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1.
Four‐Membered Heterometallacyclic d0 and d1 Complexes of Group 4 Metallocenes with Amidato Ligands
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Dr. Martin Haehnel Jacqueline B. Priebe Jacky C.‐H. Yim Dr. Anke Spannenberg Prof. Dr. Angelika Brückner Prof. Dr. Laurel L. Schafer Prof. Dr. Uwe Rosenthal 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(25):7752-7758
A study of the coordination chemistry of different amidato ligands [(R)N?C(Ph)O] (R=Ph, 2,6‐diisopropylphenyl (Dipp)) at Group 4 metallocenes is presented. The heterometallacyclic complexes [Cp2M(Cl){κ2‐N,O‐(R)N?C(Ph)O}] M=Zr, R=Dipp ( 1 a ), Ph ( 1 b ); M=Hf, R=Ph ( 2 )) were synthesized by reaction of [Cp2MCl2] with the corresponding deprotonated amides. Complex 1 a was also prepared by direct deprotonation of the amide with Schwartz reagent [Cp2Zr(H)Cl]. Salt metathesis reaction of [Cp2Zr(H)Cl] with deprotonated amide [(Dipp)N?C(Ph)O] gave the zirconocene hydrido complex [Cp2M(H){κ2‐N,O‐(Dipp)N?C(Ph)O}] ( 3 ). Reaction of 1 a with Mg did not result in the desired Zr(III) complex but in formation of Mg complex [(py)3Mg(Cl) {κ2‐N,O‐(Dipp)N?C(Ph)O}] ( 4 ; py=pyridine). The paramagnetic complexes [Cp′2Ti{κ2‐N,O‐(R)N?C(Ph)O}] (Cp′=Cp, R=Ph ( 7 a ); Cp′=Cp, R=Dipp ( 7 b ); Cp′=Cp*, R=Ph ( 8 )) were prepared by the reaction of the known titanocene alkyne complexes [Cp2′Ti(η2‐Me3SiC2SiMe3)] (Cp′=Cp ( 5 ), Cp′=Cp* ( 6 )) with the corresponding amides. Complexes 1 a , 2 , 3 , 4 , 7 a , 7 b , and 8 were characterized by X‐ray crystallography. The structure and bonding of complexes 7 a and 8 were also characterized by EPR spectroscopy. 相似文献
2.
A process of ion‐pair formation in the system Cp2ZrMe2/methylaluminoxane (MAO) has been studied by means of density functional theory quantum‐chemical calculations for MAOs with different structures and reactive sites. An interaction of Cp2ZrMe2 with a MAO of the composition (AlMeO)6 results in the formation of a stable molecular complex of the type Al5Me6O5Al(Me)O–Zr(Me)Cp2 with an equilibrium distance r(Zr–O) of 2.15 Å. The interaction of Cp2ZrMe2 with “true” MAO of the composition (Al8Me12O6) proceeds with a tri‐coordinated aluminum atom in the active site (OAlMe2) and yields the strongly polarized molecular complex or the μ‐Me‐bridged contact ion pair ( d ) [Cp2(Me)Zr(μMe)Al≡MAO] with the distances r(Zr–μMe) = 2.38 Å and r(Al–μMe) = 2.28 Å. The following interaction of the μ‐Me contact ion pair ( d ) with AlMe3 results in a formation of the trimethylaluminum (TMA)‐separated ion pair ( e ) [Cp2Zr(μMe)2AlMe2]+–[MeMAO]– with r[Zr–(MeMAO)] equal to 4.58 Å. The calculated composition and structure of ion pairs ( d ) and ( e ) are consistent with the 13C NMR data for the species detected in the Cp2ZrMe2/MAO system. An interaction of the TMA‐separated ion pair ( e ) with ethylene results in the substitution of AlMe3 by C2H4 in a cationic part of the ion pair ( e ), and the following ethylene insertion into the Zr–Me bond. This reaction leads to formation of ion pair ( f ) of the composition [Cp2ZrCH2CH2CH3]+–[Me‐MAO]– named as the propyl‐separated ion pair. Ion pair ( f ) exhibits distance r[Zr–(MeMAO)] = 3.88 Å and strong Cγ‐agostic interaction of the propyl group with the Zr atom. We suppose this propyl‐separated ion pair ( f ) to be an active center for olefin polymerization. 相似文献
3.
