Polyfluorophenylgold(I) complexes

Neutral polyfluorophenyl complexes of the type RAuL and RAuL-LAuR and anionic complexes of the type [AuR₂]^? (R = 2,3,5,6-C₆F₄H, 2,4,6-C,F₃H₂, 3,6-C₆F₂H₃, 4-C₆ FH₄ or 3-CF₃C,H₄) are obtained by the reaction of ClAuL (L = PPh₃, P(cyclohexyl)₃, AsPh₃ or tetrahydrothiophen; L-L = Ph₂PCH₂PPh₂ or Ph₂PCH₂CH₂PPPh₂) with an organolithium derivative and/or the replacement of the initial ligands L by other mono- or bi-dentate ligands.The outcome of the reaction of [AuR₂]^? with [Au(PCy₃)₂]⁺ (Cy = cyclohexyl), depends on the nature of the ligand R; thus with R = 3,6-C₆,F₂H₃ the product is [Au(PCy₃)₂][AuR₂], while with R = 2,4,6-C₆F₃H₂, the product is [Au(PCy₃)(2,4,6-C₆F₃H₂)].     

Heterobimetallische phosphanido-verbrückte Zweikern-Komplexe - Synthese von cis-rac-[(η-C5H4R)2Zr{μ-PH(2,4,6−iPr3C6H2)}2M(CO)4] (RMe,MCr,Mo; RH,MMo)

Heterobimetallic Phosphanido-bridged Dinuclear Complexes - Syntheses of cis-rac-[(η-C₅H₄R)₂Zr{μ-PH(2,4,6-ⁱPr₃C₆H₂)}₂M(CO)₄] (R?Me, M?Cr, Mo; R?H, M?Mo) The zirconocene bisphosphanido complexes [(η-C₅H₄R)₂Zr{PH(2,4,6-ⁱPr₃C₆H₂)}₂] (R?Me, H) react with [(NBD)M(CO)₄] (NBD?norbornadiene, M?Cr, Mo) to give only one diastereomer of the phosphanido-bridged heterobimetallic dinuclear complexes cis-rac-[(η-C₅H₄R)₂Zr{μ-PH(2,4,6-ⁱPr₃C₆H₂)}₂M(CO)₄] [R?Me, M?Cr ( 1 ), Mo ( 2 ); R?H, M?Mo ( 3 )]. However, no reaction was observed between [(η-C₅H₅)₂Zr{PH(2,4,6-^tBu₃ C₆H₂)}₂] and [Pt(PPh₃)₄]. 1—3 were characterised spectroscopically. For 1—3 , the presence of the racemic isomer was shown by NMR spectroscopy. No reaction was observed at room temperature for 3 and CS₂, (NO)BF₄, Me₃NO or PH(2,4,6-Me₃C₆H₂)₂. With Et₂AlH or PhC?CH decomposition of 3 was observed.     

Chlorobis(polyfluorophenyl)thallium(III) complexes and their reactions with gold(I) and tin(II) compounds

The reaction of TlCl₃ with RLi leads to complexes of the general formula TlR₂Cl (R = C₆F₅, p-C₆F₄H, m-C₆F₄H, 2,4,6-C₆F₃H₂, p-C₆FH₄ or m-CF₃C₆H₄). Some of these undergo oxidative addition reactions with gold(I) complexes to give polyfluorophenyl derivatives of the types AuR₂ClL and Au(C₆F₅)R₂(tht) (tht = tetrahydrothiophen), and with SnCl₂ to give oily materials from which stable solids of the general formula Q[SnR₂Cl₃] can be isolated by addition of QCl (Q = Et₄N or Ph₃BzP).     

