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A mixture of the platinum(0) complex [Pt(P

A series of Au/FeOx/SBA-15 type materials were prepared by two methods: one conventional and one non-conventional: gold deposition-precipitation on FeOx/SBA-15 and bimetallic carbonyl cluster deposition on SBA-15, respectively. Both chemical physical characterization and catalytic activity tests in the complete combustion of methanol show that the new preparation method of Au/FeOx-supported catalysts leads to the anchoring of the Au by modifying the surface of SBA-15 with FeOx species. This effect results in a considerable improvement in catalyst performance as compared to the classic preparation by deposition-precipitation of Au on SBA-15 and FeOx/SBA-15.

The total oxidation of methanol and toluene, chosen as representative VOCs, was investigated over CeO2-supported Au/FeOx catalysts prepared utilizing the bimetallic carbonyl cluster salt [NEt4][AuFe4(CO)16]. Characterization data showed that the catalysts prepared by the reported method exhibit highly and homogeneously dispersed iron oxide species on the ceria support together with small gold nanoparticles, whose size increases on increasing the amount of gold/iron. Addition of iron oxide species did not substantially increase the methanol combustion activity of ceria, whereas the presence of the mixed gold and FeOx species has been found to strongly enhance the activity towards the total oxidation of methanol. In the case of the toluene combustion the addition of FeOx or FeOx/Au species caused a significant decrease in the activity of the bare CeO2. The above catalytic behavior was rationalized on the basis of different interactions occurring among gold, iron oxide and cerium oxide, which synergically affects both the reactivity of the surface oxygen and the capacity of the support to adsorb the organic reactant.

A straightforward and efficient synthetic route to novel Ru N-heterocyclic carbene (NHC) complexes by transmetallation of non-bulky silver NHC to ruthenium dicarbonyl tetraarylcyclopentadienone is described. The same procedure with sterically demanding NHC leads to unprecedented heterobimetallic Ru–Ag(NHC) complexes.

High yields of the ethoxo-α-aminoacidates of the general formula M(OEt)4[OC(O)CHRNHR'-κO,κN] (M = Nb, R = CH2Ph, R' = H, 2; R = CHMe2, R' = H, 3; R = CH2CHMe2, R' = H, 4; R = H, R' = Me, 5; R = CH2CH2SMe, R' = H, 6; M = Ta, R = CH2Ph, R' = H, 7; R = CH2CH2SMe, R' = H, 8) and M(OEt)4(OC(O)CH(CH2CH2CH2)NH-κO,κN) (M = Nb, 9; Ta, 10) have been obtained by the reaction of the l-enantiopure α-amino acid (or sarcosine) with a slight molar excess of M(OEt)5 (M = Nb, 1a; Ta, 1b) in a dichloromethane solution. The new complexes 2-10 have been fully characterized by spectroscopic and analytical methods and by X-ray diffraction for 2 and 7-9. Such X-ray structures are the first ones ever reported for niobium and tantalum coordination compounds containing an α-aminoacidato ligand. The early-late heterobimetallic derivative Ta(OEt)4[O2CCH(NH2)CH2CH2S(CH3)(AuCl)] (11) has been prepared by the reaction of 8 with a stoichiometric amount of Au(CO)Cl. The bulk polymerization of D,L-lactide initiated by complexes 2 and 7 gave a slightly heterotactic enchainment (Pr = 0.54 and 0.63, respectively), whereas complexes 1a and 1b formed fully atactic polylactide with P(r) ≈ 0.4.

Four Cu(I) complexes with general formulas [Cu((NN)-N-boolean AND)(2)][BF4] and [((PP)-P-boolean AND) Cu((NN)-N-boolean AND)][BF4] were prepared, where (NN)-N-boolean AND stands for 2-(2-tert-butyl-2H-tetrazol-5-yl)pyridine and (PP)-P-boolean AND is a chelating diphosphine, namely bis-(diphenylphosphino) methane (dppm), bis-(diphenylphosphino) ethane (dppe) or bis[2-(diphenylphosphino) phenyl] ether (POP). In an acetonitrile medium, the Electro-Spray Ionization Mass Spectrometry (ESI-MS) determination provided the preliminary evidence for the occurrence of the dppm-containing complex as a mixture of a cationic mononuclear [Cu((NN)-N-boolean AND)(dppm)](+) species and a bis-cationic dinuclear [Cu-2((NN)-N-boolean AND)(2)(dppm)(2)](2+)-type compound. Definitive evidence of peculiar structural features came from X-ray crystallography, which showed both the dppm-and, unexpectedly, the dppe-based heteroleptic compounds to crystallize as diphosphine-bridged Cu(I) dimers, unlike [Cu((NN)-N-boolean AND) 2](+) and [(POP) Cu( (NN)-N-boolean AND)]+ which are mononuclear species. In solutions of non-coordinating solvents, P-31 NMR studies at variable temperatures and dilution titrations confirmed that the dppm-based complex undergoes a monomer-dimer dynamic equilibrium, while the dppe-containing complex occurs as the bis-cationic dinuclear species, [Cu-2((NN)-N-boolean AND)(2)(dppe)(2)](2+), within a concentration range comprised between 10(-2) and 10(-4) M. Differences among heteroleptic complexes might be related to the smaller natural bite angle displayed by dppm and dppe phosphine ligands (72 and 85, respectively), with respect to that reported for POP (102). The electrochemical features of the new species have been investigated by cyclic voltammetry. Despite the irreversible and complicated redox behaviour, which is typical for copper complexes, the reductions have been attributed to the tetrazole ligand whereas the oxidations are characterized as Cu(I/II) processes with a substantial contribution from the (PP)-P-boolean AND-based ligands in the case of the heteroleptic species. All the four complexes are weakly or not luminescent in CH2Cl2 solution, but heteroleptic complexes are bright green luminophores in a solid matrix, with quantum yields as high as 45% (dppm complex) even at room temperature. This makes them potential candidates as cheap emitting materials for electroluminescent devices.

