Presence Of AgPF6 Research Articles

Discrete and polymeric organometallic-organic assemblies based on the diarsene complex [(Cp)2Mo2(CO)4(μ,η2-As2)], AgPF6and N-donor organic molecules

The first mixed-ligand self-assembly reactions of the diarsene complex [Cp2Mo2(CO)4(μ,η2-As2)] and N-donor organic molecules in the presence of AgPF6 allow for the synthesis of two discrete and four polymeric supramolecular aggregates.

Synthesis and structure of bis(indenyl)-rhodium and -iridium complexes

Bis(indenyl)-rhodium and -iridium complexes [(η5-indenyl)M(η5-C9H2R5)]PF6 (2a: M = Rh, R = H; 2b: M = Ir, R = H; 3: M = Rh, R = Me) were synthesized by reactions of iodides [(η5-indenyl)MI2]n (1a,b) with indenes in the presence of AgPF6. The structures of 2aSbF6 and 2bPF6 were determined by X-ray diffraction. They have fully eclipsed geometry, in which the bridgehead carbon atoms of the indenyl ligands are arranged close to each other. Experimental and DFT calculation data showed that the strength of the M−indenyl bond in the bis(indenyl) compounds decreases in the following row: Ir > Co > Rh.

Synthesis and characterization of fullerophosphine–Au(I) complexes

Ligand substitution reaction of the fullerophosphine PPh2(o-C6H4)(CH2NMeCH)C60 (1) with AuCl(SC4H8) affords AuCl(PPh2(o-C6H4)(CH2NMeCH)C60) (2) in good yields. In the presence of AgPF6, compound 2 reacts with 1 to produce [Au(PPh2(o-C6H4)(CH2NMeCH)C60)2]PF6 (3), where the Au(I) ion is coordinated by two molecules of 1 in a dumbbell-shaped feature. On the other hand, compound 1 undergoes a nucleophilic addition to (AuCCPh)n to generate Au(CCPh)(PPh2(o-C6H4)(CH2NMeCH)C60) (4). The structures of 2–4 have been determined by an X-ray diffraction study.

Distinct Reactivity of Mono- and Bis-NHC Silver Complexes: Carbene Donors versus Carbene–Halide Exchange Reagents

The synthesis of N-heterocyclic carbene (NHC) complexes of silver is an established technique for their use as carbene transfer reagents. While it is known that both mono-NHC Ag(I) and bis-NHC Ag(I) complexes are accessible, different reactivities of these species have not been explored synthetically. Whereas the commonly used mono-NHC Ag(I) complexes act as NHC donors only, we found that a bis-NHC Ag(I) complex was capable of transferring one carbene under halide abstraction. This is exemplified in the transformation of P–Cl compounds into the respective imidazolium–phosphines by a bis-NHC Ag(I) complex but not by its corresponding mono-NHC Ag(I) complex. When the bis-NHC Ag(I) complex was allowed to react with [M(cod)Cl]2 (M = Rh, Ir), both NHCs were transferred under chloride abstraction to give [M(cod)(NHC)2]+ exclusively, a reaction which is reported to stop at [M(cod)Cl(NHC)] even with an excess of mono-NHC Ag(I) complex in the presence of AgPF6.

Binding of HgCl2by tripodal ligands controlled by AgPF6: receptors for the PF6−anion

Mercuric chloride can readily enter into the biological cycle where it gets converted into other forms of mercury and causes severe neurotoxic, genotoxic and immunotoxic effects; a number of tripodal ligands have been synthesized that selectively bind mercuric chloride and in the presence of AgPF6, mercury can be removed and supramolecular complexes of the PF6- anion are formed.

