In the reaction of maltol and its derivatives with a Mo(IV) cyano complex, three new salts were isolated
and characterized by physicochemical measurements. The X-ray single crystal measurements of two salts
of the formula (PPh
4
)
2
[Mo(CN)
3
O(LL)]
3H
2
O, where LL = maltol or ethylmaltol, show a distorted octahe-
dral geometry of the anions. The steric hindrance introduced by the ethyl group changes mainly the inter-
molecular distances in the solid state and the network of hydrogen bonds. All the synthesized salts were
compared and discussed with the family of NO, NN and OO donating [Mo(CN)
3
O(LL)]
n
groups. The role of
the ligand protonation constant on the isolation of the products is presented by the synthesis of a
(PPh
4
)
2
[Mo(CN)
4
O(H
2
O)]
5H
2
O salt.