Density Functional Calculations of Metal Clusters: Structure, Dynamics, and Reactivity - Metallic Systems: A Quantum Chemist's Perspective - page 308

V 3 O

∆ E (eV)

2S + 1= 2 2S + 1= 4

1.900 Å

2.180 Å

0.72

2.240 Å

2.140 Å

1.800 Å

2.143 Å

0.40

1.794 Å

2.051 Å

0.0

FIGURE 9.18 Ground-state.and.low-lying.structures.of.V 3 O.clusters..Bond.lengths.are.in.
Å. and. energy. differences. are. in. eV.. (Reprinted. from. Calaminici,. P.. et. al.,. J. Chem. Phys .,.
118(11),.March.15,.4913,.2003..With.permission.)

unequivocally.the.ground-state.structure.of.V 3 O.and.V 3 O − .as.a.planar.C 2v .structure.
on.the.doublet.and.singlet.PES,.respectively.[183]..Detailed.information.about.how.
the.computations.were.performed.is.given.in.Ref..[184]..In.Figures.9.18.and.9.19,.the.
results.of.the.optimized.structures.of.V 3 O.and.V 3 O − .are,.respectively,.summarized..
The.calculated.bond.distances.are.reported.in.Å.
Both. V 3 O. and. V 3 O − . ground. states. have. planar. C 2v . structures. with. the. oxygen.
atom.bridging.two.vanadium.atoms.(Figures.9.18.and.9.19)..This.result.is.in.perfect.
agreement.with.the.hypothesis.that.the.neutral.and.anionic.V 3 O.clusters.have.planar.
structures. with. doubly. bridging. oxygen. atoms. [128].. The. ground-state. structure.
of. neutral. V 3 O. could. be. assigned. from. our. calculation. to. a. 2 B 2 . state. [128,183]..
The. calculated. vanadium-oxygen. bonds. are. 1.794. Å,. the. two. equal. vanadium-
vanadium.bonds.are.2.051.Å,.and.the.other.metal-metal.bond.is.longer.by.about.
0.5. Å. (Figure. 9.18).. A. planar. C 2v . structure. in. the. quartet. PES. is. found. at. 0.4.eV.
above. the. ground-state. structure.. For. this. structure,. the. vanadium-oxygen. bonds.
are.very.similar.to.those.of.the.ground-state.structure.while.the.metal-metal.bonds.
are.slightly.different.(0.1.Å.longer)..A.three-dimensional.C s .structure.in.the.doublet.
PES.lies.0.72.eV.above.the.ground-state.cluster..In.this.structure,.the.oxygen.atom.
bridges.two.vanadium.atoms.giving.two.equal.V-O.bonds.of.1.90.Å.and.one.V-O.
bond.of.about.0.3.Å.longer..Two.V-V.bonds.are.2.14.Å.and.the.V-V.bond.on.which.
the.oxygen.atom.is.bridged.in.2.24.Å.(Figure.9.18)..We.assigned.a. 1 A 1 .state.as.the.