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OCTOBER 24,1988
Selbin J. Oxovanadium(IV) complexes. Coord. Chem. Rev. 1:293-314, 1966.
[Department of Chemisuy, Louisiana State University, Baton Rouge, LAI
This paper reviews the flurry of interest sur2~ persists in almost all reactions with ligands,
rounding the oxovanadium(IV) species, VO , permitted observations not possible with comin particular the 70 or so papers published
since plexes of atom-ions.
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my more comprehensive review. Complexes
The most obvious new variable available
of V02+ and their examination by X-ray dif- with an oxometal species was the infrared
fraction, infrared spectroscopy, thermodynam- stretching
frequency of the metal.oxygen
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ic (stability) studies, electron spin resonance bond. This frequency (940-1,020 cm- ) instudies, and electronic spectral studies, and at- deed turned out to be sensitive not only to the
tempts at theoretical models, are
8 critically re- nature and strength of the equatorial ligands—
viewed and updated. [The SCP indicates that V02+ complexes are nearly always square
this paper has been cited in over 260 publica- pyramidal with axial oxygen and with occasional transaxial ligands, but in a few cases are
tions.1
distorted tngonal bipyramidal—but
even more
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sensitive to axial ligands. ’ Thus the VO
could serve to generate a ligand series based
upon the strengthening or weakening of the
Joel Selbin
V-0 bond, and the equatorial ligands could
serve to enhance either the “softness” or the
Department of Chemistry
“hardness” of the central metal species. The
Louisiana State University
presence of a single d electron generated not
Baton Rouge, LA 70803-1804
only experimental studies of electronic spectra
and the electron spin resonance (ESR) spectra
but several attempts at theoretical treatment
June 30, 1988 of the molecule-ion system. Increasing numbers of single crystal X-ray diffraction studies
began to rt~veala very short V-O bond length
(1.55-1.76A), but one that was not too sensiIn 1959, when I first became interested in tive to the other ligands.
complexes of oxocations, the most extensively
ThèI~iquentcitation olihis paper undoubtstudied such species 2~
was the dioxouranium(VI) edly arose from its critical nature and its timeor uranyl ion, UO
.My first PhD student, liness in the mid-1960s. There was rapidly inLarry Holmes, and2I began a brief collabora- creasing interest in the preparation of new
tion with Sean P. McGlynn, a molecular spec- transition-metal complexes and their study by
troscopist at Louisiana State University, on a electronic and ESR spectral techniques and in
study of the variation of the symmetric and the growing correlation of such data with preantisymmetric stretching vibrations of the dictive models, such as ligand field and moUO with different ligands. We established lecular orbital theories. Adding to its continued
2~ series that exhibited striking similari- frequent citation no doubt is the absence of
a ligand
ties to the well-known spectrochemical ligand any more recent general review of V02+.
series that had generally been generated from
Later work by many others with V02+, unoptical spectral data. It occurred to me then diminished in quantity, has largely been more
that by studying complexes of molecule-ions, of the same type, simply with new complexes,
in particular oxocations, we would have more until the bioinorganic connections and biohandles on the complexes for studying metal- chemical use of V02+ began to be made. Alligand interactions than there are on com- though no more recent general reviews of
plexes of atom-ions.
V02+ have appeared since my review, there
I believed then—and still believe—that per- have been valuable summaries of selected
haps the best, simplest, and most stable and areas of research, such as the
2~inorganic and
persistent such molecule-cation is VO~,oxo- biochemical aspects of VO electron4 paravanadium(IV) or vanadyl. Thisspecies has the magnetic resonance spin probes. The
added feature of being a “single electron” (d’ roughly 250 references in2~this latter review
beyond closed shells) electronic system; that chapter suggest that VO researchis alive
proved to be a mixed blessing. The very strong. and well and occurring in new and exciting
perhaps triply bonded, oxygen, which readily areas.
I.
2.
3.
4.
SelbIn J. The chemistry of oxovanadium(IV). Chezn. Rev. 65:153-75, 1965. (Cited 385 times.)
Selbin J, Holmes L H & McGIynn S P. Vanadyl complexes. Chein. lad—London 1961:746-7. (Cited 25 times.)
Selbbi J & Holmes LII. complexes of oxovanadium(IV). I. litorg. Nuci. Chem. 24:1111-9, 1962. (Cited 70 times.)
Chiateen N D. Vanadyl(IV) EPR spin probes. Inorganic and biochemical aspects. (Berliner L J & Reuben I, eds.)
Biological magneticresonanen. New York: Plenum Press. 1981. Vol. 3. p. ~3-t 19. (Uncited.)
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