ortho-, meta- and para-nitrophenylgold(I) complexes

Treatment of [BzPh₃P][AuCl₂] with [Hg(x-C₆H₄NO₂)₂] (x = o, m, or p) gives anionic gold(I) complexes of the type [BzPh₃P][Au(R)Cl](R = o-, m- or p-C₆H₄NO₂, Bz = C₆H₅CH₂). The chloro ligand in [Au(o-C₆H₄NO₂)Cl]^? can be replaced by bromo or iodo ligands by use of NaBr or NaI. The anions [Au(R)Cl]^? react with neutral monodentate ligands, L, to give neutral mononuclear complexes [Au(R)L] (R = o-C₆H₄NO₂, L = PPh₃, AsPh₃; R = m-C₆H₄NO₂, L = PPh₃) and with 1,2-bis(diphenylphosphino)ethane (dpe) to give [Au₂(R)₂(dpe)] (R = o-C₆H₄NO₂). The corresponding [Au(p-C₆H₄NO₂)Cl]^? reacts with PPh₃ or AsPh₃ to give mixtures containing [AuClL]. The anionic ortho-nitrophenylgold(I) complex is much more stable than its meta- or para-nitrophenyl isomers. These are thought to be the first reports of nitrophenylgold(I) complexes.     

Arene complexes [(η-C<Subscript>5</Subscript>H<Subscript>5</Subscript>)M(η-C<Subscript>6</Subscript>R<Subscript>6</Subscript>)]<Superscript>2+</Superscript> (M = Rh,Ir)

The dicationic arene complexes [CpM(arene)](BF₄)₂ (arene = C₆H₆, 1,3,5-C₆H₃Me₃, or C₆Me₆) were synthesized by the reactions of the solvated complexes [CpM(MeNO₂)₃](BF₄)₂ (M = Rh, Ir) with benzene and its derivatives. The solvated complexes were generated in situ by abstraction of I^– from [CpMI₂]₂ with AgBF₄. A procedure was developed for the synthesis of the iodide [CpRhI₂]₂ based on the reaction of the cyclooctadiene derivative CpRh(1,5-C₈H₁₂) with I₂. The structure of the [CpRh(C₆Me₆)](BF₄)₂ complex was established by X-ray diffraction analysis.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1871–1874, September, 2004.     

The Reactivity of Potassium Polyfluoroaryl‐, Polyfluoroalkenyl‐, and Perfluoroalkyltrifluoroborates and their Hydrocarbon Analogues towards Acids of Different Strength: A Systematic Study of the Hydrodeboration

The hydrodeboration of the (fluoroorgano)trifluoroborates K [R_FBF₃] [R_F = C₆F₅, XCF=CF (X = F, cis‐ and trans‐Cl, C₃F₇O, cis‐C₂F₅, trans‐C₄F₉, ‐C₄H₉) and C₆F₁₃] and of the organotrifluoroborates K [RBF₃] (R = C₆H₅, cis‐ and trans‐C₄H₉CH=CH, C₄H₉ and C₈H₁₇) with CH₃CO₂H (100 %), CF₃CO₂H (100 %), aqueous HF and anhydrous HF was investigated. In the alkenyltrifluoroborates K [R'CF=CFBF₃] the formal replacement of BF₃ by a proton occurred stereospecifically under retention of the configuration. The ¹⁹F NMR spectra of K [R_FBF₃] in acids indicate strong interactions of the BF₃ group with protons or acid molecules.     

Polythiolated complexes. Part 2(1). Palladium(II) and platinum(II) derivatives of polyfluorophenylthiolates

Summary The preparation and characterization of the new thiolate complexes [M(SR)₂(SEt₂)₂] (M=Pt, R=C₆F₅ orp-C₆HF₄) and [M(SR)₂]_n (M=Pd, R=C₆F₅,p-C₆HF₄ orp-C₆H₄F; M=Pt, R=p-C₆H₄F) is discussed. The tendency to form polymeric, rather than monomeric species, varies as follows: Pd>Pt; C₆H₄F>C₆HF₄> C₆F₅. [Pt(SC₆F₅)₂(SEt₂)₂] has atrans square planar coordination.     

