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N-heterocyclic Ligand (n-heterocyclic + ligand)

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Chemistry	100%

Selected Abstracts

A Series of One- to Three-Dimensional Copper Coordination Polymers Based on N-Heterocyclic Ligands

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 12 2006
Xiang He
Abstract A family of copper coordination polymers containing different N-heterocyclic ligands, namely [Cu(CN)(dmpyz)]n (1),[Cu2(CN)2(imz)]n (2), [Cu3(CN)(trz)2]n (3), [Cu6(CN)6(dmtrz)3]n(4), [Cu2(CN)(5-metta)]n (5), [Cu2(CN)(5-phtta)]n (6), and {[Cu6(CN)6(dmtrz)]2[Cu2(CN)2(dmtrz)2]}n (7) has been prepared and structurally characterized by X-ray crystallography. The crystal structures of 1 and 2 are 1D chain frameworks. Compound 3 is a twofold interpenetrating 2D supramolecular framework in which the cyanide groups act as bridging ligands to link the copper centers into an unusual bilayer motif with large channels. Compounds 4,6 all possess 3D networks. Compound 4 is constructed by two parts: 2D rectangular-grid layers and {Cu2(CN)2(dmtrz)2} building blocks. Compound 5 is built up by X-shaped chains that connect each other in an ABAB arrangement to generate the3D network. The structure of 6 is a 3D network includingone-dimensional square-grid channels, with a shortest Cu2···Cu2A (A: ,x + 1, ,y + 1, ,z) distance of about 2.347(1) Å. Compound 7 features a peculiar 3D + 1D network in which 1D guest metal-organic polymer chains are filled in an unusual 3D architecture constructed by double helical host tubes. Compounds 1,7 show a systematic variation in dimensionality from 1D to 3D to 3D + 1D. The luminescence properties of these compounds have been also studied. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

trans -[1,3-Bis(2,4,6-trimethylphenyl)imidazolidin-2-ylidene]dichlorido(triphenylphosphine-,P)palladium(II)

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2007
Hayati Türkmen
The title complex, [PdCl2(C21H26N2)(C18H15P)], shows slightly distorted square-planar coordination around the PdII metal centre. The Pd,C bond distance between the N-heterocyclic ligand and the metal atom is 2.028,(5),Å. The dihedral angle between the two trimethylphenyl ring planes is 36.9,(2)°. [source]

Effect of the Nature of the Substituent in N -Alkylimidazole Ligands on the Outcome of Deprotonation: Ring Opening versus the Formation of N-Heterocyclic Carbene Complexes

CHEMISTRY - A EUROPEAN JOURNAL, Issue 28 2010
Miguel
Abstract Complexes [Re(CO)3(N -RIm)3]OTf (N -RIm=N -alkylimidazole, OTf=trifluoromethanesulfonate; 1,a,d) have been straightforwardly synthesised from [Re(OTf)(CO)5] and the appropriate N -alkylimidazole. The reaction of compounds 1,a,d with the strong base KN(SiMe3)2 led to deprotonation of a central CH group of an imidazole ligand, thus affording very highly reactive derivatives. The latter can evolve through two different pathways, depending on the nature of the substituents of the imidazole ligands. Compound 1,a contains three N -MeIm ligands, and its product 2,a features a C-bound imidazol-2-yl ligand. When 2,a is treated with HOTf or MeOTf, rhenium N-heterocyclic carbenes (NHCs) 3,a or 4,a are afforded as a result of the protonation or methylation, respectively, of the non-coordinated N atom. The reaction of 2,a with [AuCl(PPh3)] led to the heterobimetallic compound 5, in which the N-heterocyclic ligand is once again N-bound to the Re atom and C-coordinated to the gold fragment. For compounds 1,b,d, with at least one N -arylimidazole ligand, deprotonation led to an unprecedented reactivity pattern: the carbanion generated by the deprotonation of the C2H group of an imidazole ligand attacks a central CH group of a neighbouring N -RIm ligand, thus affording the product of CC coupling and ring-opening of the imidazole moiety that has been attacked (2,c,,d). The new complexes featured an amido-type N atom that can be protonated or methylated, thus obtaining compounds 3,c,,d or 4,c,,d, respectively. The latter reaction forces a change in the disposition of the olefinic unit generated by the ring-opening of the N -RIm ligand from a cisoid to a transoid geometry. Theoretical calculations help to rationalise the experimental observation of ring-opening (when at least one of the substituents of the imidazole ligands is an aryl group) or tautomerisation of the N-heterocyclic ligand to afford the imidazol-2-yl product. [source]