The diiron bridging vinyliminium complexes [Fe2{µ-η1-η3-C=;N(Me)2C(R')=C(R'')}(µ-CO)(CO)(Cp)2][SO3CF3] (R' = H, R''; = SiMe3, 3a; R' = H, R'' = Tol =4-MeC6H4, 3b; R' = Me, R'' = Me, 3c; R' = SPh, R'' = Me, 3d; R' = H, R'' = Fc = [Fe(C5H4)(Cp)], 6e) react with propargyl alcohol (HC≡CCH2OH), in refluxing toluene, affording the polysubstituted ferrocenes as mixtures of two isomeric forms: [1-NMe2-2-R'-3-R''-5-CH2OCH2C≡CH-Fc] (R' = H, R'' = SiMe3, 6a; R' = H, R'' = Tol, 6b; R' = Me, R'' = Me, 6c; R' = SPh, R'' = Me, 6d, R' = H, R'' = Fc, 6e) and [1-NMe2-2-R'-3-R''-4-CH2OCH2C≡CH-Fc] (R' = H, R'' = SiMe3, 7a; R' = H, R'' = Tol, 7b; R' = Me, R'' = Me, 7c; R' = SPh, R'' = Me, 7d) in overall yields of about 55–65%. Formation of the functionalized cyclopentadienyl in the ferrocene products takes place through the assembly of two propargyl units with the bridging vinyliminium ligand: one alkynol is incorporated by a [3 + 2] cycloaddition with the bridging C3 ligand; a second alkynol unit gives rise to a pendant chain through -OH substitution. Investigations show that the substitution step is catalyzed by the parent diiron complex itself or by a mononuclear iron fragment (likely the Fp+ complex). The pendant propargyl chain has been exploited to connect the ferrocene to other molecular fragments: in particular, the reaction of 6a with 4-biphenyl azide, by copper-catalyzed azide–alkyne cycloaddition (CuAAC), leads to the formation of the triazole-functionalized ferrocene [1-NMe2-2-CH2OCH2-N3(C6H4Ph)C2H-4-SiMe3-Fc] (12). Moreover, 6a reacts with Co2(CO)8, affording the complex [Co2{µ-η2-HC≡CR}(CO)6] (13), (HC≡CR = 6a), where the alkyne adopts a η2 coordination to a dicobalt hexacarbonyl fragment. The molecular structure of 7a has been determined by X-ray diffraction studies.

The diiron mu-vinyl complex [Fe2Cp2(CO)(2)(mu-CO){mu-eta(1):eta(2)-CH=CH(Ph)}]-[BF4], [1][BF4], reacted with CoCp2 affording selectively the C-C coupling product [Fe2Cp2(CO)(2)(mu-CO){mu-CHCH(Ph)}](2). 2. The cation [1](+) was regenerated from 2 in good yield by I-2-induced oxidative cleavage. The cation [1](+) underwent two sequential monoelectron reductions, the first one being an electrochemically reversible process that generated the radical species [Fe2Cp2(CO)(2)(mu-CO){mu-CHCH(Ph)}], [1](center dot). The latter was characterized by EPR spectroelectrochemistry. The structures of [1](+), [1](center dot) and 2 were optimized for the gas phase by DFT calculations. The reaction of [1] [BF4] with NEt3 in the presence of excess PhSSPh gave [Fe2Cp2(CO)(2)(mu-CO){mu-CHCH(Ph)(SPh)}], 3. The new compounds 2 and 3 were fully characterized by IR and NMR spectroscopy, elemental analysis, and X-ray diffraction studies.

Cyclophosphazenes (RNH)(6)P(3)N(3) 1 react with three and six equivalents of butyllithium in thf to give lithium complexes of tri- (2) and hexaanionic (3) phosphazenate ligands, respectively. A variety of lithium complexes 2 and 3 were prepared and structurally characterised. The degree of puckering of the (PN)(3) ring systems correlates with increasing ligand charge. The trianions solely exhibit the chair conformation; their deprotonated side groups are positioned at equatorial sites. This conformation ensures that the charge of the ligand is most effectively distributed and it also provides three distinct coordination sites for the three lithium ions. Complexes of the trianion can be monomeric or dimeric. Aryl-N(exo) derivatives tend to form monomers, while alkyl derivatives form dimeric sandwich complexes. Complexes of the hexaanion fall into two categories. Binary complexes, which contain the ligand and lithium ions, form dimers; the (PN)(3) ring in these complexes exhibit a chair conformation. Complexes which, in addition, contain small monodentate ions, such as chloride, fall into the second category; their ring systems adopt a boat conformation. (

The diiron complex [Fe2{μ-к1(O):η1(C):η3(C)–C(N(Me)(Xyl))C(H) C(Me)C(O)OMe}(μ-CO)(Cp)2] (2) has been obtained from the diiron bridging vinyliminium [Fe2{μ-η1:η3–C(Me) C(H)C N(Me)(Xyl)}(μ-CO)(CO)(Cp)2][SO3CF3] (1; Xyl = 2,5-C6H3Me2) upon treatment with NaH in the presence of CH2 C CMe2, followed by chromatography on alumina with MeOH as eluent. The reaction consists in the incorporation of a methylcarboxylate unit, assembled from CO and MeO−, into the bridging vinyliminium ligand. The resulting complex 2 exhibits a C4 fragment bridging the two iron centres through the carbonyl oxygen atom and the allylidene moiety. The X-ray molecular structure of 2 has been determined.

The total oxidation of methanol and toluene, chosen as representative VOCs, was investigated over CeO2- supported Au/FeOx catalysts prepared utilizing the bimetallic carbonyl cluster salt [NEt4][AuFe4(CO)16]. Characterization data showed that the catalysts prepared by the reported method exhibit highly and homogeneously dispersed iron oxide species on the ceria support together with small gold nanoparticles, whose size increases on increasing the amount of gold/iron. Addition of iron oxide species did not substantially increase the methanol combustion activity of ceria, whereas the presence of the mixed gold and FeOx species has been found to strongly enhance the activity towards the total oxidation of methanol. In the case of the toluene combustion the addition of FeOx or FeOx/Au species caused a significant decrease in the activity of the bare CeO2. The above catalytic behavior was rationalized on the basis of different interactions occurring among gold, iron oxide and cerium oxide, which synergically affects both the reactivity of the surface oxygen and the capacity of the support to adsorb the organic reactant.

