New diphosphopentamolybdate (VI) (
$$\hbox {C}_{6}\hbox {H}_{14}\hbox {N})_{4}$$
C
6
H
14
N
)
4
(
$$\hbox {NH}_{4})_{2}[\hbox {P}_{2}\hbox {Mo}_{5}\hbox {O}_{23}]\cdot \hbox {H}_{2}\hbox {O}$$
NH
4
)
2
[
P
2
Mo
5
O
23
]
ยท
H
2
O
synthesis, crystal structure, experimental and theoretical studies