Reaction Of AgBF4 Research Articles

Silver(I) complexes based on cyclic arsine ligands: Synthesis, structure and bioactivity

Silver(I) complexes containing cyclic arsine ligands, namely 10-arylphenoxarsines L1 – L4 and 10-phenyl-5,10-dihydrophenarsazine L5, have been synthesized by the reactions of AgBF4 with the cyclic arsine ligands in different molar ratios. All complexes are characterized by 1H NMR, mass-spectrometry, elemental analysis, and X-ray diffraction. All complexes exhibit moderate to enhanced antimicrobial activity against both Gram-positive and Gram-negative bacteria, fungi as well as anticancer activity against M−HeLa and HuTu 80 cell lines.

Introducing the Perfluorinated Cp* Ligand into Coordination Chemistry.

The reaction of AgBF4 and [Rh(COD)Cl]2 (COD=1,5-cyclooctadiene) in presence of [NEt4 ][C5 (CF3 )5 ] afforded the fluorocarbon soluble complex [Rh(COD)(C5 (CF3 )5 )] by salt metathesis. This complex represents the first example for a successful coordination of the weakly basic [C5 (CF3 )5 ]- ligand, since its first synthesis in 1980. In addition to [Rh(COD)(C5 (CF3 )5 )] also the byproduct [Rh(COD)(C5 (CF3 )4 H)] was isolated and fully characterized. Accompanying DFT studies showed that the interaction energy of the [C5 (CF3 )5 ]- ligand towards the 12-electron fragment [Rh(COD)]+ is ≈70 kcal mol-1 lower in comparison to [C5 (CH3 )5 ]- due to reduced electrostatic interactions and weaker π-donor properties of the ligand. The quantitative but reversible substitution of the [C5 (CF3 )5 ]- ligand by toluene, converting it into a weakly coordinating anion, experimentally proved the extraordinary weak bonding interaction.

Die Einführung des Perfluorierten Cp*‐Liganden in die Koordinationschemie

AbstractDie Reaktion zwischen AgBF4 und [Rh(COD)Cl]2 (COD=1,5‐Cyclooctadien) in Gegenwart von [NEt4][C5(CF3)5] ergab den perfluorcarbonlöslichen Komplex [Rh(COD)(C5(CF3)5)] durch Salzmetathese. Dieser Komplex stellt das erste Beispiel für eine erfolgreiche Koordination des schwach basischen [C5(CF3)5]−‐Liganden, seit dessen Erstsynthese im Jahr 1980 dar. Zusätzlich zu [Rh(COD)(C5(CF3)5)] wurde das Nebenprodukt [Rh(COD)(C5(CF3)4H)] isoliert und vollständig charakterisiert. Begleitende DFT‐Rechnungen zeigen, dass die Interaktionsenergie des [C5(CF3)5]−‐Liganden gegenüber dem 12‐Elektronen [Rh(COD)]+‐Fragment aufgrund verringerter elektrostatischer Interaktionen und einer schwächeren π‐Donorfähigkeit um ≈70 kcal mol−1 im Vergleich zu [C5(CH3)5]− erniedrigt ist. Die quantitative, jedoch reversible Substitution des [C5(CF3)5]−‐Liganden durch Toluol, die ihn in ein schwach koordinierendes Anion überführt, demonstriert experimentell die außergewöhnlich schwache Bindungssituation.

Synthesis and structural characterizations of Pd(II) complexes bearing the new hexahydropyrimidine and tetrahydropyrimidinium based bis(pyrazole) ligands with DFT studies

