Monoazadiene complexes of early transition metals. 2. Syntheses and structures of titanium 1-aza-1,3-diene complexes and their reactions with ketones

Article abstract of DOI:10.1021/om970640j

The novel dark green or violet and air-sensitive 1-aza-1,3-diene titanocene complexes Cp₂-Ti[N(R¹)CH=C(R²)CH(Ph)] [R¹ = t-Bu, R² = H (7a); R¹ = C₆H₄-4-Me, R² = H (7b); R¹ = c-C₆H₁₁, R² = Me (7c)] were prepared by the complexation of the 1-aza-1,3-dienes 1a-c to the titanocene Cp₂Ti generated in situ by reduction of Cp₂TiCl₂ with magnesium. The solid-state structure of 7c shows a bent azatitanacyclic ring with a fold angle of 130.9(4)°. A series of electron-deficient 14e 1-aza-1,3-diene titanium complexes CpTi[N(R¹)CH=C(Me)-CH(Ph)]Cl [R¹ = c-C₆H₁₁ (8a), t-Bu (8b), C₆H₄-2-Me (8c), C₆H₄-4-Me (8d)] has also been prepared by reduction of CpTiCl₃ with magnesium in the presence of the 1-aza-1,3-dienes R¹N=CHC(Me)=CH(Ph) 1c-f. These new complexes were isolated as air-sensitive brown (8a,b) or dark red (8c,d) crystals in 50-65% yield. The X-ray crystal structure of 8c revealed that the coordination geometry for the 1-aza-1,3-diene ligands has substantial σ²,π-η⁴-metallacyclopent-4-ene character. The 1-aza-1,3-diene complexes 8a,c,d only exhibit supine geometry as confirmed by ¹H NMR spectroscopy, while 8b exists in both the conventional supine geometry and the prone geometry, which is demonstrated by quite different ¹H NMR chemical shift values. Addition of 8c to 1 equiv of acetophenone gives the seven-membered metallacyclic ring system CpTi[N(C₆H₄-4-Me)CH=C(Me)CH(Ph)C(Me)PhO] (9), whose structure has also been characterized by NMR spectral data and by X-ray diffraction analysis. In contrast to 8c, the 1-aza-1,3-diene titanocene complex Cp₂Ti[N(C-C₆H₁₁)CH=C(Me)CH-(Ph)] (7c) does not react with acetophenone even at high temperatures. ? MAD is used as an acronym for 1-aza-1,3-dienes (monoazadienes) in general. In this paper we will use MAD when N-alkyl-(￡)-cinnamaldimines (R¹)N=CHC(R₂)=CH(Ph) (R¹ = t-Bu, C-C₆H₁₁; R² = H, Me) or N-aryl-(E)-cinnamaldimines (R¹ = C₆H₄-2-Me, C₆H₄-4-Me; R² = H, Me) are meant.

Full text of DOI:10.1021/om970640j

2876
Organometallics 1998, 17, 2876-2884
Mon oa za d ien e Com p lexes of Ea r ly Tr a n sition Meta ls. 2.1
Syn th eses a n d Str u ctu r es of Tita n iu m 1-Aza -1,3-d ien e
Com p lexes a n d Th eir Rea ction s w ith Keton es†
J oachim Scholz* and Steffen Kahlert
Institut fu¨r Anorganische Chemie der Martin-Luther-Universita¨t Halle-Wittenberg,
Geusaer Strasse, D-06217 Merseburg, Germany
Helmar Go¨rls
Institut fu¨r Anorganische und Analytische Chemie der Friedrich-Schiller-Universita¨t J ena,
August-Bebel-Strasse 2, D-07743 J ena, Germany
Received J uly 28, 1997
The novel dark green or violet and air-sensitive 1-aza-1,3-diene titanocene complexes Cp2-
Ti[N(R1)CHdC(R2)CH(Ph)] [R1 ) t-Bu, R2 ) H (7a ); R1 ) C6H4-4-Me, R2 ) H (7b); R1 )
c-C6H11, R2 ) Me (7c)] were prepared by the complexation of the 1-aza-1,3-dienes 1a -c to
the titanocene “Cp2Ti” generated in situ by reduction of Cp2TiCl2 with magnesium. The
solid-state structure of 7c shows a bent azatitanacyclic ring with a fold angle of 130.9(4)°.
A series of electron-deficient 14e 1-aza-1,3-diene titanium complexes CpTi[N(R1)CHdC(Me)-
CH(Ph)]Cl [R1 ) c-C6H11 (8a ), t-Bu (8b), C6H4-2-Me (8c), C6H4-4-Me (8d )] has also been
prepared by reduction of CpTiCl3 with magnesium in the presence of the 1-aza-1,3-dienes
R1NdCHC(Me)dCH(Ph) 1c-f. These new complexes were isolated as air-sensitive brown
(8a ,b) or dark red (8c,d ) crystals in 50-65% yield. The X-ray crystal structure of 8c revealed
that the coordination geometry for the 1-aza-1,3-diene ligands has substantial σ2,π-η4-
metallacyclopent-4-ene character. The 1-aza-1,3-diene complexes 8a ,c,d only exhibit supine
1
geometry as confirmed by H NMR spectroscopy, while 8b exists in both the conventional
1
supine geometry and the prone geometry, which is demonstrated by quite different H NMR
chemical shift values. Addition of 8c to 1 equiv of acetophenone gives the seven-membered
metallacyclic ring system CpTi[N(C6H4-4-Me)CHdC(Me)CH(Ph)C(Me)PhO] (9), whose
structure has also been characterized by NMR spectral data and by X-ray diffraction analysis.
In contrast to 8c, the 1-aza-1,3-diene titanocene complex Cp2Ti[N(c-C6H11)CHdC(Me)CH-
(Ph)] (7c) does not react with acetophenone even at high temperatures.
In tr od u ction
In the course of our research directed toward the
reactivity of metal-coordinated heterodienes, we recently
reported the syntheses and the first structural study of
1-aza-1,3-diene zirconocene complexes Cp2Zr[N(R1)CHd
C(R2)CH(Ph)] (2) (R1 ) C6H4-2-Me, C6H4-4-Me; R2 ) H,
Me).1 Complexes 2 are available as air- and moisture-
The metal-promoted coupling of unsaturated organic
substrates constitutes a powerful strategy for carbon-
carbon bond formations in organic synthesis.2 Among
the reductants employed for such reactions are several
group 4 early transition metal-diene complexes. These
complexes have received considerable current attention
because of their unique M-C bonding properties and
their high reactivity toward a broad range of electro-
philes and unsaturated hydrocarbons.3 Thus, several
groups have described many examples where diene com-
plexes react with 1 or 2 equiv of an organic carbonyl
reagent to form seven- or nine-membered metalla-
cycles.4
(3) (a) Negishi, E.; Takahashi, T. Aldrichim. Acta 1985, 18, 31. (b)
Yasuda, H.; Tatsumi, K.; Nakamura, A. Acc. Chem. Res. 1985, 18, 120.
(c) Akita, M.; Matsuoka, K.; Asami, K.; Yasuda, H.; Nakamura, A. J .
Organomet. Chem. 1987, 327, 193. (d) Yasuda, H.; Nakamura, A.
Angew. Chem. 1987, 99, 745; Angew. Chem., Int. Ed. Engl. 1987, 26,
723. (e) Negishi, E.; Takahashi, T. Synthesis 1988, 1. (f) Buchwald, S.
L.; Nielsen, R. B. Chem. Rev. 1988, 88, 1047. (g) Dang, Y.; Geise, J . H.
J . Organomet. Chem. 1991, 405, 1. (h) Duthaler, R. O.; Hafner, A.
Chem. Rev. 1992, 92, 807. (i) Erker, G. Pure Appl. Chem. 1992, 64,
393. (j) Erker, G.; Berlekamp, M.; Lopez, L.; Grehl, M.; Scho¨necker,
B.; Krieg, R. Synthesis 1994, 212.
(4) Seven-membered metallacycles: (a) Yasuda, H.; Kajihara, Y.;
Mashima, K.; Nagasuna, K.; Nakamura, A. Chem. Lett. 1981, 671. (b)
Kai, Y.; Kanehisa, N.; Miki, K.; Akita, M.; Yasuda, H.; Nakamura, A.
Bull. Chem. Soc. J pn. 1983, 56, 3735. (c) Erker, G.; Dorf, U. Angew.
Chem. 1983, 95, 800; Angew. Chem., Int. Ed. Engl. 1983, 22, 777;
Angew. Chem. Suppl. 1983, 1120. (d) Erker, G.; Engel, K.; Atwood, J .
L.; Hunter, W. E. Angew. Chem. 1983, 95, 506; Angew. Chem., Int.
Ed. Engl. 1983, 22, 494. Nine-membered metallacycles: (e) Ausema,
J . B.; Hessen, B.; Teuben, J . H. Recl. Trav. Chim. Pays-Bas. 1987, 106,
465. (f) Yasuda, H.; Okamoto, T.; Matsuoka, Y.; Nakamura, A.; Kai,
Y.; Kanehisa, N.; Kasai, N. Organometallics 1989, 8, 1139. (g) Noe,
R.; Wingbermu¨hle, D.; Erker, G.; Kru¨ger, C.; Bruckmann, J . Organo-
metallics 1993, 12, 4993.
† MAD is used as an acronym for 1-aza-1,3-dienes (monoazadienes)
in general. In this paper we will use MAD when N-alkyl-(E)-cinna-
maldimines (R1)NdCHC(R2)dCH(Ph) (R1 ) t-Bu, c-C6H11; R2 ) H, Me)
or N-aryl-(E)-cinnamaldimines (R1 ) C6H4-2-Me, C6H4-4-Me; R2 ) H,
Me) are meant.
(1) (a) Part 1: Scholz, J .; Nolte, M.; Kru¨ger, C. Chem. Ber. 1993,
126, 803. (b) Part 3: Kahlert, S.; Go¨rls, H.; Scholz, J . Angew. Chem.,
in press.
