Μ-vinylidene Complexes Research Articles

Trinuclear ReFePt clusters with a μ3-phenylvinylidene ligand: synthetic approaches, rearrangement of vinylidene, and redox-induced transformations.

A series of trinuclear μ3-vinylidene ReFePt clusters were synthesized by the application of two approaches: (i) reactions of the binuclear RePt μ-vinylidene complexes with Fe2(CO)9; (ii) ligand substitution or exchange reactions at the Pt atom in the synthesized ReFePt clusters. The molecular structures of CpReFePt(μ3-CCHPh)(CO)5[P(OEt)3]L [L = CO; P(OEt)3] were determined by an X-ray diffraction study. The obtained compounds were studied by IR and 1H, 13C and 31P NMR spectroscopy. The spectroscopic study revealed that the clusters CpReFePt(μ3-CCHPh)(CO)5[P(OEt)3]L [L = CO; P(OEt)3] and CpReFePt(μ3-CCHPh)(CO)6[P(OPri)3] undergo isomerization upon dissolution, resulting in three isomers with different positions of the μ3-vinylidene ligand over the ReFePt core. The redox properties of the clusters were studied by electrochemical methods. The relatively stable cation-radicals obtained by chemical oxidation of CpReFePt(μ3-CCHPh)(CO)6[P(OPri)3] and CpReFePt(μ3-CCHPh)(CO)5[P(OEt)3]2 with ferrocenium tetrafluoroborate were characterized by EPR spectroscopy.

The New μ-Phenylvinylidene RePt Complexes Containing Platinum-Bound 1-(Isocyanomethylsulfonyl)- 4-Methylbenzene

The binuclear μ-vinylidene complexes containing an isocyanide ligand (1-(isocyanomethylsulfonyl)-4-methylbenzene) Cp(CO)2RePt(μ-C=CHPh)(TosMIC)(L) [L = PPh3 (1), P(OPri)3 (2)] were synthesized for the first time. The approach afforded 1 and 2 based on the substitution reactions of a platinum bound carbonyl group in Cp(CO)2RePt(μ-C=CHPh)(CO)(L) [L = PPh3 (1a), P(OPri)3 (2a)] upon addition of 1-(isocyanomethylsulfonyl)-4-methylbenzene. The complexes 1 and 2 were characterized by IR and NMR spectroscopy. Their redox properties were studied

Chemistry of vinylidene complexes. XXV. Synthesis and reactions of binuclear µ-vinylidene RePt complexes containing phosphite ligands. Spectroscopic, structural and electrochemical study

Reactions of Cp(CO)2ReCCHPh with Pt[P(OR)3]4 (R = Pri, Et, Ph) gave binuclear μ-vinylidene complexes Cp(CO)2RePt(μ-CCHPh)[P(OR)3]2. Treatment of the previously synthesized Cp(CO)2Re(μ-CCHPh)Pt(PPh3)2 with triisopropylphosphite or triethylphosphite resulted in a stepwise substitution of PPh3 ligands, leading to the disubstituted Cp(CO)2RePt(μ-CCHPh)[P(OR)3]2 and monosubstituted Cp(CO)2RePt(μ-CCHPh)[P(OR)3](PPh3) (R = Pri or Et) species, while no triphenylphosphine ligand substitution in the reaction with P(OPh)3 occurs at all. The monosubstituted Cp(CO)2RePt(μ-CCHPh)[P(OR)3](PPh3) (R = Pri, Et, Ph) species were also obtained by reacting Cp(CO)2ReCCHPh with mixed-ligand complexes Pt(PPh3)3L (L = P(OPri)3, P(OEt)3, P(OPh)3). Reactions of Cp(CO)2RePt(μ-CCHPh)LL′ (L = L′ = P(OPri)3, P(OEt)3, P(OPh)3; L = P(OPri)3, P(OEt)3, P(OPh)3, L′ = PPh3) with Co2(CO)9 yield tricarbonyl vinylidene species Cp(CO)2RePt(μ-CCHPh)[P(OR)3](CO) (R = Pri, Et, Ph). The obtained compounds were characterized by IR and 1H, 13C, 31P NMR spectroscopy. The molecular structures of Cp(CO)2RePt(μ-CCHPh)[P(OPri)3]2, Cp(CO)2RePt(μ-CCHPh)[P(OPri)3](PPh3) and Cp(CO)2RePt(μ-CCHPh)[P(OPri)3](CO) were determined by X-ray diffraction study. The redox properties of the new complexes and their reactions of chemical oxidation were studied.

