Syntheses and molecular structures of some phosphine-gold(I) derivatives of 1,3-diynes

The syntheses of several diynylgold(I) phosphine complexes, including Au(CCCCH){P(tol)₃} (1), Au(CCCCSiMe₃)(PR₃) (R = Ph 2-Ph, tol 2-tol), Au(CCCCFc)(PPh₃) (3), {(tol)₃P}Au(CC)_nAu{P(tol)₃} [n = 2 (4), 3 (6), 4 (7)], {(Ph₃P)Au}CCCC{Au[P(tol)₃]} (5), [ppn][Au{CCCCAu[P(tol)₃]}₂] (8), [Au₂(μ-I)(μ-dppm)₂][Au(CCCCSiMe₃)₂] (9), Hg{CCCCAu(PR₃)}₂ (R = Ph 10-Ph, tol 10-tol) and {(triphos)Cu}CCCC{Au[P(tol)₃]} (11) are described. Of these, the X-ray molecular structures of 1, 2-tol, 3, 4 and 9 have been determined.     

Further chemistry of ruthenium butatrienylidene complexes

Several complexes have been obtained from reactions carried out in early attempts to prepare the diynyl complexes Ru(CCCCR)(dppe)Cp* (R = H, SiMe₃). These have been identified crystallographically as the acyl complex Ru{CCC(O)Me}(dppe)Cp* (3), the cationic imido complex [Ru{CCC(NH₂)Me}(dppe)Cp*]PF₆ (4), the binuclear butenynylallenylidene [{Ru(dppe)Cp*}₂{μ-CCC(OMe)CHCMeCC}]PF₆ (5), and the bis(ethynyl)cyclobutenylidene [{Ru(dppe)Cp*}₂{μ-CCC₄H₂(SiMe₃)CC}]PF₆ (6). NMR studies of 5 have revealed the existence of two isomers. Plausible routes for their formation from the putative butatrienylidene intermediate [Ru(CCCCH₂)(dppe)Cp*]⁺ (A) are discussed.     

Some complexes containing carbon chains end-capped with tungsten or ruthenium groups and tricobalt carbonyl clusters

The Pd(0)/Cu(I)-catalysed reactions between Co₃(μ₃-CBr) (CO)₉ and W(CCCCH)(CO)₃Cp gives the C₅ complex {Cp(OC)₃W}CCCCC{Co₃(CO)₉} (2). Similarly, Co₃(μ₃-CBr)(μ-dppm)(CO)₇ and W(CCCCH)(CO)₃Cp or Ru(CCCCH)(dppe)Cp* give {Cp(OC)₃W}CCCCC{Co₃(μ-dppm)(CO)₇} and {Cp*(dppe)Ru}CCCCC{Co₃(μ-dppmn)(CO)₇} (5). An attempt to prepare a C₃ analogue from Ru(CCH)(PPh₃)₂Cp and Co₃(μ₃-CBr)(CO)₉ gave instead the acyl derivative {Cp(Ph₃P)₂Ru}CCC(O)C{Co₃(CO)₈(PPh₃)} (7). The X-ray structures of 2, 5 and 7 are reported: the C₅ chains in 2 and 5 have an essentially unperturbed -CC-CC-C formulation.     

Iodo-alkynyl- and iodo-butadiynyl-ruthenium complexes

Addition of [I(py)₂]BF₄ to Ru(CCH)(dppe)Cp∗ gave the iodovinylidene [Ru(CCHI)(dppe)Cp∗]BF₄1, which could be deprotonated to Ru(CCI)(dppe)Cp∗ 2. The attempted preparation of Ru(CCCCI)(dppe)Cp∗, followed by derivatisation with tcne, gave the dienynyl Ru{CCC[C(CN)₂]CIC(CN)₂}(dppe)Cp∗ 3. The Pd(0)/Cu(I)-catalysed reaction of 3 with Ru{CCCCAu(PPh₃)}(dppe)Cp∗ afforded Ru{CCCC(CN)₂CC(CN)₂Au(PPh₃)}(dppe)Cp∗ 4 by formal replacement of I⁺ by [Au(PPh₃)]⁺. XRD structures of 1-4 are reported.     

