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Organometallic Titanium Complexes with Unpaired Electrons Syntheses and Structures of [{(5-Cp)2 TiF2}3 Ti] and [{(5-Cp)2 TiF2}3Al].

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5
4
used, as shown by the examples I b,d; second, by the degree
of alkylation at the C atom from which the acyl group shifts
to form ultimately 3, as shown by the comparison of 1 b/l c ;
third, the proximity of carbonyl C atom to the C = C bond
(particularly in 1 d,e) favors the formation of 3. This particular proximity of carbonyl C atom to the C = C bond in 1 d,e
gives rise to a bathochromic shift of the longest wave (nn*)
UV absorptions by 450-500 cm-’ with respect to those of
the corresponding hydrogenated ketones (for 1 a,b and 1 c a
much smaller shift is observed). It also appears to lead to a
large decrease in the energy of the lowest triplet state, as
shown by the efficient sensitization of the formation of 3d.e
by benzophenone (ET = 68.6); by contrast. for the formation of 3 b, benzonitrile (ET = 76.5) IS required.
The designation (in the title) “oxadi-n-ethane” rearrangement for the formation of 3 is derived from the analogy to
the “di-x-ethane”[141and the “oxadi-n-methane” (ODPM)
rearrangements. The latter rearrangement, which has been
known for a long
formally differs from the one
described herein only by the presence of a second saturated
C atom between the C = C and the C = O unit; as a result a 1,3
shift instead of a 1,2 shift of the acyl moiety occurs and a
cyclobutane ring closure instead of a cyclopropane ring closure takes place. To our knowledge, a non-allylic 1,3 shift of
the acyl moiety has not been observed so far. In addition to
the described similarity there is a clear analogy to the ODPM
rearrangement with regard to the dependence of the reactivity on the electronically excited state,“’] suggesting that the
two rearrangements have similar mechanisms. Thus, the
two-step mechanism formulated in Scheme 2, which uses 1 e
as an example, is assumed.
6
P
spin decouplings and NOE spectra. In these spectra all the resonance
signals (except the badly resolved ones of the central sections of the tetramethylene bridges) could be assigned unequivocally. In addition, the
molecular structure o f 3 e was confirmed by a single-crystal X-ray structure
analysis (1. Ortmann. C. Kruger, unpublished).
Unless otherwise stated all ETvalues are from’ S.L. Murov, Hundhook ig
Phi~rot/irnii.\rr?.Dekker. New York. 1973.
T. Ni. R. A. CaldweI1. L. A. Melton. J . Am. Ci7em. Sue. 1989, 111. 457
464, R. A. Caldwell. University of Texas. Dallas. private communication.
Acetophenone (ET =73.7) had no effect as sensitizer: acetone (as solvent.
ET =79-82) led to a complex mixture. containing no Z b and only a little
3b: instead it contained mainly products which seem to have resulted from
a hydrogen transfer from acetone to the excited C=C bond.
These reactions are apparently induced by a 6-H abstraction by the oxygen
atom of the excited carbonyl group. The resulting 1.5 diradical stabilizes
by fragmentation of a strained C-C bond to give a 1.3 diradicdl, which
reacts to give 4 and 5.
W. C. Schumann, D. B. Vashi. J. A. Robs. R. W. Binkley. J Org. Chmi.
L972. 37. 21 -24.
Reviews: D. 1. Schuster in ReorrungPnirnrs in Ground und E.~ciredS I U I ~ S ,
V d . 3 (Eds.: P. DeMayo), Academic Press. New York, 1980, pp. 232-279;
K. Schaffner. 7 h u h r d r o n 1976. .?2. 641 -653; K. N. Houk, Chrm. R ~ Y .
1976. 76. 1-74: see also: M. .I.C. M . Koppes. H. Cerfontain. Reel. Truv.
Chin!. P u j ~ - B i i s1988. 107, 549 562; T. J. Eckersley. N. A. J. Rogers, Ti.rrnhtcbon 1984, 40. 3759-3768. and references therein: D. E. Sadler, J.
Wendler. G. Olbrich. K. Schaffner, J. Ani. Chem Soc. 1984.106. 2064Phorochen~.
2071 : Review on synthetic applications- M. Demuth. 0,:~.
