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1.
Damir A. Safin Dr. Piotr Mlynarz F. Ekkehardt Hahn Prof. Dr. Maria G. Babashkina Felix D. Sokolov Nail G. Zabirov Joanna Galezowska Henryk Kozlowski 《无机化学与普通化学杂志》2007,633(9):1472-1479
Structure and magnetic properties of N‐diisopropoxyphosphorylthiobenzamide PhC(S)‐N(H)‐P(O)(OiPr)2 ( HLI ) and N‐diisopropoxyphosphoryl‐N′‐phenylthiocarbamide PhN(H)‐C(S)‐N(H)‐P(O)(OiPr)2 ( HLII ) complexes with the CoII cation of formulas [Co{PhC(S)‐N‐P(O)(OiPr)2}2] ( 1 ), [Co{PhN(H)‐C(S)‐N‐P(O)(OiPr)2}2] ( 2 ), [Co{PhC(S)‐N(H)‐P(O)(OiPr)2}2{PhC(S)‐N‐P(O)(OiPr)2}2] ( 1a ) and [Co{PhC(S)‐N‐P(O)(OiPr)2}2}(2,2′‐bipy)] ( 3 ), [Co{PhC(S)‐N‐P(O)(OiPr)2}2(1,10‐phen)] ( 4 ), [Co{PhN(H)‐C(S)‐N‐P(O)(OiPr)2}2(2,2′‐bipy)] ( 5 ), [Co{PhN(H)‐C(S)‐N‐P(O)(OiPr)2}2(1,10‐phen)] ( 6 ) were investigated. Paramagnetic shifts in the 1H NMR spectrum were observed for high‐spin CoII complexes with HLI,II , incorporating the S‐C‐N‐P‐O chelate moiety and two aromatic chelate ligands. Investigation of the thermal dependence of the magnetic susceptibility has shown that the extended materials 1‐2 and 6 show ferromagnetic exchange between distorted tetrahedral ( 1 , 2 ) or octahedral ( 1a , 6 ) metal atoms whereas 3 and 5 show antiferromagnetic properties. Compound 4 behaves as a spin‐canted ferromagnet, an antiferromagnetic ordering taking place below a critical temperature, Tc = 115 K. Complexes 1 and 1a were investigated by single crystal X‐ray diffraction. The cobalt(II) atom in complex 1 resides a distorted tetrahedral O2S2 environment formed by the C=S sulfur atoms and the P=O oxygen atoms of two deprotonated ligands. Complex 1a has a tetragonal‐bipyramidal structure, Co(Oax)2(Oeq)2(Seq)2, and two neutral ligand molecules are coordinated in the axial positions through the oxygen atoms of the P=O groups. The base of the bipyramid is formed by two anionic ligands in the typical 1,5‐O,S coordination mode. The ligands are in a trans configuration. 相似文献
2.
Ian Sarvary Fredrik Almqvist Torbjörn Frejd 《Chemistry (Weinheim an der Bergstrasse, Germany)》2001,7(10):2158-2166
Reductions performed with TiIV complexes of ligands based on bicyclo[2.2.2]octane diols 5 and 6 are effective catalysts in the reduction of prochiral ketones to optically active alcohols, with catecholborane as the reducing agent. Methyl ketones are favored and enantiomeric excesses (ee) of ≤98 % have been achieved with acetophenone as the substrate. Several other substrates were tested, among them 2-octanone, which gave 2-octanol in 87 % ee. Further details of the method were examined, for example, temperature, solvent composition, amount of molecular sieves (4 Å), and catecholborane quality, as well as the sensitivity of the ligands towards acids. NMR spectroscopic methods were used to gain some insight into the complexes formed between the ligands and [Ti(OiPr)4]. A dimeric structure is proposed for the pre-catalyst. 相似文献
3.
