Phenylethynyl Ligands Research Articles

Redox‐Neutral Syntheses and Electrochemical Studies of 10‐Bromo‐Substituted Light‐Stable Antivitamin B12 Candidates

AbstractThis publication describes the straightforward and redox‐neutral synthesis of 10‐bromophenylethynylcobalamin and its facile conversion to 10‐bromoaquacobalamin. In this approach, the phenylethynyl ligand acts as convenient light‐stable protecting group that is removed in quantitative yield under acidic conditions. The proteolytic cleavage at pH 2.0 was studied under pseudo‐first‐order conditions and is 1.5 times slower than that of phenylethynylcobalamin with a hydrogen instead of a bromine at C(10). Preliminary electrochemical studies of organometallic ethynyl‐Cbls (Cbl=cobalamin) are reported for the first time. A reduction potential of −0.94 V vs. Ag/AgCl was determined for the CoIII/CoI reduction of 10‐bromophenylethynylcobalamin. The positive potential shift of 180 mV compared to phenylethynylcobalamin is in agreement with earlier electrochemical studies of related cyanocobalamins.

Bidentate Phosphine-Assisted Synthesis of an All-Alkynyl-Protected Ag74 Nanocluster.

Determining the total structure of metal nanoparticles is vital to understand their properties. In this work, the first all-alkynyl-protected Ag nanocluster, Ag74(C≡CPh)44, was synthesized and structurally characterized by single crystal diffraction. Ag atoms are arranged in a Ag4@Ag22@Ag48 three shell structure and all 44 phenylethynyl ligands coordinated with Ag in a μ3 mode. In spite of being absent in nanocluster, 31P NMR study reveals that bidentate phosphine first reacts with Ag(I) to form a dinuclear complex, from which Ag atoms are then released to phenylethynyl ligands. This phosphine mediated strategy may find general application in synthesis of alkynyl-protected Ag nanoclusters.

Conjugated, trans‐Spanning Ligands as Models for Multivalent p‐Phenyleneethynylenes

AbstractA conjugated, pyridine‐containing, phenylethynyl ligand that forms complexes with AgI and PdII has been developed. NMR titration studies with PdII reveal a stoichiometric binding of the ligand to the metal atom, while similar studies with AgI reveal a binding that is dynamic on the NMR timescale. Analysis of the NMR spectroscopic data by Job's plot analysis and non‐linear curve fitting of a titration curve reveals a 1:1 binding ratio of ligand/silver cation and an association constant of Ka = 53 M–1. X‐ray crystal structures of the ligand–metal complexes suggest ample room for the nearly barrierless rotation of the unsubstituted central benzene ring of the para‐phenylethynyl chain. Subtle electronic differences in substituted systems provide some evidence of impaired rotation.

Cyclopentadienyl chromium and tungsten complexes with halide, methyl and σ-phenylethynyl ligands: Structures of (η 5-C 5H 5)Cr(NO) 2(–C [tbnd]C–C 6H 5), (η 5-C 5H 5)Cr(NO) 2I and [(η 5-C 5H 4)-COOCH 3]W(CO) 3Cl

With copper(I) iodide as catalyst, σ-alkynyls, compounds (η 5-C 5H 5)Cr(NO) 2(C C–C 6H 5) ( 5), [(η 5-C 5H 4)-COOCH 3]Cr(NO) 2(C C–C 6H 5) ( 10), and [(η 5-C 5H 4)-COOCH 3]W(CO) 3(C C–C 6H 5) ( 13), were prepared from their corresponding metal chloride 1, 6 and 12. Structures of compound 3, 5 and 12 have been solved by X-ray diffraction studies. In the case of 5, there is an internal mirror plane passing through the phenylethynyl ligand and bisecting the Cp ring. The phenyl group is oriented perpendicularly to the Cp with an eclipsed conformation. The twist angle is 0° and 118.4° for –C C–Ph and two NO ligands, respectively. The orientation is rationalized in terms of orbital overlap between ψ 3 of Cp, dπ of Cr atom, and π ∗ of alkynyl ligand, and complemented by molecular orbital calculation. The opposite correlation was observed on the chemical shift assignments of C(2)–C(5) on Cp ring in compounds 6 and 12, using HetCOR NMR spectroscopy. The electron density distribution in the cyclopentadienyl ring is discussed on the basis of 13C NMR data and compared with the calculations via density functional B3LYP correlation-exchange method.