1991. I / . 37--109.
h
3[~e~*
I
Ph’
Organometallic Titanium Complexes with
Unpaired Electrons: Syntheses and Structures of
I((q5-Cp),TiF,),Ti] and [((q5-Cp’)2TiF2)3A1]**
By Feng-quan Liu, Heinz Gornitzka. Dietmar Stalke,
and Herbert W. Roesky*
Dedicated to Projessor Jean ‘ne M . Shreeve
an the occasion of’ her 60th birthday
The polynuclear titanium complexes previously
reported”’ all contain titanium in its highest oxidation
state. Well-known paramagnetic d ’ electron systems such
as [{Cp(C,H,)TiOH),][21 (Cp = q5-C,H,),
[{Cp,Ti(p-H),],AIC1],131 [{Cp,TiX},ZnX2][41 (X = CI, Br), or
[(Cp2TiCl},MnCl2]~
20C,H,‘51 are formed with a maximum of two titanium atoms. AH these complexes have 0x0,
hydrido, chloro, or bromo bridging ligands. Since fluorine
atoms have a marked tendency to form bridges, the syntheses of the corresponding fluorotitanium complexes should be
The reaction of [Cp,Ti(CO),][’l with [Cp,TiF,ll*] in a 1 : 1
ratio leads to the formation of the complexes 1 and
(Scheme I), as well as brown insoluble precipitate. Com-
3e
Scheme 2 .
Received: October 15. 1992 [Z5628IE]
German version. AnZen.. Chrm. 1993. 105, 436
[ I ] lc see ref. [S] le see ref. [2]. Id see ref. [3].
[2] J Leitich, 1. Heise. S. Werner. C. Kruger. K Schaffner, J Phorochern.
Phorohiol. A 1991, 57, 127-151
[ 3 ] P. E. Eaton, Acc. Chrm. Rec. 1968, 1 . 50-57.
[4] A. Pascual, N. Bischofberger, B. Frei. 0.Jeger, Hdv. Chin?.Acru 1988. 71.
374-388, and references therein; J. Berger, M. Yoshioka. M. P. Zink.
H. R. Wolf, 0. Jeger, ibiil. 1980. 63, 154-190, and references therein.
[5] R. R. Sauers. A. A. Hagedorn. S. D. van Arnum. R. P. Gomez, R. V.
Moquin. J. Orx. Chm?. 1987.52, 5501 -5505. and references therein; R. R.
Sauers, A. D. Rousseau, B. Byrne, J. Am. Chrrii. Soc. 1975,97,4947 4953,
and references therein.
[6] K . J. Crandall. J. P. Arrington. R. J. Watkins. J Chem. Sric. Chem. Con?mun. 1967. 1052.
171 H. Morrison, J An?. Chem. Soc. 1965. 87, 932.
181 R. R. Sauers. W. Schinski, M. M. Mason, 7i.rrohedron Lrrt. 1969, 79-82.
191 The molecular structures and the stereochemistry of all compounds were
derived from their 400MHz ‘ H and lOOMHz ”C NMR spectra (broad
band decoupling, DEPT sequence) including ‘3C/’H COSY. ‘HI’H spin-
Scheme 1. R
=
$-C,H,
1
\
R
2
~
442
f.: V C H Verla~s~esi~llschofi
n?hH, W-6940 Weinhrirn. 1993
[*] Prof. H. W. Roesky, Dr. F. Liu, Dip].-Chem. H. Gornitzka.
Dr. D. Stalke
lnstitut fur Anorganische Chemie der Universitit
Tammannstrasse 4. D-W-3400 Gottingen ( F R G )
[**I
This work was supported by the Deutsche Forschungsgemeinschaft, the
Volkswagenstiftung, and the Fonds der Chemischen Industrie. We would
like to thank D. F. Koch (Riedel-de-Haen. Seelze. FRG) for supplying the
perfluorinated polyethers for the crystal application.
0570-0833/93/0303-0442B 10.00+ , 2 5 4
An~ewC
. h m . I n ! . Ed. Engl. 1993, 32, No. 3
CplaJ
Fllal
Fllcl
v
File\
v
Fig. 1. Molecular structure of I . Selected distances [pm] and angles [ 1: Ti2-Tl
197.5(1). Ti1 -FI 209.4( 1). Til-Cp 204.4( 1 ); FI-Ti2-Fla 76.1 X(6). Ti2-Fl-Ti1
106.34(5). F l - T i l - F l a 71.15(6). Cp-Til-Cp(a) 135.8; the planes of the three
four-membered Ti,F, propeller blades intersect with an angle of 86.5 .
pound 1 crystallizes as blue crystals, whereas those of the
known complex 2 are green. The X-ray structure
reveals the characteristic structural feature of complex 1 ; a
distorted octahedral TiF, moiety a t the central Ti2 atom
(Fig. 1).