(2) (a) Seebach, D. Angew. Chem. 1990, 102, 1363; Angew. Chem.,
Int. Ed. Engl. 1990, 29, 1320. (b) Organometallics in Organic Synthesis;
de Meijere, A., tom Dieck, H., Eds.; Springer-Verlag: Berlin, 1987. (c)
Organometallics in Organic Synthesis 2; Werner, H., Erker, G., Eds.;
Springer-Verlag: Berlin, 1989.
S0276-7333(97)00640-7 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 06/05/1998

Titanium 1-Aza-1,3-diene Complexes
Organometallics, Vol. 17, No. 13, 1998 2877
Sch em e 1
Sch em e 2
diene titanium chemistry. To obtain further insight into
the titanium 1-aza-1,3-diene chemistry, we have also
explored a series of novel 1-aza-1,3-diene titanium
complexes of the type CpTi(MAD)Cl. In this paper, we
report for the first time the syntheses and characteriza-
tion of some examples of this interesting class of
heterodiene compounds, including the molecular struc-
tures of a 1-aza-1,3-diene CpTiIV and a 1-aza-1,3-diene
Cp2TiIV complex.
Resu lts a n d Discu ssion
Tita n ocen e 1-Aza -1,3-d ien e Com p lexes. The pre-
parative procedure for the novel 1-aza-1,3-diene ti-
tanocene complexes Cp2Ti[N(R1)CHdC(R2)CH(Ph)] [R1
) t-Bu, R2 ) H (7a ); R1 ) C6H4-4-Me, R2 ) H (7b); R1
) c-C6H11, R2 ) Me (7c)] was analogous to that of the
zirconium derivatives 2 (Scheme 2).1a,8 Thus, addition
of magnesium turnings to an equimolar mixture of Cp2-
TiCl2 and the appropriate 1-aza-1,3-diene (R1)NdCHC-
(R2)dCH(Ph) [R1 ) t-Bu, R2 ) H (1a ); R1 ) C6H4-4-Me,
R2 ) H (1b); R1 ) c-C6H11, R2 ) Me (1c)] dissolved in
THF resulted in the formation of a dark solution.
Removal of the solvent in vacuo and extraction of the
product into diethyl ether followed by cooling to -20
°C allowed the isolation of 7a -c as air- and moisture-
sensitive violet (7a ) or dark green crystals (7b,c) in 60-
70% yield. The EI mass spectra of 7a -c clearly confirm
their monomeric nature, and the chemical characteriza-
tion supports the proposed constitution.
sensitive orange crystals in ca. 60-70% yield, when Cp2-
ZrCl2 is reduced with magnesium in the presence of
1-aza-1,3-dienes 1 (Scheme 1).
Two different synthetic methods have been explored
in attempts to find another preparative route to the
zirconocene 1-aza-1,3-diene complexes.5 Thus, the zir-
conocene equivalent Cp2Zr(1-butene), 3, prepared from
Cp2ZrCl2 and 2 equiv of n-butyllithium6 undergoes a
clean ligand exchange with 1-aza-1,3-dienes to form 2
(R1 ) t-Bu, CH2Ph, Ph; R2 ) H, R3 ) Me, Ph). A second
route to these 1-aza-1,3-diene complexes is based upon
the observation that 2 is formed by rearrangement of
an η2-imine zirconocene complex. The required (η2-
imine)zirconium complex 5 (R1 ) SiMe3, Ph; R2 ) R3 )
H) can be generated by C-H activation and loss of
methane from the methylzirconocene amide 4 (Scheme
1).7
At higher temperatures, the 1-aza-1,3-diene zir-
conocene complexes 2 (R1 ) C6H4-2-Me, R2 ) Me) react
with 1 equiv of acetophenone, forming only a single
isomer of the new azoxazirconacyclic metallocene com-
pound Cp2Zr[N(R1)CHdC(R2)CH(Ph)CMe(Ph)O] (6).1a
The potential use of 1-aza-1,3-diene zirconocene com-
plexes in other selective carbometalation reactions,
together with the total absence of related 1-aza-1,3-
diene titanocene derivatives in the literature, has
prompted us to initiate a study of the related 1-aza-1,3-
1
The H NMR spectra of 7a -c are similar to those of
the 1-aza-1,3-diene zirconocene compounds1 with two
resonances in a 1:1 ratio at δ 5.68 and 5.00 (7a ) and δ
5.74 and 5.18 (7b), as well as at δ 5.55 and 5.04 (7c) for
the diastereotopic Cp groups. In addition, characteristic
resonances due to the 1-aza-1,3-diene ligand are ob-
served. Particularly the signal of the terminal hydrogen
atom showing a significant upfield shift [δ 1.18 (7a ), 1.67
(8) Stabilization of “Cp2Ti” generated in situ by reduction of Cp2-
TiCl2 with magnesium has been reported. (a) Review: Pez, G. P.; Amor,
J . N. Adv. Organomet. Chem. 1981, 19, 1. Cp2Ti(CO)2: (b) Sikora, D.
J .; Moriarty, K. J .; Rausch, M. D. Inorg. Synth. 1986, 24, 147. Cp2Ti-
(PMe3)2: (c) Stephan, D. W. Organometallics 1992, 11, 996. (d) Kool,
L. B.; Rausch, M. D.; Alt, H. G.; Herberhold, M.; Honold, B.; Thewalt,
U. J . Organomet. Chem. 1987, 320, 37. (e) Kool, L. B.; Rausch, M. D.;
Alt, H. G.; Herberhold, M.; Thewalt, U.; Wolf, B. Angew. Chem. 1985,
97, 425; Angew. Chem., Int. Ed. Engl. 1985, 24, 394. Cp2Ti(CNC6H3-
Me2)2: (f) Kool, L. B.; Rausch, M. D.; Alt, H. G.; Engelhardt, H. E.;
Herberhold, M. J . Organomet. Chem. 1986, 317, C38. Cp2Ti(PhCt
CPh): (g) Shur, V. B.; Burlakov, V. V.; Volpin, M. E. J . Organomet.
Chem. 1988, 347, 77. (h) Shur, V. B.; Bernadyuk, S. Z.; Bulakov, V.
V.; Andrianov, V. G.; Yanovsky, A. I.; Struchkov, Y. T.; Volpin, M. E.
J . Organomet. Chem. 1983, 243, 157.
(5) Davis, J . M.; Whitby, R. J .; J axa-Chamiec, A. J . Chem. Soc.,
Chem. Commun. 1991, 1743.
(6) Negishi, E.; Holmes, S. J .; Tour, J . M.; Miller, J . A.; Cederbaum,
F. E.; Swanson, D. R.; Takahashi, T. J . Am. Chem. Soc. 1989, 111,
3336.
(7) (a) Buchwald, S. L.; Wannamaker, M. W.; Watson, B. T. J . Am.
Chem. Soc. 1989, 111, 776. (b) Buchwald, S. L.; Wannamaker, M. W.;
Watson, B. T.; Dewan, J . C. J . Am. Chem. Soc. 1989, 111, 4486. (c)
Coles, N.; Whitby, R. J .; Blagg, J . Synlett 1990, 271. (d) Synlett 1992,
143.

2878 Organometallics, Vol. 17, No. 13, 1998
Scholz et al.
Ta ble 1. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for Cp 2Ti[N(c-C6H11)CHdC(Me)CH(P h )] (7c)
Bond Lengths
Ti-N
Ti-C3
C1-N
2.016(3)
2.278(4)
1.354(5)
Ti-C1
C1-C2
Ti-H3
2.660(7)
1.375(6)
2.38(3)
Ti-C2
C2-C3
2.715(9)
1.446(6)
Angles
102.5(3) C3-Ti-N
Ti-N-C1
80.3(1) Ti-C3-C2 90.8(2)
C1-C2-C3 118.6(4) C2-C1-N 120.3(4) Ti-C1-H3 85.5(3)
(Ti,N,C3)-(C1,C2,C3,N)
130.9(4)
N-C1-C2-C3 and the N-Ti-C3 planes (130.9°) is
remarkably large compared with that (122.4°) for the
zirconocene complex Cp2Zr[N(C6H4-2-Me)CHdC(Me)-
CH(Ph)].1a Nevertheless, the molecular structure of 7c
resembles that of the 1-aza-1,3-diene zirconocene com-
plex 2 and exhibits a structural framework that is quite
different from that of the late-transition-metal 1-aza-
1,3-diene complexes. It features a pronounced metal-
lacyclopentene character with a short C1-C2 bond
[1.375(6) Å] and a longer C2-C3 bond [1.446(6) Å],
respectively. This is due to the fact that the 1-aza-1,3-
diene ligand is bonded as a dianion to the metal, thus
giving the internal C1-C2 bond more π character but
the terminal C2-C3 bond more σ character. In late-
transition-metal 1-aza-1,3-diene complexes with η4-π-
bonded 1-aza-1,3-diene ligands, these bonds are of
approximately equal length.12 The linkages between the
titanium and the 1-aza-1,3-diene termini in 7c [Ti-C3
2.278(4) Å, Ti-N 2.016(3) Å] are negligibly longer
compared with other typical titanium to carbon and
titanium to nitrogen σ bonds13 but still close to the sum
of the titanium and nitrogen and the titanium and
carbon covalent radii.14 However, the bond distances
between titanium and the internal 1-aza-1,3-diene
carbon atoms C1/C2 are substantially longer [Ti-C1
2.660(7) Å, Ti-C2 2.715(9) Å]. Therefore, from covalent
radii, it appears that, in contrast to the zirconium
counterpart, no π-interaction exists between the tita-
nium and the unsaturated C1-C2 bond in 7c.
F igu r e 1. Crystal structure of 7c, with anisotropic dis-
placement parameters depicting 50% probability (ORTEP
plot). All the hydrogen atoms of the molecule (except H3)
have been omitted for clarity.
(7b), and 0.66 (7c)] as compared with the corresponding
signal for the late-transition-metal complexes9 and the
signals of the inner 1-aza-1,3-diene hydrogen atoms in
the olefinic region [δ 6.87 and 5.44 (7a ), 6.56 and 5.96
(7b), and 6.70 (7c)] confirm a distinct metallacyclopen-
tene character. Accordingly the 1J CH coupling constants
of the terminal carbon atoms of the 1-aza-1,3-diene
ligands are considerably smaller [1J CH ) 140.2 Hz (7a ),
138.6 Hz (7b), and 133.0 Hz (7c)] than the usual values
for sp2-hybridized carbon atoms (155-160 Hz)10 and
suggest a considerable amount of rehybridization of the
terminal 1-aza-1,3-diene carbon atoms toward sp3 hy-
bridization.
