Aerobic Oxidation of an Osmium(III) N-Hydroxyguanidine Complex To Give Nitric Oxide

Jing Xiang; Qian Wang; Shek Man Yiu; Wai Lun Man; Hoi Ki Kwong; Tai Chu Lau

doi:10.1021/acs.inorgchem.6b00652

Aerobic Oxidation of an Osmium(III) N-Hydroxyguanidine Complex To Give Nitric Oxide

Jing Xiang, Qian Wang, Shek Man Yiu, Wai Lun Man, Hoi Ki Kwong, Tai Chu Lau^*

^*Corresponding author for this work

Department of Chemistry

Research output: Contribution to journal › Journal article › peer-review

14 Citations (Scopus)

Abstract

The aerobic oxidation of the N-hydroxyguanidinum moiety of N-hydroxyarginine to NO is a key step in the biosynthesis of NO by the enzyme nitric oxide synthase (NOS). So far, there is no chemical system that can efficiently carry out similar aerobic oxidation to give NO. We report here the synthesis and X-ray crystal structure of an osmium(III) N-hydroxyguanidine complex, mer-[OsIII{NH═C(NH₂)(NHOH)}(L)(CN)₃]− (OsGOH, HL = 2-(2-hydroxyphenyl)benzoxazole), which to the best of our knowledge is the first example of a transition metal N-hydroxyguanidine complex. More significantly, this complex readily undergoes aerobic oxidation at ambient conditions to generate NO. The oxidation is pH-dependent; at pH 6.8, fac-[Os(NO)(L)(CN)₃]− is formed in which the NO produced is bound to the osmium center. On the other hand, at pH 12, aerobic oxidation of OsGOH results in the formation of the ureato complex [OsIII(NHCONH₂)(L)(CN)₃]^2–and free NO. Mechanisms for this aerobic oxidation at different pH values are proposed.

Original language	English
Pages (from-to)	5056–5061
Number of pages	6
Journal	Inorganic Chemistry
Volume	55
Issue number	10
DOIs	https://doi.org/10.1021/acs.inorgchem.6b00652
Publication status	Published - 16 May 2016

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title = "Aerobic Oxidation of an Osmium(III) N-Hydroxyguanidine Complex To Give Nitric Oxide",

abstract = "The aerobic oxidation of the N-hydroxyguanidinum moiety of N-hydroxyarginine to NO is a key step in the biosynthesis of NO by the enzyme nitric oxide synthase (NOS). So far, there is no chemical system that can efficiently carry out similar aerobic oxidation to give NO. We report here the synthesis and X-ray crystal structure of an osmium(III) N-hydroxyguanidine complex, mer-[OsIII{NH═C(NH2)(NHOH)}(L)(CN)3]− (OsGOH, HL = 2-(2-hydroxyphenyl)benzoxazole), which to the best of our knowledge is the first example of a transition metal N-hydroxyguanidine complex. More significantly, this complex readily undergoes aerobic oxidation at ambient conditions to generate NO. The oxidation is pH-dependent; at pH 6.8, fac-[Os(NO)(L)(CN)3]− is formed in which the NO produced is bound to the osmium center. On the other hand, at pH 12, aerobic oxidation of OsGOH results in the formation of the ureato complex [OsIII(NHCONH2)(L)(CN)3]2– and free NO. Mechanisms for this aerobic oxidation at different pH values are proposed.",

author = "Jing Xiang and Qian Wang and Yiu, {Shek Man} and Man, {Wai Lun} and Kwong, {Hoi Ki} and Lau, {Tai Chu}",

note = "Funding information: This work was supported by a GRF grant (CityU 101811), the Hong Kong University Grants Committee Area of Excellence Scheme (AoE/P-03-08), and the Natural Science Foundation of China (21201023). Publisher copyright: {\textcopyright} 2016 American Chemical Society",

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T1 - Aerobic Oxidation of an Osmium(III) N-Hydroxyguanidine Complex To Give Nitric Oxide

AU - Xiang, Jing

AU - Wang, Qian

AU - Yiu, Shek Man

AU - Man, Wai Lun

AU - Kwong, Hoi Ki

AU - Lau, Tai Chu

N1 - Funding information: This work was supported by a GRF grant (CityU 101811), the Hong Kong University Grants Committee Area of Excellence Scheme (AoE/P-03-08), and the Natural Science Foundation of China (21201023). Publisher copyright: © 2016 American Chemical Society

PY - 2016/5/16

Y1 - 2016/5/16

N2 - The aerobic oxidation of the N-hydroxyguanidinum moiety of N-hydroxyarginine to NO is a key step in the biosynthesis of NO by the enzyme nitric oxide synthase (NOS). So far, there is no chemical system that can efficiently carry out similar aerobic oxidation to give NO. We report here the synthesis and X-ray crystal structure of an osmium(III) N-hydroxyguanidine complex, mer-[OsIII{NH═C(NH2)(NHOH)}(L)(CN)3]− (OsGOH, HL = 2-(2-hydroxyphenyl)benzoxazole), which to the best of our knowledge is the first example of a transition metal N-hydroxyguanidine complex. More significantly, this complex readily undergoes aerobic oxidation at ambient conditions to generate NO. The oxidation is pH-dependent; at pH 6.8, fac-[Os(NO)(L)(CN)3]− is formed in which the NO produced is bound to the osmium center. On the other hand, at pH 12, aerobic oxidation of OsGOH results in the formation of the ureato complex [OsIII(NHCONH2)(L)(CN)3]2– and free NO. Mechanisms for this aerobic oxidation at different pH values are proposed.

AB - The aerobic oxidation of the N-hydroxyguanidinum moiety of N-hydroxyarginine to NO is a key step in the biosynthesis of NO by the enzyme nitric oxide synthase (NOS). So far, there is no chemical system that can efficiently carry out similar aerobic oxidation to give NO. We report here the synthesis and X-ray crystal structure of an osmium(III) N-hydroxyguanidine complex, mer-[OsIII{NH═C(NH2)(NHOH)}(L)(CN)3]− (OsGOH, HL = 2-(2-hydroxyphenyl)benzoxazole), which to the best of our knowledge is the first example of a transition metal N-hydroxyguanidine complex. More significantly, this complex readily undergoes aerobic oxidation at ambient conditions to generate NO. The oxidation is pH-dependent; at pH 6.8, fac-[Os(NO)(L)(CN)3]− is formed in which the NO produced is bound to the osmium center. On the other hand, at pH 12, aerobic oxidation of OsGOH results in the formation of the ureato complex [OsIII(NHCONH2)(L)(CN)3]2– and free NO. Mechanisms for this aerobic oxidation at different pH values are proposed.

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ER -

Aerobic Oxidation of an Osmium(III) N-Hydroxyguanidine Complex To Give Nitric Oxide

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