The protection of the hydroxy group of 1-hydroxy-2.2.4.5.5-pentamethyl-3-im
idazoline by a t-butyldimethylsilyl group gives the silane 1 which allows v
ia the 4-lithium salt the preparation of 4-substituted derivatives, i.e. a
dithio-carboxylic acid (2), a disulfide (3), a phosphane (4) and a thioethe
r (5). Oxidation of 4-lithiated 1 yields under C-C coupling an ethylene bri
dged bis(3-imidazoline) (6). From these compounds Pd(II) and Pt(II) complex
es M(4)(2)Cl-2 (M = Pd, Pt and Pd(5)Cl-2 were prepared and the structure of
the dithiocarboxylate chelate complex Pd(2-H+)(2) (7) was determined by X-
ray diffraction. Cleavage of the silyl group from 7 gives complex 8 which c
an be oxidized to the corresponding diradical (9). Complex 9 was characteri
zed by its EPR spectrum. Measurements of the magnetic susceptibility of 9 r
eveal strong antiferromagnetic coupling between the two spins at low temper
atures.