共查询到20条相似文献,搜索用时 15 毫秒
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Poverenov E Gandelman M Shimon LJ Rozenberg H Ben-David Y Milstein D 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(19):4673-4684
Novel anionic dialkyl, diaryl, and dihydride platinum(II) complexes based on the new "long-arm" hemilabile PCN-type ligand C6H4[CH2P(tBu)2](CH2)2N(CH3)2 with the general formula Li+[Pt(PCN)(R)2]- (R=Me (4), Ph (6) and H (9)) were prepared by reaction of [Pt(PCN)(R)] complexes (obtained from the corresponding chlorides) with an equivalent of RLi, as a result of the opening of the chelate ring. Alkylating agents based on other metals produce less stable products. These anionic d8 complexes are thermally stable although they bear no stabilizing pi acceptors. They were characterized by 1H, 31P[1H], 13C, and 7Li NMR spectroscopy; complex 9 was also characterized by single crystal X-ray crystallography, showing that the Li+ ion is coordinated to the nitrogen atom of the open amine arm and to the hydride ligand (trans to the P atom) of a neighboring molecule (H--Li=2.15 A), resulting in a dimeric structure. Complexes 4 and 9 exhibit high nucleophilic reactivity, upon which the pincer complex is regenerated. Reaction of 4 with water, methyl iodide, and iodobenzene resulted in the neutral complex [Pt(PCN)(CH3)] (3) and methane, ethane, or toluene, respectively. Labeling studies indicate that the reaction proceeds by direct electrophilic attack on the metal center, rather than attack on the alkyl ligand. The anionic dihydride complex 9 reacted with water and methyl iodide to yield [Pt(PCN)(H)] (8) and H2 or methane, respectively. 相似文献
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M.Ju. Afonin V.A. Maksakov V.P. Kirin L.A. Scheludyakova A.V. Golovin V.G. Vasilev 《Polyhedron》2009,28(13):2754-2758
The cluster complexes (μ-H)Os3(μ-OCR)(СО)10 (R = Me (1); R = Ph (2)) catalyze the allylic rearrangement of N-allylacetamide at room temperature. Microwave irradiation greatly (by more than several thousand-fold) accelerates the reaction between the solution of 2 and allylacetamide. The interaction of cluster 2 with allylamine both at room and elevated temperatures results in cleavage of the C–N bond and coordination of the allylic fragment to one of the osmium atoms with the formation of Os3(CO)9(μ,η2-OC-Ph)(η3-C3H5) (4) cluster. 相似文献
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Snelders DJ van Koten G Klein Gebbink RJ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(1):42-57
The effects of introducing ionic functionalities in phosphine ligands on the coordination chemistry of these ligands and the catalytic behavior of the corresponding metal complexes are reviewed. The steric and electronic consequences of such functionalizations are discussed. Apart from these steric and electronic effects, the presence of charged groups often leads to additional, supramolecular interactions that occur in the second coordination sphere of the metal complex, such as intramolecular, interligand hydrogen bonding and Coulombic repulsion. These interactions can significantly alter the behavior of the phosphine ligand in question. Such effects have been observed in phosphine-metal association/dissociation equilibria, ligand substitution reactions, and stereoisomerism in phosphine-metal complexes. By drawing general conclusions, this review offers an insight into the coordination and catalytic behavior of phosphine ligands containing ionic functionalities and their corresponding metal complexes. 相似文献
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Jaska CA Dorn H Lough AJ Manners I 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(1):271-281
Reaction of [Pt(PEt(3))(3)] with the primary and secondary phosphine-borane adducts PhRPH x BH(3) (R=H, Ph) resulted in oxidative addition of a P-H bond at the Pt(0) center to afford the complexes trans-[PtH(PPhR x BH(3))(PEt(3))(2)] (1: R=H; 2: R=Ph). The products 1 and 2 were characterized by (1)H, (11)B, (13)C, (31)P, and (195)Pt NMR spectroscopy, and the molecular structures were verified by X-ray crystallography. In both cases, a trans arrangement of the hydride ligand with respect to the phosphidoborane ligand was observed. When 2 was treated with PhPH(2) x BH(3), a novel phosphidoborane ligand-exchange reaction occurred which yielded 1 and Ph(2)PH x BH(3). Treatment of 2 with one equivalent of depe (depe=1,2-bis(diethylphosphino)ethane) resulted in the formation of the complex cis-[PtH(PPh(2) x BH(3))(depe)] (3), in which the hydride ligand and the phosphidoborane ligand are in a cis arrangement. Treatment of 3 with PhPH(2) x BH(3) was found to result in an exchange of the phosphidoborane ligands to give the complex cis-[PtH(PPhH x BH(3))(depe)] (4) and Ph(2)PH x BH(3). Complex 4 was found to undergo further reaction in the presence of PhPH(2) x BH(3) to give meso-cis-[Pt(PPhH x BH(3))(2)(depe)] (5) and rac-cis-[Pt(PPhH x BH(3))(2)(depe)] (6). 相似文献
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S. P. Tunik 《Russian Chemical Bulletin》2004,53(12):2657-2669
