Trigonal‐Pyramidal Tetra‐Sandwich Complexes as 3D NLOphores

Abstract

Keywords: Second harmonic generation / Tetranuclear sandwich complexes / 3D NLOphores / X-ray structure determination / Redox properties / Iron / RutheniumThe Negishi cross-coupling reaction of 1,3,5-trihalobenzene with ferrocenyl-and ruthenocenyllithium, yields the corresponding 1,3,5-trimetallocenylated benzene derivatives in good yield, when 1,3,5-triiodobenzene is used. In a subsequent stacking reaction with the cationic (η 5 -cyclopentadienyl)ruthenium(II) and (η 5 -pentamethylcyclopentadienyl)ruthenium(II) half-sandwich complexes to the central benzene ring, the trigonal-pyramidal tetra-sandwich complexes (η 5 -cyclopentadienyl)(η 6 -1,3,5-triferrocenylbenzene)-ruthenium(II) hexafluorophosphate (4), (η 5 -pentamethylcyclopentadienyl)(η 6 -1,3,5-triferrocenylbenzene)ruthenium(II) hexafluorophosphate (5) and (η 5 -cyclopentadienyl)-(η 6 -1,3,5-triruthenocenylbenzene)ruthenium(II) hexafluorophosphate (6) are formed. X-ray structure analyses of the complexes 4 and 6 confirm the trigonal-pyramidal architecture composed of four sandwich units. Cyclic voltammetric studies of the ferrocenyl-containing complexes 4 and 5 reveal

The core of the matter – arene substitution determines the coordination and catalytic behaviour of tris(1-phosphanyl-1′-ferrocenylene)arene gold(i) complexes

“…36 As the groups of Lang and Santi have extensively shown, the nature of the arene core is decisive for the electrochemical response of the system both in terms of redox potentials and electronic communication, that is, the existence of mixedvalent oxidised states. [21][22][23][37][38][39][40][41][42][43][44][45][46][47][48][49] In our case, 1 : 1 ligand-tometal complexes of triazine derivative 1a (Chart 2, left) showed a distinct delocalised coinage metal-π(C 3 N 3 ) interaction, 50 while 1 : 3 ligand-to-gold complexes of 1a-c (Chart 2, right) demonstrated how the electron density of the respective core determined the electrochemical response both with respect to redox potential and reversibility. Furthermore, the arene cores were also found to impact the catalytic activity of these trinuclear gold(I) complexes in the ring-closing isomerisation of N-(2-propyn-1-yl)benzamide (2) to 5-methylene-2-phenyl-4,5dihydrooxazole (3a).…”

Extended Threefold‐Symmetric Second‐Harmonic‐Generation Chromophores Based on 1,3,5‐Trisubstituted Benzene Complexes

“…During our work on the influence of the silyl protecting groups on the coordination of a CpRu + unit and its resulting NLO effect, we were simultaneously interested in the elongation of the π system of our established NLOphores5 and the search for further synthetic strategies to synthesize the potential 3D NLOphore (η 5 ‐cyclopentadienyl)[1,3,5‐tris(ferrocenylethynyl)‐η 6 ‐benzene]ruthenium(II) hexafluorophosphate (Scheme , R = ferrocenyl) 6. This overlap of synthetic aims motivated us to explore the influence of the dicobalt hexacarbonyl function as a protecting group.…”

“…Within our group, we have designed the so‐called “(2+1) 3D NLOphores” made up of a 1,3,5‐donor‐substituted benzene ring (2D chromophore) and a perpendicularly coordinated CpRu + (Cp = cyclopentadienyl) unit with an electron‐withdrawing function (1D). The recently reported 1,3,5‐trismetallocenyl‐substituted benzene complexes (Figure 1, A) display threefold symmetry and demonstrate a small but distinct SHG 5. The small SHG effect is due to the rather short conjugation length L .…”

“… Archetypical threefold‐symmetric 1,3,5‐trismetallocenyl‐substituted cationic benzene complexes A5 and B 6…”

Negishi coupling in the synthesis of advanced electronic, optical, electrochemical, and magnetic materials

“…73 When 1,3,5-tribromobenzene was used, the yields were much lower, being 35% and 13% for 60 and 61, respectively. Organic optical materials that are important to organic electronic and optoelectronic devices include but are not limited to nonlinear optical (NLO) materials, liquid crystals, light emitters, and light harvesting materials.…”