C−H Activation Induced by Water. Monocyclometalated to Dicyclometalated: C∧N∧C Tridentate Platinum Complexes
摘要:
Metalation of 2,6-diphenylpyridine (1) by potassium tetrachloroplatinate in acetic acid gives a monocyclometalated chloride-bridged dimer 4. This dimer is split with CO to give a kinetic product st with the incoming CO trans to the orthometalated carbon. The kinetic product of cleavage is shown to be 16 kJ mol(-1) higher in energy than the thermodynamic product 9c, which has the CO trans to the pyridine nitrogen. The isomerization of 9t to 9c is shown not to take place via an associative mechanism and, with analogue 11, is effectively suppressed when excess chloride is added, implying that it takes place via a chloride dissociation. The monocyclometalated 9 undergoes a second cyclometalation to give the C boolean AND N boolean AND C dicyclometalated complex 15 in high yield. This second cyclometalation is brought about by the simple expedient of adding water to the monocyclometalated precursor. The addition of water is rationalized on the basis of needing to ionize the HCl byproduct of the reaction. Using a substituted pyridine (5) analogous chemistry is observed. Single-crystal X-ray structures of one of the intermediates (6) and one of the final products (15) have been solved. Density functional theory calculations are used to rationalize the isomerizations of the monocyclometalated intermediates and the need to ionize HCl in the second cyclometalation.
Molecular Recognition – Allosterism Generated by Weak Host–Guest Interactions in Molecular Rectangles
作者:James D. Crowley、Ian M. Steele、Brice Bosnich
DOI:10.1002/ejic.200500393
日期:2005.10
Two metal-based molecular rectangles that bear two identical binding sites form 1:2 host–guest adducts with a pair of analogous planar Pt2+ complexes. The larger of the two guests shows no binding allosterism with either of the two rectangles, but substantial positive allosterism is observed when the smaller guest binds to the rectangles. It is proposed that the smaller guest is better accommodated
Clippane: A Mechanically Interlocked Molecule (MIM) Based on Molecular Tweezers
作者:Susana Ibáñez、Cristian Vicent、Eduardo Peris
DOI:10.1002/anie.202112513
日期:2022.1.10
molecule in solution, in the gasphase and in the solidstate. The behavior of the tert-butyl substituted tweezer differs greatly form that shown by the tweezer lacking of these bulky groups, whose dimeric structure is in equilibrium with the monomeric structure, therefore not showing any mechanical coercion that avoids the disassembly of the self-aggregated structure.
Supramolecular Recognition Forces: An Examination of Weak Metal−Metal Interactions in Host−Guest Formation
作者:James D. Crowley、Ian M. Steele、B. Bosnich
DOI:10.1021/ic0481531
日期:2005.5.1
Molecular receptors consisting of two parallel-disposed terpy-M-Cl units (M = Pd2+, Pt2+) are used to form host-guest adducts with aromatic molecules and with neutral square-planar Pt2+ complexes. Host-guest formation is controlled by several factors including pi-pi interactions and, in some cases, weak Pt-Pt interactions between the host and the guest. This latter interaction was examined by comparing the host-guest stability of adducts formed by isoelectronic Pt2- and Au3+ complexes with the Pt2+ receptor. Consistently, the former is more stable.
Synthesis and Photophysical Properties of a Series of Biscyclometalated Platinum(II) Complexes on the Basis of a Tridentate 2,6-Diphenylpyridine
作者:M. V. Kulikova、K. P. Balashev、Kh. Erzin
DOI:10.1023/b:rugc.0000025140.64970.10
日期:2003.12
The complexes C,C-trans-[Pt(C<^>N<^>C)L](z) [C<^>N<^>C is bisdeprotonated 2,6-diphenylpyridinate (dppy(2-)); L = CO, Me2SO (dmso), ethylenediamine (en), CN-, pyrazine (pz), P(C6F5)(3), 4,4'-bipyridine (4,4'-bpy)] were synthesized and characterized by H-1 NMR, electronic, and emission spectroscopy. Spectral-luminescence properties of the chromophoric group (platinum-cyclometalating ligand) in the CC-trans-biscyclometalated complexes depend on the nature of the noncyclometalating ligand L, which is explained by its donor-acceptor effects on the form of existence of the complex in solution.
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作者:M. V. Kulikova、T. V. Taraskina、E. A. Cherezova、K. P. Balashev