Abstract
The synthesis and structural characterisation of the triangular incomplete cuboidal dimolybdenum-tungsten cluster aqua ion [Mo
2
W(µ
3
-O)(µ-O)
3
(OH
2
)
9
]
4+
is reported. An X-ray crystallographic study of the derivative complex [NMe
4
]
5
[Mo
2
W(µ
3
-O)(µ-O)
3
(NCS)
9
]·C
6
H
5
Me shows positional disorder at the Mo and W atoms resulting in crystallographically identical metal sites Mo and W in character. Oxygen-17 and molybdenum-95 NMR measurements coupled with redox studies have verified the presence of the mixed cluster in solution. A kinetic study with regard to 1:1 NCS
-
substitution at the water ligands is supportive of reaction occurring at one of the two more labile and statistically identical and independent molybdenum sites promoted through a conjugate base form presumed to derive
via
deprotonation of a water ligand
trans
to the µ-O groups on the same molybdenum atom. Electronic effects on the redox and substitution behaviour at molybdenum arising from the presence of the remote tungsten atom have been detected.