Amelia Santos

Insertion reactions of acetylenes with hydridocarbonyl-chlorotris(triphenylphosphine)ruthenium(II). X-ray structure of carbonylchloro(cis-1,2-diphenylethenyl)bis(triphenylphosphine)ruthenium(II)

Abstract Reactions between Ru(CO)ClH(PPh 3 ) 3 and phenylacetylene, pent-1-yne and diphenylacetylene in CH 2 Cl 2 give the red crystalline alkenyl species Ru(CO)Cl-(RCHR′)(PPh 3 ) 2 (R = H, R′ = C 3 H 7 , Ph; R = R′ = Ph), which can be regarded as resulting from elimination of one phosphine molecule and insertion of the alkyne into the RuH bond. The reaction with phenylacetylene in MeOH/CH 2 Cl 2 ( 1 1 ) gives the yellow crystalline complex Ru(CO)Cl(PhCCH 2 )-(PPh 3 ) 3 , seemingly resulting from a simple insertion of the alkyne into the RuH bond. The complexes have been characterized by elemental analysis and 1 H NMR and IR spectroscopy. The molecular structure of Ru(CO)Cl(PhCCHPh)(PPh 3 ) 2 , determined by X-ray diffraction, can be described as a distorted trigonal bipyramidal species, in which the phosphine molecules occupy the axial positions and the alkenyl ligand has the phenyl groups in a cis configuration. Similar molecular structures are probable for the other red complexes. The yellow complex derived from phenylacetylene seems to be a six-coordinate species, in which two phosphine molecules are respectively cis - and trans -coordinated with respect to the alkenyl ligand.

Insertion reactions of dimethyl acetylenedicarboxylate with alkenylruthenium complexes of the type [Ru(CO)Cl(R′CCHR)(PPh3)2]. The crystal structure of [Ru(CO)Cl{MeOOCCC(CO2Me)-CHCHCMe3}(PPh3)2]

Abstract Reactions between alkenylruthenium complexes of the type [Ru(CO)Cl(R′ CCHR)(PPh3)2] (R′ = R = H, Me, Ph; R′ = H, R = C3H7, CMe3, Ph) with dimethylacetylenedicarboxylate give mixed bis-insertion complexes of formula [R u(CO)Cl{MeOO CCC(CO2Me)CR′  CHR}(PPh3)2], which have been isolated and characterized only in the case of terminal alkyne derivatives (R′ = H). This reaction is competitive with the simple displacement reaction of the non-activated acetylene by dimethyl acetylene-dicarboxylate. The complexes were characterized by elemental analysis and 1H NMR and IR spectroscopy. The molecular structure of [R u(CO)Cl{MeOO CCC(CO2Me)CHCHCMe3})2], determined by X-ray diffraction, can be regarded as a distorted octahedral species, in which the butadienyl ligand acts as bidentate through an additional CO Ru bond involving a carboxylate oxygen atom, the atom pairs (P,P), (Cl,C) and (O,C) being in trans positions.

Phenylacetylene dimerization promoted by ruthenium(II) complexes

Abstract The complex Ru(CO)(CH CHPh)Cl(C 5 H 5 N)(PPh 3 ) 2 and related alkenyl complexes react in methanol or ethanol to give ( E, E )-1,4-diphenylbuta-1,3-diene and the ruthenium(II) hydride Ru(CO)H(Cl)-(C 5 H 5 N)(PPh 3 ) 3 . Further reaction of this hydride with the butadiene results in 1,2-reduction to yield ( E )-1,4-diphenyl-1-butene. However, the reaction of phenylacetylene with catalytic amounts of ruthenium hydrides gave the dimer ( Z )-1,4-diphenylbuten-3-yne. On the other hands, the reaction of 1,2-diphenyl-ethenylruthenium(II) derivatives in methanol or ethanol gave trans -stilbene rather than the butadiene. Several deuteriation experiments were performed in order to elucidate the mechanism of formation of ( E, E )-1,4-diphenylbuta-1,3-diene and ruthenium hydride from the corresponding alkenyl complexes.

