Preparation and Properties of Dimethyltetrafluorophosphate†

Christian Hohenstein and Andreas Kornath*

Department of Chemistry, Ludwig-Maximilians-University, Butenandtstrasse 5-13, 81377 Munich, Germany

Frank Neumann^‡

Department of Chemistry, Technical University of Dortmund, Otto-Hahn-Strasse 6, D-44221 Dortmund, Germany

Ralf Ludwig

Department of Physical Chemistry, University of Rostock, Dr.-Lorenz-Weg 1, 18051 Rostock, Germany and Leibniz Institute for Catalysis at the University of Rostock, Albert-Einstein Strasse 29a, 18059 Rostock, Germany

Inorg. Chem., 2010, 49 (14), pp 6421–6427

DOI: 10.1021/ic902438e

Publication Date (Web): June 18, 2010

Copyright © 2010 American Chemical Society

*E-mail: [e-mail]., †

Dedicated to Prof. Dr. Bernhard Lippert on the occasion of his 65^th birthday.

, ‡

Current address: Innovation GmbH, Alexander Strasse 15, 44137 Dortmund, Germany.

Abstract

Dimethyltrifluorophosphorane reacts with strong fluoride donors, such as CsF, Me₄NF, and Me₄PF, under formation of dimethyltetrafluorophosphates. The salts were characterized by infrared and Raman spectroscopy and in acetonitrile solutions by NMR spectroscopy. The experimental results show that only the trans isomer is formed. Theoretical calculations (B3LYP/6-31+G* and RHF/6-31+G*) of the trans and cis isomer yielded a difference of the Gibbs free energy of 29.4 kJ/mol (B3LPY/6-31+G*). The Me₄N⁺[Me₂PF₄]⁻ crystallizes in the orthorhombic space group Pnmaa = 1303.5(3), b = 799.8(2), and c = 1023.8(4) pm. The phosphorus atom has an octahedral environment with P−C distances of 183.4(3) pm and P−F bond lengths in the range between 166.1(1) and 168.2(1) pm. In the crystal packing, anions and cations are linked via weak fluorine hydrogen contacts forming a three-dimensional network. with four formula units per unit cell and dimensions of