Reactivity of Group 4 Metal Alkyl and Metallacyclic Compounds Supported by Aryloxide Ligands Toward Organic Isocyanides

Article abstract of DOI:10.1021/om990413c

The reactivity of the dimethyl compound [Ti(OC₆H₃Ph₂-2,6)₂Me₂] (1) and titanabicyclic compounds [(ArO)₂Ti(CH₂CH(C₄H₈)CHCH ₂)] (6,7) (formed by trans-coupling of 1,7-octadiene) toward organic isocyanides has been investigated. Dimethyl 1 reacts with 1 equiv of 2,6dimethylphenylisocyanide (xyNC) to produce a cyclometalated product [Ti(OC₆H₃Ph₂2,6)(OC₆H ₃Ph-η₁C₆H₄){N(xy)CHMe ₂}] (2) which was structurally characterized. Compound 2 is believed to arise via CH bond activation within an intermediate η²-imine (azatitanacyclopropane) formed by transfer of both methyl groups to the isocyanide. With an excess of xyNC, 1 produces an intermediate bis(η²-iminoacyl) 4, which slowly converts to the enediamide [Ti(OC₆H₃Ph₂-2,6)2{N(xy)CMeCMeN(xy)}] (5). The solid-state structure of 5 shows the presence of a folded diazatitanacyclopent-3-ene ring formed by intramolecular coupling of the two iminoacyl groups. Titanabicyclic compounds 6 and 7 react with Bu^tNC and xyNC respectively to generate products 8 and 9, which both contain amide ligands derived by CH bond activation and an iminoacyl group formed by insertion into the new Ti-C bond. The solid-state structure of [Ti(OC₆H₃Ph₂-2,6){OC₆H ₃Ph-(η²-(C₆H₄)CNBu ^t)}{Bu^tNCH(C₈H₁₄)}] (8) shows a trans-fusion between the five- and six-membered carbon rings as found in the initial titanabicycle 6. The treatment of 1 with xyNC in the presence of excess 3-hexyne or styrene produces azatitanacyclopent-2-ene 10 and azatitanacyclopentane 11 derivatives, respectively. These arise via coupling of the alkyne or olefin with an intermediate η²-imine. The solid-state structure of [Ti(OC₆H₃Ph₂-2,6)₂{N(xy)C(Me ₂)C(Et)C(Et)}] (10) confirms its formulation.

Full text of DOI:10.1021/om990413c

4442
Organometallics 1999, 18, 4442-4447
Rea ctivity of Gr ou p 4 Meta l Alk yl a n d Meta lla cyclic
Com p ou n d s Su p p or ted by Ar yloxid e Liga n d s Tow a r d
Or ga n ic Isocya n id es
Matthew G. Thorn, Phillip E. Fanwick, and Ian P. Rothwell*
Department of Chemistry, 1393 Brown Building, Purdue University,
West Lafayette, Indiana 47907-1393
Received J une 1, 1999
The reactivity of the dimethyl compound [Ti(OC6H3Ph2-2,6)2Me2] (1) and titanabicyclic
compounds [(ArO)2Ti(CH2CH(C4H8)CHCH2)] (6, 7) (formed by trans-coupling of 1,7-octadiene)
toward organic isocyanides has been investigated. Dimethyl 1 reacts with 1 equiv of 2,6-
dimethylphenylisocyanide (xyNC) to produce a cyclometalated product [Ti(OC6H3Ph2-
2,6)(OC6H3Ph-η1-C6H4){N(xy)CHMe2}] (2), which was structurally characterized. Compound
2 is believed to arise via CH bond activation within an intermediate η2-imine (azatitana-
cyclopropane) formed by transfer of both methyl groups to the isocyanide. With an excess of
xyNC, 1 produces an intermediate bis(η2-iminoacyl) 4, which slowly converts to the
enediamide [Ti(OC6H3Ph2-2,6)2{N(xy)CMeCMeN(xy)}] (5). The solid-state structure of 5
shows the presence of a folded diazatitanacyclopent-3-ene ring formed by intramolecular
coupling of the two iminoacyl groups. Titanabicyclic compounds 6 and 7 react with ButNC
and xyNC respectively to generate products 8 and 9, which both contain amide ligands
derived by CH bond activation and an iminoacyl group formed by insertion into the new
Ti-C bond. The solid-state structure of [Ti(OC6H3Ph2-2,6){OC6H3Ph-(η2-(C6H4)CNBut)}{But-
NCH(C8H14)}] (8) shows a trans-fusion between the five- and six-membered carbon rings as
found in the initial titanabicycle 6. The treatment of 1 with xyNC in the presence of excess
3-hexyne or styrene produces azatitanacyclopent-2-ene 10 and azatitanacyclopentane 11
derivatives, respectively. These arise via coupling of the alkyne or olefin with an intermediate
η2-imine. The solid-state structure of [Ti(OC6H3Ph2-2,6)2{N(xy)C(Me2)C(Et)C(Et)}] (10)
confirms its formulation.