Reactions of alkenyl and alkynyl ruthenium(II) complexes with isocyanides: Synthesis of α, β-unsaturated η1-acylruthenium(II) complexes and X-ray structure of [Ru(CCPh)(CN+Bu)3(PPh3)2]PF6

Abstract Reaction of (E)-alkenyl complexes Ru(CO)Cl(CHCHR)(PPh3)2 and Ru(CO)Cl(CHCHR) (PPh3)2L (L  Me2Hpz, py) with an excess of an isocyanide R′NC (R′tBu or cyclohexyl (Cy)) gives (E)-α,β-unsaturated-η1-acyl complexes [Ru(COCHCHR)(CNR′)3(PPh3)2]Cl in good yield. The corresponding reactions with 1 equivalent of isocyanide give the hexacoordinate complexes Ru(CO)Cl(CHCHR)(CNR′)(PPh3)2. The reaction of [Ru(CO)(CHCHR)(NCMe)2(PPh3)2]PF6 with tBuNC also affords η1-acyl complexes [Ru(COCHCHR)(CNtBu)3(PPh3)2]PF6. On the other hand, treatment of alkynyl complexes [Ru(CO)(CCR)(py)2(PPh3)2]PF6 with an excess of tBuNC under forcing conditions promotes substitution of CO and pyridine ligands by the isocyanide, yielding alkynyl derivatives [Ru(CCR)CNtBu)3(PPh3)2]PF6. An X-ray diffraction study of one of the complexes (R  Ph) confirmed the proposed structure. Similarly, reaction of the alkynyl complexes with CO gives only the ligand-substitution products [Ru(CO)2(CCR)(py)(PPh3)2][PF6]. The reaction of (E)-alkenyl ruthenium(II) complexes with alkyl isocyanides proceeds under mild conditions to yield (E)-α,β-unsaturated-η1-acyl ruthenium(II) complexes. Although these complexes are obtained from intermediates with both CO and isocyanide ligands, exclusive migratory insertion of the alkenyl ligand into the RuCO bond is observed. The related alkynyl carbonyl ruthenium(II) complexes do not undergo insertion, reacting sluggishly with the isocyanides to yield new alkynyl ruthenium complexes in which the carbonyl ligand has been replaced by an isocyanide ligand. The corresponding reaction with CO leads to dicarbonyl alkynyl complexes by substitution of the pyridine trans to the alkynyl ligand.

Reactions of cationic hydrido complexes [Ru(CO)H(MeCN)2(PPh3)2]A (A ClO4, PF6) with alkynes. The crystal structure of [Ru(CO) (MeOOCCCHCOOMe) (MeCN)2(PPh3)2]ClO4

Abstract Reactions of [Ru(CO)H(MeCN)2(PPh3)2]A with mono- and di-substituted acetylenes give the alkenyl derivatives [Ru(CO)(RCCHR′)(MeCN)2(PPh3)2]A (A  ClO4, R  H; R′  C3H7, CMe3, Ph, COOMe; R  R′  COOMe; A  PF6, R  R′  Ph) resulting from a cis-insertion of the alkyne into the RuH bond. The reaction of the perchlorate complex with diphenylacetylene yields alkenyl chlororuthenium derivatives resulting from the unexpected reduction of the perchlorate anion to chloride. The crystal structure of [Ru(CO)(MeOOCCCHCOOMe)(MeCN)2(PPh3)2]ClO4 has been determined by X-ray crystallography (orthorhombic, P212121, a 14.498(1), b 15.080(1), c 22.677(2) A). In this cationic complex both phosphine and acetonitrile molecules and, consequently, the carbonyl and alkenyl ligands are mutually trans, whereas in the other complexes only the phosphine ligands are in trans disposition, as inferred from 1H NMR spectroscopic data.

Reaction of alkenyl-ruthenium(II) Ru(CO)Cl(RC=CHR')(PPh3)2 complexes with CO. Formation of dicarbonyl complexes or η2-acyl complexes depending on the R and R' groups

Reaction of the coordinatively unsaturated alkenyl complexes Ru(CO)Cl(RC=CHR′)(PPh3)2 with CO gives two types of compounds, the dicarbonyl complexes Ru(CO)2Cl(RC=CHR′)(PPh3)2 (R = H, R′ = H, Ph, tBu, SiMe3, CO2Me or CO2Et and R = R′ = CO2Me) and the η2-acyl complexes Ru(CO)Cl(η2-O=CCR=CHR′)(PPh3)2 (R = R′ = Me, Et and Ph). The reaction of sodium proprionate with the Ru(CO)Cl(η2-O=CCMe=CHMe)(PPh3)2 complex yields a new product containing both η2-alkeneacyl and η2-propionate ligands. The structures of the new complexes were established from their IR and NMR spectra.

