The precursor complexes reacted with 4-(2-methoxypyridyl)
phenyldipyrromethene and afforded cyclic dimeric complexes
1 and 2, whereas 4-(3-methoxypyridyl)phenyldipyrromethene or
4-(4-methoxypyridyl)phenyldipyrromethene reacted with aforesaid
metal precursors to form trinuclear complexes 3 and 4
(Scheme 1) via cleavage of the etheratic (C–O) bond [15c].
Therefore, to investigate the possibility of formation of 3 and 4 directly
from the reactions of 4-hydroxyphenyldipyrromethene and appropriate
metal precursor, parallel reactions were run under analogous
conditions. Expectedly, these afforded trinuclear complexes
3 and 4. It prompted us to examine the reactivity of precursor complexes
with 3-/2-hydroxyphenyldipyrromethenes under analogous
conditions (Scheme 1). Interestingly, 3-hydroxyphenyldipyrromethene
gave binuclear complexes 5 and 6, on the other hand
2-hydroxyphenyldipyrromethene gave mononuclear complexes 7
and 8.