Phosphoramidate‐Supported Cp*IrIII Aminoborane H2B=NR2 Complexes: Synthesis,Structure, and Solution Dynamics
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Marcus W. Drover Eric G. Bowes Prof. Dr. Laurel L. Schafer Prof. Dr. Jennifer A. Love Prof. Dr. Andrew S. Weller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(20):6793-6797
Reaction of aminoboranes H2B=NR2 (R=iPr or Cy) with the cationic Cp*IrIII phosphoramidate complex [IrCp*{κ2‐N,O‐Xyl(N)P(O)(OEt)2}][BArF4] generates the aminoborane complexes [IrCp*(H){κ1‐N‐η2‐HB‐Xyl(N)P(OBHNR2)(OEt)2}][BArF4] (R=iPr or Cy) in which coordination of a P=O bond with boron weakens the B=N multiple bond. For these complexes, solution‐ and solid‐state, as well as DFT computational techniques, have been employed to substantiate B?N bond rotation of the coordinated aminoborane. 相似文献
4.
Lidiya I. Kursheva Olga N. Kataeva Dmitry B. Krivolapov Aidar T. Gubaidullin Elvira S. Batyeva Oleg G. Sinyashin 《Heteroatom Chemistry》2008,19(5):483-489
Some Cu(I) halides complexes based on P(III) acid esters,{[(RE)3PCuBr] (where E = O, N, S); R = n‐Pr, i‐Pr, Et2N} were obtained and characterized using IR, 31P NMR spectroscopy, and single crystal X‐ray diffraction. The comparative structural characteristics of complexes with various donor atoms (E = O, N, S) are analyzed. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:483–489, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20459 相似文献
5.
Dr. Sida Wang Dr. Phil Liebing Dr. Martin Feneberg Prof. Farid M. Sroor Dr. Felix Engelhardt Dr. Liane Hilfert Dr. Sabine Busse Elias Kluth Prof. Dr. Rüdiger Goldhahn Prof. Dr. Frank T. Edelmann 《欧洲无机化学杂志》2023,26(14):e202300027
A series of new alkynylamidinate complexes of selected first and second row transition metals has been synthesized and fully characterized. Treatment of MCl2 precursors (M=Mn, Fe, Co) with 2 equiv. of the lithium alkynylamidinates Li[c-C3H5−C≡C−C(NR′)2] ⋅ THF (R′=iPr (2), Cy (cyclohexyl) ( 2 )) afforded a series of binuclear complexes of the type M2[c-C3H5−C≡C−C(NR)2-κN:κN′]2[c-C3H5−C≡C−C(NR)2-κ2N,N′]2 ( 3 : M=Mn, R=Cy; 4 a : M=Fe, R=iPr; 4 b : M=Fe, R=Cy; 5 : M=Co, R=iPr) with no significant metal-metal bonding. In marked contrast, a similar reaction of CrCl2 with 2 equiv. of 1 afforded the homoleptic dinuclear chromium(II) complex Cr2[c-C3H5−C≡C−C(NiPr)2-κN:κN′]4 ( 6 ) which supposedly comprises a Cr−Cr quadruple bond. Complex 6 could also be prepared in a more rational way and in better yield (61 %) by using dichromium(II) tetraacetate, Cr2(OAc)4, as starting material. Related reactions employing dimolybdenum(II) tetraacetate, Mo2(OAc)4, and 2 or 3 equiv. of 1 afforded the mixed-ligand paddle wheel-type complexes trans-Mo2(OAc-κO:κO′)2([c-C3H5−C≡C−C(NiPr)2-κN:κN′]2 ( 7 ) and Mo2(OAc-κO:κO′)([c-C3H5−C≡C−C(NiPr)2-κN:κN′]3 ( 8 ). All title compounds were structurally characterized through single-crystal X-ray diffraction and spectroscopic techniques (NMR, IR, Raman). 相似文献
6.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(45):14470-14474
Facile oxygenation of the acyclic amido‐chlorosilylene bis(N‐heterocyclic carbene) Ni0 complex [{N(Dipp)(SiMe3)ClSi:→Ni(NHC)2] ( 1 ; Dipp=2,6‐iPr2C6H4; N‐heterocyclic carbene=C[(iPr)NC(Me)]2) with N2O furnishes the first Si‐metalated iminosilane, [DippN=Si(OSiMe3)Ni(Cl)(NHC)2] ( 3 ), in a rearrangement cascade. Markedly, the formation of 3 proceeds via the silanone (Si=O)–Ni π‐complex 2 as the initial product, which was predicted by DFT calculations and observed spectroscopically. The Si=O and Si=N moieties in 2 and 3 , respectively, show remarkable hydroboration reactivity towards H−B bonds of boranes, in the former case corroborating the proposed formation of a (Si=O)–Ni π‐complex at low temperature. 相似文献
7.
