Structural investigations of metalcarbonyl complexes with acyclic diamino carbenes

Here, we report the synthesis of acyclic and cyclic aminocarbene substituted carbonyl complexes of group 6 metals. The reaction of bis(diisopropyl)aminocarbene with photolytically produced (ether)M(CO)₅ leads to unstable η¹-carbene complexes, which convert to η²-carbene complexes; crystallographic data are presented for the tungsten complex, where one amino group of the carbene coordinates to the metal. The Mo and W η²-complexes can be converted to an imine-complex under elimination of propene; characterized by chemical, spectroscopic and crystallographic data. DFT-calculations of a new bis(dialkyl)aminocarbene and the corresponding methylidene salt were performed and compared with the corresponding crystallographic data of the latter one. In a side-reaction during the reaction of (diethyl ether)Cr(CO)₅ with a free six-membered cyclic carbene a three-nuclear dianionic metal carbonyl nido complex (C₁₄H₁₀Cr₃O₁₂)^2- is formed, which could be characterized by spectroscopic and crystallographic data.