An unusual Cu 2Ru 2 cluster containing a tetrameric phenylethynyl ligand

The reaction between RuCl(PPh 3) 2Cp ∗ and {Cu(CCPh)} n in refluxing benzene afforded Ru 2Cu 2(C 2Ph) 5H 2(Cl)(PPh 3)Cp ∗ 2, which contains an unusual tetramer of the phenylethynyl group which interacts with an Ru…Cu…Cu…Ru chain. The second Ru atom is part of a ruthenocenyl moiety which interacts weakly with the second Cu atom, and bears a vinylidene which bridges an Ru–Cu vector. The structure of a second modification of Ru(C CPh)(CO)(PPh 3)Cp ∗ is also reported.

Synthese und Reaktionsverhalten von Platin(II) und Kupfer(I) Koordinationspolymeren; die Festkörperstruktur von { trans-(Ph 3P) 2Pt[(η 2-CCPh)CuBr] 2} n und trans-(Ph 3P) 2Pt[(η 2-CCPh)CuNO 3] 2

The title complex { trans-(Ph 3P) 2Pt[(η 2-CCPh)CuX] 2} n ( 3a, X=Cl; 3b, X=Br) can be prepared by treatment of trans-(Ph 3P) 2Pt(CCPh) 2 ( 1) with two equivalents of [CuX] ( 2a, X=Cl; 2b, X=Br) in quantitative yield. The reaction chemistry of 3b towards organic chelating molecules is reported. Treatment of 3b with, for example, 2,2 ′-bipy ( 4) produces the chelated copper(I) species [(bipy)CuBr] 2 ( 6) along with 1. However, if 3b is reacted with the silver(I) salt [AgNO 3] ( 5a) then trimetallic trans-(Ph 3P) 2Pt [(η 2-CCPh)CuNO 3] 2 ( 7) is formed in which each phenylethynyl ligand is η 2-coordinated to a copper(I) nitrate unit. This complex is also obtained, when 1 is reacted with two equivalents of [Cu(NCMe) 4]NO 3 ( 5b). The solid-state structures of 3b and 7 are reported. Polymeric 3b crystallises in the triclinic space group P 1 ̄ with cell parameters a=11.5958(3) Å, b=13.3491(3) Å, c=15.4875(4) Å, α=81.755(1)°, β=87.324(1)°, γ=85.472(1)°, V=2363.66(10) Å 3, Z=2 and ρ=1.818 g mol −1. Complex 7: monoclinic space group P2 / n with a=9.8971(1), b=14.2324(3), c=16.6957(2) Å, β=105.478(1)°, V=2266.46(6) Å 3, Z=2 and ρ=1.719 g mol −1. In 3b a linear polymeric structure is adopted. 3 contains two crystallographic independent trans-Pt(CCPh) 2 units which are linked by 4-membered Cu 2(μ-Br) 2 cycles at which the respective PhCC units are η 2-coordinated to the copper(I) ions. In 7 each of the two PhCC entities is π-bound to a mononuclear CuNO 3 moiety of which the NO 3 ligand is chelate-bound to copper(I).

Organoaluminates with Three Terminal Phenylethynyl Groups and Their Interactions with Alkali Metal Cations

The synthesis of [K+·THF(2,6-iPr2C6H3N(SiMe3)Al(C⋮CPh)3)-]2 (1), [Na+·THF (2,6-iPr2C6H3N(SiMe3)Al(C⋮CPh)3)-]2 (2), and [Li+·dioxane (2,6-iPr2C6H3N(SiMe3)Al(C⋮CPh)3)-]2·2dioxane (3) respectively by the reaction of [2,6-iPr2C6H3N(SiMe3)AlCl2]2 (4) with the corresponding phenylethynyl alkali metal salt is reported. In compound 1 the potassium (2, sodium) interacts with the C⋮C bonds of four phenylethynyl groups. A further coordination site of the potassium (sodium) is occupied by a THF molecule. Thus, the cation therein acts as a bridging moiety to form the dimer. In compound 3 each of the lithium cations is 2-fold coordinated by phenylethynyl ligands and two dioxane molecules. One of the dioxane molecules in 3 functions as a bridge forming the dimer. The herein described compounds are the first structurally characterized species having three terminal phenylethynyl groups bound to the aluminum atom.