In tr od u ction
η2-type binding modes are possible. However, for high-
valent, electron-deficient, early d-block, lanthanide, and
The migratory insertion of organic isocyanides (RNC)
into early transition metal-alkyl, -hydride, -silyl,
-amido, and -phosphido bonds is an important reaction
in organometallic chemistry that has received consider-
able study over the last 25 years.1,2 The insertion
chemistry of RNC with cationic group 4 transition metal
systems has also recently received attention.3 Much of
this interest has stemmed from the importance of
relating this chemistry to the isoelectronic carbon
monoxide (CO) molecule. The use of CO as a chemical
feedstock through its activation by transition metal
complexes and its subsequent conversion into useful
organic molecules through migratory insertion-reduc-
tive elimination type reactions is an important area of
study. Since organometallic compounds derived from
reactions with RNC are generally more stable than their
CO counterparts, in terms of the reversibility of inser-
tion, their isolation and characterization is much easier.
Therefore, RNC reactivity is often used as a model for
CO reactivity.
(2) (a) Riley, P. N.; Fanwick, P. E.; Rothwell, I. P. Chem. Commun.
1997, 1109. (b) Giannini, L.; Caselli, A.; Solari, E.; Floriani, C.; Chiesa-
Villa, A.; Rizzoli, C.; Re, N.; Sgamelloti, A. J . Am. Chem. Soc. 1997,
119, 9198. (c) Barriola, A. M.; Cano, A. M.; Cuenca, T.; Fernandez, F.
J .; Gomez-Sal, P.; Manzanero, A.; Royo, P. J . Organomet. Chem. 1997,
542, 247. (d) Fandos, R.; Lanfranchi, M.; Otero, A.; Pellinghelli, M. A.;
Ruiz, M. J .; Terreros, P. Organometallics 1996, 15, 4725. (e) Kloppen-
burg, L.; Petersen, J . L. Organometallics 1997, 16, 3548. (f) Kloppen-
burg, L.; Petersen, J . L. Polyhedron 1995, 14, 69. (g) Giannini, L.;
Solari, E.; Angelis, S. D.; Ward, T. R.; Floriani, C.; Chiesa-Villa, A.;
Rizzoli, C. J . Am. Chem. Soc. 1995, 117, 5801. (h) J acoby, D.; Isoz, S.;
Floriani, C.; Chiesa-Villa, A.; Rizzoli, C. J . Am. Chem. Soc. 1995, 117,
2805. (i) Angelis, S. D.; Solari, E.; Floriani, C.; Chiesa-Villa, A.; Rizzoli,
C. Organometallics 1995, 14, 4505. (j) Campora, J .; Buchwald, S. L.;
Gutierrez-Puebla, E.; Monge, A. Organometallics 1995, 14, 2039. (k)
Bendix, M.; Grehl, M.; Frohlich, R.; Erker, G. Organometallics 1994,
13, 3366. (l) Zambrano, C. H.; Fanwick, P. E.; Rothwell, I. P.
Organometallics 1994, 13, 1174. (m) Lemke, F. R.; Szalda, D. J .;
Bullock, R. M. Organometallics 1992, 11, 876. (n) Lubben, T. V.; Plossi,
K.; Norton, J . R.; Miller, M. M.; Anderson, O. P. Organometallics 1992,
11, 122. (o) Beshouri, S. M.; Chebi, D. E.; Fanwick, P. E.; Rothwell, I.
P.; Huffman, J . C. Organometallics 1990, 9, 2375. (p) Berg, F. J .;
Petersen, J . L. Organometallics 1989, 8, 2461. (q) Erker, G.; Zwettler,
R.; Kruger, C. Chem. Ber. 1989, 122, 1377. (r) Erker, G.; Korek, U.;
Petersen, J . L. J . Organomet. Chem. 1988, 355, 121.
(3) (a) Ahlers, W.; Temme, B.; Erker, G.; Frohlich, R.; Fox, T. J .
Organomet. Chem. 1997, 527, 191. (b) Temme, B.; Erker, G.; Frohlich,
R.; Grehl, M. Angew. Chem., Int. Ed. Engl. 1994, 33, 1480. (c) Guram,
A. S.; Guo, Z.; J ordan, R. F. J . Am. Chem. Soc. 1993, 115, 4902. (d)
Bochmann, M.; Wilson, L. M.; Hursthouse, M. B.; Motevalli, M.
Organometallics 1988, 7, 1148. (e) Bochmann, M.; Wilson, L. M.;
Hursthouse, M. B.; Short, R. L. Organometallics 1987, 6, 2556. (f)
Bochmann, M.; Wilson, L. M. J . Chem. Soc., Chem. Commun. 1986,
1610.
An important characteristic feature of acyl, iminoacyl,
and related transition metal complexes is the way in
which the ligand binds to the metal center. Both η1- and
(1) Durfee, L. D.; Rothwell, I. P. Chem. Rev. 1988, 88, 1059, and
references therein.
