Quantification of Cooperativity between Metal Sites in Dinuclear Transition Metal Complexes Containing the (2‐Dimethylamino)‐4‐(2‐pyrimidinyl)pyrimidine Ligand

Abstract

A concept for the quantification of cooperative effects in transition-metal complexes is presented. It is demonstrated for a series of novel N,N-(mononuclear) and C,N-coordinated homo-and heterometallic binuclear complexes based on the (2-dimethylamino)-4-(2-pyrimidinyl)pyrimidine ligand, which are accessible by applying roll-over cyclometallation. These iridium-, platinum-, and palladium-containing compounds are investigated with respect to their absorption and fluorescence spectra. The cooperative effects in the electronic absorptions, i. e., the energetic shifts between mononuclear and dinuclear complexes, and free ligands are analyzed on the basis of the lowest energy π-π* transitions and compared to calculated data, obtained from TD-DFT calculations. Furthermore the corresponding fluorescence spectra are presented and analyzed with respect to the concept of cooperativity.

Time‐Resolved Spectroscopy and Electronic Structure of Mono‐and Dinuclear Pyridyl‐Triazole/DPEPhos‐Based Cu(I) Complexes

“…The magnitude of the observed luminescence shifts is of the order or even larger than the effects obtained, for example experimentally for dinuclear iridium, palladium and platinum containing transition metal complexes with (2‐dimethylamino)‐4‐(2‐pyrimidinyl)pyrimidine ligands. [39b] …”

Synthesis and photophysical properties of multimetallic gold/zinc complexes of (P,N,N,N,P) and (P,N,N) ligands

“…Furthermore, an analysis of the ground and excited state concerning eqn (4) and ( 5), respectively, is shown in Table S32 (ESI †). In general, the observed cooperative effects in the here-investigated complexes are significantly smaller than those in the systems that we used for the introduction of this quantitative approach, 76 which may also be a reason for the failure in the theoretical description.…”

“…ref. 76), we analyze the shifts of the pre-band, since it is influenced by the coordinated metal ions. The orthogonal complexations yield the determination of the absorption (and emission) behavior of the homometallic species (1Au, 1Zn, 2Au 2 , and 2Zn) as well as the bimetallic species (1AuZn and 2Au 2 Zn).…”

“…74,75 In the paper presented here, we will analyze the cooperativity in heterometallic bi-and trinuclear gold/zinc complexes on the basis of their UV absorption and emission spectra by applying the approach we have already introduced for a series of palladium, platinum and iridium complexes. 76 2 Experimental section…”

Cooperative approaches in catalytic hydrogenation and dehydrogenation

“…The term cooperativity (and related terms such as synergism) is used to describe the enhanced effects obtained from the combination of multiple chemical entities. 12 This applies to a wide array of scenarios in the chemical literature. 12,13 For the purposes of this review, we will focus on a subset of cooperativity relevant to homogeneous catalysis.…”