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.     

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.     

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.     

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.     

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.     

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.     

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, 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.