10.1021/om990413c CCC: $18.00 © 1999 American Chemical Society
Publication on Web 09/17/1999

Reactivity of Group 4 Metal Alkyl Compounds
Organometallics, Vol. 18, No. 21, 1999 4443
Sch em e 1
actinide metals the η2-binding mode [LnM(η2-YCN)] (Y
) CR3, H, SiR3, NR2, PR2) is preferred.1
1 equiv) led to the yellow orthometalated titanium
amido complex 2 (Scheme 1). Presumably the formation
of 2 arises via a pathway involving initial insertion of
xyNC into one Ti-Me bond to form the corresponding
mono(η2-iminoacyl) complex. A second methyl migration
then occurs, forming an η2-imine complex (see below for
further reactivity studies which confirm the presence
of this intermediate). Finally, C-H bond activation of
one of the ortho-phenyl rings of an aryloxide ligand
Resu lts a n d Discu ssion
Previous work in the Rothwell group has demon-
strated that the dialkyl substrates of stoichiometry [Ti-
(OC6H3Pri -2,6)2(R)2] (OC6H3Pri -2,6 ) 2,6-diisopropy-
2
2
lphenoxide; R ) Me, CH2Ph, CH2SiMe3) will react with
organic isocyanides (2 equiv) to form bis(η2-iminoacyl)
1
occurs leading to 2 (Scheme 1).6 The H NMR spectrum
compounds. The resulting compounds [Ti(OC6H3Pri -
of 2 shows a septet at δ 3.01, assigned to the NCHMe2
2
2,6)2(η2-RNCR)2] have been shown to subsequently
methine proton that was transferred from the acti-
undergo intramolecular coupling of the η2-iminoacyl
1
vated CH bond. Also present in the H and 13C NMR
groups to produce enediamide ligands, [Ti(OC6H3Pri -
spectra are signals for diastereotopic NCHMe2 methyl
groups and nonequivalent xy-ortho-Me groups. The
nonequivalence of the xylyl-methyl groups reflects
restricted rotation on the NMR time scale of this aryl
group.
The solid-state structure of 2 was also obtained
(Figure 1, Table 1). The molecular structure of 2 is best
described as pseudo-tetrahedral about the titanium
metal center. The six-membered metallacycle ring has
a Ti-O-C angle of 130.2(1)° compared to 163.5(1)° for
the terminal aryloxide Ti-O-Ar angle.
2
2,6)2(RNC{R}dC{R}NR)].4 It has also been shown that
the dibenzyl compound [Ti(OC6H3Pri -2,6)2(CH2Ph)2]
2
will react with ButNC (1 equiv) to form the stable,
structurally characterized mono(η2-iminoacyl) com-
pound [Ti(OC6H3Pri -2,6)2(η2-ButNCCH2Ph)(CH2PH)],
2
which will react with pyridine ligands (L, 1 equiv) to
produce η2-imine compounds [Ti(OC6H3Pri -2,6)2(η2-But-
2
NC{CH2Ph}2)(L)] in high yields.5
The reactivity of the dimethyl titanium complex [Ti-
(OC6H3Ph2-2,6)2Me2] (1) with organic isocyanides dem-
onstrates both similar and contrasting chemistry to that
above. The major difference in reactivity appears to be
due to the ease of cyclometalation of this ligand.
Treatment of 1 with 2,6-dimethylphenylisocyanide (xyNC,
Treatment of 2 with 4-phenylpyridine led to the light-
green, five-coordinate titanium amido complex 3 (Scheme
1), characterized by microanalysis and NMR spectros-
1
copy. The most distinguishing feature in the H NMR
spectrum of 3 is the NCHMe2 methine septet at δ 5.46,
which is dramatically downfield shifted compared with
the signal for this proton in precursor 2.
(4) (a) Chamberlain, L. R.; Durfee, L. D.; Fanwick, P. E.; Kobriger,
L. M.; Latesky, S. L.; McMullen, A. K.; Steffey, B. D.; Rothwell, I. P.;
Folting, K.; Huffman, J . C. J . Am. Chem. Soc. 1987, 109, 6068. (b)
Durfee, L. D.; Kobriger, L. M.; McMullen, A. K.; Rothwell, I. P. J . Am.
Chem. Soc. 1988, 110, 1463.
(5) Durfee, L. D.; Hill, J . E.; Fanwick, P. E.; Rothwell, I. P.
Organometallics 1990, 9, 75.
(6) For C-H bond activation of aryloxide ligands at group 4 metal
centers see: Latesky, S. L.; McMullen, A. K.; Rothwell, I. P.; Huffman,
J . C. J . Am. Chem. Soc. 1985, 107, 5981.

4444 Organometallics, Vol. 18, No. 21, 1999
Thorn et al.
F igu r e 1. ORTEP (50% thermal elipsoids) view of [Ti-
(OC6H3Ph2-2,6)(OC6H3Ph-η1-C6H4){N(xy)CHMe2}] (2).
F igu r e 2. ORTEP (50% thermal elipsoids) view of [Ti-
(OC6H3Ph2-2,6)2{N(xy)CMeCMeN(xy)}] (5).