The niobium N,N-dialkylcarbamates Nb(O(2)CNR(2))(n) [n = 5, R = Me, 1, Et, 2; n = 4, R = Et, 3; n = 3, R = Et, 4], in combination wits organoaluminum cocatalysts, were found to be active in the polymerization of ethylene. The effects of the main reaction parameters (solvent, ethylene pressure, time, temperature, cocatalyst, reactivator) on the polymerization reaction were investigated in detail. When 2 was used as precursor in combination with trimethylaluminum (TMA)-depleted MAO and 1,2-dichloroethane as reactivator, activity up to 110 kg(polyethylene) mol(Nb)(-1) h(-1) bar(-1) ascertained and linear, high molecular weight polyethylene was produced. The catalytic activities related to the different precursors increase along the series 2 > 1 > 3 > 4. The 1:1 reaction of 2 with Al(2)Et(3)Cl(3) proceeds via ligand exchange, giving the X-ray characterized mixed alkyl-carbamato derivative [Al(3)(mu-O(2)CNEt(2))(6)Et(2)]Cl (6), in admixture with presumable species containing niobium in lower oxidation state. The latter and not the former seem to be responsible for directing the polymerization process, according to the evidence that 6, produced by ligand exchange between Al(O(2)CNEt(2))(3) and AlEt(2)Cl, is not active under analogous experimental conditions.

The diiron bridging enaminoalkylidene complex [Fe2{μ-η1:η3-C(Fc)CHCH(NMe2)}(μ-CO)(CO)- (Cp)2] (2), containing a ferrocenyl group on the bridging ligand, reacts with HC≡CR, affording the corresponding 3-R-substituted 1,100-biferrocene (R =CPh2OH, 4a; R = Tol, 4b; R = CO2Me, 4c; R = CH2OH, 4d). In a related reaction, the μ-vinylaminoalkylidene complex [Fe2{μ-η1:η3-C- (NMe2)CHCH(CO2Me)}(μ-CO)(CO)(Cp)2] (1a), upon treatment with ethynylferrocene, leads to the formation of 2-NMe2-4-CO2Me-1,100-biferrocene (4f). Conversely, the μ-enaminoalkylidene complex [Fe2{μ-η1:η3-C(Tol)CHCH(NMe2)}(μ-CO)(CO)(Cp)2] (1b) reacts with ethynylferrocene, affording a mixture of monosubstituted biferrocene 4b and disubstituted 2-NMe2-4-Tol-1,100- biferrocene (4e), in comparable yields. Reaction of 2 with ethynylferrocene (HC≡CFc) leads to the formation of a mixture of 1,3-terferrocene (5a) and the 5-NMe2-substituted 1,3-terferrocene (5b). Investigation of the reactivity of the vinyliminium complex [Fe2{μ-η1:η3-C(Fc)CHCNMe2}(μ-CO)- (CO)(Cp)2][SO3CF3] (3) with HC≡CCPh2OH is also reported: the reaction affords selectively the 3-NMe2-4-R-disubstituted 1,100-biferrocene (6). The molecular structure of 5a has been determined by X-ray diffraction studies.

The reactions of vinyliminium complexes [Fe2{μ-η1:η3- C(R)=C(H)C=N(Me)(R)}(μ-CO)(CO)(Cp)2][SO3CF3] (R = Xyl, R = Me, 1a; R = Xyl, R = Tol, 1b; R = Xyl, R = COOMe, 1c; R = Me, R = Me, 1d; R = Me, R = nBu, 1e; R = p-MeOC6H4, R = Me, 1f; Tol = 4-C6H4Me, Xyl = 2,6-Me2C6H3) with CS2 and NaH resulted in the replacement of CH hydrogen (in the bridging frame) with CS2 to give the corresponding dithiocarboxylate- vinyliminium complexes [Fe2{μ-η1:η3-C(R)=C- (CS2)C=N(Me)(R)}(μ-CO)(CO)(Cp)2] (2a–2f). Analogously, 1a and 1d reacted with NaH and SCNPh to afford the complexes [Fe2{μ-η1:η3-C(R)=C{C(NPh)S}C=N(Me)(R)}(μ-CO)(CO)(Cp)2] (R = Xyl, R = Me, 3a; R = Me, R = Me, 3b), respectively. Complex 2b was methylated at the dithiocarboxylate group Introduction Organic molecules acting as bridging ligands are expected to exhibit reaction patterns different to those observed when the same species are uncoordinated or are bound to a single metal centre.[1] An example is offered by the chemistry of the bridging vinyliminium diiron complexes I (Scheme 1).[2] Indeed, bridging vinyliminium ligands undergo nucleophilic addition at the iminium carbon or the adjacent α-carbon position[3] instead of the 1,4-conjugated addition normally observed in α,β-unsaturated iminium species.[4] Another unique feature of μ-vinyliminium ligands is the activation of α-C–H (C2–H in Scheme 1), which does not occur in uncoordinated conjugated iminium species.[5] The deprotonation of μ-vinyliminium ligands has been exploited to introduce a variety of substituents and functionalities into the bridging frame, as shown in Scheme 1. The carbon atoms in the bridging chain have been numbered as shown in Scheme 1 to make clearer the discussions presented hereafter. [a] Dipartimento di Chimica e Chimica Industriale, Università di Pisa, via Risorgimento 35, 56126 Pisa, Italy [b] Dipartimento di Chimica Fisica e Inorganica, Università di Bologna, Viale Risorgimento 4, 40136 Bologna, Italy E-mail: valerio.zanotti@unibo.it © 2011 Wiley-VCH Verlag 1260 GmbH & Co. KGaA, Weinheim Eur. J. Inorg. Chem. 2011, 1260–1268 upon treatment with CH3SO3CF3 to yield [Fe2{μ-η1:η3- C(R)=C(CS2Me)C=N(Me)(Xyl)}(μ-CO)(CO)(Cp)2][SO3CF3] (4a). Likewise, the zwitterionic complexes 2d–f underwent addition of the metal fragment [Fe(CO)2Cp]+ at the dithiocarboxylate group to yield the corresponding triiron complexes [Fe2{μ-η1:η3-C(R)=C(CS2Fp)C=N(Me)(R)}(μ-CO)(CO)(Cp)2]- [SO3CF3] [R = R = Me, 4b; R = Me, R = nBu, 4c; R = p- MeOC6H4, R = Me, 4d; Fp = Fe(CO)2Cp]. In a related reaction with [Pd(CH3CN)2Cl2], 2a binded to Pd through the dithiocarboxylate group as chelating ligand to afford the complex [PdCl2{κ2-(S,S)-2a}] (5). The X-ray structures of 2b, 3a and 4d have been determined.

