N,N‘-Dialkylimidazolium Chloroplatinate(II), Chloroplatinate(IV), and Chloroiridate(IV) Salts and an N-Heterocyclic Carbene Complex of Platinum(II):  Synthesis in Ionic Liquids and Crystal Structures

Abstract

The first imidazole-type carbene complex of platinum(II), cis-(C2H4)(1-ethyl-3-methylimidazol-2-ylidene)PtCl2, has been obtained by reacting PtCl2 and PtCl4 with ethylene in the basic [EMIM]Cl/AlCl3 (1.3:1) ionic liquid (where [EMIM]+ = 1-ethyl-3-methylimidazolium) at 200 degrees C and structurally characterized (monoclinic P21/c space group, a = 10.416(2) A, b = 7.3421(9) A, c = 15.613(2) A, beta = 101.53(2) degrees, Z = 4). This complex can be regarded as a stable analogue of the pi-alkene-Pd(II)-carbene intermediate in the Heck reaction. In addition, a series of new N,N'-dialkylimidazolium salts of platinum group metals of the type [RMIM]2[MCln], where [RMIM+] = 1-alkyl-3-methylimidazolium and M = Pt(II), Pt(IV), or Ir(IV), have been prepared and characterized. The salts [EMIM]2[PtCl6] (1) and [EMIM]2[PtCl4] (2) were prepared in the ionic liquid [EMIM]Cl/AlCl3 and the salts [BMIM]2[PtCl4] (3) and [BMIM]2[PtCl6] (4) (where [BMIM]+ = 1-n-butyl-3-methylimidazolium) and [EMIM]2-[IrCl6] (5) in aqueous or acetonitrile media. From TGA measurements, salts 1-5 decompose in air in several steps eventually to form the corresponding metal, the onset of decomposition being observed at (degree C) 260 (1), 220 (2), 200 (3), 215 (4), and 210 (5). The structures of 1, 2, and 5 were determined by single-crystal X-ray analysis. The three salts crystallize in the monoclinic P21/n space group (1, a = 7.6433(9) A, b = 16.353(2) A, c = 9.213(1) A, beta = 113.56(1) degrees, Z = 2; 2, a = 8.601(1) A, b = 8.095(2) A, c = 13.977(2) A, beta = 91.75(2) degrees, Z = 2; 5, a = 10.353(2) A, b = 9.759(2) A, c = 10.371(2) A, beta = 92.98(3) degrees, Z = 2).

A Tris(carbene) Pincer Complex: Monomeric Platinum Carbonyl with Three Bound Carbene Centers

“…[15] All of these lengths are significantly longer than those typically found for both Nheterocyclic carbene complexes of two-and four-coordinate Pt centers (1.93-1.97 ), [18][19][20] and the Fischer carbene complexes of four-coordinate Pt centers (1.87-1.96 ). [21][22][23][24][25] Indeed, the PtÀC(1) bond length in 2 is unusual in that it is more akin to those found for Fischer carbene complexes of five- [26] and six-coordinate [27] Pt centers (1.99-2.01 ).…”

Speciation of Rare‐Earth Metal Complexes in Ionic Liquids: A Multiple‐Technique Approach

“…[16] Recent studies demonstrate that also inorganic and materials chemists can take advantage of the properties of ionic liquids. [17][18][19] For instance, ionic liquids have been applied as solvents and templates to modify the morphology of inorganic nanomaterials. [20][21][22][23] Furthermore, the so-called metalcontaining ionic liquids are regarded as promising new comAbstract: The dissolution process of metal complexes in ionic liquids was investigated by a multiple-technique approach to reveal the solvate species of the metal in solution.…”

Nickel-containing di-charged imidazolium ligand with high crystalline organization. Interception and characterization of a transient carbene/cation species

“…We have recently shown that the combination of 1-n-butyl-3-methylimidazolium chloride with indium trichloride affords the air stable room emperature ionic liquid BMIÁInCl 4 that can be used as an alternative to organo-aluminate melts [5]. Others have synthesized and characterized gallium- [6], cobalt- [7], gold- [8], vanadium- [9], uranium- [10], platinum-containing melts [11]. In order to allow a rational application of such materials, a good characterization and the understanding of the supramolecular organization desired [12].…”