New N-heterocyclic carbene mercury(II) complexes: Close mercury–arene interaction (original) (raw)
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Bridged dinucleating N-heterocyclic carbene ligands and their double helical mercury(II) complexes
2006
A series of six 3,6-bis(imidazolium-3-yl)pyridazine derivatives with different imidazole-N substituents have been synthesized and isolated as the salts [H 2 L]Cl 2 (1a)-(6a) and [H 2 L](PF 6 ) 2 (1b)-(6b). Solid state structures have been determined crystallographically for eleven out of the twelve compounds, revealing diverse hydrogen bonding patterns that involve the imidazolium-C 2 H units and the anions. Nheterocyclic carbene (NHC) mercury(II) complexes [Hg 2 L 2 ](PF 6 ) 4 (7)-(9) are readily formed in good yields from ligand precursors [H 2 L](PF 6 ) 2 and Hg(OAc) 2 , as long as imidazole-N substituents are not too bulky. X-ray crystallography reveals double helical bimetallic arrangements for the stable [Hg 2 L 2 ] 4+ cations. Ligand scrambling in [Hg 2 L 2 ] 4+ occurs only in the presence of free carbene precursor, presumably via an associative mechanism.
Reaction of [Hg(OAc)2] with two mole proportion of LH(LH= benz-1,3-imidazoline-2-thione, benz-1,3-oxazoline-2-thione or benz-1,3-thiazoline-2-thione ) in the presence Et3N gave linear complexes of the type [HgL2]. Treatment of [HgL2] with two mole proportion of PPh3 or one mole proportion of the diphosphine Ph2P(CH2)nPPh2 gave tetrahedral complexes of the type [HgL2(PPh3)2], [HgL2(m-diphos)]2 (n=1) or [HgL2(diphos)] (n = 2 or 3) respectively, While treatment with two mole proportion of Ph2PCH2PPh2 (dppm) gave octahedral complexes of the type[HgL2(dppm)2]. The preparated complexes have been characterized by mean of elemental analysis, molar conductance, i.r. spectral data, 1H, 13C-{1H}, 31P-{1H} n.m.r. data. Single crystal x-ray analysis of two of the complexes ( 11 and 13 ) has reveled the presence of a tetrahedral coordination geometry about mercury.
Mercury complexes with the ligand benzaldehyde-N(4),N(4)-dimethylthiosemicarbazone
Inorganica Chimica Acta, 2010
The Schiff base benzaldehyde-N(4),N(4)-dimethylthiosemicarbazone (LH) and its complexes [Hg(NO 3 ) (LH) 2 ]NO 3 (1), [Hg(L) 2 ] (2), [Hg(LH) 2 (l-X) 2 HgX 2 ] [X = Cl (3), Br (4)], [HgI(LH)(l-I) 2 HgI(LH)] (5) and [HgI 2 (LH)] (6) have been synthesized and characterized by IR, mass spectrometry, 1 H and 13 C NMR and by single crystal X-ray diffraction. All the complexes were obtained in ethanol and complex 2, in which the ligand is deprotonated, in addition needs the presence of basic medium. From mercury(II) iodide two complexes with the same molar ratio but with different structures were isolated. In all the complexes the ligand acts as a NS chelate, except in complex 5 in which is only S-donor. The coordination number of the mercury ion and the structures of the complexes depend on the counterion. Complexes 1, 2 and 6 are monomeric species but with different coordination spheres: N 2 S 2 O 2 with a distorted octahedral arrangement in complex 1, and N 2 S 2 or NSI 2 in a pseudo-tetrahedral geometry in complexes 2 and 6, respectively. However, 3, 4 and 5 are binuclear complexes with two halido bridges, but they show two different structures. In 3 and 4, each mercury ion has a different environment giving an asymmetric structure, one is bonded to two NS-ligands and two halido bridges in a distorted octahedral geometry, and the other one has a tetrahedral environment formed by four halido ligands. In complex 5 both mercury ions are equivalent with a SI 3 distorted tetrahedral coordination sphere, formed by one S-bonded ligand, one terminal iodido and two iodido bridges.
Main Group Metal Chemistry, 2009
A series of new and novel complexes of the types [(Cl)Hg(L)] and [Hg(L) 2 ] [where L= Schiff bases; salicylidene-2-methyl-l-aminobenzene (smabH) and vanilidene-1-aminobenzene (vabH)] of mercury(II) have been synthesized by the interactions of mercury(II) chloride with sodium salts of Schiff bases in the presence of THF-MeOH mixture, in 1:1 and 1:2 molar ratio(s) respectively, to produce complexes; [(μ-Cl) 2 Hg 2 (smab) 2 ] (1), [Hg(smab) 2 ] (2), [(μ-01) 2 Η 82 (ν 3^2 ] (3) and [Hg(vab) 2 ] (4). Further, complex [(μ-Cl) 2 Hg 2 (smab) 2 ] (1) has been treated with various aryloxo-, alkoxo-, tetraisopropoxyaluminate, benzoxazolato-and benzimidazolato-salts of sodium in equimolar ratio, to produce new mixed ligand complexes such as, [^-OAr) 2 Hg 2 (smab) 2 ](5), [^-OPr^Hg^smab^] (6), [{(μ-ΟΡ0 2 Α1(ΟΡι0 2 }Ι^(8ΐτκώ)] (7), [{n 2-(pbox)}Hg(smab)] (8) and [{n. 2-(pbz)}Hg(smab)] (9). These complexes have been characterized by elemental analysis (Hg, Cl, C, Η & Ν), melting points and spectral (UV-vis, FT-IR, Ή-, I3 C-NMR and FAB-MS) data, whereas the structure of the complexes have been tentatively determined by FAB-MS spectral studies. A thermogravimetric analysis (for complex 4) and X-ray powder diffraction studies (for complex 3) are also reported herein.