The reaction of [Ni 10 C 2 (CO) 15 ] 2- in thf with a large excess of CdCl 2 ·2.5H 2 O (8-15 equiv.) resulted in the formation of the new carbonyl octacarbide clusters [H 5-n Ni 36 C 8 (CO) 36 -(Cd 2 Cl 3 )] n- (n = 3-5), which undergo partial CO replacement to give [Ni 36-y C 8 (CO) 34-y (MeCN) 3 (Cd 2 Cl 3 )] 3- (y = 0-2) after a prolonged time in MeCN. Treatment of the former with an excess of NaOH afforded the larger [H 7-n Ni 42+y C 8 (CO) 44+y -(CdCl)] n- (n = 6, 7 ; y = 0, 1) octacarbides. Their structures (as well as those of the analogous Br-containing clusters) have been fully elucidated by single-crystal X-ray analysis of their [Me 4 N] 5 [Ni 36 C 8 (CO) 36 (Cd 2 Cl 3 )]·(7-2y)MeCN·yC 6 H 14 (y = 0.40), [Me 4 N] 3 [Ni 36-y C 8 (CO) 34-y (MeCN) 3 (Cd 2 Cl 3 )]·5MeCN (y = 0.61), [Me 4 N] 7 [Ni 42+y C 8 (CO) 44+y (CdCl)]·(5-y)MeCN (y = 0.19) and [Me 4 N] 6 [HNi 42+y C 8 (CO) 44+y (CdBr)]·(6-y)MeCN (y = 0.19) salts, which feature highly distorted metal cages (due to the inclusion of several carbide atoms), and the presence of partially vacant capping Ni(CO) fragments. This aspect, together with the fact that all these species undergo several protonation-deprotonation equilibria in solution as well as reversible redox processes under electrochemical control, indicates that a detailed description of molecular species containing a few dozen metal atoms might be sometimes rather troublesome and non-trivial. A complete elucidation of these systems can be achieved only by combining structural, chemical, spectroscopic, electrochemical and spectroelectrochemical studies.

The synthesis of a novel class of alcohol- and ether-functionalized indenyl ligands, focusing on the haptotropic rearrangements of the hybrid O-indenyl rhenium species, is herein described. η1- Indx OMeRe(CO)5 (12x) and η3-IndxOMeRe(CO)4 (13x, x=a, d) [IndaOMe=C9H6CH2CH(Me)OMe, 1a; Indd OMe=C9H6CH(CH2)3CHOMe, 1da] are examples of σ and allylic intermediates in the Cp substitution. The tuning of stereoelectronic effects of the functionalized alkyl chain or the coordinating solvent (MeCN, THF) allows the study of the relative stabilities of the intercepted solvento species η5-Indb OMeRe(CO)2(NCMe), 14b, η5-Indc OMeRe(CO)2(THF), 15c, or the chelate [η5:k1-OIndb, c ORe(CO)2], 16b,c {Indb OMe=[C9H6CH2CH(Ph)OMe]-, 4b; Indc OMe=[C9H6CH(Ph)CH2OMe]-, 4c}. DFT calculations reported on some of the IndO systems have been compared with those of smaller (CpO) 5a or larger (Flua O) 10a congeners, confirming the experimental findings. As peculiar examples of the underrepresented low-valent rhenium alkoxy species, the isolation of k1-O-HIndxORe(CO)5 [x=a, b] is also reported

Reactions of the vinylalkylidene complexes [Fe2{μ- η1:η3-CRCHCH(NMe2)}(μ-CO)(CO)(Cp) 2](R) SiMe3, 1a; Tol, 1b; CO2Me, 1c, Tol) 4-MeC6H4) with HC t CR′ (R′) CPh 2OH, CO2Me, Ph) lead to the formation of a mixture of 1,3-disubstituted ferrocenes [1-R-3-R′-Fc] (5, 7, 9, 11) and 1,2,4-trisubstituted ferrocenes [1-NMe2-2-R′-4-R-Fc] (4, 6, 8, 10)(R) SiMe3, R′) CPh2OH, 4 and 5; R) SiMe 3, R′) CO2Me, 6 and 7; R) SiMe3, R′) Ph, 8 and 9; R) Tol, R′) CPh2OH, 10 and 11). The polysubstituted Cp ring of the ferrocenyl products results from the cycloaddition of the alkyne with the bridging vinylalkylidene ligand and involves the cleavage of one of the two substituents (H or NMe2) on the vinyl moiety, as well as of the Fe - Fe bond. The cycloaddition reaction has been extended to a variety of bridging vinylalkylidene diiron complexes with different substituents and functionalities on the C3 bridging ligand, and to different alkynes. Thus, the vinylalkylidene complex 1b reacts with HC t CPh, yielding a mixture of four different ferrocenes, due to the absence of regioselectivity in the alkyne cycloaddition: [1-NMe2-2-Ph-4-Tol-Fc] (12), [1-Tol-3-Ph-Fc] (13), [1-NMe2-3-Ph-4-Tol-Fc] (14), and [1-Tol-2-Ph-Fc] (15). Conversely, the reactions with symmetric alkynes do not produce regioisomers: treatment of 1b and 1c with R′ C t CR′ (R′) Et, Ph) affords a mixture of 1,2,3-trisubstituted ferrocenes [1-R-2-R′-3-R′-Fc] (17, 19, 21, 23) and tetrasubstituted ferrocenes [1-NMe2-2-R′-3-R′-4-R-Fc] (16, 18, 20, 22)(R) SiMe 3, R′) Et, 16 and 17; R) Tol, R′) Et, 18 and 19; R) Tol, R′) Ph, 20 and 21; R) CO2Me, R′) Ph, 22 and 23). Likewise, the vinylalkylidene complexes [Fe2{μ-η1: η3-C(X)CHCH(R)}(μ-CO)(CO)(Cp)2](R) CO 2Me, X) NMe2, 2a; R) CN, X) NMe2, 2b; R) CO2Me, X) SMe, 3a; R) CN, X) SMe, 3b) react with alkynes HC t CR′ (R′) Tol, Ph), yielding a mixture of trisubstituted ferrocenes [1-X-2-R′-4-R-Fc] (24, 26, 28) and [1-X-3-R′-4-R-Fc] (25, 27, 29)(X) NMe2, R) CO2Me, R′) Tol, 24 and 25; X) NMe 2, R) CN, R′) Tol, 26 and 27; X) SMe, R) CO2Me, R′) Ph, 28 and 29). Finally, the reactions of 2a and 3b with PhC t CPh afford the tetrasubstituted ferrocenes 22 and [1-SMe-2-Ph-3-Ph-4-CN-Fc] (30), respectively. The crystal structures of 4 and 11 have been determined by X-ray diffraction studies.

