{"status":"public","abstract":[{"lang":"eng","text":"Six cluster salts which consist of hexanuclear cluster anions [Nb6Cl12iX6a]2– (X = Cl or Br) and protonated crown ether molecules (15-crown-5 (15cr5) and 12-crown-4 (12cr4)) or crown ether-stabilized oxonium cations as well as one compound consisting of neutral cluster units, [Nb6Cl16(H2O)2]·4 dioxane, were synthesized in good to high yields. The single-crystal X-ray structures of six of these compounds were determined. The cation/anion ratios and the bond distances confirm in all cases oxidized cluster cores with 14 cluster-based electrons. The cations of the cluster salts are either sandwich-type dimers of the formula [(15cr5)H]22+ or [(15cr5)(H3O)]22+ with the protons or oxonium ions embedded in between the crown ether rings or monomeric units in the case of [(12cr4)H]+. 1H NMR investigations show that the cluster salts are strong Brønsted acids. The fact that the cluster core of [Nb6Cl16(H2O)2]·4 dioxane is oxidized but still carries water ligands indicates that within the multi-step reaction sequence of the formation of the cluster-supported acids, the oxidation step happens much faster than the ligand exchange steps. Temperature-dependent 2H MAS NMR spectra of deuterium-exchanged [(15cr5)H]2[Nb6Cl18]·2 CHCl3 are indicative of dynamic processes of the hydrogen-bonded protons within the crown ether molecule. Six cluster salts which consist of hexanuclear cluster anions [Nb6Cl12iX6a]2– (X = Cl or Br) and protonated crown ether molecules (15-crown-5 (15cr5) and 12-crown-4 (12cr4)) or crown ether-stabilized oxonium cations as well as one compound consisting of neutral cluster units, [Nb6Cl16(H2O)2]·4 dioxane, were synthesized in good to high yields. The single-crystal X-ray structures of six of these compounds were determined. The cation/anion ratios and the bond distances confirm in all cases oxidized cluster cores with 14 cluster-based electrons. The cations of the cluster salts are either sandwich-type dimers of the formula [(15cr5)H]22+ or [(15cr5)(H3O)]22+ with the protons or oxonium ions embedded in between the crown ether rings or monomeric units in the case of [(12cr4)H]+. 1H NMR investigations show that the cluster salts are strong Brønsted acids. The fact that the cluster core of [Nb6Cl16(H2O)2]·4 dioxane is oxidized but still carries water ligands indicates that within the multi-step reaction sequence of the formation of the cluster-supported acids, the oxidation step happens much faster than the ligand exchange steps. Temperature-dependent 2H MAS NMR spectra of deuterium-exchanged [(15cr5)H]2[Nb6Cl18]·2 CHCl3 are indicative of dynamic processes of the hydrogen-bonded protons within the crown ether molecule."}],"type":"journal_article","publication":"Inorganic Chemistry","language":[{"iso":"eng"}],"extern":"1","user_id":"100715","_id":"63994","citation":{"short":"J. Koenig, T. Gutmann, G. Buntkowsky, M. Koeckerling, Inorganic Chemistry 61 (2022) 15983–15990.","bibtex":"@article{Koenig_Gutmann_Buntkowsky_Koeckerling_2022, title={Strong Cluster-Supported Brønsted Acids: Hexanuclear Niobium Cluster Compounds with Protonated Crown Ether Cations: (Crown-H)2[Nb6Cl12iX6a] (X = Cl or Br) and the Intermediate [Nb6Cl16(H2O)2]·4 dioxane}, volume={61}, number={40}, journal={Inorganic Chemistry}, publisher={American Chemical Society}, author={Koenig, Jonas and Gutmann, Torsten and Buntkowsky, Gerd and Koeckerling, Martin}, year={2022}, pages={15983–15990} }","mla":"Koenig, Jonas, et al. “Strong Cluster-Supported Brønsted Acids: Hexanuclear Niobium Cluster Compounds with Protonated Crown Ether Cations: (Crown-H)2[Nb6Cl12iX6a] (X = Cl or Br) and the Intermediate [Nb6Cl16(H2O)2]·4 Dioxane.” <i>Inorganic Chemistry</i>, vol. 61, no. 40, American Chemical Society, 2022, pp. 15983–15990.","apa":"Koenig, J., Gutmann, T., Buntkowsky, G., &#38; Koeckerling, M. (2022). Strong Cluster-Supported Brønsted Acids: Hexanuclear Niobium Cluster Compounds with Protonated Crown Ether Cations: (Crown-H)2[Nb6Cl12iX6a] (X = Cl or Br) and the Intermediate [Nb6Cl16(H2O)2]·4 dioxane. <i>Inorganic Chemistry</i>, <i>61</i>(40), 15983–15990.","ama":"Koenig J, Gutmann T, Buntkowsky G, Koeckerling M. Strong Cluster-Supported Brønsted Acids: Hexanuclear Niobium Cluster Compounds with Protonated Crown Ether Cations: (Crown-H)2[Nb6Cl12iX6a] (X = Cl or Br) and the Intermediate [Nb6Cl16(H2O)2]·4 dioxane. <i>Inorganic Chemistry</i>. 2022;61(40):15983–15990.","chicago":"Koenig, Jonas, Torsten Gutmann, Gerd Buntkowsky, and Martin Koeckerling. “Strong Cluster-Supported Brønsted Acids: Hexanuclear Niobium Cluster Compounds with Protonated Crown Ether Cations: (Crown-H)2[Nb6Cl12iX6a] (X = Cl or Br) and the Intermediate [Nb6Cl16(H2O)2]·4 Dioxane.” <i>Inorganic Chemistry</i> 61, no. 40 (2022): 15983–15990.","ieee":"J. Koenig, T. Gutmann, G. Buntkowsky, and M. Koeckerling, “Strong Cluster-Supported Brønsted Acids: Hexanuclear Niobium Cluster Compounds with Protonated Crown Ether Cations: (Crown-H)2[Nb6Cl12iX6a] (X = Cl or Br) and the Intermediate [Nb6Cl16(H2O)2]·4 dioxane,” <i>Inorganic Chemistry</i>, vol. 61, no. 40, pp. 15983–15990, 2022."},"intvolume":"        61","page":"15983–15990","year":"2022","issue":"40","title":"Strong Cluster-Supported Brønsted Acids: Hexanuclear Niobium Cluster Compounds with Protonated Crown Ether Cations: (Crown-H)2[Nb6Cl12iX6a] (X = Cl or Br) and the Intermediate [Nb6Cl16(H2O)2]·4 dioxane","author":[{"first_name":"Jonas","last_name":"Koenig","full_name":"Koenig, Jonas"},{"first_name":"Torsten","id":"118165","full_name":"Gutmann, Torsten","last_name":"Gutmann"},{"first_name":"Gerd","last_name":"Buntkowsky","full_name":"Buntkowsky, Gerd"},{"first_name":"Martin","full_name":"Koeckerling, Martin","last_name":"Koeckerling"}],"date_created":"2026-02-07T15:48:14Z","volume":61,"publisher":"American Chemical Society","date_updated":"2026-02-17T16:16:07Z"}