Wheel-shaped high nuclear metal clusters of paramagnetic ions, which can be regarded as chains with finite number of metal atoms, have received a substantial interest largely stimulated by their fascinating physical properties, including single-molecule magnets (SMMs) behaviour, as well as their potential applications as nanoscale functional units in the next generation of electronic or spintronic devices. Among different strategies for preparation of metallic wheels the use of alkoxides as chelating and bridging ligands has been successful in many cases. In continue our research on development of large polynuclear iron systems [1-3] an easy way to heterometallic FeLn/Y wheels using trinuclear µ-oxo FeIII pivalate or isobyturate and tetratopic triethanolamine (H3tea) ligand and azide, both capable bridge different types of metal ions, has been developed (Figure 1). The chosen strategy was very successful in producing a family of hexanuclear {FeIII4LnIII2}-type pivalate wheels [Fe4Ln2(piv)6(N3)4(Htea)4]·2(EtOH), LnIII = Dy (1a), Er (1b), Ho (1c), [Fe4Tb2(piv)6(N3)4(Htea)4] (1d), [Fe4Ln2(piv)6(N3)4(Htea)4]·2(dcm), LnIII = Dy (2a), Er (2b), and [Fe4Ln2(piv)4(N3)6(Htea)4]·2(EtOH)·2(dcm), LnIII = Dy (3a), Er (3b), and ultra-large tetraicosanuclear {FeIII18MIII6}-type isobutyrate wheels [Fe18M6(is)12(Htea)18(tea)6(N3)6] n(solvent), MIII = Dy (4, 4a), Gd (5), Tb (6), Ho (7), Sm (8), Eu (9), and Y (10). Single-crystal X-ray crystallography revealed that 4 - 7, 9 and 10 crystallize in the triclinic space group P-1 and 4a and 8 in the trigonal space group R-3. The external diameter of ultra-large wheels is ca. 3.7 nm and the hole is ca. 1 nm. The crystal structure of ultra-large wheels revealed the formation infinite channels filled by solvents molecules. Upon removal of neutral solvent molecules, the triclinic structures reveal a large total potential solvent area volume of ca. 27%, and trigonal one ca. 44% per unit cell volume, as calculated by PLATON.27.                 Figure 1. Scheme showing the syntheses of wheels 1-10.   Acknowledgments. This work was supported by the Swiss National Science Foundation (SCOPES IZ73ZO_152404/1, DAAD (O. I. B.) and State Program of R. Moldova (Project 16.00353.50.05A)