The zwitterionic vinyliminium complex [Fe2{μ-η1:η3-C(R′) C(S)C N(Me)(Xyl)}(μ-CO)(CO)(Cp)2] (2a) (R′ = p-Me-C6H4 (Tol), Xyl = 2,6-Me2C6H3) undergoes electrophilic addition at the S atom by HSO3CF3, MeSO3CF3, SiMe3Cl, BrCH2Ph, ICH2CH CH2 affording the complexes [Fe2{μ-η1:η3-C(Tol) C(SX)C N(Me)(Xyl)}(μ-CO)(CO)(Cp)2][Y] (X = H, Y = SO3CF3, 4a; X = Me, Y = SO3CF3, 4b; X = SiMe3, Y = Cl, 4c; X = CH2Ph, Y = Br, 4d; X = CH2CH CH2, Y = I, 4e). Compound 2a and the corresponding vinyliminium complexes 2b and 2c (R′ = CH2OH, 2b; R′ = Me, 2c) react also with etherated BF3 leading to the formation of the corresponding S-adducts [Fe2{μ-η1:η3-C(R′) C(SBF3)C N(Me)(Xyl)}(μ-CO)(CO)(Cp)2] (R′ = Tol, 5a; R′ = CH2OH, 5b; R′ = Me, 5c). In analogous reactions, the zwitterionic vinyliminium complexes undergo S-metalation upon treatment with in situ generated [Fp]+[SO3CF3]− [Fp = Fe(CO)2(Cp)], leading to the formation of [Fe2{μ-η1:η3-C(R′) C(S–Fp)C N(Me)(Xyl)}(μ-CO)(CO)(Cp)2][SO3CF3](R′ = CH2OH, 6a; R′ = Me, 6b; R′ = Bun, 6c). Similarly, zwitterionic vinyliminium containing Se in the place of S also undergo Se-electrophilic addition. Thus, the complexes [Fe2{μ-η1:η3-C(R′) C(SeX)C N(Me)(R)}(μ-CO)(CO)(Cp)2][SO3CF3] (R = X = Me, R′ = Tol, 7a; R = Xyl, R′ = Me, X = Fp+, 7b) are obtained upon treatment of the neutral zwitterionic precursors with MeSO3CF3 and [Fp][SO3CF3], respectively. Alkylation at the S or Se atom of the bridging ligand is also accomplished by CH2Cl2, used as solvent, although the reaction is slower compared to more efficient alkylating reagents. The complexes formed by this route are [Fe2{μ-η1:η3-C(R′) C(E-CH2Cl)C N(Me)(R)}(μ-CO)(CO)(Cp)2][X] [E = S, R = Xyl, R′ = Tol, X = Cl, 8a; E = S, R = Xyl, R′ = Me, X = Cl, 8b; E = Se, R = R′ = Me, X = BPh4, 8c]. Finally, treatment of the zwitterionic vinyliminium complexes with I2 results in the oxidative coupling with formation of S–S (disulfide) or Se–Se (diselenide) bond. The reactions, performed in the presence of NaBPh4 afford the tetranuclear complexes [Fe2{μ-η1:η3-C(R′) C(E)C N(Me)(R)}(μ-CO)(CO)(Cp)2]2[BPh4]2 [R = Xyl, R′ = CH2OH, E = S, 9a; R = Xyl, R′ = Me, E = S, 9b; R = Xyl, R′ = Bun, E = S, 9c; R = Xyl, R′ = Me, E = Se, 9d; R = Me, R′ = Bun, E = Se, 9e]. The molecular structures of 4a, 8c and 9e have been determined by X-ray diffraction studies.

The reactions of niobium and tantalum pentahalides, MX5, with dialkylureas (tetramethyl- and tetraethylurea, TMU and TEU, respectively), amides (N,N,dimethylformamide, DMF, N,N-diethylformamide, DEF, N-phenylacetamide, PhA), and P=O-containing compounds (triphenylphosphane oxide, TPPO, and trimethyl phosphate, TMP) are not dependent on the reactant to metal molar ratio, and afford hexacoordinate complexes of the general formula MX5(L). The only exception is given by the reaction of TaBr5 with TMU, which proceeds by bromide migration from one metal center to another, and provides the ionic adduct [TaBr4(TMU)2][TaBr6]. Hydrolysis of TaCl5(TMP), due to adventitious water, has yielded the dinuclear species Ta2(μ-O)Cl8(TMP)2. All compounds have been fully characterized in solution, and X-ray crystal structures have been determined for NbCl5(TEU), NbCl5(DMF), TaCl5(DMF), TaCl5(PhA), TaBr5(PhA), TaCl5(TPPO), [TaBr4(TMU)2][TaBr6], and Ta2(μ-O)Cl8(TMP)2. No evidence for formation of M=O bonds due to oxygen atom transfer from the ligand to the metal has been observed in any case. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

The progressive addition of anhydrous pyridine, (py), to a solution of [Rh(4)(CO)(12)] in CH(2)Cl(2) under CO, even at low temperature, results in immediate disproportionation to give cis-[Rh(CO)(2)py(2)][Rh(5)(CO)(15)]; further addition of pyridine results in the progressive replacement of CO's by py on the same apical rhodium in [Rh(5)(CO)(15)](-) to give cis-[Rh(CO)(2)py(2)][Rh(5)(CO)(15-x)py(x)] (x = 1, 2). The analogous reactions with 2,2'-bipyridine (bipy) give only [Rh(CO)(2)bipy][Rh(5)(CO)(13)bipy]. IR and low temperature, multinuclear NMR measurements have been used to establish the structures of all the above anions and the structures of [Rh(5)(CO)(13)(bipy)](-) and [Rh(5)(CO)(13)py(2)](-) are subtly different. Under N(2), [Rh(4)(CO)(12)] reacts with py to give [Rh(6)(CO)(16-y)py(y)] (y = 1, 2).

The complexes MX5(THF) (M = Nb, X = Cl, 2a; M = Ta, X = F, 2c, X = Cl, 2d) and [MX4(THF){O(CH2)4O(CH2)3CH2)}][MX6] (M = Nb, X = Cl, 3a; M = Ta, X = Cl, 3d, X = Br, 3e, X = I, 3f) result from reactions of MX5 with 0.5 and 1.5 equiv of THF, respectively. Compounds 3 contain the unprecedented 4-(tetrahydrofuran-1-ium)-butan-1-oxo ligand and are likely to play a role in the course of THF polymerization catalyzed by MX5. The addition of L (L = 2,5-dimethyltetrahydrofuran, tetrahydropyran, 1,4-dioxane) to MX5 results in the formation of the hexacoordinated complexes MX5(L). The molecular structures of 2d, 3d, and NbCl5(dioxane), 6a, have been ascertained by X-ray diffraction studies.