Solvent and phosphine dependency in the reaction of cis-RuCl2(P-P)2 (P-P = dppm or dppe) with terminal alkynes

Reaction of cis-[RuCl₂(dppm)₂] (dppm = 1,2-bis(diphenylphosphino)methane) with PhCCH and NaPF₆ utilising methanol as solvent results in the formation of the η³-butenynyl complex [Ru(η³-PhCCCCHPh)(dppm)₂][PF₆] in good yield. Similar reactions with Bu^tCCH and PrⁿCCH resulted in the corresponding alkyl-substituted complexes and all three of these compounds have been characterised by NMR spectroscopy and X-ray crystallography. The mechanism of this reaction has been probed by employing labelling experiments with both PhCCD and PhC¹³CH allowing the identity of possible intermediates in the reaction to be determined. Furthermore, [Ru(η³-PhCCCCHPh)(dppm)₂][PF₆] has been shown to be an effective regio- and stereo-selective catalyst for the dimerisation of PhCCH to Z-PhCCCHCHPh in the absence of solvent. In contrast, no evidence for the formation of alkyne coupling was obtained from the reaction of cis-[RuCl₂(dppe)₂] (dppe = 1,2-bis(diphenylphosphino)ethane) with PhCCH and NaPF₆.     

Polymetallation of alkenes: Formation of some complexes containing branched chain carbon-rich ligands

Reactions of {(Ph₃P)AuCC}₂CC{CCAu(PPh₃)}₂ (1b), with Co₃(μ-CBr)(μ-dppm)_n(CO)_9−2n (n = 0, 1) result in complete or partial elimination of AuBr(PPh₃) to give the complexes {(OC)₉Co₃-μ₃-CCC}₂CC{CC-μ₃-CCo₃(CO)₉}₂ (3), trans-{(OC)₇(μ-dppm)Co₃-μ₃-CCC}(HCC)CC{CCAu(PPh₃)}{CC-μ₃-CCo₃(μ-dppm)(CO)₇} (4), {(OC)₇(μ-dppm)Co₃-μ₃-CCC}₂CC(CCH){CC-μ₃-CCo₃(μ-dppm)(CO)₇} (5) and {(OC)₇(μ-dppm)Co₃-μ₃-CCC}₂CC{CCAu(PPh₃)}{CC-μ₃-CCo₃(μ-dppm)(CO)₇} (6), which have been identified by spectroscopic methods and in the cases of 3, 4 and 5, by single-crystal X-ray diffraction methods.     

Formation of a cyclobutenylidene by cyclo-addition of an alkynyl-ruthenium complex to a cyano(alkynyl)ethene

In contrast to the usual formal [2+2]-cycloaddition reaction, (NC)₂CC{CC(SiPrⁱ₃)}₂, containing bulky alkynyl substituents, reacts with Ru(CCPh)(PPh₃)₂Cp to give the unprecedented cyclobutenylidene complex Ru{C(CN)₂C[CC(SiPrⁱ₃)]CC(SiPrⁱ₃)CPhC}(PPh₃)Cp, formed by addition of one of the CC(SiPrⁱ₃) groups to the Ru-CCPh moiety and subsequent electronic reorganisation.     

Synthesis and characterization of phenylacetylene-terminated poly(silyleneethynylene-4,4′-phenylethereneethynylene)s

Two kinds of phenylacetylene-terminated poly(silyleneethynylene-4,4′-phenylethereneethynylene)s, {C₆H₅CC[Si(R)₂CCC₆H₄OC₆H₄CC]_nC₆H₅} wherein R represents methyl or phenyl, were synthesized by condensation reaction between dichlorosilanes and 4,4′-diethynyldiphenyl ether using organomagnesium reagents. The polymers were characterized by NMR, IR, gel permeation chromatography, thermogravimetric analysis, and differential scattering calorimetry.     

Distinction of Push,pull effect and steric hindrance in disubstituted alkynes

The push,pull effect in two series of disubstituted alkynes was studied at the DFT level [B3LYP/6-311G(d)] by application of the ¹³C chemical shift differences (GIAO) between the alkyne carbon atoms (Δδ_CC), the charge difference between these carbons (Δq_CC), the occupation quotient (NBO) of anti-bonding π^∗, and bonding π orbitals (π^∗_CC/π_CC) and the bond length (d_CC) of the CC triple bond. The linear dependence of d_CC versus π^∗_CC/π_CC quantifies changes in the push,pull effect while deviations from the latter correlation indicate and ascertain quantitatively to what extent steric hindrance restricts the strain-less conjugation of the CC triple bond π-orbitals in the disubstituted alkynes.     