Heterodinuclear Diphosphane-Bridged Iron–Platinum Diyne Complexes as Metalloligands for the Assembly of Polymetallic Systems (Fe, Pt, Co)

Treatment of [(OC)3Fe(μ-C=O)(µ-dppm)Pt(PPh3)] (1a) (dppm=Ph2PCH2PPh2) with 1,7-octadiyne affords the isomeric dimetallacyclopentenones [(OC)2Fe(µ-dppm)(µ-C(=O)C{(CH2)4C≡CH}=CH)Pt(PPh3)] (2a) and [(OC)2Fe(µ-dppm)(µ-C(=O)C(H)=C{(CH2)4C≡CH})Pt(PPh3)] (2a′). In a similar manner, the reaction with 1,3-diethynylbenzene and 1,4-diethynylbenzene yields [(OC)2Fe(μ-C(=O)C{C6H4–C≡CH}=CH)(μ-dppm)Pt(PPh3)] (2b,c); using [(OC)3Fe(μ-C=O)(µ-dppa)Pt(PPh3)] (1b) (dppa=Ph2PNHPPh2) as starting material provides [(OC)2Fe(μ-C(=O)C{p-C6H4–C≡CH}=CH)(μ-dppa)Pt(PPh3)] (2d). The isomeric μ-vinylidene complexes [(OC)3Fe(µ-dppm){(µ-C=CH(C6H4C≡CH)})Pt(PPh3)] (3b,c) result from treatment of [(OC)3Fe{Si(OMe)3}(μ-dppm)Pt(H)(PPh3)] with the two aromatic diynes. Reaction of 2a with a further equivalent of 1a yields the structurally characterized tetranuclear species [(OC)2Fe(µ-dppm)(µ-C(=O)C{(CH2)2}=CH)Pt(PPh3)]2 (4a). A dissymmetric heterotetranuclear dimetallacyclopentenone 4b is produced by reacting 2b with [(OC)3Fe(μ-C=O)(µ-dppa)Pt(PPh3)] (1b). An unusual heterotetranuclear dimetallacyclopentenone-μ-vinylidene compound 4c results from reaction of 3c with 1 equivalent of 1a. The dimetallacyclopentenone-dicobaltatetrahedrane cluster [(OC)2Fe(µ-dppm)(µ-C(=O)C{(CH2)4(η2-HC2Co2(CO)6}=CH)Pt(PPh3)] (5a) is formed by addition of [Co2(CO)8] to 2a. Likewise, [(OC)2Fe(µ-dppm)(µ-C(=O)C{C6H4(η2-HC2Co2(CO)4(µ-dppm)}=CH)Pt(PPh3)] (5b) is produced by mixing [Co2(CO)6(µ2-dppm)] with 2b. When attempting to prepare a heterotetranuclear complex by reacting 2a with [Co2(CO)6{P(OPh)3}2], the targeted compound was not formed. Instead, the substitution product [(OC)2Fe(µ-dppm)(µ-C(=O)C{(CH2)4C≡CH}=CH)Pt{P(OPh)3}] (6a) was isolated. 2b reacts in an analogous manner yielding [(OC)2Fe(μ-C(=O)C{C6H4–C≡CH}=CH)(μ-dppm)Pt{P(OPh)3}] (6b).

Chemistry of vinylidene complexes. XXIV. A new μ-vinylidene complex containing RePt core, and platinum-bound carbonyl ligand. Spectroscopic, structural and electrochemical study

The novel heterobinuclear μ-vinylidene complex [Cp(CO)2Re(μ-C=CHPh)Pt(PPh3)(CO)] (1) was isolated from the reaction mixture of [Cp(CO)2Re(μ-C=CHPh)Fe(CO)4] and Pt(PPh3)4 for the first time. Alternative high-yield synthetic approaches to 1 were developed including the reactions of [Cp(CO)2Re(μ-C=CHPh)Pt(PPh3)2] (2) with Co2(CO)8 and Rh(acac)(CO)2. The complex was characterized by IR and 1H, 13C and 31P NMR spectroscopy, a molecular structure of 1 was determined by X-ray diffraction analysis. The electrochemical behavior of the new complex was studied by cyclic voltammetry at platinum or glassed carbon electrodes and by dc polarography at a dropping mercury electrode.

