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Dimitri
V. Zagorevski
Director
Mass Spectrometry Facility
Cogswell 209C
518.276.2149
zagord@rpi.edu |
Dr. Zagorevski received a B.S. and an M.S. from Moscow State
University in Moscow, Russia. He received his Ph.D. from the Institute
of Organoelement Compounds at the Academy of Sciences of Russia
in 1981, where he also was a Junior Research Fellow. He joined
Rensselaer's staff in 2001 as Director of the Mass Spectometry
Facility.
Curriculum Vitae - Dr.
Dimitri V. Zagorevski
My general interests are in gas phase ion chemistry of organometallic
and organic compounds. Mass spectrometry methods provide unique
information about structure and reactivity of ions and neutral
molecules. One of the most important applications of mass spectrometry
is to study species that are unstable in conditions of "regular"
chemical experiments. The majority of my projects was aimed at
the generation of reaction intermediates and at the study of their
reactivity in the gas phase by mass spectrometry methods.
The mass spectral behaviour of a large number of transition
metal p-complexes was studied. In the
majority of these systems the transition metal atom is the centre
of the localization of the positive charge. This causes the following
effects: (i) metal-containing ions are predominantly formed as
a result of fragmentation reactions; (ii) even-electron non-metal-containing
species are presumably lost; (iii) a positively charged metal
atom induces a number of new (relative to non-metal-containing
analogues) dissociations, which are usually characterized by a
high regio- and stereo-selectivity. The results of our studies
in this field, together with the observations of other authors,
were summarized in our review (Yu.S.Nekrasov, D.V.Zagorevski,
Org. Mass Spectrom., 1991, 26, 733) and in
the book Applications of Mass Spectrometry to Organic Stereochemistry,
VHC Publishers, 1993, Ch. 22, p. 657. A summary of applications
of mass spectrometry to coordination and organometallic chemistry
was published in Encyclopedia of Spectroscopy & Spectrometry,
Mass Spectrometry, Academic Press, London, 1999, p.
1726.
One of the most interesting problems in the chemistry of organomercury
compounds is the existence of mercurinium ions. In some reactions
in the condensed phase these species are formed as intermediates.
We investigated structures of C2H4HgX+
ions (X=Cl, Br, I) using experimental mass spectral and theoretical
methods. C2H4HgX+
ions generated from neo-hexylmercury halides, ButCH2CH2HgX,
had an open-chain CH2CH2HgX+
structure. Fragmentation of molecular ions of isopropyl derivatives,
PriHgX, resulted in CH3CHHgX+
ions. n-Alkylmercurials most likely produced four-membered cyclic
XCH2CH2Hg
isomers rather than mercurinium ions. The results of the investigation
in the gas phase ion chemistry of mercury-containing species
and analytical aspects of mass spectrometry of mercury compounds
have been recently reviewed (Yu.S.Nekrasov, D.V.Zagorevski,
M.Sh.Mikeladze, Organometallic Chemistry in the USSR,
1992, 5, 237; D.V.Zagorevski, Yu.S.Nekrasov, Mass
Spectrom. Rev., 1995, 14, 21).
The chemistry of crown ether complexes with transition metal-containing
ions, especially those having their own ligands, was poorly known.
In our studies we used ion molecule reactions (IMR) to produce
such species in the gas phase. Our experimental results can be
generalized as follows: (i) IMR of transition metal-containing
ions, LnM+,
with crown ethers and related compounds are characterized by high
efficiency; (ii) adduct ion formation is the common process; (iii)
the ratio between adduct formation and ligand substitution is
determined by the ease of reduction of the metal atom; (iv) complexes
of "bare" transition metal ions with crown ethers can
be produced by ligand substitution reactions; (v) the presence
of mobile hydrogen atom(s) causes rearrangement with LH loss;
(vi) the ligand arrangement (steric effect) of the metal atom
rather than the cation affinity of the crown ether affects the
rate of replacement of one macrocyclic molecule by another. Dissociation
of ligated and "bare" transition metal ion-crown ether
complexes was studied. IMR were used to characterize metal-containing
ion structures and to identify crown ethers in complex synthetic
mixtures. The results are summarized in the review (D.V.Zagorevski,
Yu.S.Nekrasov, Org. Mass Spectrom., 1993, 28,
1562).
