Synthesis of a linear-type pentanuclear (RhIII-WVI-CuI-WVI-RhIII) sulfide cluster predicted by fast atom bombardment mass spectrometry

The positive ion FAB mass spectrum of a linear trinuclear sulfide cluster, [Cp^*RhP(OEt)₃(-WS₄CuCl] (1; Cp^* = ⁵-C₅Me₅), shows many ions heavier than the molecular ion. One of the envelopes corresponds to a pentanuclear cationic cluster of [{Cp^*RhP(OEt)₃(WS₄)}₂Cu]⁺. It has been synthesized by a reaction between [Cp^*RhP(OEt)₃WS₄] and Cu⁺ in a 2:1 molar ratio as the PF₆ salt [{Cp^*RhP(OEt)₃(-WS₄)}₂Cu][PF₆] (2 · PF₆), which is characterized by a single-crystal X-ray diffraction, EXAFS, and IR measurements.This paper is dedicated to Professor Jiaxi Lu on the occassion of this 80th birthday and in recognition of his pioneering contribution to this field.     

Activation of biscyclopentadienyl hydride complexes of titanium and aluminum by NH- and OH-acids in the reactions of hydrogenation of olefins. Crystal and molecular structures of {(η5−Cp)2Ti(μ−H)2AlH]μ−N(C2H4)4O]}2 and [(η5−Cp)2Ti(μ−H(2AlH]2(μ−OC2H4OMe)[(μ1:μ5−C5H4)Ti(μ5−Cp)(μ−H)]2*

The reactions of Cp₂TiH₂AlH₂·Et₂O (1) with HN(C₂H₄)₂O, HOC₂H₄OMe, and water afforded the complexes {Cp₂TiH₂AlH[μ-N(C₂H₄)₂O]}₂ (5), [Cp₂TiH₂AlH(μ-OC₂H₄OMe)]₂ (6) and (Cp₂TiH₂AlH)₂O (4), respectively. Compounds 5 and 6 are dimers containing bridging Al?E₂?Al fragments (E=N or O). Complex 6 in solution converted to the hexanuclear compound [(η⁵?Cp)₂Ti(μ?H(₂AlH]₂(μ?OC₂H₄OMe)[(μ¹:μ⁵?C₅H₄)Ti(μ⁵?Cp)(μ?H)]₂ (8). The structures of complexes 5 and 8 were established by X-ray diffraction analysis. The rates of hydrogenation of hex-1-ene were determined using compounds 4–6 and the complexes [Cp₂TiH₂AlH(NEt₂)]₂ and [Cp₂TiH₂AlH(OEt)]₂ as catalysts. The probable mechanism of hydrogenation with the participation of bimetallic hydride complexes of aluminum and titanocene is discussed.     

Stereoselective formation of phenylthio groups substituted 1-metalla-3-titanacyclobutanes

Desulfurizative titanation of group 14 metal compounds bearing two or four bis(phenylthio)methyl groups with the low-valent titanium reagent Cp₂Ti[P(OEt)₃]₂ produced phenylthio groups substituted 1-metalla-3-titanacyclobutanes stereoselectively. The molecular structures of the titanacycles were unambiguously confirmed by X-ray diffraction analysis.     

Formation of conjugated dienes by the reaction of titanocene alkenylidene complexes with alkynes

Titanocene alkenylidene complexes, generated by the reductive metallation of 1,1-dichloro-1-alkenes with the titanocene(II) species Cp₂Ti[P(OEt)₃]₂, reacted with alkynes to produce conjugated dienes.     

A new route to alkenylcyclobutenes

Reaction of titanium cyclobutylidene complexes, prepared by the desulfurizative titanation of 1,1-bis(phenylthio)cyclobutanes with Cp₂Ti[P(OEt)₃]₂, with alkynes gave 1-(alk-1-enyl)cyclobutenes.     

The first evidence for a stereostable centrometalled chirality in a dicyclopentadienyltantalum complex

Reaction of dichlorophenylphosphine with monohydrides Cp₂M(CO)H (M = Nb or Ta) gives the salts [Cp₂M(CO)(PPhClH(]⁺ Cl⁻ in good yields. In a basic medium these salts give the neutral complexes Cp₂M(CO) [P(O)(H)Ph]. In a reaction starting from the chiral hydride Cp^* CpTa(CO)H, (Cp^* = C₅Me₅), two diastereoisomers are obtained, and can be isolated as stereostable structures.     