Polyfluoroorganotrifluoroborates and -difluoroboranes: interesting materials in fluoroorgano and fluoroorgano-element chemistry

The aimed introduction of the polyfluoroorgano groups (4-C₅F₄N), C₆F₁₃C₂H₄, and C₂F₅ into methoxy group-containing boron electrophiles is reported. The new compounds obtained after transformations K[(4-C₅F₄N)BF₃], (4-C₅F₄N)BF₂, K[C₆F₁₃C₂H₄BF₃], C₆F₁₃C₂H₄BF₂, K[(C₂F₅)₂B(OMe)₂], and K[(C₂F₅)₂BF₂] were isolated and characterised. Additionally some of their precursors as there are Li(4-C₅F₄N), Li[(4-C₅F₄N)B(OMe)₃], (4-C₅F₄N)B(OH)₂ and the by-products Li[(4-C₅F₄N)₂B(OMe)₂], (4-C₅F₄N)₂BOH, and K[(4-C₅F₄N)₂BF₂] are described. The usefulness of polyfluoroorganodifluoroboranes for introducing polyfluoroorgano groups into hypervalent FEF bonds is demonstrated by the synthesis of [C₆F₅(4-C₅F₄N)I][BF₄] and [p-FC₆H₄(trans-CF₃CFCF)I][BF₄].     

Photoinitiated Reactions of Haloperfluorocarbons with Gold(I) Organometallic Complexes: Perfluoroalkyl Gold(I) and Gold(III) Complexes

The study of perfluoroalkyl metal complexes is key to understand and improve metal-promoted perfluoroalkylation reactions. Herein, we report the synthesis of the first gold complexes with primary or secondary perfluoroalkyl ligands by photoinitiated reactions between Au^I organometallic complexes and iodoperfluoroalkanes. Complexes of the types LAuR_F (L=PPh₃ or N,N-bis(2,6-diisopropylphenyl)imidazol-2-ylidene; R_F=n-C₄F₉, n-C₆F₁₃, i-C₃F₇, c-C₆F₁₁) and [Au(R_F)(Ar)I(PPh₃)] (Ar=2,4,6-trimethylphenyl) have been isolated and characterized. Alkynes R_FC≡CR were formed by reaction of Ph₃PAuC≡CR (R=Ph, nHex) with IR_F (R_F=n-C₄F₉, i-C₃F₇). According to the evidences obtained, this transformation undergoes through a photoinitiated radical mechanism. Au^III complexes [Au(n-C₄F₉)(X)(Y)L] (X=Y=Cl, Br, I, Me; X=Me, Y=I) have been prepared or in situ generated, and their thermal or photochemical decomposition reactions have been studied.     

π-complexes of monoanionic carborane ligand [9-(Me2S)-7,8-C2B9H10]− with [η-C5R5Fe]+ (R=H, Me) and [η-C4Me4Co]+ cationic fragments

Compounds (η-C₅R₅)Fe[η-9-(Me₂S)-7,8-C₂B₉H₁₀] (R=H, Me) and (η-C₄Me₄)Co[η-9-(Me₂S)-7,8-C₂B₉H₁₀] were synthesized by the reactions of Na[9-(Me₂S)-7,8-C₂B₉H₁₀] with complexes [(η-C₅H₅)Fe(MeCN)₃]PF₆, [(η-C₅Me₅)Fe(MeCN)₃]BF₄, and [(η-C₄Me₄)Co(MeCN)₃]PF₆, respectively. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 177–179, January, 1999.     

Exploring the Reactivity of B-Connected Carboranylphosphines in Frustrated Lewis Pair Chemistry: A New Frame for a Classic System