Редокс-свойства биядерных рений-платиновых винилиденовых комплексов с фосфорсодержащими лигандами

The redox properties of new binuclear μ-vinylidene complexes Cp(CO)2RePt(μ-C = C2HPh)LL′ [L = СO, L′ = PPh3 (1); L = СO, L′ = P(OPr)3 (2); L = L′ = PPh3 (3); L = L′ = P(OPr)3 (4)] were studied by electrochemical methods at a platinum, a glassed carbon and a dropping mercury electrodes in acetonitrile solutions. It was established that one-electron oxidation of 3 and 4 results in a cleavage of the Re-Pt and Pt-C1 bonds affording vinylidene complex Cp(CO)2RePt = C = CHPh and [PtLL′] fragments. In contrast to complexes 3 and 4, one-electron oxidation of 1 and 2 is reversible, indicating the greater electrochemical stability of lasts relative to 3 and 4.

Chemistry of vinylidene complexes. XXII. Synthesis and physicochemical properties of the binuclear vinylidene complex [Cp(CO)2ReCu(μ-C[dbnd]CHPh)(μ-Cl)]2. Molecular structure of the new rheniumcopper complex

The interaction between Cp(CO)2ReCCHPh (1) and CuCl results in the new heterometallic μ-vinylidene complex [Cp(CO)2ReCu(μ2-CCHPh)(μ2-Cl)]2 (2) characterized earlier by IR and 1H, 13C NMR spectra. The molecular structure of compound 2 has been determined by X-ray diffraction analysis, revealing a dimer structure with two binuclear fragments linked to each other by asymmetric chloride bridges. The electrochemical behavior of 2 in acetonitrile was studied by cyclic voltammetry at a Pt-electrode.

Vinylidene carbonylation at a manganese–iron complex: A density functional study of mechanism

Treating the phenylvinyldene manganese complex Cp(CO) 2Mn C 1 C 2HPh, 1, with [Fe(CO) 4] yields the binuclear μ-vinylidene complex Cp(CO) 2MnFe(μ-C 1 C 2HPh)(CO) 4, 2, that further isomerizes to the carbonylated product η 4-[Cp(CO) 2MnC 1(CO)C 2HPh]Fe(CO) 3, 3. In a computational study of the mechanism using a hybrid density functional method, we considered two stereoisomers for species 2 and 3 where the phenyl group at center C 2 is oriented in cis ( E form) or trans ( Z form) fashion to the Cp(CO) 2Mn unit. Isomers 2E and 2Z were calculated to be degenerate whereas the experimentally detected species 3E is 8 kcal/mol more stable than its isomer 3Z. The two-step pathway 1 → 2Z → 3E was calculated to be the lowest-energy route with the highest activation barrier at 12 kcal/mol. The activation energy of the alternative single-step pathway 1 → 3E is 19 kcal/mol. We rationalized the stabilization of the ground state of 3E and the transition states leading to or starting from isomer 2Z as conjugation effect between the Mn–C C metallaallene fragment and the co-planar phenyl ring.

Preparation of Osmium η5-Phospholide Complexes and Their Reactions with Acyl Electrophiles: C═O Bond Cleavage and C−C Bond Formation within the Metal Coordination Sphere

Two diphosphaosmocene species have been pre pared in excellent yields by the reaction of a lithium 2,5-dialkylphospholide (alkyl = cyclohexyl, (−)-menthyl) and [(η6-cymene)OsCl2]2 in THF. These are the first examples of phosphametallocenes with an osmium core. For the success of the phosphaosmocene synthesis, the use of a sterically demanding phospholide is crucial. A treatment of the 2,2′,5,5′-Cy4-diphosphaosmocene with an AcCl/AlCl3 mixture in dichloromethane gives a novel (μ-vinylidene)osmium complex via activation of the acetyl C═O double bond. In the osmium complex, a μ-vinylidene moiety bridges between the osmium atom and a phosphorus of the η4-(P-oxophospholide). In the presence of excess acetyl electrophile, the μ-vinylidene complex is subjected to further acetylation at the CH2 terminus of the μ-vinylidene moiety to give a (μ-acetylvinylidene)osmium complex. A stepwise application of acetyl chloride and phenylacetyl chloride to this transformation enabled production of a [μ-(phenylacetyl)vinylide...