The methods of synthesis, structural features, and the reactivity of substituted carbonyl clusters of transition metals containing labile and hemilabile ligands are considered.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2547–2559, December, 2004. 相似文献
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Recent investigations from our laboratory have described compelling experimental evidences that the use of a central 4‐methyl‐3,5‐diacylaminophenyl platform functionalized with two lateral aromatic rings each bearing three appended aliphatic chains is well‐suited to produce liquid crystalline materials, some of which carrying at the tips (A‐substitution position) chelating fragments such as phenanthroline, terpyridine, alkynyl functions, crown ethers or highly luminescent subunits such as difluoroboradiazaindacene or cationic platinum‐terpyridine complexes. An important carvet of this research program is that the presence of amide functions likely stabilizes the mesophases by hydrogen bondings. Judicious grafting of polycatenar tails to the platform insures formation of mesomorphic materials over a large temperature range. Careful design of the system by the direct connection of the platform via alkyne bonds to square planar platinum centers give rise to intriguing phosphorescent metallomesogens. © 2009 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 9: 1–23; 2009: Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.20164 相似文献
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Sumby CJ Gordon KC Walsh TJ Hardie MJ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(14):4415-4425
Investigations of a previously reported ligand, hexakis(2-pyridylmethyl)cyclotricatechylene (1), and a new tetrameric bridging ligand, octakis(2-pyridylmethyl)cyclotetracatechylene (2), the latter constructed on a larger cyclotetraveratrylene (CTTV) scaffold, are described. Variable-temperature NMR studies support a "sofa" conformation for 2, akin to studies on the parent compound. The coordination chemistry of 2 and its smaller trimeric homologue have also been investigated with silver(I), copper(II) and palladium(II) salts. An unexpected chelating mode was observed for 1 in the structure of DMF subset[Pd(3)Cl(6)(1)] x DMF, whereby the palladium cations bridge two veratrole subunits rather than chelating within a single subunit. In the structure of [Ag(4)(2)][Co(C(2)B(9)H(11))(2)](4) x 2.8 CH(3)CN x H(2)O, ligand 2 adopts a "boat" conformation, whereas in [Pd(4)Cl(8)(2)] x 4 H(2)O, (1)H NMR spectroscopic studies and calculations indicate that the ligand is present in a previously unobserved "distorted-cup" conformation. This conformation was calculated to be approximately 90 kJ mol(-1) lower in energy than the alternative "sofa" conformation. Thus, coordination-induced conformational control over CTTV derivatives offers new routes to exploit the host-guest chemistry of these compounds. 相似文献
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Dr. Barbara Müller Dr. Wei‐Zheng Shen Dr. Pablo J. Sanz Miguel Dr. Francisca M. Albertí Dr. Tushar van der Wijst Dr. Marc Noguera Dr. Luis Rodríguez‐Santiago Prof. Mariona Sodupe Prof. Bernhard Lippert 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(36):9970-9983
The preparation and X‐ray crystal structure analysis of {trans‐[Pt(MeNH2)2(9‐MeG‐N1)2]} ? {3 K2[Pt(CN)4]} ? 6 H2O ( 3 a ) (with 9‐MeG being the anion of 9‐methylguanine, 9‐MeGH) are reported. The title compound was obtained by treating [Pt(dien)(9‐MeGH‐N7)]2+ ( 1 ; dien=diethylenetriamine) with trans‐[Pt(MeNH2)2(H2O)2]2+ at pH 9.6, 60 °C, and subsequent removal of the [(dien)PtII] entities by treatment with an excess amount of KCN, which converts the latter to [Pt(CN)4]2?. Cocrystallization of K2[Pt(CN)4] with trans‐[Pt(MeNH2)2(9‐MeG‐N1)2] is a consequence of the increase in basicity of the guanine ligand following its deprotonation and Pt coordination at N1. This increase in basicity is reflected in the pKa values of trans‐[Pt(MeNH2)2(9‐MeGH‐N1)2]2+ (4.4±0.1 and 3.3±0.4). The crystal structure of 3 a reveals rare (N7,O6 chelate) and unconventional (N2,C2,N3) binding patterns of K+ to the guaninato ligands. DFT calculations confirm that K+ binding to the sugar edge of guanine for a N1‐platinated guanine anion is a realistic option, thus ruling against a simple packing effect in the solid‐state structure of 3 a . The linkage isomer of 3 a , trans‐[Pt(MeNH2)2(9‐MeG‐N7)2] ( 6 a ) has likewise been isolated, and its acid–base properties determined. Compound 6 a is more basic than 3 a by more than 4 log units. Binding of metal entities to the N7 positions of 9‐MeG in 3 a has been studied in detail for [(NH3)3PtII], trans‐[(NH3)2PtII], and [(en)PdII] (en=ethylenediamine) by using 1H NMR spectroscopy. Without exception, binding of the second metal takes place at N7, but formation of a molecular guanine square with trans‐[(Me2NH2)PtII] cross‐linking N1 positions and trans‐[(NH3)2PtII] cross‐linking N7 positions could not be confirmed unambiguously, despite the fact that calculations are fully consistent with its existence. 相似文献