Luminescent rhenium(I)-gold(I) hetero organometallics linked by ethynylphenanthrolines

The first luminescent rhenium(I)-gold(I) hetero organometallics, Re{phenAu(PPh₃)}(CO)₃Cl (3) and Re{(PPh₃)AuphenAu(PPh₃)}(CO)₃Cl (4), have been prepared using the gold(I) complex AuCl(PPh₃) (PPh₃ = triphenylphosphine) and the novel rhenium(I) complexes Re(phenH)(CO)₃Cl (5) (phenH = 3-ethynyl-1,10-phenanthroline) or Re(HphenH)(CO)₃Cl (6) (HphenH = 3,8-bis(ethynyl)-1,10-phenanthroline). All the present rhenium(I) complexes 3-6 were revealed to possess a facial configuration (fac-isomer) with respect to the three carbonyl ligands. The main frameworks for these new gold(I) organometallics were constructed by the Au-C σ-bonding (with the η¹-type coordination) between the ethynylphenanthrolines and the Au(I) phosphine unit. Re(I)-Au(I) heterometallics 3 and 4 have shown single phosphorescence from the ³MLCT excited state and this observation can be interpreted in terms of the efficient intramolecular energy transfer from the Au(I) unit to the Re(I) unit.     

Organometallic chemistry and catalysis on gold metal surfaces

As in transition metal complexes, CN-R ligands adsorbed on powdered gold undergo attack by amines to give putative diaminocarbene groups on the gold surface. This reaction forms the basis for the discovery of a gold metal-catalyzed reaction of CN-R, primary amines (R′NH₂) and O₂ to give carbodiimides (R′-NCN-R). An analogous reaction of CO, RNH₂, and O₂ gives isocyanates (R-NCO), which react with additional amine to give urea (RNH)₂CO products. The gold-catalyzed reaction of CN-R with secondary amines (HNR′₂) and O₂ gives mixed ureas RNH(CO)NR′₂. In another type of gold-catalyzed reaction, secondary amines HN(CH₂R)₂ react with O₂ to undergo dehydrogenation to the imine product, RCHN(CH₂R). Of special interest is the high catalytic activity of gold powder, which is otherwise well-known for its poor catalytic properties.     

Some ruthenium complexes of fluorinated alkynylcyclopentenes

Reactions between 1,2-dichlorohexafluorocyclopentene and Ru(CCH)(dppe)Cp∗ or Ru(CCCCLi)(dppe)Cp∗ have given Ru(CC-c-C₅F₆Cl-2)(dppe)Cp∗ 4 and Ru(CCCC-c-C₅F₆Cl-2)(dppe)Cp∗ 7, respectively. Ready hydrolysis of 4 to the ketone Ru{CC[c-C₅F₄Cl(O)]}(dppe)Cp∗ 5 occurs, which can be converted to Ru{CC(c-C₅F₄Cl[C(CN)₂])}(dppe)Cp∗ 6 by treatment with CH₂(CN)₂/basic alumina. Spectroscopic, electrochemical and XRD structural studies for 4-7 are reported: for 6, these suggest that the cyanated fluorocarbon ligand is a very powerful electron-withdrawing group.     

Synthesis, structures and some reactions of Ru(CCCCFc)(PP)Cp (PP = dppm, dppe) and related compounds