Unprecedented Formation of μ-Vinylidene Complexes from Phospharuthenocene and Acyl Chloride via Activation of the C═O Double Bond

A novel reaction mode of phosphametallocenes was discovered. The phospharuthenocenes with cyclohexyl substituents at the α-positions of the η5-phospholide(s) reacted with acyl electrophiles by an initial electrophilic attack to the ruthenium to produce the μ-alkenylidene species with activation of the acyl C═O double bond and elimination of an α-hydrogen.

Formation of (σ‐Alkenyl)‐ and (μ‐Vinylidene)palladium and ‐platinum Complexes by Oxidative Addition of 4,4‐Dichloro‐1,1‐diphenyl‐2‐azabuta‐1,3‐diene − The Molecular Structure of an Unusual Asymmetric (μ‐Vinylidene)Pd−Pd Complex

Abstract4,4‐Dichloro‐1,1‐diphenyl‐2‐azabuta‐1,3‐diene (1) oxidatively adds to [Pd(PPh3)4] and [Pt(C2H4)(PPh3)2] giving rise to the σ‐alkenyl complexes trans‐[MCl{[C(Cl)=C(H)−N=CPh2]}(PPh3)2] (2a: M = Pd; 2b: M = Pt). When 1 is treated with [Pd(PPh3)4] in a 1:2 ratio in refluxing toluene, the dimetallic μ‐vinylidene complex [(PPh3)ClPd{μ‐[C=C(H)−N=CPh2]}PdCl(PPh3)2] (3) is formed. In this fluxional compound, a PPh3 ligands migrates in a reversible manner between the two Pd centers. Substitution of the PPh3 ligands of 3 by 2 equiv. of Ph2PCH2PPh2 affords the A‐frame complex [ClPd(μ‐dppm)2{μ‐[C=C(H)−N=CPh2]}PdCl] (4). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

μ-Alkylidyne and μ-Alkylidene Complexes from a Bridging Side-on Vinylidene Sulfur-Rich Dimolybdenum Precursor

Reaction of the μ-vinylidene complexes [Mo2(η5-C5H5)2(μ-SMe)3(μ-η1:η2-CCHR)](BF4) (1; R = Tol (1a), n-Pr (1b)) with NaBH4 produced the μ-alkylidyne derivatives [Mo2(η5-C5H5)2(μ-SMe)3(μ-CCH2R)] (2; ...

Reactivity of Silyl-Substituted Heterobimetallic Iron–Platinum Hydride Complexes towards Unsaturated Molecules, I Alkyne Insertions into the Platinum-Hydride Bond, Phosphane-Induced σ-Alkenyl–μ-Vinylidene Rearrangements and Formation of μ-Isonitrile Complexes

