Ruthenium Carbene and Allenylidene Complexes Supported by the Tertiary Amine−Aromatic Diimine Ligand Set: Structural, Spectroscopic, and Theoretical Studies

Abstract

Ruthenium-methoxycarbene and -allenylidene complexes bearing 1,4,7-trimethyl-1,4,7-triazacyclononane (Me 3 Tacn) and 1,10-phenanthroline (phen), [(Me 3 Tacn)(phen)RudC(OMe)R] 2+ (R ) CH 2 Ph (1), CHdCPh 2 (2), CHdC(C 6 H 4 Cl-4) 2 (3), CHdC(C 6 H 4 Me-4) 2 ( 4)), and [(Me 3 Tacn)(phen)Rud CdCdCR 2 ] 2+ (R ) Ph (5), C 6 H 4 OMe-4 (6)) have been prepared. The molecular structures of 1(PF 6 ) 2 and 2(PF 6 ) 2 reveal Ru-C distances of 1.917(3) and 1.906(4) Å, respectively. The lowest-energy dipoleallowed absorptions for complexes 1-4 (λ max ≈ 435 nm) are assigned as d π (Ru II ) f π*(phen) metalto-ligand charge transfer (MLCT) transitions, while those for complexes 5 and 6 (λ max ) 530 and 585 nm, respectively) are assigned as metal-perturbed π-π* [RudCdCdCR 2 ] intraligand transitions. Complexes 1-4 are emissive in glassy MeOH/EtOH at 77 K: excitation at λ ) 430 nm produces emission at λ max ) 570-620 nm, which are tentatively assigned as d π (Ru II ) f π*(phen) 3 MLCT in nature. Density functional theory (DFT) calculations, charge decomposition analysis (CDA), and natural bond orbital (NBO) analysis on complexes 1, 2, 5, and 6 suggest that allenylidene ligands are better electron donors and poorer acceptors compared with methoxycarbene ligands, and the Ru-C interactions in ruthenium-allenylidene and -methoxycarbene complexes can be depicted by the polarized formulation Ru δ+ dC δand nonpolarized formulation RudC, respectively. The methoxycarbene/allenylidene rotational barriers on 1, 2, and 5 are calculated to be 8.3, 6.3, and 1.5 kcal mol -1 , respectively.

A Ruthenium(II) Complex Supported by Trithiacyclononane and Aromatic Diimine Ligand as Luminescent Switch-On Probe for Biomolecule Detection and Protein Staining

“…Excitation of 1 ′ (31 μM) at 450 nm in acetonitrile resulted in an emission with λ max at 692 nm, a quantum yield of 2.334 × 10 −3 , and a lifetime of 0.272 μs. This emission was assigned as the triplet d π (Ru II ) → π*(N ∧ N) charge-transfer in nature based on comparison with analogous complexes reported previously 7 37 38 39 40 41 42 43 44 45 46 47 . The replacement of the bpy ligand with dcmb has been previously reported to red-shift the emission maximum of ruthenium(II) complexes 48 .…”

Carbon-Rich Ruthenium Allenylidene Complexes Bearing Heteroscorpionate Ligands

“…Further inspection of the spectra reveals a series of weak, broad transitions in the lower energy region between 700 and 1350 nm that can be attributed to HOMO → LUMO, HOMO-1 → LUMO, and HOMO-2 → LUMO excitations, which are MLCT transitions (Table ). The longest wavelength transitions in ruthenium allenylidene complexes have been assigned to MLCT transitions previously …”

Ruthenium complexes of 1,4,7-trimethyl-1,4,7-triazacyclononane for atom and group transfer reactions

“…a acac, pentane-2,4-dionate; biqn, 1,1 -biisoquinoline; bpy, 2,2 -bipyridine; cbpy*, (−)-3,3 -[(4S-trans)-1,3-dioxolane-4,5-dimethyl]-2,2 -bipyridine; diopy*, (R,R )-3,3 -(1,2-dimethylethylenedioxy)-2,2 -bipyridine; 3,3 -Me2bpy, 3,3 -dimethyl-2,2 -bipyridine; phen, 1,10-phenanthroline. b [20,40,41], -carbene/-vinylidene/-allenylidene [42,43], -nitrido [18,44], and -carbyne [19] complexes, is depicted in Table 1.…”