Abstract Die 13 C-NMR-Spektren der Phosphor-und Arsen-ylide (CH 3) 3 P [DOUBLE BOND] CH 2,(C 2 H 5) 3 P [DOUBLE BOND] CH 2,(C 2 H 5) 3 P [DOUBLE BOND] CHCH 3,(CH 3) 3 As [DOUBLE BOND] CH 2,(CH 3) 3 P [DOUBLE BOND] CHSi (CH 3) 3,(CH 3) 3 P [DOUBLE BOND] C [Si (CH 3) 3] 2,(CH 3) 3 As [DOUBLE BOND] CHSi (CH 3) 3 und (CH 3) 3 As [DOUBLE BOND] C [Si (CH 3) 3] 2 werden diskutiert und für (CH 3) 3 As [DOUBLE ...