palladated complex catalyzed cyanation of aryl halides under microwave irradiation

The catalytic activity of dimeric [Pd{C₆H₂(CH₂CH₂NH₂)–(OMe)₂,2,3}(m-Br)]₂ complex was investigated in the synthesis of benzonitriles under microwave irradiation conditions. The substituted benzonitriles were produced from various aryl halides in excellent yields and short reaction times using a catalytic amount of this complex as efficient, stable and air- and moisture-tolerant catalyst, and K₄[Fe(CN)₆] as a green cyanide source in DMF at 130 °C.     

Palladium-Catalyzed Synthesis of Symmetrical Biaryls Under Microwave Irradiation and Conventional Heating

The activity of the [Pd{C₆H₄(CH₂N(CH₂Ph)₂)}(µ-Br)]₂ complex was investigated in the synthesis of symmetrical biaryls under both conventional and microwave irradiation conditions, and their results were compared. This complex is efficient, stable, and not sensitive to air or moisture and is a catalyst for the homo-coupling reaction of aryl iodides, bromides, and even chlorides. The products were produced in excellent yields in short reaction times using a catalytic amount of [Pd{C₆H₄(CH₂N(CH₂Ph)₂)(µ-Br)]₂ complex in N-methylpyrolidine (NMP) at 130 °C. In comparison to conventional heating conditions, the reactions under microwave irradiation gave better yields in shorter reaction times.     

Metallabis(phosphonate) als Chelatliganden. II. Synthese und Reaktivität ein- und zweikerniger Palladiumbis(phosphonat)-Komplexe mit OHO- und OBF2O-Brückenbindungen

Metallabisphosphonates as Chelating Ligands. II. Synthesis and Reactivity of Mono- and Binuclear Palladiumbisphosphonate Complexes Containing OHO and OBF₂O Bridges The complexes C₅H₅Pd[{P(OR)₂O}₂H] ( 1 : R = Me; 2 : R = Et) are formed either by reaction of C₅H₅Pd(2-MeC₃H₄) with dimethyl- and diethylphosphite or by reaction of [ClPd{P(OR)₂O}₂H]₂ ( 3 : R = Me; 4 : R = Et) with TlC₅H₅. With excess HP(O)(OMe)₂, the π-allyl complex (2-MeC₃H₄)Pd[{P(OMe)₂O}₂H] ( 5 ) is also formed (besides 1 ) from C₅H₅Pd(2-MeC₃H₄). The ¹H and ³¹P n.m.r. spectra indicate that in 1 – 5 the PdP₂O₂H chelate ring presumably contains a symmetrical OHO-hydrogen bond. The reaction of 3 with BF₃ etherate leads to the binuclear complex [ClPd{P(OMe)₂O}₂BF₂]₂ ( 6 ) which reacts with TlC₅H₅ to yield C₅H₅Pd[{P(OMe)₂O}₂BF₂] ( 7 ). From C₅H₅Pd[{P(OR)₂O}₂H] ( 1 , 2 ) and NH₃ the bisamminepalladium bisphosphonates(NH₃)₂Pd[P(OR)₂O]₂ ( 8 , 9 ) are formed which probably possess a trans-configuration. The reaction of 8 , 9 with CF₃COOH does not lead to a corresponding Pd[{P(OR)₂O}₂H] chelate complex but instead gives by elimination of NH₃ polymeric palladium bisphosphonates [Pd{P(OR)₂O}₂]_n ( 10 , 11 ). 1 reacts with thallium acetylacetonate to give C₅H₅Pd[P(OMe)₂O]₂Tl ( 12 ).     

