Self Assembly of Silver(I) Complexes Containing 1,4-Bis[(3-pyridyl)ethynyl]benzene

One-dimensional (1-D) zigzag chains
of {[AgL]­(ClO4)­·0.5Et2O}n (1), {[AgL]­(OTf)·Et2O}n (2), and {[AgL]­(BF4)­·0.5CH3OH}n (3) were obtained
from the reaction of AgClO4, AgCF3SO3, and AgBF4 with
1,4-bis­(pyridine-3-ylethynyl)­benzene (L), respectively,
in similar reaction conditions, whereas it led to the formation of
a 1-D sinusoidal chain of {[AgL(NO3)]·H2O}n (4) and a metallolocycle
of [Ag2L6]­(BF4)2 (5) in a different reaction procedure for the
AgNO3 and AgBF4 cases. Complexes 1–3 form 1-D zigzag chains, and every two chains
are further stacked to
give a pair of chains assisted by weak Ag­(I)···Ag­(I)
and π···π interactions, whereas a single
1-D sinusoidal chain of 4 can only be obtained. Although
the reaction is carried out in a similar reaction as 4 except that BF4– was used instead of
NO3–, a metallocycle of 5 was obtained instead. It is noted that only the bridging L ligands in 5 adopt a syn conformation, whereas those
in 1–4 are in an anti conformation.
In this regard, this work has demonstrated the delicate effects of
anions and reaction conditions on the assembly reactions of complexes 1–5. In addition, we observed a structural
transformation during the heating process for 5. Although
the powder X-ray diffraction pattern of 5 at 210 °C
is similar to that of 3, it cannot be conclusively proven
by powder X-ray diffraction studies at this moment due to the presence
of some mismatches between both patterns of 5 and 3.