Ta ble 1. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for
[Ti(OC6H3P h 2-2,6)(OC6H3P h -η1-C6H4){N(xy)CHMe2}],
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for [Ti(OC6H3P h 2-2,6)2{N(xy)CMeCMeN(xy)}],
2
Ti-O(1)
Ti -O(2)
Ti -N(4)
1.829(1)
1.804(1)
1.894(2)
Ti -C(122)
N(4)-C(41)
N(4)-C(47)
2.075(2)
1.446(2)
1.487(2)
5
molecule 1
Ti(1)-O(13)
Ti(1)-O(16)
Ti(1)-N(11)
Ti(1)-N(14)
Ti(1)-C(12)
O(13)-Ti(1)-O(16)
1.811(2) Ti(1)-C(13)
2.394(3)
1.396(4)
1.379(4)
1.391(5)
97.1(1)
O(1)-Ti-O(2)
O(1)-Ti-N(4)
O(1)-Ti-C(122)
O(2)-Ti-N(4)
O(2)-Ti-C(122)
N(4)-Ti-C(122)
118.36(6)
116.55(6)
88.38(7)
117.46(7)
106.67(7)
102.41(7)
Ti-O(1)-C(11)
Ti-O(2)-C(21)
Ti-N(4)-C(41)
Ti-N(4)-C(47)
C(41)-N(4)-C(47)
130.2(1)
163.5(1)
113.9(1)
131.7(1)
114.3(2)
1.864(2) N(11)-C(12)
1.927(3) N(14)-C(13)
1.919(3) C(12)-C(13)
2.391(3) O(16)-Ti(1)-C(13)
115.7(1) N(11)-Ti(1)-N(14)
87.7(1)
91.6(2)
O(13)-Ti(1)-N(11) 111.0(1) Ti(1)-N(14)-C(13)
O(13)-Ti(1)-N(14) 110.6(1) N(14)-C(13)-C(12) 117.2(3)
O(13)-Ti(1)-C(12) 143.5(1) C(13)-C(12)-N(11) 117.4(3)
Treatment of excess xyNC with 1 led to the bis(η2-
iminoacyl) complex 4 (Scheme 1), which could not be
isolated but was spectroscopically characterized. Hence
it appears that the second insertion can compete with
the second methyl migration within the intermediate
mono(iminoacyl). The formation of 4 was most easily
observed by noting the 13C NMR resonance of the
iminoacyl carbon (δ241.1). A solution of bis(η2-iminoacyl)
4 was also observed (1H NMR, C6D6) to convert cleanly
to a new product (5) over the course of several days.
Layering of the final benzene solution with hexane
afforded dark red crystals of the titanium enediamide
5. The enediamide complex arises through intramolecu-
lar coupling of the η2-iminoacyl groups of 4. Coupling
of η2-iminoacyl ligands at group 4 metal centers has
been extensively studied.4
O(13)-Ti(1)-C(13) 142.8(1) N(11)-C(12)-Ti(1)
O(16)-Ti(1)-N(11) 114.6(1) N(14)-C(13)-Ti(1)
53.7(2)
53.3(1)
O(16)-Ti(1)-N(14) 113.9(1) Ti(1)-O(13)-C(131) 174.6(2)
O(16)-Ti(1)-C(12) 97.2(1)
molecule 2
1.863(2) Ti(2)-C(23)
Ti(1)-O(16)-C(161) 161.2(2)
Ti(2)-O(23)
Ti(2)-O(26)
Ti(2)-N(21)
Ti(2)-N(24)
Ti(2)-C(22)
2.392(3)
1.398(4)
1.395(4)
1.381(5)
142.9(1)
87.8(1)
1.811(2) N(21)-C(22)
1.930(3) N(24)-C(23)
1.925(3) C(22)-C(23)
2.390(3) O(26)-Ti(2)-C(23)
O(23)-Ti(2)-O(26) 115.9(1) N(21)-Ti(2)-N(24)
O(23)-Ti(2)-N(21) 114.9(1) Ti(2)-N(24)-C(23)
90.8(2)
O(23)-Ti(2)-N(24) 114.0(1) N(24)-C(23)-C(22) 117.2(3)
O(23)-Ti(2)-C(22) 97.3(1)
O(23)-Ti(2)-C(23) 96.9(1)
C(23)-C(22)-N(21) 117.8(3)
N(21)-C(22)-Ti(2)
53.9(2)
53.6(1)
O(26)-Ti(2)-N(21) 110.9(1) N(24)-C(23)-Ti(2)
O(26)-Ti(2)-N(24) 110.2(1) Ti(2)-O(23)-C(231) 161.1(2)
O(26)-Ti(2)-C(22) 143.4(1) Ti(2)-O(26)-C(261) 175.3(2)
Solid-state structural analysis of 5 (Figure 2, Table
2) shows a puckering of the five-membered diazamet-
allacycle ring, resulting in the olefinic carbon atoms
being brought closer to the metal center, possibly as an
effort to relieve its electron deficiency. This type of
structural distortion has been previously observed for
cyclometalated species 3 except that a further equiva-
lent of isocyanide has inserted into the cyclometalated
Ti-C(aryl) bond. In this case it therefore appears that
formation of the imine by ring closure within the
monoiminoacyl intermediate is faster than the second
insertion (Scheme 2). It has previously been shown that
treatment of metallacyclopentadiene rings with isocya-
nide leads to η2-imine derivatives, which do not undergo
cyclometalation.
1
related enediamide complexes.4 In the H NMR spec-
trum of 5, nonequivalent xylylmethyl signals show that
both flipping of the nonplanar structure and aryl
rotation are slow on the NMR time scale.
The reactivity described above for 1 contrasts with
that found for the trans-titanabicyclic compounds
[(ArO)2Ti(CH2CH(C4H8)CHCH2)] 6 and 7 formed by
intramolecular coupling of 1,7-octadiene (Scheme 2).
