title: Synthesis and structure of K+ [iPrN=C=P]-, a 1-aza-3lambda3-phospha-3-allenide.
abstract: 2-Isopropyl(trimethylsilyl)amino-1lambda3-phosphaalkyne 1 reacts with potassium tert-butoxide to form potassium 1-isopropyl-1-aza-3lambda3-phospha-3-allenide (2). This compound was structurally characterized as the corresponding 18-crown-6 ether complex 3. The molecular structure of 1 was also determined in order to compare the bonding situation in the anion and the neutral lambda3-phosphaalkyne. Compound 3 contains a nitrogen-carbon-phosphorus group for which the parameters were shown by X-ray structural analysis and quantum chemical calculations to lie between the extrema N-C[triple bond]P and N=C=P, suggesting reactivity typical of an ambident anion. This is indeed the case, as subsequent reaction of 2 with chlorotrimethylsilane at nitrogen regenerates the lambda3-phosphaalkyne 1; with chlorotriphenylsilane the new derivative 4 is formed. In contrast, chlorotrimethylstannane reacts at phosphorus, giving the 1-aza-3lambda3-phosphaallene isopropyliminomethylidene(trimethylstannyl)phosphane 5.
authors.affiliation: Institut für Anorganische Chemie der Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany. becker@iac.uni-stuttgart.de
authors.forename: Gerd
authors.initials: G
authors.lastname: Becker
authors.forename: Heike
authors.initials: H
authors.lastname: Brombach
authors.forename: Stephen T
authors.initials: ST
authors.lastname: Horner
authors.forename: Edgar
authors.initials: E
authors.lastname: Niecke
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Schwarz
authors.forename: Rainer
authors.initials: R
authors.lastname: Streubel
authors.forename: Ernst-Ulrich
authors.initials: EU
authors.lastname: Würthwein