Synthesis, characterization and catalytic applications of rhodium(I) organometallics with substituted tertiary phosphines

Organometallics of the type [Rh(COD)(L)Cl] (where, L = carboxyl/formyl/pyridyl tertiary phosphines) have been synthesized by treating the precursor [Rh(COD)Cl]2 with substituted tertiary phosphines. [Rh(COD)(Ph2P-2-C6H4COO)] and [Rh(COD)(Ph2P-CH2COO)] were synthesized by halide abstraction from the precursor [Rh(COD)Cl]2 in the presence of AgPF6 in tetrahydrofuran by involving 2-carboxy phenyl/carboxy methyl group of tertiary phosphines in coordination as bidentate ligands. Similarly, the cationic compounds of the type [Rh(COD)L2]PF6 were also synthesized by treating [Rh(COD)Cl]2 in the presence of AgPF6. All these compounds were characterized by elemental analysis, conductance measurements, IR, 1H, 13C, 31P NMR, mass, and electronic spectral studies. [Rh(COD)(Ph2-P-2-C6H4COOH)Cl] and [Rh(COD)(Ph2-P-2-C6H4COO)] were studied on the catalytic reduction reactions of 2-nitroanisole, 3-nitro anisole, 4-nitroanisole, 2-nitrobenzoicacid, 3-nitrobenzoicacid, 4-nitrobenzoicacid under mild conditions and [Rh(COD)(Ph2-P-2-C6H4COO)] was found to be more efficient than [Rh(COD)(Ph2-P-2-C6H4COOH)Cl].

(η6‐Arene)ruthenium(II) Complexes with Hemilabile η3‐Dicyclohexylvinylphosphine (DCVP) and η3‐Diphenylvinylphosphine (DPVP) Phosphaallyl Ligands: Formation of an Unexpected Trinuclear Complex

The complexes [(η6‐arene)RuCl2(Cy2PCH = CH2)], [arene = MeC6H5, (1a); p‐MeC6H4Me; (2a); p‐MeC6H4CHMe2, (3a); 1,2,4,5‐Me4C6H2, (4a); and C6Me6, (5a)], have been synthesized by reacting [(η6‐arene)RuCl2]2 with dicyclohexylvinylphosphine (DCVP). In the presence of AgPF6, in a 1:1 dichloromethane/acetone solvent mixture the compound [(η6‐C6Me6)RuCl2(Cy2PCH = CH2)] (5a) afforded [(η6‐C6Me6)RuCl(η3‐DCVP) ]PF6 (1b). A similar reaction was conducted with [(η6‐C6Me6)RuCl2(Ph2PCH = CH2)] in an attempt to form [(η6‐C6Me6)RuCl(η3‐DPVP)]PF6 (2b). However, this reaction yielded, instead, the unexpected trinuclear heterobimetallic complex [{(η6‐C6Me6)Ru(μ‐Cl)2(Ph2PCH = CH2)}2Ag](PF6) (3b) the structure of which was determined by X‐ray crystallography. Compound (1b) reacts with phenylisocyanide to form [(η6‐C6Me6)RuCl(η1‐DCVP)(CNPh)]PF6. The complexes have been characterized by 1H, 31P{1H} and 13C{1H} NMR spectroscopy, elemental analyses, cyclic voltammetry, and in some cases [compounds (4a), (1b) and (3b)] by X‐ray crystallography.

Ortho -metalation and carboxylate coordination in the reaction between the dipotassium salt of phthalic acid and Cp * Ir(PMe 3 )Cl 2 : X-ray diffraction structure of Cp*Ir(PMe 3 )[C 6 H 3 (CO 2 )(CO 2 H)

The cyclopentadienyl complex Cp*Ir(PMe3)Cl2 reacts with the dipotassium salt of phthalic acid in the presence of AgPF6 via chloride substitution to give the ortho-metalated compound Cp*Ir(PMe3)[C6H3(CO2)(CO2H)]. This new compound has been isolated by recrystallization and has been characterized in solution by 1H and 13C NMR spectroscopies, and the solid-state structure has been verified by X-ray crystallography. Cp*Ir(PMe3)[C6H3(CO2)(CO2H)] crystallizes in the monoclinic space group P21/c, a = 9.1010(6) A, b = 16.715(1) A, c = 14.3965(9) A, β = 108.24(1)°, V = 2080.0(2) A3, Z = 4, and dcalc = 1.813 mg/m3; R = 0.0276, Rw = 0.0810 for 2730 reflections with I > 2σ(I). Coordination of the benzene ring to the iridium center via one of the carboxylate groups and ortho-metalation of the C–H moiety that was α to the iridium-bound carboxylate group is confirmed.

