71-18,098 TOKEL, Nurhan E lias, 1942- ELECTROCHEMICAL INVESTIGATION OF TRANSITION METAL COMPLEXES OF QUADRIDENTATE MACROCYCLIC LIGANDS. The Ohio State University, Ph.D., 1970 Chemistry, inorganic University Microfilms, A XEROX Company, Ann Arbor, Michigan THIS DISSERTATION HAS BEEN MICROFILMED EXACTLY AS RECEIVED ELECTROCHEMICAL INVESTIGATION OF TRANSITION METAL COMPLEXES OF QUADRIDENTATE MACROCYCLIC LIGANDS DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Nurhan Elias Tokel, B.S. The Ohio State University 1970 Approved by A d v iser Department of Chemistry A CKNOW LEDGMENTS The author wishes to express his most sincere thanks and gratitude to Professor Daryle H. Busch and Professor Larry B, Anderson for their encouragement, helpful advice and ocean-wide patience during this research. Helpful discussions with fellow graduate students and postdoctoral fellows, particularly, Dr. V. Katovic, Dr. F. V. Lovecchio, and S. Betso are gratefully ac­ knowledged. The Graduate Fellowships granted by the Phillips Petroleum and Chrysler Corporations are acknowledged. I would like to express my warmest thanks to my parents, Mrs. Henry F. Brodish, and the other persons whose understanding and support helped me to complete this work. I gratefully appreciate the enthusiasm shown by my wife, Constance, for this work and her sleepless hours for the prepara­ tion of the drawings necessary for the dissertation. VITA March 9, 1942 ................................................................... Born--Istanbul, Turkey 1966 ..............................................................................................B. S. in Chemistry, Robert College, Istan­ bul, Turkey 1966-1967 .................................................................................Teaching Assistant, The Ohio State Univer­ sity, Columbus, Ohio 1967-196 8 .................................................................................Research Assistant, The Ohio State Univer­ sity, Columbus, Ohio 1968-196 9 .................................................................................Phillips Petroleum Fellow, The Ohio State U n iv ersity 1969-1970 .................................................................................Chrysler Corporation Fellow, The Ohio State U n iv ersity 1970 ..............................................................................................Postdoctoral Research, The University of Texas, Austin, Texas PUBLICATIONS 11 Mutual Ligand-Metal Ion Oxidation State Stabilization in a System Containing a Quadridentate Macrocycle Analogous to the P or­ phyrin Ring, n N. E. Tokel, V. Katovic, K. Farmery, L. B. Anderson, and D. H. Busch, J. Am. Chem. Soc., 9£, 400 (1970). "Spectral and Electrochemical Studies of the Copper(Il) Complexes of Two Macrocyclic Ligands," L. F. Lindoy, N. E. Tokel, L. B. Anderson, and D, H. Busch, submitted for publication. FIELDS OF STUDY Major Field: Inorganic Chemistry Studies in the Electrochemical Properties of Macrocyclic C o m p lexes. TABLE OF CONTENTS Page ACKNOWLEDGMENTS...................................................................................... ii VITA .................................................................................................................................. iii LIST OF TABLES ............................................................................................. x ii LIST OF FIGURES ........................................................................................ xv LIST OF SCHEMES ......................................................................................... xv iii INTRODUCTION .......................................................................................... 1 Vitamin B12 and Vitamin Bw Coenzyme . .......................... 1 A. General Background on Vitamin B jj and Vitamin B^ Coenzyme ........................................... 1 B. Valence State of the Cobalt Atom in Vitamin Bj 2 and the Coenzyme ........................................................ 7 C. Electrochemical Studies on Vatamin B^ and its Reduced Form s ............................................................ 9 1. Vitamin B^ (Cyanocobalamin) .................. 9 2. Vitamin B^a (Hydroxo-cobalamin) .... I I 3. V itamin B ur ......................................................... 12 4. Vitamin Bjzs ......................................................... 16 D. N a tu re of V itam in B j 2 S ................................................ 18 E. Important Biochemical Reactions of Vitamin Bji C oenzym e .............................................. 24 v Page 1. Enzymic Reactions Requiring Vitamin B«................................................................................... 25 X. 1 Methylation of Homocysteine. 