Photophysical studies of trans-bis(phenylethynyldiisopropylamidinato)bis(acetato)dimetal complexes involving MM quadruple bonds where M = Mo or W.
The title compounds trans-M(2)(O(2)CMe)(2)[C((i)PrN)(2)C≡C-Ph](2), I (M = Mo) and II (M = W), show electronic absorptions in the visible region of the spectrum assignable to (1)MLCT [M(2)δ to phenylethynylamidinate π*]. These compounds show dual emission from S(1) and T(1) states. For both I and II, S(1) is (1)MLCT, but for I the T(1) state is shown to be MMδδ* while for II T(1) is (3)MLCT. The lifetimes of the S(1) and T(1) states have been determined by femtosecond and nanosecond transient absorption spectroscopy: for I S(1) ∼ 20 ps and T(1) ∼ 100 μs and for II S(1) ∼ 6 ps and T(1) ∼ 5 μs. From solvent dependence of the absorption and emission spectra, we suggest that the S(1) states are localized on one amidinate ligand though the initial absorption is to a delocalized state.
Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210-1185, United States.
Brian G
BG
Alberding
Malcolm H
MH
Chisholm
Terry L
TL
Gustafson
Yao
Y
Liu
Carly R
CR
Reed
Claudia
C
Turro
D000480:Alkynes / Q000737:chemistry; D000578:Amidines / Q000737:chemistry; D008958:Models, Molecular; D008982:Molybdenum / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D010777:Photochemistry; D011789:Quantum Theory; D014414:Tungsten / Q000737:chemistry*
D000480:Alkynes; D000578:Amidines; D009942:Organometallic Compounds; D008982:Molybdenum; D014414:Tungsten