We replaced the central Ti atom with aluminum because
for the latter the formation of an octahedral AIF, group is
particularly favored. Indeed, [Cp,TiF,] o r [CpiTiF,]
(Cp' = $-C,H,Me) reacts with activated aluminum to give
the compounds 3 and 4, respectively (Scheme 2). The blue
R
\
/R
Ti
394
Scheme 2. 3: R
=
v*-C,H,: 4
R
= qS-C,H,Me
complex 3 is slightly soluble in T H F and toluene, and as
expected 4 is more soluble in these solvents.
The structure of 4 was determined by X-ray structure analysis (Fig. 2) and found to be isostructural with that of 1. The
four-membered Ti,F, (1) and AITiF, (4) rings in the two
structures are unsymmetrical [I : Ti2-FI 197.5(1), Ti-Fl
209.4(1) and 4: All-F1 181.2(2), Til-F1 209.5(2) pm]; the
octahedral coordination of the central atoms Ti2 and All,
respectively is significantly distorted, and they are surrounded by the four-membered rings (Ti,F, and AITiF,) in a propeller-like manner. The "propeller blade angle" between the
planes of the four-membered rings is 86.5" in 1 and 86.9" in
4. Because of the distortion of these rings [ l : F1-Ti2-Fla
76.18(6)0 and Ti2-Fl-Ti1 106.34(5)'; 4 Fl-All-Fla
80.91(?0>0 and All-FI-Ti1 105.40(8)"] a metal-metal bonding interaction can be excluded ( 1 ; Ti1 ... Ti2 325.77(10); 4:
All ... Ti1 31 1.3(2) pm). A comparable nonbonding Ti ... Ti
distance of 319.5(4) pm was found in [{Cp(C,H,)TiOH},].[2. l o ] A similar coordination to the aluminum atom
in 4 was found in [{(Me,Si),N),AI(NH,),J,Al].llll
The ESR spectra of the complexes 1 and 4 confirm the
paramagnetic behavior. In toluene a very broad resonance
signal is observed for each compound;" 21 similar observations were made for [{Cp,TiC1,},Zn].[41 Although.
organometallic titanium and zirconium compounds, in combination with aluminum compounds, are mainly used as catalysts in the polymerization of olefins, very little is known to
date about their interaction^.^'^.'^^ Compounds 1, 3. and 4
are interesting examples of the symbiosis of classical Werner
coordination and organometallic chemistry.
Experimental Procedure
1 : A mixture of [Cp,Ti(CO),] (0.35 g. 1.5 mmol) and [Cp,TiFJ (0.33 g.
1.5 mmol) in T H F (SO mL) was stirred for 24 h at rooin temperature and 6 h at
70 "C. The solution turned green. After removal of the solvent and the volatile
reaction products under vacuum the residue was crystallized from il hexane,
T H F ( 1 : l ) mixture. A brown amorphous solid remained. Blue crystals of I
(0.11 g. 0.14 mmol) formed from the solution and subsequently green crystals
of 2 [9] (0.23 g, 0.58 mmol). 1: M.p. > 310-C (decomp). MS(E1) mi; 197
(Cp,TiF) biggest fragment; IR (Nujol) i.[cm-l] = 3108. 1024m. 1012m. 804s.
498s. 405s; correct elemental analysis of C,,,H,,F,Ti4 . C,H,O (768.2).
2 : M.p. > 228 T(decomp) MS(E1) mi; 216 (Cp,TiF,). 197 (Cp,TiF). 1R (Nujol): ?[cm-'] = 3091m. 1093m. 793st. 471s: weak bands are not reported.
3: A solution of [Cp,TiF,] (0.43 g, 2 mmol) in T H F (SO mL) was added to A1
(0.2 g) and stirred for 40 h at room temperature. A green solution and a blue
solid were formed. The solution was filtered and the solid was extracted with
toluene (SO mL). Yield of 3 0.25 g (55%). M.p. > 320'C (decomp) I R (Nujol)
P[cm-l] = 3100m. 1017m. 800s, 617m. 552m, 397m; correct elemental analysis
for C,,H,,AIF,Ti, (675.2).
4: [CpiTiF,] (0.5 g, 2 mmol) was dissolved in T H F (SO mL) and treated with
aluminum (0.1 g). The mixture was stirred for 2 d a t room temperature, during
which time the solution turned dark green. After the solution had been filtered
the solvent was removed under vacuum. The residue was crystallized from
hexane/THF (1 : l ) ; yield of 4 0.35 g (70%). M.p. > 172'C (decomp), IR (Nujol): ;[ern-'] = 31 19m, 1498m, 1353m. 1027m. 899m, 861m. 814m. 789m. 582s.