Phosphazenes (RNH)6P3N3 (R = n-propyl, isobutyl, isopropyl, cyclohexyl, tert-butyl, benzyl) are readily alkylated at ring N sites by alkyl halides forming N-alkyl phosphazenium cations. Alkylation of two ring N sites occurred after prolonged heating in the presence of methyl iodide or immediately at room temperature with methyl triflate yielding N,N'-dimethyl phosphazenium dications. Geminal dichloro derivatives Cl2(RNH)4P3N3 are methylated by methyl iodide at the ring N site adjacent to both P centers carrying four RNH groups. X-ray crystal structures showed that the alkylation of ring N sites leads to substantial elongation of the associated P-N bonds. Both N-alkyl and N,N'-dialkyl phosphazenium salts form complex supramolecular networks in the solid state via NH...X interactions. Systems carrying less-bulky RNH groups show additional NH...N bonds between N-alkyl phosphazenium ions. N-Alkyl phosphazenium halides form complexes with silver ions upon treatment with silver nitrate. Depending on the steric demand of RNH substituents, either one or both of the vacant ring N sites engage in coordination to silver ions. Treatment of (RNH)6P3N3 (R = isopropyl) with acetyl chloride and benzoyl chloride, respectively, yielded N-acyl phosphazenium ions. X-ray crystal structures revealed that elongation of P-N bonds adjacent to the acylated ring N site is more pronounced than it is in the case of N-alkylated species. Salts containing N-alkyl phosphazenium ions are stable toward water and other mild nucleophiles, while N,N'-dialkyl and N-acyl phosphazenium salts are readily hydrolyzed. The reaction of (RNH)6P3N3 with bromoacetic acid led to N-alkylation at one ring N site in addition to formation of an amide via condensation of an adjacent RNH substituent with the carboxylic acid group. The resulting bromide salt contains mono cations of composition (RNH)5P3N3CH2CONR in which a CH2-C(O) unit is embedded between a ring N and an exocyclic N site of the phosphazene.

The vinyliminium complexes [M2{μ-η1:η3-Cγ(R‘)CβHCαN(Me)(R)}(μ-CO)(CO)(Cp)2][SO3CF3] (1a−f) react with ethyl diazoacetate in the presence of NaH, affording the azine−bis(alkylidene) [M2{μ-η1:η2-Cγ(R‘)Cβ{NNCδ(COOMe)H}CαN(Me)(R)}(μ-CO)(CO)(Cp)2] (M = Fe, R = 2,6-Me2C6H3 (Xyl), R‘ = Me (2a), p-C6H4Me (Tol) (2b), CO2Me (2c), Bun (2d); M = Fe, R = R‘ = Me (2e); M = Ru, R = Xyl, R‘ = Me (2f)) in 70÷77% yields. Analogous reactions with N2CPh2 lead to the formation of [Fe2{μ-η1:η2-Cγ(R‘)Cβ(NNCδPh2)CαN(Me)(Xyl)}(μ-CO)(CO)(Cp)2] (R‘ = Me (3a), COOMe (3b)). The azine−bis(alkylidene) ligand easily undergoes electrophilic addition, affording the cationic hydrazone−vinyliminium complexes [Fe2{μ-η1:η3-Cγ(R‘)Cβ{N(E)NCδ(R‘ ‘)(R‘ ‘‘)}CαN(Me)(Xyl)}(μ-CO)(CO)(Cp)2]+ (R‘ = Me, R‘ ‘ = CO2Et, R‘ ‘‘ = E = H, 4a; R‘ = Me, R‘ ‘ = COOEt, R‘ ‘‘ = H, E = Me, 4b; R‘ = Bun, R‘ ‘ = COOEt, R‘ ‘‘ = H, E = Me, 4c; R‘ = Me, R‘ ‘ = R‘ ‘‘ = Ph, E = Me, 4d). Reactions of 4b,d with NaBH4 result in the addition of hydride at the Cα of the vinylim...

The bridging diiron thiocarbyne complex [Fe2{μ-CS(Me)}(μ-CO)(CO)2(Cp)2]ISO 3 CF 3 ] (1) reacts with activated olefins (methyl acrylate, acrylonitrile, styrene, diethyl maleate), in the presence of Me 3 NO and NaH, to give the corresponding μ-allylidene complexes [Fe 2 {μ-η 1 :η 3 -C α (SMe)C β (R')C γ (H)(R")} (μ-CO)(CO)(Cp) 2 ] (R" = CO 2 Me, R'= H, 3a; R" = CN, R'= H, 3b; R" = C 6 H 5 , R'= H, 3c; R" = R' = CO 2 Et, 3d). The coupling reaction of olefin with thiocarbyne is regio- and stereospecific, leading to the formation of only one isomer. C-C bond formation occurs between the less substituted alkene carbon and the thiocarbyne. Moreover, olefinic hydrogens of the bridging ligands are mutually trans. The reactions of 3a-b with MeSO 3 CF 3 result, selectively, in the formation of the cationic μ-sulphonium allylidene complexes [Fe 2 [μ-η 1 :η 3 -C α (SMe 2 )C β (H)C γ (H)(R)}(μ-CO)(CO)(Cp)2][SΟ 3 CF 3 ] (R = CΟ 2 Me, 4a; R = CN, 4b). Compound 4a undergoes displacement of the SMe 2 group by nucleophiles such as NaBH 4 , NBu 4 CN and NaOMe, affording the complexes [Fe 2 ( μ-η 1 :η 3 -C α (R)C β (H)C γ H)(CΟ 2 -Me)}(μ-(CO)(Cp) 2 ] (R = H, 5a; R = CN, 5b; R = OMe, 5c), respectively. The molecular structures of 3a and 5a have been determined by X-ray diffraction studies.

The diiron vinyliminium complexes [Fe2{μ-η1:η3-C(R‘)CHCN(Me)(R)}(μ-CO)(CO)(Cp)2][SO3CF3] [R = Xyl, R‘ = Me, 1a; R = Xyl, R‘ = Tol, 1b; R = Xyl, R‘ = CO2Me, 1c; R = Xyl, R‘ = CH2OH, 1d; R = Xyl, R‘ ...