Tae‐Jin Kim Sung‐Kwan Kim Beom‐Jun Kim Ho‐Jin Son Jong Sok Hahn Minserk Cheong Prof. Mariusz Mitoraj Dr. Monika Srebro Łukasz Piękoś Artur Michalak Prof. Sang Ook Kang Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(19):5630-5644
A series of mono‐, bis‐, and tris(phenoxy)–titanium(IV) chlorides of the type [Cp*Ti(2‐R? PhO)nCl3?n] (n=1–3; Cp*=pentamethylcyclopentadienyl) was prepared, in which R=Me, iPr, tBu, and Ph. The formation of each mono‐, bis‐, and tris(2‐alkyl‐/arylphenoxy) series was authenticated by structural studies on representative examples of the phenyl series including [Cp*Ti(2‐Ph? PhO)Cl2] ( 1 PhCl2 ), [Cp*Ti(2‐Ph? PhO)2Cl] ( 2 PhCl ), and [Cp*Ti(2‐Ph? PhO)3] ( 3 Ph ). The metal‐coordination geometry of each compound is best described as pseudotetrahedral with the Cp* ring and the 2‐Ph? PhO and chloride ligands occupying three leg positions in a piano‐stool geometry. The mean Ti? O distances, observed with an increasing number of 2‐Ph? PhO groups, are 1.784(3), 1.802(4), and 1.799(3) Å for 1 PhCl2 , 2 PhCl , and 3 Ph , respectively. All four alkyl/aryl series with Me, iPr, tBu, and Ph substituents were tested for ethylene homopolymerization after activation with Ph3C+[B(C6F5)4]? and modified methyaluminoxane (7% aluminum in isopar E; mMAO‐7) at 140 °C. The phenyl series showed much higher catalytic activity, which ranged from 43.2 and 65.4 kg (mmol of Ti?h)?1, than the Me, iPr, and tBu series (19.2 and 36.6 kg (mmol of Ti?h)?1). Among the phenyl series, the bis(phenoxide) complex of 2 PhCl showed the highest activity of 65.4 kg (mmol of Ti?h)?1. Therefore, the catalyst precursors of the phenyl series were examined by treating them with a variety of alkylating reagents, such as trimethylaluminum (TMA), triisobutylaluminum (TIBA), and methylaluminoxane (MAO). In all cases, 2 PhCl produced the most catalytically active alkylated species, [Cp*Ti(2‐Ph? PhO)MeCl]. This enhancement was further supported by DFT calculations based on the simplified model with TMA. 相似文献
4.
Secondary Hydroxyalkylphosphanes: Synthesis and Characterization of Mono‐, Bis‐ and Trisalkoxyphosphane‐substituted Zirconium Complexes and the Heterobimetallic Trinuclear Complex [Cp2Zr{O(CH2)3PHMes(AuCl)}2] The secondary hydroxyalkylphosphanes RPHCH2OH [R = 2,4,6‐Me3C6H2 (Mes) ( 1 ), 2,4,6‐iPr3C6H2 (Tipp) ( 2 )], 1‐AdPH‐2‐OH‐cyclo‐C6H10 ( 3 ) and RPH(CH2)3OH [R = Ph ( 4 ), Mes ( 5 ), Tipp ( 6 ), Cy ( 7 ), tBu ( 8 )] were obtained from primary phosphanes RPH2 and formaldehyde ( 1 , 2 ) or from LiPHR and cyclohexene oxide ( 3 ) or trimethylene oxide ( 4 ‐ 8 ). Starting from 5 or 7 and [CpR2ZrMe2] [CpR = C5EtMe4 (Cp°), C5H5 (Cp), C5MeH4 (Cp′)], the monoalkoxyphosphane‐substituted zirconocene complexes [CpR2Zr(Me){O(CH2)3PHMes}] [CpR = Cp° ( 9 ), Cp ( 10 )] were prepared. With [CpR2ZrCl2], the bisalkoxyphosphane‐substituted complexes [Cp′2Zr{O(CH2)3PHMes}2] ( 11 ) and [Cp2Zr{O(CH2)3PHCy}2] ( 12 ) are obtained, and with [TpRZrCl3], the trisalkoxyphosphane‐substituted zirconium complexes [TpRZr{O(CH2)3PHMes}3] [TpR = trispyrazolylborato (Tp) ( 13 ), TpR = tris(3,5‐dimethyl)pyrazolylborato (Tp*) ( 14 )] are prepared. The reaction of 5 with [AuCl(tht)] (tht = tetrahydrothiophene) yielded the mononuclear complex [AuCl{PHMes(CH2)3OH}] ( 15 ). The trinuclear complex [Cp2Zr{O(CH2)3PHMes(AuCl)}2] ( 16 ) was obtained from [Cp2ZrCl2] and 15 . Compounds 1 ‐ 16 were characterized spectroscopically (1H‐, 31P‐, 13C‐NMR; IR; MS) and compound 2 also by crystal structure determination. The bis‐ and trisalkoxyphosphane‐substituted complexes 11‐14 and 16 were obtained as mixtures of two diastereomers which could not be separated. 相似文献
5.