541m. 446s. 405m; correct elemental analysis for C,,H,,AIF,Ti, (759.3).
Received: September 19,1992 [Z 5583 IE]
German version: Angeii. Chrm. 1993. 105. 447
Cp'iaJ
Fig. 2. Molecular structure of 4. Selected distances [pm] and angles [;I: All-F1
181.2(2). Fil-Fl ?09.5(2). Til-Cp 204.2(1), FI-All-Fla 80.91(10), All-Fl-Ti1
105.40(8). F l - T i l - F l a 68.29(9). Cp-TiI-Cp(a) 134.3; the planes of the three
four-membered AITiF, propeller blades intersect with a n angle of 86.9'.
Angew. Chcm. Inr. Ed. Engl. 1993, 32,
No. 3
(3 VCH Verlugsgesel1,schuftmhH,
[I] Gmelin Handhook of Inorgunic Chemistry, Organotitanium Compounds,
part 1-S, Springer, Berlin, 1977- 1990; Comprehensive Orgunomctaliic
Chrmi,ytry, Vol. 3 (Eds.: G. Wilkinson. F. G. A. Stone. E. W. Abel).
Pergdmon, Oxford, 1982.
[2] L. J. Guggenberger, E N . Tebbe, J Am. Chem. Sor. 1976. 98. 4137.
[3] A. I. Sizov, I. V. Molodniskaya, B. M. Bulychev, E. V. Evdokimovd. G. L.
Soloveichik, A. I. Guser. E. B. Chuklanova. V. I. Adrianov. J. Orgunornet.
Chem. 1987.335, 323.
[4] D. Gourier, D. Vivien. E. Samuel. J. Am. Chem. Soc. 1985, 107, 7418.
[5] D. Sekutowski, R. Jungst, G. D. Stucky, Inorg. Chrm. 1978. 17. 1848.
[6] M. Witt, H. W. Roesky, frog. lnorg. Chem. 1992, 40, 353.
[7] B. Demerseman, G. Bouquet, M. Biqorgne, J. Orgunomct. Chr,m. 1975,
101, C24.
[8] P. M. Druce. B. M. Kingston, M. F. Lappert, T. R. Spalding. R . C. Srivastava. J. Cham. Sor. A 1969, 2106.
W-6940 Weinheim, 1993
0570-0833/93/0303-0443$ iO.OO+ ,2510
443
[9] R. S. P. Coutts. P. C. Wailes. R. L. Martin, J. Orgunomer. Chem. 1973, 47,
375. [Cp,TiF], was prepared by the reduction of [Cp,TiF,] with aluminum.
[lo] Crystal Data: 1 crystallized with one molecule T H F : C,,H,,F,Ti,.
C,H,O, M = 768.3, rhombohedral. space group R%, u = b = 16.174(2),
c = 21.371(5)
V = 4841.6 A’, 2 = 6; pca,cd
= 1 581 Mgm-’, F(000) =
2352, X=0.71073.&, T = 1 5 3 K , p ( M o K , ) = 1 . 0 2 m m ~ ’ .Data were collected on a Stoe-Siemens-AED diffractometer. Intensities of a rapidly
cooled crystal (dimensions 0.3 x 0.4 x 0.3 mm) in an oil drop were collected
by the 2Oiw method in the range 8 - 5 2 0 5 55 Of the 4551 collected
reflections 1245 were independent and corrected for absorption and 1049
observed with Fo > 4u(Fu). 118 parameters were refined on F 2 with all
data (SHELXL-92) [15]. Largest difference maximum and minimum: 0.29
and - 0 . 2 6 e k 3 , respectively, R1 = 0.029 and wR2 = 0.080 (all data).
4: C,,H,,AIF,Ti,.
M =759.3, rhombohedra], space group R%, u = h =
16.549(5),
c=20.912(11)&
V=4959.9A3,
Z=6:
pCrlcd=
1.525 Mgm-’, F(OO0) = 2346. i.= 0.71073
T = 1 5 3 K. ~(Mo,,) =
0.79 mm- data were collected on a Stoe-Siemens-AED diffractometer.
Intensities of a rapidly cooled crystal (dimensions 0.4 x 0.4 x 0.3 mm) in an
A,
~
’.
A.
[I 11
[12]
[13]
[14]
[15]
[16]
oil drop were collected by the 2 Bio method in the range of 8 ’ I 2 0 I
45”.