The heterobimetallic hydride complexes [(OC)3Fe{Si(OMe)3}(μ-Ph2PXPPh2)Pt(H)(PR3)] (1a: X = CH2, PR3 = PPh3; 1b: X = NH, PR3 = PPh3; 1c: X = CH2, PR3 = PMePh2) have been prepared by the oxidative addition of [(OC)3Fe(H){Si(OMe)3}(η1-Ph2PXPPh2)] to [Pt(H2CCH2)(PPh3)2] or by reaction of K[(OC)3Fe{Si(OMe)3}(η1-dppm)] with trans-[Pt(Cl)(H)(PPh3)2]. The solid-state structure of compound 1b has been determined by single-crystal X-ray diffraction. 1-Alkynes such as methylpropiolate or phenylacetylene insert in a regiospecific manner into the Pt–H bond of 1 to yield the σ-alkenyl complexes [(OC)3Fe{μ-Si(OMe)2(OMe)}(μ-Ph2PXPPh2)Pt{C(R)=CH2}] (2a: X = CH2, R = CO2Me; 2b: X = NH, R = CO2Me; 3a: X = CH2, R = Ph). Addition of the Pt–H bond of 3a across the triple bond of [D1]phenylacetylene affords [(OC)3Fe{μ-Si(OMe)2(OMe)}(μ-dppm)Pt{C(Ph)=C(D)H}] (3a*) having the deuteron trans to platinum (cis addition). This insertion reaction is accompanied by dissociation of the platinum-bonded PR3 ligand and saturation of the vacant coordination site by a dative μ-η2-Si–OPt interaction. When 3 is treated with PR3 again, a subsequent phosphane-induced rearrangement leading to vinylidene-bridged complexes [(OC)3Fe{μ-CC(H)R′}(μ-Ph2PXPPh2)Pt(PR3)] (4a: X = CH2, R′ = Ph, PR3 = PPh3; 4b: X = NH, R′ = Ph, PR3 = PPh3; 4c: X = CH2, R′ = Ph, PR3 = PMePh2; 4d: X = CH2, R′ = p-tolyl, PR3 = PPh3) occurs. Upon purging a solution of 3a with carbon monoxide, the labile CO adduct [(OC)3Fe{Si(OMe)3}(μ-dppm)-Pt(CO){C(Ph)=CH2}] 5a is formed, addition of 2,6-xylyl isocyanide to 2a and 3a affords the isonitrile adducts [(OC)3Fe{Si(OMe)3}(μ-dppm)Pt(CNxylyl){C(R)=CH2}] (5b: R = CO2Me; 5c: R = Ph), respectively. When hydride complex 1a is allowed to react with stoichiometric amounts of aromatic isonitriles, formal elimination of HSi(OMe)3 occurs, yielding the heterodinuclear isonitrile-bridged complexes [(OC)3Fe(μ-C=N-R)(μ-dppm)Pt(PPh3)] (6a: R = 2,6-xylyl; 6b: R = o-anisyl; 6c: R = p-anisyl; 6d: R = p-C6H4NH2) and the bis(isonitrile) complexes [(OC)2(RN≡C)Fe(μ-C=N–R)(μ-dppm)Pt(PPh3)] (7a: R = 2,6-xylyl; 7b: R = p-anisyl). Single-crystal X-ray diffraction studies perfomed on 6a and 6b reveal that the molecular structures of these μ-isonitrile complexes closely resemble the μ-vinylidene complexes 4. The two metal centers are bridged in a symmetric manner by strongly bent CNR ligands, the aromatic groups R being oriented towards the Fe(CO)3 moiety. Electrophilic addition of HBF4 to the basic nitrogen atom of the μ-CNR ligand transforms 6 to the cationic μ-aminocarbyne complexes [(OC)3Fe{μ-CN(H)R}(μ-dppm)Pt(PPh3)][BF4] (8a: R = 2,6-xylyl; 8b: R = p-anisyl; 8c: R = p-C6H4NH2).

Infrared study of transformation of a terminal carbonyl ligand into a bridging one in the MnPt and MnPd μ-vinylidene complexes

The IR study of a series of heterometallic vinylidene-bridged complexes CP(CO) 2MnM( μ-C = CHPh)LL′, where M = Pt or Pd, L and L′ = CO, tert-phosphites, PPh 3, Ph 2P(CH 2) nPPh 2, n = 1–3, demonstrated the existence of a gradual transformation of one of the terminal CO groups at the Mn atom into bridging one spanning the Mn-M bond, which goes through the intermediate semi-bridging form and is induced by the electron-donating capacities of ligands L and L′ at the M atom.

Reactivity of Silylated Dinuclear Iron−Platinum Acyl Complexes: Formation of μ-Vinylidene Complexes and Crystal Structures of the Acyl Complex [(OC)3{(MeO)3Si}Fe(μ-dppm)Pt{C(O)Me}(t-BuNC)] and the μ-Vinylidene Complex [(OC)3Fe{μ-CC(H)Ph}(μ-dppm)Pt(PPh3)

