Translated abstract:
The present thesis shows by means of various examples that diazoalkanes have a versatile preparative applicability in organometallic complex-chemistry. They are not only suitable for the build-up of metal complexes of already known classes of compounds, but also contribute to new synthetic pathways for new complex systems.
A typical example for this are the new methylene complexes μ-CH2[(η-RC5H4)Mn(CO)2]2 [R=H, CH3]. The new 76, from diazoalkanes depicted organometallic compounds, belong to the following classes of complexes:
A) Nitrogen-free compounds
carbene complexes
μ-methylene complexes
alkyl complexes
olefin complexes
acetylene complexes
carbene addition products (metallacycles)
σ-halogen cyclopentadienyl complexes
π-halogen cyclopentadienyl complexes
π-(1-halogen indenyl) complexes
halogen sandwich complexes of the ferrocene type
B) Nitrogen-containing compounds
dinitrogen complexes
σ-coordinated diazoalkane derivatives
cyclic diazoalkane derivatives
alkanediazo complexes
ketimine complexes
iminoamide complexes
The synthesis of η5-halogen cyclopentadienyl- as well as η5-halogen indenyl- complexes of the cymantren type, which is based on diazocyclopentadiene and its derivates and diazoindene respectively, cannot be outbid on simplicity and in most cases even on the yields obtained. Their formation proceeds upon σ-halogen cyclopentadienyl intermediates, which can in some cases also be isolated. In the course of the repetitive cyclopentadienylation, hetero-dihalogenferrocenes can be obtained from (CO)4FeX2 systems.
Acyclic diazo-compounds form preferably carbene- and μ-methylene- complexes, as long as the metal substrates do not contain metal hydride- or metal halogen functionalities for carbene insertion, in which case they react mainly to alkyl- and/or alkandiazo complexes. The formation of cyclic carbene- addition products is bound to the presence of additional basic centres within the diazo-component: Diazo-esther derivatives react in the course of {2+3}-carben additions leading to the formation of five-membered metallacycles.
The formation of complexed carbines occurs when using α-mercuriated diazoalkanes. From the reaction of diazo-acetoester derivatives with bromo-pentacarbonyl-manganese acetylene complexes as well as coordination complexes containing bridged carbine(methylidene) ligands can be obtained.
More seldom even the unfragmented diazomolecules can be fixed on the transition metal centres. These 1:1-adducts are usually quite unstable substances, which indicates their dominat “first step” intermediate character in the organometallic chemistry of the diazoalkanes.
The extensive amount of complexes already synthesised within a wide scope of organometallic complex chemistry cannot hide the fact that the mechanisms for these reactions are only partially known. Many detailed questions still await their presumably difficult clarification. Thus, the future of the organometallic diazoalkane chemistry, beyond the promising preparative advancement, has also to be dedicated to extensive mechanistic studies.