Cationic Unsymmetrical 1,4-Diazabutadiene Complexes of Platinum(II)

Abstract

The synthesis of the silyl-protected 1,4-diazabutadiene ligands glyoxal-bis((2-R-triisopropylsiloxymethyl)-6-methylphenyl)diimine (TIPS-6-MPD) and glyoxal-bis((2-R-triisopropylsiloxymethyl)-4-methylphenyl)diimine (TIPS-4-MPD) and their subsequent reactions with trans-Pt(SMe 2 ) 2 (Me)Cl to generate the corresponding complexes (TIPS-6-MPD)Pt(Me)Cl (1a) and (TIPS-4-MPD)Pt(Me)Cl (1b) are described. Cationic complexes of the type [(N,N-chelate)-Pt(Me)(L)]BF 4 (where L ) solvent/olefin and N,N-chelate ) TIPS-6-MPD and TIPS-4-MPD) are generated by the reaction of chloro methyl complexes 1a and 1b with AgBF 4 in the presence of L. Various exchange reactions were examined for [(TIPS-6-MPD)Pt(Me)(NCCH 3 )]-BF 4 ( 2a), in which it was determined that the coordinated solvent reversibly exchanges with acrylonitrile, ethylene, fumaronitrile, cis-pentenenitrile, benzonitrile, dimethyl sulfide, and carbon monoxide to generate the corresponding cationic complexes 3-9, respectively. Kinetics experiments under pseudo-first-order conditions using 10-, 20-, and 30-fold excesses of benzonitrile demonstrate that 2a undergoes ligand exchange via an associative pathway with a bimolecular rate constant k 2 of (3.2 ( 2.0) × 10 -4 M -1 s -1 . Complex 2a was found to initiate the polymerization of various electron-rich monomers. A detailed analysis of the reaction demonstrates that the initiation is cationic in nature. The molecular structure of TIPS-6-MPD has been determined by a single-crystal X-ray diffraction analysis. The free ligand adopts an s-trans conformation with a planar NdCsCdN backbone.

Extending The Reaction Landscape of the {Pt(μ‐S)2Pt} Core: From Metal Centers to Non‐Metallic Electrophiles

“…[11] In contrast with the general behavior of cationic olefin complexes of platinum, [57,58] the synthesized complexes did not undergo spontaneous loss of the unsaturated ligand and thus allowed exploration of their reactivity towards a strong nucleophile such as soExtending The Reaction Landscape of the {Pt(µ-S) 2 dium methoxide (Scheme 9). Remarkably, unlike previous reports on the attack of NaCH 3 O on the {Pt(cod)} II fragment, [59][60] the above reactions did not promote the nucleophilic attack of the methoxide anion, but only deprotonation of cod, thus leading to [{Pt 2 (µ 3 -S) 2 (dppp) 2 }-Pt(C 8 H 11 )]Cl, [{Pt 2 (µ 3 -S) 2 (cod)(C 8 H 11 )}Pt(dppp)]Cl and [{Pt 2 (µ 3 -S) 2 (C 8 H 11 ) 2 }Pt(dppp)].…”

DFT-Assisted Design and Evaluation of Bifunctional Amine/Pyridine-Oxazoline Metal Catalysts for Additions of Ketones to Unactivated Alkenes and Alkynes

“…In the case of ethylene, a peak with a mass corresponding to octene was detected in the GC-MS. Pt(II) and Pd(II) salts are known to promote the polymerization of alkenes. [35] [36] [37] A reaction screen for the addition of cyclopentanone to 6-phenyl-2-hexyne was also performed, but also yielded only peaks for the starting materials in the GC-MS. Due to the limited solubility of some of the nickel metal salts and Pd(OAc)2 with our precatalyst in MeNO2, we chose to exclude these metal salts in our additional screens. Mixtures of methyl acetoacetate with ethylene (13), 4-(4-fluorophenyl)-1-butene (12), or 6-phenyl-2-hexyne (16) were screened with precatalyst 1 and either palladium or platinum metal salts (Table [4]).…”

Synthesis and Reactivity of Square‐Planar PtII–η1‐Hydrocarbyl Complexes Containing cis‐Coordinated Olefin or Alkyne

“…Unsymmetrical N,N-chelates were used to isolate ethylene and acrylonitrile complexes I-34 to I-36, by using a procedure analogous to that reported in Scheme 5. [17,18] Alternatively, the same complexes were obtained by reacting the dimethyl precursor with B(C 6 F 5 ) 3 , giving rise to B(C 6 F 5 ) 3 -www.eurjic.org…”