Unique Fluxional Behavior. Synthesis, Structure, and Properties of Novel (Diamine)platinum(II) Complexes of 9-Fluorenylidene- and Benzhydrylidenemalonate Ligands

Abstract

New (diamine)platinum(II) complexes A(2)PtX(2) (A(2) = trans-(+/-)-1,2-diaminocyclohexane (DACH), tetrahydro-4H-pyran-4,4-diylbis(methylamine)(THPDMA); X(2) = 9-fluorenylidenemalonate(FM), benzhydrylidenemalonate(BHM)) have been synthesized and characterized by means of multinuclear NMR spectroscopy and X-ray analysis. (DACH)Pt(FM) crystallizes in space group P2(1)/c with eight formula units in a cell of dimensions a = 20.071(7) Å, b = 12.717(3) Å, c = 24.512(6) Å, beta = 103.25(2) degrees, and V = 6090(3) Å.(3) (DACH)Pt(BHM) crystallizes in space group P&onemacr; with four molecular units in a cell of dimensions a = 11.048(3) Å, b = 13.639(3) Å, c = 14.043(6) Å, alpha = 90.17(3) degrees, beta = 91.31(4) degrees, gamma = 89.98(3) degrees, and V = 2116(1) Å(3). The platinum atom in both complexes adopts a typical square planar arrangement with two nitrogen atoms in cis position. The 9-fluorenylidene and benzhydrylidene groups of the amine ligands chelated to platinum are strikingly bent up by 88.8(3) and 80.8(2) degrees, respectively, from the platinum square plane in the solid state. Variable temperature (1)H NMR spectra of the title complexes in dimethyl sulfoxide solution reveals that the amine proton resonances are sensitive to the fluxional motion of the remote arylidene groups, and suggests that interconversion occurs between two "bent-up" and "bent-down" forms. The prominent difference between the FM and BHM complexes is observed in solution, due to the presence or absence of the angle constraint of the anionic coligands.

Solvent Effects on Coordination Chemistry – Stepwise Synthesis and Structural Properties of Monometallic Palladium(II) Complexes and Bimetallic Palladium(II)/Platinum(II) Complexes

“…Its amine proton resonance is clearly observable at δ = 4.70 and 4.82 ppm at room temperature, but as the sample temperature is increased, the resonance peaks become broadened, coalescing at 60 °C. In particular, the fact that there are two coalescing temperatures ( T c = 5 °C, Δ G ≠ = 13.8 kcal/mol; T c = 60 °C, Δ G ≠ = 16.6 kcal/mol)12 implies that interconversion occurs through an asymmetric fluxional process 4c. Further studies on analogues will provide more detailed information on the pervasive influences and applications of task‐specific bimetallic molecular materials.…”

Linkage Isomerism Dependent on Solvent and Temperature. Synthesis and Structural Properties of Diamineplatinum(II) Complexes of Allyl- and Diallylmalonate Ligands

“…In some cases, the steric factor may play an important role in determining the relative stability of linkage isomers. For the series of A 2 PtL 2 (A 2 = diamine, L 2 = anionic leaving group), the chelation modes of the anionic ligands were found to be strongly dependent on the antitumor activity and pharmacokinetic stability. − According to our previous work, a unique isomerism between (O,S)- and (S,S‘)-chelates was observed for (DACH)Pt(DTEYM). , Such a variety of chelation modes stimulated our interest in understanding the coordination chemistry of platinum complexes.…”

Solvothermal synthesis, structure and photoluminescent properties of europium complex based on fluorene derivatives

“…A fluorene and its derivatives, important components (1.0-2.0%) in high-temperature tar of the petrochemicals as the effective precursor in the biosynthesis and industrial synthesis [1,2], play a unique role in photoluminescent and electroluminescent materials for recent decades and have drawn much attention of materials chemists and devices physicists [3][4][5][6]. Fluorene derivatives have been the starmolecules in the organic luminescent materials as well as one of the research focus and forefronts in the optoelectronic information materials, which have rigid biphenyl aromatic moieties with a wide energy gap (N2.90 eV) in the backbones, high thermal stability and fine luminescent efficiency [7].…”