Cr ystal Str u ctu r e of Cp 2Ti[N(c-C6H11)CHdC(Me)-
CH(P h )] (7c). To establish the molecular structures
of 7a -c in more detail, an X-ray crystal structure
analysis of 7c was carried out. The molecular structure
is shown in Figure 1 by an ORTEP drawing with
numbering scheme. Selected bond distances and angles
are listed in Table 1, and crystallographic data are
summarized in the Experimental Section (Table 4 ).
The titanium atom may be described as having a
pseudotetrahedral geometry if the Cp groups are con-
sidered to occupy only two coordination sites and the
1-aza-1,3-diene ligand is assumed to bind via the
terminal carbon C3 and the nitrogen atom N. The
geometrical parameters associated with the Cp2Ti frag-
ment are unexceptional. Thus the Cpc-Ti-Cpc angle
(Cpc ) center of cyclopentadienyl group) of 128.1(2)° and
the average Ti-CCp distance of 2.424(4) Å are typical
of Cp2TiX2 complexes.11 The bent angle between the
(11) (a) Lauher, J . W.; Hoffmann, R. J . Am. Chem. Soc. 1976, 98,
1729. (b) Lappert, M. F.; Pickett, C. J .; Riley, P. I.; Yarrow, P. I. W. J .
Chem. Soc., Dalton Trans. 1981, 805.
(12) tom Dieck, H.; Stamp, L.; Diercks, R.; Mu¨ller, C. Nouv. J . Chim.
1985, 9, 289.
(13) (a) Typical Ti-N bond distances are as follows. Titanium
amides Ti-NR2: 1.939 Å (Allen, F. H.; Kennard, O.; Watson, D. G.;
Brammer, L.; Orpen, A. G.; Taylor, R. J . Chem. Soc., Perkin Trans. 2
1987, S1). [(Me3Si)N{CH2CH2N(SiMe3)}2]TiMe2: 1.905(2), 1.910(2),
1.894(5), 1.905(5) Å (Clark, H. C. S.; Cloke, F. G. N.; Hitchcock, P. B.;
Love, J . B.; Wainwright, A. P. J . Organomet. Chem. 1995, 501, 333).
[(C5H4)SiMe2N(t-Bu)]Ti(NMe2)2: 1.972(4), 1.924(5), 1.906(4) Å (Carpen-
etti, D. W.; Kloppenburg, L.; Kupec, J . T.; Petersen, J . L. Organome-
tallics 1996, 15, 1572). [(Me3Si)NCH2CH2N(SiMe3)]2Ti: 1.903(1),
1.906(1) Å (Herrmann, W. A.; Denk, M.; Albach, R. W.; Behm, J .;
Herdtweck, E. Chem. Ber. 1991, 124, 683). (b) Typical Ti-C bond
distances are as follows. Cp2Ti[o-(CH2)C6H4]: 2.204(4), 2.202(5) Å
(Bristow, G. S.; Lappert, M. F.; Martin, T. R.; Atwood, J . L.; Hunter,
W. F. J . Chem. Soc., Dalton Trans. 1984, 399). Cp2Ti[CH2CH(Ph)CH2]:
2.127(3), 2.113(4) Å (Lee, B. J .; Gajda, G. J .; Schaefer, W. P.; Howard,
T. R.; Ikariya, T.; Straus, D. A.; Grubbs, R. H. J . Am. Chem. Soc. 1981,
103, 7358). Cp2TiMe2: 2.170(2), 2.181(2) Å (Thewalt, U.; Wo¨hrle, Th.
J . Organomet. Chem. 1994, 464, C17). Cp2Ti(CH2Ph)2: 2.239(6), 2.210-
(5) Å (Scholz, J .; Rehbaum, F.; Thiele, K.-H.; Goddard, R.; Betz, P.;
Kru¨ger, C. J . Organomet. Chem. 1993, 443, 93). [PhC(NSiMe3)2]2TiMe2:
2.122(2) Å (Thiele, K.-H.; Windisch, H.; Windisch, H.; Edelmann, F.
T.; Kilimann, U.; Noltemeyer, M. Z. Anorg. Allg. Chem. 1996, 622, 713).
[(c-C6H11)2N]2TiMe2: 2.111(4), 2.118(3) Å (Scoles, L.; Minhas, R.;
Duchateau, R.; J ubb, J .; Gambarotta, S. Organometallics 1994, 13,
4978).
(9) 1H NMR chemical shifts of MAD ligand protons of selected late-
transition-metal MAD complexes are as follows. (a) η4-{(Ph)CH3dCH2-
CH1dN(Ph)}Fe(CO)3 δ (acetone-d6) ) 7.25 (H1), 6.10 (H2), 3.45 (H3):
Otsuka, S.; Yoshida, T.; Nakamura, A. Inorg. Chem. 1967, 6, 20.
Leibfritz, D.; tom Dieck, H. J . Organomet. Chem. 1976, 105, 255.
L’Epplattenier, F.; Calderazzo, F. Inorg. Chem. 1968, 7, 1290. de Chian,
A.; Weiss, R. Acta Crystallogr. 1972, B28, 3264. (b) η4-{(Ph)CH3dCH2-
CH1dN(Ph)}Mo(CO)2(PBu3)2 δ (C6D6) ) 6.15 (H1), 4.55 (H2), 3.20
(H3): Homann, F.; tom Dieck, H.; Franz, K. D.; Ostoja Starzewski, K.
A. J . Organomet. Chem. 1973, 55, 321. (c) η4-{(Ph)CH3dCH2CH1d
N(C6H4-4-Me)}Ru(CO)2(PPh3) δ (CDCl3) ) 6.93 (H1), 5.54 (H2), 2.12
(H3): Beers, O. C. P.; Bouman, M. M.; Elsevier: C. J .; Smeets, W. J .
J .; Spek, A. L. Inorg. Chem. 1993, 32, 3015.
(14) Covalent radii of Ti 1.324 Å, of O 0.73 Å, and of C 0.77 Å: (a)
Pauling, L. Die Natur der chemischen Bindung, 3rd revised ed.; Verlag
Chemie: Weinheim, Germany, 1976. (b) Dean, J . A., Ed. Lange’s
handbook of chemistry, 13th ed.; McGraw-Hill: New York, 1985.
(10) Kalinowski, H. O.; Berger, S.; Braun, S. 13C NMR-Spektroskopie;
G. Thieme: Stuttgart, Germany, 1984.

Titanium 1-Aza-1,3-diene Complexes
Organometallics, Vol. 17, No. 13, 1998 2879
Sch em e 3
One of the most interesting aspects of the molecular
structure of 7c concerns the TiCH group. The hydrogen
atom at C3 was located and refined isotropically, reveal-
ing a close contact between the titanium and H3 at a
distance of 2.38(3) Å. In addition, the acute Ti-C3-
H3 angle [85.5(3)°] lends further support to the exist-
ence of an interaction of H3 with the metal center in
the solid-state structure of 7c. These Ti-C3-H3 struc-
tural parameters compare favorably with the Ti-C-H
angle of 93.5(2)° and the Ti‚‚‚H distance of 2.447(3) Å
found in MeTiCl3(dmpe) or with those of other alkylti-
tanium complexes15 where an R agostic interaction has
been postulated. Agostic C-HFM systems normally
exhibit characteristic features in their NMR spectra.
They may be detected in particular by the value of 1J CH
,
which is lower than that for nonbridged C-H groups.
In addition, the 1H resonances of agostic C-HFM
groups often show high-field shifts.16 However, both the
1J CH coupling constants of the TiCH R carbon atoms of
7a -c, which are within the range of an sp3-hybridized
carbon atom (1J CH ) 133.0-138.6 Hz),10 and the normal
TiCH R proton chemical shift values do not give any
additional information concerning the agostic behavior
of the 1-aza-1,3-diene ligands. Therefore we are re-
served to propose a definitive R-agostic interaction,
although some structural factors might suggest such a
bonding situation.
(Cyclopen tadien yl)titan iu m 1-Aza-1,3-dien e Com -
p lexes. Teuben et al. have found that the reductive
procedure was unsuccessful for the preparation of
electron-deficient titanium 1,3-diene complexes of the
formula Cp*Ti(1,3-diene)Cl. Reduction of Cp*TiCl3 by
Na/Hg did take place, but no complexation of the 1,3-
diene to the metal could be observed.17 Therefore, most
Cp*Ti(1,3-diene)Cl complexes have successfully been
prepared upon treatment of Cp*TiCl3 with 1 equiv of
(2-buten-1,4-diyl)magnesium.18 The utility of the 1,3-
diene magnesium adduct as a synthon of the 1,3-diene
dianion has been widely accepted in the synthesis of 1,3-
diene complexes of early transition metals.19 Surpris-
ingly, no analogous 1-aza-1,3-diene magnesium or di-
lithium adduct as a synthon of the 1-aza-1,3-diene
dianion and starting material for the synthesis of 1-aza-
1,3-diene complexes has been developed up to now.
Fortunately, the simple “one-pot” synthesis described
above for the preparation of 1-aza-1,3-diene metallocene
complexes is also practicable in synthesizing (cyclopen-
tadienyl)titanium 1-aza-1,3-diene complexes of the type
CpTi(MAD)Cl. So the new 1-aza-1,3-diene titanium
complexes 8a -d were prepared in THF by reduction of
CpTiCl3 with magnesium in the presence of the ap-
propriate 1-aza-1,3-dienes 1c-f (Scheme 3).
Purification of the resulting product by recrystalliza-
tion from pentane gives the new 1-aza-1,3-diene com-
plexes as brown (8a ), dark green (8b), or dark red (8c,d )
crystals in 50-71% yield. All of these 14e complexes
are very air sensitive but thermally quite stable for
prolonged periods at 25 °C. They are well soluble in
THF, diethyl ether, and all common hydrocarbon sol-
vents but decompose in chloroform.