Neutralization-reionization mass spectrometry (NR MS) was applied
to identify structures of transition metal-containing ions and
to generate their neutral counterparts. Particular attention was
paid to the generation of previously unknown or elusive p-complexes
having a coordinative and electron rich metal atom. We successfully
used this method to produce 19-electron rhodocene and its monosubstituted
derivatives, odd-electron ferrocenes, C5H5FeC5H4=X.
(X=O, CH2, CO). Neutral zirconocene,
which has been proposed as a reaction intermediate in many catalytic
reactions, was generated by us as a monomeric species for the
first time. It was demonstrated that C10H10Ti+.
ions and their neutral counterparts existed as metal hydrides
rather than had metallocene structure. A number of novel derivatives
of low-valence transition and main group elements were generated
by using the NR MS method. The methodological and practical aspects
of neutralization-reionization mass spectrometry applied to coordination
and organometallic chemistry was the subject of several review
articles (D.V.Zagorevskii, J.L.Holmes, Mass Spectrom. Rev.,
1994, 13, 133; D.V.Zagorevskii, J.L.Holmes, Mass
Spectrom. Rev., 1998, 18, 87; D.V. Zagorevskii,
Coord. Chem. Rev., 2002, 224-225, 5).
A variety of tandem mass spectrometry methods were applied to
the search for a non-classical ethyl cation stabilized by organic
molecules. It was suggested that non-classical forms of C2H5X+Rn
ions were responsible for the observed hydrogen atom mixing within
ethyl group(s). We demonstrated that (C2H5)2Cl+ ions predominantly
existed in the non-classical form. The non-classical isomers of
(CH3)2C+OC2H5, C2H5I+CH3, (C2H5)2I+ and (C2H5)2Br+ were also identified,
but the majority of these ions contained classical ethyl groups.
No evidence was found for the non-classical isomers of protonated
ethylhalides and (C2H5)3O+ ions. A study of ethylated ketones
and aldehydes indicated that decreasing the proton affinity of
a carbonyl molecule resulted in a higher degree of the H/D-mixing.
Various ionization methods and tandem mass spectrometry techniques
were employed to generated protonated tirapazamine (SR4233) and
its metabolites and to study their reactivity. It was demonstrated
that the oxygen atom at the 4-N-atom was the exclusive site of
protonation of tirapazamine. Neutralization-reionization mass
spectrometry was used to generate stable in the gas phase neutral
counterpart of the protonated SR4233. This radical had been considered
as a key intermediate in the enzymatic transformation of the drug,
but it has never been detected before our experiments.
D. Zagorevskii, “Stereochemical aspects of organometallic
compounds by mass spectrometry”, in Encyclopedia of Mass
Spectrometry, Eds. N. Nibbering, M.L. Gross and R. Caprioli,
Pergamon Press, Oxford et al., 2004, V. 4,
Chapter G24.
D. Zagorevskii, “The generation of elusive metal complexes
by neutralization-reionization mass spectrometry (NRMS)”,
in Encyclopedia of Mass Spectrometry, Eds. N. Nibbering, M.L.
Gross and R. Caprioli, Pergamon Press, Oxford et al., 2004,
V. 4, Chapter G34.
D.V.Zagorevskii, “Mass Spectrometry” in Comprehensive
Coordination Chemistry (Ed., A.B.P. Lever), Elsevier, New York,
2003, Chapter 1.78.
D.V.Zagorevskii, “Neutralization-Reionization Mass Spectrometry”,
in Comprehensive Coordination Chemistry (Ed., A.B.P. Lever),
Elsevier, New York, 2003, Chapter 1.80.
Zagorevskii, D.; Song, M; Breneman, C.; Yuan, Y.; Fuchs, T;
Gates, K S.; Greenlief, C. M. “A mass spectrometry study
of tirapazamine and its metabolites insights into the mechanism
of metabolic transformations and the characterization of reaction
intermediates”. J. Am. Soc. Mass Spectrom., 2003,
14, 881-892.
