Bis(1,2,3-trimethylindenyl)iron(III) 2,3-Dicyanonaphtho-1,4-quinonide, a Non-Metallocene, Charge-Transfer Salt Metamagnet with Complementary Donor−Acceptor Geometries

Bis(1,2,3-trimethylindenyl)iron(III) can be paired with 2,3-dicyanonaphtho-1,4-quinone to give an air-stable π-stacked metamagnet
with Tc = 4.1 K, the first example of a non-metallocene CT salt
magnet in this class. A single crystal X-ray structure of the Fe(1,2,3-Me3C9H4)2[DCNQ] salt indicates that it consists of stacks of
alternating donors and acceptors, in which the DCNQ ring systems
are aligned with indenyl groups above and below, and the long
axes of the DCNQ and the indenyl ligand are parallel to each
other. This arrangement suggests that the magnetic properties arise
from favorable interactions due to geometric similarities between
the donor and acceptor, and not from a unique property of the
donor itself.