1
The H NMR spectra of 8a ,c,d exhibit resonances for
the Cp as well as for the 1-aza-1,3-diene ligand. The
ratio of the integrals of the Cp and 1-aza-1,3-diene
resonances is consistent with the replacement of two
chlorides of CpTiCl3 with one 1-aza-1,3-diene ligand.
1
(15) Agostic interactions in titanium alkyl compounds have been
reported as follows. (a) MeTiCl3(dmpe): Ti-H 2.447(3) Å, Ti-C-H
93.5(2)° (Dawoodi, Z.; Green, M. L. H.; Mtetwa, V. S. B.; Prout, K.;
Schultz, A. J .; Williams, J . M.; Koetzle, T. F. J . Chem. Soc., Dalton
Trans. 1986, 1629). (b) MeTiCl3: Ti-H 2.53 Å, Ti-C-H 101(2)° (Berry,
A.; Dawoodi, Z.; Derome, A. E.; Dickinson, J . M.; Downs, A. J .; Green,
J . C.; Green, M. L. H.; Hare, P. M.; Payne, M. P.; Rankin, D. W. H.;
Robertson, H. E. J . Chem. Soc., Chem. Commun. 1986, 520). (c) Cp*Ti-
(CH2Ph)3: Ti-H 2.32, 2.37 Å (Mena, M.; Pellinghelli, M. A.; Royo, P.;
Serrano, R.; Tiripiccio, A. J . Chem. Soc., Chem. Commun. 1986, 1118).
Furthermore the H NMR spectral data indicate that
the 1-aza-1,3-dienes in 8a ,c,d always adopt the s-cis
geometry since their NMR spectral patterns compare
very closely with those of the 1-aza-1,3-diene zir-
conocene complexes mentioned above.1 The chemical
shift values of the terminal TiCH groups (δ 0.41-0.66)
are reminiscent of the terminal anti protons of the 1,3-
diene ligands for the structurally well-established 1,3-
diene complexes of supine conformation.20,21 Therefore,
it is likely that complexes 8a ,c,d also have the supine
structure.22 Moreover, 8a ,c,d were not found to be
(d) [(µ-η5:η5-C10H8){Ti(CH2Ph)3}2]: Ti-H 2.46, 2.45, 2.48, 2.59
Å
(Alvaro, L. M.; Cuenca, T.; Flores, J . C.; Royo, P.; Pellinghelli, M. A.;
Tiripicchio, A. Organometallics 1992, 11, 3301). (e) CpCp*Ti(CH2-
PPh2)2: Ti-H 2.46(2) Å, Ti-C-H 93(1)° (Cuenca, T.; Flores, J . C.;
Royo, P.; Larsonneur, A.-M.; Choukroun, R.; Dahan, F. Organometallics
1992, 11, 777). (f) [Cp*Ti(CH2SiMe3)2]2(µ-O): Ti-H 2.422, 2.489 Å
(Go´mez-Sal, P.; Mena, M.; Palacios, F.; Royo, P.; Carreras, S. M. J .
Organomet. Chem. 1989, 375, 59). (g) Cp2Ti(µ-CH2)(µ-Me)PtCl-
[PPh(Me)2]: Ti-H 1.93 Å, Ti-C-H 51.7(3)° (Ozawa, F.; Park, J . W.;
Mackenzie, P. B.; Schaefer, W. P.; Henling, L. M.; Grubbs, R. H. J .
Am. Chem. Soc. 1989, 111, 1319).
1
fluxional according to H NMR spectroscopy from -80
to +80 °C.
The 13C NMR chemical shifts for the terminal carbon
atom of the coordinated 1-aza-1,3-dienes in 8a ,c,d (δ
(16) Brookhart, M.; Green, M. L. H. J . Organomet. Chem. 1983, 250,
395. (b) Brookhart, M.; Green, M. L. H.; Wong, L. L. Prog. Inorg. Chem.
1988, 36, 1.
(17) Blenkers, J .; Hessen, B.; van Bolhuis, F.; Wagner, A. J .; Teuben,
J . H. Organometallics 1987, 6, 459.
(19) (a) Fujita, K.; Ohnuma, Y.; Yasuda, H.; Tani, H. J . Organomet.
Chem. 1976, 113, 201. (b) Wreford, S. S.; Whitney, J . F. Inorg. Chem.
1981, 20, 3918 and references therein. (c) Dorf, U.; Engel, K.; Erker,
G. Organometallics 1983, 2, 462.
(18) (a) Yamamoto, H.; Yasuda, H.; Tatsumi, K.; Lee, K.; Nakamura,
A.; Chen, J .; Kai, Y.; Kasai, N. Organometallics 1989, 8, 105. (b) Chen,
J .; Kai, Y.; Kasai, N.; Yamamoto, H.; Yasuda, H.; Nakamura, A. Chem.
Lett. 1987, 1545.
(20) For example: (a) Cp*Ti(2,3-dimethylbuta-1,3-diene)Cl [C6D6:
δ(Hanti) 1.42]; see ref 18. (b) Cp*Zr(2,3-dimethylbuta-1,3-diene)Cl
[THF-d8: δ(Hanti) 0.55], Cp*Hf(2,3-dimethylbuta-1,3-diene)Cl [THF-
d8: δ(Hanti) 0.37]; see ref 17.

2880 Organometallics, Vol. 17, No. 13, 1998
Scholz et al.
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for Cp Ti[N(C6H4-2-Me)CHdC(Me)CH(P h )]Cl
(8c)
Bond Lengths
Molecule A
TiA-ClA 2.3083(6) TiA-N1A 1.923(1) TiA-C1A 2.332(2)
TiA-C2A 2.382(2) TiA-C3A 2.141(1) TiA-H3A 2.47(2)
N1A-C1A 1.383(2) N1A-C4A 1.404(2) C1A-C2A 1.387(2)
C2A-C3A 1.438(2)
Molecule B
TiB-ClB 2.3112(6) TiB-N1B 1.918(1) TiB-C1B 2.332(2)
TiB-C2B 2.380(1) TiB-C3B 2.131(2) TiB-H3B 2.43(2)
N1B-C1B 1.387(2) N1B-C4B 1.425(2) C1B-C2B 1.385(2)
C2B-C3B 1.447(2)
F igu r e 2. Crystal structure of 8c, with anisotropic dis-
placement parameters depicting 50% probability (ORTEP
plot). Only one of the two independent molecules of 8c
(molecule A) is shown. All the hydrogen atoms of the
molecule (except H3) have been omitted for clarity.
Bond Angles
Molecule A
N1A-TiA-ClA
C3A-TiA-ClA
C1A-N1A-TiA
N1A-C1A-C2A
C2A-C3A-TiA
114.34(4)
107.69(4)
88.13(8)
121.1(1)
81.85(8)
N1A-TiA-C3A
C1A-N1A-C4A
C4A-N1A-TiA
C1A-C2A-C3A
TiA-C3-H3A
87.60(5)
123.5(1)
145.5(1)
119.3(1)
97.6(4)
101.43-104.27) differ greatly from the corresponding
values of the 1-aza-1,3-diene titanocene complexes 7a -c
and are significantly shifted to lower field in comparison
with other metal σ-bonded carbon atoms of alkyltita-
sum of angles at N1A: 357.1(1)
(TiA,N1A,C3A)-(N1A,C1A,C2A,C3A)
106.4(4)
Molecule B
1
nium(IV) compounds.23 The J CH coupling constants of
N1B-TiB-ClB
C3B-TiB-ClB
C1B-N1B-TiB
N1B-C1B-C2B
C2B-C3B-TiB
112.10(5)
108.48(4)
88.26(8)
121.0(1)
80.96(8)
N1B-TiB-C3B
C1B-N1B-C4B
C4B-N1B-TiB
C1B-C2B-C3B
TiB-C3-H3B
88.42(5)
121.5(1)
146.0(1)
119.9(1)
97.2(4)
the TiCH methine groups (ca. 137 Hz) are considerably
smaller than the usual value for sp2-hybridized carbon
atoms and suggests a considerable amount of rehybrid-
ization of these methine carbon toward sp3 hybridiza-
tion.10 On the basis of these NMR data, a strong
contribution of a 1-aza-2-titanacyclopent-4-ene structure
to the bonding of the 1-aza-1,3-diene ligand is evident.
Cr ysta l Str u ctu r e of Cp Ti[N(C6H4-2-Me)CHdC-
(Me)CH(P h )]Cl (8c). As a typical example of the CpTi-
(MAD)Cl complexes, CpTi[N(C6H4-2-Me)CHdC(Me)CH-
(Ph)]Cl (8c) was subjected to a crystallographic analysis.
Purple crystals of 8c were grown from pentane by slow
cooling to -20 °C. The X-ray study clearly confirms the
formulation of 8c based on spectroscopic and analytical
data where the 1-aza-1,3-diene ligand lies supine. The
crystal structure shows the presence of two crystallo-
graphically independent molecules per unit cell, which
accidentally look like enantiomeric isomers. The molec-
ular structure of one of the crystallographically inde-
pendent molecules of 8c (molecule A) is shown in Figure
2. Selected bond distances and angles are listed in
Table 2, and crystallographic data are summarized in
the Experimental Section (Table 4).
sum of angles at N1B: 355.7(1)
(TiB,N1B,C3B)-(N1B,C1B,C2B,C3B)
106.2(4)
supine fashion too. From covalent radii, it appears that
interaction of the titanium atom occurs with all four
atoms of the 1-aza-1,3-diene framework. However, the
bond lengths indicate considerably stronger bonding to
the 1-aza-1,3-diene termini C3 and N than to the
internal heterodiene carbon atoms C1 and C2 [Ti-N
1.920(1), Ti-C3 2.136(1), Ti-C2 2.381(1), Ti-C1 2.332-
(2) Å, average of the two molecules]. The difference ∆
) [(Ti-C1 + Ti-C2)/2 - (Ti-N + Ti-C3)/2] ) 0.328 Å
is larger than those in predominantly η4-bonded 1-aza-
1,3-diene complexes [e.g., η4-{(Ph)CHdCHCHdN(C6H4-
4-Me)}Ru(CO)2(PPh3) ∆ ) -0.01 Å9c and η4-{(Ph)CHd
CHCHdN(Ph)}Fe(CO)3 ∆ ) 0.03 Å9a], where all bonded
atoms of the 1-aza-1,3-diene framework are approxi-
mately equidistant from the metal. On the other hand,
∆ of 8c is considerably smaller than ∆ of the corre-
sponding 1-aza-1,3-diene metallocenes 2 (∆ ) 0.424 Å)1
and 7c (∆ ) 0.541 Å). This reflects a larger contribution
of the η4-π bonding of the 1-aza-1,3-diene ligand relative
to the σ2 bonding in 7c.