Shubhankar Kumar Bose K. Geetharani V. Ramkumar Shaikh M. Mobin Sundargopal Ghosh Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(48):13483-13490
Reaction of [CpnMCl4?x] (M=V: n=x=2; M=Nb: n=1, x=0) or [Cp*TaCl4] (Cp=η5‐C5H5, Cp*=η5‐C5Me5), with [LiBH4?thf] at ?70 °C followed by thermolysis at 85 °C in the presence of [BH3?thf] yielded the hydrogen‐rich metallaboranes [(CpM)2(B2H6)2] ( 1 : M=V; 2 : M = Nb) and [(Cp*Ta)2(B2H6)2] ( 3 ) in modest to high yields. Complexes 1 and 3 are the first structurally characterized compounds with a metal–metal bond bridged by two hexahydroborate (B2H6) groups forming a symmetrical complex. Addition of [BH3?thf] to 3 results in formation of a metallaborane [(Cp*Ta)2B4H8(μ‐BH4)] ( 4 ) containing a tetrahydroborate ligand, [BH4]?, bound exo to the bicapped tetrahedral cage [(Cp*Ta)2B4H8] by two Ta‐H‐B bridge bonds. The interesting structural feature of 4 is the coordination of the bridging tetrahydroborate group, which has two B? H bonds coordinated to the tantalum atoms. All these new metallaboranes have been characterized by mass, 1H, 11B, and 13C NMR spectroscopy and elemental analysis and the structural types were established unequivocally by crystallographic analysis of 1 – 4 . 相似文献
6.
《Polyhedron》1986,5(7):1259-1265
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. 相似文献
7.
Dr. Tyler K. Trefz Dr. Matthew A. Henderson Prof. Mikko Linnolahti Dr. Scott Collins Prof. J. Scott McIndoe 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(7):2980-2991
Electrospray‐ionization mass spectrometric studies of poly(methylaluminoxane) (MAO) in the presence of [Cp2ZrMe2], [Cp2ZrMe(Cl)], and [Cp2ZrCl2] in fluorobenzene (PhF) solution are reported. The results demonstrate that alkylation and ionization are separate events that occur at competitive rates in a polar solvent. Furthermore, there are significant differences in ion‐pair speciation that result from the use of metallocene dichloride complexes in comparison to alkylated precursors at otherwise identical Al/Zr ratios. Finally, the counter anions that form are dependent on the choice of precursor and Al/Zr ratio; halogenated aluminoxane anions [(MeAlO)x(Me3Al)y?z(Me2AlCl)zMe]? (z=1, 2, 3…?) are observed using metal chloride complexes and under some conditions may predominate over their non‐halogenated precursors [(MeAlO)x(Me3Al)yMe]?. Specifically, this halogenation process appears selective for the anions that form in comparison to the neutral components of MAO. Only at very high Al/Zr ratios is the same “native” anion distribution observed when using [Cp2ZrCl2] when compared with [Cp2ZrMe2]. Together, the results suggest that the need for a large excess of MAO when using metallocene dichloride complexes is a reflection of competitive alkylation vs. ionization, the persistence of unreactive, homodinuclear ion pairs in the case of [Cp2ZrCl2], as well as a change in ion pairing resulting from modification of the anions formed at lower Al/Zr ratios. Models for neutral precursors and anions are examined computationally. 相似文献
8.
Reactions of Group 4 Metallocenes with Monosubstituted Acetonitriles: Keteniminate Formation versus CC Coupling
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Lisanne Becker Dr. Martin Haehnel Dr. Anke Spannenberg Dr. Perdita Arndt Dr. Uwe Rosenthal 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(8):3242-3248
The reactions of the Group 4 metallocene dichlorides [Cp′2MCl2] ( 1 a : M=Ti, Cp′=Cp*=η5‐pentamethylcyclopentadienyl, 1 b : M=Zr, Cp′=Cp=η5‐cyclopentadienyl) with lithiated MesCH2?C?N gave [Cp*2TiCl(N=C=C(HMes))] ( 3 ; Mes=mesityl) in the case of 1 a . For compound 1 b , a nitrile–nitrile coupling resulted in a five‐membered bridge in 4 . The reaction of the metallocene alkyne complex [Cp*2Zr(η2‐Me3SiC2SiMe3)] ( 2 ) with PhCH2?C?N led in the first step to the unstable product [Cp*2Zr(η2‐Me3SiC2SiMe3)(NC?CH2Ph)] ( 5 ). After the elimination of the alkyne, a mixture of products was formed. By variation of the solvent and the reaction temperature, three compounds were isolated: a diazadiene complex 6 , a bis(keteniminate) complex 7 , and 8 with a keteniminate ligand and a five‐membered metallacycle. Subsequent variation of the Cp ligand and the metal center by using [Cp2Zr] and [Cp*2Ti] with Me3SiC2SiMe3 in the reactions with PhCH2?C?N gave complex mixtures. 相似文献
9.