The primary phosphines MesPH₂ and tBuPH₂ react with 9-iodo-m-carborane yielding B9-connected secondary carboranylphosphines 1,7-H₂C₂B₁₀H₉-9-PHR (R=2,4,6-Me₃C₆H₂ (Mes; 1 a ), tBu ( 1 b )). Addition of tris(pentafluorophenyl)borane (BCF) to 1 a , b resulted in the zwitterionic compounds 1,7-H₂C₂B₁₀H₉-9-PHR(p-C₆F₄)BF(C₆F₅)₂ ( 2 a , b ) through nucleophilic para substitution of a C₆F₅ ring followed by fluoride transfer to boron. Further reaction with Me₂SiHCl prompted a H−F exchange yielding the zwitterionic compounds 1,7-H₂C₂B₁₀H₉-9-PHR(p-C₆F₄)BH(C₆F₅)₂ ( 3 a , b ). The reaction of 2 a , b with one equivalent of R'MgBr (R’=Me, Ph) gave the extremely water-sensitive frustrated Lewis pairs 1,7-H₂C₂B₁₀H₉-9-PR(p-C₆F₄)B(C₆F₅)₂ ( 4 a , b ). Hydrolysis of the B−C₆F₄ bond in 4 a , b gave the first tertiary B-carboranyl phosphines with three distinct substituents, 1,7-H₂C₂B₁₀H₉-9-PR(p-C₆F₄H) ( 5 a , b ). Deprotonation of the zwitterionic compounds 2 a , b and 3 a , b formed anionic phosphines [1,7-H₂C₂B₁₀H₉-9-PR(p-C₆F₄)BX(C₆F₅)₂]⁻[DMSOH]⁺ (R=Mes, X=F ( 6 a ), R=tBu, X=F ( 6 b ); R=Mes, X=H ( 7 a ), R=tBu, X=H ( 7 b )). Reaction of 2 a , b with an excess of Grignard reagents resulted in the addition of R’ at the boron atom yielding the anions [1,7-H₂C₂B₁₀H₉-9-PR(p-C₆F₄)BR’(C₆F₅)₂]⁻ (R=Mes, R’=Me ( 8 a ), R=tBu, R’=Me ( 8 b ); R=Mes, R’=Ph ( 9 a ), R=tBu, R’=Ph ( 9 b )) with [MgBr(Et₂O)_n]⁺ as counterion. The ability of the zwitterionic compounds 3 a , b to hydrogenate imines as well as the Brønsted acidity of 3 a were investigated.     

Reaktionen der Cycloheptatrienylkomplexe [η7-C7H7W(CO)3]BF4 und η7-C7H7Mo(CO)2 Br mit Neutralliganden und die elektrochemische Reduktion des Wolframkomplexes

Reactions of the Cycloheptatrienyl Complexes [η⁷-C₇H₇W(CO)₃]BF₄ and η⁷-C₇H₇Mo(CO)₂Br with Neutral Ligands and the Electrochemical Reduction of the Wolfram Complex Compounds of the type [η⁷-C₇H₇M(CO)₂L][BF₄] (L = P(C₆H₅)₃, As(C₆H₅)₃, Sb(C₆H₅)₃ for M = W and L = N₂H₄ for M = Mo) were synthesized and characterisized. The iodide η⁷-C₇H₇W(CO)₂I reacts with the diphosphine ((C₆H₅)₂PCH₂)₂ to give the trihapto complex η³-C₇H₇ W(CO)₂I((C₆H₅)₂PCH₂)₂. In the case of η⁷-C₇H₇Mo(CO)₂ Br reaction with hydrazine leads to the substitution product [η⁷-C₇H₇ Mo(CO)₂N₂H₄]^⊕, which can be stabilized by large anions. The binuclear complex [C₇H₇W(CO)₃]₂ has been synthesized electrochemically.     

From hypervalent xenon difluoride and aryliodine(III) difluorides to onium salts: Scope and limitation of acidic fluoroorganic reagents in the synthesis of fluoroorgano xenon(II) and iodine(III) onium salts

