Isolable Stannenolates Enable the Synthesis of Visible‐Light Photoinitiators

Abstract

Dedicated to Professor Frank Uhlig on the occasion of his 60 th birthdayIsolable stannenolates LKSn[(CO)R] 3 (R = 2,4,6-trimethylphenyl (1 a, b), L = DME for (1 a) or 18-crown-6 for (1 b)), a new building block for the synthesis of effective Sn-based photoinitiators, were synthesized. The formation of these derivatives was confirmed by NMR spectroscopy, UV/Vis spectroscopy as well as X-ray crystallographic analysis. Compound 1 a is employed as a synthon in main group chemistry through reactions with two different types of electrophiles (acid chlorides and alkyl halides). All investigated electrophiles react via the salt metathesis reaction and gave rise to novel acylstannanes in good to excellent yields. The applicability as visible light photoinitiators is demonstrated by photobleaching (UV/Vis absorption spectroscopic studies) as well as through application in photo-DSC studies.

Recent Advances in Type I Photoinitiators for Visible Light Induced Photopolymerization

“…presented a reaction pathway and a variety of Sn‐based PIs (Figure 21), similar to their germanium equivalents. These PIs show an even more pronounced red‐shift with absorption up to 600 nm and reasonable photoinitiating capacity [67] …”

“…These PIs show an even more pronounced red-shift with absorption up to 600 nm and reasonable photoinitiating capacity. [67] Further research on tin compounds would be interesting for the future. However, storage stability is a main topic for stannanes and might constitute their limit for commercial application.…”

“…A variety of acylstannanes for photoinitiation. [67] Figure 22. Structure of 2-(4-methoxystyryl)-4,6-bis(trichloromethyl)-1,3,5triazine (R-Cl), [10] a radical PI producing chloride radicals, and a coumarin based initiator (DCCA).…”

Synthesis and Characterization of New Counterion-Substituted Triacylgermenolates and Investigation of Selected Metal–Metal Exchange Reactions

“…However, only uncharacterizable polymers were found. 16 The same holds true for tetraacylgermanes. At the beginning of the reaction, the reaction solution changed from yellow to orange, which indicates the formation of the target compound.…”

“…Recently, we have investigated the usage of elemental lithium to induce electron-transfer reactions with tetraacylstannanes. However, only uncharacterizable polymers were found . The same holds true for tetraacylgermanes.…”