Synthesis and X-ray structures of new concave π-prismand hydrocarbon [2.2.1]m,p,p- and [2.2.1]p,p,p-cyclophanes
Abstract
The
synthesis of the smaller analogues of the well-known [2.2.2]p,p,p-cyclophane (1) π-prismand were performed ia a well-established
pyrolysis route from the corresponding disulfones. In spite of their smaller size and increased
rigidity, these cyclophanes showed remarkably similar complexation behaviour with Ag+ ions compared to [2.2.2]p,p,p-cyclophane.
X-Ray crystal structure determinations showed the bis-sulfide 12
(1,10-dithia[3.3.1]m,p,p-cyclophane) to be helically
chiral. The single crystal X-ray analysis showed that the reduction of the ring size from 17-membered hydrocarbon 17 to 16-membered hydrocarbon 16 has only a slight effect on the size and shape of the cavity. In the
Ag+ complex of [2.2.1]m,p,p-cyclophane (18) the interaction between silver and hydrocarbon is accomplished by the coordination
of silver to one double bond in two phenyl rings and to only one carbon of the third phenyl ring. However,
in the case of [2.2.1]p,p,p-cyclophane–Ag+ triflate (19), silver is bonded to one of the double bonds in each
phenyl ring. Similarly to larger [2.2.2]cyclophanes the conformations of the parent [2.2.1]m,p,p- (16) and [2.2.1]p,p,p-cyclophanes
(17)
do not change
dramatically upon the complexation with the Ag+ ion.