NIR‐Emissive Chromium(0), Molybdenum(0), and Tungsten(0) Complexes in the Solid State at Room Temperature

Abstract

The development of NIR emitters based on earthabundant elements is an important goal in contemporary science. We present here Cr(0), Mo(0), and W(0) carbonyl complexes with a pyridyl-mesoionic carbene (MIC) based ligand. A detailed photophysical investigation shows that all the complexes exhibit dual emissions in the VIS and in the NIR region. The emissive excited states are assigned to two distinct triplet states by time-resolved emission and step-scan FTIR spectroscopy at variable temperature, supported by density functional theory. In particular, the NIR emissive triplet state exhibits unprecedented lifetimes of up to 600 � 10 ns and quantum yields reaching 1.7 • 10 À 4 at room temperature. These are the first examples of Cr(0), Mo(0) and W(0) complexes that emit in the NIR II region.

Chemistry of Compounds Based on 1,2,3-Triazolylidene-Type Mesoionic Carbenes

“… 97 More recently, the same groups have shown that the aforementioned Cr(0) and Mo(0) and the analogous W(0) complexes are dual emitters in the solid state at room temperatures. 153 These complexes emit in the visible as well as in the NIR II region. The quantum yield, particularly for the W(0) complex, is remarkably high.…”

Matrix Effects on Photoluminescence and Oxygen Sensitivity of a Molecular Ruby

“…platinum, ruthenium, iridium, or lanthanide ions [5] . Over the past years, growing efforts have been dedicated to develop and exploit new types of photoactive metal complexes based on earth‐abundant metals, such as copper, [6] zirconium, [7] iron, [8] molybdenum, [9] manganese, [10] cobalt, [11] and chromium, [9d,12] which are considered as promising candidates for eco‐friendly luminescence and photocatalysis applications [13]…”

Pincer‐Type Mesoionic Carbene Nickel(II) Complexes: Synthesis, Properties, Reactions, and Catalytic Application to the Suzuki–Miyaura Coupling Reaction of Aryl Bromides

“…Mesoionic carbenes (MICs) have recently attracted a lot of attention in the field of transition‐metal catalysis for organic transformations [1–9] and photophysical materials [10–16] . In particular, 1,2,3‐triazol‐5‐ylidene (triazolylidene) is the most attractive ligand motif and has been well established because it can be easily synthesized via the [3+2] Huisgen reaction between alkynes and azides [17–18] .…”

“…Mesoionic carbenes (MICs) have recently attracted a lot of attention in the field of transition-metal catalysis for organic transformations [1][2][3][4][5][6][7][8][9] and photophysical materials. [10][11][12][13][14][15][16] In particular, 1,2,3-triazol-5-ylidene (triazolylidene) is the most attractive ligand motif and has been well established because it can be easily synthesized via the [3 + 2] Huisgen reaction between alkynes and azides. [17][18] Although several reports have been published on the palladium chemistry of MIC complexes, [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] examples of MICs bound to nickel centers are rare, as shown in Figure 1.…”

“…Moreover, copper complexes have been reported for catalytic applications toward the reduction of unsaturated molecules [53] . Among several methods used to prepare late‐transition metal MIC complexes, the most accessible and common protocol is the use of their silver MIC analogues as intermediates [15–34,54−55] . However, the silver method has not been applied to previously reported nickel MIC complexes, [35–40] although the similar nickel imidazolylidene complexes can be made by the silver method [56–57] …”