Treatment of 6 and 7 with excess isocyanide led to
orange products 8 and 9 (Scheme 2) that contain 2 equiv
of isocyanide. Compounds 8 and 9 are related to the
Analysis of the solid-state structure of 8 (Figure 3,
Table 3) shows the molecule to be pseudo-tetrahedral
if one assumes that the η2-iminoacyl ligand occupies a
single coordination site. Also indicated from the solid-
state structure of 8 is that the bicyclic substituent of
the amide ligand possess the trans-stereochemistry that
is also present in the precursor 6. There is evidence in
7

Reactivity of Group 4 Metal Alkyl Compounds
Organometallics, Vol. 18, No. 21, 1999 4445
Sch em e 2
Ta ble 3. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for [Ti(OC6H3P h 2-2,6){OC6H3P h -(η2-
(C6H4)CNBu t)}{Bu tNCH(C8H14)}], 8
Ti-O(1)
Ti-O(3)
Ti-N(1)
Ti-N(2)
1.858(2)
1.902(2)
2.085(2)
1.907(3)
Ti-C(120)
N(1)-C(120)
N(2)-C(22)
2.000(3)
1.258(4)
1.478(4)
O(1)-Ti-O(3)
O(1)-Ti-N(1)
O(1)-Ti-N(2)
O(1)-Ti-C(120)
O(3)-Ti-N(1)
O(3)-Ti-N(2)
O(3)-Ti-C(120)
104.2(1)
N(1)-Ti-N(2)
110.3(1)
35.8(1)
105.6(1)
75.8(2)
68.4(2)
142.6(2)
166.0(2)
119.7(1)
103.9(1)
88.2(1)
100.18(9)
119.4(1)
127.8(1)
N(1)-Ti-C(120)
N(2)-Ti-C(120)
Ti-C(120)-N(1)
C(120)-N(1)-Ti
Ti-O(1)-C(11)
Ti-O(3)-C(31)
useful for the construction of cyclic and noncyclic
compounds containing nitrogen heteroatoms. The for-
mation of an η2-imine complex upon the treatment of 1
with 1 equiv of RNC was not observed but rather
inferred on the basis of the formation of the final ortho-
metalated product 2 (Scheme 1). However, trapping of
the η2-imine complex with alkynes or olefins was
achieved by prior addition of a large excess of 3-hexyne
or styrene to 1 to RNC addition (Scheme 3). The
resulting azatitanacyclopent-4-ene 10 and azatitanacy-
clopentane 11 species are formed from the reductive
coupling of the η2-imine (formed from RNC) and 3-hex-
yne or styrene, respectively. If a large amount of
F igu r e 3. ORTEP (50% thermal elipsoids) view of [Ti-
(OC6H3Ph2-2,6){OC6H3Ph-(η2-(C6H4)CNBut)}{ButNCH-
(C8H14)}] (8).
the solution 1H and 13C NMR spectra of 8 for two
isomeric species being present in solution. For example,
the 13C NMR of 8 shows two iminoacyl resonances (δ
225.1 and 224.7), along with four Ti-O-C ipso carbon
(δ 161.3, 160.9, 160.6, 160.6) and four N-CMe3 (δ 29.7,
29.6, 28.91, 28.88) resonances, respectively. We inter-
pret these data as being evidence for the presence of
two diastereoisomers in the reaction product. These
isomers are related by the stereochemistries of the three
chiral carbon atoms within the amido substituent.
There has also been some investigation into the
coupling of isocyanides with alkynes and olefins at group
4 metal centers.7,8 These coupling reactions are often
(7) Thorn, M. G.; Hill, J . E.; Waratuke, S. A.; J ohnson, E. J .;
Fanwick, P. E.; Rothwell, I. P. J . Am. Chem. Soc. 1997, 119, 8630,
and references therein.
(8) For recent and leading references see: (a) Probert, G. D.; Whitby,
R. J .; Coote, S. J . Tetrahedron Lett. 1995, 36, 4113. (b) Campora, J .;
Buchwald, S. L.; Gutierrez-Puebla, E.; Monge, A. Organometallics
1995, 14, 2039.

4446 Organometallics, Vol. 18, No. 21, 1999
Thorn et al.
Sch em e 3
Ta ble 4. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for
[Ti(OC6H3P h 2-2,6)2{N(xy)C(Me2)C(Et)C(Et)}], 10
Ti-O(2)
1.841(1)
1.829(1)
1.881(1)
2.053(2)
1.506(2)
1.540(2)
C(3)-C(4)
N(10)-C(11)
C(7)-C(8)
C(7)-C(9)
C(3)-C(2)
C(4)-C(5)
1.345(2)
1.443(2)
1.535(3)
1.535(3)
1.521(2)
1.514(2)
Ti -O(3)
Ti-N(10)
Ti-C(4)
N(10)-C(7)
C(7)-C(3)
O(2)-Ti-O(3)
O(2)-Ti-C(4)
O(2)-Ti-N(10)
O(3)-Ti-C(4)
O(3)-Ti-N(10)
N(10)-Ti-C(4)
119.98(6)
102.15(6)
121.81(6)
109.91(6)
110.70(6)
84.73(7)
Ti-N(10)-C(7)
N(10)-C(7)-C(3)
C(7)-C(3)-C(4)
Ti-C(4)-C3)
Ti-O(2)-C(21)
Ti-O(3)-C(31)
117.6(1)
106.3(1)
120.2(2)
110.6(2)
166.5(1)
150.8(1)
Exp er im en ta l Section
All operations were carried out under
a
dry nitrogen
atmosphere using standard Schlenk techniques. The hydro-
carbon solvents were distilled from sodium benzophenone and
stored over sodium ribbons under nitrogen until use. All other
reagents were purchased from Aldrich Chemical Co., Inc., or
F igu r e 4. ORTEP (50% thermal elipsoids) view of [Ti-
(OC6H3Ph2-2,6)2{N(xy)C(Me2)C(Et)C(Et)}] (10).
