Organometallics Received May 13, 2009


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Crown Ether Palladacycles as Metalloligands: Suitable Precursors for Tetranuclear Mixed Transition/Non-Transition Metal Complexes

  • Organometallics

  • Received May 13, 2009

  • Author:Samuel Castro-Juiz,† Alberto Fernandez,† Margarita LopezTorres,†Digna Vazquez-Garcia,† Antonio J. Suarez,† Jose M. Vila,*,‡ and Jesus J. Fernandez*,

  • ††Departamento de Quimica Fundamental, Universidade da Coruna, E-15071 A Coruna, Spain (西班牙拉科鲁吉亚大学物理化学系)

  • ‡Departamento de Quimica Inorganica, Universidad de Santiago de Compostela,

  • E-15782 Santiago de Compostela, Spain(圣地亚哥大学物理化学系)




Introduction

  • The particular ability of crown ethers to complex cations has been used to study a large number of applications such as the production of sensors and the selective extraction of cations or the ionic transport in membranes. We can use them to obtain photochemical controlled and electrochemical active receptors or compounds with promising anticancer properties.

  • They may also provide a novel and interesting route to the preparation of metalloligands containing a crown ether ring systems, capable of further coordination to metal cations, producing mixed transition metal/main group metal species.



2,3,4-(MeO)3C6H2C(H)=N-[9,10-(C8H16O5)C6H3] (a):

  • 2,3,4-(MeO)3C6H2C(H)=N-[9,10-(C8H16O5)C6H3] (a):



2,3,4-(MeO)3C6H2C(H)=N[9,10-(C10H20O6)C6H3 (b).

  • 2,3,4-(MeO)3C6H2C(H)=N[9,10-(C10H20O6)C6H3 (b).



二、Synthesis of the Complexes.

  • [Pd{2,3,4-(MeO)3C6HC(H) =N-[9,10 (C8H16O5)C6H3]-C6,N}(μ-O2CMe)]2 (1a).



[Pd{2,3,4-(MeO)3C6HC(H) =N-[9,10 (C8H16O5)C6H3]-C6,N}(μ-O2CMe)]2 (1b).

  • [Pd{2,3,4-(MeO)3C6HC(H) =N-[9,10 (C8H16O5)C6H3]-C6,N}(μ-O2CMe)]2 (1b).





[(2a)Na2(ClO4)2] (6a).

  • [(2a)Na2(ClO4)2] (6a).

  • [(2a)K2(ClO4)2] (7a).

  • [(2a)(NH4)2(PF6)2] (8a).

  • [(2a)Pb2(SCN)4] (9a).

  • [(1b)K2(ClO4)2] (2b).

  • [(1b)Pb2(SCN)4] (3b).

  • [(1b)Rb2(ClO4)2] (4b).

  • [(1b)Ba2(ClO4)4] (5b).







Results and discussion

  • Microanalyses(微量分析) were carried out using a Carlo Erba(卡劳尔巴)elemental analyzer, model 1108.

  • The FAB(快原子轰击) mass spectra were recorded using a FISONS Quatro mass spectrometer with a Cs ion gun; 3-nitrobenzyl alcohol was used as the matrix.

  • IR spectra were recorded as Nujol mulls or polythene discs Nujol mulls or KBr discs on a Perkin-Elmer model 1330.

  • NMRspectra were obtained as CDCl3 solutions and referenced to SiMe4 (1H,13C{1H}) and were recorded on a Bruker AVANCE-300 spectrometer.

  • Three-dimensional, roomtemperature X-ray data were collected on a Bruker Smart 1K CCD diffractometer using graphite-monochromated Mo

  • KR radiation.



Crystal Structure of Complex 1a.

  • Crystal Structure of Complex 1a.

  • monoclinic

  • As a result of Pd(1) and Pd(2) being bridged by two mutually cis μ-acetate ligands, the chelating C,N bonded Schiff bases are forced to lie above one another in the dimeric molecule.



Each palladium atom is in a slightly distorted square-planar coordination environment.

  • Each palladium atom is in a slightly distorted square-planar coordination environment.



  • Crystal Structure

  • of Complex 6a.

  • Dimeric

  • presents a crystallographic inversion center located at the center of the Pd(μ-Cl)2Pd moiety.



the cyclometalated ligands in a relative anti disposition and the [Na(ClO4-O,O] fragments situated on opposite faces of the molecule.

  • the cyclometalated ligands in a relative anti disposition and the [Na(ClO4-O,O] fragments situated on opposite faces of the molecule.



Conclusions

  • We have shown that Schiff base crown ether palladacycles may be prepared as acetate- or chloride-bridged dimer compounds in the anti form, with 15-crown-5 or 18-crown-6 rings.

  • The ensuing complexes may accommodate two non-transition metals per dimer molecule without substantial changes in the palladacycle structure to yield mixed transition/non-transition metal complexes.

  • Alkaline and alkaline-earth metal cations, as well as lead(II) and (owing to its size) the ammonium cation, have been tested; the corresponding counteranion is bonded to the coordinated metal cation.

  • The first crystal structure of this type of mixed metal complexes is reported, as definitive proof of the molecular arrangement.




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