Functionalized cyclopalladated compounds with bidentate Group 15 donor atom ligands: the crystal and molecular structures of [{Pd[5-(COH)C6H3C(H)NCy-C2,N](Cl)}2(μ-Ph2PRPPh2)] (R=CH2CH2, Fe(C5H4)2], [Pd{5-(COH)C6H3C(H)NCy-C2,N}(Ph2PCH2PPh2-P,P)][PF6] and [Pd{5-(COH)C6H3C(H)N(Cy)-C2,N}(Ph2PCH2CH2AsPh2-P,As)][PF6]

The chloro-bridged dinuclear compound [{Pd[5-(COH)C₆H₃C(H)N(Cy)-C2,N]}(μ-Cl)]₂ (1), reacts with tertiary diphosphines in 1:1 molar ratio to give [{Pd[5-(COH)C₆H₃C(H)NCy-C2,N](Cl)}₂(μ-Ph₂PRPPh₂)] (R: CH₂, 2; CH₂CH₂, 3; (CH₂)₄, 4; (CH₂)₆, 5; Fe(C₅H₄)₂, 6; trans-CHCH, 7; C≡C, 8). Treatment of 1 with Ph₂PCH₂CH₂AsPh₂ (arphos) gives the dinuclear complex [{Pd[5-(COH)C₆H₃C(H)N(Cy)-C2,N](Cl)}₂(μ-Ph₂PCH₂CH₂AsPh₂)] (9). The reaction of 1 with tertiary diphosphines or arphos in 1:2 molar ratio in the presence of NH₄PF₆ yields the mononuclear compounds [Pd{5-(COH)C₆H₃C(H)NCy-C2,N}(Ph₂PRPPh₂-P,P)][PF₆] (R: (CH₂)₄, 10; (CH₂)₆, 11; Fe(C₅H₄)₂, 12; 1,2-C₆H₄, 13; cis-CHCH, 14; NH, 15) and [Pd{5-(COH)C₆H₃C(H)N(Cy)-C2,N}(Ph₂PCH₂CH₂AsPh₂-P,As)][PF₆] (16). ¹H-, ³¹P-{¹H}- and ¹³C-{¹H}-NMR, IR and mass spectroscopic data are given. The crystal structures of compounds 3, 6, 9 and 16 have been determined by X-ray crystallography.     

The Synthesis,Characterisation, and Reactivity of Some Polydentate Phosphinoamine Ligands with Benzene‐1,3‐diyl and Pyridine‐2,6‐diyl Backbones

The polydentate phosphinoamines 1,3‐{(Ph₂P)₂N}₂C₆H₄ and 2,6‐{(Ph₂P)₂N}₂C₅H₃N have been prepared in a single step from the reaction of the amines 1,3‐(NH₂)₂C₆H₄ or 2,6‐(NH₂)₂C₅H₃N with Ph₂PCl in presence of Et₃N (1 : 4 : 4 molar ratio) in CH₂Cl₂. Reaction of 1,3‐{(Ph₂P)₂N}₂C₆H₄ or 2,6‐{(Ph₂P)₂N}₂C₅H₃N with elemental sulfur or selenium in CH₂Cl₂ affords the corresponding tetrasulfide or tetraselenide, respectively, in good yield. The complexes [1,3‐{Mo(CO)₄(Ph₂P)₂N}₂(C₆H₄)] and [2,6‐{Mo(CO)₄(Ph₂P)₂N}₂(C₅H₃N)] were prepared from the reaction of these phosphinoamines with [Mo(CO)₄(nbd)] (nbd=norbornadiene) in toluene, and the structure of the latter complex has been determined by single‐crystal X‐ray diffraction analysis.     

