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1.
The synthesis of the germylene phosphane adduct (C2F5)2Ge?PMe3 is described. Starting from (C2F5)3GeH in an excess of PMe3, heating was applied, whereupon reductive elimination of C2F5H occurred. The molecular structure was ascertained by X‐ray diffraction and compared with information obtained by quantum chemical methods. The ligand properties were derived by studying the IR spectrum of the nickel(0) complex [Ni(CO)3{Ge(C2F5)2(PMe3)}] in the CO region. (C2F5)2Ge?PMe3 turned out to be a π‐accepting ligand comparable to PMe3, in terms of Tolman's electronic parameter. Furthermore a [2+4] cycloaddition reaction with 2,3‐dimethyl‐1,3‐butadiene, and σ‐bond insertion reactions were recorded. Activation of the C?Cl bond in dichloromethane gives rise to the formation of the phosphonium ylide complex [(C2F5)2Cl2Ge‐CH2PMe3], which was fully characterized by X‐ray diffraction.  相似文献   

2.
The reaction of the salts K[Ru(CO)3(PMe3)(SiR3)] (R=Me, Et) with Br2BDur or Cl2BDur (Dur=2,3,5,6‐Me4C6H) leads to both boryl and borylene complexes of divalent ruthenium, the former through simple salt elimination and the latter through subsequent CO loss and 1,2‐halide shift. The balance of products can be altered by varying the reaction conditions; boryl complexes can be favored by the addition of CO, and borylene complexes by removal of CO under vacuum. All of these products are in competition with the corresponding (aryl)(halo)(trialkylsilyl)borane, a reductive elimination product. The RuII borylene products and the mechanisms that form them are distinctly different from the analogous reactions with iron, which lead to low‐valent borylene complexes, highlighting fundamental differences in oxidation state preferences between iron and ruthenium.  相似文献   

3.
The reaction of trans-I(CO)4WCNEt2 (I) with a slight excess of PMe3 results in the replacement of one carbonyl group to give mer-I(CO)3(PMe3)WCNEt2 (II). Complex II reacts at room temperature with additional PMe3 under CO replacement to give a mixture of cis- and trans-dicarbonyl-I(CO)2(PMe3)2WCNEt2 (III, IV). Complexes III and IV, which can be separated by column chromatography, isomerize slowly at room temperature, the thermodynamic equilibrium favouring the more stable trans complex IV. The cis isomer III can be obtained from I(CO)2py2WCNEt2 (V) and PMe3. Another CO ligand can be eliminated from III or IV by an excess of PMe3 in boiling hexane and gives mer-I(CO)(PMe3)3WCNEt2 (VI). Moreover complex VI can be prepared by oxidative decarbonylation from III or IV by iodine and subsequent reduction of the intermediate, an isolable, seven-coordinated carbyne complex formulated as (I)3(CO)(PMe3)2WCNEt2 (VII), by two equivalents of PMe3.  相似文献   

4.
The sequential reaction of the amino(trimethylsilyl)carbene complex [(CO)5W=C(NH2)C≡CSiMe3] ( 1 ) with nBuLi and [I‐Fe(CO)2Cp] affords the C(carbene)‐N bridged heterobinuclear complex [(CO)5W=C{NHFe(CO)2Cp}C≡CSiMe3] ( 2 ). Desilylation of 1 is achieved by treatment with KF in THF/MeOH. From the reaction of the resulting complex [(CO)5W=C(NH2)C≡CH] ( 3 ) with nBuLi and [I‐Fe(CO)2Cp] two binuclear WFe compounds in a ratio of approximately 1:1 are obtained: the C(carbene)‐C≡C bridged complex 4 and the C(carbene)‐N bridged complex 5 . Repetition of the deprotonation/metallation sequence yields the trinuclear WFe2 complex 6 . One Fe(CO)2Cp fragment in 6 is bonded to the amino group and the other one to the terminal carbon atom of the ethynyl substituent. The analogous reaction of 3 with nBuLi and [Br‐Ni(PMe2Ph)2Mes] gives a ca. 1:1 mixture of two heterobinuclear complexes ( 7 and 8 ). Complex 7 is bridged by the C(carbene)‐C≡C and complex 8 by the C(carbene)‐N fragment. Subsequent reaction of 7 with BuLi and [Br‐Ni(PMe2Ph)2Mes] finally affords the trinuclear WNi2 complex 9 related to 6 . The solid‐state structure of 2 is established by an X‐ray diffraction analysis. The spectroscopic data of the bi‐ and trinuclear complexes indicate electronic communication between the metal centers through the bridging group.  相似文献   

