Zur Umsetzung von Tri(phenylethinyl)arsan und -stiban

T h e syn thesis o f tr i(p h en y le th y n y l)a rsan e (1) an d -stib an e (7) is d iscussed . O c tac a rb o n y ld i­ c o b a lt reac ts selectively w ith 1 o r 7 to yield the //2-side-on c o -o rd in a te d p h en y le thyny l co m ­ plexes ( P h C = C ) nE [(^2C = C P h ) C o 2(C O )6]3_n (E = As: n = 2: 3, n = 1: 4, n = 0: 5; E = Sb: n = 2: 8; n = 1 : 9 ; « = 0: 10), w hich c o n ta in sterically h in d ered c a rb o n -c o b a lt te tra h e d ra n e c lu s te r un its . 3 gives u p o n heating { ( P h C s C ) 2As[(>72C = C P h ) C o 2(C O )5]}2 (6) a c o m ­ p o u n d c o n ta in in g a six -m em bered C o 2A s2C 2 ring. All new c o m p o u n d s have been ch arac te rized by an aly tical a n d sp ec tro sco p ic d a ta (IR , 'H , l3C N M R ), an d (P h -C = C )A s [(? 72-C = sC -P h )C o 2(C O )6]2 (4) by X -ray analysis.