Fluorinated organodifluoroboranes R_fBF₂ are in general suitable reagents to transform XeF₂ and RIF₂ into the corresponding onium tetrafluoroborate salts [R_fXe][BF₄] and [R(R_f)I][BF₄], respectively. (4-C₅F₄N)BF₂ and trans-CF₃CFCFBF₂ which represent boranes of high acidity form no Xe-C onium salts in reactions with XeF₂ but give the desired iodonium salts with RIF₂ (R = C₆F₅, o-, m-, p-C₆FH₄). The reaction of (4-C₅F₄N)BF₂ with XeF₂ ends with a XeF₂-borane adduct. C₆F₅Xe(4-C₅F₄N), the first Xe-(4-C₅F₄N) compound, was obtained when C₆F₅XeF was reacted with Cd(4-C₅F₄N)₂. We describe the synthesis of (4-C₅F₄N)IF₂ and reactions of (4-C₅F₄N)IF₂ and C₆F₅IF₂ with (4-C₅F₄N)BF₂. Analogous to [(4-C₅F₄N)₂I][BF₄] and [C₆F₅(4-C₅F₄N)I][BF₄] aryl(perfluoroalkenyl)iodonium salts [R(R′)I][BF₄] were obtained from RIF₂ (R = C₆F₅, o-, m-, p-C₆FH₄) and R′BF₂ (R′ = trans-CF₃CFCF, CF₂CF). The gas phase fluoride affinities pF⁻ of selected fluoroorganodifluoroboranes R_fBF₂ and their hydrocarbon analogs are calculated (B3LYP/6-31+G^*) and discussed with respect to their potential to introduce R_f-groups into hypervalent EF₂ bonds. Four aspects which influence the transformation of hypervalent EF₂ bonds (E = Xe, R′I) under the action of Lewis acidic reagents RAF_n−1 (A = B, P; n = 3, 5) into the corresponding [RE][AF_n+1] salts are presented and the important role of the acidity is emphasized. Fluoride affinities may help to plan the introduction of organo groups into EF₂ moieties and to expand the types of acidic reagents. Thus C₆H₅PF₄ with a pF⁻ value comparable to that of R_fBF₂ compounds is able to introduce the C₆H₅ group into RIF₂ (R = C₆F₅, p-C₆FH₄).     

A new application of (polyfluoroorgano)trifluoroborate salts: the palladium-catalysed cross-coupling reaction with substituted benzenediazonium tetrafluoroborates

For the first time (polyfluoroorgano)trifluoroborate salts, namely K[C₆F₅BF₃], K[C₆HF₄BF₃] (all three isomers), K[3,4,5-C₆H₂F₃BF₃], and K[CF₂CFBF₃] were principally applied as reagents to Pd-catalysed cross-coupling reactions. A series of polyfluorinated biphenyls C₆H_5−nF_n-C₆H₄X-4′ were obtained from K[C₆H_5−nF_nBF₃] and the substrates [4-XC₆H₄N₂][BF₄] in the presence of Pd catalysts. The influence of the number and the position of the fluorine atoms in the (polyfluorophenyl)trifluoroborate salts on the reactivity in the coupling reaction was elucidated. In addition to (polyfluorophenyl)trifluoroborate salts, the cross-coupling was expanded to a first example of a perfluoroalkenyl reagent. K[CF₂CFBF₃] reacted with [4-FC₆H₄N₂][BF₄] and formed CF₂CF-C₆H₄F-4.     

A first methodical approach to salts with unsymmetrical fluorophenyl(pentafluorophenyl)difluoroiodonium(V) cations [Rf(RF)IF2] (Rf=x-FC6H4, x=2, 3, 4; RF=C6F5)

A promising approach to the unknown type of [Ar′(Ar)IF₂]X salts is offered. x-FC₆H₄IF₄ (x=2, 3, 4) reacts with C₆F₅BF₂ in CH₂Cl₂ and forms [x-FC₆H₄(C₆F₅)IF₂][BF₄] salts in good yields. For [4-FC₆H₄(C₆F₅)IF₂][BF₄] the fluoro-oxidizer property is shown in reactions with weakly reducing agents like E(C₆F₅)₃ (E=P, As, Sb, Bi) and ArI (Ar=4-FC₆H₄, C₆F₅). The fluorine/aryl substitution method is also applied to the synthesis of [(4-FC₆H₄)₂IF₂][BF₄], an example with two identical aryl groups in the difluoroiodonium(V) moiety.     