5.
The dihaptoiminoacyl complex [Fe(CO)2 (PMe3)22CMeNCMe3)]+ I? was obtained by reaction of [Fe(CO)2(PMe3)2 MeI] and tertbutylisocyanide. The structure of the complex was determined by an X-ray structure analysis.  相似文献   

6.
Titanacyclopentadienes, prepared from [Cp2TiBu2] and either two equivalents of an alkyne or a diyne, were treated with PMe3 (3 equiv) at 50 °C for 3 h and then with azobenzene at room temperature for 12 h to give 4,5,6‐trisubstituted indene derivatives with the loss of one substituent in good yields. This reaction contrasts sharply with our previously reported reaction for the formation of 4,5,6,7‐tetrasubstituted indene derivatives without the loss of substituents by the treatment of titanacyclopentadienes with azobenzene without PMe3. 13C NMR spectroscopy of the product derived from a 13C‐enriched complex revealed that the five carbon atoms originating from a Cp ligand were arranged linearly in the trisubstituted indene derivatives, in contrast to the 4,5,6,7‐tetrasubsituted indene derivatives, in which the corresponding five carbon atoms are arranged in a ring.  相似文献   

7.
A detailed characterization of a close synthetic model of the [2 Fe]H subcluster in the [FeFe] hydrogenase active site is presented. It contains the full primary coordination sphere of the CO‐inhibited oxidized state of the enzyme including the CN? ligands and the azadithiolate (adt) bridge, [((μ‐S? CH2)2NR)Fe2(CO)4(CN)2]2?, R=CH2CH2SCH3. The electronic structure of the model complex in its FeIFeII state was investigated by means of density functional theory (DFT) calculations and Fourier transform infrared (FTIR) spectroscopy. By using a combination of continuous‐wave (CW) electron paramagnetic resonance (EPR) and hyperfine sublevel correlation (HYSCORE) experiments as well as DFT calculations, it is shown that, for this complex, the spin density is delocalized over both iron atoms. Interestingly, we found that the nitrogen hyperfine coupling, which represents the interaction between the unpaired electron and the nitrogen at the dithiolate bridge, is slightly larger than that in the analogous complex in which the CN? ligands are replaced with PMe3 ligands. This reveals, first, that the CN?/PMe3 ligands coordinated to the iron core are electronically coupled to the amine in the adt bridge. Second, the CN? ligands in this complex are somewhat stronger σ‐donor ligands than the PMe3 ligand, and thereby enable more spin density to be transferred from the Fe core to the adt unit, which might in turn affect the reactivity of the bridging amine.  相似文献   

8.
The N–H bond activation product [PNP]‐FeI(PMe3)2 ( 2 ) was obtained at room temperature by the reaction of diphosphinito [PNP] pincer ligand ((Ph2P(C6H4))2NH ( 1 )) with Fe(PMe3)4. Treatment of 1 with Co(PMe3)4, CoCl(PMe3)3 and CoMe(PMe3)4 afforded the same N–H bond activation product [PNP]‐CoI(PMe3)2 ( 3 ). In order to have a better understanding of the mechanism of formation of 3 , in situ IR and 1H NMR spectroscopic investigations were conducted.The reaction of 1 with Ni(PMe3)4 afforded the ligand replacement complex 4 while a [PNP]‐NiIIMe complex 5 was obtained via deprotonation through the reaction of 1 with NiMe2(PMe3)3. The molecular structures of 2 – 4 were confirmed by X‐ray diffraction analysis.  相似文献   