Ligand exchange reactions of the alkyluranium(III) complexes (η5-C5H5)3URLi

The Cp₃URLi compounds (Cp = η⁵-C₅H₅; R = Me, n-Bu, n-Pent) have been synthesized by reaction of CP₃U(THF) with 1 equivalent of RLi. Exchange of the R alkyl occurs on treatment with alkyllithium reagents or in hydrogenolysis in the presence of a terminal olefin. These reactions presumably involve the Cp₃U and Cp₂UR species which are in equilibrium with the Cp₃URLi complexes.     

Synthesis,structure and thermal rearrangement of tetramethyldisilane-bridged bis(cyclopentadienyl) diiron complexes with a phosphite or phosphine ligand substitution

Photolysis of tetramethyldisilane-bridged bis(cyclopentadienyl) tetracarbonyl di-iron in the presence of phosphite or phosphine ligand afforded the corresponding Fe–Fe bond complexes with one carbonyl replaced by a phosphite or phosphine ligand: [(Me₂SiSiMe₂)Cp₂Fe₂(CO)(PR₃)(μ-CO)₂] (R=OPh, 1; OEt, 2; Ph, 3). When these complexes were heated in refluxing xylene, they become rearranged to the corresponding products [(Me₂SiCpFe)₂(CO)₃(PR₃)] (R=OPh, 4; OEt, 5; Ph, 6). It was found that, after phosphite or phosphine ligand substitution, the rearrangement became facile. The molecular structures of 1–6 were characterized by IR, ¹H NMR spectra and elemental analyses. The crystal structures of 1 and 4 were determined by X-ray diffraction analysis.     

Reaktionen von Cyclostibanen (RSb)n [R = (Me3Si)2CH,n = 3; Me3CCH2, n = 4, 5] mit den Übergangsmetallcarbonyl‐Komplexen [W(CO)5(thf)], [CpxMn(CO)2(thf)], [CpxCr(CO)3]2 und [Co2(CO)8]; Cpx = MeC5H4

Reactions of Cyclostibanes, (RSb)_n [R = (Me₃Si)₂CH, n = 3; Me₃CCH₂, n = 4, 5] with the Transition Metal Carbonyl Complexes [W(CO)₅(thf)], [Cp^xMn(CO)₂(thf)], [Cp^xCr(CO)₃]₂, and [Co₂(CO)₈]; Cp^x = MeC₅H₄ (RSb)₃ [R = (Me₃Si)₂CH] reacts with [W(CO)₅(thf)], [Cp^xMn(CO)₂(thf)], or [Co₂(CO)₈] to give [(RSb)₃W(CO)₅] ( 1 ), [RSb{Mn(CO)₂Cp^x}₂] ( 2 ) or [RSbCo(CO)₃]₂ ( 3 ). The reaction of (R′Sb)_n (n = 4, 5; R′ = Me₃CCH₂) with [Cp^xCr(CO)₃]₂ leads to [(R′Sb)₄{Cr(CO)₂Cp^x}₂] ( 4 ); Cp^x = MeC₅H₄, thf = Tetrahydrofuran.     

Synthesis and properties of dicyclopentadienyltantalum(III) carbonyl compounds

Reaction of Cp₂Ta(H)L (L = C₃H₆, C₄H₈, C₅H₁₀ and C₅H₈) with CO under mild conditions gives alkyltantalum carbonyl complexes Cp₂Ta(CO)R (R = C₃H₇, C₄H₉, C₅H₁₁ and C₅H₉, respectively). Depending upon the position of the olefin relative to the hydride ligand in the hydride-olefin complex, Cp₂Ta(CO)H is also formed during the carbonylation reaction. Reduction of Cp₂TaCl₂ by potassium or t-BuMgCl under one atmosphere of CO affords the very stable compound Cp₂Ta(CO)Cl in moderate yields. Reaction of Cp₂Ta(CO)Cl with RLi or RMgX does not give the Cp₂Ta(CO)R complex.     