Addition of RNC to the heterobimetallic acyl complex [(OC)3Fe{μ-Si(OMe)2(OMe)}(μ-dppm)Pt{C(O)Me}] (1a), which displays a μ−η2-Si−O bridge, afforded the isonitrile adducts [(OC)3{(MeO)3Si}Fe(μ-dppm)Pt{C(O)Me}(C⋮NR)] (3a R = t-Bu, 3b R = 2,6-xylyl). Upon treatment of a CH2Cl2 solution of 1a with MeO2CC⋮CCO2Me (DMAD), alkyne insertion into the Pt−C bond gave the alkenyl complex [(OC)3Fe{μ-Si(OMe)2(OMe)}(μ-dppm)Pt{(MeO2C)CC(CO2Me)C(O)Me}] 4. The isonitrile adducts [(OC)3{(MeO)3Si}Fe(μ-dppm)Pt{(MeO2C)CC(O2Me)C(O)Me}(C⋮NR)] (5a R = t-Bu, 5b R = 2,6-xylyl)] were isolated after addition of RNC. A more complex reaction occurred when phenylacetylene or tert-butylacetylene were reacted with 1a. The iron-bound Si(OMe)3 group and the organic ligand coordinated on platinum were eliminated, and the vinylidene-bridged complexes [(OC)3Fe{μ-CC(H)R}(μ-dppm)Pt(CO)] (6a R = Ph, 6b R = t-Bu, 6c R = n-Bu) were obtained. The loosely Pt-bound CO ligand of 6a−c was readily displaced by PPh3, P(OMe)3, or 2,6-xylyl isonitrile yielding the substitution products [(OC)3Fe{μ-CC(H)R}(μ-dppm)Pt(L)] (7a R = Ph, L = PPh3; 7b R = t-Bu, L = PPh3; 7c R = t-Bu, L = P(OMe)3; 7d R = t-Bu, L = 2,6-xylylNC). The heterobimetallic phenyl complex [(OC)3Fe{μ-Si(OMe)2(OMe)}(μ-dppm)Pt(Ph)] (8) was obtained by reaction of K[Fe{Si(OMe)3}(CO)3(η1-dppm)] with a cold THF solution of [PtCl(Ph)(1,5-COD)]. The μ−η2-Si−O bridge is readily opened under a CO atmosphere to give the CO adduct [(OC)3Fe{Si(OMe)3}(μ-dppm)Pt(CO)(Ph)] (9), which unexpectedly does not insert CO into the Pt−phenyl bond. This complex reversibly loses the CO ligand under reduced pressure to regenerate 8. All complexes have been studied by multinuclear NMR spectroscopy. The solid state structures of complexes 3a and 7a have been determined by single-crystal X-ray diffraction.

Synthesis and Structures of the μ-Vinylidene Binuclear Nickel Complexes [Ni2(μ-CCH2)(dmpm)2Cl2] and [Ni2(μ-CCH2)(dppm)2Br2]: Comparison of the Electronic Structures of Nickel A-Frames

The reaction of bis(cyclooctadiene)nickel(0) with bis(dimethylphosphino)methane (dmpm) and 1,1-dichlorovinylidene in THF yields the vinylidene-bridged binuclear nickel A-frame complex [Ni2(μ-CCH2)(dmpm)2Cl2] (1a). The structure of 1a was determined by X-ray crystallography. The Ni−Ni separation is 2.898(2) A, and the vinylidene carbon−carbon bond distance is 1.35(2) A. The structure of the bis(diphenylphosphino)methane (dppm) bridged μ-vinylidene complex [Ni2(μ-CCH2)(dppm)2Br2] (2b) was also determined by X-ray crystallography. The Ni−Ni separation of 2.874(2) A for 2b is comparable to that of 1a. The series of μ-vinylidene nickel A-frames with substituted terminal ligands [Ni2(μ-CCH2)(PR2CH2PR2)2X2] (X = Cl, Br, I, R = Me; X = Cl, Br, I, NCS, OCN; R = Ph) were prepared and characterized. The nickel A-frames with different bridging ligands [Ni2(μ-CE)(dppm)2Cl2] (E = O, NPh) were also examined. Extended Huckel molecular orbital (EHMO) calculations indicate that the HOMO in these nickel A-frame complexes is...