The structure of 8c closely resembles that of the 1,3-
diene complexes Cp*Ti(2,3-diphenylbuta-1,3-diene)Cl18a
and Cp*Hf(2,3-dimethylbuta-1,3-diene)Cl,17 where the
1,3-diene ligands are bonded to the metal atom in a
Nevertheless, the terminal C2-C3 and N1-C1 bonds
[1.442(2) and 1.385(2) Å] as well as the inner C1-C2
distance [1.386(2) Å, average of the two molecules] show
nearly the same length as in 7c, indicating the presence
of an 1-aza-2-titanacyclopent-4-ene structure.24
(21) For example: (a) Cp*Nb(2,3-dimethylbuta-1,3-diene)Cl2 [C6D6:
δ(Hanti) 0.44], CpTa(buta-1,3-diene)Cl2 [C6D6: δ(Hanti) 0.40] (Okamoto,
T.; Yasuda, H.; Nakamura, A.; Kai, Y.; Kanehisa, N.; Kasai, N. J . Am.
Chem. Soc. 1988, 110, 5008). (b) Yasuda, H.; Tatsumi, K.; Okamoto,
T.; Mashima, K.; Lee, K.; Nakamura, A.; Kai, Y.; Kanehisa, N.; Kasai,
N. J . Am. Chem. Soc. 1985, 107, 2410. (c) Okamoto, T.; Yasuda, H.;
Nakamura, A.; Kai, Y.; Kanehisa, N.; Kasai, N. Organometallics 1988,
7, 2266.
(22) The terms prone and supine used in this text to describe the
mode of 1-aza-1,3-diene orientation in the CpTi(MAD)Cl complexes
were introduced originally by Nakamura and Yasuda to express the
stereochemistry of early-transition-metal diene complexes. They pro-
posed this nomenclature because the classical endo and exo nomen-
clature does not adequately characterize this type of conformation. See
ref 3d.
(24) Remarkably, the 1-aza-1,3-diene ligands in 7c and 8c show a
profound asymmetry in the bond distances of the N-C1-C2-C3 unit.
These intraligand distances compare largely with the corresponding
distances in the 1-aza-1,3-diene zirconocene complex 2 mentioned above
[C2-C3 1.455(3), C1-C2 1.375(3), C1-N 1.385(2) Å].1 It is remarkable
that a similar asymmetry was also found in Cp*Hf(2,3-dimethylbuta-
1,3-diene)Cl, which was attributed to a significant contribution from
an η3,σ-resonance structure.17 We assume that the asymmetry in the
bond distances of the 1-aza-1,3-diene complexes is solely a consequence
of the asymmetric bond length sequence which is already found in
uncomplexed 1-aza-1,3-dienes, e.g. (C6H4-4-Me)NdC1HC2(Me)dC3H-
(Ph) (1f) [C2-C3 1.336(4), C1-C2 1.459(4), C1-N 1.276(3) Å]: Wun-
derle, J .; Scholz, J .; Hovestreydt, E. Z. Kristallogr. 1993, 208, 274.
(23) (a) Berger, S.; Bock, W.; Frenking, G.; J onas, V.; Mu¨ller, F.
J . Am. Chem. Soc. 1995, 117, 3820. (b) Elchenbroich, Ch.; Salzer, A.
Organometallics: a concise introduction; VCH Publishers: Weinheim,
Germany, 1989.

Titanium 1-Aza-1,3-diene Complexes
Organometallics, Vol. 17, No. 13, 1998 2881
Ch a r t 1
Another remarkable feature of 8c is seen in the
Ti‚‚‚H3 distance of 2.45(2) Å [Ti-C3-H3 97.4(4)°],
which is nearly of the same order as that in 7c.
Obviously this is another example where hydrogen
atoms of formally saturated C-H systems closely ap-
proach a metal center,16 by means of which the metallic
atom relieves its electronic deficiency.
F igu r e 3. Molecular structure of complex 9, shown by an
ORTEP plot at the 50% probability level.
NMR Evid en ce of a P r on e Cp Ti(MAD)Cl Com -
p lex. Of particular interest are the unusual NMR
spectra observed for the CpTi(MAD)Cl complex 8b.
Both the 1H and 13C NMR spectra of 8b show two
complete sets of signals which can be attributed to a
complex possessing a supine 1-aza-1,3-diene ligand and
to another exhibiting a prone 1-aza-1,3-diene (relative
ratio 2:3; Chart 1).
compounds with unsaturated carbon-oxygen bonds into
these metal-carbon bonds leads to regioselective carbon-
carbon bond formation. In recent years, especially the
18e Cp2M(1,3-diene) complexes have been investigated.
They can react with carbonyl compounds via two dif-
ferent pathways:4c (a) reaction of the s-trans-η4 isomer
through an η2-coordinated intermediate and C,C-
coupling of the η2-diene with the carbonyl compound and
(b) reaction of the s-cis-σ2,π metallacyclopentene isomer
through direct nucleophilic attack of the diene terminal
carbon atom on the carbonyl functionality.
Noteworthy is that there is only a slight chemical shift
difference in the 13C resonances of the 1-aza-1,3-diene
carbon atoms between the prone and supine isomer but
1
in contrast there is a marked difference in H chemical
Unlike the 1,3-diene analogue, the 1-aza-1,3-diene
zirconocene complexes 2 only react via the second
pathway (b), which proceeds very slowly even at higher
temperature.1 The 1-aza-1,3-diene titanocene complex
7c proved to be inert toward the insertion of acetophe-
none, which might be due to the steric hindrance of the
metal center. Therefore greater reactivity of the 14e
CpTi(MAD)Cl complex 8d was expected. In fact, 8d
readily reacts with 1 equiv of acetophenone at room
temperature in pentane or diethyl ether solution. Chemi-
cal analysis shows that the formed complex contains
both the 1-aza-1,3-diene and one acetophenone per
molecule. Carbon-carbon bond formation between the
heterodiene terminus and the carbonyl carbon atom is
observed. At the same time, a thermodynamically
strong titanium-to-oxygen-linkage is formed (Scheme 3).
According to the NMR spectroscopic data, the novel
seven-membered azoxametallacyclic titanium complex
9 was obtained in good yield (80%).27
The structure and conformation of 9 were confirmed
by a single-crystal X-ray diffraction analysis. A view
of the molecular structure of 9 is shown in Figure 3
together with the numbering scheme used; selected
bond distances and angles are given in Table 3. The
metal center may be considered to possess a typical
three-legged piano-stool environment, with angles in the
range 100.00(8)-102.47(7)° between the legs and with
a distance of 2.024(3) Å to the center of the Cp ring.
Complex 9 exhibits a seven-membered metallacyclic
framework containing four carbon atoms, an oxygen
shift values. Thus, the structurally diagnostic anti
proton (TiCH) and inner proton (NCHd) resonances of
prone-8b occur at δ 4.23 and 5.23, in good agreement
with data for the structurally characterized complex
Cp*Ti(prone-buta-1,3-diene)Cl,18a which is predomi-
nantly π-diene in character. The terminal anti proton
(TiCH: δ 0.37) and the inner proton (NCHd: δ 6.72) of
the 1-aza-1,3-diene ligand of supine-8b exhibit a far
greater dispersion similar to that in complexes such as
Cp*Ti(supine-isoprene)Cl,18a which are predominantly
σ-bound in character. These results indicate that the
η4-π (1-aza-1,3-diene)metal character is more pro-
nounced for the prone isomer (Chart 1, B) as compared
with the supine isomer. In the range -80 to +100 °C,
the isomers supine-8b and prone-8b do not interconvert.
The presence of both the supine and the prone coordina-
tion geometry in 8b indicates that the stability of these
two 1-aza-1,3-diene orientations seems to be well bal-
anced.25 Thus, the relative ratio supine:prone (3:2) must
be determined kinetically during the formation of 8b.26
Rea ction of Cp Ti(MAD)Cl w ith Acetop h en on e.
The 1,3-diene complexes of group 4 metals are known
for their reactive metal-carbon bonds. Insertion of
(25) Nakamura et al. found that, on the basis of extended Hu¨ckel
MO calculations for the model compound CpTi(butadiene)Cl, the prone
and supine isomers were close in energy. The prone isomer is a mere
0.7 kcal/mol more stable than the supine isomer. Therefore, either a
prone or a supine orientation of the diene is electronically accessible
for 14e CpTi(diene)Cl complexes, and the geometrical choice would be
determined by small steric and/or electronic perturbation. See ref 18a.
(26) NMR studies of several CpTi(MAD)Cl complexes revealed that,
similar to those of the corresponding Cp*Ti(diene)Cl complexes,18 the
steric repulsions between the Cp ligand and substituents on the inner
carbon atoms of the 1-aza-1,3-diene ligand may act as the crucial factor
in determining the supine or prone geometry of the coordinated 1-aza-
1,3-diene; i.e., the alkyl substitution on the inner carbon atoms brings
about the supine geometry while nonsubstitution on these carbon
atoms always leads to the prone geometry: Kahlert, S., Scholz, J .
Unpublished results.
(27) Recently Crowe et al. reported the facile participation of a
titanocene Cp ligand in a sequence of carbon-carbon bond forming
reactions that completely removes the Cp ligand from the titanium
center and gives a new titanium complex surprisingly possessing an
η4 1-aza-1,3-diene ligand. This 1-aza-1,3-diene complex cleanly reacts
with acetone forming an insertion product similar to 9: Crowe, W. E.;
Vu, A. T. J . Am. Chem. Soc. 1996, 118, 5508.

