In order to use sulfur-containing resources economically and with minimal environmental damage, it is important to understand the desulfurization processes. Hydrodesulfurization, for example, is carried out on the surface of a heterogeneous metal sulfide catalyst. Studies of simple, soluble inorganic systems provide information regarding the structure and reactivity of sulfur-containing compounds with metal complexes. Further, consistent with recent trends in materials chemistry, many model compounds warrant further study as catalyst precursors. The reactivity of low-valent organometallic sandwich pi-complexes toward dithiocarboxylic acids is described. For example, treatment of bisbenzene vanadium with CH3CSSH affords a divanadium tetrakis(dithioacetate) complex. The crystallographically determined V-V bond distance, 2.800(2), is nearly the same as the V-V bond distance in a V(mu-nu squared-S2)2V' unit in the mineral patonite (VS4)n. The stability of the V2S4 core in the dimer is demonstrated by evidence of V2S4(+) in the mass spectrum (70 eV, solid probe) of the vanadium dimer. Several other systems relevant to HDS catalysis are also discussed

Andras, Maria T.

Duraj, Stan A.

Hepp, Aloysius F.

English

NASA Technical Reports Server

NASA Technical Mem0randum 103666
Reactivity of _-Complexes of Ti,
Towards Dithioacetic Acid: Synthesis
and Structure of Novel Metal
Sulfur-c0ntaining complexes
v, and Nb
Stan A. Duraj and Maria T. Andras
Cleveland State University
Cleveland, Ohio
and
Aloysius F. Hepp
Lewis Research Center
Cleveland, Ohio _
i
Prepared for the
Fall Meeting of the Materials Research Society
Boston, Massachusetts, November 26--December 1, 1990
.... (NASA-TM-103665) REACTIVITY Of PT-COMPLEX_S N91-192_._ -_= --_zz.,_:_±:_
OF Ti, V, ANb Nb TOWAROS DITHTOAC'-TTC ACID:
SYNTHESIS AND STRUCTURE OF NOVEL METAL :
_._.__GULFUR-CONTAINING:: COMPLEXES (NASA) 6 p Unclas
CSCL 0TO G3/25 000107/
https://ntrs.nasa.gov/search.jsp?R=19910009943 2020-03-19T18:46:34+00:00Z