A thorough study on copper-free Sonogashira cross-couplings in water was carried out using the palladacycle, [{Pd(μ-Cl){κ2-P,C-P(iPr)2(OC6H3-2-Ph)}}2] as pre-catalyst with different bases and palladium concentrations. The highly active pre-catalyst imparts good to near quantitative yields using a concentration of 0.25 mol % at 40 °C. This broadly applicable protocol exhibits high tolerance of functional groups and substitution patterns. 相似文献
8.
Charge Effects in PCP Pincer Complexes of NiII bearing Phosphinite and Imidazol(i)ophosphine Coordinating Jaws: From Synthesis to Catalysis through Bonding Analysis
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Dr. Boris Vabre Dr. Yves Canac Dr. Christine Lepetit Dr. Carine Duhayon Prof. Remi Chauvin Prof. Davit Zargarian 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(48):17403-17414
This contribution reports on a new family of NiII pincer complexes featuring phosphinite and functional imidazolyl arms. The proligands RPIMCHOPR′ react at room temperature with NiII precursors to give the corresponding complexes [(RPIMCOPR′)NiBr], where RPIMCOPR=κP,κC,κP‐{2‐(R′2PO),6‐(R2PC3H2N2)C6H3}, R=iPr, R′=iPr ( 3 b , 84 %) or Ph ( 3 c , 45 %). Selective N‐methylation of the imidazole imine moiety in 3 b by MeOTf (OTf=OSO2CF3) gave the corresponding imidazoliophosphine [(iPrPIMIOCOPiPr)NiBr][OTf], 4 b , in 89 % yield (iPrPIMIOCOPiPr=κP,κC,κP‐{2‐(iPr2PO),6‐(iPr2PC4H5N2)C6H3}). Treating 4 b with NaOEt led to the NHC derivative [(NHCCOPiPr)NiBr], 5 b , in 47 % yield (NHCCOPiPr=κP,κC,κC‐{2‐(iPr2PO),6‐(C4H5N2)C6H3)}). The bromo derivatives 3–5 were then treated with AgOTf in acetonitrile to give the corresponding cationic species [(RPIMCOPR)Ni(MeCN)][OTf] [R=Ph, 6 a (89 %) or iPr, 6 b (90 %)], [(RPIMIOCOPR)Ni(MeCN)][OTf]2 [R=Ph, 7 a (79 %) or iPr, 7 b (88 %)], and [(NHCCOPR)Ni(MeCN)][OTf] [R=Ph, 8 a (85 %) or iPr, 8 b (84 %)]. All new complexes have been characterized by NMR and IR spectroscopy, whereas 3 b , 3 c , 5 b , 6 b , and 8 a were also subjected to X‐ray diffraction studies. The acetonitrile adducts 6 – 8 were further studied by using various theoretical analysis tools. In the presence of excess nitrile and amine, the cationic acetonitrile adducts 6 – 8 catalyze hydroamination of nitriles to give unsymmetrical amidines with catalytic turnover numbers of up to 95. 相似文献
9.
