A study of the reactlons of the halocarbonyls. Mo(co) x (x = cl. Br) with various alkyl amines

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Date
2014-07-07
Authors
Mahungu, Simon Maina
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Abstract
This thesis describes the reactions of dihalotetracarbonylmolybdenum (II), Mo(CO)4X2 eX=Cl.Br). Complexes with various alkrl amines. The aim of the project was to find out whether these halocarbonylsreact via a solvolytic or a redoxy mechanism with alkyl amines. The highly reactive halocarbonyls, MoeCO)4x2' were prepared following literature methods. These halocarbonyls reacted with neat piperidine giving the zerovalent molybdenum complex. tetracarbonylbis(piperidine)molybdenum(O),Mo(CO)4(CSHIONH)2• The amine salt,CsH10NH.HX, for the respective halogen was isolated. The NMR spectrum of the basic distillate from the reaction mixture showed a singlet signal at ~=6.lppm which is '.itnh'e olefinic region. The signal was not affected by deuterating the distillate with deuterated water. When the reaction was carried out using either tetrahydrofuran (T.H.F.) or methanol which had been cooled in dry-ice/acetone mixture as solvents, the same products as those mentioned above were obtained. Treatment of the halocarbonyls, Mo(CO)4X2 (X~Cl,Br), with neat butylamine or propylamine which had been cooled in dry-ice/acetone mixture gave the trisubstituted zerovalent molybdenum'complexes, Mo(CO)3L3 (L = butylamine, propylamineJ. The NMR spectrum .of each .basic distillate from t h e s n reaction mixtures showed a singlet signal at ~= 5.B ppm for butylamine reaction and at =5.3 ppm for propylamine reaction. The s e sin g let s i gilaIs are i nth e ole fin i c region thus showing that the amines have been dehydrogenated. These signals were not affected by deuterating the distillates with deuterated water. The zerovalent molybdenum complex, t r i s (but Y I ami n e )t r i car bon y Imol y b den uIII ( 0 )" was al so is 01 ate d when the h~locarbonyl, Mo(CO)4Br2" was treated with butylamine/methanol mixture. This mixture had been cooled in dry-ice/acetone mixture before being add~d onto thehalocarbonyl, Mo(CO)4Br2. The infrared spectra of the zerovalent molybdenum complexes have been studied. Various assignments for the carbonyl stretching modes have been mad~, The N-H stretching frequency of the coordinated amine was found to be significantly lower than th~t for th~ free ~min8. A careful analysis of the NMR spectra shows that pip e rid i n ere act s wit h the h a I0 Co r bon y Is: M 0 (C 0 )4 X 2 forming 1,4,5,6-tetrahydroanabasine. The high reactivity of the enamines formed from butylamine and propylamine made it impossible to isolate any identifiable organic products. Th8 present wor k h e s SllOWIl Lh e t tile halocarbonyls, ~10 ( CO) 4X2 (X = C1, [l r ) r 0 act wit 11 a,1kYla III i n e s vi a a redoxy mechanism. •
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Department of Chemistry, 80p. 1987
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