2882 Organometallics, Vol. 17, No. 13, 1998
Scholz et al.
of CpTiIV(MAD) complexes will make a variety of
interesting new organic products available in a rather
simple and predictable way. Studies aimed at exploring
such use of the early-transition-metal 1-aza-1,3-diene
complexes which can be treated as equivalents of
metalated allylamines and therefore used as homoeno-
late equivalents are currently being carried out in our
laboratory.29
Ta ble 3. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for Cp Ti[N(C6H4-4-Me)CHdC(Me)-
CH(P h )C(Me)P h O] (9)
Bond Lengths
Ti-O
1.762(2) Ti-N
1.420(3) N-C4
1.578(3) C1-C5
1.935(2) Ti-Cl
2.3046(9)
1.419(3) N-C19 1.435(3)
1.525(4) C1-C6 1.530(4)
O-C1
C1-C2
C2-C3
1.519(3) C2-C12 1.523(3) C3-C4 1.336(3)
C3-C18 1.518(4)
Bond Angles
Exp er im en ta l Section
O-Ti-N 100.00(8) O-Ti-Cl 101.45(6) N-Ti-Cl 102.47(7)
C1-O-Ti 150.1(2) C4-N-Ti 118.0(2) C19-N-Ti 127.4(2)
O-C1-C2 103.8(2) C3-C2-C1 113.4(2) C4-C3-C2 121.5(2)
C3-C4-N 128.2(2)
Gen er a l Con sid er a tion s. All manipulations and reactions
with organometallic compounds were performed in an inert
atmosphere (argon) using Schlenk type glassware. Solvents
were purified and dried by distillation from sodium/benzophe-
none or lithium aluminum hydride under argon prior to use.
Deuterated THF-d8 was treated with sodium/potassium alloy,
then distilled, and stored under argon. The following spec-
trometers were used: NMRsJ EOL J NM-FX 200 (1H, 199.5
MHz; 13C, 50.1 MHz), Varian Gemini 300 (1H, 300.075 MHz;
13C, 75.462 MHz); MSsIntectra AMD 402 (EI MS, 70 eV).
Elemental analyses were carried out at the Mikroanalytisches
Laboratorium des Fachbereichs Chemie der Martin-Luther-
Universita¨t Halle-Wittenberg, Merseburg, Germany. The
starting materials CpTiCl3,30 Cp2TiCl2,31 and the 1-aza-1,3-
dienes 1a -f 32 were prepared according to literature proce-
dures.
atom, a nitrogen atom, and titanium. Very typically,
the azoxatitanacycloheptene ring adopts a folded ring
conformation in the solid state similar to that previously
observed for the zirconocene complex 6, which appears
(on the basis of the internal angles) to contain very little
strain at each of the constituent atoms.1 To a first
approximation the atoms of the s-cis-configured 1-aza-
1,3-diene unit are arranged coplanar (maximum devia-
tion -0.022 Å); the atoms Ti, N, O, and C1 are also
arranged almost in one plane. The angle between these
two planes is 127.2(2)°. Much of the rigidity of the cyclic
seven-membered framework in 9 is due to the large
angle at the ring oxygen atom [Ti-O-C1 150.1(2)°].
This indicates some oxygen to titanium electron π-dona-
tion which may serve to decrease the electron deficiency
at the Lewis acidic titanium center.28
The carbonyl addition product contains three chiral
centers as parts of the ring perimeter {[CpTi*(NR-)-
(O-)Cl], TiC*H(Ph)-, and OC*(Ph)Me-} and thus gives
rise to the occurrence of diastereomers. However, the
NMR analysis of 9 (for details see Experimental Section)
has revealed that only a single isomer is obtained,
indicating that this coupling reaction has taken place
with high stereoselectivity. Thus, the simple ring
expansion of 8d with acetophenone to produce 9 fits into
the general scheme established for the reaction course
taken upon addition of carbonyl compounds to early-
transition-metal alkyl complexes.
X-r a y Diffr a ction of 7c, 8c, a n d 9. Suitable crystals were
grown from saturated pentane (7c, 8c) or diethyl ether
solutions (9) at -20 °C. Data were collected on an Enraf-
Nonius CAD4 diffractometer using Mo KR radiation (λ )
0.7107 Å). The unit cell parameters were obtained by a least-
squares fit of 25 reflections. Three standard reflections were
monitored every 2 h. No systematic variations in intensities
were found. Data were corrected for Lorentz and polarization
effects but not for absorption.33 The structures were solved
by direct methods34 and refined by full-matrix least-squares
2
35
procedures against Fo
.
The hydrogen atoms were located
from the difference maps and refined isotropically for com-
pounds 7c and 9. For compound 8c, only the hydrogen atoms
H1A, H1B, H3A, and H3B were located from the difference
map and refined isotropically; all other hydrogen atoms were
included at calculated positions with fixed thermal parameters.
All non-hydrogen atoms were refined anisotropically. Cell
constant and other pertinent data were collected, and are
recorded in Table 4.
Cp 2Ti[N(t-Bu )CHdCHCH(P h )] (7a ). A solution of Cp2-
TiCl2 (5.00 g, 20.08 mmol) and 1a (3.76 g, 20.10 mmol) in 100
mL of THF was stirred with magnesium turnings (0.49 g, 20.16
mmol) for 48 h at room temperature. Subsequently the THF
was pumped off and the resultant dark violet solid extracted
with 50 mL of diethyl ether. Concentrating and cooling the
extract to -20 °C yielded large black violet crystals of 7a (3.82
Con clu d in g Rem a r k s
In this paper we have reported the synthesis of a
variety of (cyclopentadienyl)titanium complexes bearing
1-aza-1,3-diene ligands. The results of this study show
that the CpTiIVCl- and the Cp2TiIV- complex fragments
are effective building blocks for the stabilization of a
novel series of 1-aza-1,3-diene titanium complexes. The
crystal structures of 7c and 8c are the first examples
of crystallographically characterized 1-aza-1,3-diene
titanium complexes.
The CpTi(MAD)Cl complexes 8a -d are more reactive
than the previously synthesized 1-aza-1,3-diene zir-
conocene complexes 2, which might be due to the steric
hindrance of the metal center. From the example
presented and discussed in this study, it can be expected
that carbon-carbon coupling reactions of carbonyl
compounds with the 1-aza-1,3-diene dianion equivalent
g, 10.45 mmol, 52%; mp 103-107 °C). Anal. Calcd for C23H27
-
NTi (Mr ) 365.35): C, 75.61; H, 7.45; N, 3.83. Found: C,
(29) (a) Ahlbrecht, H. Chimia 1977, 31, 391. (b) Werstiuk, N. H.
Tetrahedron 1983, 39, 205. (c) Ahlbrecht, H.; Farnung, W. Chem. Ber.
1984, 117, 1. (d) Ahlbrecht, H.; Enders, D.; Santowski, L.; Zimmer-
mann, G. Chem. Ber. 1989, 122, 1995.
(30) (a) King, R. B. Organomet. Synth. 1965, 1, 78. (b) Gorsich, R.
D. J . Am. Chem. Soc. 1960, 82, 4211.
(31) Birmingham, J . M. Adv. Organomet. Chem. 1964, 2, 365.
(32) (a) Doebner, O.; Miller, W. Ber. Dtsch. Chem. Ges. 1883, 16,
1664. (b) A revised procedure to prepare N-alkylated 1-aza-1,3-dienes
will be published in: Kahlert, S. Ph.D. Thesis, Universita¨t Halle, 1998.
(33) MOLEN: An Interactive Structure Solution Procedure; Enraf-
Nonius: Delft, The Netherlands, 1990.
(34) Sheldrick, G. M. SHELXS-86: A Computer Program for Crystal
Structure Solution; University of Go¨ttingen: Go¨ttingen, Germany,
1986.
(35) Sheldrick, G. M. SHELXL-93: A Computer Program for Crystal
Structure Refinement; University of Go¨ttingen: Go¨ttingen, Germany,
1993.
(28) (a) Gau, H.-M.; Lee, C.-S.; Lin, C.-C.; J iang, M.-K.; Ho, Y.-C.;
Kuo, C.-N. J . Am. Chem. Soc. 1996, 118, 2936. (b) Beckhaus, R.;
Strauss, I.; Wagner, T. J . Organomet. Chem. 1994, 464, 155. (c) Wu,
Y.-T.; Ho, Y.-C.; Lin, C.-C.; Gau, H.-M. Inorg. Chem. 1996, 35, 5948
and literature cited therein.

Titanium 1-Aza-1,3-diene Complexes
Organometallics, Vol. 17, No. 13, 1998 2883
Ta ble 4. Cr ysta llogr a p h ic Da ta a n d Deta ils of Da ta Collection a n d Refin em en t for 7c, 8c, a n d 9
7c
8c
9
empirical formula
Mr
C
26H31NTi
C22H22NClTi
383.76
C30H30NOClTi
503.90
405.42
cryst syst
space group
temp, K
monoclinic
P21/c (No. 14)
183(2)
orthorhombic
P212121 (No. 19)
293(2)
monoclinic
P21/n (No. 14)
293(2)
a, Å
b, Å
c, Å
7.620(2)
14.701(3)
19.106(4)
94.59(3)
2133.4(8)
0.40 × 0.38 × 0.36
4
1.262
0.412
2-55
5002
13.804(4)
14.347(6)
19.849(2)
8.619(3)
12.784(3)
23.811(4)
92.49(1)
2621(1)
0.42 × 0.38 × 0.20
4
1.277
0.451
2-55
6084
â, deg
V, Å3
3931(2)
cryst dimens, mm3
no. of formula units Z
Dc, g‚cm-3
0.30 × 0.30 × 0.36
8
1.297
0.575
2-55
5360
4887
468
0.045
0.120
0.66
abs coeff µ, mm-1
2θ range, deg
no. of reflns collected
no. of obsd data with I > 2σ(I)
no. of variables
R1
4851
377
0.057
0.152
5942
416
0.043
0.103
wR2
rest electron density, e‚Å-3
0.48
0.30
75.43; H, 7.60; N, 3.99. 1H NMR (300 MHz, THF-d8, 20 °C):
δ 7.15 (t, 2H; m-Ph), 7.00 (d, 2H; o-Ph), 6.87 (d, 3J HH ) 5.4 Hz,
1H; NCHdCH), 6.80 (t, 1H; o-Ph), 5.68 (s, 5H; Cp), 5.44 (dd,
CMe), 1.91-1.07 (m, 10H; c-C6H11), 0.66 (br s, 1H; TiCH). 13C
NMR (75 MHz, THF-d8, 25 °C): δ 147.98 (s; i-Ph), 132.37 (d,
1
1J CH ) 160.8 Hz; NCHdCMe), 128.23 (d, J CH ) 155.9 Hz;
3
1
1
3J HH ) 5.5 Hz, J HH ) 9.7 Hz, 1H; NCHdCH), 5.00 (s, 5H;
o/m-Ph), 127.39 (d, J CH ) 155.3 Hz; o/m-Ph), 122.76 (d, J CH
1
Cp), 1.28 (s, 9H; CMe3), 1.18 (d, 3J HH ) 9.7 Hz, 1H; TiCH). 13
C
) 157.5 Hz; p-Ph), 120.76 (s; NCHdCMe), 108.31 (d, J CH )
1 1
NMR (75 MHz, THF-d8, 25 °C): δ 148.04 (s; i-Ph), 130.11 (d,
171.4 Hz; Cp), 103.17 (d, J CH ) 171.1 Hz; Cp), 84.22 (d, J CH
) 133.0 Hz; TiCH), 66.54, 37.62, 36.10, 27.46, 27.40, 26.90
1J CH ) 161.3 Hz; NCHdCH), 128.66 (d, 1J CH ) 158.1 Hz; o/m-
1
1
1
Ph), 124.54 (d, J CH ) 154.8 Hz; o/m-Ph), 122.90 (d, J CH
)
(C6H11), 21.32 (q, J CH ) 126.0 Hz; NCHdCMe). EIMS, m/z
1
161.3 Hz; p-Ph), 108.48 (d, J CH ) 171.1 Hz; Cp), 102.22 (d,
(relative intensity, assignment): 405 (15, M+), 226 (38, M+
Cp2Ti), 178 (100, Cp2Ti+).