3-hexyne or styrene was not used, then a substantial
amount of orthometalated product 2 was observed (1H
NMR) to form. Even in the presence of excess alkyne
or olefin, small amounts of 2 were generated, which
hampered purification. However, both 10 and 11 were
characterized spectroscopically, and the regiochemistry
of these organometallic products was readily confirmed
by NMR methods.9 Specifically in the case of 11 the Ti-
CHPh resonance at δ101.6 ppm compares with a value
of 107.5 ppm found for the Ti-CHPh signal in azati-
tanacyclopentane [Ti(OC6H3Ph2-2,6)2{CH(Ph)CH2CH-
(Ph)N(Ph)}].7
The solid-state structure of azatitanacyclopent-4-ene
10 was also obtained (Figure 4, Table 4). The molecular
structure of 10 is best described as pseudo-tetrahedral,
with bond distances and angles similar to other com-
pounds of this type. The C(3)-C(4) bond distance is
noticeably shorter [1.345(2) Å] than the C-C single bond
distances in 10, as expected.
1
Strem and used without further purification. The H and 13C
NMR spectra were recorded on a Varian Associates Gemini-
200, Inova-300, or General Electric QE-300 spectrometer and
referenced to protio impurities of commercial benzene-d6 or
deuterated chloroform as internal standards. Mass spectra,
elemental analyses, and molecular structures were obtained
through Purdue in-house facilities.
Syn th esis of [Ti(OC6H3P h 2-2,6)(OC6H3P h -η1-C6H4){N(xy)-
CHMe2}] (2). A sample of [Ti(OC6H3Ph2-2,6)2Me2] (1) (500 mg,
0.88 mmol) was dissolved in benzene. One equivalent of xyNC
(115 mg, 0.88 mmol) dissolved in benzene was added, and the
mixture was stirred for 30 min and evacuated to dryness. A
minimal amount of hexane was added and upon standing
yellow crystals of 2 formed (490 mg, 80%). Anal. Calcd for
C
47H41NO2Ti: C, 80.68; H, 5.91; N, 2.00. Found: C, 80.49; H,
6.11; N, 1.89. 1H NMR (C6D6, 30 °C): δ 6.56-7.60 (aromatics);
3.01 [sp, 3J (1H-1H) ) 6.3 Hz, CH]; 1.40 (s), 1.34 (s, xyMe);
1.18 (d), 0.50 [d, 3J (1H-1H) ) 6.3 Hz, CHMe2]. 13C NMR (C6D6,
30 °C): δ 159.5 (Ti-O-C); 142.4, 140.4, 140.2, 138.5, 135.4,
135.2, 133.7, 133.4, 130.8, 130.6, 129.7, 129.3, 129.2, 128.5,
127.3, 126.8, 126.7, 126.5, 126.4, 124.6, 121.9 (aromatic); 61.6
(NCH); 23.6, 23.5, 20.5, 18.3 (Me).
(9) (a) Buchwald, S. L.; Watson, B. T.; Wannamaker, M. W.; Dewan,
J . C. J . Am. Chem. Soc. 1989, 111, 4486. (b) Buchwald, S. L.;
Wannamaker, M. W.; Watson, B. T. J . Am. Chem. Soc. 1989, 111, 776.
Syn th esis of [Ti(OC6H3P h 2-2,6)(OC6H3P h -η1-C6H4){N(xy)-
CHMe2}] (2). A sample of 2 was dissolved in benzene-d6 in a

Reactivity of Group 4 Metal Alkyl Compounds
Organometallics, Vol. 18, No. 21, 1999 4447
NMR tube and titrated with 4-phenylpyridine, causing a
change in the color of the solution from yellow to yellow/green.
The solution was layered with hexane, inducing the formation
of yellow/green crystals of 3. Anal. Calcd for C58H50N2O2Ti: C,
xyMe); 1.71 [q, 3J (1H-1H) ) 7.6 Hz, CH2CH3]; 0.98 (m,
CH2CH3); 0.72 (s, NCMe2). 13C NMR (C6D6, 30 °C): δ 217.7
(Ti-C); 159.7 (Ti-O-C); 140.2, 136.0, 133.2, 130.6, 129.6,
128.6, 128.5, 128.4, 126.8, 125.6, 121.4 (aromatic); 67.6 (NC-
Me2); 27,4 (xyMe); 20.7, (NCMe2); 21.2, 20.7 (CH2CH3); 15.0,
14.5 (CH2CH3).
