text: The first metal carbene complex to have been reported was Chugaev's red salt, first synthesized as early as 1925, although it was never identified to be a carbene complex. The characterization of (CO)5W(COCH3(Ph)) in the 1960s is often cited as the starting point of the area and Ernst Otto Fischer, for this and other achievements in organometallic chemistry, was awarded the 1973 Nobel Prize in Chemistry. In 1968, Hans-Werner Wanzlick and Karl Öfele separately reported metal-bonded N-heterocyclic carbenes. The synthesis and characterization of ((CH)CCH)Ta=CHC(CH) by Richard R. Schrock in 1974 marked the first metal alkylidene complex. In 1991, Anthony J. Arduengo synthesized and crystallized the first persistent carbene, an NHC with large adamantane alkyl groups, accelerating the field of N-heterocarbene ligands to its current use.