Primary alkynes R′C CH [R′ = Me3Si, Tol, CH2OH, CO2Me, (CH2)4C CH, Me] insert into the metal–carbon bond of diruthenium μ-aminocarbynes [Ru2{μ-CN(Me)(R)}(μ-CO)(CO)(MeCN)(Cp)2][SO3CF3] [R = 2,6-Me2C6H3 (Xyl), 1a; CH2Ph (Bz), 1b; Me, 1c] to give the vinyliminium complexes [Ru2{μ-η1:η3-C(R′) CHC N(Me)(R)}(μ-CO)(CO)(Cp)2][SO3CF3] [R = Xyl, R′ = Me3Si, 2a; R = Bz, R′ = Me3Si, 2b; R = Me, R′ = Me3Si, 2c; R = Xyl, R′ = Tol, 3a; R = Bz, R′ = Tol, 3b; R = Bz, R′ = CH2OH, 4; R = Bz, R′ = CO2Me, 5a; R = Me, R′ = CO2Me, 5b; R = Xyl, R′ = (CH2)4C CH, 6; R = Xyl, R′ = Me, 7a; R = Bz, R′ = Me, 7b; R = Me, R′ = Me, 7c]. The related compound [Ru2{μ-η1:η3-C[C(Me) CH2] CHC N(Me)(Xyl)}(μ-CO)(CO)(Cp)2][SO3CF3], (9) is better prepared by reacting [Ru2{μ-CN(Me)(Xyl)}(μ-CO)(CO)(Cl)(Cp)2] (8) with AgSO3CF3 in the presence of HC CC(Me) CH2 in CH2Cl2 at low temperature.In a similar way, also secondary alkynes can be inserted to give the new complexes [Ru2{μ-η1:η3-C(R′) C(R′)C N(Me)(R)}(μ-CO)(CO)(Cp)2][SO3CF3] (R = Bz, R′ = CO2Me, 11; R = Xyl, R′ = Et, 12a; R = Bz, R′ = Et, 12b; R = Xyl, R′ = Me, 13). The reactions of 2–7, 9, 11–13 with hydrides (i.e., NaBH4, NaH) have been also studied, affording μ-vinylalkylidene complexes [Ru2{μ-η1:η3-C(R′)C(R″) C(H)N(Me)(R)}(μ-CO)(CO)(Cp)2] (R = Bz, R′ = Me3Si, R″ = H, 14a; R = Me, R′ = Me3Si, R″ = H, 14b; R = Bz, R′ = Tol, R″ = H, 15; R = Bz, R′ = R″ = Et, 16), bis-alkylidene complexes [Ru2{μ-η1:η2-C(R′)C(H)(R″)CN(Me)(Xyl)}(μ-CO)(CO)(Cp)2] (R′ = Me3Si, R″ = H, 17; R′ = R″ = Et, 18), acetylide compounds [Ru2{μ-CN(Me)(R)}(μ-CO)(CO)(C CR′)(Cp)2] (R = Xyl, R′ = Tol, 19; R = Bz, R′ = Me3Si, 20; R = Xyl, R′ = Me, 21) or the tetranuclear species [Ru2{μ-η1:η2-C(Me)CCN(Me)(Bz)}(μ-CO)(CO)(Cp)2]2 (23) depending on the properties of the hydride and the substituents on the complex. Chromatography of 21 on alumina results in its conversion into [Ru2{μ-η3:η1-C[N(Me)(Xyl)]C(H)C CH2}(μ-CO)(CO)(Cp)2] (22). The crystal structures of 2a[CF3SO3] · 0.5CH2Cl2, 12a[CF3SO3] and 22 have been determined by X-ray diffraction studies.

The vinyliminium complexes [Fe2{μ-η1:η3-C(R′) C(R′)C N(Me)(R)}(μ-CO)(CO)(Cp)2][SO3CF3] (R = Me, R′ = Et, 1a; R = Me, R′ = Ph, 1b; R = R′ = Me, 1c; R = Xyl, R′ = Me, 1d; R = Xyl, R′ = Et, 1e; R = Xyl, R′ = Ph, 1f; Xyl = 2,6-Me2C6H3), react with MeLi affording the corresponding μ-vinylalkylidene complexes [Fe2{μ-η1:η3-C(R′)C(R′) CHN(Me)(R)}(μ-CO)(CO)(Cp){C5H4(Me)}] (2a–f). The formation of 2a–f is believed to proceed via nucleophilic attack at the Cp ligand, followed by hydrogen migration from the resulting cyclopentadiene to the iminium carbon. Similarly, the complex [Fe2{μ-η1:η3-C(Ph) C(Ph)C N(Me)(Xyl)}(μ-CO)(CO)(Cp)2][SO3CF3] reacts with PhLi to give [Fe2{μ-η1:η3-C(Ph)C(Ph) CHN(Me)(Xyl)}(μ-CO)(CO)(Cp){C5H4(Ph)}] (4). Treatment of 2a with CF3SO3CH3 results in methylation of the nitrogen, yielding the complex [Fe2{μ-η1:η3-C(Et)C(Et)CH(NMe3)}(μ-CO)(CO)(Cp){C5H4(Me)}][CF3SO3] (5). Analogously, the μ-vinylalkylidene complexes [Fe2{μ-η1:η3-C(R′)C(R″) CHN(Me)(R)}(μ-CO)(CO)(Cp)2], (R = Me, R′ = Tol, R″ = H, 3a; R = Me, R′ = SiMe3, R″ = H, 3b; R = Me, R′ = R″ = Et, 3c; R = Me, R′ = R″ = Ph, 3d; R = Bz, R′ = Tol, R″ = H, 3e; R = Bz, R′ = SiMe3, R″ = H, 3f; R = Bz, R′ = COOMe, R″ = H, 3g; R = Bz, R′ = R″ = COOMe, 3h; R = Bz, R′ = R″ = Me, 3i; Bz = CH2Ph), react with CF3SO3CH3 to give the corresponding ammonium-functionalized μ-allylidene complexes [Fe2{μ-η1:η3-C(R′)C(R″)CH(NMe2R)}(μ-CO)(CO)(Cp)2][CF3SO3] (6a–i). The molecular structures of 5 and 6c have been elucidated by X-ray diffraction studies. Finally, protonation of [Fe2{μ-η1:η3-C(Et)C(Et) CH(NMe2)}(μ-CO)(CO)(Cp)2] (3c), with HBF4, affords the complex [Fe2{μ-η1:η3-C(Et)C(Et)CH(NHMe2)}(μ-CO)(CO)(Cp)2]][BF4] (7).

