Аннотация:Using the recent aromatic criteria, the conjugation and aromatic properties of5 group 4 metallacyclocumulenes Cp2M-η4−(R)C-CC-C−R (1) and Cp2M-η3(R−C-CC-C(R)−R(C)=CR) (2) (M = Ti, Zr, Hf) were studied. To these nontrivial bonded7 metallacycles, the most recent universal criteria of aromaticity were applied that do not8 require any parametrisation such as isomerisation stabilization energy, electron density of9 delocalized bonds (EDDB), nuclear independent chemical shift, and gauge-included10 magnetically induced currents (GIMICs). All methods used indicated the absence of the11 common π-type aromaticity. The most efficient EDDB and GIMIC methods showed in-plane12 aromatic pathway in 5-membered cycle 1 against 7-membered 2. The distribution of the13 induced currents (ICs) for such unique aromaticity type was demonstrated. It shows that the diatropic ICs of 1 are located both14 inside and outside the cycle. The population analysis of molecular orbitals and natural orbitals for delocalized bonds revealed the15 abidance to the 4n + 2 electron rule. According to EDDB and GIMIC data, the degree of aromaticity for 1 tends to decrease from Ti16 to Zr and Hf.