The one pot reaction between 1,3­-diaminopropane, 3,5-dimethylpyrazole and paraformaldehyde afforded 1,3­-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)hexahydropyrimidine 1 in an excellent yield. The reaction of 1 with one equivalent of N-bromosuccinimide in DME gave the oxidized product 2; the same reaction in the presence of 4 equivalents of NBS yielded the pyrazole ring brominated product. Treatment of 2 with NH4PF6 gave its PF6− salt 3. Conversely, its BF4− salt was obtained directly from the reaction of AgBF4 with 1. Treatment of 3 with palladium(II) precursors gave two monomeric trans chelated complexes containing acetate and chloride ions as their PF6− salts. Conversely, 1 reacts with palladium(II) source to give the dimeric 20-membered palladacycle. The monomeric complexes are rigid molecules, whereas the dimer complex is fluxional as shown by their 1H NMR spectra. From the low temperature NMR study of the dimer complex the broad signals in the room temperature NMR spectrum are attributed to the fast interconversion between its conformers. All compounds were characterized by both spectroscopic and X-ray methods, and in some cases by CHN analysis. DFT calculations were performed to understand the formation of the chelate complex against its anticipated NHC complex containing the 6-membered ring and the binuclear complex against a monomeric complex in terms of 5- and 6-membered ring strain energies.

A photochromic AgBF4 complex with cis-1,2-dicyano-1,2-bis(2′,4′,5′-trimethyl-3′-thienyl)ethene: Synthesis, structure and photochromism

A new coordination compound was isolated by reaction of AgBF4 with cis-1,2-dicyano-1,2-bis(2′,4′,5′-trimethyl-3′-thienyl) ethene (cis-dbe) in benzene with the aim of suppressing cis-trans photo-isomerization of cis-dbe by the steric hindrance from metal coordination. The complex was revealed as a dinuclear structure by single crystal X-ray diffraction, where two Ag(I) ions are bridged by two cis-dbe molecules via their four N atoms of cyano groups. The benzene, employed as crystallized solvent in synthesis, was revealed to coordinate with metal center. The ligand presents as cis configuration and the two thiophene rings adopt anti-parallel conformation with reactive C distance of 3.46Å, which is short enough for the photo-cyclization. These structural features are favorable for the ring-closure reaction. On the other hand, BF4− is existed as counter anion sandwiched between the neighboring dinuclear complexes via extensive intramolecular hydrogen bonds and Van de Waals contacts. Also, strong π-π interactions exist in the complex. These weak interactions are theoretically disadvantageous to the photo-cyclization.As expected, the cis-trans photo-isomerization was successfully suppressed by involving of cis-dbe into coordination bonds and rational selecting of 405nm excitation light as evidenced by UV–Vis spectra and 1H NMR studies. And the reversible ring-closing and ring-opening reactions with color inter-conversion between yellow and red were not prohibited in solution, solid state and PMMA films, suggesting an indistinctive effect of metal coordination on ring closure.

Silver coordination complexes of 2-(diphenylphosphinomethyl)aminopyridine with weakly interacting counterions

A tri-functional ligand (Ph2PCH2)NH(2-C5H4N), DPAP-2, has been synthesized via the Mannich condensation reaction and its coordination behavior has been studied with various Ag(I) salts. The ligand is capable of P-coordination, P,N-chelation, and P,N-bridging to form Ag(I) complexes that range from discrete to 1-dimensional polymeric structures. In the 1:2 reaction of AgBF4 with DPAP-2, a 4-coordinate Ag(I) structure with P,N′-chelation is isolated (1). A counterion effect is observed in the equimolar reactions of AgX (2: X=BF4− and 3: X=tfa−) with DPAP-2, where the structures isolated are a dimer and a 1-dimensional polymer, respectively. When an equivalent of 5,5′-dimethyl-2,2′-dipyridyl (5,5′-dmbpy) was incorporated to the equimolar reaction of AgX and DPAP-2, three isostructural complexes resulted (4: X=BF4−, and supplementary structures S1: X=tfa−, and S2: X=OTf−). In the 2:1:2 reaction of AgX (5: X=BF4− and 6: X=tfa−) with DPAP-2 and 5,5′-dmbpy, two distinct complexes are isolated where DPAP-2 adopts a syn- and anti-arrangement, respectively.