Jun Wang Dr. Wentao Wang Wei Li Xiaolei Hu Ke Shen Cheng Tan Dr. Xiaohua Liu Dr. Xiaoming Feng Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(43):11642-11659
Full investigation of cyanation of aldehydes, ketones, aldimines and ketimines with trimethylsilyl cyanide (TMSCN) or ethyl cyanoformate (CNCOOEt) as the cyanide source has been accomplished by employing an in situ generated catalyst from cinchona alkaloid, tetraisopropyl titanate [Ti(OiPr)4] and an achiral modified biphenol. With TMSCN as the cyanide source, good to excellent results have been achieved for the Strecker reaction of N‐Ts (Ts=p‐toluenesulfonyl) aldimines and ketimines (up to >99 % yield and >99 % ee) as well as for the cyanation of ketones (up to 99 % yield and 98 % ee). By using CNCOOEt as the alternative cyanide source, cyanation of aldehyde was accomplished and various enantioenriched cyanohydrin carbonates were prepared in up to 99 % yield and 96 % ee. Noteworthy, CNCOOEt was successfully employed for the first time in the asymmetric Strecker reaction of aldimines and ketimines, affording various α‐amino nitriles with excellent yields and ee values (up to >99 % yield and >99 % ee). The merits of current protocol involved facile availability of ligand components, operational simplicity and mild reaction conditions, which made it convenient to prepare synthetically important chiral cyanohydrins and α‐amino nitriles. Furthermore, control experiments and NMR analyses were performed to shed light on the catalyst structure. It is indicated that all the hydroxyl groups in cinchona alkaloid and biphenol complex with TiIV, forming the catalyst with the structure of (biphenoxide)Ti(OR*)(OiPr). The absolute configuration adopted by biphenol 4 m in the catalyst was identified as S configuration according to the evidence from control experiments and NMR analyses. Moreover, the roles of the protonic additive (iPrOH) and the tertiary amine in the cinchona alkaloid were studied in detail, and the real cyanide reagent in the catalytic cycle was found to be hydrogen cyanide (HCN). Finally, two plausible catalytic cycles were proposed to elucidate the reaction mechanisms. 相似文献
10.
Dr. Ranjeesh Thenarukandiyil Dr. Vanaparthi Satheesh Dr. Linda J. W. Shimon Dr. Graham de Ruiter 《化学:亚洲杂志》2021,16(8):999-1006
During the past decade earth-abundant metals have become increasingly important in homogeneous catalysis. One of the reactions in which earth-abundant metals have found important applications is the hydroboration of unsaturated C−C and C−X bonds (X=O or N). Within these set of transformations, the hydroboration of challenging substrates such as nitriles, carbonates and esters still remain difficult and often relies on elaborate ligand designs and highly reactive catalysts (e. g., metal alkyls/hydrides). Here we report an effective methodology for the hydroboration of challenging C≡N and C=O bonds that is simple and applicable to a wide set of substrates. The methodology is based on using a manganese(II) triflate salt that, in combination with commercially available potassium tert-butoxide and pinacolborane, catalyzes the hydroboration of nitriles, carbonates, and esters at room temperature and with near quantitative yields in less than three hours. Additional studies demonstrated that other earth-abundant metal triflate salts can facilitate this reaction as well, which is further discussed in this report. 相似文献
11.
Christine Artner Matthias Czakler Prof. Dr. Ulrich Schubert 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(2):493-498
Mixed‐metal clusters have been obtained from the reaction of titanium alkoxides with either strontium or lead acetate and methacrylic acid. The structures of the clusters are derived from the metallacycle Ti8O8(methacrylate)16. The Sr and Pb atoms in Sr2Ti8O8X2(OOCMe)2(methacrylate)16 (X: acetate or OiPr) and Pb2Ti8O8(OBu)2X2(methacrylate)16(BuOH)2 (X: acetate or methacrylate) occupy the central cavity of the Ti8O8 ring. In addition to the crown‐ether‐like coordination of the ring oxygen atoms to the Sr or Pb atoms, bridging carboxylate ligands support the coordination of the latter atoms. In the compound Pb2Ti6O5(OiPr)3X(methacrylate)14 (X: OiPr or methacrylate), the lead atoms are coordinated by a fragment of the Ti8O8(methacrylate)16 metallacycle. 相似文献
12.
《无机化学与普通化学杂志》2018,644(15):844-848
Titanium and zirconium complexes supported by a pyrrolide ligand HL1 [HL1 = 2‐cyano‐1H‐pyrrole], Ti2(L2)2(NMe2)2 ( 1 ) and Zr3(L2)3(NMe2)6 ( 2 ) [L2 = N,N‐dimethyl‐1H‐pyrrol‐2‐carboximidamide, NMe2‐L1] were synthesized and characterized. The ligand L2 was generated by activation of C≡N bond of HL1 with HNMe2. In complex 1 , two TiIV atoms are bridged by two nitrogen atoms. There are three characteristic ZrIV ions in 2 , which are six‐, seven‐ and six‐coordinate, respectively. They were tested as catalysts for the intramolecular hydroamination of aminoalkenes, and the respective N‐heterocycles were afforded in 74–99 % yields. Moreover, the formation of L2 ligand indicates that the amination of C≡N bond can be considered as a new and rapid way to synthesize other C–N bonds. 相似文献
13.
