Ramón Yáñez

Organometallic rhodium (I) complexes with 1-alkylaminopyrazole ligands

Abstract New bidentate NN ′ and tridentate NN ′ N 1-alkylaminopyrazoles were synthesized and characterized by elemental analyses and spectroscopic methods. The reaction of [RhCl(cod) 2 ] (cod=cycloocta-1,5-diene) with one equivalent of L 1-alkylaminopyrazoles afforded Rh 2 Cl 2 (L)(cod) 2 complexes (L= NN ′ and NN ′ N ). These rhodium (I) compounds were studied by IR, 1 H- and 13 C-NMR and liquid mass (with electrospray and APCI interfaces) spectrometries. The 1 H-NMR spectra and molar conductances of these complexes suggested the presence of 1:1 electrolyte species, [Rh(L)cod] + [RhCl 2 (cod)] − , in solution. A combined electrospray and APCI liquid mass spectroscopy study confirmed the presence of both [Rh(L)cod] + and [RhCl 2 (cod)] − species in solution but the existence of a neutral molecular form of complexes in solution could not be demonstrated.

Synthesis of a New Potentially Hemilabile Ligand: 1-[2-(Diphenylphosphanyl)ethyl]-3,5-dimethylpyrazole, and Comparison of Its Bonding Properties with the Related 1-[2-(Ethylamino)ethyl]-3,5-dimethylpyrazole Ligand toward RhI

The new ligand 1-[2-(diphenylphosphanyl)ethyl]-3,5-dimethylpyrazole (2) has been prepared by the reaction of 1-(chloroethyl)-3,5-dimethylpyrazole and PPh2Li. The bidentate N,N ligand 1-[2-(ethylamino)ethyl]-3,5-dimethylpyrazole (1) and 2 react with [Rh(COD)(THF)2][BF4] to give [Rh(COD)(1)][BF4] (3) and [Rh(COD)(2)][BF4] (4), respectively. Substitution of 1,5-cyclooctadiene with carbon monoxide in the latter complexes generates [Rh(CO)2(1)][BF4] (5) and

The formation of [RuCl(p-cymene)(Me2HPz)(PPh2OR)]Cl (Me2HPz=3, 5-dimethylpyrazole; R=H, Me and p-Tol) complexes from the cleavage of the P-N bond of a P-coordinated P(Me2Pz)Ph2 ligand by ROH molecules in a ruthenium(II) complex. Crystal structure of [RuCl(p-cymene)(Me2HPz)(PPh2OH)]Cl

Abstract The complex [RuCl2(p-cymene)]2 reacts with 1-(3,5-dimethyl)pyrazolyldiphenylphosphine (P(Me2Pz)Ph2) to give the complex RuCl2(p-cymene)(P(Me2Pz)Ph2). This compound reacts with ROH molecules (R=H, Me and p-Tol) to give [RuCl(p-cymene)(Me2HPz)(PPh2OR)]Cl (R=H, Me and p-Tol) complexes, which contain both Me2HPz and PPh2OR coordinated molecules.

Synthesis and reactivity of 3,5-dimethyl-4-aminomethylpyrazole ligands. An entry to new water-soluble pyrazolate rhodium(I) complexes

Abstract The new pyrazoles 3,5-dimethyl-4-(ethylamino)methylpyrazole (HL1) and 3,5-dimethyl-4-(isopropylamino)methylpyrazole (HL2), both containing aminoalkyl groups at position 4 have been prepared by aminoalkylation of 3,5-dimethylpyrazole and by the reaction between 1-chloromethyl-3,5-dimethylpyrazolium chloride and NH2R amines. The reaction between HL1, HL2 and [RhCl(COD)]2 resulted in complexes of formula [Rh2(HL1)2(COD)2]Cl2 (1) and [Rh2(HL2)2(COD)2]Cl2 (2), which contained the pyrazole ligands in the ‘zwitterionic’ pyrazolate-ammonium forms. The X-ray structure analysis of 2 confirmed the neutral nature of bridging-pyrazolate ligands and revealed that 1 and 2 belonged to the [Rh2(Pz)2L2] family of compounds. The same reaction with two equivalents of NaOMe resulted in neutral pyrazolate complexes [Rh2(L1)2(COD)2] (5) and [Rh2(L2)2(COD)2] (6). The reaction between both cationic and neutral pyrazolate complexes and a 1:1 CO–H2 mixture (20 atm) led to the dinuclear pyrazolate-bridged tetracarbonyl compounds 3, 4, 7 and 8 in good yields. Tetracarbonyl complexes 3 and 4 were not isolated in pure state. All the complexes synthesized are soluble in polar solvents such as water.

Synthesis of Ru(II) complexes of the new 1-[(P-diphenyl)-2-phosphinoethyl]-3,5-dimethylpyrazole ligand and study of their reactivity toward terminal alkynes

Abstract The reaction between [RuCl 2 (PPh 3 ) 3 ] and one or two equivalent amounts of 1-[(P-diphenyl)-2-phosphinoethyl]-3,5-dimethylpyrazole ( 1 ) in dichloromethane gave [RuCl 2 (PPh 3 )( 1 )] ( 2 ) or [RuCl 2 ( 1 ) 2 ] ( 3 ), respectively, in good yields. Activation of propargylic alcohol derivatives by 3 in refluxing dichloromethane and in the presence of NaBPh 4 lead to the new allenylidene ruthenium complexes [RuCl( 1 ) 2 (CCCPhCH 3 )][BPh 4 ] ([ 4 ][BPh 4 ]) and [RuCl( 1 ) 2 (CCCPh 2 )][BPh 4 ] ([ 5 ][BPh 4 ]). The reaction between 3 and phenylacetylene in dichloromethane and in the presence of KPF 6 affords the vinylidene complex [RuCl( 1 ) 2 (CCHPh)][PF 6 ] ([ 6 ][PF 6 ]). The X-ray diffraction studies of 2 , 3 , and [ 5 ][BPh 4 ] are reported.