Synthesis and Characterization of New Silver(I)- and Mercury(II)-N-Heterocyclic Carbene Complexes
Australian Journal of Basic and Applied Sciences
New silver(I)- and mercury(II)-N-heterocyclic carbene (NHC) complexes were prepared from the reaction of the imidazolium salts with silver(I) oxide and mercury(II) acetate . The prepared complexes were characterized by 1 H and 13 C NMR, elemental analysis (CHN) and X-ray crystallography for one of the silver complexes. The metal centers are coordinated either by two NHCs giving the general formula (M-μ-L 2 , where M = silver or mercury, L = NHC), or by one NHC and one bromide.
Inorganica Chimica Acta, 2008
Reaction of HgCl 2 with trans-(±)2-(2,5-di(pyridin-2-yl)-4,5-dihydro-1H-imidazol-4-yl)pyridine (L1) and cis-(±)-(phenyl(2,4,5tri(pyridin-2-yl)-4,5-dihydroimidazol-1-yl)methanone (L2) gives mononuclear complexes, 1 and 2. In these complexes L1 and L2 behave as tridentate and bidentate chelating ligands, giving distorted trigonal bipyramidal and tetrahedral coordination geometries, respectively. X-ray diffraction studies revealed a series of N-HÁ Á ÁCl, C-HÁ Á ÁCl, C-HÁ Á ÁN and C-HÁ Á Áp interactions in 1 giving a 3D network, and N-HÁ Á ÁCl, C-HÁ Á ÁCl, C-HÁ Á Áp and pÁ Á Áp interactions in 2 giving a 2D network in the crystal lattice. Since both ligands should have a similar binding capacity to the mercury ions, the variations observed for coordination number and geometry should be a consequence of supramolecular stabilizing effects.
Zeitschrift für anorganische und allgemeine Chemie, 2012
The title ligand, [1-(2-methoxyphenyl)-3-(4-chlorophenyl)]triazene, HL (1), was prepared. In a reaction with Hg(NO 3) 2 it forms the complex [Hg(C 26 H 22 Cl 2 N 6 O 2)], [HgL 2 ] (2). Both compounds were characterized by means of X-ray crystallography, CHN analysis, FT-IR, 1 H NMR, and 13 C NMR spectroscopy. In the structure of compound 1, two independent fragments are present in the unit cell. They exhibit trans arrangement about the-N=N-double bond. The dihedral angles between two benzene rings in both fragments are 4.36 and 18.79 Å, respectively. Non-classic C-H•••N hydrogen bonding and
Polyhedron, 2009
Several mercury(II) complexes of 2-quinaldic acid (quinH; IUPAC name: quinoline-2-carboxylic acid) were synthesized and characterized. [Hg(quin) 2 (OH 2 )] (1) was obtained as the reaction product of mercury(II) chloride and 2-quinaldic acid in an aqueous media, while a mixture of 1, [(quinH 2 )(HgCl 3 )]Á 2quinHÁH 2 O (2), and [Hg(quin) 2 (EtOH)]ÁH 2 O (3) was obtained from a 96% ethanol solution. Pure [HgCl(quin)(quinH)] (4) was obtained as the first reaction product when the reaction was performed in absolute alcohol. After isolation of 4 from the filtrate the mixture of 1-3 was again obtained. The Xray single-crystal structure analysis reveals that the ligand, 2-quinaldic acid is coordinated to the Hg 2+ ion as a N,O-chelating quinaldate ion in structures 1, 3 and 4. In the structure of 2 polymeric ½HgCl 3 n nÀ anions are formed with a very deformed trigonal-bipyramidal 3 + 2 mercury coordination sphere while the ligand, 2-quinaldic acid exists in the zwitterionic form as quinH, and as a cation, quinH 2 þ . The coordination polyhedron in 1 and 4 can be described as 2 + 3 and 4 + 1 deformed trigonal-bipyramidal and square-pyramidal geometry with the water molecule and chlorine atom at the fifth site in 1 and 4, respectively. The coordination sphere in 3 is square-pyramidal with the ethanol molecule at the vertex, however through additional HgÁÁÁO contacts centrosymmetric dimers are formed resulting in a 5 + 1 effective octahedral mercury coordination.