Synthesis and Reactions of Pd II Complexes with Aryl, Aroyl, and Iminoaroyl Ligands – Insertion of CO and RNC into the Pd–Ar Bond and Intermolecular Coupling of the Ligands

The arylpalladium(II) complexes [PdIAr(bpy)] (Ar = Ph, C6H3-3,5-Me2, C6H4-4-OMe, C6H4-2-OMe, C6H4-4-C6H4-4-I, 1-naphthyl; bpy = 2,2′-bipyridine) undergo insertion of CO and CNR (R = tBu, C6H3-2,6-Me2) into the Pd–aryl bond to produce [PdI(COAr)(bpy)] and [PdI{C(=N–R)Ar}(bpy)]. The dinuclear complex [C6H3-3,5-{(OCH2CH2)2C6H4-3-PdI(bpy)}2] is synthesized by the oxidative addition reaction of 1,3-bis[(3-iodophenyl)-1,4,7-trioxaheptyl]benzene to [Pd(dba)2] (dba = dibenzylideneacetone). The addition of AgBF4 to the arylpalladium(II) complexes [PdIAr(bpy)] (Ar = C6H4-4-OMe, C6H4-2-OMe, 1-naphthyl) produces the intermolecular coupling products of the aryl ligands, Ar–Ar. The reactions of AgBF4 with the aroylpalladium(II) complexes [PdI(COAr)(bpy)] (Ar = C6H3-3,5-Me2, C6H4-2-OMe) result in decarbonylation and intermolecular coupling of the ligands to yield the diarylketones. The iminoaroylpalladium(II) complex [PdI{C(=NtBu)C6H3-3,5-Me2}(bpy)] undergoes hydrolysis of the ligand to yield tBuNHCO(C6H3-3,5-Me2). The addition of AgBF4 to the dinuclear complex [C6H3-3,5-{(OCH2CH2)2C6H4-3-PdI(bpy)}2] yields a mixture of the cyclic oligomers cyclo-[C6H3-3,5-{(OCH2CH2)2C6H4-3-}2]n (n = 1–4) by inter- and intramolecular coupling of the aryl ligands.

Structure and luminescence of discrete and polymeric Ag(I) complexes formed by the multidentate pyridylphosphine (PPh2CH2)2N(3-CH2C5H4N)

The new ligand (PPh2CH2)2N(3-CH2C5H4N), BPMP-3, has been shown to exhibit a variety of coordination modes including bridging (syn- and anti-) and chelation. The multifunctional ligand facilitates the formation of discrete, as well as polymeric, complexes with various Ag(I) salts. A discrete structure with a 4-coordinate silver is isolated from the 1:2 reaction of AgBF4 with BPMP-3 (1), while the 2:1 reactions of AgX (2: X=CF3CO2−, 3: X=BF4−, and 4: X=OTf−) with BPMP-3 result in 1-dimensional polymers with 2- to 5-coordinate silver atoms. Mixed ligand complexes (5, 6, and S1) are formed by the addition of 5,5′-dimethyl-2,2′-dipyridyl (5,5′-dmbpy). The 4:2:4 reactions of AgBF4 (5) and AgOTf (S1) with BPMP-3 and 5,5′-dmbpy results in a discrete structure with a box-like core. Demonstrative of the counterion effect, a 2:1:2 molecular structure was isolated from the 4:2:4 reaction with the tfa− derivative (6). Characterization of these coordination complexes includes multi-nuclear NMR spectroscopy, elemental analysis, single-crystal X-ray diffraction, and fluorometric studies.

Single, double, and triple silver centers bound by a tetradentate N,P ligand

The novel ligand 2-(bis(diphenylphosphinomethyl))picolylamine, BPMP-2, is synthesized via a one pot Mannich condensation reaction. The multidentate nature of BPMP-2 is manifested through the incorporation of two phosphorus and two nitrogen moieties, and is reported with various Ag(I) salts. Regardless of the Ag(I) salt used (BF4−, CF3SO3−, CF3CO2−), in the reaction of one equivalent of Ag(I) with two equivalents of BPMP-2 the coordination preference of the ligand is to chelate Ag(I) through the two phosphorus atoms and form the discrete structure, [Ag(BPMP-2)2][X] (1: X=BF4−, S1: X=tfa−, and S2: X=OTf−). In the 1:1 reaction of AgBF4 with BPMP-2, a dimer ([Ag(BPMP-2)]2[BF4]2, 2) is formed. Addition of 5,5′-dimethyl-2,2′-dipyridyl (bpy) results in more complex discrete structures, [Ag3(BPMP-2)(bpy)3][BF4]3 (3) and (Agtfa)4(BPMP-2)2(bpy)2 (4). Characterization of these coordination complexes includes multi-nuclear NMR spectroscopy, elemental analysis, single-crystal X-ray diffraction, and fluorometric studies.