Dr. Pei Jen Tiong Laura R. Groom Dr. Eric Clot Prof. Dr. Philip Mountford 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(13):4198-4216
We report a detailed study of the reactions of the Ti?NNCPh2 alkylidene hydrazide functional group in [Cp*Ti{MeC(NiPr)2}(NNCPh2)] ( 8 ) with a variety of unsaturated and saturated substrates. Compound 8 was prepared from [Cp*Ti{MeC(NiPr)2}(NtBu)] and Ph2CNNH2. DFT calculations were used to determine the nature of the bonding for the Ti?NNCPh2 moiety in 8 and in the previously reported [Cp2Ti(NNCPh2)(PMe3)]. Reaction of 8 with CO2 gave dimeric [(Cp*Ti{MeC(NiPr)2}{μ‐OC(NNCPh2)O})2] and the “double‐insertion” dicarboxylate species [Cp*Ti‐{MeC(NiPr)2}{OC(O)N(NCPh2)C(O)O}] through an initial [2+2] cycloaddition product [Cp*Ti{MeC(NiPr)2}{N(NCPh2)C(O)O}], the congener of which could be isolated in the corresponding reaction with CS2. The reaction with isocyanates or isothiocyanates tBuNCO or ArNCE (Ar=Tol or 2,6‐C6H3iPr2; E=O, S) gave either complete NNCPh2 transfer, [2+2] cycloaddition to Ti?Nα or single‐ or double‐substrate insertion into the Ti?Nα bond. The treatment of 8 with isonitriles RNC (R=tBu or Xyl) formed σ‐adducts [Cp*Ti{MeC(NiPr)2}(NNCPh2)(CNR)]. With ArF5CCH (ArF5=C6F5) the [2+2] cycloaddition product [Cp*Ti{MeC(NiPr)2}{N(NCPh2)C(ArF5)C(H)}] was formed, whereas with benzonitriles ArCN (Ar=Ph or ArF5) two equivalents of substrate were coupled in a head‐to‐tail manner across the Ti?Nα bond to form [Cp*Ti{MeC(NiPr)2}{N(NCPh2)C(Ar)NC(Ar)N}]. Treatment of 8 with RSiH3 (R=aryl or Bu) or Ph2SiH2 gave [Cp*Ti{MeC(NiPr)2}{N(SiHRR′)N(CHPh2)}] (R′=H or Ph) through net 1,3‐addition of Si? H to the N? N?CPh2 linkage of 8 , whereas reaction with PhSiH2X (X=Cl, Br) led to the Ti?Nα 1,2‐addition products [Cp*Ti{MeC(NiPr)2}(X){N(NCPh2)SiH2Ph}]. 相似文献
14.
Reaction of (rac)‐3,3′‐bis(methoxymethyl)‐BINOL [H2(CH3OCH2)2BINO] with excess Ti(OiPr)4 and one equivalent of H2O in CH2Cl2 affords a trinuclear titanium(IV) complex [{(CH3OCH2)2BINO}Ti3(μ3‐O)(OiPr)6(μ2‐OiPr)2]. By dissolving it in dichloromethane and hexane and cooling to 0 °C, plate‐like pale yellow single crystals (monoclinic, P21/n, a = 12.605(3), b = 21.994(5), c = 19.090(4) Å, β = 92.764(8)°, V = 5286.2(19) Å3, T = 293(2) K) were obtained. Each oxygen atom at 2 or 2′ position of the (CH3OCH2)2BINO ligand bonds to only one titanium atom. There is no interaction between the third Ti atom and the two oxygen atoms of 3,3′‐bis(methoxymethyl)‐BINOLate. 相似文献
15.
