Lewis acidity of tris(pentafluorophenyl)borane: crystal and molecular structure of B(C 6F 5) 3·OPEt 3

• Published in: Inorganic chemistry communications Vol. 3; no. 10; pp. 530 - 533
• Main Authors: Beckett, Michael A, Brassington, David S, Coles, Simon J, Hursthouse, Michael B
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2000
• Subjects: Acceptor number; Borane; Lewis acidity; Organophosphine oxide; X-ray structure; Borane; Lewis acidity; Organophosphine oxide; Acceptor number; X-ray structure
• ISSN: 1387-7003; 1879-0259
• DOI: 10.1016/S1387-7003(00)00129-5

The synthesis and characterisation (IR, multielement NMR spectroscopy) of B(C 6F 5) 3·L {L=CH 3CO·OEt ( 1), Et 3PO ( 2)} are described together with a single-crystal X-ray diffraction study of 2. The latter reveals an angular B–O–P linkage {161.04(16)°} with BO and PO bondlengths of 1.533(3) and 1.4973(17) Å, respectively. Lappert’s Δ ν(CO) and Gutmann’s acceptor number (AN) methods have been applied to 1 and 2 to assess the relative Lewis acidity of B(C 6F 5) 3 which is confirmed as weaker than BF 3. A strong linear correlation has been obtained for Gutmann’s AN and Childs’ 1H NMR Lewis acidity scales.