Observations on the Mechanism of Halogen-Bridge Cleavage by Unidentate Ligands in Square Planar Palladium and Platinum Complexes

Abstract

Cyclo-palladation and -platination of nitrogen donor ligands lead to insoluble p-chloro dimers which give p-bromo and p-iodo dimers on metathesis with the appropriate lithium halide. Addition of pyridine or 2,6-dimethylpyridine to the cyclopalladated dimers gives monomeric complexes with the halogen trans to the metal-carbon bond, whereas addition of 2,6-dimethylpyridine to the cycloplatinated complexes gives the isomer with the halogen cis to the metal-carbon bond. The results are discussed in terms of the mechanism of the bridge cleavage reaction.

Photoluminescent properties of heteroleptic cyclometalated platinum(II) complexes bearing 1,3-bis(3,4-dibutoxyphenyl)propane-1,3-dionate as an ancillary ligand

“…They obtained a series of (HC 4 N)PtCl(C 4 N)-type complexes in good yields using an excess amount of HC 4 N to K 2 PtCl 4 (2.5 equiv. ), although the mononuclear complex was reported as a side-product in the 1:1 reaction of K 2 PtCl 4 and 2-phenylpyridine to produce the m-chloro dimer [23]. We confirmed the structures of Pt-3a-f by 1 H NMR and MALDI-TOF mass spectra, as well as by elemental analysis.…”

Cyclometalated platinum complexes: High-yield synthesis, characterization, and a crystal structure

“…2-4 are new compounds (although the products of the reaction of H-4,6-dfppy and Hbtp with K 2 PtCl 4 under conditions identical to ours have previously been reported, without characterizing data, to be [Pt(C Ù N)(lCl)] 2 dimers [3], as has the product of Hppy and K 2 PtCl 4 ). 1 has previously been characterized as a significant side-product of the reaction of 1:1 K 2 PtCl 4 and Hppy (1:1 dioxane/water; 72 h at room temperature; 72 h at reflux) to give [Pt(ppy)(l-Cl)] 2 [7]; it has also been obtained in 59% yield from the reaction of Pt(COD)Cl 2 with excess Hppy in the presence of NaOAc in 95% ethanol [8], in 40% yield from the reaction of [Et 4 N] + [Pt(NH 3 )Cl 3 ] À and Hppy in water [5], and as a minor side-product in a synthesis of [Bu 4 N] + [Pt(ppy)Cl 2 ] À [9].…”

Synthesis and reactivity of palladium(II) fluoride complexes containing nitrogen-donor ligands

“…The palladium(II) iodide precursors, in turn, were prepared using three different synthetic strategies that are summarized in Scheme 1. The cyclometalated C~N complexes 2 – 5 were generated by reaction of the readily available cyclopalladated dimers [(phpy)Pd(I)] 2 9 ( 1a ) and [(bzq)Pd(I)] 2 ( 1b ) (phpy = 2-phenylpyridine; bzq = benzo[ h ]quinoline) with 2,6-lutidine, 4- tert -butylpyridine ( t Bu-py), or PPh 3 , respectively. Complex 6 was accessed by reaction of the known pincer complex (NCN)Pd(Br)10 (NCN = N,N,N',N' -tetramethyl-1,3-xylylenediamine) with NaI.…”