Synthesis and structure of mono- and di-nuclear complexes of ortho-palladated derived from phosphorus ylides

The phosphorus ylides Ph₃PCHC(O)C₆H₄R (R = 4-Me 1a, 4-Br 1b) react with PdCl₂ in equimolar ratios to give the C,C-orthopalladated [Pd{CHP(C₆H₄)Ph₂CO-C₆H₄-R)}(μ-Cl)]₂ (R = 4-Me 2a, 4-Br 2b) which react with NaClO₄/dppe, NaClO₄/dppm, py and PPh₃ to give the mononuclear derivatives [Pd{CH{P(C₆H₄)Ph₂}COC₆H₄-R}(dppe-P,P′)[(ClO₄) (R = 4-Me 3a, 4-Br 3b), [Pd{CH{P(C₆H₄)Ph₂}COC₆H₄-R}(dppm-P,P′)[(ClO₄ ( (R = 4-Me 4a, 4-Br 4b), [Pd{CH{P(C₆H₄)Ph₂}COC₆H₄-R}Cl(L)] (L = py, R = 4-Me 5a, 4-Br 5b, L = PPh₃, R = 4-Me 6a, 4-Br 6b). The C, C-metalated chelate are demonstrated by an X-ray diffraction study of 3a and 4a. Characterization of the obtained compounds was also performed by elemental analysis, IR, ¹H, ³¹P, and ¹³C NMR.     

Metallation of aliphatic carbon atoms: II,syntheses and characterization of the cyclopalladated complexes of N,N-dimethylneopentylamine

N,N-Dimethylneopentylamine reacts with Pd(MeCO₂)₂ to give a novel trinuclear cyclopalladated complex [Me₂NCH₂CMe₂CH₂Pd(μ-MeCO₂)₂Pd(μ-MeCO₂)₂PdCH₂CMe₂CH₂NMe₂]?-0.5C₆H₆ (I). The reaction of I with PPh₃ affords both trans-[Pd(MeCO₂)₂(PPh₃)₂] (II) and [Pd(CH₂CMe₂CH₂NMe₂)(MeCO₂)(PPh₃)] (III). The reaction of III with LiCl yields a mononuclear cyclopalladated complex, [Pd(CH₂CMe₂CH₂NMe₂)Cl(PPh₃)] (IV).     

A convenient entry into diruthenium chemistry

In boiling toluene, diphenylacetylene is readily displaced from the dimetallocycle [Ru₂(CO)(μ-CO) {μ-C(O)C₂Ph₂} (η-C₅H₅)₂] by a variety of reagents (P(OMe)₃, SO₂, R₂CN₂, Ph₂PCH₂) to produce [Ru₂(CO){P(OMe)₃}(μ-CO)₂ - (η-C₅H₅)₂] or [Ru₂(CO)₂(μ-CO)(μ-L)(η-C₅H₅)₂] (L  SO₂, CR₂, CH₂) in high yield.     

Ein μ2-Benzylidenkomplex des Chroms mit ungepaarten Elektronen

The benzylidene-bridged dichromium complex [CpCr]₂(μ-Br)₂(μ-CHC₆H₅) (4) has been obtained by thermolysis of [CpCr(CH₂C₆H₅)]₂(μ-Br)₂. ¹H NMR spectroscopy shows that 4 is antiferromagnetic and a barrier of 64.0 kJ mol⁻¹ slows down the rotation of the phenyl group.     

Large bite bisphosphite, 2,6-C5H3N{CH2OP(-OC10H6)(μ-S)(C10H6O-)}2: Synthesis, derivatization, transition metal chemistry and application towards hydrogenation of olefins

