M. Carmen Ramírez de Arellano

Synthesis and Reactivity of 2-Aminophenylpalladium(II) Complexes: Insertion Reactions of Oxygen and Carbon Monoxide into Carbon−Palladium Bonds—New Examples of “Transphobia”

Insertion of CO into 2-aminophenylpalladium complexes leads to 2-aminobenzoylpalladium derivatives. When these compounds are forced to coordinate a carbon donor and a phosphane ligand in the trans position, a C−P coupling process or an insertion of oxygen occurs (see scheme). In this case, a dinuclear palladium complex containing a bridging anthranilato ligand is isolated.

New palladium(II) complexes with bis(pyrazol-1-yl)alkanes

Abstract The replacement of chloride ligands in [Pd(NN)Cl2] (NN=bpzm: bis(pyrazol-1-yl)methane, bpzm*: bis(3,5-dimethylpyrazol-1-yl)methane) by a weak donor ligand such as acetonitrile has been achieved by treating the dichloro complexes with AgClO4 in this solvent. The reactivity of the new precursors [Pd(NN)(CH3CN)2][ClO4]2 towards a variety of neutral N- and P-donor ligands L (pyridine, triphenylphosphine, triethylphosphine) or L2 (1,2-bis(diphenylphosphino) ethane, ethylenediamine, N,N,N′,N′-tetramethylethylenediamine, 2,2′-bipyridine, o-phenylenediamine) has been studied. When chloride abstraction from [Pd(NN)Cl2] is carried out in Me2CO/H2O, the cationic hydroxo-bridged dimeric complexes [(NN)Pd(μ-OH)2Pd(NN)]2+ are isolated as their perchlorate salts. The hydroxo complexes react with the protic electrophiles H(LL) (acetylacetone, salicylaldehyde and 2-pyrrol carbaldehyde) in a 1:2 molar ratio to give the corresponding mononuclear complexes [Pd(NN)(LL)][ClO4]. The 13C and 1H NMR assignments have been made on the basis of NOE studies and 1H–1H COSY and 1H–13C HETCOR experiments. The structures of [Pd(bpzm)(tmeda)][ClO4]2 and [Pd(bpzm*)(sal)][ClO4] have been determined by single-crystal X-ray diffraction studies; in both complexes the bis(pirazolyl)alkanes act as chelating ligands with coordination around the palladium atom slightly distorted from the square-planar geometry.

Investigative studies on the formation of the imidazo [4′,5′:3,4]pyrido[2,3-b]indole ring: Formal synthesis of the alkaloids grossularines-1 and 2. X-Ray crystal structures of 5-indol-3-yl-imidazole and bisimidazocarbazole derivatives

Abstract Reactions of several 2,3-disubstituted indoles, bearing a chlorine or amino function at position 2 and an 1,2-dicarbonyl group or bromoacetyl substituent at position 3, with N,N-dimethylguanidine is reported. In general, 5-indol-3-yl imidazole derivatives are found to be the reaction products, however when the 3-bromoacetyl-2-tertbutoxycarbonylaminoindole is used the 2-dimethylamino-4-hydroxy-6-methoxymethyl-3H-imidazo[4′,5′:3,4]pyrido[2,3-b]indole is obtained through a step-wise formation of the pyridine and the imidazole rings. The crystal molecular structure of 5.H2O and 7 . HBr.H 2 O . 3 2 EtOH have been determined by X-Ray analysis. The water molecules in 5. H2O act as both donor (OH…N) and acceptor (NH…O) and are responsible for the formation of strands along the b axis.

Synthesis and Structure of P,N-Heterodifunctional Ferrocene Ligands and their Transition Metal Complexes for Palladium-Catalyzed Aryl Amination Reaction

Abstract The Staudinger reaction of the β-ferrocenylvinylazide 1 with di- and triphosphines provided a new range of P,N-heterodifunctional ferrocene ligands bearing an iminophosphorane and at least a diphenylphosphino group; reactivity towards Pd (II) and the ability of the resulting complexes for palladium catalyzed aryl amination reaction is described.

Reactivity of the di-μ-hydroxo-complexes [{Pd(NN)}2(μ-OH)2][ClO4]2 (NN=bis(pyrazol-1-yl)alkanes) towards protic electrophiles. Hydration of coordinated nitriles at a palladium(II) site

Abstract The hydroxo-complexes [{Pd(μ-OH)(NN)}2][ClO4]2 (NN=bpzm:bis(pyrazol-1-yl) methane: a-compounds, bpzm*:bis(3,5-dimethylpyrazol-1-yl)methane; b-compounds) react with a wide variety of weak protic electrophiles H(LL) in a 1:2 molar ratio to give the mononuclear cationic palladium(II) derivatives of general formula [Pd(LL)(NN)][ClO4] [LL=2-pyridine-methoxo (OCH2-py) (1a,b); picolinate (pic) (2a,b); 8-hydroxiquinolinate (oxin) (3a,b)] or the dinuclear complexes [{Pd(NN)}2(μ-ox)][ClO4]2 [ox=oxalate: (4a,b)] and [{Pd(μ-LL)(NN)}2][ClO4]2 [LL=pyrazolate (pz) (5a,b); p-thiocresolate (SC6H4Me-p) (6a,b); triazolate (tz) (7b); thiophenolate (SPh) (8b)] when reacting with oxalic acid, azoles or thiols in the same molar ratio. In a related reaction, deprotonation of secondary amines by the hydroxo-complexes in the presence of carbon disulfide leads to the corresponding dithiocarbamate complexes [Pd(S2CNR2)(NN)][ClO4] [R=Me (9a,b), Et (10a,b) C5H10 (11a,b)]. The hydroxo complexes also promote the nucleophilic addition of water to pyridine-2-carbonitrile and mononuclear complexes containing pyridine-2-carboxamidate ligands are formed (12a,b). The new compounds have been characterized by partial elemental analyses, conductance measurements and spectroscopic (IR, 1H and 13C NMR) methods. The crystal structures of compounds 6b and 11a have been determined by X-ray diffraction analysis.

