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Reactions of a Ga/P‐Based Frustrated Lewis Pair with H X ( X = F – I), Heterocumulenes R –NC Y ( Y = O, S) and Chalcogens–Adduct Formation and Surprising Stability towards Protolysis
Author(s) -
Uhl Werner,
Possart Josephine,
Hepp Alexander,
Layh Marcus
Publication year - 2017
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201700146
Subject(s) - chemistry , frustrated lewis pair , adduct , steric effects , lone pair , lewis acids and bases , intramolecular force , crystallography , geminal , electron pair , hydrogen bond , stereochemistry , medicinal chemistry , molecule , electron , organic chemistry , physics , quantum mechanics , catalysis
Treatment of the geminal Ga/P‐based frustrated Lewis pair (FLP) Mes 2 P–C(Ga t Bu 2 )=C(H)–Ph ( 1 ) with H X ( X = F, Cl, Br, I) afforded the corresponding adducts 2 with the protons bound to the P and the halide anions coordinated to the Ga atoms. Short intramolecular contacts may indicate P–H ··· X hydrogen bonding interactions. The Br and I compounds ( 2c , 2d ) were accessible in moderate yields even when aqueous solutions of the acids were employed. These unexpected reactions confirm the surprising stability of FLP 1 towards protolysis. Heterocumulenes R –N=C= Y ( Y = O, S) and 1 yielded adducts with two different structural motifs. The N=C= Y groups were coordinated to the FLP either via the C= Y ( Y = S; Ph–N=C=O) or the C=N bonds (Ph–N=C=O, Et–N=C=O). For phenyl isocyanate the C=O bonded isomer was observed in the solid state, while both isomeric forms were detected in solution. Steric shielding and the hardness of the atoms may influence the formation of the respective isomer. Cleavage of the C=S bonds of isothiocyanates was observed for the first time and afforded a sulfur adduct 9a , in which an S atom (electron sextet) was bound to the lone pair of electrons at phosphorus and to the Lewis acidic Ga atom. Four‐membered PCGaY heterocycles resulted, which were also synthesized in high yields by the direct reaction of 1 with propylene sulfide or selenium.