Kai Li Hongjian Sun Wenjing Yang Yajie Wang Shangqing Xie Xiaoyan Li Olaf Fuhr Dieter Fenske 《应用有机金属化学》2020,34(3):e5337
A series of phosphorus-chalcogen chelated hydrido iron (II) complexes 1–7 , (o-(R'2P)-p-R-C6H4Y)FeH (PMe3)3 ( 1 : R = H, R' = Ph, Y = O; 2 : R = Me, R' = Ph, Y = O; 3 : R = H, R' = iPr, Y = O; 4 : R = Me, R' = iPr, Y = O; 5 : R = H, R' = Ph, Y = S; 6 : R = Me, R' = Ph, Y = S; 7 : R = H, R' = Ph, Y = Se), were synthesized. The catalytic performances of 1–7 for dehydration of amides to nitriles were explored by comparing three factors: (1) different chalcogen coordination atoms Y; (2) R' group of the phosphine moiety; (3) R substituent group at the phenyl ring. It is confirmed that 5 with S as coordination atom has the best catalytic activity and 7 with Se as coordination atom has the poorest catalytic activity among complexes 1 , 5 and 7 . Electron-rich complex 4 is the best catalyst among the seven complexes and the dehydration reaction was completed by using 2 mol% catalyst loading at 60 °C with 24 hr in the presence of (EtO)3SiH in THF. Catalyst 4 has good tolerance to many functional groups. Among the seven iron complexes, new complexes 3 and 4 were obtained via the O-H bond activation of the preligands o-iPr2P(C6H4)OH and o-iPr2P-p-Me-(C6H4)OH by Fe(PMe3)4. Both 3 and 4 were characterized by spectroscopic methods and X-ray diffraction analysis. The catalytic mechanism was experimentally studied and also proposed. 相似文献
16.
S. R. Garaeva A. A. Medzhidov O. Beukgunger A. Aydin B. Yalcin M. G. Abbasov 《Russian Journal of Coordination Chemistry》2012,38(2):140-144
The heterovalent trinuclear cobalt complexes [Co2IIIL4
i
· CoII(H2O)4] · nXmY (L
i
are deprotonated Schiff bases derived from substituted salicylaldehydes and β-alanine; i = 1–3) were obtained and characterized. An X-ray diffraction study of the trinuclear cobalt complex with N-(2-carboxyethyl)salicylaldimine
showed that the central Co(II) ion and the terminal Co(III) ions are linked by bridging carboxylate groups. Either terminal
Co(III) atom is coordinated to two ligand molecules. They form an octahedral environment consisting of two azomethine N atoms,
two phenolate O atoms, and two O atoms of two carboxylate groups. The central Co(II) atom is coordinated to four water molecules
and to two O atoms of two bridging carboxylate ligands involved in the coordination sphere of the terminal Co(III) atoms. 相似文献
17.
L. G. Detsuheva M. A. Fedotov L. I. Kuznetsova A. A. Vlasov V. A. Likholobov 《Russian Chemical Bulletin》1997,46(5):874-880
Unsaturated heteropolyanions (HPA) [PW11O39]7− stabilize TiIV hydroxo complexes in aqueous solutions (Ti: PW11 [PW11O39]7−⪯12, pH 1–3). Spectral studies (optical,17O and31P NMR, and IR spectra) and studies by the differential dissolution method demonstrated that TiIV hydroxo complexes are stabilized through interactions of polynuclear TiIV hydroxo cations with heteropolyanions [PW11TiO40
5− formed. Depending on the reaction conditions, hydroxo cations Ti
n−1O
x
H
y
m+ either add to oxygen atoms of the W−O−Ti bridges of the heteropolyanions to form the complex [PW11TiO40·Ti
n−1O
x
H
y
]
k−
(at [HPA]=0.01 mol L−1) or interact with TiIV of the heteropolyanions through the terminal o atom to give the polynuclear complexes [PW11O39Ti−O−Ti
n−1O
x
H
y
]q− (at [HPA]=0.2 mol L−1). When the complexes of the first type were treated with H2O2, TiIV ions added peroxo groups.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 914–920, May, 1997. 相似文献
18.