Of a total of 1415 reflections 725 were independent and corrected for
absorption and 594 were observed with Fo > 4u(F0). 72 parameters were
refined on F’ with all data (SHELXL-92) [15]. Largest difference maximum and minimum: 0.22 and -0.50 e k 3 , respectively, R1 = 0.033 and
nR2 = 0.90 (all data). Both structures were solved with direct methods
(SHELXS-90) [16] and refined by full-matr~x least-squares of F 2
(SHELXL-90) [15]. Further details of the crystal structure investigations
are available on request from the Director of the Cambridge Crystallographic Data Centre, 12 Union Road, GB-Cambridge CB2 1 EZ (UK). o n
quoting the full journal citation.
K. J. L. Paciorek. J. H. Nakahara, L. A. Hoferkamp. C. George, J. L. Flippen-Anderson. R. Gilardi. W. R. Schmidt, Chcm. M a [ . 1991, 3, 82.
Examinations carried out by Dr. Marsh, Max-Planck-Institut, Gottingen.
H. Sinn, W. Kamiusky. Adv. Orgunomet. Chem. 1980. I R , 99.
W. Kaminsky. K. Kiilper. H. H. Brintzinger. F, R. W. P. Wild, A n g m .
Chcm. 1985. 97, 507: Angew. Chem. Inr. Ed. Engl. 1985, 24. 507.
G. M. Sheldrick, Universitit Gottingen 1992.
G. M. Sheldrick, Acru Crystullogr. 1990. A46, 467.
BOOKS
Book Reviews
Following the Trail of Light: A Scientific Odyssey. (Series:
Profiles, Pathways, and Dreams. Series editor: J. I. Seeman.) By M . Calvin. American Chemical Society, Washington, DC, 1992. XXIII, 175 pp., hardcover $24.95.ISBN 0-8412-1828-5
As a young assistant professor enamoured of coordination chemistry, I had occasion to refer frequently to Professor Calvin’s 1952 monograph Chemistry ofthe Metal Chelate
Compounds (coauthored with Arthur E. Martell). Therefore
I regarded Calvin as an inorganic chemist. When he was
awarded the 1961 Nobel Prize in chemistry “for his research
on the carbon dioxide assimilation in plants”, I began to
think of him as an organic chemist. After reading his latest
book, I have come to realize that this multidisciplinary scientist defies categorization. In explaining the book’s title, “Following the Light”, he states “The word ‘light’ was not meant
in its literal sense, but in the sense of following an intellectual
concept o r idea to where it might lead” (p. 134). In promoting this goal, he assembled in his laboratory “scientists
444
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whose disciplines ranged from psychology to botany, from
organic photochemistry to chemical evolution” (p.xxii).
Born on April 8, 1911 in St. Paul, Minnesota of emigrant
parents (father from Lithuania; mother from Russian Georgia) of limited financial means, Calvin showed an early interest in science, dismantling his toys and reassembling them
after understanding how they worked. The family moved to
Detroit, Michigan, where he attended high school. With the
aid of a scholarship he attended the Michigan College of
Mining and Technology (now Michigan Technological University) but interrupted his studies there for a year to earn
money as an analyst in a brass factory to continue his education. After receiving his B. S. degree in chemistry (1931) he
worked on the electron affinity of halogen atoms under
George C. Glockler at the University of Minnesota, from
which he received his Ph.D. degree (1935). He spent the
academic years 1935- 1937 at the University of Manchester
in England, where he worked on coordination catalysis, activation of molecular hydrogen, and metalloporphyrins with
chemist, political scientist, economist, and philosopher
Michael Polanyi, who introduced him to the advantages of
the interdisciplinary approach to science that was to chardcterize Calvin’s scientific career. In 1937, at the invitation of
Gilbert Newton Lewis, whose intuitive approach to science
also exerted a great influence on him, Calvin became an
Instructor at the University of California, Berkeley, the first
chemist not a U C graduate to be hired since 1912. He has
remained at Berkeley ever since and is now University Professor of Chemistry.
Calvin’s collaboration with G . E. K. (“Gerry”) Branch
resulted in the publication of The Theory oforganic Chemistry (1941), the first book on the subject written in the United States to employ quantum mechanics. Its publication
marked the advent of theoretical organic chemistry in the
United States and made Berkeley one of its foremost centers.
The World War I1 years saw his work on the use of cobalt
complexes that reversibly bond with molecular oxygen applied to an oxygen-generating machine for destroyers o r submarines. He also became involved in the Manhattan Project,
applying his expertise in chelation and solvent extraction to
the problems of decontaminating (purifying) the irradiated
uranium in fission products and isolating and purifying plu-
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