Bi- and triheteronuclear complexes of uranium and group VI transition metals

The new heterobimetallic compounds Cp₃U[OCM(CO)₂Cp′] containing uranium and group VI transition metals are synthesized from Cp₃UCl and Na[M(CO)₃Cp′] or from Cp₃UCH₃ and H[M(CO)₃Cp′] (M = Mo, W; Cp = C₅H₅; Cp′ = C₅H₅ or C₅Me₅). In a same manner, the trimetallic Cp₂U[OCMo(CO) ₂Cp]₂ is obtained starting from Cp₂U(NEt₂)₂ and H[Mo(CO)₃Cp]. All these complexes exhibit low CO stretching frequencies characteristic of isocarbonyl linkages between uranium and Mo or W atoms.     

Employing (half-)titanocene complexes as initiators for the synthesis of end-functionalized polylactides by coordination polymerization

Seven (half-)titanocene alkoxide complexes, [Cp₂TiCl(OEt)], [Cp₂TiCl(O-2-Bu)], [Cp₂TiCl(OCH₂CF₂CF₂H)], [CpTiCl₂(OEt)], [CpTiCl₂(O-(S)-2-Bu)], [CpTiCl₂(OCH₂CF₃)], and [Cp₂TiCl(OCH₂CF₃)], were synthesized and employed in lactide coordination polymerization. These organotitanium (IV) compounds proved to be very efficient initiators for the ring-opening polymerization of enantiomeric l -lactide and racemic mixture of rac-lactide, leading to end-functionalized polymers. Kinetic studies illustrated that these compounds produce well-defined polymers in a controlled manner. This was further demonstrated by synthesizing poly(l -lactide-b-hexyl isocyanate) diblock copolymer. The effect of the alkoxy end groups on the thermal behavior of the polymers was also studied by thermogravimetric analysis and differential scanning calorimetry. The polymers were characterized using size exclusion chromatography and proton nuclear magnetic resonance spectroscopy. The optical properties of the diblock copolymer were also investigated. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2192–2202     

Isolierung und struktur eines Cp2TiIV-komplexes mit dem dianion des bis(ethoxythiophosphorsäure)disulfids als chelatligand: Cp2Ti(P2S4O2(OEt)2)

Ethanolysis of P₄S₁₀ in the presence of Cp₂TiCl₂ and some H₂O produces the red air-stable complex Cp₂Ti(P₂S₄O₂(OEt)₂) (A) in which the dianion of bis(ethoxythiophosphoric acid)-disulfide acts as chelating ligand, bonded via two oxygen atoms to Ti. The molecular structure of A has been determined by X-ray diffraction. A crystallizes in the orthorhombic space group Pca2₁ with a 15.559(4), b 9.622(3), c 14.326(4) Å and Z = 4.     

Formation of pyrrolidines by the titanocene(II)-promoted intramolecular reaction of N-[3,3-bis(phenylthio)propyl]anilides

The reaction of anilides with the titanium carbene complexes generated by the desulfurization of thioacetals with the titanocene(II) species Cp₂Ti[P(OEt)₃]₂ produced the corresponding enamines. Unusual formation of pyrrolidines was observed when N-[3,3-bis(phenylthio)propyl]anilides were treated with the titanocene(II) reagent.     

The structure and formation of niobocene carbonyl heteronuclear derivatives. The molecular structures of Cp2Nb(CO)(μ-CO)Mn(CO)4, Cp2Nb(CO)(μ-H)Ni(CO)3 and [Cp2Nb(CO)(μ-H)]2Mo(CO)4