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Welsch S Lescop C Balazs G Réau R Scheer M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(33):9130-9141
The reaction of the [{CpMo(CO)(2)}(2)(μ,η(2):η(2)-P(2))] (Cp=cyclopentadienyl) metallo-ligand 2 with pre-organized Cu(I) bi- and trimetallic precursors afforded new coordination complexes with unprecedented coordination modes for a Mo(2)P(2) complex. Variable-temperature solution and solid-state (31)P NMR spectroscopy measurements were performed and X-ray diffraction studies revealed an η(2):η(1) coordination mode for the Mo(2)P(2) unit of 2 in the Cu(I) bimetallic complexes 3 and 4. DFT calculations were carried out to highlight the bonding situation of this unprecedented coordination mode in the Cu(I) bimetallic compound 3. It is built up from a side-on coordination of the P-P σ bond to one copper ion and from the interaction of the lone pair of one phosphorus atom with the second copper ion. The remaining available lone pair of the second phosphorus atom can be involved as well to interact with an additional metal centre, as evidenced in the Cu(I) trimetallic compound 5 in which an η(2):η(1):η(1) coordination mode of the ligand 2 is observed. Derivative 3 can be used as a molecular clip to obtain discrete π-stacked dimers through a ligand exchange reaction between acetonitrile ligands and cyano-capped π-conjugated systems, indicating the stability of the new η(2):η(1) coordination mode. 相似文献
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Chas M Abella D Blanco V Pía E Blanco G Fernández A Platas-Iglesias C Peinador C Quintela JM 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(30):8572-8582
New palladium and platinum metallocycles have been synthesized by reacting 4,4'-bipyridinium-based ligands with PdII and PtII complexes. Strict thermodynamic self-assembly of 1 and [M(en)(NO3)2] (M=Pd, Pt) 6 a,b afforded metallocycles 7 a,b. However, the synthesis of 8 a,b and 9 a,b required a self-assembly process that used sodium p-phenylenediacetate (12) as a template. Finally, metallocycles 10 a,b were synthesized under high dilution conditions from ligand 4. The formation of inclusion complexes between metallocycles 7-10 and substrates 13 and 14 were studied by low-temperature 1H NMR, and the association constants were determined in nitromethane and water by following the characteristic charge-transfer band that these metallomacrocycles show in their UV-visible absorption spectra. A clear correlation between the affinity for a substrate and the dimensions of the metallocycle was observed. Metallocycles 8 b and 9 b exhibited the highest binding constants in water and nitromethane. This observation is in agreement with the DFT (B3LYP)-optimized geometries obtained for the different metallomacrocycles, which indicate that only macrocycles 8 and 9 possess a cavity with a width larger than 3.5 A. The insertion of hydroquinone or diol 13 into the cavity of metallocycle 11 a was confirmed by single-crystal X-ray crystallography. 相似文献
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Amide-based ligands for anion coordination 总被引:1,自引:0,他引:1
Kang SO Begum RA Bowman-James K 《Angewandte Chemie (International ed. in English)》2006,45(47):7882-7894
Anion recognition is an active area of research in supramolecular chemistry. The rapidly increasing amount of structural data now allows anion coordination chemistry to be formalized in terms of coordination numbers and geometries based on hydrogen-bonding interactions between the host (ligand) and the guest (anion). This Minireview targets just one class of anion receptors, namely, amide-based ligands. The structural data for a series of five anion shapes are compiled according to coordination number, and distinct commonalities are observed within a given anion topology. The results also indicate a number of similarities between the coordination of anions and transition-metal ions. 相似文献
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Guest-dependent flexible coordination networks are formed from 1,4-bis(4-pyridylmethyl)tetrafluorobenzene (bpf), 4,4'-bis(4-pyridylmethyl)octafluorobiphenyl (bpfb), 2,6-bis(4-pyridylmethyl)hexafluoronaphthalene (2,6-bpfn), and 2,7-bis(4-pyridylmethyl)hexafluoronaphthalene (2,7-bpfn) with Cd(NO3)2 in the presence of various organic compounds. The reaction of bpf affords one-dimensional cyclic chains, two-dimensional rhombus grid sheets, and three-dimensional diamond frameworks with threefold interpenetration. The reaction of bpfb mainly affords two-dimensional rhombus grid sheets with twofold parallel interpenetration. The reaction of 2,6-bpfn affords a one-dimensional ladder and two-dimensional rhombus grid, twisted grid, and herringbone sheets. The reaction of 2,7-bpfn affords two-dimensional rhombus grid sheets and grid sheets with dumbbell-shaped cavities. This diversity of network topologies is induced by interactions between the guest molecules and the flexible ligand frameworks. 相似文献