Large bite bisphosphite ligand, 2,6-C₅H₃N{CH₂OP(-OC₁₀H₆)(μ-S)(C₁₀H₆O-)}₂ (2), is obtained by reacting chlorophosphite, {-OC₁₀H₆(μ-S)C₁₀H₆O-}PCl (1) with 2,6-pyridinedimethanol in presence of triethylamine.Treatment of 2 with aqueous solution of H₂O₂ or elemental sulfur resulted in the formation of bis(oxide) or bis(sulfide) derivatives, 2,6-C₅H₃N{CH₂OP(E)(-OC₁₀H₆)(μ-S)(C₁₀H₆O-)}₂ (3, E = O; 4, E = S) in quantitative yield.The 10-membered cationic chelate complex, [RuCl(η⁶-C₁₀H₁₄)η²-2,6-C₅H₃N{CH₂OP(-OC₁₀H₆)(μ-S)(C₁₀H₆O-)}₂-κP,κP]Cl (5) is produced in the reaction between [Ru(p-cymene)(μ-Cl)(Cl)]₂ and bisphosphite 2, whereas the neutral chelate complex, cis-[Rh(CO)Cl{2,6-C₅H₃N{CH₂OP(-OC₁₀H₆(μ-S)C₁₀H₆O-)}₂}-κP,κP] (6) is isolated in the reaction of 2 with 0.5 equiv.of [Rh(CO)₂Cl]₂.Compound 2 on treatment with M(COD)Cl₂ (M = Pd, Pt) produce the chelate complexes, [MCl₂{η²-2,6-C₅H₃N{CH₂OP(-OC₁₀H₆)(μ-S)(C₁₀H₆O-)}₂}-κP,κP] (7, M = Pd;10, M = Pt).Similarly the reaction of bisphosphite 2 with Pd(COD)MeCl affords cis-[PdMe(Cl)η²-2,6-C₅H₃N{CH₂OP(-OC₁₀H₆)(μ-S)(C₁₀H₆O-)}₂-κP,κP] (8).Treatment of 2 with [Pd(η³- C₃H₅)Cl]₂ in the presence of AgClO₄ furnish the cationic complex, [Pd(η³-C₃H₅)η²-2,6-C₅H₃N{CH₂OP(-OC₁₀H₆)(μ-S)(C₁₀H₆O-)}₂-κP,κP]ClO₄ (9). The binuclear complex, [Au₂Cl₂{2,6-C₅H₃N{CH₂OP(-OC₁₀H₆)(μ-S)(C₁₀H₆O-)}₂}-κP,κP] (11) is obtained in the reaction of compound 2 with two equiv. of AuCl(SMe₂), where the ligand exhibits bridged bidentate mode of coordination. All the complexes are characterized by the ¹H NMR, ³¹P NMR, elemental analysis and mass spectroscopy data. The cationic ruthenium complex 5 is proved to be an active catalyst for the hydrogenation of styrene and α-methyl styrene.     

Cyclopalladation of mono-, di- and tribenzylamine by palladium(II) acetate: Influence of bulkiness around the nitrogen atom of benzylamine upon internal metallation

Cyclopalladation of mono-, di- and tribenzylamine has been investigated by reacting the corresponding amines with an equimolar amount of palladium(II) acetate (reaction i), or by heating the corresponding bis-amine complexes [Pd(O₂CMe)₂{(PhCH₂)_nNH_3−n}₂] (n=1, 2) (reaction ii). By the reaction i, all the three amines undergo cyclopalladation. However, in the case of the reaction ii, only the dibenzylamine complex [Pd(O₂CMe)₂{(PhCH₂)₂NH}₂] has been converted into a cyclopalladated complex. The reactivity of the three benzylamines towards cyclopalladation has been discussed in terms of the co-ordinating ability influenced by the bulkiness around the nitrogen atom. Temperature-dependent ¹H-NMR spectra are observed for mononuclear cyclopalladated complexes [Pd(O₂CMe){C₆H₄CH₂N(CH₂Ph)₂–C¹, N}L] (L=PPh₃, AsPh₃) and are attributed to the dissociation of the nitrogen atom in the cyclopalladated chelate ring. A heteroleptic bis-cyclopalladated complex [Pd[C₆H₄CH₂N(CH₂Ph)₂–C¹, N](C₆H₄CH₂NMe₂–C¹, N)] has also been prepared. X-ray crystallographic studies on [{Pd(O₂CMe)[C₆H₄CH₂N(CH₂Ph)₂–C¹, N]}₂] and [Pd[C₆H₄CH₂N(CH₂Ph)₂–C¹, N](C₆H₄CH₂NMe₂–C¹, N)] have been reported.