Reactions of 2‐Substituted Pyridines with Titanocenes and Zirconocenes: Coupling versus Dearomatisation
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Dr. Fabian Reiß Dr. Kai Altenburger Dr. Lisanne Becker Kathleen Schubert Dr. Haijun Jiao Dr. Anke Spannenberg Dr. Dirk Hollmann Dr. Perdita Arndt Prof. Dr. Uwe Rosenthal 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(10):3361-3369
Reactions of group 4 metallocene sources with 2‐substituted pyridines were investigated to evaluate their coordination type between innocent and reductive dearomatisation as well as to probe the possibility for couplings. A dependence on the cyclopentadienyl ligands (Cp, Cp*), the metals (Ti, Zr), and the substrates (2‐phenyl‐, 2‐acetyl‐, and 2‐iminopyridine) was observed. While 2‐phenylpyridine is barely reactive, 2‐acetylpyridine reacts vigorously with the Cp‐substituted complexes and selectively with their Cp* analogues. With 2‐iminopyridine, in all cases selective reactions were observed. In the isolated [Cp2Ti], [Cp2Zr], and [Cp*2Zr] compounds the substrate coordinates by its pyridyl ring and the unsaturated side‐chain. Subsequently, the pyridine was dearomatised, which is most pronounced in the [Cp*2Zr] compounds. Using [Cp*2Ti] leads to the unexpected paramagnetic complexes [Cp*2TiIII(N,O‐acpy)] and [Cp*2TiIII(N,N′‐impy)]. This highlights the non‐innocent character of the pyridyl substrates. 相似文献
10.
Helena Brake Eugenia Peresypkina Alexander V. Virovets Martin Piesch Werner Kremer Lisa Zimmermann Christian Klimas Manfred Scheer 《Angewandte Chemie (International ed. in English)》2020,59(37):16241-16246
In a high‐yield one‐pot synthesis, the reactions of [Cp*M(η5‐P5)] (M=Fe ( 1 ), Ru ( 2 )) with I2 resulted in the selective formation of [Cp*MP6I6]+ salts ( 3 , 4 ). The products comprise unprecedented all‐cis tripodal triphosphino‐cyclotriphosphine ligands. The iodination of [Cp*Fe(η5‐As5)] ( 6 ) gave, in addition to [Fe(CH3CN)6]2+ salts of the rare [As6I8]2? (in 7 ) and [As4I14]2? (in 8 ) anions, the first di‐cationic Fe‐As triple decker complex [(Cp*Fe)2(μ,η5:5‐As5)][As6I8] ( 9 ). In contrast, the iodination of [Cp*Ru(η5‐As5)] ( 10 ) did not result in the full cleavage of the M?As bonds. Instead, a number of dinuclear complexes were obtained: [(Cp*Ru)2(μ,η5:5‐As5)][As6I8]0.5 ( 11 ) represents the first Ru‐As5 triple decker complex, thus completing the series of monocationic complexes [(CpRM)2(μ,η5:5‐E5)]+ (M=Fe, Ru; E=P, As). [(Cp*Ru)2As8I6] ( 12 ) crystallizes as a racemic mixture of both enantiomers, while [(Cp*Ru)2As4I4] ( 13 ) crystallizes as a symmetric and an asymmetric isomer and features a unique tetramer of {AsI} arsinidene units as a middle deck. 相似文献
11.