-
1J CH ) 172.8 Hz; Cp), 100.41 (d, J CH ) 146.7 Hz; NCHdCH),
1
1
80.31 (d, J CH ) 140.2 Hz; TiCH), 60.14 (s; CMe3), 32.89 (q,
Cp Ti[N(c-C6H11)CHdC(Me)CH(P h )]Cl (8a ). To a solu-
tion of CpTiCl3 (5.00 g, 22.80 mmol) and the 1-aza-1,3-diene
1c (5.18 g, 22.80 mmol) in THF (150 mL) were added
magnesium turnings (0.55 g, 22.80 mmol) over a period of 12
h at -20 °C. The reaction mixture was stirred at ambient
temperature until the magnesium was dissolved. Then, the
mixture was evaporated to dryness, and the product was
extracted with diethyl ether (100 mL) to leave magnesium
chloride. The dark brown extract was concentrated to 50 mL
and stored at -20 °C for 3 days. A yield of 4.37 g (11.62 mmol,
51%) of large brown crystals of 8a was obtained (mp 119-122
°C). Anal. Calcd for C21H26NClTi (Mr ) 375.78): C, 67.12;
H, 6.97; N, 3.73. Found: C, 66.72; H, 6.75; N, 3.81. 1H NMR
(300 MHz, CD2Cl2, 20 °C): δ 7.25 (t, 2H; m-Ph), 7.09 (t, 1H;
p-Ph), 6.83 (s, 1H; NCHdCMe), 6.82 (d, 2H; o-Ph), 6.17 (s, 5H;
Cp), 3.69 (m, 1H; C6H11), 2.06 (s, 3H; NCHdCMe), 1.95-1.17
(m, 10H; C6H11), 0.41 (s, 1H; TiCH). 13C NMR (75 MHz, CD2-
1J CH ) 125.5 Hz; CMe3).
Cp 2Ti[N(C6H4-4-Me)CHdCHCH(P h )] (7b). The reaction
was performed by the same method described for the prepara-
tion of 7a , using Cp2TiCl2 (5.00 g, 20.08 mmol), 1b (4.45 g,
20.08 mmol), and magnesium turnings (0.49 g, 20.16 mmol).
A yield of 5.29 g (13.25 mmol, 66%) of black-green crystals
was obtained (mp ca. 110 °C dec). Anal. Calcd for C26H25NTi
(Mr ) 399.37): C, 78.19; H, 6.31; N, 3.51. Found: C, 78.10;
H, 6.23; N, 3.67. 1H NMR (300 MHz, THF-d8, 20 °C): δ 7.18
(t, 2H; m-Ph), 7.05 (d, 4H; o-Ph, o/m-C6H4-4-Me), 6.83 (t, 1H;
3
p-Ph), 6.64 (d, 2H; o/m-C6H4-4-Me), 6.56 (d, J HH ) 5.4 Hz,
3
3
1H; NCHdCH), 5.96 (dd, J HH ) 5.5 Hz, J HH ) 8.3 Hz, 1H;
NCHdCH), 5.74 (s, 5H; Cp), 5.18 (s, 5H; Cp), 2.31 (s, 3H; C6H4-
3
4-Me), 1.67 (d, J HH ) 8.1 Hz, 1H; TiCH). 13C NMR (75 MHz,
THF-d8, 25 °C): δ 152.58 (s; i-C6H4-4-Me), 149.05 (s; i-Ph),
1
133.01 (s; p-C6H4-4-Me), 131.95 (d, J CH ) 170.4 Hz; NCHd
1
1
CH), 128.60 (d, J CH ) 155.5 Hz; o/m-C6H4-4-Me, o/m-Ph),
Cl2, 25 °C): δ 142.19 (s; i-C6H5), 128.16 (d, J CH ) 158.6 Hz;
1
1
1
128.88 (d, J CH ) 157.1 Hz; o,m-C6H4-4-Me, o/m-Ph), 124.74
o/m-Ph), 127.87 (d, J CH ) 158.5 Hz; o/ m-Ph), 124.78 (d, J CH
1
1
1
(d, J CH ) 155.5 Hz; o/m-C6H4-4-Me, o/m-Ph), 123.65 (d, J CH
) 160.6 Hz; p-Ph), 118.58 (d, J CH ) 173.0 Hz; NCHdCMe),
1
) 157.6 Hz; o/m-C6H4-4-Me, o/m-Ph), 122.91 (d, J CH ) 158.4
115.17 (s; NCHdCMe), 112.41 (d, 1J CH ) 173.9 Hz; Cp), 101.43
1
1
1
Hz; p-Ph), 109.71 (d, J CH ) 155.0 Hz; NCHdCH), 109.05 (d,
(d, J CH ) 137.4 Hz; TiCH), 68.11 (d, J CH ) 135.4 Hz; C6H11),
1 1
1J CH ) 173.0 Hz; Cp), 104.08 (d, J CH ) 173.0 Hz; Cp), 79.76
36.16 (t, J CH ) 129.7 Hz; C6H11), 34.34 (t, J CH ) 128.5 Hz;
C6H11), 26.06 (t; C6H11), 26.05 (t; C6H11), 25.77 (t; C6H11), 18.27
1
1
1
(d, J CH ) 138.6 Hz; TiCH), 20.69 (q, J CH ) 126.0 Hz; C6H4-
4-Me). EIMS, m/z (relative intensity, assignment): 399 (10,
M+), 220 (100, M+ - Cp2Ti), 178 (36, Cp2Ti+), 128 (8, C9H6N+),
91 (10, C7H7+).
1
(q, J CH ) 128.0 Hz; NCHdCMe). EIMS, m/z (relative inten-
sity, assignment): 375 (100, M+), 340 (5, M+ - Cl), 309 (4, M+
- Cp), 292 (12, M+ - C6H11), 265 (19, M+ - C7H12N), 263 (19,
M+ - C7H14N), 244 (19, M+ - C10H10), 226 (16, M+ - CpTiCl),
148 (30, CpTiCl+).
Cp 2Ti[N(c-C6H11)CHdC(Me)CH(P h )] (7c). The reaction
was performed by the same method described for the prepara-
tion of 7a , using Cp2TiCl2 (5.00 g, 20.08 mmol), 1c (4.57 g,
20.08 mmol), and magnesium turnings (0.49 g, 20.16 mmol).
A yield of 5.31 g (13.10 mmol, 65%) of black-green crystals
was obtained (mp 121-124 °C). Subsequent recrystallization
from diethyl ether at -5 °C gave crystals suitable for an X-ray
analysis. Anal. Calcd for C26H31NTi (Mr ) 405.42): C, 77.03;
H, 7.71; N, 3.45. Found: C, 76.80; H, 7.60; N, 3.84. 1H NMR
(300 MHz, THF-d8, 20 °C): δ 7.13 (t, 2H; m-Ph), 6.98 (d, 2H;
o-Ph), 6.81 (t, 1H; p-Ph), 6.70 (s, 1H; NCHdCMe), 5.55 (s, 5H;
Cp), 5.04 (s, 5H; Cp), 3.39 (m, 1H; c-C6H11), 2.30 (s, 3H; NCHd
Cp Ti[N(t-Bu )CHdC(Me)CH(P h )]Cl (8b). The reaction
was performed by the same method described for the prepara-
tion of 8a , using CpTiCl3 (5.00 g, 22.80 mmol), 1d (4.59 g, 22.80
mmol), and magnesium turnings (0.55 g, 22.80 mmol). A yield
of 4.62 g (13.22 mmol, 58%) of a dark green crystalline solid
composed of a 3:2 mixture (1H NMR) of the prone and supine
isomers was obtained. Anal. Calcd for C19H24NClTi (Mr
)
349.74): C, 65.25; H, 6.92; N, 4.00. Found: C, 65.46; H, 7.09;
N, 4.14. 1H NMR (300 MHz, THF-d8, 20 °C): su pin e-8b δ
3
7.18 (m, 3H; m/p-Ph), 6.87 (s, 1H; NCHdCMe), 6.79 (d, J HH

2884 Organometallics, Vol. 17, No. 13, 1998
Scholz et al.