Conjugate additions to alkynylalkoxycarbenemetal (Cr or W) complexes

Abstract The addition of different nucleophilic compounds (aliphatic and aromatic alcohols, thiols and phosphines) to alkynylalkoxycarbene complexes has been studied. The reaction with smaller nucleophiles proceeds readily and regioselectively at the β-carbene position. With more substituted nucleophiles the reaction rate slowed down considerably. Addition of a catalytic amount of DBU (1,8-di-azabicyclo[5.4.0]undec-7-ene]) speeded up the reaction and improved the E/Z ratio.

Synthesis and structure of diiron compounds containing both diphenylphosphido and ethenyl bridges. Crystal structure of [Fe2(CO)6(μ-PPh2(μ-CPhCPhH)]

Abstract Treatment of [Fe2(CO)6(μ-CO)(μ-CRCR′H)]− (R = R′ = Ph, H an RPh, R′ = Me) with PPh2Cl in CH2Cl2 in the presence of TlBF4 gives complexes of the type [Fe2(CO)6(μ-PPh2)(μ-CRCR′H)], containing both phosphido and ethenyl bridges. Similar products were isolated from the reaction of [Fe2(CO)6(μ-CO)(μ-PPh2)]− with CF3COOH and acetylenes. The crystal structure of the complex [Fe2(CO)6(μ-PPh2)(μ-CPHCPhH)] is reported.

THE FORMATION OF ALKENEDITHIOCARBOXYLATE AND ALKENECARBOXYLATE LIGANDS BY INSERTION OF CS2 AND CO2 INTO RUTHENIUM(II)-ALKENYL BONDS

Abstract The unsaturated alkenyl complexes Ru(CO)Cl(RCCHR′)(PPh3)2 react with CS2 and CO2 to give Ru(CO)Cl(S2CRCCHR′)(PPh3)2 and Ru(CO)Cl(O2CRCCHR′)(PPh3)2 complexes, respectively. The products are hexacoordinated-ruthenium(II) complexes containing alkenedithiocarboxylate or alkenecarboxylate ligands η2-coordinated to metal. In these reactions CS2 and CO2 insert into rutheniumalkenyl bonds to form new chelated ligands. The structures of products and the nature of the alkenedithiocarboxylate and alkenecarboxylate ligands have been established from spectroscopic data (IR, 1H and 31P NMR).

Synthesis of dinuclear alkenyl-bridged iron—nickel and diiron complexes. The crystal structure of [Fe2(CO)4(C5H5)(μ-CO)(μ-CPhCPhH)]

Abstract The reaction of the anions [Fe(η 3 -R 1 HCCR 2 CO)(CO) 3 ] − (R 1  H, R 2 CO 2 Me and CO 2 Et; R 1  R 2  CO 2 Me) with [Ni(C 5 H 5 )(PPh 3 )Br] gives the complexes [FeNi(CO) 3 (C 5 H 5 )(PPh 3 )(μ-R 2 CCH 2 )] (R 2  CO 2 Me ( 1 ) and CO 2 Et( 2 )) and [FeNi(CO) 2 (C 5 H 5 )(PPh 3 )(μ-MeO 2 CCC(H)CO 2 Me)] ( 3 ). Complexes 1 and 2 have been also obtained by heating mixtures of [PPh 4 ][HFe(CO) 4 ] − , R 1 CCR 2 , and [Ni(C 5 H 5 )(PPh 3 )Br] in THF. Use of the [HFe(CO) 4 ] − /PhCCPh/M(C 5 H 5 )L x X (M  Ni, L x  PPh 3 and M  Fe, L x  (CO) 2 ) system was successful for the synthesis of [FeNi(CO) 3 (C 5 H 5 )(PPh 3 )(μ-CPhCCPhH)] ( 4 ) and [Fe 2 (CO) 4 (C 5 H 5 )(μ-CO)(μ-PhCCPhH)] ( 5 ) complexes. The structure of 5 was determined by an X-ray diffraction study.

Carbon-carbon bond formation at diiron centres V. Synthesis of anionic vinyl-bridged diiron complexes and their reactivity toward alkynes☆

Abstract The reaction of acetylenes with [PPh4][HFe(CO)4] in the presence of Fe2(CO)9 in THF solution leads to the formation in high yields of the complexes [PPh4][Fe2(CO)6(μ-CO)(μ-CR1CR2H)] where R1 = Ph and R2 = H; R1 = R2 = Ph; R1 = tBu and R2 = H; R1 = SiMe3 and R2 = H; R1 = CO2Me and R2 = H. The complex [PPh4][Fe2(CO)6(μ-CO)(μ-CHCRH)] with R = H or Ph) reacts with the alkynes R3CCR3 (R3 = Ph, C(O)OMe, CF3) in a different way from that previously observed for the alkyne with R3 = Ph. The reaction involves insertion of the alkyne into the iron-carbon σ bond of the alkenyl bridge, to give [PPh4][Fe2(CO)6(μ-CR3CR3CHCHR)] complexes (R = H). Depending on the R3 group, two modes of bonding of the organic bridge have been observed, μ-η2,η2 (R3 = Ph) and μ-η3,η1 (R3 = CF3). The complexes have been obtained from these reactions [PPh4][Fe2(CO)6(μ-CR3CR3C(O)CHCH(R)] with R3 = Ph; R = H; R3 = CF3 or C(O)OMe; R = Ph.