A series of binuclear complexes [{Cp*Ir(OOCCH2COO)}2(pyrazine)] ( 1 b ), [{Cp*Ir(OOCCH2COO)}2(bpy)] ( 2 b ; bpy=4,4′‐bipyridine), [{Cp*Ir(OOCCH2COO)}2(bpe)] ( 3 b ; bpe=trans‐1,2‐bis(4‐pyridyl)ethylene) and tetranuclear metallamacrocycles [{(Cp*Ir)2(OOC‐C?C‐COO)(pyrazine)}2] ( 1 c ), [{(Cp*Ir)2(OOC‐C?C‐COO)(bpy)}2] ( 2 c ), [{(Cp*Ir)2(OOC‐C?C‐COO)(bpe)}2] ( 3 c ), and [{(Cp*Ir)2[OOC(H3C6)‐N?N‐(C6H3)COO](pyrazine)}2] ( 1 d ), [{(Cp*Ir)2[OOC(H3C6)‐N?N‐(C6H3)COO](bpy)}2] ( 2 d ), [{(Cp*Ir)2[OOC(H3C6)‐N?N‐(C6H3)COO](bpe)}2] ( 3 d ) were formed by reactions of 1 a – 3 a {[(Cp*Ir)2(pyrazine)Cl2] ( 1 a ), [(Cp*Ir)2(bpy)Cl2] ( 2 a ), and [(Cp*Ir)2(bpe)Cl2] ( 3 a )} with malonic acid, fumaric acid, or H2ADB (azobenzene‐4,4′‐chcarboxylic acid), respectively, under mild conditions. The metallamacrocycles were directly self‐assembled by activation of C? H bonds from dicarboxylic acids. Interestingly, after exposure to UV/Vis light, 3 c was converted to [2+2] cycloaddition complex 4 . The molecular structures of 2 b , 1 c , 1 d , and 4 were characterized by single‐crystal x‐ray crystallography. Nanosized tubular channels, which may play important roles for their stability, were also observed in 1 c , 1 d , and 4 . All complexes were well characterized by 1H NMR and IR spectroscopy, as well as elemental analysis. 相似文献
12.
Ravi Yadav Thomas Simler Bhupendra Goswami Christoph Schoo Ralf Kppe Subhayan Dey Peter W. Roesky 《Angewandte Chemie (International ed. in English)》2020,59(24):9443-9447
A route to directly access mixed Al–Fe polyphosphide complexes was developed. The reactivity of pentaphosphaferrocene, [Cp*Fe(η5‐P5)] (Cp*=C5Me5), with two different low‐valent aluminum compounds was investigated. The steric and electronic environment around the [AlI] centre are found to be crucial for the formation of the resulting Al–Fe polyphosphides. Reaction with the sterically demanding [Dipp‐BDIAlI] (Dipp‐BDI={[2,6‐iPr2C6H3NCMe]2CH}?) resulted in the first Al‐based neutral triple‐decker type polyphosphide complex. For [(Cp*AlI)4], an unprecedented regioselective insertion of three [Cp*AlIII]2+ moieties into two adjacent P?P bonds of the cyclo‐P5 ring of [Cp*Fe(η5‐P5)] was observed. The regioselectivity of the insertion reaction could be rationalized by isolating an analogue of the reaction intermediate stabilized by a strong σ‐donor carbene. 相似文献
13.
A series of half‐sandwich rhodium‐based metallamacrocycles with tetra‐ and hexanuclearities have been synthesized. They are assembled by linking the deprotonated 2,4‐diacetyl‐5‐hydroxy‐5‐methyl‐3‐(3‐pyridinyl)cyclohexanone (HL) ligand in the presence of counteranions. When the counteranion was the tetrahedral BF4? ion, tetranuclear metallamacrocycle [(Cp*RhL)4][BF4]4 ( 1 d ) was formed. However, the larger OTf?, PF6?, and SbF6? counterions favored the formation of hexanuclear metallamacrocycles [(Cp*RhL)6?2OTf][OTf]4 ( 1 a ), [(Cp*RhL)6?2PF6][PF6]4 ( 1 b ), and [(Cp*RhL)6?2SbF6][SbF6]4 ? 6CH3CN ( 1 c ) when the reactions were performed under the same conditions. Single‐crystal X‐ray analysis indicated that, in the solid state, two counteranions were encapsulated in each belt‐like host molecule of hexanuclear metallamacrocycles 1 a , b , and c . Based on the results of 1H NMR analysis in methanol, the nuclearities of 1 a – c and the two encapsulated anions in each molecular cavity were maintained in solution. In addition, tetranuclear metallamacrocycle 1 d was converted into the hexanuclear metallamacrocycles 1 a′ , b , and c after addition of the appropriate anion as its [NBu4]+ salt. The compound 1 a′ was characterized by single‐crystal X‐ray diffraction to have the formula [(Cp*RhL)6?2OTf][BF4]4 ? 2M eOH ? 2H2O. From the interconversion of the hexanuclear metallamacrocycles, we have concluded that the hexanuclear belt‐like host in 1 a – c has an clear selectivity for larger anions, in the sequence SbF6?≈PF6?>OTf?>BF4?>Cl?. 相似文献
14.