Influence of a thioether function in short-bite diphosphine ligands on the nature of their silver complexes: structure of a trinuclear complex and of a coordination polymer

New cationic Ag(I) complexes were prepared by reaction of AgBF4 with two thioether-functionalized bis(diphenylphosphino)amine ligands, Ph2PN(p-ArSMe)PPh2 (L1) and Ph2PN(n-PrSMe)PPh2 (L2), and compared with those obtained from the unfunctionalized ligands Ph2PN(Ph)PPh2 (L3) and Ph2PN(n-Bu)PPh2 (L4), respectively. The complex [Ag3(μ3-Cl)2(μ2-L1-P,P)3](BF4) (1·BF4) contains a triangular array of Ag centres supported by three bridging L1 ligands and two triply-bridging chlorides. In contrast, ligand L2 led to the coordination polymer [{Ag2(μ3-L2,-P,P,S)2(MeCN)2}{Ag2(μ2-L2-P,P)2(MeCN)2}(BF4)4]n (2) in which the tethered thioether group connects intermolecularly a Ag2 unit to the diphosphine bridging the other Ag2 unit. With L3 and L4, two similar complexes were obtained, [Ag2(μ2-L3)(BF4)2] (3) and [Ag2(μ2-L4)(BF4)2] (4), respectively, with bridging diphosphine ligands and a BF4 anion completing the coordination sphere of the metal. Complexes 1·BF4·CH2Cl2, 2·THF, 3·3CH2Cl2 and 4 have been fully characterized, including by single crystal X-ray diffraction.

X-ray Crystal Structures of Silver Based Molecules Containing 5,5′-Dimethyl-2,2′-bipyridine and 2,2′-bipyridine

The reaction of AgBF4 with 5,5′-dimethy-2,2′-bipyridine and 2,2′-bipyridine yields three previously unreported compounds. The molecular structures of these compounds were obtained by single-crystal X-ray diffraction. Crystallization of 1 occurs in the centrosymmetric triclinic space group P-1 (No. 2) with a = 13.0069(6), b = 13.5903(6), c = 13.9489(6); and α = 95.677(2), β = 98.995(2), γ = 101.716(2) and Z = 6. Crystallization of 2 occurs in the centrosymmetric monoclinic space group C2/c (No. 15) with a = 23.413(3), b = 11.2116(13), c = 13.0653(13) and β = 123.074(3), and Z = 4. Crystallization of 3 occurs in the centrosymmetric triclinic space group P-1 (No. 2) with a = 12.6843(12), b = 12.8834(13), c = 12.9887(13), and α = 96.172(5), β = 95.149(5), γ = 98.051(6) and Z = 2. Details of the synthesis and the structural characterization of the title compounds are presented and discussed. The organic ligands 5,5′-dimethyl-2,2′-bipyridine and 2,2′-bipyridine, were used to synthesize three new complexes with AgBF4, whose structures are dependent on the type of solvent used in the reaction as well as solvent of crystallization.

