Observation of the Properties of a Single Unit of a Limited CDW Structure in a Pt^II/Pt^IV Host–Guest Binary System Based on a Square‐Shaped Complex

Abstract

A macrocyclic tetranuclear platinum(II) complex [Pt(en)(4,4'-bpy)](4)(NO(3))(8) (1(NO(3))(8); en = ethylenediamine, 4,4'-bpy = 4,4'-bipyridine) and a mononuclear platinum(IV) complex [Pt(en)(2)Br(2)]Br(2) (2Br(2)) formed two kinds of Pt(II)/Pt(IV) mixed valence assemblies when reacted: a discrete host-guest complex 12Br(10) (3) and an extended 1-D zigzag sheet 1(2)(3)Br(8)(NO(3))(6) (4). Single crystal X-ray analysis showed that the dimensions of the assemblies could be stoichiometrically controlled. Resonance Raman spectra suggested the presence of an intervalence interaction, which is typically observed for quasi-1-D halogen-bridged M(II)/M(IV) complexes. The intervalence interaction indicates the presence of an isolated {Pt(II)X-Pt(IV)-XPt(II)} moiety in the structure of 4. On the basis of electronic spectra and polarized reflectance measurements, we conclude that 4 exhibits intervalence charge transfer (IVCT) bands. A Kramers-Kronig transformation was carried out to obtain an optical conductivity spectrum, and two sub-bands corresponding to slightly different Pt(II)-Pt(IV) distances were observed.

Platinum(II) Monomer and Dimer Complexes with a Bis(oxazolinyl)phenyl Pincer Ligand

“…Each platinum center is bonded to a tridentate phebox – ligand and a pyridyl ligand, resulting in a distorted square planar coordination geometry similar to those found for other platinum­(II) complexes with oxazolinyl pincer ligands. ,,, The pyridyl groups are approximately perpendicular to the coordination plane, as expected for the steric demands of the oxazoline methyl groups, whose proximity restricts rotation of the pyridyl group about the Pt–N bond and results in upfield shifts in the 1 H NMR spectra. The intramolecular Pt···Pt distances for dimers 6 (7.0285(5) Å), 7b (11.3489(8) Å), and 8-c (9.1385(6) Å) and 8-p (9.1884(6) Å) are typical for these bridging ligands. ,,− In crystals of 8-p and 8-c , the 1,2-bis­(4-pyridyl)­ethane (bpa) ligand adopts the less energetically favorable gauche conformation, presumably due to packing effects. It is interesting that the Pt–N­(pyridyl) bond lengths for 1 – 8 are significantly shorter than those found for pip 2 NCN – analogues, , as well as Pt­(Me 4 NCN)­(pyOH) + . , The accumulated data indicate a stronger interaction between the platinum center and pyridyl ligand in the phebox – series and suggests that phebox – is a weaker trans/cis directing ligand than pip 2 NCN – or Me 4 NCN – .…”

Unusual platinum(III) valence state stabilized through the iodide-bridged three-center four-electron bonding

“…In contrast, disproportionation into the Pt(II/IV) states is generally observed in Pt-based halogen-bridged metal complex chains (MX-Chains). 16,17 More than 300 MX-Chains have been synthesized to date, and MX-Chains have demonstrated gigantic third-order optical nonlinear susceptibility, 18,19 electrical conductivity, [20][21][22][23] and spin properties, [24][25][26] as well as unique structures such as molecular ladders and tubes, [27][28][29][30][31] one-dimensional heterojunctions, 32 and grade-separated orthogonal structures. 1).…”