Prof. Robert D. Robinson Jr. Dr. Werner Kaminsky Prof. Jeremiah J. Scepaniak 《欧洲无机化学杂志》2023,26(27):e202300369
The complexes Cp(MeIm)IrI2 and CpMe4(MeIm)IrCl2 have been prepared and subsequently methylated to form Cp(MeIm)IrMe2 and CpMe4(MeIm)IrMe2 (Cp=η5-C5H5, CpMe4=η5-C5HMe4, MeIm=1,3-dimethylimidazol-2-ylidene). We attempted unsuccessfully to use the dimethyl complexes to study C−D bond activation via methyl-group abstraction. Protonation with one equivalent of a weak acid, such as 2,6-dimethylpyridinium chloride, affords methane and IrIII methyl chloride complexes. 1H-NMR experiments show addition of pyridinium [BArF20]− (BArF20=[B(C6F5)4]−) to the dimethyl species forms [Cp(MeIm)IrMe(py)]+[BArF20]− (py=pyridine) or [CpMe4(MeIm)IrMe(py)]+[BArF20]− respectively, alongside methane, while use of the [BArF20]− salts of more bulky 2,6-dimethylpyridinium and 2,6-di-tert-butylpyridinium gave an intractable mixture. Likewise, the generation of 16 e− species [CpMe4(MeIm)IrMe]+[BArF20]− or [Cp(MeIm)IrMe]+[BarF20]− at low temperature using 2,6-dimethylpyridinium or 2,6-di-tert-butylpyridinium in thawing C6D6 or toluene-d8 formed an intractable mixture and did not lead to C−D bond activation. X-ray structures of several IrIII complexes show similar sterics as that found for the previously reported Cp* analogue. 相似文献
15.
Runhai Chen Guorui Qin Shihui Li Alison J. Edwards Ross O. Piltz Iker Del Rosal Laurent Maron Dongmei Cui Jianhua Cheng 《Angewandte Chemie (International ed. in English)》2020,59(28):11250-11255
Hydrogenolysis of alkyl‐substituted cyclopentadienyl (CpR) ligated thorium tribenzyl complexes [(CpR)Th(p‐CH2‐C6H4‐Me)3] ( 1 – 6 ) afforded the first examples of molecular thorium trihydrido complexes [(CpR)Th(μ‐H)3]n (CpR=C5H2(tBu)3 or C5H2(SiMe3)3, n=5; C5Me4SiMe3, n=6; C5Me5, n=7; C5Me4H, n=8; 7 – 10 and 12 ) and [(Cp#)12Th13H40] (Cp#=C5H4SiMe3; 13 ). The nuclearity of the metal hydride clusters depends on the steric profile of the cyclopentadienyl ligands. The hydrogenolysis intermediate, tetra‐nuclear octahydrido thorium dibenzylidene complex [(Cpttt)Th(μ‐H)2]4(μ‐p‐CH‐C6H4‐Me)2 (Cpttt=C5H2(tBu)3) ( 11 ) was also isolated. All of the complexes were characterized by NMR spectroscopy and single‐crystal X‐ray analysis. Hydride positions in [(CpMe4)Th(μ‐H)3]8 (CpMe4=C5Me4H) were further precisely confirmed by single‐crystal neutron diffraction. DFT calculations strengthen the experimental assignment of the hydride positions in the complexes 7 to 12 . 相似文献
16.
The reaction of the neutral carborane C2B9H13 with Cp*M(CH3)3 (M = Zr (a), Hf (b); Cp* = η5-C5Me5) yields [Cp(C2B9H11)M(CH3)]n (3a, b). Complexes 3a, b form THF adducts Cp*(C2B9H11)M(CH3)(THF) 4, insert 2-butyne to yield Cp*(C2B9H11)M{C(Me=CMe2} 5, and undergo methane elimination upon thermolysis to yield methylene-bridged complexes [Cp*(C2B9H11)M]2(μ-CH2) (6). These chemical studies, and companion structural and theoretical studies establish that 3a, b are neutral analogues of the cationic Cp2M(R)+ species (1; Cp = η5-C5H5) and Cp2M(R)(L)+ (2) which are believed to be active in Cp2MX2-based Ziegler catalysts. Despite the lower metal charge, 3–6 exhibit characteristic “electrophilic metal alkyl” properties including agostic M-H-C and M-H-B interactions, high insertion and intramolecular C-H activation reactivity, and high ethylene polymerization and propene oligomerization activity. These observations suggest that the key requirement for high insertion/polymerization activity in metallocene systems is high metal unsaturation (i.e. two empty metal-centered orbitals) rather than charge. 相似文献
17.
