18‐Crown‐6 and Titanium Tetrafluoride − Preparation of the Ti IV Fluoride Crown Ether Complexes (TiF 4 ) 2 (18‐Crown‐6) and the Stabilization of cis‐ TiF 4 (H 2 O) 2 in [{ cis‐ TiF 4 (H 2 O) 2 } 2 (18‐Crown‐6)]

Reaction of TiF 4 and 18‐crown‐6 in MeCN affords the molecular complex [( cis‐ TiF 4 ) 2 (18‐crown‐6)] ( 1 ) only. Water and THF displace the 18‐crown‐6 in the tetrafluoro complex 1 , with the formation of cis‐ TiF 4 L 2 . The complex cis‐ TiF 4 (H 2 O) 2 and 18‐crown‐6 form [{ cis‐ TiF 4 (H 2 O) 2 } 2 (18‐crown‐6)] ( 2 ), in which cis‐ TiF 4 (H 2 O) 2 and 18‐crown‐6 are connected by hydrogen bonding through the protons of coordinated H 2 O in TiF 4 (H 2 O) 2 and the oxygen atoms of the crown ether. Complexes 1 and 2 were characterized by X‐ray single crystal analysis, elemental analysis, IR, NMR and Mass spectroscopy. The relative basicities of the 18‐crown‐6 and the molecular donor ligands MeCN, THF, H 2 O toward Ti IV fluoride were established by NMR spectroscopic investigations of the substitution reactions. 18‐crown‐6 is slightly more basic than MeCN, similar to that of Et 2 O, and less basic than THF and H 2 O. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)