Synthesis and reactivity of 9,10-bis(4-trimethylsilylethynylbuta-1,3-diynyl)anthracene derived chromophores.

9,10-Bis(4-trimethylsilylethynylbutadiynyl)anthracene is readily availabe from the reaction of anthraquinone and LiCCCCSiMe3 followed by reduction with Sn(II) and serves as a convenient building block via desilylation and palladium-mediated C-C coupling processes for the construction of further butadiynylanthracenes terminated by metal complexes, arenes, haloarenes and alkynyl functionalities.

Organometallic flow chemistry: solvento complexes.

Photolysis under optimised flow conditions of metal carbonyls [{Ln}M(CO)x] [{Ln}M(CO)x = Cr(CO)6, Mo(CO)6, W(CO)6, Mn(CO)3(η-C5H4Me), Re(CO)3(η-C5H5)] in tetrahydrofuran (THF) conveniently affords the synthetically versatile and labile solvento complexes [{Ln}M(CO)x-1(THF)], thereby obviating many of the caveats associated with photochemical syntheses using either 'batch' or falling film techniques. Conversions were optimised and yields assayed by a combination of in situ infrared spectroscopy and derivatisation as the corresponding triphenylphosphine complexes [{Ln}M(CO)x-1(PPh3)].

Arsinocarbyne reactivity.

The reactivity of the tungsten diphenylarsinocarbyne [W(CAsPh2)(CO)2(Tp*)] (1; Tp* = hydrotris(dimethylpyrazolyl)borato) is described. The pyramidal arsenic coordinates to a selection of 5d metal centres, forming heterobi- or trimetallic complexes with osmium(II), iridium(III), platinum(II) and gold(I). In the latter case, the WC bond provides a competitive site for gold(I) coordination. Treatment with MeOSO2CF3 results in methylation at arsenic to give the first example of an arsoniocarbyne, [W(CAsPh2CH3)(CO)2(Tp*)]O3SCF3, for which only the WC bond remains available for gold(I) coordination.

Bimetallic ethynylanthracenyl functionalised carbynes.

Mono- and bimetallic anthracenes functionalised by alkynyl and alkylidynyl substituents are obtained via sequential cross-coupling reactions of the 9-bromoanthracenyl carbyne [W{CC(C6H4)2CBr}(CO)2(Tp*)].

Symmetric and non-symmetric anthracen-diyl bis(alkylidynes).

Three examples of 9-bromo-10-(alkylidynyl)anthracenes, [W{CC(C6H4)2CBr}(CO)2(L)] (L = hydrotris(dimethylpyrazol-1-yl)borate Tp*, hydrotris(pyrazol-1-yl)borate Tp, hydrotris(2-mercapto-N-methylimidazol-1-yl)borate Tm) were prepared via modified Fischer-Mayr acyl oxide-abstraction protocols. With a sufficiently bulky ancillary ligand (L = Tp*) the aryl bromide is ammenable to cross-coupling reactions that enable more elaborate derivatives to be prepared. These including symmetric bis(alkylidynyl)anthracenes as well as non-palindromic examples bearing disparate metals and/or co-ligands. In contrast, these couplings fail for smaller ligands (L = Tp, Tm) where it was found that Pd0 or Pt0 were instead able to coordinate across two WC bonds to give trimetallic bow-tie complexes, [W2M{µ-CC(C6H4)2CBr}2(CO)4(L)2] (M = Pd, Pt; L = Tp, Tm).

Heterocyclic arsinocarbynes via tandem transmetallation.

Gold(i)-catalysed tandem transmetallation (Sn→Au→As) of the stannylcarbyne [W(≡CSnnBu3)(CO)2(Tp*)] (Tp* = hydrotris-(dimethylpyrazolyl)borate) with haloarsines gives direct access to a range of novel arsinocarbyne complexes, LnM≡CAsR2, including unusual heterocyclic phenarsazininyl and arsolyl examples.

Pnictogen-Functionalised C1 Ligands: MC-ARn (n=0, 1, 2, 3).