Reaction of alkynylsilanes with CuCl in polar solvents leading to alkynyl group transfer from Si to Cu

The reaction of 1-phenyl-2-trimethylsilylethyne with CuCl at 80–100°C in N, N-dimethylformamide (DMF) or N, N-dimethylimidazolidinone (DMI) yielded the alkynylcopper species [Cu 2Cl(CCPh)] n ( 1) in 56–63% yields. Heating 1 at 80°C under aerobic conditions gave 1,4-diphenyl-1,3-butadiyne in 82% yield via an oxidative coupling of the phenylethynyl ligands.

π-Allyliridium(I) complexes, Ir(η3-CH2CHCHAr)(CO)(PPh3)2 (Ar=Ph, C6H4Me-p, C6H4Br-p). Comparison of their structures and chemical properties with analogous Rh complexes

Arylallenes such as (4-methylphenyl)allene, phenylallene, and (4-bromophenyl)allene react with IrH(CO)(PPh3)3 to give the π-allyliridium(I) complexes, Ir(η3-CH2CHCHAr)(CO)(PPh3)2 (Ar=C6H4Me-p, Ph, and C6H4Br-p). Crystallographic studies of the complexes showed a similar coordination geometry to that of Rh(η3-CH2CHCHX)(CO)(PPh3)2. An equimolar reaction of phenylacetylene with Ir(η3-CH2CHCHC6H4Me-p)(CO)(PPh3)2 gives a mixture of trans-Ir(CCPh)(CO)(PPh3)2 and trans,trans-IrH(CCPh)2(CO)(PPh3)2 accompanied by the liberation of 1-(4-methylphenyl)-1-propene. The Ir(III) acetylide complex is obtained separately from the reaction of excess phenylacetylene with the π-allyliridium(I) complex. The respective square-planar and octahedral structures of these complexes are determined by X-ray and NMR analyses. The NMR spectra of the reaction mixture indicate concurrent formation of the Ir(I) and Ir(III) complexes having the phenylethynyl ligands.

Probing diruthenium σ-alkynyl bonding interactions via substituent effects. Linear free energy relationships in dinuclear compounds VI

Several paramagnetic tetrakis(diarylformamidinato)diruthenium(II,III) complexes bearing one phenylethynyl ligand at the axial position, Ru 2(ArNC(H)NAr) 4(CCPh) (Ar as p-ClC 6H 4 ( 2), m-ClC 6H 4 ( 3), m-CF 3C 6H 4 ( 4), 3,4-Cl 2C 6H 3 ( 5), and 3,5-Cl 2C 6H 3 ( 6)), were prepared and characterized. Cyclic voltammetry studies of 2– 6 revealed the presence of two one-electron redox couples: Ru 2 6+/Ru 2 5+ and Ru 2 5+/Ru 2 4+, and the half-wave potential for the latter correlates linearly with the Hammett constant ( σ) of the aryl substituent. Molecular structures of 3 and 6 were determined by X-ray crystallography. The nature of Ru 2–CC bonding interaction was predominantly Ru–C α σ-bonding based on the substituent-dependence of υ(CC), which decreases linearly with the increase of the Hammett constant σ of substituent.