1
81.49; H, 5.89; N, 3.28. Found: C, 80.36; H, 5.92; N, 2.88. H
3
NMR (C6D6, 30 °C): δ 8.54 [d, J (1H-1H) ) 7.0 Hz, ortho-py);
6.56-7.60 (aromatics); 5.46 [sp, 3J (1H-1H) ) 5.9 Hz, CH]; 1.76
(s), 1.23 (s, xyMe); 0.77 (d), 0.74 (d, CHMe2]. 13C NMR (C6D6,
30 °C): δ 159.8, 158.1 (Ti-O-C); 150.4, 142.0, 137.0, 135.2,
134.1, 131.0, 130.8, 129.7, 129.6, 129.3, 128.8, 128.3, 127.8
(aromatic); 60.4 (NCH); 23.6, 22.0, 20.1, 19.7 (Me).
Syn t h e sis
of
[Ti(OC6H 3P h 2-2,6)2{N(xy)C(Me 2)-
CH2CHP h }] (11). A sample of [Ti(OC6H3Ph2-2,6)2Me2] (1) (300
mg, 0.53 mmol) was dissolved in benzene along with a large
excess of styrene (approximately 2 mL). One equivalent of
xyNC (70 mg, 0.53 mmol) dissolved in benzene was slowly
added, and the mixture was stirred overnight and evacuated
to dryness, affording a red oil. 1H NMR (C6D6, 30 °C): δ 6.56-
7.16 (aromatics); 4.08 (m, CHPh); 3.54 (dd), 2.56 (dd, CH2);
2.10 (s), 1.07 (s, xyMe); 0.77 (s), 0.55 (s, CMe2). 13C NMR (C6D6,
30 °C): δ 159.6 (Ti-O-C); 148.3, 135.6, 135.0, 131.1, 130.2,
129.8, 129.3, 129.1, 128.9, 128.8, 128.7, 128.4, 128.3, 127.3,
127.1, 126.9, 125.4, 125.2, 124.2, 121.8 (aromatic); 101.6 (Ti-
CHPh), 63.6 (xyNC); 39.8, 31.9, 25.7, 28.2, 21.9, 20.4. A
minimal amount of hexane was added, and upon extended
standing dark red crystals formed, which were determined to
be the enediamide compound 9. Presumably formation of 9
occurred due to the presence of excess isocyanide being present
in the initial reaction mixture, which lead to the formation
of 8.
Syn th esis of [Ti(OC6H3P h 2-2,6)2(η2-xyNCMe)2] (4). To an
excess of xyNC dissolved in deuterated benzene was added [Ti-
(OC6H3Ph2-2,6)2Me2] (1), initially forming a red solution of the
bis(η2-iminoacyl) product 4, which could be spectroscopically
characterized. 1H NMR (C6D6, 30 °C): δ 6.70-7.59 (aromatics);
1.54 (s, xyMe); 1.10 (s, NCMe). 13C NMR (C6D6, 30 °C): δ 241.1
(NCMe); 161.3 (Ti-O-C); 144.9, 141.2, 132.1, 130.8, 130.2,
130.1, 128.8, 128.3, 128.2 (aromatic); 21.0 (NCMe); 18.2 (xyMe).
Syn th esis of [Ti(OC6H3P h 2-2,6)2{N(xy)CMeCMeN(xy)}]
(5). Over the course of several days compound 4 slowly
converted to 5 as monitored by NMR. Layering of the resulting
benzene solution with hexane afforded dark red crystals of 5.
Anal. Calcd for C56H50N2O2Ti: C, 80.95; H, 6.07; N, 3.37.
1
Found: C, 80.88; H, 6.00; N, 3.44. H NMR (C6D6, 30 °C): δ
6.71-7.28 (aromatic); 1.70 (s), 1.38 (s, xyMe); 1.44 (s, CMe).
13C NMR (C6D6, 30 °C): δ 158.8 (Ti-O-C); 146.6, 141.0, 139.6,
134.1, 133.2, 132.9, 131.0, 130.3, 130.1, 129.9, 129.8, 129.7,
129.3, 129.3, 128.7, 128.5, 127.5, 127.1, 127.0, 126.6, 126.0,
123.9, 121.6, 120.4, 110.7 (aromatic); 31.9 (CMe); 19.2, 15.3
(xyMe).
