106335-98-2Relevant academic research and scientific papers
Mechanistic aspects of the cyclometalation of quinoline-8-carboxaldehyde with platinum(II)
Anklin, Clemens G.,Pregosin, Paul S.,Wombacher, Franz J.,Rüegg, Hubert J.
, p. 1953 - 1958 (2008/10/08)
Rates of reaction at 61°C in CDCl3 for the cyclometalation of quinoline-8-carboxaldehyde (1) with trans-PtCl2(1)L (L = PEt3, PBun3, PPh3, PTol3, AsEt3, AsPri3, AsTol3) are reported. Starting from trans-PtCl2(1)(PEt3), there is a kinetic isotope effect kH/kD = 1.4. Modification of the Pt(II) complex to trans-PtBr2(1)L enhances the rate by a factor of ca. 70. The use of sym-trans-[Pt(μ-Cl)(SnCl3)(PTol3)]2 and 2 equiv of 1 affords facile cyclometalation at room temperature within the mixing time. The direct generation of cationic complexes via cis-PtCl2L2 plus Ag(CF3SO3) followed by addition of 1 is also shown to lead to facile cyclometalation. All of these reactions are discussed in terms of the importance of cationic metal compounds. Synthetically, the most efficient cyclometalation of 1 can be accomplished by using [Pt(μ-Cl)(η3-CH2C(CH3)CH 2)]2. 1H and 31P NMR data are given for selected examples.
Preparative and 1H NMR spectroscopic studies on palladium(II) and platinum(II) quinoline-8-carbaldehyde (1) complexes. X-ray structures of the cyclometalated acyl complex PdCl(C(O)C9H6N) (PPh3)·PPh3 and trans-PtCl2(1)(PEt3)
Albinati,Anklin,Ganazzoli,Rüegg,Pregosin
, p. 503 - 508 (2008/10/08)
A series of complexes of the type trans-PtCl2(quinoline-8-carbaldehyde)L (2; L = PEt3, PTol3 (Tol = p-CH3C6H4), PPh3, AsMe3, AsEt3, As-i-Pr3, As-n-Bu3, AsTol3, AsMePh2) have been synthesized and characterized. The aldehyde proton couples to 195Pt with a value between 12.4 and 19.7 Hz. We interpret these NMR spectroscopic data as implying a weak Pt←H-C(O) interaction that is not of the previously reported agostic type. Complexes 2 cyclometalate at the aldehyde carbon in refluxing CHCl3. The structure of an intermediate of type 2, with L = PEt3, has been determined. Complex 2a has a square-planar trans geometry with the C-H vector of the aldehyde pointing toward the platinum and the aldehyde oxygen away from the metal center. The molecule is monoclinic, space group P21/c, with a = 14.411 (3) ?, b = 9.172 (2) ?, c = 15.217 (4) ?, β = 107.07 (2)°, V = 1929.5 ?3, and Z = 4. The X-ray structure of the palladium acyl complex PdCl(C(O)C9H6N)(PPh3)·PPh3 (3) is reported. The molecule has a square-planar coordination sphere with the acyl carbon trans to Cl and phosphorus trans to the quinoline nitrogen. A molecule of PPh3 is trapped in the crystal lattice. The molecule crystallizes in the space group P21/c, with a = 10.159 (4) ?, b = 18.262 (5) ?, c = 21.171 (5) ?, β = 103.27 (3)°, and Z = 4. The long Pd-Cl bond separation of 2.421 (2) ? is in keeping with a large trans influence for the acyl function.
