During the isolation of the 2, single crystals of the hydrated salt
2a were obtained by recrystallization from wet THF. Compound 2a
crystallized in the monoclinic space group P21/c with one molecule
of H2O in the asymmetric unit (Table 1). The water molecule in 2a
forms a strong hydrogen bond with the ammonium cation and two
such pairs form a cyclic [NH4$H2O]2
2þ unit (Fig. 2). The two
hydrogen atoms from the water molecule and two hydrogen atoms
from the ammonium group participate in a strong two-center
hydrogen bonds, whereas the remaining two hydrogen atoms for
the ammonium cation are involved in three-centered asymmetric
hydrogen bonds either to two sulfur atoms from the same PS2 unit
or to a sulfur atom and a water molecule, respectively. In total, the
[NH4$H2O]2
2þ cation coordinates to eight sulfur atoms from six
different [S2P{4-(iPr)-OBz}(Fc)] (Bz ¼ benzyl, Fc ¼ ferrocenyl)
anions. This extended coordination mode results in the formation
of a 2D hydrogen bond network located in the 200 plane (Fig. 3). It
is noteworthy, that the formation of an identical [NH4$H2O]2
2þ
cation and an almost identical 2D hydrogen bond network have
been observed earlier in the crystal structures of 5$H2O and
[NH4$H2O][S2P{4-(nBu)-OBz}(Fc)] [13]. The parameters for the
hydrogen bonds in 2a are listed in Table 2