REACTIVITY OF x-COMPLEXES OF Ti, V, AND Nb TOWARDS DITHIOACETIC ACID:
SYNTHESIS AND STRUCTURE OF NOVEL METAL SULFUR-CONTAINING COMPLEXES
STAN A. DURAJ,* MARIA T. ANDRAS,* AND ALOYSIUS F. HEPP**
** Department of Chemistry, Cleveland State University, Cleveland, OH 44115
NASA Lewis Research Center, Mail Stop 302-I, Cleveland, OH 44135
INTRODUCTION
As the price of crude oil rises, the use of feedstocks with increased
levels of sulfur and metals will increase [I]. In order to use these
resources economically and with minimal environmental damage, it is important
to understand processes such as hydrodesulfurization (HDS) and
hydrodemetallation (HDM) catalysis [2]. A Co-promoted molybdenum sulfide
(Ni or W are sometimes substituted for Co and Mo) on q-alumina catalyst is
the industry standard for metal and sulfur removal under H2; HDM is often
part of the HDS process [3]. A periodic effect on the activity of metal
sulfides for HDS was demonstrated by Pecoraro and Chianelli [4]. Maximum
activity was observed for second- and third-row platinum group metal
sulfides: RuS2, OsS , Rh2S3, and IrS2 were shown to have 20 to 40 times the
activity of MoS 2 [41. Early transition metal sulfides, on the other hand,
have minimal HDS activity [4]; vanadium, for example, can actually inhibit
catalyticactivity [I].
The study of simple inorganic model systems can also enhance an
understanding of catalytic processes. Detailed knowledge of relevant systems
can be gained from structural and spectroscopic studies of sulfur-containing
metal compounds. A further.motivation for this chemistry is the possible
invention of novel precursors for solid state materials [5], with potentially
improved properties. In light of the above discussion and the biological
relevance of iron- and molybdenum-containing metal sulfur clusters [6J, it
is not surprising that many model system [7] and catalytic studies [8] focus
on the chemistry of compounds of group 6 through 12 metals. However, while
there is tremendous activity and interest in the chemistry of metal complexes
with sulfur-containing ligands [9-1111 this interest generally does not
extend to the electron deficient transition metals, particularly vanadium.
Since the vanadium content of some crude oils approaches 1000 ppm [I] it is
important to learn more about vanadium sulfur chemistry. Our interest in
early transition metal and sulfur chemistry [12] led us to explore the
reactivity of V, Nb, and Ti sandwich compounds with an organic sulfur source,
dithioacetic acid [13]. The following discusses some of our recent work as
it relates to desulfurization of dithioacetic acid and new preparative routes
to metal sulfide precursors.
EXPERIMENTAL
All manipulations of moisture and air-sensitive materials were done
under an inert atmosphere by standard Schlenk techniques on a double-
manifold vacuum line or in a Vacuum Atmospheres Co. glovebox equipped with
a HE-493 dri-train. Solvents were freshly distilled from benzophenone ketyl
prior to use. The metal sandwich compounds and CH3CSSH were synthesized as
described in [13]. NMR spectra were recorded on a Bruker AC3OOF or a Varian
FT-8OA. Infrared spectra were recorded on a Perkin-Elmer 599B
spectrophotometer. Electron impact mass spectra were recorded on a Finnigan
TSQ-45 mass spectrometer. All single-crystal x-ray analyses, except the
divanadium complex, were performed on an Enraf-Nonius CAD-4 diffractometer.
RESULTSANDDISCUSSION
[(_5-CsH5)Ti(77-C7HT)]5 reacts with excess CH3CSSH in toluene at 25°C for
3 days to produce [(7 -C5Hs)Ti(S2CCH3)3], I, in 83 _ yield. Gas
chromatography/ mass spectral (GC/MS) analysis of the reaction solution
showed the presence of 1,3,5-cycloheptatriene. Light yellow prismatic
crystals were7grown by layering a toluene solution of I with hexanes [14].
[(7 -C5H5)Nb(7 _C7H7)] reacts with excess CH3CSSH in diethyl ether for 4 days
to produce [(7_-C5Hs)Nb(S2CCH3)2(TL-S2)], 2, in 83 _ yield. GC/MS of the
reaction solution showed the presence of cycloheptetrienyl dimer. Red black
prismatic crystals were grown by layering a diethy] ether/toluene solution
of 2 with heptane [15]. (_b-C6H6)2V reacts with excess CH3CSSH in toluene
at 25°C for 4 days to produce [(CH3CS2)2V(_-TL-S2)2V(SzCCH3)2], 3, in yields
up to 62 _. Brown crystals were grown by layering a benzene solution of 3
with heptane [16]. (7 -C5H5)2V-reacts with excess CH3CSSH in THF-toluene at
250C for 4 days to produce [(7_-CBH5)4V4(#3-S)4)], 4, in yields up to 47 4.
Dark purple cubic crystals were grown by layering a toluene solution of 4
with heptane [17]. ORTEP structures of I, 2, 3 and 4 are shown in figure I.
C2
ClC5__c4C3
$2
,...h
Til _-_$3
_$5 C9
'C10
1
C9
2 c, _
5 VI '_'
1;7 C6
C8 C10
Figure I. ORTEP drawings of I, 2, 3, and 4 also define the labelling scheme.