25 1.2 Methane Formation .................................. 27 1.3 Acetate Synthesis from Carbon D ioxide ......................................................... 30 2. Enzymic Reactions Requiring 5'-deoxy- adenosyl Corrinoide ........................................ 32 2. 1 Glutamate Mutase Reaction .......... 32 2.2 Methylrnalonyl-CoA Mutase Reaction. 33 2. 3 Diol Dehydratase Reaction .......................... 33 2.4 Glycerol Dehydratase Reaction .... 34 2.5 Ethanolamine Deaminase Reaction . 35 2. 6 Ribonucleoside Triphosphate Red- d u c ta s e .................................................................... 36 2,7 P-lysine Mutase Reaction ........................... 37 F. Chemical Synthesis of the Bl2 Coenzyme and its Derivatives ................................................... 40 G, Chemical Reactions of Vitamin Bl2 Coenzyme and its Derivatives .................................................... 43 1. Corrin Nucleus .............................. 43 1. 1 Reaction with Acids and Halogens. 43 2. Carbon-Cobalt Bond ..................................................... 45 2. 1 Reaction with Acids ....................................... 45 vi Page 2. 2 Decomposition by Alkaline Cyanide.. 47 2.3 Homolytic Cleavage by Light ................. 49 H. Electrochemical Work on Vitamin Bl2 Coenzyme and its Organocobalt Derivatives ................. 53 I . Vitamin B12 Coenzyme Model Compounds. 60 1. Nucleophilic Substitution Mechanism. 70 2. Free Radical Mechanism ................................... 72 2. 1 Halogen Abstraction ................................. 72 2.2 Outer-Sphere Electron Transfer. 73 3. Synthesis via Reaction with a Grignard R eag en t ..................................... 74 J . Factors Influencing the Nucleophilicity of Co(l) Sltd its Rate of Alkylation ....................................... 75 K. Study of cis- and trans-effects with the C o rrin o id s .................................................................... 81 L. Study of Transmission of Electronic Effects in Model Cobalt Complexes by NMR T ech n iq u e ........................................................................ 85 1.1 R-Co(in)bis(dimethylglyoximato)* B. R-Co(IH)(D 2 H2)*B ..................................... 86 1. 2 R-Co(III)bis(salicylaldehyde)ethylene- diimine, R-Co(III)(Salen)* B ...................... 89 1. 3 R-Co(III)bis(acetylacetone)ethylenedi- imine, R-Co(III)(BAE) and RCo(III)* (BAE)*B ................................................................ 89 v ii Page 1,4 R-Co(III)(aetioporphyriii I), R-Co(UI)(Etio I) ........................................... 91 1. 5 R-Co(III)(2, 12-dimethyl-3, 7, 11,17- tetraazabicyclo-[ 11, 3. ljheptadeca- 1(17), 2, 11, 13, 15-pentaene, [R-Co- (HlXCR)Br]+ and [R-Co(HI)CR]2+. .. 91 1.6 [R-Co(III)(2, 3,9, 10-tetramethyl- 1.4.8, 11 -tetraazacyclotetradeca- 1.3.8, 10-tetraene)X]z+, [R-Co(ni)- (T IM )X ]Z+....................................................... 92 1. 7 [ R ,R ” -C o (III){2, 3, 9, 10-tetram ethyl- 1 ,4 , 8, 11-tetraazacyclotetradeca- 1, 3, 8, 10-tetraene)]1+. [R,R"-Co(III)* (TIM)]1+, (R,RM = CH3) and [R .R11- Co(ni)(2, 12-dimethyl-3, 7, 11, 17- tetraazabicyclo[ 11. 3. l]heptadeca- 1(17), 2, 11, 13, 15-pentaene]»+, [R, R"-Co(in)(CR)]i+ ....................................... 94 1.8 [Co(III)-(5, 7,7, 12, 14, 14-hexamethyl- 1,4,8, 11 -tetraazacyclotetradeca-4, ll-d ie n e )X 2] 1+, [Co(III)( 1, 7-CT)X 2] l+ , and [Co(m)-(5, 7, 7, 12, 14, 14-hexa- methyl- 1,4,8, 11-tetraazacyclotetra- decane)Xz]1+, (tet a and tet b are the meso and racemic isomers of the re­ duced CT-macrocycle, respective­ ly) ......................................................................... 94 M. Electrochemical Studies on Macrocycles. 96 1. P o r p h y r i n s ................................................................ 96 1. 1 Electrochemical Oxidation Behaviour of Metalloporphyrins .................................. 98 1.2 Electrochemical Reduction of Metallo­ p o rp h y rin s ........................... ......................... 110 v iii Page 1,3 Brief Review of Fe-Porphyrin Electrochemistry .............................. 116 2. Phtalocyanines ............................................... 120 3, Other Macrocycles ....................................... 124 3. 1 Electrochemical Behaviour of Macrocycles with no Axial Metal-Carbon Bond .......................... 125 3,2 Electrochemistry of the Vita­ m in B t 2 Model Compounds. , . 136 Statement of Problem ............................................... 139 M ethod of..................................A p p ro a c h ................................................. 141 Macrocycles ................................................................................................