Synthesis and Structures of Palladium and Platinum A-Frame Complexes Bridged by a Novel Binucleating Ligand,N,N‘-Bis[(2-diphenylphosphino)phenyl]- formamidine

Abstract

A novel binucleating ligand, N,N‘-bis[(2-diphenylphosphino)phenyl]formamidine (Hdpfam), has been prepared and utilized for the synthesis of homo- and heterobimetallic palladium/platinum complexes M2R2(μ-X)(μ-dpfam) (M = Pd, Pt; R = Me, p-Tol, Cl; X = Cl, Br, I; dpfam = N,N‘-bis[(2-diphenylphosphino)phenyl]formamidinate). Treatment of Hdpfam with 2 equiv of MRX(tmeda) or MRX(cod) in the presence of tmeda produced the homobimetallic complexes. The heterobimetallic complex PdPtMe2(μ-Cl)(μ-dpfam) was obtained by the reaction of PdMeCl(cod) with PtMe(dpfam), which was produced from PtMe2(cod) and Hdpfam. The crystal structures of Pd2Cl2(μ-Cl)(μ-dpfam) and Pt2Me2(μ-Cl)(μ-dpfam) have been determined by X-ray analysis. The results indicate that both complexes have P−M−Cl−M−P A-frame structures, in which each metal center has a slightly distorted square-planar geometry and the nonbridging σ-donor ligands (Cl or Me) and μ-Cl are in a cis orientation. Treatment of Pt2Me2(μ-Cl)(μ-dpfam) with NaBH4 gave the hydride-bridged complex Pt2Me2(μ-H)(μ-dpfam).

Rational Synthesis of Supramolecular Assemblies Based on Tetraplatinum Units: Synthesis, Characterization, and Selective Substitution Reactions of Four Different Pt4 Clusters

“…Other reagents purchased from commercial sources were used without further purification. [Pt 4 A C H T U N G T R E N N U N G (m-OCOCH 3 ) 8 ] (1), [27, 28a] N,N'-bis(para-substituted aryl)-formamidine (para-substituted aryl = C 6 H 4 OMe-4, C 6 H 4 COMe-4, C 6 H 4 Cl-4, and C 6 H 4 Me-4), [39b] cis-[Pt 4 A C H T U N G T R E N N U N G (m-OCOCH 3 ) 6 (k 4 -N 4 -DArBp)] (9: DArBp = 1,3-bis(arylbenzamidinate)propane), [30] and N,N'-bis[(2-diphenylphosphino)phenyl]formamidine [33,43] were prepared according to previously published procedures. A Varian Mercury-300 Fourier transform spectrometer or BRUKER AVANCEIII-400 spectrometer were used for NMR spectroscopy and all spectra were recorded at 35 8C unless mentioned otherwise: 1 H and 13 C NMR spectra were referenced to internal solvent and corrected for TMS, and 31 P{ 1 H} NMR spectra were referenced to an external reference of 85 % H 3 PO 4 (d = 0.00).…”

Chemistry and Biological Activity of Platinum Amidine Complexes

“…[13,14] Flexible formamidinato ligands have been used as unique tools to study monodentate, bridging, and chelating arrangements in platinum derivatives, depending on the reaction conditions and the electronic properties determined by the nature of the substituents on the nitrogen and methine carbon atoms (Scheme 1). [15] A wide variety of bimetallic palladium and platinum complexes with bridging amidinato ligands have been reported and structurally characterized, [16,17] including chelated [18] and orthometallated [19] systems. The metal-amidine systems of type B can be formed through nucleophilic addition of protic N-nucleophiles, HNR 1 R 2 (such as ammonia or primary and secondary amines) to coordinated nitriles, as illustrated in Scheme 2.…”

Synthesis and Structural Diversity of Mono‐, Di‐ and Trinuclear Complexes with N,N′‐Bis[(2‐diphenylphosphanyl)phenyl]formamidine

“…[1][2] A variety of bridging ligands, such as bis(diphenylphosphanyl)methane, (diphenylphosphanyl)-pyridine, and various P 2 N 2 -type ligands have been developed extensively over the past decades. [3,4] In an effort to design novel bimetallic complexes, we recently explored a class of dinucleating N-heterocyclic carbene ligands spanned by pyrazoles (CNNC) and reported corresponding bimetallic complexes.…”

“…[5] As an extension of these efforts, our attention was drawn to the N,NЈ-bis[(2-diphenylphosphanyl)phenyl]formamidine (pnnp) ligand recently disclosed by Tsukada for dinuclear Pt 2 , Pd 2 , and PtPd complexes. [1] Tsukada has investigated these complexes for a variety of organic transformations including arylation of alkynes and alkyne/alkene coupling reactions. [2m,6] An appealing feature of this ligand is the ability to introduce [ (pnnp)FeCl 2 (7), respectively.…”

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The synthesis, characterization, and coordination chemistry of a series of mono-, di-, and trinuclear homo-/heterometallic complexes with the dinucleating ligand, N,NЈ-bis [(2-diphenyl-phosphanyl)phenyl]formamidine (pnnp) [1] are reported. Treatment of (pnnp)PdMe (1)

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