9.
A general approach to the first compounds that contain rhenium–germanium triple and double bonds is reported. Heating [ReCl(PMe3)5] ( 1 ) with the arylgermanium(II) chloride GeCl(C6H3‐2,6‐Trip2) ( 2 ; Trip=2,4,6‐triisopropylphenyl) results in the germylidyne complex mer‐[Cl2(PMe3)3Re?Ge? C6H3‐2,6‐Trip2] ( 4 ) upon PMe3 elimination. An equilibrium that is dependent on the PMe3 concentration exists between complexes 1 and 4 . Removal of the volatile PMe3 shifts the equilibrium towards complex 4 , whereas treatment of 4 with an excess of PMe3 gives a 1:1 mixture of 1 and the PMe3 adduct of 2 , GeCl(C6H3‐2,6‐Trip2)(PMe3) ( 2 ‐PMe3). Adduct 2 ‐PMe3 can be selectively obtained by addition of PMe3 to chlorogermylidene 2 . The NMR spectroscopic data for 2 ‐PMe3 indicate an equilibrium between 2 ‐PMe3 and its dissociation products, 2 and PMe3, which is shifted far towards the adduct site at ambient temperature. NMR spectroscopic monitoring of the reaction of complex 1 with 2 and the reaction of complex 4 with PMe3 revealed the formation of two key intermediates, which were identified to be the chlorogermylidene complexes cis/trans‐[Cl(PMe3)4Re?Ge(Cl)C6H3‐2,6‐Trip2] (cis/trans‐ 3 ) by using NMR spectroscopy. Labile chlorogermylidene complexes cis/trans‐ 3 can be also generated from trans‐[Cl(PMe3)4Re?Ge? C6H3‐2,6‐Trip2]BPh4 ( 9 ) and (nBu4N)Cl at low temperature, and decompose at ambient temperature to give a mixture of complexes 1 and 4 . Complex 4 reacts with LiI to give the diiodido derivative mer‐[I2(PMe3)3Re?Ge? C6H3‐2,6‐Trip2] ( 5 ), which undergoes a metathetical iodide/hydride exchange with Na(BEt3H) to give the dihydrido germylidyne complex mer‐[H2(PMe3)3Re?Ge? C6H3‐2,6‐Trip2] ( 6 ). Carbonylation of 4 induces a chloride migration from rhenium to the germanium atom to afford the chlorogermylidene complex mer‐[Cl(CO)(PMe3)3Re?Ge(Cl)C6H3‐2,6‐Trip2] ( 7 ). Similarly, MeNC converts complex 4 into the methylisocyanide analogue mer‐[Cl(MeNC)(PMe3)3Re?Ge(Cl)C6H3‐2,6‐Trip2] ( 8 ). Chloride abstraction from 4 by NaBPh4 in the presence of PMe3 gives the cationic germylidyne complex trans‐[Cl(PMe3)4Re?Ge? C6H3‐2,6‐Trip2]BPh4 ( 9 ). Heating complex 4 with cis‐[Mo(PMe3)4(N2)2] induces a germylidyne ligand transfer from rhenium to molybdenum to afford the germylidyne complex trans‐[Cl(PMe3)4Mo?Ge? C6H3‐2,6‐Trip2] ( 10 ). All new compounds were fully characterized and their molecular structures studied by X‐ray crystallography, which led to the first experimentally determined Re? Ge triple‐ and double‐bond lengths.  相似文献   

10.
The reaction of fac‐[Re(bipy)(CO)3(PMe3)][OTf] (bipy=2,2′‐bipyridine) with KN(SiMe3)2 affords two neutral products: cis,trans‐[Re(bipy)(CO)2(CN)(PMe3)], and a thermally unstable compound, which features a new C?C bond between a P‐bonded methylene group (from methyl group deprotonation) and the C6 position of bipy. The solid‐state structures of more stable 1,2‐bis[(2,6‐diisopropylphenyl)imino]acenaphthene analogs, resulting from the deprotonation of PMe3, PPhMe2, and PPh2Me ligands, are determined by X‐ray diffraction.  相似文献   