The chemistry of transition metal carbynes, Ln M≡CR, has historically been dominated by species bearing hydrocarbyl or amino 'R' substituents, with other elements appearing only sporadically. In recent years, carbynes and related 'C1 ' species bearing other main-group substituents, particularly heavier elements of the p-block, have begun to emerge. This review details the chemistry of heavier pnictogen-functionalised C1 ligands, MCARn (A=P, As, Sb, Bi; n=0-3), including their syntheses, properties and reactivities, and how these are distinguished from more traditional carbyne complexes. Recent developments in the closely related phospha-isonitrile Ln M(CPR), cya-phosphide and cya-arside ligands, Ln M(C≡A) (A=P, As), are also discussed.

Carbyne decorated porphyrins.

The Pd0/AuI-mediated coupling between stannylcarbyne [W([triple bond, length as m-dash]CSnnBu3)(CO)2(Tp*)] (1) and meso-5,10,15,20-tetrakis(3' or 4'-bromophenyl)porphyrins gives tetrametallic derivatives where a central porphyrin unit is formally substituted at the four meso positions by tungsten benzylidyne moieties. These new 'metallo-porphyrins' undergo metallation at the porphyrin centres with Zn(OAc)2·2H2O to give a pentametallic W4Zn complex or at the tungsten-carbon triple bonds with [AuCl(SMe2)] to give an octametallic W4Au4 complex. The Zn(ii)-metalloporphyrin derivatives are capable of reversibly coordinating further axial ligands such as 4-dimethylaminopyridine or meta-pyridylcarbynes, which themselves are prepared via a coupling between 1 and the appropriate (di)bromopyridine.

Advances in Transition Metal Seleno- and Tellurocarbonyl Chemistry.

In contrast to the ubiquity of transition-metal carbonyl, and (to a lesser extent) thiocarbonyl complexes, transition-metal complexes of carbon monoselenide Ln MCSe and monotelluride Ln MCTe remain scarce. The last few years, however, have seen notable steps towards expanding this chemistry, specifically with regards to new systematic studies on homologous sets of chalcocarbonyl complexes Ln MCE (E=O, S, Se, Te), the first reports of new bi- and polynuclear CSe and CTe bridging complexes and a confluence with metal carbido chemistry. Herein the properties, syntheses and reactions of these rare but fundamentally intriguing compounds are discussed.

In Search of Fulminate Analogues: Ln M≡CP=NR.

The "CPNR" ligand may be viewed as being isolobal with fulminate, CNO; however, attempts to prepare a complex of such a ligand resulted instead in a range of novel imino and aminophosphinocarbyne complexes. Sequential treatment of [Mo(≡CBr)(CO)2 (Tp*)] (Tp*=hydrotris(dimethylpyrazolyl)borate) with nBuLi and ClP=NMes* (Mes*=C6 H2 tBu3 -2,4,6) afforded mixtures of the complexes [Mo(≡CPnBuNHMes*)(CO)2 (Tp*)] and traces of the bimetallic products [Mo2 {µ2 -C2 P2 O(NHMes)2 }(CO)4 (Tp*)2 ] and [Mo2 (µ2 -C2 PNHMes)(CO)4 (Tp*)2 ]. The reaction of [W(≡CBr)(CO)2 (Tp*)] with nBuLi and ClP=NMes* afforded predominantly the mononuclear carbyne [W{≡CP(=NMes*)nBu2 })(CO)2 (Tp*)] and traces of the binuclear complex [W2 (µ-C2 PNHMes)(CO)4 (Tp*)2 ] which is also obtained when tBuLi is used. Although not isolable, the intended complexes [M(≡CPNMes*)(CO)2 (Tp*)] could be generated in situ and spectroscopically characterized via the reactions of the stannyl carbynes [M(≡CSnnBu3 )(CO)2 (Tp*)] and ClP=NMes*. The preceding observations are mechanistically interpreted with reference to a computational interrogation of the model complex [Mo(≡CP=NCH3 )(CO)2 (Tp*)], the LUMO of which has considerable phosphorus character.

Propargylidyne and Pentadiynylidyne Polyfunctionalised Polycyclic Aromatic Hydrocarbons.

The Pd0 /AuI mediated [C1 +C2 ] cross-coupling reactions of [W(≡CBr)(CO)2 (Tp*)] (Tp*=hydrotris(dimethylpyrazolyl)borate) and trimethylsilylethynyl-substituted arenes afford new polycyclic aromatic hydrocarbon propargylidynes [W(≡CC≡CR)(CO)2 (Tp*)] (R=9-anthracenyl, 1-pyrenyl). The strategy extends to the first bis(propargylidyne) and bis(pentadiynylidyne) complexes bridged by phenyl or anthracenyl spacers, and to a tetrakis(propargylidyne) connected through a pyrene core.

