Inhaltsu È bersicht. (Me 3 Si) 2 C=PCl (1) reagiert mit den Trichlorsilylphosphanen RR'PSiCl 3 (R, R' = t-Bu oder i-Pr) zu den neuen P-Dialkylphosphanylphosphaalkenen (Me 3 Si) 2 C=P±P-i-Pr 2 (2) und (Me 3 Si) 2 C=P±P(t-Bu)(i-Pr) (3) sowie zu bekanntem (Me 3 Si) 2 C=P±P-t-Bu 2 (4). Eine [2 + 4]-Cycloaddition an die P=C-Doppelbindung von 2 mit Cyclopentadien liefert das P-Phosphanyl-phosphanorbornen-Derivat 5; entsprechend entsteht mit 2,3-Dimethylbutadien das cyclische Diphosphan 6. Die Reaktionen von 2 mit Schwefel und Selen wurden 31 P-und 77 Se-NMR-spektroskopisch verfolgt: Der Chalkogeninsertion in die P±P-Bindung zu den Chalkogenophosphinito-Phosphaalkenen (Me 3 Si) 2 C=P±X±Pi-Pr 2 9 a (X = S) und 9 b (X = Se) schlieûen sich r 3 k 3 → r 4 k 5 -Oxidationsschritte zu den Dichalkogenophosphinato-phosphaalkenen (Me 3 Si) 2 C=P±X±P(=X)-i-Pr 2 10 a (X = S) und 10 b (X = Se) an. 10 a und 10 b konnten nicht rein isoliert werden; es gelang aber, 10 b mit Cyclopentadien in das besta È ndige [2 + 4]-Cycloadditionsprodukt 12 zu u È berfu È hren und zu isolieren. NMR-und Massenspektren belegen die Konstitution von 2, 3, 5, 6 und 12. Die Strukturen der Cycloaddukte 5 und 6 wurden durch Ro È ntgenbeugung am Einkristall bestimmt.
The New P-Phosphanylphosphaalkene 1-Bis(trimethylsilyl)methylidene-2,2diisopropyldiphosphane: First Reactions at its P=C and P±P Bonds Abstract. (Me 3 Si) 2 C=PCl (1) reacts with the trichlorosilylphosphanes RR'PSiCl 3 (R and R' = t-Bu or i-Pr) providing the new P-dialkylphosphanylphosphaalkenes (Me 3 Si) 2 C=P±P-i-Pr 2 (2) and (Me 3 Si) 2 C=P±P(t-Bu)(i-Pr) (3) as well as the known (Me 3 Si) 2 C=P±P-t-Bu 2 (4). The P=C double bond of 2 can be protected reversibly by a [2 + 4]-cycloaddition with cyclopentadiene resulting in the formation of a P-phosphanylphosphanorbornene derivative 5. The [2 + 4]-cycloaddition of 2 with 2,3-dimethylbutadiene provides the cyclic diphosphane 6. Reactions of 2 with sulfur and selenium were followed by 31 P and 77 Se nmr: Chalcogen insertion into the P±P bond leads to the products (Me 3 Si) 2 C=P±X±P-i-Pr 2 9 a (X = S) and 9 b (X = Se). Subsequent r 3 k 3 → r 4 k 5 oxidation steps of 9 a with S and of 9 b with Se lead to compounds (Me 3 Si) 2 ´C=P±X±P(=X)-i-Pr 2 10 a (X = S) and 10 b (X = Se), which contain phosphinic acid functions with the phosphaalkene moieties attached to S or Se. 10 a and 10 b were not isolated in a pure state. However, trapping 10 b from an enriched solution by [2 + 4]-cycloaddition with cyclopentadiene allowed the isolation of the P-diseleno-phosphinato-phosphanorbornene 12. The constitution of new compounds 2, 3, 5, 6 and 12 was confirmed by elemental analyses, nmr and mass spectra. The structures of cycloadducts 5 and 6 were determined by X-ray diffraction analysis.