11.
The (nitro)(N‐methyldithiocarbamato)(trimethylphospane)nickel(II), [Ni(NO2)(S2CNHMe)(PMe3)] complex catalyses efficiently the O‐atom transfer reactions to CO and acetylene. Energetically feasible sequence of elementary steps involved in the catalytic cycle of the air oxidation of CO and acetylene are proposed promoted by the Ni(NO2)(S2CNHMe)(PMe3)] ↔ Ni(NO2)(S2CNHMe)(PMe3) redox couple using DFT methods both in vacuum and dichloromethane solutions. The catalytic air oxidation of HC≡CH involves formation of a five‐member metallacycle intermediate, via a [3 + 2] cyclo‐addition reaction of HC≡CH to the Ni‐N = O moiety of the Ni(NO2)(S2CNHMe)(PMe3)] complex, followed by a β H‐atom migration toward the Cα carbon atom of the coordinated acetylene and release of the oxidation product (ketene). The geometric and energetic reaction profile for the reversible [Ni( ‐NO2)(S2CNHMe)(PMe3)] [Ni( ‐ONO)(S2CNHMe)(PMe3)] linkage isomerization has also been modeled by DFT calculations. © 2017 Wiley Periodicals, Inc.  相似文献   

12.
Alternative Ligands. XXXVI. Novel Rhodium(I) Complexes with Donor/Acceptor Chelating Ligands In order to generate metal base/Lewis‐acid interactions in rhodium(I) phosphane complexes the binuclear complex [Rh(CO)2Cl]2 was reacted in benzene with dipod ligands of the type R2M′(OCH2PMe2)x(CH2CH2PMe2)2–x (R = F, Me; M′ = Si, Ge; x = 0–2) using the Ziegler dilution principle with the aim to produce mononuclear compounds in which with formation of five‐membered chelate rings in principle Rh → M′ contacts are possible. The reactions of ligands 1 – 7 (Table 1) with [Rh(CO)2Cl]2 proceed under CO elimination and, in spite of large turnovers, lead to a variety of products 8 – 14 (Table 1), in case of 11 , 13 and 14 accompanied by degradation of the corresponding ligands. Intact ligands are present in the 16‐membered rings of the binuclear complexes 8 – 10 and 12 , for which, due to the molecular structure, Rh → M′ interactions can be excluded. In the reaction of Me2Si(OCH2PMe2)2 ( 4 ) with [Rh(CO)2Cl]2 the unusual binuclear system 11 with a central Rh2O2 four‐membered ring and two RhO(SiMe2OCH2PMe2) six‐membered rings is formed. Small amounts of the mononuclear compounds Rh(CO)Cl(Me2PCH2OH)2 ( 13 ) and Rh(CO)Cl3(Me2PCH2OH)2 ( 14 ), respectively, are obtained in crystalline form from the reaction mixtures of [Rh(CO)2Cl]2 with Me2Ge(OCH2PMe2)(CH2CH2PMe2) ( 6 ) or Me2Ge(OCH2PMe2)2 ( 7 ). The new complexes were characterized by analytic (C, H), spectroscopic (NMR, IR, MS) and, except for 12 , by single crystal structural analyses.  相似文献   

13.
[Ru(CO)4PMe3] reacts with MeI to give fac-[Ru(CO)3(PMe3)(Me)I]. The latter reacts with PMe3 to give a mixture of the three isomers of cis-bis(trimethylphosphine)-cis-dicarbonyl acetyl iodide [Ru(CO)2(PMe3)2(COMe)I]. Decarbonylation of the mixture gives only the trans-bis(trimethylphosphine)-cis-dicarbonyl methyl iodide complex [Ru(CO)2(PMe3)2MeI], which was also prepared by oxidative addition of MeI to [Ru(CO)3(PMe3)2].  相似文献   

14.
The novel hydridocobalt(III) complex [mer-Co(H)(SPh)2(PMe3)3] (1) was prepared by reaction of thiophenol with [Co(PMe3)3Cl], [Co(PMe3)4] and [Co(PMe3)4Me]. A dinuclear cobalt dithiophenolato complex [Co(PMe3)2(SPh)]2 (2) was obtained from the reaction of thiophenol with [Co(PMe3)4Me]. Reaction of 1 with iodomethane afforded complex [Co(PMe3)3(I)2] (3). Reaction of complex 2 with carbon monoxide gave a mononuclear dicarbonyl cobalt(I) complex [Co(PMe3)3(CO)2(SPh)] (4). The crystal structures of 1-4 were determined by X-ray diffraction. Formation mechanism of 1 is discussed.  相似文献   

