The photochemical dimerization of norbornadiene using chromium carbonyls by Brian Kellog Hill A thesis submitted to the Graduate Faculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY in Chemistry Montana State University © Copyright by Brian Kellog Hill (1969) Abstract: Norbornadiene has previously been shown to undergo dimerization photochemically with Group VI and VIII and thermally with Group VIII unsubstituted metal carbonyls. Furthermore, diene-iron-tricarbonyls cause the reaction to be more stereospecific and give only two products instead of the usual eleven obtained using the unsubstituted metal carbonyls. To learn if this change in products was generally characteristic of unsubstituted and substituted metal carbonyls a series of chromium carbonyls were investigated. The products of the chromium metal carbonyls were three trans dimers, a saturated cage dimer and one ketone insertion product. A possible mechanism for the photochemical dimerization of norbornadiene using chromium hexacarbonyl and substituted chromium carbonyl as sensitizers was determined. A common intermediate for the reactions has been proposed. THE PHOTOCHEMICAL DIMERIZATION OF NORBORNADIENE USING CHROMIUM CARBONYLS' by BRIAN KELLOGG HILL A thesis submitted to the Graduate Faculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY in , C h em istry Approved: Head, Major Department CHairmanT ExaumhingC om m ittee MONTANA STATE UNIVERSITY Bozeman,' Montana August, 1969 ill ACKNOWLEDGEMENT The author would like to acknowledge Dr..E. W. Jennings for his encouragement and advice, without which this research would not have been completed. Special recognition is due the author's wife, Gayle, for her confi­ dence and sacrifices. Appreciation is expressed to the National Defense Education Act for the financial assistance of a fellowship. iv TABLE OF CONTENTS Page LIST OF TABLES .....................................i . ■....................................... ......................... v i LIST OF FIGURES .......................................................................................................... v ii ABSTRACT ..... ................................................................................' ........................ x IN T R O D U C T IO N ............................................................................................................. I D IS C U S S IO N ................................................................................................ '.................. 25 Procedure for Determining Products and Product R atios ....................................................................................................................... 27 Isolation of Intermediates Using Chromium Hexacarbonyl ............. ■......................................... ■................................................ 34 Isolation of Intermediates for Benzene, Toluene or M e sity le n e Chromium T ric a rb o n y l............................................................... 41 O th er I n v e s t i g a t i o n s ......................................................................................... 56 CONCLUSION ................................................................................................................. 60 EXPERIMENTAL..............................................' .....................' ........................................ 70 R e a g e n ts .................................................................................................................... 70 Instruments ........................................................... 71 Light and Reaction Systems ............................................................................ 72 Photoreaction for Determining Products and Product R atios ............................................................................................................. ... 73 Isolation of Photoreaction Intermediates ................................. .... 81 Photochemical Time Study ............................................................................... 85 B eer's L a w ................................................................................ 86 In frared S t u d y ....................................................................................................... 86 Thermal Reaction of Chromium Hexacarbonyl and Norbornadiene .................................................... 86 Irradiation of Norbornadiene Without Metal C arbonyl ...........................87 P h o to re a c tio n of N o rb o rn e n e ..................................................... 87 V Page EXPERIMENTAL (continued) Thermal Reaction of Pyridine Chromium Pentacarbonyl and Norbornadiene ......................................................................................... 87 Thermal Reaction of Dipyridine Chromium Tetracarbonyl and Norbornadiene ........................................................ 88 Isolation of Carbonyl Polym er .................................................................. 89, LITERATURE CITED 90 v i LIST OF TABLES Page I. Transition Complexes With Norbornadiene ........................................ 14 II. Dimers, Trimers and Ketones of Norbornadiene .............................. 15 III. Metal Carbonyl Reactant Templates . ........................................... 25 IV. Experimental Procedure for Product Identification ........................... 2 8 V. P roduct R atios o f N orbornadiene D im e rs ............................................... 32 VI. Peak Assignments for the Mass Spectrum of the Red C om plex ................................................................................................................. 50 v ii LIST OF FIGURES Page 1. Pictorial Representation of the Bond Between Platinum and Ethylene ..................................................... .......................... 4 2. Pictorial Representation of a Metal Carbonyl Bond ....................... 7 3. S tru ctu re o f a Bridged and T riple Bridged C a r b o n y l........................ 8 4. Non-concerted Mechanism for the Formation of N o rb o rn ad ien e D i m e r s ............................................... 23 5. Nuclear Magnetic Resonance Spectra of N o rb o rn ad ien e D i m e r s ................................................................................... 29 6. Nuclear Magnetic Resonance Spectrum of N o rb o rn ad ien e C age D i m e r ......................................................................... 30 7. Infrared Spectrum of Chromium Hexacarbonyl Solution at Zero. Time of Irradiation ................................. ... 36 8 . Infrared Spectrum of Chromium Hexacarbonyl Solution after Two Hours of Irradiation . .............................. ... 3 6 9. Infrared Spectrum of Chromium Hexacarbonyl S o lu tio n a fte r Six H ours of I r r a d i a t i o n .................................................... 37 10. Infrared Spectrum of Chromium Hexacarbonyl Solution after Two Hours of Irradiation and Six H ours in th e D a r k ................................................................................'. ■ 39 IT. Infrared Spectrum of Mesitylene Chromium T ricarbonyl S olution a t Zero Time o f I r r a d i a tio n .............................. 43 12. Infrared Spectrum of Mesitylene Chromium Tricarbonyl Solution after 30 Minutes of Irradiation .................... 43 13. Infrared Spectrum of Mesitylene Chromium Tricarbonyl Solution after One Hour of Irradiation ....................... 44 14. Infrared Spectrum of Mesitylene Chromium Tricarbonyl Solution after 3^/2 Hours of Irradiation ....................... 44 15. Infrared Spectrum of Mesitylene Chromium Tricarbonyl Solution after 30 Minutes of Irradiation and Six Hours in the Dark .............................. ............................................. 45 v iii P age 16. Mass Spectrum of Norbornadiene Chromium T e tra c a rb o n y l...................................................................................... ' ............... 47 17. In frared Spectrum o f Red C o m p le x ........................... ................................ 48 18. M ass Spectrum o f Red C o m p le x ........................... ................ ................... 49 19. Infrared Spectrum of Benzene Chromium Tricarbonyl a t Zero Time of I r r a d i a t i o n ......................................................................... 52 20. Infrared Spectrum of Benzene Chromium Tricarbonyl a fte r 30 M in u tes o f I r r a d ia tio n .................................................. ............... 52 21. Infrared Spectrum of Benzene Chromium Tricarbonyl after One Hour of Irradiation ..................................................................... 53 22. Infrared Spectrum of Benzene Chromium Tricarbonyl a fte r 31/2 H ours o f Irra d ia tio n .................................................................. 53 . 23. Infrared Spectrum of Toluene Chromium Tricarbonyl a t Zero Time of I r r a d i a t i o n ......................................................................... 54 24. Infrared Spectrum of Toluene Chromium Tricarbonyl a fte r 30 M in u tes o f I r r a d ia tio n ..................................... .............................. 54 25. Infrared Spectrum of Toluene Chromium Tricarbonyl a fte r O ne H our of I r r a d i a tio n ...................................................................... 55 26. Infrared Spectrum of Toluene Chromium Tricabonyl a fte r 3Yz Hours of Irradiation .................................................................