) 7.3 Hz, 2H; o-Ph), 6.21 (s, 5H; Cp), 2.00 (s, 3H; NCHdCMe),
1.34 (s, 9H; CMe3), 0.41 (s, 1H; TiCH); pr on e-8b δ 7.18 (m,
5H; Ph), 5.84 (s, 5H; Cp), 5.77 (s, 1H; NCHdCMe), 3.93 (s,
1H; TiCH), 1.97 (s, 3H; NCHdCMe), 1.31 (s, 9H; CMe3). 1H
NMR (C6D6): su pin e-8b δ 7.14 (m, 3H; m/p-Ph), 6.83 (d, 3J HH
) 7.3 Hz, 2H; o-Ph), 6.72 (s, 1H; NCHdCMe), 6.09 (s, 5H; Cp),
2.10 (s, 3H; NCHdCMe), 1.05 (s, 9H; CMe3), 0.37 (s, 1H; TiCH);
pr on e-8b δ 7.18 (m, 5H; Ph), 5.56 (s, 5H; Cp), 5.23 (s, 1H;
NCHdCMe), 4.23 (s, 1H; TiCH), 1.52 (s, 3H; NCHdCMe), 1.16
(s, 9H; CMe3). 13C NMR (75 MHz, THF-d8, 25 °C): su pin e-
8b δ 143.15 (s; i-Ph), 128.94 (d, 1J CH ) 157.8 Hz; o/m-Ph), 128.0
(d, 1J CH ) 158.0 Hz; o/m-Ph), 125.66 (d, 1J CH ) 161.0 Hz; p-Ph),
g, 22.80 mmol), and magnesium turnings (0.55 g, 22.80 mmol).
A yield of 6.21 g (16.19 mmol, 71%) of dark red crystals was
obtained (mp 98-100 °C). Anal. Calcd for C22H22NClTi
(383.76): C, 68.86; H, 5.78; N, 3.65. Found: C, 68.34; H, 5.92;
N, 3.51. 1H NMR (300 MHz, THF-d8, 20 °C): δ 7.26-7.04 (m,
6H; m/p-C6H4-4-Me, m/p-Ph), 6.73 (s, 1H; NCHdCMe), 6.30
(s, 5H; Cp), 2.32 (s, 3H; NCHdCMe), 2.14 (s, 3H; C6H4-4-Me),
0.54 (s, 1H; TiCH). 13C NMR (75 MHz, THF-d8, 25 °C): δ
150.12 (s; i-C6H4-4-Me), 142.46 (s; i-Ph), 134.80 (s; p-C6H4-4-
1
1
Me), 130.09 (d, J CH ) 157.2 Hz; o/m-Ph), 128.91 (d, J CH
)
1
157.5 Hz; o/ m-Ph), 128.48 (d, J CH ) 158.5 Hz; o/ m-C6H4-4-
Me), 125.63 (d, 1J CH ) 160.7 Hz; p-Ph), 122.34 (d, 1J CH ) 159.0
1
1
119.79 (d, J CH ) 173.6 Hz; NCHdCMe), 116.01 (s; NCHd
Hz; o/ m-C6H4-4-Me), 119.51 (s; NCHdCMe), 119.32 (d, J CH
CMe), 113.23 (d, 1J CH ) 174.1 Hz; Cp), 103.75 (d, 1J CH ) 141.4
) 177.0 Hz; NCHdCMe), 114.00 (d, J CH ) 174.4 Hz; Cp),
1
1
1
1
Hz; TiCH), 62.98 (s; CMe3), 31.77 (q, J CH ) 126.4 Hz; CMe3),
104.27 (d, J CH ) 136.6 Hz; TiCH), 18.22 (q, J CH ) 128.2 Hz;
20.21 (q, 1J CH ) 128.2 Hz; NCHdCMe); pr on e-8b δ 142.97 (s;
NCHdCMe), 17.88 (q, J CH ) 127.1 Hz; C6H4-4-Me). EIMS,
1
1
1
i-Ph), 126.78 (d, J CH ) 157.0 Hz; o/m-Ph), 126.64 (d, J CH
)
m/z (relative intensity, assignment): 384 (100, M+), 234 (95,
M+ - CpTiCl), 148 (25, CpTiCl+), 105 (20, C8H7N+).
1
158.0 Hz; o/m-Ph), 125.41 (d, J CH ) 161.4 Hz; p-Ph), 112.22
1
1
(d, J CH ) 174.3 Hz; Cp), 108.11 (d, J CH ) 171.3 Hz; NCHd
Cp Ti[N(C6H4-2-Me)CHdC(Me)CH(P h )C(Me)P h O] (9).
To a diethyl ether solution (50 mL) of 8d (1.15 g, 3.0 mmol)
was added acetophenone (362 µL, 3.1 mmol) at room temper-
ature via syringe. The mixture was stirred at ambient
temperature for 12 h and then concentrated. Cooling of the
solution to -20 °C gave 9 as red crystals. The carbonyl
addition product was purified by recrystallization from diethyl
ether at -5 °C. A yield of 1.20 g (2.4 mmol, 80%) of bright
1
CMe), 104.72 (s; NCHdCMe), 100.91 (d, J CH ) 132.4 Hz;
TiCH), 59.51 (s; CMe3), 30.88 (q, 1J CH ) 126.2 Hz; CMe3), 18.66
1
(q, J CH ) 128.2 Hz; NCHdCMe). EIMS, m/z (relative inten-
sity, assignment): 349 (100, M+), 314 (14, M+ - Cl), 292 (25,
M+ - C4H9), 265 (38, M+ - C5H12N), 263 (38, M+ - C5H14N),
226 (14, M+ - CpTiCl), 148 (36, CpTiCl+).
Cp Ti[N(C6H4-2-Me)CHdC(Me)CH(P h )]Cl (8c). The re-
action was performed by the same method described for the
preparation of 8a , using CpTiCl3 (5.00 g, 22.80 mmol), 1e (5.37
g, 22.80 mmol), and magnesium turnings (0.55 g, 22.80 mmol).
A yield of 5.69 g (14.82 mmol, 65%) of dark red crystals was
obtained (mp 135-137 °C). Subsequent recrystallization from
n-pentane or diethyl ether at -5 °C gave crystals suitable for
red crystals was obtained (mp 120 °C). Anal. Calcd for C30H30
-
NOClTi (Mr ) 503.89): C, 71.50; H, 6.00; N, 2.78. Found: C,
70.94; H, 5.87; N, 2.69. 1H NMR (300 MHz, THF-d8, 20 °C):
3
δ 7.56-7.02 (m, 10H; 2Ph), 7.16 (d, J HH ) 8.1 Hz, 2H; C6H4-
3
4-Me), 6.87 (d, J HH ) 8.1 Hz, 2H; C6H4-4-Me), 6.42 (s, 5H;
Cp), 6.16 (s, 1H; NCHdCMe), 3.53 (s, 1H; CHPh), 2.34 (s, 3H;
C6H4-4-Me), 1.59 (s, 3H; NCHdCMe), 1.33 (s, 3H; OC(Me)Ph).
13C NMR (75 MHz, THF-d8, 25 °C): δ 144.79 (i-C6H4-4-Me),
139.79 (i-Ph), 139.04 (i-Ph), 135.67 (p-C6H4-4-Me), 131.83,
131.61, 130.23, 130.05, 128.82, 128.44, 128.15, 127.97, 127.60,
124.58 (CHdC(Me), C6H4-4-Me, Ph), 117.08 (Cp), 104.93
(OC(Me)Ph), 65.67 (CHPh), 28.44 (OC(Me)Ph), 21.93 (NCHd
CMe), 20.97 (C6H4-4-Me).
an X-ray analysis. Anal. Calcd for
C22H22NClTi (Mr )
383.76): C, 68.86; H, 5.78; N, 3.65. Found: C, 68.59; H, 5.92;
N, 3.51. 1H NMR (300 MHz, THF-d8, 20 °C): δ 7.26-7.04 (m,
1
6H; m/p-C6H4-2-Me, m/p-Ph), 6.90 (d, J HH ) 7.4 Hz, 3H;
o-C6H4-2-Me, o-Ph), 6.73 (s, 1H; NCHdCMe), 6.12 (s, 5H; Cp),
2.09 (s, 3H; C6H4-2-Me), 2.06 (s, 3H; NCHdCMe), 0.66 (s, 1H;
TiCH). 13C NMR (75 MHz, THF-d8, 25 °C): δ 152.16 (s; i-C6H4-
2-Me), 142.60 (s; i-Ph), 131.83 (s; o-C6H4-2-Me), 131.04 (d, 1J CH
1
) 155.3 Hz; C6H4-2-Me), 128.92 (d, J CH ) 163.1 Hz; o/m-Ph),
Ack n ow led gm en t. Prof. Dr. K.-H. Thiele and Prof.
Dr. D. Steinborn are kindly acknowledged for their
interest and for providing laboratory facilities. This
work was financially supported by the Deutsche Fors-
chungsgemeinschaft and Bayer AG.
1
1
128.46 (d, J CH ) 158.0 Hz; o/m-Ph), 127.08 (d, J CH ) 161.7
Hz; C6H4-2-Me), 126.61 (d, 1J CH ) 160.5 Hz; C6H4-2-Me), 126.40
1
1
(d, J CH ) 155.9 Hz; C6H4-2-Me), 125.57 (d, J CH ) 160.8 Hz;
1
C6H4-2-Me), 122.36 (d, J CH ) 177.6 Hz; NCHdCMe), 116.26
1
(s; NCHdCMe), 113.72 (d, J CH ) 174.3 Hz; Cp), 103.40 (d,
1J CH ) 137.2 Hz; TiCH), 18.22 (q, J CH ) 128.2 Hz; NCHd
1
Su p p or tin g In for m a tion Ava ila ble: For compounds 7c,
8c, and 9, tables of crystal data and structure refinement
details, atomic coordinates, displacement parameters, and all
bond distances and angles (21 pages). Ordering information
is given on any current masthead page.
1
CMe), 17.88 (q, J CH ) 127.1 Hz; C6H4-2-Me). EIMS, m/z
(relative intensity, assignment): 383 (10, M+), 234 (27, M+
CpTiCl), 148 (48, CpTiCl+), 77 (100, C6H5+).
-
Cp Ti[N(C6H4-4-Me)CHdC(Me)CH(P h )]Cl (8d ). The re-
action was performed by the same method described for the
preparation of 8a , using CpTiCl3 (5.00 g, 22.80 mmol), 1f (5.37
OM970640J