15.
The complexes C5H5Rh(PMe3)CS2(II) and C5H5Rh(PMe2Ph)CS2(III) are formed in excellent yields in the reaction of C5H5Rh(C2H4)PR3(PR3 = PMe3, PMe2Ph) with CS2 in benzene. The CS2 ligand in II and III is dihapto-bonded and at least in III is rigid. II reacts with Cr(CO)5THF and C5H5Mn(CO)2THF to give the binuclear complexes C5H5(PMe3)Rh(SCS)Cr(CO)5 (IV) and C5H5- (PMe3)Rh(SCS)Mn(CO)2C5H5 (V) in which the CS2 molecule bridges two different metal atoms. In the reaction of C5H5Rh(C2H4)PMe3 and CS2 under certain conditions a second product of C5H5Rh(PMe3)C2S4 (VI) is formed. The cyrstal structure shows that in this complex a five-membered RhSCSC heterocyclic ring is present.  相似文献   

16.
The equilibrium geometries and bond dissociation energies of 16‐valence‐electron(VE) complexes [(PMe3)2Cl2M(E)] and 18‐VE complexes [(PMe3)2(CO)2M(E)] with M=Fe, Ru, Os and E=C, Si, Ge, Sn were calculated by using density functional theory at the BP86/TZ2P level. The nature of the M? E bond was analyzed with the NBO charge decomposition analysis and the EDA energy‐decomposition analysis. The theoretical results predict that the heavier Group 14 complexes [(PMe3)2Cl2M(E)] and [(PMe3)2(CO)2M(E)] with E=Si, Ge, Sn have C2v equilibrium geometries in which the PMe3 ligands are in the axial positions. The complexes have strong M? E bonds which are slightly stronger in the 16‐VE species 1ME than in the 18‐VE complexes 2ME . The calculated bond dissociation energies show that the M? E bonds become weaker in both series in the order C>Si>Ge>Sn; the bond strength increases in the order Fe<Ru<Os for 1ME , whereas a U‐shaped trend Ru<Os<Fe is found for 2ME . The M? E bonding analysis suggests that the 16‐VE complexes 1ME have two electron‐sharing bonds with σ and π symmetry and one donor–acceptor π bond like the carbon complex. Thus, the bonding situation is intermediate between a typical Fischer complex and a Schrock complex. In contrast, the 18‐VE complexes 2ME have donor–acceptor bonds, as suggested by the Dewar–Chatt–Duncanson model, with one M←E σ donor bond and two M→E π‐acceptor bonds, which are not degenerate. The shape of the frontier orbitals reveals that the HOMO?2 σ MO and the LUMO and LUMO+1 π* MOs of 1ME are very similar to the frontier orbitals of CO.  相似文献   

17.
The NiII‐mediated tautomerization of the N‐heterocyclic hydrosilylcarbene L2Si(H)(CH2)NHC 1 , where L2=CH(C?CH2)(CMe)(NAr)2, Ar=2,6‐iPr2C6H3; NHC=3,4,5‐trimethylimidazol‐2‐yliden‐6‐yl, leads to the first N‐heterocyclic silylene (NHSi)–carbene (NHC) chelate ligand in the dibromo nickel(II) complex [L1Si:(CH2)(NHC)NiBr2] 2 (L1=CH(MeC?NAr)2). Reduction of 2 with KC8 in the presence of PMe3 as an auxiliary ligand afforded, depending on the reaction time, the N‐heterocyclic silyl–NHC bromo NiII complex [L2Si(CH2)NHCNiBr(PMe3)] 3 and the unique Ni0 complex [η2(Si‐H){L2Si(H)(CH2)NHC}Ni(PMe3)2] 4 featuring an agostic Si? H→Ni bonding interaction. When 1,2‐bis(dimethylphosphino)ethane (DMPE) was employed as an exogenous ligand, the first NHSi–NHC chelate‐ligand‐stabilized Ni0 complex [L1Si:(CH2)NHCNi(dmpe)] 5 could be isolated. Moreover, the dicarbonyl Ni0 complex 6 , [L1Si:(CH2)NHCNi(CO)2], is easily accessible by the reduction of 2 with K(BHEt3) under a CO atmosphere. The complexes were spectroscopically and structurally characterized. Furthermore, complex 2 can serve as an efficient precatalyst for Kumada–Corriu‐type cross‐coupling reactions.  相似文献   