Synthesis, structure, and reactivity of carboranylamidinate‐based half‐sandwich iridium and rhodium complexes are reported for the first time. Treatment of dimeric metal complexes [{Cp*M(μ‐Cl)Cl}2] (M=Ir, Rh; Cp*=η5‐C5Me5) with a solution of one equivalent of nBuLi and a carboranylamidine produces 18‐electron complexes [Cp*IrCl(CabN‐DIC)] ( 1 a ; CabN‐DIC=[iPrN?C(closo‐1,2‐C2B10H10)(NHiPr)]), [Cp*RhCl(CabN‐DIC)] ( 1 b ), and [Cp*RhCl(CabN‐DCC)] ( 1 c ; CabN‐DCC=[CyN?C(closo‐1,2‐C2B10H10)(NHCy)]). A series of 16‐electron half‐sandwich Ir and Rh complexes [Cp*Ir(CabN′‐DIC)] ( 2 a ; CabN′‐DIC=[iPrN?C(closo‐1,2‐C2B10H10)(NiPr)]), [Cp*Ir(CabN′‐DCC)] ( 2 b , CabN′‐DCC=[CyN?C(closo‐1,2‐C2B10H10)(NCy)]), and [Cp*Rh(CabN′‐DIC)] ( 2 c ) is also obtained when an excess of nBuLi is used. The unexpected products [Cp*M(CabN,S‐DIC)], [Cp*M(CabN,S‐DCC)] (M=Ir 3 a , 3 b ; Rh 3 c , 3 d ), formed through BH activation, are obtained by reaction of [{Cp*MCl2}2] with carboranylamidinate sulfides [RN?C(closo‐1,2‐C2B10H10)(NHR)]S? (R=iPr, Cy), which can be prepared by inserting sulfur into the C? Li bond of lithium carboranylamidinates. Iridium complex 1 a shows catalytic activities of up to 2.69×106 gPNB ${{\rm{mol}}_{{\rm{Ir}}}^{ - {\rm{1}}} }Synthesis, structure, and reactivity of carboranylamidinate-based half-sandwich iridium and rhodium complexes are reported for the first time. Treatment of dimeric metal complexes [{Cp*M(μ-Cl)Cl}(2)] (M = Ir, Rh; Cp* = η(5)-C(5)Me(5)) with a solution of one equivalent of nBuLi and a carboranylamidine produces 18-electron complexes [Cp*IrCl(Cab(N)-DIC)] (1?a; Cab(N)-DIC = [iPrN=C(closo-1,2-C(2)B(10)H(10))(NHiPr)]), [Cp*RhCl(Cab(N)-DIC)] (1?b), and [Cp*RhCl(Cab(N)-DCC)] (1?c; Cab(N)-DCC = [CyN=C(closo-1,2-C(2)B(10)H(10))(NHCy)]). A series of 16-electron half-sandwich Ir and Rh complexes [Cp*Ir(Cab(N')-DIC)] (2?a; Cab(N')-DIC = [iPrN=C(closo-1,2-C(2)B(10)H(10))(NiPr)]), [Cp*Ir(Cab(N')-DCC)] (2?b, Cab(N')-DCC = [CyN=C(closo-1,2-C(2)B(10)H(10)(NCy)]), and [Cp*Rh(Cab(N')-DIC)] (2?c) is also obtained when an excess of nBuLi is used. The unexpected products [Cp*M(Cab(N,S)-DIC)], [Cp*M(Cab(N,S)-DCC)] (M = Ir 3?a, 3?b; Rh 3?c, 3?d), formed through BH activation, are obtained by reaction of [{Cp*MCl(2)}(2)] with carboranylamidinate sulfides [RN=C(closo-1,2-C(2)B(10)H(10))(NHR)]S(-) (R = iPr, Cy), which can be prepared by inserting sulfur into the C-Li bond of lithium carboranylamidinates. Iridium complex 1?a shows catalytic activities of up to 2.69×10(6) g(PNB) mol(Ir)(-1) h(-1) for the polymerization of norbornene in the presence of methylaluminoxane (MAO) as cocatalyst. Catalytic activities and the molecular weight of polynorbornene (PNB) were investigated under various reaction conditions. All complexes were fully characterized by elemental analysis and IR and NMR spectroscopy; the structures of 1?a-c, 2?a, b; and 3?a, b, d were further confirmed by single crystal X-ray diffraction. 相似文献
18.