Reactions of the hexaruthenium cluster anions [Ru6C(CO)16]2− and [Ru6(CO)18]2− with Au2{Ph2PCH2PPh2}Cl2: crystal and molecular structures of Ru6C(CO)16Au2{Ph2PCH2PPh2} and Ru5(CO)15Au2{Ph2PCH2PPh2}

Abstract The reaction of the carbido dianion [Ru 6 C(CO) 16 ] 2− with Au 2 {Ph 2 PCH 2 PPh 2 }Cl 2 , in dichloromethane, in the presence of TIPF 6 , affords the neutral cluster Ru 6 C(CO) 16 Au 2 {Ph 2 PCH 2 PPh 2 } ( 1 ) in 90% yield. An X-ray analysis of 1 shows that the octahedral ruthenium core has remained intact, and that the two Au atoms of the chelating gold phosphine bridge two adjacent edges of one of the triangular faces of the Ru 6 octahedron. In marked contrast, the reaction of the non-carbido dianion [Ru 6 (CO) 18 ] 2− with Au 2 {Ph 2 PCH 2 PPh 2 }Cl 2 under similar reaction conditions leads to the breakdown of the octahedral ruthenium core and the formation of Ru 5 (CO) 15 Au 2 {Ph 2 PCH 2 PPh 2 } ( 2 ) in ca . 50% yield. The X-ray analysis of 2 shows that the ruthenium atoms adopt a trigonal bipyramidal framework with the Au atoms of the Au 2 {Ph 2 PCH 2 PPh 2 } ligand μ 3 - capping adjacent faces of the trigonal bipyramid in a manner not previously observed for mixed ruthenium-gold clusters.

Synthesis and characterisation of the chloride-bridged copper–ruthenium cluster dianion [{Ru6Cu2C(CO)16}2Cl2]2–

The mixed-metal ruthenium–copper cluster dianion [{Ru6Cu2C(CO)16}2]2–1 has been synthesised in quantitative yield from [Ru6C(CO)16]2– and CuCl; the crystal structure of the [N(PPh3)2]+ salt shows that the two Ru6 octahedra are linked by a rectangular planar arrangement of copper atoms two opposite edges of which are bridged by chlorine atoms.

Insertion of internal acetylenes into orthopalladated α-methylbenzylamine. Crystal structure of [Pd{C(Ph)C(Ph)C(Ph)C(Ph)C6H4CH(Me)NH2}Br]

The complex [Pd{C6H4CH(Me)NH2}(Me2CO)2]ClO4 reacted with diphenylacetylene to give [Pd2(η5-C5Ph5)2(µ-η2-PhCCPh)]. A pathway for this reaction is suggested. Species related with the postulated intermediates can be isolated starting from [{Pd[C6H4CH(Me)NH2](µ-Br)}2] which reacts with disubstituted alkynes (RCCR, R = CO2Me or Ph) to afford [Pd{C(R)C(R)C(R)C(R)C6H4CH(Me)NH2}Br](R = CO2Me 1a or Ph 1b) through a double insertion of the alkyne into the Pd–C bond. Complex 1a reacted with 1 equivalent of MeO2CCCCO2Me to give the tri-insertion reaction product 2. These are the first products of alkyne insertion into a cyclopalladated primary amine. Neutral ligands, such as pyridine (py) or CO, can break the Pd–π-olefinic bond in 1a to give the corresponding adducts [Pd{C(R)C(R)C(R)C(R)C6H4CH(Me)NH2}Br(L)](R = CO2Me; L = py 3 or CO 4). Complexes 1a and 1b reacted with AgClO4(1 : 1) in acetone to afford AgBr and [Pd{C(R)C(R)C(R)C(R)C6H4CH(Me)NH2}(solv)]ClO4(R = CO2Me, solv = H2O 5a; R = Ph, solv = Me2CO 5b). The reaction of complex 1a with AgClO4(1 : 1) and excess of pyridine gave the cationic complex [Pd{C(R)C(R)C(R)C(R)C6H4CH(Me)NH2}(py)2]ClO46(R = CO2Me). The crystal structure of complex 1b has been determined by X-ray diffraction. The palladium atom is bonded to Br, N, C(1) and to the midpoint of the C(3)–C(4) double bond in a distorted square-planar geometry.

One-Pot Synthesis of 1,4-Dichlorophenazines

Abstract An efficient, generally applicable one-pot method for the synthesis of 1,4-dichlorophenazines has been established. The method is based on the use of 3,3,6,6-tetrachloro-1,2-cyclohexanedione 2 as a synthetic equivalent of 3,6-dichloro-1,2-benzoquinone 1. The reaction of 2 with primary 1,2-arylidenediamines followed by treatment with pyridine provides the title compounds in nearly quantitative yields. 1,1,4,4-Tetrachloro-1,2,3,4-tetrahydrophenazines are isolable intermediates. The crystallographic X-ray structure of 7,7′-Bis(1,1,4,4-tetrachloro-1,2,3,4-tetrahydrophenazine) 7 has been determined.

Crown ethers derived from cyclohexane. Influence of their stereochemistry in complexation and transport

Abstract Crown ethers derived from cyclohexane have been prepared. The trans stereochemistry of the substituents on the carbocyclic ring makes that only one conformation can complex cations. The influence of the stereochemistry in complexation has been studied.