Tim Kemmitt Graeme J. Gainsford Hana Robson‐Marsden 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(5):m310-m312
The title compound, bis(2,2′‐methyliminodiethanolato)‐1κ3O,N,O′;3κ3O,N,O′‐di‐μ3‐propane‐1,3‐diolato‐1:2:3κ8O:O,O′:O′‐μ‐propane‐1,3‐diolato‐1:3κ2O:O′‐propane‐1,3‐diolato‐2κ2O,O′‐trititanium(IV), [Ti3(C5H11NO2)2(C3H6O2)4], has four 1,3‐propanediolate ligands binding in three different modes. Two ligands chelate adjacent Ti atoms with normal μ3‐O bridges, giving typical edge‐sharing of the Ti distorted octahedra, one chelating to the central Ti atom with no μ‐bridging, and the other spanning the cluster, binding only to the outermost Ti atoms. The two methyliminodiethanolate ligands each coordinate to the outer Ti atoms via their N and two O atoms. The Ti—O bond lengths range, in a self‐consistent fashion, from 1.816 (2) to 2.082 (2) Å, while the average Ti—N distance is 2.391 (3) Å. 相似文献
19.
Dr. Robert Langer Dr. Mark A. Iron Dr. Leonid Konstantinovski Dr. Yael Diskin‐Posner Dr. Gregory Leitus Yehoshoa Ben‐David Prof. Dr. David Milstein 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(23):7196-7209
The new, structurally characterized hydrido carbonyl tetrahydridoborate iron pincer complex [(iPr‐PNP)Fe(H)(CO)(η1‐BH4)] ( 1 ) catalyzes the base‐free hydrogenation of ketones to their corresponding alcohols employing only 4.1 atm hydrogen pressure. Turnover numbers up to 1980 at complete conversion of ketone were reached with this system. Treatment of 1 with aniline (as a BH3 scavenger) resulted in a mixture of trans‐[(iPr‐PNP)Fe(H)2(CO)] ( 4 a ) and cis‐[(iPr‐PNP)Fe(H)2(CO)] ( 4 b ). The dihydrido complexes 4 a and 4 b do not react with acetophenone or benzaldehyde, indicating that these complexes are not intermediates in the catalytic reduction of ketones. NMR studies indicate that the tetrahydridoborate ligand in 1 dissociates prior to ketone reduction. DFT calculations show that the mechanism of the iron‐catalyzed hydrogenation of ketones involves alcohol‐assisted aromatization of the dearomatized complex [(iPr‐PNP*)Fe(H)(CO)] ( 7 ) to initially give the Fe0 complex [(iPr‐PNP)Fe(CO)] ( 21 ) and subsequently [(iPr‐PNP)Fe(CO)(EtOH)] ( 38 ). Concerted coordination of acetophenone and dual hydrogen‐atom transfer from the PNP arm and the coordinated ethanol to, respectively, the carbonyl carbon and oxygen atoms, leads to the dearomatized complex [(iPr‐PNP*)Fe(CO)(EtO)(MeCH(OH)Ph)] ( 32 ). The catalyst is regenerated by release of 1‐phenylethanol, followed by dihydrogen coordination and proton transfer to the coordinated ethoxide ligand. 相似文献
20.
The Mechanism of CO2 Insertion into Iridium(I) Hydroxide and Alkoxide Bonds: A Kinetics and Computational Study
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Dr. Byron J. Truscott Hedi Kruger Dr. Paul B. Webb Prof. Dr. Michael Bühl Prof. Dr. Steven P. Nolan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(18):6930-6935
The facile insertion of CO2 into iridium(I) hydroxide, alkoxide, and amide bonds was recently reported. In particular, [Ir(cod)(IiPr)(OH)] (IiPr=1,3‐bis(isopropyl)imidazol‐2‐ylidene) reacted with CO2 in solution and in the solid state in a matter of minutes to give the novel [{Ir(cod)(IiPr)}2(μ‐κ1O:κ2O,O‐CO3)] complex. In the present study, this reaction is probed using kinetics and theoretical studies, which enabled us to analyse its facile nature and to fully elucidate the reaction mechanism with excellent correlation between the two methods. 相似文献