Reactivity of TpMe2‐Supported Yttrium Alkyl Complexes toward Aromatic N‐Heterocycles: Ring‐Opening or CC Bond Formation Directed by CH Activation
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Dr. Weiyin Yi Prof. Dr. Jie Zhang Shujian Huang Prof. Dr. Linhong Weng Prof. Dr. Xigeng Zhou 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(3):867-876
Unusual chemical transformations such as three‐component combination and ring‐opening of N‐heterocycles or formation of a carbon–carbon double bond through multiple C–H activation were observed in the reactions of TpMe2‐supported yttrium alkyl complexes with aromatic N‐heterocycles. The scorpionate‐anchored yttrium dialkyl complex [TpMe2Y(CH2Ph)2(THF)] reacted with 1‐methylimidazole in 1:2 molar ratio to give a rare hexanuclear 24‐membered rare‐earth metallomacrocyclic compound [TpMe2Y(μ‐N,C‐Im)(η2‐N,C‐Im)]6 ( 1 ; Im=1‐methylimidazolyl) through two kinds of C–H activations at the C2‐ and C5‐positions of the imidazole ring. However, [TpMe2Y(CH2Ph)2(THF)] reacted with two equivalents of 1‐methylbenzimidazole to afford a C–C coupling/ring‐opening/C–C coupling product [TpMe2Y{η3‐(N,N,N)‐N(CH3)C6H4NHCH?C(Ph)CN(CH3)C6H4NH}] ( 2 ). Further investigations indicated that [TpMe2Y(CH2Ph)2(THF)] reacted with benzothiazole in 1:1 or 1:2 molar ratio to produce a C–C coupling/ring‐opening product {(TpMe2)Y[μ‐η2:η1‐SC6H4N(CH?CHPh)](THF)}2 ( 3 ). Moreover, the mixed TpMe2/Cp yttrium monoalkyl complex [(TpMe2)CpYCH2Ph(THF)] reacted with two equivalents of 1‐methylimidazole in THF at room temperature to afford a trinuclear yttrium complex [TpMe2CpY(μ‐N,C‐Im)]3 ( 5 ), whereas when the above reaction was carried out at 55 °C for two days, two structurally characterized metal complexes [TpMe2Y(Im‐TpMe2)] ( 7 ; Im‐TpMe2=1‐methyl‐imidazolyl‐TpMe2) and [Cp3Y(HIm)] ( 8 ; HIm=1‐methylimidazole) were obtained in 26 and 17 % isolated yields, respectively, accompanied by some unidentified materials. The formation of 7 reveals an uncommon example of construction of a C?C bond through multiple C–H activations. 相似文献
19.
Dr. Katharina Kaleta Frank Strehler Dr. Alexander Hildebrandt Dr. Torsten Beweries Dr. Perdita Arndt Dr. Tobias Rüffer Dr. Anke Spannenberg Prof. Dr. Heinrich Lang Prof. Dr. Uwe Rosenthal 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(40):12672-12680
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. 相似文献
20.
Igor L. Fedushkin Prof. Dr. Anton N. Lukoyanov Dr. Alexandra N. Tishkina Dipl.‐Chem. Georgy K. Fukin Dr. Konstantin A. Lyssenko Prof. Dr. Markus Hummert Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(25):7563-7571
The reduction of digallane [(dpp‐bian)Ga? Ga(dpp‐bian)] ( 1 ) (dpp‐bian=1,2‐bis[(2,6‐diisopropylphenyl)imino]acenaphthene) with lithium and sodium in diethyl ether, or with potassium in THF affords compounds featuring the direct alkali metal–gallium bonds, [(dpp‐bian)Ga? Li(Et2O)3] ( 2 ), [(dpp‐bian)Ga? Na(Et2O)3] ( 3 ), and [(dpp‐bian)Ga? K(thf)5] ( 7 ), respectively. Crystallization of 3 from DME produces compound [(dpp‐bian)Ga? Na(dme)2] ( 4 ). Dissolution of 3 in THF and subsequent crystallization from diethyl ether gives [(dpp‐bian)Ga? Na(thf)3(Et2O)] ( 5 ). Ionic [(dpp‐bian)Ga]?[Na([18]crown‐6)(thf)2]+ ( 6 a ) and [(dpp‐bian)Ga]?[Na(Ph3PO)3(thf)]+ ( 6 b ) were obtained from THF after treatment of 3 with [18]crown‐6 and Ph3PO, respectively. The reduction of 1 with Group 2 metals in THF affords [(dpp‐bian)Ga]2M(thf)n (M=Mg ( 8 ), n=3; M=Ca ( 9 ), Sr ( 10 ), n=4; M=Ba ( 11 ), n=5). The molecular structures of 4 – 7 and 11 have been determined by X‐ray crystallography. The Ga? Na bond lengths in 3 – 5 vary notably depending on the coordination environment of the sodium atom. 相似文献