VI Contents 1.4.2.1 Energetics of the Reactions 28 14211 Natural Processes 28 1.4.2.1.2 Artificial Processes 29 1.4.2.1.3 Photoelectrochemical Reduction 33 1.5 Conclusions 34 Refere ces 2 Nitrogen Monoxide us Oxide Bindi ing and Reduction 4 Kenneth D.Karlin 2 Introduction 22 NO 44 2.2.1 Bonding and structures of metal Nitrosyls 44 2.2.1.1 Heme Proteins:Guanylate Cyclase-NO Binding and Trans-bond labilization 47 2.2.12 Bridging (nu)Complexes 49 2213 n-uNO Bridg ing Complexes 49 2)14 n.NO Bridging Complexes 50 2.2.1.5 Isonitrosyl and Side-onNO Comple xes 50 2.2.1.6 Side-on NO Coppe t Protein Structu res 51 2.2.1.7 of Nitr Metal Co of No mplexes 53 nd Related Che mistry Chemical Reduction of Metal und NO 21 I-NO Redu ction Ac NoN-O Cleavage 56 Electrophilic ttac HNO (Nitroxyl) Complexes 58 2.2.2.3 Electrocatalytic Reduction of NO 2.2.2.4 Biological NO Reduction:NORs 61 2.2.2.4.1 Bacterial NORs of the Heme Copper Oxidase(HCO)Type 61 2.2.2.4.2 Models for NORs 63 2.2.2.4.3 Fungal P450-type NORs 63 2.2.2.4.4 Flavorubredoxins as Scavenging(S)-NORs 64 2225 Metal Complex-mediated NO Disproportionation 65 23 N,066 2.3.1 Structure and Bonding 66 2.3.2 Metal- 68 sfer Re n 6 fe avage 70 Ele taly luction of N2O to N2 71 Biological N2O Reduction 4 Summary and Conclusions References 1.4.2.1 Energetics of the Reactions 28 1.4.2.1.1 Natural Processes 28 1.4.2.1.2 Artificial Processes 29 1.4.2.1.3 Photoelectrochemical Reduction 33 1.5 Conclusions 34 References 35 2 Nitrogen Monoxide and Nitrous Oxide Binding and Reduction 43 Dong-Heon Lee, Biplab Mondal, and Kenneth D. Karlin 2.1 Introduction 43 2.2 NO 44 2.2.1 Bonding and Structures of Metal Nitrosyls 44 2.2.1.1 Heme Proteins: Guanylate Cyclase – NO Binding and Trans-bond Labilization 47 2.2.1.2 Bridging (
1 -2-) Complexes 49 2.2.1.3
1 -3-NO Bridging Complexes 49 2.2.1.4
2 -NO Bridging Complexes 50 2.2.1.5 Isonitrosyl and Side-on
2 -NO Complexes 50 2.2.1.6 Side-on
2 -NO Copper Protein Structures 51 2.2.1.7 Spectroscopic Features of Nitrosyl Metal Complexes 53 2.2.2 Chemical Reduction of NO and Related Chemistry 53 2.2.2.1 Chemical Reduction of Metal-bound NO 53 2.2.2.1.1 Metal–NO Reduction Accompanied by N–O Cleavage 56 2.2.2.2 Electrophilic Attack on Metal-bound NO :HNO (Nitroxyl) Complexes 58 2.2.2.3 Electrocatalytic Reduction of NO 60 2.2.2.4 Biological NO Reduction: NORs 61 2.2.2.4.1 Bacterial NORs of the Heme Copper Oxidase (HCO) Type 61 2.2.2.4.2 Models for NORs 63 2.2.2.4.3 Fungal P450-type NORs 63 2.2.2.4.4 Flavorubredoxins as Scavenging (S)-NORs 64 2.2.2.5 Metal Complex-mediated NO Disproportionation 65 2.3 N2O 66 2.3.1 Structure and Bonding 66 2.3.2 Metal-mediated N2O Reduction 68 2.3.2.1 Oxo Transfer Reactions 68 2.3.2.2 Catalytic Oxo Transfer 70 2.3.2.3 N2O N–N Bond Cleavage 70 2.3.2.4 Electrocatalytic Reduction of N2O to N2 71 2.3.2.5 Biological N2O Reduction 72 2.4 Summary and Conclusions 73 References 74 VI Contents