The heteronuclear Cp₂Nb(CO)(μ-CO)Mn(CO)₄ (I), Cp₂Nb(CO)(μ-H)Ni(CO)₃ (II) and [Cp₂Nb(CO)(μ-H)]₂M(CO)₄ (III, M = Mo;IV, M = W) complexes were prepared by reaction of Cp₂NbBH₄/Et₃N with Mn₂(CO)₁₀ in refluxing toluene, direct reaction of Cp₂NbBH₄ with Ni(CO)₄ in ether, and reaction of Cp₂NbBH₄/Et₃N with M(CO)₅. THF complexes (M = Mo or W) in THF/benzene mixture. An X-ray investigation of compounds I–III was performed. It is established that in I the bonding between Mn(CO)₅ and Cp₂Nb(CO) (with the angle (α) between the ring planes being 44.2(5)°) fragments takes place via a direct NbMn bond (3.176(1) Å) and a highly asymmetric carbonyl bridge (MnC_co 1.837(5) Å, NbC_co 2.781(5) Å). On the other hand, in complex II the sandwich Cp₂Nb(CO)H molecule (angle α = 37.8°) is combined with the Ni(CO)₃ group generally via a hydride bridge (NbH 1.83 Å, NiH 1.68 Å, NbHNi angle 132.7°) whereas the large Nb?Ni distance, 3.218(1) Å, shows the weakening or even absence of the direct NbNi bond. Similarly, in complex III two Cp₂Nb(CO)H molecules (with α angles equal to 41.4 and 43.0°, respectively) are joined to the Mo(CO)₄ group via the hydride bridges (NbH 1.83 and 1.75 Å and MoH 2.04 and 2.06 Å) producing a cis-form. The direct NbMo bonds are probably absent, since the Nb?Mo distances are rather long (3.579 and 3.565 Å). The effect of electronic and steric factors on the structure of heteronuclear niobocene carbonyl derivatives is discussed.     

Reactions of alkaline earth metal or al slurries with bis-cyclopentadienyl complexes of some early transition metals

Slurries of Mg, Ca, Ba and Al, prepared by cocondensation of metal vapour with volatile organic solvents, especially toluene, at –196°C, reacted at ambient temperature with some bis-cyclopentadienyl complexes of Ti, Zr, Hf, V and Cr. [TiCl₂Cp₂] (Cp = η⁵-C₅H₅) with slurries Al in hexane or toluene, or Mg or Ba, in toluene, formed [TiClCp₂]₂ accompanied by side-products. From related reactions with slurries of Mg in tetrahydrofuran (THF), [TiCl₂Cp(THF)] was obtained and with Ca-toluene slurries an unstable paramagnetic dihydrido complex of Ti(III) was observed by using ESR spectroscopy. Reactions of [TiPh₂Cp₂ with slurries of Al or Ba in toluene yielded a form of “titanocene” (TiC₁₀H₁₀) and ESR studies of these reactions revealed related paramagnetic species in solution. Reaction of slurries of Al, Mg or Ba with [TiMe₂Cp₂] produced several different paramagnetic products which were studied by ESR spectroscopy, and the reaction of metal slurries with the complexes [MR₂Cp₂] (M = Ti, R = OPh; M = Zr or Hf, R = Cl or Me), [VRCp₂] (R = Cl or Me), and [CrCp₂] are also reported.     

Catenated polysulfur ligands: the pentasulfides of di-η5-cyclopentadienyl-zirconium(IV) and -hafnium(IV)

The thiols Cp₂M(SH)₂, where M = Ti and Zr, react to form the complexes Cp₂MS₅ when treated with mono- and di-sulfur transfer reagents. Treatment of Cp₂MCl₂ with Li₂S₂ and sulfur gave Cp₂MS₅, M = Ti, Zr and Hf, in better yield. The new Zr and Hf complexes have a six-membered MS₅ ring in a chair conformation similar to the previously observed for M = Ti. Variable temperature NMR studies show that the barriers to MS₅ ring inversion decrease in the order Ti > Hf > Zr.     

Synthese und Charakterisierung von Metallocen-Chelaten heterocyclischer 1,2-Diselenolate

Synthesis and Characterization of Metallocene Chelates of Heterocyclic 1,2-Diselenolates Synthesis and properties of metallocen diselenolates Cp₂^RML (Cp^R = η⁵-C₅H₄CH₃ (Cp′); η⁵-C₅(CH₃)₄ C₂H₅ (Cp^o)) of titanium(IV) and vanadium(IV) with L = dsit (1,3-dithiole-2-thione-4,5-diselenolate), dsise (1,3-dithiole-2-selone-4,5-diselenolate) dsitse (1,3-thiaselenole-2-selone-4,5-diselenolate) and dsis (1,3-diselenole-2-selone-4,5-diselenolate) are described. The structures of these compounds in solution are discussed using ¹H, ¹³C, ⁷⁷Se NMR and EPR data. Their voltammetric behaviour is investigated in dichloromethane. The activation parameters of the chelate ring inversion of the titanocene diselenolates (Cp₂^RTiL) and the x-ray structures of Cp₂′Ti(dsit), Cp₂^oTi(dsit); Cp₂^oTi(dsise) (2 modifications) and Cp₂^oTi(dsis) are reported.     