The compounds Ru(CCCCFc)(PP)Cp [PP = dppe (1), dppm (2)], have been obtained from reactions between RuCl(PP)Cp and FcCCCCSiMe₃ in the presence of KF (1) or HCCCCFc and K[PF₆] (2), both with added dbu. The dppe complex reacts with Co₂(CO)₆(L₂) [L₂ = (CO)₂, dppm] to give 3, 4 in which the Co₂(CO)₄(L₂) group is attached to the outer CC triple bond. The PPh₃ analogue of 3 (5) has also been characterised. In contrast, tetracyanoethene reacts to give two isomeric complexes 6 and 7, in which the cyano-olefin has added to either CC triple bond. The reaction of RuCl(dppe)Cp with HCCCCFc, carried out in a thf/NEt₃ mixture in the presence of Na[BPh₄], gave [Ru{CCC(NEt₃)CHFc}(dppe)Cp]BPh₄ (8), probably formed by addition of the amine to an (unobserved) intermediate butatrienylidene [Ru(CCCCHFc)(dppe)Cp]⁺. The reaction of I₂ with 8 proceeds via an unusual migration of the alkynyl group to the Cp ring to give [RuI(dppe){η-C₅H₄CCC(NEt₃)CHFc}]I₃ (9). Single-crystal X-ray structural determinations of 1, 2 and 4-9 are reported.     

Synthesis and characterisation of a diphosphaalkene, a diphosphaalkyne and the first diphosphavinyl lithium complex

The preparation and characterisation of a diphosphaalkene, (Me₃Si)PC(OSiMe₃){C(C₂H₄)₃C}C(OSiMe₃)P(SiMe₃), and the second example of a diphosphaalkyne, PC{C(C₂H₄)₃C}CP, are described. In addition, the reaction of another diphosphaalkyne, PC{C(C₆H₄)₃C}CP, with MeLi/LiBr in the presence of tmeda has given the first diphosphavinyl lithium complex, [MePC{Li₂Br(tmeda)₂}{C(C₆H₄)₃C}C{Li₂Br(tmeda)₂}PMe], which is stable at room temperature and has been crystallographically characterised.     

Further reactions of some bis(vinylidene)diruthenium complexes

Whereas {Ru(dppm)Cp*}₂(μ-CCCC) (2) is the only product formed by deprotonation of [{Ru(dppm)Cp*}₂{μ(CCHCHC)}]⁺ with dbu, a mixture of 2 with Ru{CCCHCH(PPh₂)₂[RuCp*]}(dppm)Cp* (3) and {Cp*Ru(PPh₂CHCCH-)}₂ (4) is obtained with KOBu^t. A similar reaction with [{Ru(dppm)Cp*}₂{μ(CCMeCMeC)}]⁺ (5) gave Ru{CCCMeCH(PPh₂)₂[RuCp*]}(dppm)Cp* (6). X-ray structures of 4, 5 and 6 confirm the presence of the 1-ruthena-2,4-diphosphabicyclo[1.1.1]pentane moiety, which is likely formed by an intramolecular attack of the deprotonated dppm ligand on C(1) of the vinylidene ligand. Protonation of {Ru(dppe)Cp*}₂(μ-CCCC) (8-Ru) regenerates its precursor [{Ru(dppe)Cp*}₂{μ(CCHCHC)}]²⁺ (7-Ru). Ready oxidation of the bis(vinylidene) complex affords the cationic carbonyl [Ru(CO)(dppe)Cp*]PF₆ (9) (X-ray structure).     

Iron(II) and iron(III) complexes containing ethynyl thiophene fragments

The synthesis of the new complexes Cp*(dppe)FeCC2,5-C₄H₂SR (Cp* = 1,2,3,4,5-pentamethylcyclopentadienyl; dppe = 1,2-bis(diphenylphosphino)ethane; 2a, R = CCH; 2b, R = CCSi(CH₃)₃; 2c, R = CCSi(CH(CH₃)₂)₃; 3a, R = CC2,5-C₄H₂SCCH; 3c, R = CC2,5-C₄H₂SCCSi(CH(CH₃)₂)₃) is described. The ¹³C NMR and FTIR spectroscopic data indicate that the π-back donation from the metal to the carbon rich ligand increases with the size of the organic π-electron systems. The new complexes were also analyzed by CV and the chemical oxidation of 2a and 3c was carried out using 1 equiv of [Cp₂Fe][PF₆]. The corresponding complexes 2a[PF₆] and 3c[PF₆] are thermally stable, but 2a[PF₆] was too reactive to be isolated as a pure compound. The spectroscopic data revealed that the coordination of large organic π-electron systems to the iron nucleus produces only a weak increase of the carbon character of the SOMO for these new organoiron(III) derivatives.     