A cationic allenylideneruthenium(II) complex with two bulky hemilabile phosphine ligands

The allenylidene complex [RuCl(CCCPh2)(κ2-P,O-Cy2PCH2CH2OCH3)2]PF6 (2) has been prepared from [RuCl2(κ2-P,O-Cy2PCH2CH2OCH3)2] (1) and HCCC(OH)Ph2 in the presence of AgPF6. Protonation of 2 with HBF4 in diethyl ether leads to the formation of the dicationic ruthenium carbyne [RuCl(CCHCPh2)(κ2-P,O-Cy2PCH2CH2OCH3)(κ-P-Cy2PCH2CH2OCH3)]2+, which is catalytically less active in olefin metathesis than related species with RuHCl(CCH3) as a molecular unit. The molecular structure of 2 has been determined by X-ray crystallography.

Mononuclear Ruthenium and Hetero-Tetranuclear Ruthenium-Silver Complexes Containing the Unsymmetrical Bidentate Ligands R2P(CH2)nER′2 (n = 1, 2; E = P, As) as Chelating or Bridging Units

The chelate complexes [(p-cym)RuCl(κ2-Ph2PCH2CH2-stBu2)]PF6 (3), [(arene)RuCl(κ2-Ph2PCH2CH2PR2)]PF6 (4, 7, 8) and [(p-cym)RuCl(κ2-iPr2PCH2AstBu2)]PF6 (11) were prepared either from [(arene)RuCl(NCMe)2]PF6 (1, 5) or from [(arene)RuCl2]2 (2, 6), in the presence of NH4PF6 or AgPF6. The stepwise reaction of [(p-cym)RuCl2]2 (2) with Ph2P-CH2CH2PtBu2 and AgPF6 gave the hetero-tetranuclear compound [{(p-cym)RuAg(μ-Cl)2(μ-P1Ru,P2Ag-Ph2P1CH2CH2P2-tBu2)}2](PF6)2 (9), the structure of which was determined by an X-ray crystal structure analysis. The bidentate As,O donor Ph2P(O)CH2CH2AstBu2 also reacted with 2, in the presence of AgPF6, to afford the chelate complex [(p-cym)RuCl{κ2(As,O)-Ph2P(O)CH2CH2AstBu2}]PF6 (10), which was also characterized crystallographically.

Mononuclear Ruthenium and Hetero-Tetranuclear Ruthenium-Silver Complexes Containing the Unsymmetrical Bidentate Ligands R2P(CH2)nER′2 (n = 1, 2; E = P, As) as Chelating or Bridging Units

The chelate complexes [(p-cym)RuCl(κ2-Ph2PCH2CH2AstBu2)]PF6 (3), [(arene)RuCl(κ2-Ph2PCH2CH2PR2)]PF6 (4, 7, 8) and [(p-cym)RuCl(κ2-iPr2PCH2AstBu2)]PF6 (11) were prepared either from [(arene)RuCl(NCMe)2]PF6 (1, 5) or from [(arene)RuCl2]2 (2, 6), in the presence of NH4PF6 or AgPF6. The stepwise reaction of [(p-cym)RuCl2]2 (2) with Ph2PCH2CH2PtBu2 and AgPF6 gave the hetero-tetranuclear compound [{(p-cym)RuAg(μ-Cl)2(μ-P1Ru,P2Ag-Ph2P1CH2CH2P2tBu2)}2](PF6)2 (9), the structure of which was determined by an X-ray crystal structure analysis. The bidentate As,O donor Ph2P(O)CH2CH2AstBu2 also reacted with 2, in the presence of AgPF6, to afford the chelate complex [(p-cym)RuCl{κ2(As,O)-Ph2P(O)CH2CH2AstBu2}]PF6 (10), which was also characterized crystallographically.