X-r a y Da ta Collection a n d Red u ction . Full details are
contained in the Supporting Information. A suitable crystal
was mounted on a glass fiber in a random orientation under
a cold stream of dry nitrogen. Preliminary examination and
final data collection were performed with Mo KR radiation (λ
) 0.71073 Å) on a Nonius Kappa CCD. Lorentz and polariza-
tion corrections were applied to the data.10 An empirical
absorption correction using SCALEPACK was applied.11 In-
tensities of equivalent reflections were averaged. The structure
was solved using the structure solution program PATTY in
DIRDIF92.12 The remaining atoms were located in succeeding
difference Fourier syntheses. Hydrogen atoms were included
in the refinement but restrained to ride on the atom to which
they are bonded. The structure was refined in full-matrix least-
Syn t h esis of [Ti(OC6H3P h 2-2,6){OC6H3P h -(η2-(C6H4)-
CNBu t)}{Bu tNCH(C8H14)}] (8). A sample of [Ti(OC6H3Ph2-
2,6)2{CH2CH(C4H8)CHCH2}] (6) (200 mg, 0.31 mmol) was
dissolved in benzene. Six equivalents of tert-butylisocyanide
(209 µL, 1.85 mmol) was added, and the mixture was stirred
for 1 h and then evacuated to dryness, affording a crude solid,
which was recrystalized as orange crystals of 8 from benzene/
pentane (150 mg, 60%). Anal. Calcd for C54H58N2O2Ti: C,
1
2
2
79.59; H, 7.17; N, 3.44. Found: C, 79.73; H, 7.05; N, 3.18. H
squares, where the function minimized was ∑w(|Fo| - |Fc| )2,
NMR (C6D6, 30 °C): δ 6.67-7.66 (aromatics); 0.26-2.90
(aliphatics); 0.84 (s), 0.83 (s), 0.76 (s), 0.75 [s, NC(CH3)3]. 13C
NMR (C6D6, 30 °C): δ 225.1, 224.7 (η2-NC); 161.3 160.9, 160.6,
160.6 (Ti-O-C); 143.8, 143.6, 142.3, 141.7, 141.5, 141.4, 134.5,
134.3, 133.9, 133.6, 133.4, 133.1, 132.0, 131.8, 131.0, 130.3,
130.2, 130.1, 128.9, 128.5, 127.8, 126.8, 126.6, 126.1, 122.5,
122.4, 120.9, 119.3 (aromatic); 62.0, 61.8, 61.4, 60.5, 59.1, 58.9,
(NC); 46.7, 46.6, 46.4, 46.3, 46.1, 44.6, 43.8, 43.7, 32.9, 32.5,
31.9, 31.6, 27.1, 26.9 (aliphatics); 29.7, 29.6, 28.91, 28.88 [NC-
(CH3)3].
and the weight w is defined as w ) 1/[σ2(Fo2) + (0.0585P)2 +
2
1.4064P], where P ) (Fo + 2Fc2)/3.
Scattering factors were taken from the “International Tables
for Crystallography”.13 Refinement was performed on a Al-
phaServer 2100 using SHELX-97.14 Crystallographic drawings
were done using the programs ORTEP.15
Ack n ow led gm en t. We thank the National Science
Foundation (Grant CHE-9700269) for financial support
of this research.
Syn th esis of [Ti(OC6HP h 4-2,3,5,6){OC6HP h 3-(η2-(C6H4)-
CNxy)}{Bu tNCH(C8H14)}] (9). A sample of [Ti(OC6HPh4-
2,3,5,6)2(CH2CH(C4H8)CHCH2)] (7) (200 mg, 0.20 mmol) was
dissolved in benzene. Two equivalents of xyNC was added, and
the mixture was stirred for 1 h and then evacuated to dryness,
affording a crude solid, which was recrystallized as orange
crystals from benzene/pentane (90 mg, 37%). Anal. Calcd for
C86H74N2O2Ti: C, 84.99; H, 6.14; N, 2.30. Found: C, 85.59; H,
6.48; N, 2.10.
Su p p or tin g In for m a tion Ava ila ble: Description of the
experimental procedures for X-ray diffraction studies. Tables
of thermal parameters, bond distances and angles, intensity
data, torsion angles, and mutiplicities for 2, 5, 8, and 10. This
material is available free of charge via the Internet at
http://pubs.acs.org.
OM990413C
Syn th esis of [Ti(OC6H3P h 2-2,6)2{N(xy)C(Me2)C(Et)C-
(Et)}] (10). A sample of [Ti(OC6H3Ph2-2,6)2Me2] (1) (500 mg,
0.88 mmol) was dissolved in benzene along with a large excess
of 3-hexyne (approximately 2 mL). One equivalent of xyNC
(115 mg, 0.88 mmol) dissolved in benzene was slowly added,
and the mixture was stirred overnight and then evacuated to
dryness. A minimal amount of hexane was added, and upon
standing both yellow (minor) and orange crystals formed. The
minor contaminant was observed to be 4. The major component
was the title complex. 1H NMR (C6D6, 30 °C): δ 6.58-7.42
(aromatics); 1.84 [q, 3J (1H-1H) ) 7.6 Hz, CH2CH3]; 1.77 (s,
(10) McArdle, P. C. J . Appl. Crystallogr. 1996, 239, 306.
(11) Otwinowski, Z.; Minor, W. Methods Enzymol. 1996, 276.
(12) Beurskens, P. T.; Admirall, G.; Beurskens, G.; Bosman, W. P.;
Garcia-Granda, S.; Gould, R. O.; Smits, J . M. M.; Smykalla, C. The
DIRDIF92 Program System, Technical Report; Crystallography Labo-
ratory, University of Nijmegen: The Netherlands, 1992.
(13) International Tables for Crystallography, Vol. C; Kluwer Aca-
demic Publishers: Dordrecht, The Netherlands, 1992; Tables 4.2.6.8
and 6.1.1.4.
(14) Sheldrick, G. M. SHELXS97. A Program for Crystal Structure
Refinement; University of Gottingen: Germany, 1997.
(15) J ohnson, C. K. ORTEPII, Report ORNL-5138; Oak Ridge
National Laboratory: Oakridge, TN, 1976.