Different structural preference of Ag(i) and Au(i) in neutral and cationic luminescent heteropolynuclear platinum(ii) complexes: Z (U)-shaped Pt₂M₂ type vs. trinuclear PtM₂ type

Abstract

The reactions of monocationic Pt(II) complexes bearing N^C chelate ligands and Me2pzH, [Pt(N^C)(Me2pzH)2]PF6 (N^C = 2-phenylpyridinate (ppy(-)), 2-(2,4-difluorophenyl)pyridinate (dfppy(-)), benzo[h]quinolinate (bzq(-)); Me2pzH = 3,5-dimethylpyrazole), with Ag(I) ions gave Z (or U)-shaped neutral tetranuclear Pt2Ag2 complexes [Pt2Ag2(N^C)2(Me2pz)4], while those with Au(I) ions gave neutral trinuclear PtAu2 complexes [PtAu2(N^C)(Me2pz)3]. On the contrary, the reactions of the dicationic Pt(II) complex bearing a N^N chelate ligand and Me2pzH, [Pt(bpy)(Me2pzH)2](PF6)2 (bpy = 2,2'-bipyridine), with Ag(I) and Au(I) ions both gave Z (or U)-shaped dicationic tetranuclear Pt2M2 complexes, [Pt2M2(bpy)2(Me2pz)4](PF6)2 (M = Ag, Au). The structures of heteropolynuclear Pt(II) complexes were dominated by the nature of incorporated group 11 metal ions and the charge of complexes.

The Use of Cyclometalated NHCs and Pyrazoles for the Development of Fully Efficient Blue PtII Emitters and Pt/Ag Clusters

“…The Ag center of each subunit completes its coordination environment with a N of a 3,5‐Me 2 pz belonging to the other Pt subunit with N‐Ag‐N angles close to 180°. Both silver centers interact with each other, with the Ag⋅⋅⋅Ag distance being 3.2171(9) Å, quite similar to those observed in other pyrazolate‐bridged Pt/Ag clusters, which is indicative of argentophilic interactions …”

“…The angle between the Pt−Ag vector and the platinum coordination plane (35.62°) in addition to the Pt−Ag distance are indicative of Pt→Ag dative bonds . This Pt−Ag distance is shorter than those observed in the related tetranuclear clusters [Pt 2 Ag 2 (N^C) 2 (Me 2 pz) 4 ] 0, 2+ (N^C=ppy‐, dfppy, bpy, d Pt−Ag >3.4 Å) . The Ag center of each subunit completes its coordination environment with a N of a 3,5‐Me 2 pz belonging to the other Pt subunit with N‐Ag‐N angles close to 180°.…”

“…Moreover, mononuclear pyrazole complexes are of interest in molecular architecture and luminescence. Pt II complexes, such as [Pt(C≡CPh) 2 (RpzH) 2 ], [Pt(C^N)(RpzH) 2 ](PF 6 ), [Pt(N^N)(RpzH) 2 ](PF 6 ) 2 , [PtCl(3,5‐Ph 2 pzH) 3 ]Cl, [PtCl(3,5‐Ph 2 pz)(3,5‐Ph 2 pzH) 2 ], [Pt(3,5‐Ph 2 pz)(3,5‐Me 2 pzH)(3,5‐Ph 2 pzH) 2 ]Cl, and [Pt(3,5‐Me 2 pzH) 4 ]Cl 2 are easily deprotonated and have been used as synthons for the synthesis of a great variety of homo‐ and hetero‐polynuclear ([PtM 2 ], [Pt 2 M 2 ], M=Ag, Au) compounds. The 1,2‐dihaptobridging Rpz ligands can hold metal atoms in close proximity while permitting a wide range of structures and intermetallic separations, with the strength of the metallophilic interactions affecting the emissive properties …”

Emissive Supramolecular Systems Based on Reversible Bond Formation and Noncovalent Interactions

“…Pt(II) complexes bearing a and chelate ligand, such as 2‐phenylpyridinate (ppy), 2‐(2,4‐difluorophyenyl)pyridinate (dfppy), benzo[ h ]quinolinate (bzq), and 2,2’‐bipyridine (bpy), [11] defined cis‐configuration of pyrazole ligands to build up a new class of heteropolynuclear Pt(II) complexes involving heterometallic metal‐metal interactions. The Pt(II) complex having a chelate ligand, [Pt( )(Me 2 pzH) 2 ]PF 6 ( 13 ) reacted with AgBF 4 in the presence of Et 3 N to afford neutral Pt 2 Ag 2 species, that existed as a 1 : 1 mixture of two geometrical isomers in solution as confirmed by NMR studies (Figure 4).…”

“…We have devoted to design, synthesis and photophysical studies of luminescent molecular systems based on reversible bond formation and non‐covalent interactions. Initial studies have been focused on platinum‐based heteropolynuclear metal cluster systems involving homo‐ and heterometallic metal‐metal interactions, which can control their structure and photophysical properties by a variation of suitable organic ligands [8–13] . Recently, we have developed a luminescent host‐guest system consisting of coordination compounds and a hydrogen‐bonded capsule, whose noncovalent interactions between the host and the guests can also modulate photophysical properties of the guests [14–16] .…”