Photoredox behavior of coordination complexes of nd6 metals.  Contrasting redox modes in azidopentacyanocobaltate(III) and azidopentaamminerhodium(III)

Ferraudi, G.; Endicott, John F.

doi:10.1021/ja00788a049

Cited by 18 publications

(7 citation statements)

References 2 publications

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“…The bound structure is best described as a resonance hybrid, Fig. These metal azides have been found to undergo a variety of different photoreactions, which include: (i) photosubstitution of the azide ligand [45,46], (ii) photoreduction of an oxidising metal [30,31,33,[47][48][49][50][51][52][53][54] (iii) the generation of metalnitrenes [55][56][57][58][59][60][61] and (iv) production of singlet oxygen [62,63]. It has been stated that almost any transition metal azide complex is light sensitive, regardless of oxidation state [31].…”

Section: Diazido-pt(iv) Complexesmentioning

confidence: 99%

Photoactivatable Platinum Complexes

Bednarski

Mackay²,

Sadler³

2007

ACAMC

224

217

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The development of photoactivatable prodrugs of platinum-based antitumor agents is aimed at increasing the selectivity and hence lowering toxicity of this important class of antitumor drugs. These drugs could find use in treating localized tumors accessible to laser-based fiber-optic devices. Pt(IV) complexes appeared attractive because these octahedral complexes are usually substitution inert and require reduction to the Pt(II) species to become cytotoxic. Based on the knowledge of Pt(IV) photochemistry, Pt(IV) analogs of cisplatin, [Pt(en)Cl(2)] and transplatin were designed, synthesized and investigated for their ability to be photoreduced to cytotoxic Pt(II) species. Two classes of photoactivatable Pt complexes have been looked at thus far: diiodo-Pt(IV) and diazido-Pt(IV) diam(m)ine complexes. The first generation, diiodo-Pt(IV) complexes, represented by cis, trans-[Pt(en)(I)(2)(OAc)(2)], react to visible light by binding irreversibly to DNA and forming adducts with 5'-GMP in the same manner as [Pt(en)Cl(2)]. Furthermore, the photolysis products are cytotoxic to human cancer cells in vitro. However, these complexes are too reactive towards biological thiols (i.e., glutathione), which rapidly reduced them to cytotoxic Pt(II) species, thus making them unsuitable as drugs. The second generation, diazido-Pt(IV) complexes, represented by cis, trans, cis-[Pt(N(3))(2)(OH)(2)(NH(3))(2)] and cis, trans-[Pt(en)(N(3))(2)(OH)(2)], are also photosensitive, binding irreversibly to DNA and forming similar products with DNA and 5'-GMP in the presence of light as the respective Pt(II) complexes. However, they are stable to glutathione and thus show very low dark cytotoxicity. Light of lambda(irr) = 366 nm activates both complexes to cytotoxic species that effectively kill cancer cells by destroying their nuclei, leaving behind shrunken cell ghosts. Interestingly, the all-trans analog, trans, trans, trans-[Pt(N(3))(2)(OH)(2)(NH(3))(2)] is non-toxic to HaCaT keratinocytes in the dark, but as active as cisplatin in the light. These studies show that photoactivatable Pt(IV) antitumor agents represent a promising area for new drug development.

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Section: Diazido-pt(iv) Complexesmentioning

confidence: 99%

Photoactivatable Platinum Complexes

Bednarski

Mackay²,

Sadler³

2007

ACAMC

224

217

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“…Attempts to synthesize nitrido complexes of the later metals have been reported to result in the formation of proposed metal-nitrene (M=NH) species. [16][17][18][19][20][21][22][23][24][25][26] Bona fide examples of imido complexes are also rare for metals to the right of group 8; incidentally, a related phenomenon involving metal-oxo compounds has led to the division between groups 8 and 9 being colloquially dubbed ''the oxo wall.'' Though few well characterized examples are known, metal imido species beyond the oxo wall are often invoked as transient highly reactive intermediates in late metal-catalyzed nitrene transfer chemistry.…”

Section: Introductionmentioning

confidence: 99%

Terminal Nitrido and Imido Complexes of the Late Transition Metals

Berry

2009

Comments on Inorganic Chemistry

277

232

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Compounds that contain a late transition metal-nitrogen multiple bond represent important reactive intermediate species in many useful organic and inorganic transformations. In order to understand the role that these intermediates play in reactions, it is important to have a full understanding of their electronic structure. This paper reviews the known structural motifs that occur in late transition metal nitrido and imido compounds, and provides a correlation between geometric structure and electronic structure. Also, intermediate species that have been postulated but not yet isolated are discussed, as these compounds represent exciting targets for further efforts in synthetic inorganic chemistry.

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“…18 By excitation into the LMCT band the quantum yield of the photoredox reaction is about 1 order of magnitude higher than that obtained by excitation into the LF band. [17][18][19][20] In spite of this difference and because of the azide radical formation, a powerful oxidizing agent (E°ϭ ϩ1.34 V), 21 the initiation of the polymerization reaction by excitation at long [Co(NH 3 ) 5 N 3 ] 2ϩ wavelength is conceivable. In a recent article we gave evidence that azidopentaammine cobalt(III) complex can efficiently initiate the polymerization reaction of 2-hydroxyethylmethacrylate upon excitation at 365 and 546 nm.…”

Section: Introductionmentioning

confidence: 99%