Non-covalent interactions at bis(pyrazole)silver(i) or -gold(i) cations

The reaction of AgBF(4) with two equivalents of pzH (pyrazole) or dmpzH (3,5-dimethylpyrazole) leads to [Ag(pzH)(2)]BF(4) or [Ag(dmpzH)(2)]BF(4). The reaction of [AuCl(tht)] with an equimolar amount of dmpzH in refluxing hexane leads to [Au(dmpzH)(2)][AuCl(2)]. Similar complexes [Au(dmpzH)(2)]A (A = BF(4) or NO(3)) are obtained from [AuCl(tht)], two equivalents of dmpzH, and AgBF(4) or AgNO(3). The complexes [Ag(dmpzH)(2)]BF(4) and [Au(dmpzH)(2)]A (A = [AuCl(2)], BF(4) or NO(3)) crystallize as ionic pairs where the NH groups of the pyrazoles are involved in short cation-anion interactions. The nitrate complex crystallizes as a dimer, where both molecules are supported by pi-stacking interactions between the pyrazole rings. The crystal structure of [Ag(pzH)(2)]BF(4) reveals a three dimensional array of cations and anions. In solution, [Ag(pzH)(2)]BF(4) and [Ag(dmpzH)(2)]BF(4) undergo intermolecular processes involving pyrazole decoordination, and behave as 1/1 electrolytes; whereas dimethylpyrazole gold complexes do not display any dynamic behavior, and show cation-anion association also in solution.

X-ray Crystal Structures of Discrete and Polymeric Silver Based Molecules Containing 4,4′-Dimethyl-2,2′-Bipyridine and 2,2′-Bipyridine

The reaction of AgBF4 with 4,4′-dimethyl-2,2′-bipyridine and 2,2′-bipyridine yields three previously unreported compounds. The molecular structures of these compounds were obtained by single-crystal X-ray diffraction. Crystallization of 1 occurs in the centrosymmetric monoclinic space group C2/c (No. 15) with a = 23.407(3), b = 10.7552(13), c = 13.9332(17); and β = 111.893(2) and Z = 8. Crystallization of 2 occurs in the centrosymmetric orthorhombic space group Pbca (No. 61) with a = 11.178(3), b = 23.590(6), c = 29.339(8) and Z = 8. Crystallization of 3 occurs in the centrosymmetric monoclinic space group P21/c (No. 14) with a = 11.2250(6), b = 8.7713(5), c = 15.4048(8), and β = 109.333(2) and Z = 4. Details of the synthesis and the structural characterization of the title compounds are presented and discussed. The organic ligands 4,4′-dimethyl-2,2′-bipyridine and 2,2′-bipyridine, were used to synthesize three new complexes with AgBF4, whose structures are dependent on the type of solvent used in the reaction as well as solvent of crystallization.

Chemical Properties of Mononuclear and Dinuclear Phenylplatinum(II) Hydroxo Complexes with Cod Ligands. Transmetalation of Arylboronic Acids, Coupling of the Phenyl Ligands, and Carbonylation

The reaction of bpy with [{Pt(Ph)(cod)}2(μ-OH)](BF4) (1-BF4; cod = 1,5-cyclooctadiene) in acetone splits a Pt−O bond to yield a mixture of Pt(CH2COMe)(Ph)(cod) (2) and [Pt(Ph)(bpy)(cod)](BF4) (3-BF4), whereas a similar reaction in toluene produces 3-BF4 and Pt(OH)(Ph)(cod) (4). The complex 4 was obtained in solution and was not isolated as analytically pure crystals because of its gradual disproportionation, giving PtPh2(cod) (5). The dinuclear complex 1-BF4 reacts with ArB(OH)2 (Ar = Ph, C6H2F3-2,4,6) to form 5 and Pt(C6H2F3-2,4,6)(Ph)(cod) (6), respectively, via aryl group transfer from boron to platinum. The accompanying formation of B(OH)3 has been confirmed by 11B{1H} NMR spectroscopy. The reaction of BF3·Et2O with 1-BF4 followed by the addition of NH4Cl(aq) produces biphenyl and PtCl2(cod), which takes place possibly via a dinuclear intermediate. The cationic dinuclear complex 1-BF4 reacts with CO (1 atm) to form benzophenone. Since the reactions of AgBF4 with Pt(COPh)(I)(cod) (7) and CO with [Pt(Ph)(THF)(cod)](BF4) also yield benzophenone, the above carbonylation of 1-BF4 is considered to involve mononuclear intermediates.