18.
The structure of a pincer ligand consists of a backbone and two `arms' which typically contain a P or N atom. They are tridentate ligands that coordinate to a metal center in a meridional configuration. A series of three iron complexes containing the pyrrole‐based PNP pincer ligand 2,5‐bis[(diisopropylphosphanyl)methyl]pyrrolide (PNpyrP) has been synthesized. These complexes are possible precursors to new iron catalysts. {2,5‐Bis[(diisopropylphosphanyl)methyl]pyrrolido‐κ3P ,N ,P ′}carbonylchlorido(trimethylphosphane‐κP )iron(II), [Fe(C18H34NP2)Cl(C3H9P)(CO)] or [Fe(PNpyrP)Cl(PMe3)(CO)], (I), has a slightly distorted octahedral geometry, with the Cl and CO ligands occupying the apical positions. {2,5‐Bis[(diisopropylphosphanyl)methyl]pyrrolido‐κ3P ,N ,P ′}chlorido(pyridine‐κN )iron(II), [Fe(C18H34NP2)Cl(C5H5N)] or [Fe(PNpyrP)Cl(py)] (py is pyridine), (II), is a five‐coordinate square‐pyramidal complex, with the pyridine ligand in the apical position. {2,5‐Bis[(diisopropylphosphanyl)methyl]pyrrolido‐κ3P ,N ,P ′}dicarbonylchloridoiron(II), [Fe(C18H34NP2)Cl(CO)2] or [Fe(PNpyrP)Cl(CO)2], (III), is structurally similar to (I), but with the PMe3 ligand replaced by a second carbonyl ligand from the reaction of (II) with CO. The two carbonyl ligands are in a cis configuration, and there is positional disorder of the chloride and trans carbonyl ligands.  相似文献   

19.
A highly enantioselective tandem Michael/ring‐closure reaction of α,β‐unsaturated pyrazoleamides and amidomalonates has been accomplished in the presence of a chiral N,N′‐dioxide–Yb(OTf)3 complex (Tf: trifluoromethanesulfonyl) to give various substituted chiral glutarimides with high yields and diastereo‐ and enantioselectivities. Moreover, this methodology could be used for gram‐scale manipulation and was successfully applied to the synthesis of (?)‐paroxetine. Further nonlinear and HRMS studies revealed that the real catalytically active species was a monomeric L ‐PMe2 –Yb3+ complex. A plausible transition state was proposed to explain the origin of the asymmetric induction.  相似文献   

20.
The aromatic C? C bond cleavage by a tungsten complex reported recently by Sattler and Parkin 15 offers fresh opportunities for the functionalization of organic molecules. The mechanism of such a process has not yet been determined, which appeals to computational assistance to understand how the unstrained C? C bond is activated at the molecular level. 16 , 17 In this work, by performing density functional theory calculations, we studied various possible mechanisms of cleavage of the aromatic C? C bond in quinoxaline (QoxH) by the W‐based complex [W(PMe3)42‐CH2PMe2)H]. The calculated results show that the mechanism proposed by Sattler and Parkin involves an overall barrier of as high as 42.0 kcal mol?1 and thus does not seem to be consistent with the experimental observation. Alternatively, an improved mechanism has been presented in detail, which involves the removal and recoordination of a second PMe3 ligand on the tungsten center. In our new mechanism, it is proposed that the C? C cleavage occurs prior to the second C? H bond addition, in contrast to Sattler and Parkin’s mechanism in which the C? C bond is broken after the second C? H bond addition. We find that the rate‐determining step of the reaction is the ring‐opening process of the tungsten complex with an activation barrier of 28.5 kcal mol?1 after the first PMe3 ligand dissociation from the metal center. The mono‐hydrido species is located as the global minimum on the potential‐energy surface, which is in agreement with the experimental observation for this species. The present theoretical results provide new insight into the mechanism of the remarkable C? C bond cleavage.  相似文献   

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