E sub(4) Butterfly Complexes (E=P, As) as Chelating Ligands

• Published in: Angewandte Chemie International Edition Vol. 54; no. 44; pp. 13116 - 13121
• Main Authors: Schwarzmaier, Christoph, Heinl, Sebastian, Balazs, Gabor, Scheer, Manfred
• Format: Journal Article
• Language: English
• Published: 01.10.2015
• Subjects: Butterflies; Cations; Diffraction; Ligands; Mathematical analysis; Spectroscopy; Spiro compounds; Stoichiometry
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201506784

The coordination properties of new types of bidentate phosphane and arsane ligands with a narrow bite angle are reported. The reactions of [{Cp'''Fe(CO) sub(2)} sub(2)( mu , eta super(1:1)-P sub(4))] (1a) with the copper salt [Cu(CH sub(3)CN) sub(4)][BF sub(4)] leads, depending on the stoichiometry, to the formation of the spiro compound [{{Cp'''Fe(CO) sub(2)} sub(2)( mu sub(3), eta super(1:1:1:1)-P sub(4))} sub(2)Cu] super( +)[BF sub(4)] super(-) (2) or the monoadduct [{Cp'''Fe(CO) sub(2)} sub(2)( mu sub(3), eta super(1:1:2)-P sub(4)){Cu(MeCN)}] super(+ )[BF sub(4)] super(-) (3). Similarly, the arsane ligand [{Cp'''Fe(CO) sub(2)} sub(2)( mu , eta super(1:1)-As sub(4))] (1b) reacts with [Cu(CH sub(3)CN) sub(4)][BF sub(4)] to give [{{Cp'''Fe(CO) sub(2)} sub(2)( mu sub(3), eta super(1:1:1:1)-As sub(4))} sub(2) Cu] super(+)[BF sub(4) ] super(-) (5). Protonation of 1a occurs at the "wing tip" phosphorus atoms, which is in line with the results of DFT calculations. The compounds are characterized by spectroscopic methods (heteronuclear NMR spectroscopy and IR spectrometry) and by single-crystal X-ray diffraction studies. The butterfly has landed: The first examples of the coordination of E sub(4) butterfly complexes (E=P, As) are presented. It is shown that the "wing-tip" E atoms are capable of acting as ligands towards Cu super(+) cations. The E sub(4) moieties act as bidentate ligands with a very narrow bite-angle, which is comparable to that of dppm (bis(diphenylphosphino)methane).