Demercuriation reactions of the complexes [(PPh3)2RPtHgR′] containing platinum-mercury bonds

The compounds [(PPh₃)₂,RPtHgR′] (R = CH₃, R′= 2,5-C₆H₃Cl₂, 2,3,4- and 2,4,6-C₆H₂Cl₃, 2,3,4,5-, 2,3,4,6- and 2,3,5,6-C₆HCl₄, C₆Cl₅; R = Et, R′ = 2,5-C₆H₃Cl₂, 2,4,6-C₆H₂Cl₃; R = 2-C₆H₄Cl, R′=2-C₆H₄(CH₃)) have been prepared by the reactions of RHgR′ with Pt(PPh₃)₃, in order to study their possible use as intermediates in the preparation of diorganoplatinum complexes with different organic ligands. The dependence of J(³¹P-¹⁹⁵Pt) on slight differences in the electronic character of the ligand R′ in the series of compounds [(PPh₃)₂(CH₃)Pt-HgR′] has been studied.     

Preparation and properties of new ferrocenyl heterobimetallic complexes with counterion dependent NLO responses

New ferrocenyl-based bimetallic cationic compounds of the type of (E)-[CpFe(η⁵-C₅H₄)(CHCH)(C₆H₄)CNRuCp(PPh₃)₂]X (X=PF₆, BF₄) and of (E)-[CpFe(η⁵-C₅H₄)(CHCH)(C₆H₄)CNFeCp(CO)₂]PF₆ have been obtained and characterized. The crystal structure of (E)-[CpFe(η⁵-C₅H₄)(CHCH)(C₆H₄)CNRuCp(PPh₃)₂]BF₄ has been established by means of X-ray diffractometry. The NLO responses of the compounds have been studied by the hyper-Rayleigh scattering technique and the hyperpolarizability is found to be dependent on the nature of the counterion.     

Further Evidence for ‘Extended’ Cumulene Complexes: Derivatives from Reactions with Halide Anions and Water

Reactions of [Ru{C=C(H)-1,4-C₆H₄C≡CH}(PPh₃)₂Cp]BF₄ ([ 1 a ]BF₄) with hydrohalic acids, HX, results in the formation of [Ru{C≡C-1,4-C₆H₄-C(X)=CH₂}(PPh₃)₂Cp] [X=Cl ( 2 a-Cl ), Br ( 2 a-Br )], arising from facile Markovnikov addition of halide anions to the putative quinoidal cumulene cation [Ru(=C=C=C₆H₄=C=CH₂)(PPh₃)₂Cp]⁺. Similarly, [M{C=C(H)-1,4-C₆H₄-C≡CH}(LL)Cp ]BF₄ [M(LL)Cp’=Ru(PPh₃)₂Cp ([ 1 a ]BF₄); Ru(dppe)Cp* ([ 1 b ]BF₄); Fe(dppe)Cp ([ 1 c ]BF₄); Fe(dppe)Cp* ([ 1 d ]BF₄)] react with H⁺/H₂O to give the acyl-functionalised phenylacetylide complexes [M{C≡C-1,4-C₆H₄-C(=O)CH₃}(LL)Cp’] ( 3 a – d ) after workup. The Markovnikov addition of the nucleophile to the remote alkyne in the cations [ 1 a–d ]⁺ is difficult to rationalise from the vinylidene form of the precursor and is much more satisfactorily explained from initial isomerisation to the quinoidal cumulene complexes [M(=C=C=C₆H₄=C=CH₂)(LL)Cp’]⁺ prior to attack at the more exposed, remote quaternary carbon. Thus, whilst representative acetylide complexes [Ru(C≡C-1,4-C₆H₄-C≡CH)(PPh₃)₂Cp] ( 4 a ) and [Ru(C≡C-1,4-C₆H₄-C≡CH)(dppe)Cp*] ( 4 b ) reacted with the relatively small electrophiles [CN]⁺ and [C₇H₇]⁺ at the β-carbon to give the expected vinylidene complexes, the bulky trityl ([CPh₃]⁺) electrophile reacted with [M(C≡C-1,4-C₆H₄-C≡CH)(LL)Cp’] [M(LL)Cp’=Ru(PPh₃)₂Cp ( 4 a ); Ru(dppe)Cp* ( 4 b ); Fe(dppe)Cp ( 4 c ); Fe(dppe)Cp* ( 4 d )] at the more exposed remote end of the carbon-rich ligand to give the putative quinoidal cumulene complexes [M{C=C=C₆H₄=C=C(H)CPh₃}(LL)Cp’]⁺, which were isolated as the water adducts [M{C≡C-1,4-C₆H₄-C(=O)CH₂CPh₃}(LL)Cp’] ( 6 a–d ). Evincing the scope of the formation of such extended cumulenes from ethynyl-substituted arylvinylene precursors, the rather reactive half-sandwich (5-ethynyl-2-thienyl)vinylidene complexes [M{C=C(H)-2,5-^cC₄H₂S-C≡CH}(LL)Cp’]BF₄ ([ 7 a – d ]BF₄ add water readily to give [M{C≡C-2,5-^cC₄H₂S-C(=O)CH₃}(LL)Cp’] ( 8 a – d )].     