Bis-insertion reactions of Ru(CO)HCl(PPh3)3 with methyl propiolate. The unexpected formation of (methoxycarbonylethenyl)triphenylphosphonium chloride

Abstract The reaction of Ru(CO)HCl(PPh 3 ) 3 with methyl propiolate gives two bis-insertion derivatives resulting from a head-to-head dimerization reaction. The eliminated triphenylphosphine ligand reacts with the alkyne to give an actylidephosphonium salt, which brings about substitution of the chloride ligand of Ru(CO)Cl(CHCHCOOMe)(PPh 3 ) 2 by acetylide. The resulting phosphonium salt, methoxycarbonylethenyltriphenylphosphonium chloride has been characterized as the methanol adduct 2-methoxy-2-methoxycarbonylethyltriphenylphosphonium chloride.

Ruthenium‐Capping of Di‐ and Tetraethynylbiphenyls

The di- and tetraalkynyl biphenyls 3 and 5 have been synthesized from the tetrabromo derivative 1 by using Pd-catalyzed cross-coupling reactions. The reaction of 3 or 5 with cis-[RuCl2(dppe)2] (8) affords vinylidene ruthenium complexes, which were deprotonated with Et3N to give the terminal σ-alkynylruthenium derivatives 9−12. The reaction of 3 or 5 with [Ru(CO)ClH(PPh3)3] (13) gave the corresponding di-σ-alkenyl ruthenium complexes 14 and 15.

Synthesis of RuII hydride and alkenyl amidine complexes. The crystal structure of [Ru(CO)(CH=CHCMe3){NH=C(Me)(Me2pz)}(PPh3)2]PF6

Abstract The reaction of the ruthenium hydrides [Ru(CO)H(R 1 CN) 2 (PPh 3 ) 2 ]A (A = ClO 4 or PF 6 ) (R 1 = Me or CH 2 Ph) or the alkenyl derivatives [Ru(CO)(CH=CHR 1 ()R 2 CN) 2 )(PPh 3 ) 2 ]PF 6 (R 1 = CMe 3 , Ph; R 2 = Me or CH 2 Ph) with pyrazole or 3,5-dimethylpyrazole gives the ruthenium(II) pyrazolylamidine complexes [Ru(CO)H{NH=C(R 1 )(het)}(PPh 3 ) 2 ]A or [Ru(CO)(CH=CHCR 1 ){NH—C-(R 2 )(het)}(PPh 3 ) 2 ]A, respectively (het = pz or Me 2 pz). The stereochemistry of the resulting complexes has been determined by NOEDIFF experiments and by the X-ray structure determination of [Ru(CO)(CH=CHCMe 3 ){NH=C(Me)(Me 2 pz)}(PPh 3 ) 2 ]PF 6 .

Reaction of alkenyl carbonyl ruthenium(II) complexes with t-butyl isocyanide. Synthesis of η1-acylruthenium(II) complexes by intramolecular CO insertion

Abstract Reaction of Ru(CO)Cl(CHCHR)(PPh 3 ) 2 or Ru(CO)Cl(CHCHR)(PPh 3 ) 2 L (L = py, Me 2 Hpz) with 1 equivalent of t-butyl isocyanide gives the alkenyl derivatives Ru(CO)Cl(CHCHR)(PPh 3 ) 2 (t-BuNC). When an excess of isocyanide is used, further reaction results in intramolecular CO insertion to yield η 1 -acyl complexes [Ru(COCHCHR) (t-BuNC) 3 (PPh 3 ) 2 ]Cl. Related complexes were obtained from [Ru(CO)(CHCHR)(MeCN) 2 (PPh 3 ) 2 ]PF 6 and an excess of isocyanide.