Organobimetallic RuII–ReI 4-ethynylpyridyl complexes: structures and non-linear optical properties

Abstract

A series of heterobimetallic complexes, [RuCp(C[triple bond]Cpy-4)(P-P)][Re(CO)3(N-N)]+ (P-P = dppf, N-N = bpy 5, Me2bpy 6, tBu2bpy 7, phen 8, tpy 9; P-P = 2PPh3, N-N = bpy 10) have been obtained from Lewis addition between the metalloligands [RuCp(C[triple bond]Cpy-4)(P-P)] (P-P = dppf 1; 2PPh3 2) and solvent-stabilised fac-[Re(CH3CN)(CO)3(N-N)]+. All new complexes 5-10, together with fac-[ReBr(CO)3(tpy)] (3) and fac-[Re(CH3CN)(CO)3(tpy)][PF6] (4), are characterized by solution spectroscopy; 3 and 5-9 are also characterized by single-crystal X-ray crystallography. The terpyridine ligands in 3 and 9 are in an unusual 2-bidentate coordination mode with a pendant pyridyl. Electrochemical studies showed successive metal-based oxidations and a ligand-centered reduction in 5-10. Significant oxidation changes are observed at the Ru(II) and Re(I) centers in 5-10 when compared with their respective monometallic components. Cubic nonlinearities of 5-10 determined by the Z-scan technique at 750 nm reveal two-photon absorption that increases significantly on progression from Ru(II) monomeric precursors to heterobimetallics, suggesting NLO enhancement upon heterometallic complex formation.

Visible and Near‐IR Emissions from k2N‐ and k3N‐Terpyridine Rhenium(I) Assemblies Obtained by an [n×1] Head‐to‐Tail Bonding Strategy

“…Thus, in the case of complex 2 , two bands are predicted in close proximity at ν ≈1883–1891 cm −1 , whereas for complexes 5 and 6 a broad band at ν ≈1880–1900 cm −1 is calculated. The results for the k 2 N ‐species are in good agreement with those reported for other k 2 N ‐terpyridine fac ‐rhenium tricarbonyl species . The experimental infrared spectrum of the k 3 N ‐species features two strong stretching vibrations in the region ν ≈1800–1900 cm −1 , consistent with both the theoretical data and observations for previously studied rhenium dicarbonyl species …”

Group 8 metal alkynyl complexes for nonlinear optics

“…Dipolar complexes +The cubic NLO properties of small dipolar Group 8 metal alkynyl complexes had been assayed in the 1990s, values at a fixed wavelength of 800 nm typically being very low. More recent Z-scan studies at single wavelengths in the region 650-800 nm of alkynyl and alkenyl complexes 40 -45 (Figure 10)[14,32,[39][40][41], as well as degenerate four-wave mixing studies at 532 nm of the (poly)thiophene-5 bridged complexes 46 and 47(Figure 11)[42,43] have confirmed this general observation. The wellestablished dependence of the NLO response as a function of the π-bridge length was verified in these series of D-π-A complexes, with the metal center playing the role of the donor group, while barbiturate-terminated complexes were found to be less active than aldehyde-terminated analogues.…”

Optimised Syntheses of the Half-Sandwich Complexes FeCl(dppe)Cp*, FeCl(dppe)Cp, RuCl(dppe)Cp*, and RuCl(dppe)Cp

“…[20,21] The ligand substitution chemistry that has been developed on various half-sandwich complexes has led to their use as building blocks in supramolecular architectures [22][23][24][25] and surface supported nanoarchitectures, [26,27] and as frameworks for the investigation of non-linear optical properties. [28][29][30][31][32][33] The synthetic versatility is augmented by well-defined one-electron redox processes [34,35] which opens a range of further possibilities for use of these systems as platforms through which to generate and study mixed-valence complexes and electron-transfer phenomena. [36][37][38][39][40] The ability to systematically vary the nature of the metal and the steric and electronic properties of the half-sandwich fragment has allowed detailed investigation of the electronic and spectroscopic properties of such complexes.…”