Reactions of transition metal σ-acetylide complexes: IX. Preparation and properties of some cycloheptatrienylvinylidene complexes

Addition of [C₇H₇][PF₆] to iron, ruthenium or osmium alkynyl complexes has given eight cationic cycloheptatrienylvinylidene derivatives [M{C C(C₇H₇)R}(L)₂ (η-C₅H₅)][PF₆] (M = Fe, Ru or Os; R = Me, Pr, Ph or C₆F₅; L = PPh₃, L₂ = dppm or dppe; but not all combinations). With Fe(C₂Ph)(CO)₂(η-C₅H₅), only [Fe(CO)₂(thf)(η-C₅H₅)][PF₆] was obtained. Reactions of the new complexes are characterised by loss of the C₇H₇ group. The NMR spectra and FAB mass spectra are described in detail.     

Synthesis and reactions of cycloheptadienyl and cyclooctadienyl tungsten complexes: X-ray crystal structure of [W(CO)2(PPh3)2(η-C7H9)][BF4]

Protonation of the cycloheptatriene complex [W(CO)₃(η⁶-C₇H₈)] with H[BF₄] · Et₂O in CH₂Cl₂ affords the cycloheptadienyl system [W(CO)₃(η⁵-C₇H₉)][BF₄] (1). Complex 1 reacts with NaI to yield [WI(CO)₃(η⁵-C₇H₉)], which is a precursor to [W(CO)₂(NCMe)₃(η³-C₇H₉)][BF₄], albeit in very low yield. The dicarbonyl derivatives [W(CO)₂L₂(η⁵-C₇H₉)]⁺ (L₂=2PPh₃, 4, or dppm, 5) were obtained, respectively, by H[BF₄] · Et₂O protonation of [W(CO)₂(PPh₃)(η⁶-C₇H₈)] in the presence of PPh₃ and reaction of 1 with dppm. The X-ray crystal structure of 4 (as a 1/2 CH₂Cl₂ solvate) reveals that the two PPh₃ ligands are mutually trans and are located beneath the central dienyl carbon and the centre of the edge bridge. The first examples of cyclooctadienyl tungsten complexes [WBr(CO)₂(NCMe)₂(1-3-η:5,6-C₈H₁₁)] (6) and [WBr(CO)₂(NCMe)₂(1-3-η:4,5-C₈H₁₁)] (7) were synthesised by reaction of [W(CO)₃(NCR)₃] (R=Me or Prⁿ) with 3-Br-1,5-cod/6-Br-1,4-cod or 5-Br-1,3-cod/3-Br-1,4-cod (cod=cyclooctadiene), respectively. Complexes 6 and 7 are precursors to the pentahapto-bonded cyclooctadienyl tungsten species [W(CO)₂(dppm)(1-3:5,6-η-C₈H₁₁)][BF₄] and [W(CO)₂(dppe)(1-5-η-C₈H₁₁)][BF₄] · CH₂Cl₂.