Komplexe mit Phosphinomethan- und -methanidliganden. XVI. Co-Liganden und Substituentenabhängigkeit der Koordination von Diphosphinomethanidliganden [(R2P)2CX]- an Li+ und Kristallstrukturen von...

Hans H. Karsch, Brigitte Deubelly, Gerhard Müller

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Abstract

The coordination of diphosphinomethanides [(R2P)2CX]- (a: R = Me, X = SiMe3; b: Ph, X = H) to Li+ is shown to depend strongly on the co-ligand on Li+: tetramethylethylenediamine (TMEDA), which occupies two coordination sites at the metal center, causes diphosphinomethanides to bind exclusively via both P donor atoms to Li giving the monomeric diphosphine chelate complexes (TMEDA)Li[(R2P)2CX] (1a,b). With tetrahydrofuran (THF) additional carbanion C ⋯ Li and P ⋯ Li interactions result in the dimeric complexes {(THF)Li[(Me2P)2C(SiMe3)]}2 (2a) and {(THF)Li[(Ph2P)2CH]}2 (2b). This additional C ⋯ Li interaction is relatively strong in 2b (d(LiC) 2.242(8) Å), in which no additional substituents are present at the carbanionic C-atom, thereby reducing the P ⋯ Li interactions. In 2a, on the other hand, the Li ⋯ P interactions are fully developed, as is the case for the related, previously described complex, {(THF)Li[Me2P)3Cl]}2. The structural features of 2b constitute a novel case of diphosphinomethanide coordination, which may be regarded as intermediate between the structure of {(TMEDA)Li[Me2PCH2]}2 and 2a.

Original languageGerman
Pages (from-to)47-59
Number of pages13
JournalJournal of Organometallic Chemistry
Volume352
Issue number1-2
DOIs
StatePublished - 6 Sep 1988

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