Cyclopropanation of Styrene with Ethyl Diazoacetate Catalyzed by Chiral and Achiral Ruthenium 2,6-Bis(imino)pyridyl Complexes

The optically pure 2,6-bis(imino)pyridyl ligands (R)-2,6-bis{1-[α-methylbenzylimine]ethyl}pyridine [(R)-2,6-py(NCHMePh)2] and (S)-2,6-bis{1-(1-naphthyl)ethylimine]ethyl}pyridine [(S)-2,6-py(NCHMeNaph)2] have been prepared by condensation of 2,6-diacetylpyridine with (R)-(+)-α-methylbenzylamine and (S)-(−)-1-(1-naphthyl)ethylamine, respectively. These two ligands and others bearing different substituents on the imine nitrogen atoms (i.e., c-C6H11, C6H5, 2,6-Me2Ph) form, in combination with ruthenium(II) fragments, efficient catalysts for the cyclopropanation of styrene with ethyl diazoacetate (EDA). The catalyst precursors have the general formula RuCl2(PPh3){2,6-py(NR)2} (R = Cy,1; Ph, 6; CHMeNaph, 7; CHMePh, 8). It is generally found that the catalytic activity increases with the size of the substituents on the imine nitrogen atoms. Consistently, the solvento complex RuCl2{2,6-py(N(2,6-Me2Ph2)2}·CH2Cl2 is the most efficient in the series. Best results in terms of activity, diastereoselectivity, and enantioselectivity have been obtained with the chiral precursor 7. In the presence of AgPF6 as cocatalyst, a remarkable improvement in both productivity and chemoselectivity of the cyclopropanation reactions was observed with the catalysts 1 and 6, whereas a substantial decrease in enantioselectivity occurred with the chiral precursors 7 and 8. The carbene complex trans-RuCl2(CHCO2Et){2,6-py(NCy)2} (trans-3) has been isolated upon reaction of 1 with EDA. A kinetic product, cis-RuCl2(CHCO2Et){2,6-py(NCy)2}, was intercepted at low temperature. Compound trans-3 was also obtained by reaction of the ethylene complex RuCl2(η2-H2CCH2)[2,6-py(NCy)2] with EDA. Treatment of trans-3 with AgPF6 led to the formation of the unsaturated complex [RuCl(CHCO2Et){2,6-py(NCy)2}]PF6. The overall reactivity of the Ru(II) 2,6-bis(imino)pyridyl six-coordinate complexes toward either EDA alone or EDA/styrene mixtures suggests that the carbene transfer from EDA to the olefin is apparently mediated by Ru(II) carbene species in an intermolecular fashion. This mechanistic view may not be true for the reactions performed in the presence of a halide scavenger.

Diphosphinito-bridged ruthenium(II) and rhodium(III) complexes with stereogenic metal centers