Nitrile ligands for controlled synthesis of alkynyl-ruthenium based homo and hetero bimetallic systems

Wire like mono- and poly-nuclear molecules based on alkynyl ruthenium complexes whose core unit is trans-[Ru(CC-R)(R′CN)(dppe)₂][PF₆] are readily formed in soft conditions. The electronic dual character of the metallic unit, donor through the acetylide moiety, acceptor versus the nitrile ligand is exemplified through electrochemical studies of a series of ethynylferrocene and cyanoferrocene derivatives. A single crystal X-ray diffraction analysis of the [(dppe)₂(PhCC)Ru(NC-C₆H₄-CN)Ru(CCPh)(dppe)₂][2PF₆] bimetallic complex 5 shows that the global structure of such complexes consists of wire type dimetallic units. With the availability of this versatile, direct, and simple route, a new class of extended rigid rod systems of nanometric size with multilevel electron transfers is readily accessed.     

Direct addition of supercritical alcohols, acetone or acetonitrile to the alkenes without catalysts

The reactions of the alkenes with supercritical organic compounds under non-catalytic conditions were investigated. The H and CR₂OH, CH₂COCH₃ or CH₂CN of supercritical alcohols (CHR₂OH), acetone (CH₃COCH₃) or acetonitrile (CH₃CN) added to the CC bonds of alkenes form C-C bonds between the α-carbons of the supercritical organic compounds and the sp² carbons of the alkenes.     

Carbon-carbon and carbon-chlorine bond formation on reaction of iodine(III) reagents with the bis(alkynyl)palladium(II) motif, and structural chemistry of trans-Pd(CC-o-Tol)2(PMe2Ph)2] and trans-[PdCl(CC-o-Tol)(PMe2Ph)2]

Trans-di(ortho-tolylethynyl)bis(dimethylphenylphosphine)palladium(II) reacts above −20 °C with the iodonium reagent IPhCl₂ to give predominantly o-Tol-CC-Cl, above 15 °C with IPh₂(OTf) (OTf = triflate) to give o-Tol-CC-Ph and (o-Tol-CC)₂ in ca. 3:1 ratio, and above 10 °C with IPh(CCR)(OTf) (R = Bu^t, SiMe₃) to give predominantly o-Tol-CC-CC-R and (o-Tol-CC)₂. ³¹P NMR spectra provide evidence for detection of intermediates. The complexes trans-[Pd(CC-o-Tol)₂(PMe₂Ph)₂] and trans-[PdCl(CC-o-Tol)(PMe₂Ph)₂] are obtained on reaction of trans-[PdCl₂(PMe₂Ph)₂] with Li(CC-o-Tol) and o-Tol-CCH/Et₃N, respectively, and have been characterised by X-ray crystallography.     

Evolution of lowest singlet and triplet excited states with transition metals in group 10-12 metallaynes containing biphenyl spacer

A new series of thermally stable group 10 platinum(II) and group 12 mercury(II) poly-yne polymers containing biphenyl spacer trans-[-Pt(PBu₃)₂CC(p-C₆H₄)₂CC-]_n and [HgCC(p-C₆H₄)₂CC-]_n were prepared in good yields by Hagihara’s dehydrohalogenation reaction of the corresponding metal chloride precursors with 4,4′-diethynylbiphenyl HCC(p-C₆H₄)₂CCH at room temperature. We report the optical spectroscopy of these polymetallaynes and compare the results with their bimetallic model complexes trans-[Pt(Ph)(PEt₃)₂CC(p-C₆H₄)₂CCPt(Ph)(PEt₃)₂] and [MeHgCC(p-C₆H₄)₂CCHgMe] as well as the group 11 gold(I) counterpart [(PPh₃)AuCC(p-C₆H₄)₂CCAu(PPh₃)]. The structural properties of all model complexes have been studied by X-ray crystallography. The influence of the heavy metal atom in these metal alkynyl systems on the intersystem crossing rate and the spatial extent of lowest singlet and triplet excitons is systematically characterized. Our investigations indicate that the organic triplet emissions can be harvested by the heavy-atom effect of group 10-12 transition metals (viz., Pt, Au, and Hg) which enables efficient intersystem crossing from the S₁ singlet excited state to the T₁ triplet excited state.