21-1-1 SHIHC. CHANG,DONGY. PARK,AND NORMAN C. LI The bond distances and angles in the (CeH;)4As+ ion are all close to the normal, accepted value^.^' H o w ever, the angles of rotation of the four phenyl groups about their respective As-C(nl)-C(n4) axes are such t h a t the (C6Hj)4-4s+ion does not approximate to any symmetrical conformation (such as Dzd or SJ. I n some other cases such high symmetries have been f o ~ n d ~ although more or less drastic departures from symmetry
lnovycinic Chernistvy
seem to be coinmon.23s2tiI t is precisely this flexibility which makes (C6H6)&+ such a useful cation for obtaining crystalline salts of large, irregularly shaped anions.
-s,
+
~ s ~ ~ -S,C=NR?
v
0.5-
9, >C-KR2
c.rs4./
VI
(26) 17. A. Cotton and S J. Lippard, I n o ~ g .C i z e n ~ 5, , 416 ( I g 6 6 ) (26) J , G. Bergman, Jr.. and F. A . Cotton, i b i d . , 5 , 1420 (1966).
(23) K. C. L. hiooney, J . Am. Chcin. S o c , 62, 2995 (1940). (24) B. Zaslon and I
