Structures and Stability of Complexes of E(C₆F₅)₃ (E = B, Al, Ga, In) with Acetonitrile

Abstract

Complexes formed by interaction of E(C6F5)3 (E = B, Al, Ga, In) with excess of acetonitrile (AN) were structurally characterized. Quantum chemical computations indicate that for Al(C6F5)3 and In(C6F5)3 the formation of a complex of 1:2 composition is more advantageous than for B(C6F5)3 and Ga(C6F5)3, in line with experimental observations. Formation of the solvate [Al(C6F5)3·2AN]·AN is in agreement with predicted thermodynamic instability of [Al(C6F5)3·3AN]. Tensimetry study of B(C6F5)3·CH3CN reveals its stability in the solid state up to 197 °C. With the temperature increase, the complex undergoes irreversible thermal decomposition with pentafluorobenzene formation.

Lewis acid–base adducts of Al(N(C6F5)2)3 and Ga(N(C6F5)2)3 – structural features and dissociation enthalpies

“…Similar values are revealed for the acetonitrile adduct of the Lewis superacids Al(OC(C 6 F 5 ) 3 ) 3 15 and Al(C 6 F 5 ) 3 24 and the adducts of the less Lewis acidic AlMe 3 , 25 GaCl 3 26 and Al(OC(CF 3 ) 2 (C 6 H 4 CH 3 )) 3 (Table 2). 27 Even shorter values are shown by Ga(C 6 F 5 ) 3 ·NCMe, 24 [Cp 3 Zr(MeCN)][MeB(C 6 F 5 ) 3 ], 28 GaMes 3 ·NCMe 29 or B(C 6 F 5 ) 3 ·NCMe. 23 The corresponding M–N distances are presented in Table 3.…”

“…The CN stretching vibration frequency of (Al(N(C 6 F 5 ) 2 ) 3 ·NCMe (2313 cm −1 ) exhibits a blue shift compared to free acetonitrile (2253 cm −1 ). 23 This trend has also been observed for acetonitrile adducts of other Lewis acids ([Al(C 6 F 5 ) 3 ·2NCMe]·NCMe: 2340 and 2311 cm −1 , 24 [Cp 3 Zr(MeCN)][MeB(C 6 F 5 ) 3 ]: 2321 cm −1 , 28 SbF 5 ·NCMe: 2335 cm −1 , 30 Al(OTeF 5 ) 3 ·NCMe: 2340 cm −1 , 14 Al(OC(C 6 F 5 ) 3 ) 3 ·NCMe: 2344 cm −1 , 15 bis(perfluoropinacolato)silane·NCMe: 2358 and 2329 cm −1 , 17 B(C 6 F 5 ) 3 ·NCMe: 2367 cm −1 , 23 ). However, the discrepancy of the Lewis acidity and the frequency of the CN stretching mode found in the MeCN adducts has been discussed in the literature.…”

“…31 Only recently Shcherbina et al described the correlation between the square root of the shift of the CN stretching vibration frequency and the donor–acceptor bond energy. 24…”

Influence of the solvent on the Lewis acidity of antimony pentahalides and group 13 Lewis acids toward acetonitrile and pyridine

“…Complexes of E(C 6 F 5 ) 3 with pyridine and acetonitrile are stabilized in solution (with respect to the gas phase) for E = B, Al and destabilized for E = Ga, In. This phenomenon was recently noted by us on the example of E(C 6 F 5 ) 3 ·AN complexes 43 …”

Structural and Energetic Features of Group 13 Element Trispentafluorophenyl Complexes with Diethyl Ether

“…[ 31 ] Recently, a structural study of E(C 6 F 5 ) 3 (E = B, Al, Ga, In) complexes with neutral N‐containing donor acetonitrile was reported by our group. [ 32 ] However, up to now there is no complete series of structurally characterized E(C 6 F 5 ) 3 complexes with the same O‐donor ligand.…”