Guanidinium Perfluoridotitanate(IV) Compounds: Structural Determination of an Oligomeric [Ti6F27]3– Anion, and an Example of a Mixed‐Anion Salt Containing Two Different Fluoridotitanate(IV) Anions. Issue 48 (17th December 2018)

• Record Type: Journal Article
• Authors: Shlyapnikov, Igor M.; Goreshnik, Evgeny A.; Mazej, Zoran
• Is Part Of: European journal of inorganic chemistry. Issue 48(2018)
• Page Start: 5246
• Page End: 5257
• Publication Date: 2018-12-17
• Subjects: Guanidine -- Titanium -- Crystal structure -- Fluorides -- Hybrid compounds; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201801207
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract : Chemical reactions between guanidinium carbonate or guanidinium chloride and titanium tetrafluoride in anhydrous hydrogen fluoride (aHF) were studied. The obtained products were recrystallized from saturated HF, SO2 and CH3 CN solutions. Single‐crystal growths resulted in the detection of seven perfluoridotitanate(IV) compounds, which were structurally characterized. Three of them correspond to the phases obtained as the main products of the synthesis in aHF, i.e., [C(NH2 )3 ]2 [TiF6 ], [C(NH2 )3 ]4 [Ti4 F20 ], and [C(NH2 )3 ][Ti2 F9 ]. When the guanidinium salt/TiF4 molar ratios were greater than 1:2, the resulting products were only sparingly soluble or completely insoluble in aHF. Therefore, single‐crystal growths were attempted from other aprotic solvents (SO2 and CH3 CN). Single crystals of [C(NH2 )3 ]3 [Ti6 F27 ]· SO2 were detected in the case of the former and [C(NH2 )3 ]4 [H3 O]4 [Ti4 F20 ][TiF5 ]4 in the case of the latter. The presence of [H3 O] + can be explained by a contamination with traces of H2 O, which is protonated in the superacid aHF. The same reason applies to the formation of the by‐products [H5 O2 ]4 [Ti8 F36 ] and β‐[H3 O][Ti2 F9 ]. The crystal structures of the new guanidinium‐perfluoridotitanate(IV) compounds consist of oligomeric [Ti4 F20 ] 4–, [Ti6 F27 ] 3– and [Ti8 F36 ] 4–, as well as polymeric ([TiF5 ] – )∞ and ([Ti2 F9 ] – )∞ perfluoridotitanate(IV) anions. The hexameric [Ti6 F27 ] 3– anion with a trigonal prismatic geometry was structurally determined for the first time. The crystal‐structure determination of the [C(NH2 )3 ]4 [H3 O]4 [Ti4 F20 ][TiF5 ]4 revealed the first example of a mixed‐anion perfluoridotitanate(IV) compound containing two different perfluoridotitanate(IV) anions, i.e., oligomeric [Ti4 F20 ] 4– and 1‐D polymeric ([TiF5 ] – )∞ anions. The crystal structure of the guanidinium hydrogen difluoride salt [C(NH2 )3 ][HF2 ] is also reported. Abstract : Chemical reactions between guanidinium carbonate or guanidinium chloride and TiF4 in anhydrous HF and further crystallization of the obtained products from saturated HF, SO2 and CH3 CN solutions yielded single crystals of eight compounds. Besides the already known perfluoridotitanate(IV) anions, the obtained compounds reveal the first example of the hexameric discrete anion [Ti6 F27 ] 3– and the first case of a mixed‐anion compound containing both discrete oligomeric and 1‐D polymeric fluoridotitanate anions, where the previously known ([TiF5 ] – )∞ appears in a new conformation.