Redox behavior of aromatic tridentate imine ligand complexes of manganese and chromium

RAO, J. M.; Hughes, Michael C.; Macero, Daniel J.

doi:10.1016/s0020-1693(00)95591-9

Cited by 25 publications

(11 citation statements)

References 5 publications

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“…Complexes 1−3 have been synthesized previously, but their photophysical properties have not been fully characterized; 4−6 are novel complexes. 15,48,56 Purification of these complexes is achieved via column chromatography in the case of 1, column chromatography followed by recrystallization from an acetonitrile−ether solution in the case of 3, and recrystallization from acetonitrile−ether solutions in the cases of 2 and 4−6. The low yields (<40%) for these compounds can be attributed in part to the extensive purification required to obtain samples that are sufficiently pure for emission spectroscopy.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Compared to Cr(III) tris-bipyridyl complexes, the electrochemical and photophysical properties of Cr(III) bis-terpyridyl complexes have received little attention. ,,,− Many of those reports are aimed at understanding the relatively short (<200 ns) excited-state lifetimes of this family of complexes. Nonetheless, Cr(III) terpyridyl complexes present opportunities to address the challenges posed by the poor photostability and weak visible absorption of Cr(III) tris-bipyridyls.…”

Section: Introductionmentioning

confidence: 99%

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Chromium(III) Bis-Arylterpyridyl Complexes with Enhanced Visible Absorption via Incorporation of Intraligand Charge-Transfer Transitions

et al. 2017

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A series of chromium(III) bis-arylterpyridyl complexes containing intraligand charge-transfer (ILCT) excited states were prepared and characterized. These complexes show significant absorption in the visible region due to the ILCT bands. The ILCT bands are tunable across the UV and visible spectrum via incorporation of electron-withdrawing and electron-donating groups on the aryl ring. The absorption of Cr(4'-(4-methoxyphenyl)-2,2':6',2″-terpyridine) (4) in particular is much stronger in the visible region (ε = 11 900 M cm at 450 nm and ε = 5090 M cm at 500 nm) than that of the parent complex Cr(tpy) (tpy = 2,2':6',2″-terpyridine; ε = 2160 M cm at 450 nm, and ε = 170 M cm at 500 nm). Emission experiments on this series reveal Cr(III)-based phosphorescence with lifetimes from 140 to 600 ns upon excitation into the ILCT bands, which indicates funneling of the excitation energy from ligand-localized excited states to Cr(III)-based excited states. Cyclic voltammograms exhibit at least three reversible ligand-based reductions. The first reduction shows shifts of up to -160 mV compared to Cr(tpy). The excited-state reduction potential of these complexes ranges from +0.95 to +1.04 V vs the ferrocene/ferrocenium couple, making them potent photooxidants.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Chromium(III) Bis-Arylterpyridyl Complexes with Enhanced Visible Absorption via Incorporation of Intraligand Charge-Transfer Transitions

et al. 2017

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“…Neither homo-nor heteroleptic complexes of manganese and ddpd have been reported so far. In contrast, colourless complexes of the type [Mn(tpy) 2 ] 2+ are easily formed from MnCl 2 ×4H 2 O, tpy and counter ion exchange, for example by perchlorate [87]. The manganese(II) complex cation features a high-spin d 5 electron configuration (S = 5 /2) with χT = 4.62 cm 3 K mol −1 at room temperature (Table 5) [87].…”

Section: [Mn(ddpd) 2 ] N+mentioning

confidence: 99%

“…In contrast, colourless complexes of the type [Mn(tpy) 2 ] 2+ are easily formed from MnCl 2 ×4H 2 O, tpy and counter ion exchange, for example by perchlorate [87]. The manganese(II) complex cation features a high-spin d 5 electron configuration (S = 5 /2) with χT = 4.62 cm 3 K mol −1 at room temperature (Table 5) [87]. Expectedly, ligand field transitions are Laporte and spin-forbidden and only π-π* transitions appear at 284, 323 and 335 nm in CH 3 CN [123].…”

Section: [Mn(ddpd) 2 ] N+mentioning

confidence: 99%

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Ddpd as Expanded Terpyridine: Dramatic Effects of Symmetry and Electronic Properties in First Row Transition Metal Complexes

et al. 2018

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The 2,2′:6′:2″-terpyridine ligand has literally shaped the coordination chemistry of transition metal complexes in a plethora of fields. Expansion of the ligand bite by amine functionalities between the pyridine units in the tridentate N,N’-dimethyl-N,N’-dipyridine-2-yl-pyridine-2,6-diamine ligand (ddpd) modifies the properties of corresponding transition metal complexes, comprising redox chemistry, molecular dynamics, magnetism and luminescence. The origins of these differences between ddpd and tpy complexes will be elucidated and comprehensively summarized with respect to first row transition metal complexes with d2–d10 electron configurations. Emerging applications of these ddpd complexes complementary to those of the well-known terpyridine ligand will be highlighted.

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Nickel‐Catalyzed Reductive Alkylation of Heteroaryl Imines**

2022

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A Ni-catalyzed reductive cross-coupling of heteroaryl imines with C(sp 3 ) electrophiles for the preparation of heterobenzylic amines is reported. This umpolung-type alkylation proceeds under mild conditions, avoids the pre-generation of organometallic reagents, and exhibits good functional group tolerance. Mechanistic studies are consistent with the imine substrate acting as a redox-active ligand upon coordination to a low-valent nickel center. The resulting Ni-bis(2-imino)heterocycle complexes can engage in alkylation reactions with a variety of C(sp 3 ) electrophiles, giving the heterobenzylic amine products in good yields.

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Redox behavior of aromatic tridentate imine ligand complexes of manganese and chromium

Cited by 25 publications

References 5 publications

Chromium(III) Bis-Arylterpyridyl Complexes with Enhanced Visible Absorption via Incorporation of Intraligand Charge-Transfer Transitions

Chromium(III) Bis-Arylterpyridyl Complexes with Enhanced Visible Absorption via Incorporation of Intraligand Charge-Transfer Transitions

Ddpd as Expanded Terpyridine: Dramatic Effects of Symmetry and Electronic Properties in First Row Transition Metal Complexes

Nickel‐Catalyzed Reductive Alkylation of Heteroaryl Imines**

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