The thermal ellipsoids enclose 504 of electron density.
Magnetic susceptibility, NMR and structural data are consistent with a
do electronic structure for I and 2. Both complexes have retained a
cyclopentadienyl ring in the coordination sphere. Several differences
between I and 2 are apparent when the two complexes are compared. Most
important is the side-on chelating disulfide that is formed in the course of
the synthesis of 2 but not in I. Both complexes have pentagonal bipyramidal
structure, but 2 is distorted by the small angle of S(5)-Nb-S(6) of 48° due
to the side-on bonding of the disulfide.
Complex I is the first examples of an organometallic Ti dithioacetate
complex; 2 is the first example of a Nb dithioacetate. Analysis of the
cycloheptatriene fragments imply that different mechanismsare operating for
Ti and Nbcomplex formation. An 77 _I isomerization followed by protonation
results in the formation of 1,3,5-cycloheptatriene; the dithioacetate
replacing the _I-CTH7 ligand to yield a Ti(IV) complex that cannot be
oxidized further after the tris dithioacetate is formed. The by-product
cycloheptatrienyl dimer in 2 implies that desulfurization promotes oxidation
of tetravalent Nb and rapid loss of C7H7, resulting in radical coupling. The
lack of any further reaction of Ti in I illustrates the lack of HDS activity
in group IV sulfides [I,4]: the stability of Ti(IV)-sulfur bonds.
Magnetic susceptibility and structural data is consistent with bonding
between vanadium atoms in both 3 and 4. In 3, a V-V distance of 2.800 A,
is consistent with a single bond; the compound is diamagnetic as expected for
a dl-dI unit. In 4, paramagnetism is consistent with four V(III) ions. The
V-V distance of 2.876 A and electron count imply a formal bond order of 2/3.
Both reactions resulted in desulfurization of dithioacetic acid, vanadocene
reacted to yield only partial desulfurization upon formation of 4.
As discussed above, the V-V bond distance in 3 is 2.800(2) A and is
nearly the same as the V-V bond distance in the tightly bound V(_-_2-S2)2 V'
unit (V-V distance of 2.83 A [18]) in the mineral patronite, (VS4_n and is
similar to a recently described V-V compound prepared from VS4J- and a
dithiuram disulfide derivative (V-V distance of 2.85 A [19]). The stability
of the V2S_ core in 3 is evidenced by the identification of V2S4 + in the mass
spectrum (70 eV, solid probe). The cubic unit in 4 represents the first
structure of the V parent compound in the cubic cyclopentadienyl-metal
sulfide cluster series .[11], the methyl-cyclopentadienyl complex being
previously characterized [20]. Finally, the difference in chemistry between
(_6-C6H6)2V and (_5-C5H5)2V illustrates the potential utility of V(O) starting
materials to explore new metal-sulfide chemistry; the chemistry of
cyclopentadienyl metal-sulfur compounds is well established [11].
CONCLUSIONS
We and others [13, 19, 20] have shown that the chemistry of early
transition metals is similar to that of later transition metals [7-11] in the
formation of sulfide metal complexes. While the strong metal-sulfur bond and
related electronic factors preclude useful HDS catalysis activity of early
transition metal sulfides, the fact that vanadium is present in relatively
high concentration in crude oil argues for the study of vanadium and
heteronuclear-vanadium sulfide systems. The vanadium dimer 3, represents an
easily-prepared model complex of a mineral of relevance to HDS catalysis.
The use of low-valent _-bonded sandwich compounds and dithiocarboxylic acids
as starting materials to prepare metal sulfur-containing complexes is novel
and shows the potential for the development of facile syntheses of new early
transition metal sulfide compounds. More importantly this chemistry may be
useful for producing mixed metal sulfide complexes, more likely to be useful
as models of or precursors to catalytic species [21]. We are currently
extending our work in this direction.
ACKNOWLEDGEMENTS
S.A.D. and M.T.A. acknowledge support from the Petroleum Research Fund,
a Research Creative Activity Award (Cleveland State University) and a
Research Challenge Grant (Ohio Board of Regents). S.A.D. acknowledges
partial support from NASA grant NCC 3-162. A.F.H. acknowledges support from
the Director's Discretionary Fund at NASA Lewis. We thank Dr. P. Kibala and
Prof. F.A. Cotton, Texas A&M University, for x-ray structural analysis of 3.
3
REFERENCES
[1] O. Weisser and S. Landa, Sulphide Catalysts, Their Properties and
Applications (Pergammon Press, New York, 1973).
[2] B.C. Gates, J.R. Katzer, G.C.A. Schuit, Chemistry of Catalytic Processes
(McGraw-Hill, New York, 1979).
[3] J. Wei, in Catalyst Design Progress and Perspectives, edited by L.L.