Anti,mer-[Bis(2-diphenylphosphinoethyl)(n-propyl)amine-N,P,P'](phenylethynyl)[(Z)-1-p-tolyl-4-phenyl-η3-but-1-en-3-ynyl]ruthenium(II) Chloroform Solvate

The title structure, [Ru(C 8 H 5 )(C 17 H 13 )(C 31 H 35 NP 2 )].CHCl 3 , consists of discrete anti,mer-[Ru(C≡CPh){η 3 -PhC≡C-C=CH(p-tolyl)}(PNP)] neutral molecules, where PNP is CH 3 CH 2 CH 2 N(CH 2 CH 2 PPh 2 ) 2 , and CHCl 3 solvate molecules. The Ru II metal centre is pseudo-octahedrally coordinated by a meridional tridentate PNP ligand, a phenylethynyl ligand and a η 3 -bonded (Z)-1-p-tolyl-4-phenyl-η 3 -but-1-en-3-ynyl ligand. The butenynyl moiety is anti with respect to the n-propyl tail on the N-atom donor of the aminodiphosphine ligand and lies in a plane almost perpendicular to that containing the Ru(PNP) moiety.

Synthesis and characterisation of monomeric, dimeric and polymeric ferrocenylacetylides. Crystal structure of 1,1′-bis(phenylethynyl)ferrocene

The reactions of alkynyltrimethylstannanes with 1,1′-dilithioferrocene have given several ferrocenylacetylides, namely 1-pheny]-ethynyl-1′-iodo-ferrocene ( 1), 1,1′-bis(phenylethynyl)ferrocene ( 2), 1,4-di(1′-iodoferrocenylethynyl)benzene ( 3) and poly[1,4-(1′-ferrocenylethynyl)ethynylbenzene] ( 4). The versatility of this reaction for the formation of ferrocenylacetylides is demonstrated. The crystal structure of 2 has been determined, and shown to involve a linear array of the groups with a cis arrangement of the phenylethynyl ligands.

X-ray structure and bonding of 1-phenylethynyl-2-phenyl-1,2-dicarbadodecaborane(12), [1-(PhCC)-2-Ph-1,2-C 2B 10H 10], a model alkyne complex containing a rich variety of carbon-carbon bond types

The crystal and molecular structure of 1-phenylethynyl-2-phenyl-1,2-dicarbadodecaborane(12) ( 1), prepared by the reaction between 1,4-diphenylbutadi-yne and the decaborane adduct B 10H 12(NCMe) 2 in boiling toluene, have been established by an X-ray crystallographic study. Evidence of some delocalization of pi-electronic charge in the phenylethynyl ligand towards the carborane cage is provided by the carboncarbon bond distances [1.431(2), 1.194(2) and 1.433(2) Å, respectively from benzene ring to carborane isocahedron] and Molecular Orbital Bond Index (MOBI) calculations, which also reveal subtle differences in the bonding of the two skeletal carbon atoms to their boron neighbours in the icosahedron. Consideration of ( 1) as an adduct in which one alkyne function of PhCCCCPh coordinates to an arachno-shaped B 10H 10 residue reveals the strong electron-withdrawing capacity of the latter, which is compared with other borane and metal cluster residues.

Bis(phenylethynyl)hafnocene as an Organometallic Chelate Ligand

Abstract The application of (η5-C5H4SiMe3)2Hf(C≡CPh)2 (1) as an organometallic chelate ligand towards different organometallic building blocks will be discussed. 1 reacts with Ni(CO)4 (2) or Co2(CO)8 (4) to yield {(η5-C5H4SiMe3)2Hf(C≡CPh)2}M(CO) (M = Ni: 3, M = Co: 5) and (η5-C5H4SiMe3)2Hf(C≡CPh) [μ-(η2-C≡CPh)Co2(CO)6] (6). In 6 one of the two phenylethynyl units is η2-side-on coordinated to Co2(CO)6 forming a 1,2-dicobaltatetrahedrane unit. However, the reaction of 1 with Fe2(CO)9 (7) affords (η5-C5H4SiMe3)2Hf[(η2-C≡CPh)Fe(CO)4]2 (8), a compound, in which both of the phenylethynyl ligands are η2-side-on coordinated to Fe(CO)4 complex fragments. All new synthesized compounds have been characterized by analytical and spectroscopic data. Additionally, the structure of 3 was established by X-ray diffraction study.