Synthesis and Characterization of Multiferrocenyl‐Substituted Group 4 Metallocene Complexes

The reaction of different metallocene fragments [Cp₂M] (Cp=η⁵‐cyclopentadienyl, M=Ti, Zr) with diferrocenylacetylene and 1,4‐diferrocenylbuta‐1,3‐diyne is described. The titanocene complexes form the highly strained three‐ and five‐membered ring systems [Cp₂Ti(η²‐FcC₂Fc)] ( 1 ) and [Cp₂Ti(η⁴‐FcC₄Fc)] ( 2 ) (Fc=[Fe(η⁵‐C₅H₄)(η⁵‐C₅H₅)]) by addition of the appropriate alkyne or diyne to Cp₂Ti. Zirconocene precursors react with diferrocenyl‐ and ferrocenylphenylacetylene under C? C bond coupling to yield the metallacyclopentadienes [Cp₂Zr(C₄Fc₄)] ( 3 ) and [Cp₂Zr(C₄Fc₂Ph₂)] ( 5 ), respectively. The exchange of the zirconocene unit in 3 by hydrogen atoms opens the route to the super‐crowded ferrocenyl‐substituted compound tetraferrocenylbutadiene ( 4 ). On the other hand, the reaction of 1,4‐diferrocenylbuta‐1,3‐diyne with zirconocene complexes afforded a cleavage of the central C? C bond, and thus, dinuclear [{Cp₂Zr(μ‐η¹:η²‐C?CFc)}₂] ( 6 ) that consists of two zirconocene acetylide groups was formed. Most of the complexes were characterized by single‐crystal X‐ray crystallography, showing attractive multinuclear molecules. The redox properties of 3 , 5 , and 6 were studied by cyclic voltammetry. Upon oxidation to 3 ⁿ⁺, 5 ⁿ⁺, and 6 ⁿ⁺ (n=1–3), decomposition occured with in situ formation of new species. The follow‐up products from 3 and 5 possess two or four reversible redox events pointing to butadiene‐based molecules. However, the dinuclear complex 6 afforded ethynylferrocene under the measurement conditions.     

Trinuclear Phosphaferroles from Alkylidyne‐Phosphaalkyne Coupling Reactions

Reaction of bisalkylidyne cluster compounds [Fe₃(CO)₉(μ₃‐CR)₂] ( 1a—d ) ( a , R = H; b , R = F; c , R = Cl; d , R = Br) with the phosphaalkyne t‐C₄H₉‐C≡P ( 2 ) yield a single isomer of the phosphaferrole cluster [Fe₃(CO)₈][CR‐C(t‐Bu)‐P‐CR] ( 3a—d ). However, the three isomeric compounds [Fe₃(CO)₈][C(OEt)‐C(t‐Bu)‐P‐C(Me)] ( 5a ), [Fe₃(CO)₈][C(Me)‐C(t‐Bu)‐P‐C(OEt)] ( 5b ), and [Fe₃(CO)₈][C(OEt)‐C(Me)‐C(t‐Bu)‐P] ( 5c ) are obtained in the reaction of [Fe₃(CO)₉(μ₃‐CMe)(μ₃‐C‐OEt)] ( 4 ) with 2 . As the phosphaferroles 3 possess a lone pair of electrons at the phosphorus atom they can act as ligands. [Fe₃(CO)₈][CF‐C(t‐Bu)‐P‐CF]ML_n ( 7a—c ) ( a , ML_n = Cr(CO)₅; b , ML_n = CpMn(CO)₂; c , ML_n = Cp^*Mn(CO)₂) were formed from 3b and L_nM(η²‐C₈H₁₄) ( 6a—c ). The dinuclear cluster [Fe₂(CO)₆][CF‐CF‐C(t‐Bu)‐PH(OMe)] ( 8 ) was obtained from 3b and NiCl₂·6H₂O in methanol. The structures of 3a—d , 5a—c , 7b , and 8 have been elucidated by X‐ray crystal structure determinations.