Hegedus (John Wiley and Sons, New York, 1987), pp. 245-272.
[4] T.A. Pecoraro and R.R. Chianelli, J. Catal. 67, 430 (1981); R.R.
Chianelli, Catal. Rev. - Sci. Eng. 26, 361 (1984_
[5] E. Ramli, T.B. Rauchfuss, and C.L. Stern, J. Am. Chem. Soc. 11___22,4043
(1990).
[6] F.A. Cotton and G. Wilkinson, Advanced Inorqanic Chemistry, 5th ed.
(John Wiley and Sons, New York, 1988), pg. 1335.
[7] A. M_ller, Polyhedron 5, 323 (1986).
[8] M. Rakowski DuBois, Chem. Rev. 8__2,1 (1989).
[9] M. Draganjac and T.B. Rauchfuss, Angew. Chem. Int. Ed. Eng. 24, 742
(1985).
[10] A. MUller and E. Diemann, Adv. Inorg. Chem. 31, 89 (1987).
[11] J. Wachter, Angew. Chem. Int. Ed. Eng. 2__88,1613 (1989).
[12] G.C. Campbell, J.A.M. Canich, F.A. Cotton, S.A. Duraj, and J.F. Haw,
Inorg. Chem. 2__55,287 (1986).
[13] S.A. Duraj, M.T. Andras, and B. Rihter, Polyhedron 8, 2763 (1989); S.A.
Duraj, M.T. Andras, and P.T. Kibala, Inorg. Chem. 2__99,1232 (1990); M.T.
Andras, Ph.D. Thesis, Cleveland State University, 1990.
[14] Crystal Structure Data for i: Space Group, Pcba; a : 16.964(5) A, b :
24.545(10) A, c = 7.832(2) A, Z = 8, and V = 3261(9) A3.
[15] Crystal Structure Data for 2: Space Group, P21/c; a = 13.365(2) A, b =
7.906(4) A, c = 13.710(2) A, # = 96.44(3)*, Z = 4, and V = 1440(i) A3.
[16] Crystal Structure Data for 3: Space Group, P21<c _ a = 10.425(2) A, =11.123(2) A, c = 9.133(4) A, # = 97.12(2)*, Z - , and V = 1051(I) _3.
[17] Crystal Structure Data for 4: Space Group, C2/c; a = 17.764(5) A, b =
8.119(2) A, c = 16.158(2) A, fl = I16.65(2)*, Z = 4, and V = 2083(2) A3.
[18] R. Allman, I. Baumann, A. Kutoglu, H. Rosch, and E. Hellner,
Naturwissenschaften 5__11,263 (1964).
[19] T.R. Halbert, L.L. Hutchings, R. Rhodes, and E.I. Stiefel, J. Am. Chem.
Soc. 108, 6437 (1986).
[20] C.M. Ballinger, T.B. Rauchfuss, and A.L. Rheingold, J. Am. Chem. Soc.
105, 6321 (1983).
[21] P. Li and M.D. Curtis, Inorg. Chem. 2_99,1242 (!990).
National Aeronautics and
Space Administration
1, Report No. 2. Government Accession No.
NASA TM- 103666
4. Title and Subtitle
Reactivity of r-Complexes of Ti, V, and Nb Towards Dithioacetic Acid:
Synthesis and Structure of Novel Metal Sulfur-Containing Complexes
Report Documentation Page
3. Recipient's Catalog No.
5. Report Date
6. Performing Organization Code
8. Performing Organization Report No.
E-5873
10. Work Unit No.
307-51-00
11. Contract or Grant No.
13. Type of Report and Period Covered
Technical Memorandum
14. Sponsoring Agency Code
7. Author(s)
Stan A. Duraj, Maria T. Andras, and Aloysius F. Hepp
9. Performing Organization Name and Address
National Aeronautics and Space Administration
Lewis Research Center
Cleveland, Ohio 44135-3191
12. Sponsoring Agency Name and Address
National Aeronautics and Space Administration
Washington, D.C. 20546-0001
15. Supplementary Notes
Prepared for the Fall Meeting of the Materials Research Society, Boston, Massachusetts, November 26--
December 1, 1990. Stan A. Duraj and Maria T. Andras, Cleveland State University, Cleveland, Ohio.
16. Abstract
In order to use sulfur-containing resources economically and with minimal environmental damage, it is important
to understand desulfurization processes. Hydrodesulfurization, for example, is carried out on the surface of a
heterogeneous metal sulfide catalyst. Studies of simple, soluble inorganic systems provide information regarding
the structure and reactivity of sulfur-containing compounds with metal complexes. Further, consistent with recent
trends in materials chemistry, many model compounds warrant further study as catalyst precursors. We describe
the reactivity of low-valent organometallic sandwich r-complexes towards dithiocarboxylic acids. For example,
treatment of bisbenzene vanadium with CH3CSSH affords a novel divanadium tetrakis(dithioacetate) complex. The
crystallographically determined V-V bond distance, 2.800(2), is nearly the same as the V-V bond distance in a
V(/z-_/2-S2)zV ' unit in the mineral patronite, (WS4) a. The stability of the V2S 4 core in the dimer is demonstrated
by evidence of V2S 4+ in the mass spectrum (70 eV, solid probe) of the vanadium dimer. Several other systems
relevant to HDS catalysis are also discussed.
17. Key Words (Suggested by Author(s))
Catalysts; Metal sulfides; Nb sandwich compounds;
V sandwich compounds; Organometallic sulfides
18. Distribution Statement
Unclassified - Unlimited
Subject Category 25
19. Security Classif. (of this report) 20. Security Ctassif. (of this page) 21. No. of pages
Unclassified Unclassified 5
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Reactivity of pi-complexes of Ti, V, and Nb towards dithioacetic acid: Synthesis and structure of novel metal sulfur-containing complexes

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