The diiron complexes [Fe(Cp)(CO){μ-η 2 :η 2 -C[N(Me)(R)]N C(C 6 H 3 R′)C CH(Tol)}Fe(Cp)(CO)] (R = Xyl, R′ = H, 3a ; R = Xyl, R′ = Br, 3b ; R = Xyl, R′ = OMe, 3c ; R = Xyl, R′ = CO 2 Me, 3d ; R = Xyl, R′ = CF 3 , 3e ; R = Me, R′ = H, 3f ; R = Me, R′ = CF 3 , 3g ) are obtained in good yields from the reaction of [Fe 2 {μ-CN(Me)(R)}(μ-CO)(CO)( p -NCC 6 H 4 R′)(Cp) 2 ] + (R = Xyl, R′ = H, 2a ; R = Xyl, R′ = Br, 2b ; R = Xyl, R′ = OMe, 2c ; R = Xyl, R′ = CO 2 Me, 2 d; R = Xyl, R′ = CF 3 , 2e ; R = Me, R′ = H, 2f; R = Me, R′ = CF 3 , 2g ) with TolC CLi. The formation of 3 involves addition of the acetylide at the coordinated nitrile and C–N coupling with the bridging aminocarbyne together with orthometallation of the p -substituted aromatic ring and breaking of the Fe–Fe bond. Complexes 3a – e which contain the N(Me)(Xyl) group exist in solution as mixtures of the E - trans and Z - trans isomers, whereas the compounds 3f,g , which posses an exocyclic NMe 2 group, exist only in the Z-cis form. The crystal structures of Z - trans - 3b , E - trans - 3c , Z - trans - 3e and Z - cis - 3g have been determined by X-ray diffraction experiments.

One of the distinct features of metal-tetrazolate complexes is the possibility of performing electrophilic additions onto the imine-type nitrogens of the coordinated five-membered ring. These reactions, in particular, provide a useful tool for varying the main structural and electronic properties of the starting tetrazolate complexes. In this paper, we demonstrate how the use of a simple protonation-deprotonation protocol enables us to reversibly change, to a significant extent, the light-emission output and performance of a series of Re(I)-tetrazolate-based phosphors of the general formulation fac-[Re(N(∧)N)(CO)3L], where N(∧)N denotes diimine-type ligands such as 2,2'-bipyridine (bpy) or 1,10-phenanthroline (phen) and L represents a series of different 5-aryl tetrazolates. Indeed, upon addition of triflic acid to these neutral Re(I) complexes, a consistent blue shift (Δλmax ca. 50 nm) of the emission maximum is observed and the protonated species also display increased quantum yield values (4-13 times greater than the starting compounds) and longer decay lifetimes. This alteration can be reversed to the initial condition by further treating the protonated Re(I) complex with a base such as triethylamine. Interestingly, the reversible modulation of luminescent features by the same protonation-deprotonation mechanism appears as a quite general characteristic of photoactive metal tetrazolate complexes, even for compounds in which the 2-pyridyl tetrazolate ligands coordinate the metal center with a bidentate mode, such as the corresponding Ir(III) cyclometalates [Ir(C(∧)N)2L] and the Ru(II) polypyridyl derivatives [Ru(bpy)2L](+). In these cases, the protonation of the starting materials leads to red-shifted and more intense emissions for the Ir(III) complexes, while almost complete quenching is observed in the case of the Ru(II) analogues.

N,N-Diethylcarbamates [NbE(O2CNEt2)3] (E = O, S) have been prepared in high yields by treating NbOCl3 or [NbSCl3(CH3CN)2] with CO2/NHEt2 in toluene at approximately -10 degrees C. The products were characterized by spectroscopic techniques, elemental analysis and X-ray diffractometry in the case of [NbO(O2CNEt2)3]. The molecular structure of the latter consists of a niobium centre coordinated to the oxido moiety and six O atoms belonging to bridging and bidentate carbamates, in a slightly distorted pentagonal-bipyramidal arrangement. The structures of both [NbE(O2CNEt2)3] compounds were reproduced by DFT calculations, which show substantial similarity despite the different nature of the chalcogen atoms.

WCl6, 1, reacted with two equivalents of HC(O)NR2 (R = Me, Et) in CH2Cl2 to afford the W((VI)) oxo-derivatives WOCl4(OCHNR2) (R = Me, 2a; R = Et, 2b) as main products. The hexachlorotungstate(V) salts [{O-C-N(Me)CH2CH2CH2}(2)(mu-H)][WCl6], 3, and [PhNHC(Me)N(Ph)C(O)Me][WCl6], 4, were isolated in moderate yields from the 1 : 2 molar reactions of 1 with N-methyl-2-pyrrolidone (in CH2Cl2) and acetanilide (in CDCl3), respectively. The additions of two equivalents of ketones/aldehydes to 1/CH2Cl2 yielded the complexes WOCl4[OC(R)(R')] (R = Me, R' = Ph, 5a; R = R' = Ph, 5b; R = R' = Me, 5c; R = R' = Et, 5d; R = H, R' = 2-Me-C6H4, 5e) and equimolar amounts of C(R)(R')Cl-2. Analogously, WOCl3[kappa(2)-{1,2-C6H4(O)(CHO)}], 5f, and 1,2-C6H4(OH)(CHCl2) were obtained from 1 and salicylaldehyde. The 1 : 1 reaction of 1 with acetone in CH2Cl2 resulted in the clean formation of WOCl4 and 2,2-dichloropropane. Compounds 5a, b, f were isolated as crystalline solids, whereas 5c, d, e could be detected by solution NMR only. The interaction of 1/CH2Cl2 with isatin, in a 1 : 1 molar ratio, revealed to be a new, convenient route for the synthesis of 3,3-dichloro-2,3-dihydro-1H-indol-2-one, 6. The 1 : 1 reactions of 1 with R'OCH(R)CO2Me (R = H, R' = Me; R = Me, R' = H) in a chlorinated solvent afforded the tungsten(V) adducts WCl4[kappa(2)-OCH(R)(COMe)-Me-2] (R = H, 7a; R = Me, 7b). 1/CH2Cl2 reacted sluggishly with equimolar quantities of trans-(CO2Et)CH=CH(CO2Et) and CH2(CO2Me)(2) to give, respectively, the W(IV) derivatives WCl4[kappa(2)-CH2(CO2Me)(2)], 8a, and [WCl4-kappa(2)-{trans-(CO2Et)CH-CH (CO2Et)}](n), 8b, in about 70% yields. The molecular structures of 2a, 3, 4, 5a, 5f, 7a and 7b were ascertained by X-ray diffraction studies.