Metal coordination to bipyridyl carbynes.

The Pd0/AuI-mediated coupling of the stannylcarbyne [W([triple bond, length as m-dash]CSnnBu3)(CO)2(Tp*)] (1) and 6-bromo-2,2'-bipyridine or 6,6'-dibromo-2,2'-bipyridine gives new carbynes functionalised on the carbyne carbon(s) with a bipyridyl group. These new 'metallo-ligands' undergo protonation at the pyridyl nitrogens, metallation of the tungsten-carbon triple bond with [AuCl(SMe2)], and metallation of the bipyridyl moiety with K[PtCl3(C2H4)]·H2O, [ReBr(CO)5] and [MCl(COD]2 (M = Ir, Rh; COD = η4-cycloocta-1,5-diene).

Semi-bridging σ-silyls as Z-type ligands.

The reactions of SiHPh(NCH2PPh2)2C6H4-1,2 with a range of zerovalent group 10 reagents afford the homoleptic bimetallic complexes [M2{µ-κ3-Si,P,P'-SiPh(CH2PPh2)2C6H4}2] (M = Ni, Pd, Pt) in which the M-M bond is unsymmetrically bridged by two σ-silyl groups. The asymmetry of the M2Si2 core increases from Ni through Pd to Pt and is consistent with a bonding description in which one metal acts as an electron pair donor to a trigonal bipyramidal 'Z-type' silicon centre, reminsicent of semi-bridging coordination by CO, carbynes and boryl ligands.

Bi- and poly(carbyne) functionalised polycyclic aromatics.

Complexes where a central polyaromatic ring system is substituted with one to four tungsten carbynes have been prepared by Pd0/AuI-mediated coupling between a tungsten stannylcarbyne and aryl halides. This strategy enables preparation of complexes with one to three carbynes substituted onto a single phenyl ring, the first anthracenyl mono- and bis-carbynes, and a tetra(carbyne) complex constructed about a central pyrene ring system.

Bridging selenocarbonyl ligands: an open and shut case.

Novel bis(isoselenocarbonyl) complexes [W2Pt(µ-CSe)2(CO)4(L2)(Tp*)2] (L2 = cyclooctadiene, norbornadiene) eliminate the diene upon heating to provide [W2Pt(µ-CSe)2(CO)4(Tp*)2], in which the CSe ligands close to bridge W-Pt bonds in a σ-π mode that may be re-opened by addition of new ligands (CNR: R = tBu, C6H2Me3) to re-establish the isoselenocarbonyl coordination in [W2Pt(µ-CSe)2(CO)4(CNR)2(Tp*)2].

Synthesis of pyridyl carbyne complexes and their conversion to N-heterocyclic vinylidenes.

A new synthetic approach to hetero-aryl substituted carbyne complexes has allowed the synthesis of pyridyl functionalised carbynes and bis(carbynes), alkylation of which affords the first N-heterocyclic vinylidene complexes.

Hydrogenating an organometallic carbon chain: buten-yn-diyl (CH[double bond, length as m-dash]CHC[triple bond, length as m-dash]C) as a missing link.

The sequential reaction of [Ru(C[triple bond, length as m-dash]CC[triple bond, length as m-dash]CH)Cl(CO)2(PPh3)2] with [Ru(CO)2(PPh3)3], and N-chlorosuccinimide affords the binuclear tetracarbido complex [Ru2(µ-C[triple bond, length as m-dash]CC[triple bond, length as m-dash]C)Cl2(CO)4(PPh3)4]. This may be compared with the first example of a butenyndiyl bridged bimetallic complex [Ru2(µ-CH[double bond, length as m-dash]CHC[triple bond, length as m-dash]C)Cl2(CO)4(PPh3)4] which is obtained from the reaction of [Ru(C[triple bond, length as m-dash]CC[triple bond, length as m-dash]CH)Cl(CO)2(PPh3)2] with [RuHCl(CO)(PPh3)3] followed by carbonylation. Characterisational data are discussed with reference to constituent model complexes [Ru(C[triple bond, length as m-dash]CH)Cl(CO)2(PPh3)2] and [Ru(CH[double bond, length as m-dash]CH2)Cl(CO)2(PPh3)2] in addition to DFT analysis of the bonding in the complexes [Ru2(µ-L)Cl2(CO)4(PMe3)4] (L = C[triple bond, length as m-dash]C-C[triple bond, length as m-dash]C, CH[double bond, length as m-dash]CHC[triple bond, length as m-dash]C, CH[double bond, length as m-dash]CH-CH[double bond, length as m-dash]CH). A range of other tetracarbido complexes which may be prepared from [RuCl(C[triple bond, length as m-dash]CC[triple bond, length as m-dash]CH)(CO)2(PPh3)2] is also described and includes [RuAu(µ-C4)Cl(CO)3(PPh3)3], [RuIr(µ-C4)Cl(CO)3(PPh3)4], [RuIr(µ-C4)H(NCMe)(CO)3(PPh3)4]BF4, [RuIr(µ-C4)Cl(η2-O2)(CO)3(PPh3)4], [Ru2Hg(µ-C4)2Cl2(CO)4(PPh3)4], [Ru2Pt(µ-C4)2Cl2(CO)4(PPh3)6] and [Ru2(µ-C4)HCl(CO)4(PPh3)4].