The bis-4-phosphinito ligands [(p-Ph2POC6H4)2X] (X=O, 1; X=CMe2, 2; X=S, 3) react with [Ru(η6-p-cymene)Cl2]2 to form the binuclear complexes {[Ru(η6-p-cymene)Cl2]2[μ-(p-Ph2POC6H4)2X]} (X=O, 4; X=CMe2, 5; X=S, 6) in good yields as red air stable solids. The crystal structures of 4–6 were determined by X-ray analysis. In acetonitrile and in the presence of AgPF6 (1:1 equiv. with respect to Ru), complexes 4–6 undergo substitution to yield the cationic complexes {[Ru(η6-p-cymene)Cl(CH3CN)]2[μ-(p-Ph2POC6H4)2X]}[PF6]2 (X=O, 7; X=CMe2, 8; X=S, 9), whose stability in solution is very limited. The acetonitrile ligand in complexes 7–9 can be easily replaced by carbon monoxide; the products {[Ru(η6-p-cymene)Cl(CO)]2[μ-(p-Ph2POC6H4)2X]}[PF6]2 (X=O, 10; X=CMe2, 11; X=S, 12) can only be detected in solution under a CO atmosphere and have limited stability. The reaction of [Rh(η5-C5Me5)Cl2]2 with ligands 1–3 results in the formation of the complexes {[Rh(η5-C5Me5)Cl2]2[μ-(p-Ph2POC6H4)2X]} (X=O, 13; X=CMe2, 14; X=S, 15), which have been isolated as red–orange air stable solids. The cationic complexes {[Rh(η5-C5Me5)Cl(CH3CN)]2[μ-(p-Ph2POC6H4)2X]}[PF6]2 (X=O, 16; X=CMe2, 17; X=S, 18), in which the metal atoms are stereogenic centers, have been obtained from the corresponding complexes 13–15, by treatment in CH3CN with AgPF6, and have been characterized only in solution by 31P{1H} NMR spectra and conductivity measurements. On reaction with ligands 1–3, [Rh(η5-C5H5)(CO)2] was converted into the binuclear phosphinito-bridged complexes {[Rh(η5-C5H5)(CO)]2[μ-(p-Ph2POC6H4)2X]} (X=O, 19; X=CMe2, 20; X=S, 21). The reactions of the binuclear complex {[Rh(η5-C5H5)(CO)]2[μ-(p-Ph2POC6H4)2S]} (21) with CH3I, S-(+)-1-bromo-2-methylbutane and racemic PhCH(CH3)Br were also studied. The products were the corresponding acyl derivatives. The reaction of 21 with neat CH3I easily afforded the complex {[Rh(η5-C5H5)(COCH3)I]2[μ-(p-Ph2POC6H4)2S]} (23), whose structural determination by X-ray analysis is also reported.

Living carbocationic polymerization of p-halostyrenes

The total synthesis of diblock copolymers comprising poly(p-chlorostyrene) (PpClSt) and polytetrahydrofuran (PTHF) segments have been accomplished. The syntheses involved the living polymerization of p-chlorostyrene (pClSt) by the 2-chloro-2,4,4-trimethylpentane/TiCl4 initiating system followed by the blocking of tetrahydrofuran (THF) from thesec-benzylic chlorine end-group of PpClSt in the presence of AgPF6 in THF at room temperature and quenching with methanol: A series of PpCISt-b-PTHF diblocks have been prepared. Themolecular weight of the PTHF segments increased with reactiontime. The blocking efficiency (Beff) calculated by1H NMRspectroscopy was nearly 100%.

Cationic Modification of Polychloroprene. II. Homopolymerization of Isobutyl Vinyl Ether and Synthesis and Characterization of Poly(chloroprene-g-Isobutyl Vinyl Ether)

Abstract It was discovered that allylic chlorines [(CH3)2C=CHCH2Cl, CH2[dbnd]CHCH(Cl)CH3] in the presence of AgPF6 are efficient initiators of isobutyl vinyl ether polymerization. The transitory allyl cation formed during the precipitation of AgCl is presumed to be the initiating entity. This knowledge was exploited in the subsequent synthesis of the graft copolymer poly(chloroprene-g-isobutyl vinyl ether). In this synthesis, allylic chlorines in polychloroprene function as graft initiating sites in conjunction with AgPF6. Grafting efficiencies are low due to the great propensity for chain transfer of isobutyl vinyl ether polymerization. Pure grafts have been obtained by selective solvent extractions and were characterized by gravimetry, osmometry, 1H-NMR and DSC. Poly(isobutyl vinyl ether) branch frequency was 7–12 in graft copolymerization carried out at 15 to 0°C.

Thermal and photochemical cationic polymerisations induced by AgPF6 in the presence of free radical initiators

Cationic polymerisations of n-butylvinylether, tetrahydrofuran and a typical bis-epoxide are readily induced in the presence of AgPF6 by thermal and photochemically active sources of free radicals.