Site Directed Synthesis of Mono and Disubstituted SF5‐Polyfluoroalkyl Benzenes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Coordination modes of diphosphines in silver(I)?diphosphine complexes mediated by 2,4,6-tri(2-pyridyl)-1,3,5-triazine (tptz)

Silver (I) complexes [Ag2(tptz)(dppm)2(DMF)](BF4)2·2DMF (1), [Ag(tptz)(dppe)]n(BF4)n·2nH2O·nMeOH (2), [Ag2(tptz)2(dppp)2](BF4)2(3) and [Ag2(tptz)2(dppb)](BF4)2(4) were obtained from the reactions of AgBF4 and diphosphine Ph2P(CH2) nPPh2 (Lpp, n=1–4) in the presence of 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz) in MeOH–DMF. Single crystal analyses showed that the closed metallocyclic unit [Ag2(Lpp)2]2+ with double Lpp bridges was obtained in (1) and (3) with an odd number of n, while an open metallochain (Ag2Lpp)2+ with a single bridge formed in (2) and (4) with n being even. Coordination modes for the diphosphines are directly related to the rigid tptz ligand with a large π-system.

Disproportionation of PtPh(CH2COMe)(cod) and Conproportionation of PtPh2(cod) and Pt(CH2COMe)2(cod) via Intermolecular Phenyl Ligand Transfer

PtI(Ph)(cod) (cod = 1,5-cyclooctadiene)reacts with acetone in the presence of Ag2O to give a mixture of Pt(CH2COMe)(Ph)(cod) (1), PtPh2(cod) (2), and Pt(CH2COMe)2(cod) (3) in a molar ratio of 61:20:19. Complex 1, having the phenyl and acetonyl ligands, was isolated by recrystallization of the products and characterized by X-ray crystallography. The reaction of AgBF4 with PtI(Ph)(cod) forms [PtPh(cod)(acetone-d6)]BF4 and does not give a diarylplatinum complex. Thus, Ag2O, in the reaction of PtI(Ph)(cod) with acetone, promotes activation of both the Pt−I bond of PtI(Ph)(cod) and a C−H bond of acetone. Heating of 1 in acetone at 50 °C causes its partial disproportionation into 2 and 3 to give a mixture of the above three complexes. An equimolar mixture of 2 and 3 in acetone undergoes conproportionation into 1 at 50 °C to give a mixture of the complexes. The conproportionation is completed in 30 h to form the mixture with [1]:[2]:[3] = 66:17:17, while the above disproportionation of 1 does not attain equilibr...

Chemical Properties of Cationic Phenylplatinum(II) Complexes with a 2,2‘-Bipyridine Ligand. Insertion of CO and Allene into the Pt−C Bond and Oxidative Addition of MeI

[PtPh(bpy)(solvent)]BF4 (1-MeCN, solvent = MeCN; 1-acetone, solvent = acetone) are prepared from the reaction of HBF4 with PtPh2(bpy) or from the reaction of AgBF4 with PtI(Ph)(bpy). The MeCN ligand of 1-MeCN in a CD3CN solution undergoes exchange with the solvent in 12 h at room temperature. The coordinated solvent of 1-acetone is replaced with acetone-d6 much more rapidly. 1-acetone reacts easily with H2O and CO to form 1-OH2 and 1-CO, respectively. The reaction of phenylallene with 1-acetone produces the (π-allyl)platinum complex [Pt(η3-CH2CPhCHPh)(bpy)]BF4 (2) as a mixture of syn and anti isomers. One of the isomers, 2-syn, was isolated by recrystallization of the products and characterized by X-ray crystallography and 1H NMR spectroscopy. The complex reacts with CO (1 atm) at room temperature to form a mixture of [Pt((Z)-CH2CPhCHPh)(bpy)(CO)]BF4 (3-Z) and [Pt((E)-CH2CPhCHPh)(bpy)(CO)]BF4 (3-E). The ratio of 3-Z to 3-E decreases gradually during the reaction to afford an equilibrium mixture ([3-Z]:[3-E] = 35:65) after 26 min. First-order rate constants of the reaction under CO and under argon are similar to each other, indicating that the isomerization occurs via a pentacoordinate intermediate with carbonyl and π-allyl ligands bonded to the Pt center. 1-MeCN reacts with MeI at 50 °C to produce a mixture of two isomeric cationic Pt(IV) complexes after 9 days. X-ray crystallography of one of the products, [PtI(Me)(Ph)(NCMe)(bpy)]BF4 (4), revealed an octahedral structure having the methyl, iodo, and bipyridine ligands in the same coordination plane.

