All approaches to use elements of the first transition metal series for olefin metathesis face certain intrinsic challenges that need to be addressed in order to devise an active catalyst: (i) The metal-carbene (M=CR 2 ) bond tends to be weaker in 3d metal systems than in 4d/5d transition metal systems. This fact leads to cyclopropanation being the preferred reaction in first row transition metal (carbene) complexes. (ii) While heavier metals such as Ru and Mo favour low-spin closed shell configurations, first row metals usually exhibit a wide range of possible spin states, which are close in energy. (iii) Surface crossings between singlet and triplet states are likely to take place. (iv) Open shell systems hamper the coordination of an olefin and could very likely also undergo other radical reactions. However, in the absence of experimental data, theoretical studies can aid to guide experimental synthesis, predict trends and patterns, and exclude unsuitable systems. Due to the complex electronic structure and the multitude of accessible spin states in Mn (and Fe) systems, the computational chemist faces the problem of accurately describing these states and their relative energies. For these reasons, it is not surprising that the first Fe systems to show activity in OM were discovered years after their computational exploration. In this contribution, we explore the feasibility of low-valent manganese alkylidene species complexated by mono-, bi-and tridentate ligand-systems for potential use in OM by means of density functional theory. The focus is on the comparison of isostructural Fe/Mn systems, as well as on the conception of systems that are building upon already synthetically viable precursors.