Crystal structure of a pentanuclear gold-silver cluster complex

The title compound, [C16H36N]+[C48H30Au3Ag2]−, crystallizes in the triclinic space groupP1−1, witha=18.199(12),b=19.210(8),c=19.270(9)A,α=71.34(3)°β=76.43(4)° γ=72.95(5)° andZ=4, with two independent molecules in the asymmetric unit. The structure was solved by direct methods and refined by full-matrix least squares methods toR=0.072 for 3739 observed reflections. The metal atoms have a trigonal-bipyramidal arrangement with the three Au atoms forming an equilateral triangle and two Ag atoms occupying apical positions. Each Au atom is σ-bonded to phenylethynyl ligands in a linear coordination. Each Ag atom is asymmetrically pi-bonded to three alkyne groups. The Au-Au distances lie in the range of 3.934–4.010 A, indicating the lack of Au-Au bond.

Carbon-carbon bond formation by coupling of two phenylethynyl ligands in an organolanthanide system

[(C 5 Me 5 ) 2 Sm] 2 (μ-η 2 :η 2 -PhC 4 Ph) is formed from the reaction of [(C 5 Me 5 ) 2 Sm(μ-H)] 2 with PhC≡CH, from the thermolysis of (C 5 Me 5 ) 2 Sm(C≡CPh)(THF) at 80-145°C, from the reaction of (C 5 Me 5 ) 2 Sm with PhC≡CH, and from the reaction of (C 5 Me 5 ) 2 Sm[CH(SiMe 3 ) 2 ] with PhC≡CH, a reaction that has been reported to form [(C 5 Me 5 ) 2 Sm(μ-C≡CPh)] 2

Zum Koordinationsverhalten von Tris-phenylethinyl-phosphan; synthese und charakterisierung von (H 5C 6C≡C) 2P[(η 2-C≡CC 6H 5)Co 2(CO) 5] 2

The reaction of P(C≡CC 6H 5) 3 (I) with Co 2(CO) 8 (II) yields H 5C 6C≡C) 2P[(η 2-C≡CC 6H 5)Co 2(CO) 5] 2 (III) a compound containing a six-membered C 2P 2Co 2 ring. One of the three alkyne units of I in II is coordinated side-on to the two cobalt atoms of one of the Co 2(CO) 5 fragments and the free electron pair of the phosphorus atom of the same ligand is coordinated to a cobalt atom of the second Co 2(CO) 5 unit. The total of four non-coordinated phenylethynyl ligands make III an attractive molecule for further investigation.

Preparation, identification, and X-ray structure of a novel high-nuclearity heterometallic anionic Ag6Cu7 cluster

A novel silver–copper anionic cluster [Ag6Cu7(C2Ph)14]– has been synthesized from the reaction of [PhC2AgC2Ph]– and a mixture of [AgC2Ph]n and [CuC2Ph]n; its structure constitutes a central linearly co-ordinated copper atom linked through Cu–Ag interactions to three tetranuclear [Ag2Cu2(C2Ph)4] subclusters, and within each unit of the sub-cluster, copper and silver atoms are bonded through metal–metal interactions and via bridged phenylethynyl ligands.

Über Metallalkyl‐ und ‐aryl‐ Verbindungen, XXVII. Darstellung und Kristallstruktur von Bis(phenylethinyl)bis‐(N,N,N′,N′‐tetramethylethylendiamin)magnesium, Mg(CCPh)2(tmeda)2

Metal Alkyl and Aryl Compounds, XXVII. Preparation and Crystal structure of Bis(phenylethynyl)bis(N, N, N′,N′‐tetramethylethylenediamine)magnesium, Mg(CCPh)2(tmeda)2The title compound has been prepared from bis(phenylethynyl)magnesium and N, N, N′,N′‐tetramethylethylenediamine (tmeda) and investigated by X‐ray diffraction methods (orthorhombic space group Cmcm, Z = 4, 696 (reflections, R = 0.049). It represents a first example of an organomagnesium compound with octahedral coordination of the central atom. The phenylethynyl ligands are in trans position.