Diphosphine mediated assembly of multinuclear silver complexes containing the thiolato ligand 2-mercaptobenzoxazole (Hmbo)

A new complex [Ag4(μ2-S-mbo)4(dppp)4](1) is obtained from the reaction of AgBF4 and Hmbo(2-mercaptobenzoxazole) with the participation of dppp(bis(diphenylphosphino) propane). Single crystal X-ray diffraction analysis shows that it is discrete neutral molecule and composed of two asymmetrical moieties. Four Ag atoms in each molecule are completely coplanar and of similar environment. The ligands Hmbo and dppp in complex 1 bridge two Ag atoms through “μ2-S-mbo” and P atoms in two ends, respectively. The possible mechanism of the reaction is provided, and the sequence of adding materials and the length of backbone (CH2)n in diphosphine play an important role in the results of the reactions.

Calix[4]arene-derived diphosphines, diphosphinites and diphosphites as chelating ligands for transition metal ions. Encapsulation of silver(I) in a calix-crown diphosphite

A series of lower rim-functionalised calix[4]arenes bearing 1,3-positioned phosphorus(III) ligands L1111–L999 have been synthesized and their coordinative properties examined. L1111 and L222 {5,11,17,23-tetra-tert-butyl-25,27-bis[2-(diphenylphosphino)ethoxy]- and -25,27-bis(diphenylphosphinomethoxy)-26,28-bis(3-oxabutyloxy)calix[4]arene} react with [Rh(nbd)(THF)2]BF4 (nbd = 1,5-norbornadiene; THF = tetrahydrofuran) to afford in high yield the complexes [Rh(nbd)L1111]BF4 and [Rh(nbd)L222]BF4, respectively, where the calixarene behaves as a P,P′ chelator. Both complexes catalyse hydroformylation of styrene at comparable rates, the linear∶branched aldehyde ratio being 5∶95. The presence of the ether side groups did not exert a noticeable effect on the selectivity nor the catalytic activity. Reaction of L1111–L888 with [Pd(η3-C3H4Me)(THF)2]BF4 gave the corresponding cationic chelate complexes [Pd(η3-C3H4Me)Liii]BF4 that are active in the catalytic alkylation of 1,3-diphenylprop-2-enyl acetate with dimethyl malonate. Owing to the presence of a non-planar Pd–allyl fragment, the achiral calixarene subunits of some of these complexes are no longer C2v-symmetrical, as evidenced by the 1H and 13C NMR spectra that show non-equivalent side groups. Selective chelation via the two phosphorus atoms was also observed in the complexes [RuCl(p-MeC6H4Pri)Liii]BF4 (Liii = L333 or L444) obtained by reaction of the amide phosphines Liii with [RuCl(p-MeC6H4Pri)(THF)2]BF4 [L333 = 5,11,17,23-tetra-tert-butyl-25,27-bis(diethylcarbamoylmethoxy)-26,28-bis(diphenylphosphinomethoxy)- and L444 = 5,11,17,23-tetra-tert-butyl-25,27-bis(diphenylphosphinomethoxy)-26,28-bis{(1-(R)-phenylethyl)carbamoylmethoxy}-calix[4]arene]. Reaction of L333 or L444 with neutral [RuCl2(p-MeC6H4Pri)]2 afforded the bimetallic complexes [{RuCl(p-MeC6H4Pri)}2Liii] where the calixarene acts as a P,P′ bridging ligand. Reaction of AgBF4 with calix-crown L999 {25,27-bis(diethoxyphosphinoxy)-26,28-(3,6,9-trioxaundecane-1,11-dioxy)calix[4]arene} resulted in quantitative formation of the complex [AgL999]BF4 in which the silver(I) ion lies inside the cavity constituted by the crown ether fragment and the two phosphorus arms. As revealed by a single crystal X-ray diffraction study, the Ag+ ion has a trigonal P2O coordination environment with a P–Ag–P angle of 134.74(4)°.