The synthesis, structural characterisation, electrochemistry, and luminescence properties of a series of alkali metal alcoholates and samarium(III) alkoxides with thiophene-based OR substituents are presented. The alkali metal alcoholates 7-15 were obtained by deprotonation of the carbinol with NaH or KH. Their molecular structures consist of tetranuclear alkali metal alcoholates with a distorted cubane-like M 4 O 4 core (Xray structure analyses). Each alkali metal is surrounded by three carbinolate ligands and (depending on the derivative) by additional tetrahydrofuran molecules. The mononuclear samarium alkoxides {Sm[OC(C 4 H 3 S) 3 ] 3 (thf) 3 }·thf (16) and {Sm[OC(C 16 H 13 S)] 3 (thf) 3 }·thf (17) were synthesised by the salt metathesis reactions between {[KOC(C 4 H 3 S) 3 ] 4 (thf) 2 }·thf (7), [NaOC(C 4 H 3 S) 3 ] 4 (thf) 2 (8) or * Prof. Dr. Dr. h. c. M. Veith E-Mail: Michael.Veith@inm-gmbh.de [a] www.zaac.wiley-vch.de 2263 [NaOC(C 4 H 3 S) 3 ] 4 (thf) 2 (8): All NaH had reacted. The solvent was evaporated; a solid was obtained, from which colorless crystals could be obtained in thf at 5°C. Yield 15 %, 243 mg. 1 H NMR (thf/C 6 D 6 ): δ = 6.9 (dd, 3 J H5-H4 = 4.9 Hz and 4 J H5-H3 = 1.2 Hz, 12H, 5-H), 6.8 (dd, 3 J H3-H4 = 3.4 Hz and 4 J H3-H5 = 1.2 Hz, 12H, 3-H), 6.7 (dd, 3 J H4-H3 = 3.7 Hz and 3 J H4-H5 = 4.9 Hz, 12H, 4-H). C 60 H 52 O 6 S 12 Na 4 : calcd. C 53.50; H 3.86 %; found C 52.24; H 3.56 %. [NaOC(C 14 H 11 S 2 )] 4 (thf) 2 (10): The unreacted NaH was filtered. The solvent was slowly evaporated, a light-brown solid precipitated, which was separated from the liquid residue. The isolated yield is 32 % (529 mg). 1 H NMR (thf/C 6 D 6 ): δ = 7.6 (dd, 3 J H5-H4 = 6.6 Hz and 4 J H5-H3 = 1.3 Hz, 8H, 5-H Th), 7.0 (m, 28 H, 4-H, Ph), 6.7 (dd, 3 J H4-H3 = 4.0 Hz, 8 H, 3-H Th). C 68 H 60 O 6 S 8 Na 4 : calcd. C 61.81; H 4.54 %; found C 60.61; H 4.39 %.[NaOC(C 17 H 15 S)] 4 (thf) 2 (13): The suspension turned into a solution.The solvent was slowly evaporated, a white solid precipitated, which