Auration of an Aryltris [(Triarylphosphine)Aurio(I)] Phosphonium(+) Cation to Give a Hypercoordinate Aryltetrakis [(Triarylphosphine) Aurio(I)] Phosphonium(2+) Dication

Hubert Schmidbaur, Edgar Zeller, Gabriele Weidenhille, Oliver Steigelmann, Holger Beruda

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46 Scopus citations

Abstract

Treatment of (2-methylphenyl)phosphine with tris[(triphenylphosphine)aurio(I)]oxonium(+) tetrafluoroborate(-) affords colorless, air-stable (2-methylphenyl)tris[(triphenylphosphine)aurio(l)] phosphonium(+) tetrafluoroborate(-): (2-MeC6H4)[Ph3PAu]3P+BF4-(1); Me = methyl, Ph = phenyl. The crystal structure features tetrahedral cations with a central phosphorus atom surrounded by three gold atoms and one carbon atom. With the Au-P-Au angles showing only slight deviations from the tetrahedral value and the P-Au-P angles close to linear, the Au-Au distances are too long to allow bonding metal-metal interactions. An analogous arsenic compound (2-MeC6H4)[(Ph3PAu]3As+BF4-(3) is available from (2-methylphenyl)arsine and shows similar properties. Reaction of 1 with [Ph3PAu]+BF4-gives high yields of the colorless, crystalline, air-stable species (2-MeC6H4)[Ph3PAu]4P2+(BF4-)2(2). The dications have a square-pyramidal structure with phosphorus at the center, the o-tolyl group at the apex, and the four gold atoms forming the base with short Au-Au contacts (ca. 3.0 Å). These short distances are held responsible for the ease of formation and stability of this novel hypercoordinate unit. An analogous arsenic compound could not be prepared. Crystal data for 1: a = 13.341 (3) Å, b = 15.363 (3) Å, c = 16.369 (3) Å, a = 107.88 (1)°, γ= 98.17 (1)°, γ-103.09 (1)°, triclinic, space group Pi, Z = 2. Crystal data for 2-4C6H6: a = 13.712 (2) Å, 6 = 17.873 (3) Å, c = 20.748 (2) Å, a = 95.04 (1)°, β= 104.58 (1)°, γ= 96.08 (1)°, triclinic, space group PI, Z = 2.

Original languageEnglish
Pages (from-to)2370-2376
Number of pages7
JournalInorganic Chemistry
Volume31
Issue number12
DOIs
StatePublished - 1992
Externally publishedYes

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