Mass Spectrometric Detection and Fragmentation Patterns of Synthetically Useful Chromium and Tungsten Carbene Complexes
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- 作者：Torsten Weilandt ; Ephraim Grä ; ff ; Jochen F. Schneider ; Alexander W. Koch ; Florian A. Zschoche ; Karl Heinz Dö ; tz ; and Christoph A. Schalley
- 刊名：Organometallics
- 出版年：2005
- 出版时间：July 18, 2005
- 年：2005
- 卷：24
- 期：15
- 页码：3671 - 3678
- 全文大小：199K
- 年卷期：v.24,no.15(July 18, 2005)
- ISSN：1520-6041
文摘
A novel method for the detection of synthetically useful pentacarbonyl chromium andtungsten carbene complexes by electrospray ionization Fourier transform ion cyclotronresonance (ESI-FTICR) mass spectrometry is presented which utilizes the addition of CN-anions to the electrophilic carbene carbon. This method is nondestructive, provided theionization proceeds under soft conditions. The scope and limitations of this method areexamined by utilizing different types of carbene complexes. Depending on the 
-CH acidityof the carbene complexes, [M - H]- anions can be observed either in competition with theCN- adducts or as the only ions, even in the presence of cyanide. Secondary aminocarbenecomplexes exclusively form [M - H]- anions by deprotonation of the NH moiety. The ionsunder study have been mass-selected and subjected to collision-induced decay (CID)experiments in order to examine their fragmentation reactions. CO loss is not the onlyobservable process. Most prominently, 1,2-eliminations and a retro-aldol reaction within asugar carbene complex compete with decarbonylation and thus have rather low activationbarriers. Some reactions can be attributed to coordinatively unsaturated chromium atomsformed through preceding CO losses.
-CH acidityof the carbene complexes, [M - H]- anions can be observed either in competition with theCN- adducts or as the only ions, even in the presence of cyanide. Secondary aminocarbenecomplexes exclusively form [M - H]- anions by deprotonation of the NH moiety. The ionsunder study have been mass-selected and subjected to collision-induced decay (CID)experiments in order to examine their fragmentation reactions. CO loss is not the onlyobservable process. Most prominently, 1,2-eliminations and a retro-aldol reaction within asugar carbene complex compete with decarbonylation and thus have rather low activationbarriers. Some reactions can be attributed to coordinatively unsaturated chromium atomsformed through preceding CO losses.