Tungsten-platinum µ-carbido and µ-methylidyne complexes.

Reactions of the lithiocarbyne [W][triple bond, length as m-dash]CLi ([W] = W(CO)2(Tp*); Tp* = tris(dimethylpyrazolyl)borate) with divalent platinum complexes [PtCl(terpy)]PF6, [PtCl2(η-C4R4)] (R = Me, Et), and [PtCl2(phen)] afford access to µ-carbido, µ-methylidyne and carbyne-based metallo-ligand complexes [Pt(C[triple bond, length as m-dash][W])(terpy)]PF6, [Pt(µ-HC[triple bond, length as m-dash][W])2] and [Pt(C[triple bond, length as m-dash][W])Cl(phen-C[triple bond, length as m-dash][W]-2)], respectively, the last of which provides a rare example of intermolecular organometallic nucleophilic attack at coordinated phenanthroline.

Bi- and Polynuclear Transition-Metal Carbon Tellurides.

The first examples of bi- and polynuclear tellurocarbonyl complexes were obtained from the reactions of [W(≡CTe)(CO)2 (Tp*)]NEt4 (Tp*=hydrotris(dimethylpyrazolyl)borate) with [MCl(PCy3 )]/TlPF6 (M=Cu, Au) or [Au2 Cl2 (µ-dppm)], which afford [WM(µ-CTe)(PCy3 )(CO)2 (Tp*)] (M=Cu, Au) and [WAu2 (µ-CTe)(µ-dppm)(CO)2 (Tp*)]3 (PF6 )3 . In all cases it is specifically the tellurocarbonyl that assumes a bridging, but in each case distinct, role including examples of isotellurocarbonyl, semi-bridging and σ-π coordination and combinations thereof. Tetrametallic complexes bridged by C2 Te and C2 Te2 ligands are also described.

Metal coordination to a dimetallaoctatetrayne.

The reactions of the ditungstaoctatetrayne [(Tp*)(CO)2W([triple bond, length as m-dash]CC[triple bond, length as m-dash]CC[triple bond, length as m-dash]CC[triple bond, length as m-dash])W(CO)2(Tp*)] with several metal complexes have been investigated. Addition of [Co2(CO)8] occurs across the internal C[triple bond, length as m-dash]C bonds, whereas [AuCl(SMe2)] initially delivers 'AuCl' across the W[triple bond, length as m-dash]C carbyne bonds before undergoing further reaction to oxidise the tungsten and replace the carbonyl ligands with chloride in [(Tp*)Cl2W([triple bond, length as m-dash]CC[triple bond, length as m-dash]CC[triple bond, length as m-dash]CC[triple bond, length as m-dash])WCl2(Tp*)] with retention of the ditungstaoctatetrayne bridge. Reaction with [AuCl(PR3)] (R = Ph, Cy) in the presence of AgPF6 prevents this oxidation and adds [AuPR3]+ across the W[triple bond, length as m-dash]C bonds to give dicationic derivatives. Finally, the reaction with [Pt(nbe)3] (nbe = norbornene, bicyclo[2.2.1]hept-2-ene) and 1,5-cyclooctadiene (COD) adds a 'Pt(COD)' unit to one or both tungsten-carbon bonds, allowing both the mono- and diplatinum complexes to be isolated.