Chemistry of vinylidene complexes XI. Synthesis of trinuclear MnFePt complexes by means of consecutive assembling out of mono- and dimetal vinylidene precursors

The dimetal μ-vinylidene complexes Cp(CO) 2MnPt( μ-C = CHPh)L 2 (L = tert.-phosphine or -phosphite), which have been obtained by coupling of the mononuclear complex Cp(CO) 2Mn=C=CHPh and unsaturated PtL 2 unit, add smoothly the Fe(CO) 4 moiety to produce trimetal MnFePt compounds. The μ 3-vinylidene cluster CpMnFePt( μ 3-C=CHPh)(CO) 6(PPh 3) was prepared in quantitative yields from the reactions of Cp(CO) 2MnPt( μ-C=CHPh)(PPh 3)L (L = PPh 3 or CO) with Fe 2(CO) 9 in benzene at 20 °C. The phosphite-substituted complexes Cp(CO) 2Mnpt( μ-C=CHPh)L 2 (L = P(OEt) 3 or P(OPr i) 3) react under analogous conditions with Fe 2(CO) 9 to give mixtures (2:3) of the penta- and hexacarbonyl clusters, CpMnFePt( μ 3-C = CHPh)(CO) 5L 2 and CpMnFePt( μ 3-C = CHPh)(CO) 6L, respectively. The similar reaction of the dimetal complex Cp(CO) 2MnPt( μ-C = CHPh)(dppm), in which the Pt atom is chelated by dppm = Ph 2PCH 2PPhPin2 ligand, gives only a 15% yield of the analogous trimetal μ 3-vinylidene hexacarbonyl product CpMnFePt( μ 3-C = CHPh)(CO)(dppm), but the major product (40%) is the tetranuclear μ 4-vinylidene cluster (dppm)PtFe 3( μ 4-C = CHPh)(CO) 9. The IR and 1H, 13C and 31P NMR data for the new complexes are reported and discussed.

IR study of molecular structure and conformation of μ-vinylidene Mn-Pt complexes

Based on the experimental data for Mn and Pt μ-vinylidene complexes existence of spatial isomers has been shown. Mechanism of their formation and influence of Pt atom ligand surroundings on the given process are discussed.

Photochemical head-to-head (R  H) vs. head-to-tail dimerization (R  Ph) of iron acetylide complexes (η 5-C 5Me 5)Fe(CO) 2CCR leading to a dimetallacyclopentenone and a μ-vinylidene complex

Irradiation of a benzene solution of iron acetylides Fp★CCR (R  H, Ph) results in dimerization of the RCC ligand to give dinuclear complexes with completely different structures, i.e. a dimetallacyclopentenone Cp 2 ★Fe 2(CO)(μ-CO)[μ-η 1 : η 3 C(CCH)CHC(O)] (R  H) and a μ-vinylidene complex Cp 2 ★Fe 2(CO) 2(μ-CC(Ph)CCPh)] (R  Ph), depending on the substituent (R). The formation of the products has been interpreted in terms of head-to-head (R  H) and head-to-tail coupling (R  Ph) of the alkynyl ligands within the coordination sphere of the Cp★Fe(CO) fragment.

Reaction of the cationic diiron .mu.-(.eta.1:.eta.2)acetylide complexes [(FP)2(C.tplbond.CR)]BF4 (R = H, Ph) with NaOMe

The reaction of [(Fp*) 2 (C≡CH)]BF 4 (1a; Fp*=(η 5 -C 5 Me 5 )Fe(CO) 2 ) with NaOMe in THF results in deprotonation to afford Fp*C≡CFp*. On the other hand, the reaction of [(Fp) 2 (C≡CPh)]BF 4 (Fp=(η 5 -C 5 H 5 )Fe(CO) 2 ) with NaOMe produces the metallacyclic adduct Cp(OC)Fe[C-(Ph)=C(Fp)C(=O)OMe], whose structure has been confirmed by derivatization to (Z)-3-Fp(Ph)=C-(H)COOMe by acid hydrolysis. The reaction of [(Fp*) 2 (C≡CPh)]BF 4 witrh NaOMe gives a complicated mixture containing the mononuclear metallacyclic complex Cp*(OC)Fe[C(Ph)=C(H)C(=O)OMe] and the dinuclear μ-vinylidene complex (Cp*) 2 Fe 2 (CO) 2 (μ-CO)[μ-C=C(Ph)COOMe]