D.V.Zagorevskii, "The Generation and Characterization
of Elusive Metal Complexes in the Gas Phase: Neutralization-Reionization
Mass Spectrometry and Related Experiments", Coordination
Chemistry Reviews, 2002, 225 (1-2), 5-34.
Zagorevskii D.V., Holmes J.L., "A Tandem Mass Spectrometry
Study of [C,H2,X2,Si]+.
Ions (X=H,D,Cl) and the Generation of Their Neutral Counterparts",
European Mass Spectrom., 2000, 6 (2), 89-96.
D.V.Zagorevskii, "Organometallics Studied Using Mass Spectrometry",
in: Encyclopedia of Spectroscopy & Spectrometry, Mass Spectrometry:
Applications. (Eds. J. Lindon, G. Tranter and J. Holmes), Academic
Press, London, 1999, 1726-1733.
D.V.Zagorevskii, "Neutralization-Reionization Mass Spectrometry
Applied to Organometallic and Coordination Chemistry (Update:
1994-1998)", Mass Spectrometry Reviews, 1999,
18 (2), 87-118.
Zagorevskii D.V., Holmes J.L., "False Recovery Signal in
Neutralization-Reionization Mass Spectra of Iodonium Ions".
European Mass Spectrom., 1997, 3 (4), 317-319.
Zagorevskii D.V., Holmes J.L., "The Generation and Identification
of Neutral CpFeC5H4=O
(X = O, CH2, CO) Complexes in
the Gas Phase by Tandem Mass Spectrometry", Organometallics,
1997, 16 (9), 1969-1973.
Zagorevskii D.V., Holmes J.L., Ross, C.W., III, "A Tandem
Mass Spectrometry and Fourier Transform-Ion Cyclotron Resonance
Study of Ionized Ethylated Acetone and Deuterated Analogues",
J. Am. Soc. Mass Spectrom., 1997, 8 (4),
327-336.
D.V.Zagorevskii, Yu.S.Nekrasov , "Mass Spectrometry of Organomercurials",
Mass Spectrometry Reviews, 1995, 14 (1),
21-48.
Zagorevskii D.V., Sirois M., Cao J.R., George M., Holmes J.L.,
Ross C.W., III, "Continuing the Search for a Non-Classical
Ethyl Cation Stabilized by Organic Molecules: The Triethyloxonium
Ion". J. Mass Spectrom., 1995, 31 (1),
55-61.
Zagorevskii D.V., Holmes J.L., "A Tandem Mass Spectrometry
Study of the Zirconocenium Ion; The Generation of Neutral Zirconocene
in the Gas Phase", Organometallics, 1995, 14
(11), 5041-5043.
D.V.Zagorevskii, J.L.Holmes, "Neutralization-Reionization
Mass Spectrometry Applied to Organometallic and Coordination Chemistry",
Mass Spectrometry Reviews, 1994, 13 (2),
133-154.
Yu.S.Nekrasov, D.V.Zagorevskii, "Mass Spectra of the Organometallic
Compounds of As, Sb and Bi". In: The Chemistry of arsenic,
antimony and bismuth compounds (Ed. S.Patai). John Wiley @ Sons
Ltd., Chichester et al., 1994, Chapter 6, p. 237-263.
Yu.S.Nekrasov, D.V.Zagorevskii, "Stereochemical effects
in the mass spectra of organometallic compounds". In: Applications
of Mass Spectrometry to Organic Stereochemistry. VHC Publishers.
1993, Ch. 22, p. 657-671.
Zagorevskii D.V., Holmes J.L., "The characterization of
titanocenium and titanocene by tandem mass spectrometry",
Org. Mass Spectrom., 1993, 28 (1), 49-55.
Zagorevskii D.V., Holmes J.L., "The observation of rhodocenium
and substituted rhodocenium ions and their neutral counterparts
by mass spectrometry", Organometallics, 1992,
11 (10), 3224-3227.
Complete
list of publications
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