Zirconium complexes of diamine-bis(phenolate) ligands: Synthesis, structures, and solution dynamics

Article abstract of DOI:10.1021/om010982w

A study was performed on the synthesis, structures and solution dynamics of zirconium complexes of diamine-bis(phenolate) ligands. A series of six- or eight-coordinate derivatives were prepared and crystallographically characterized. It was found that attempts to generate catalytically active systems for the polymerization of ethylene were unsuccessful, although THF-stabilized benzyl cations were identified.

Full text of DOI:10.1021/om010982w

Organometallics 2002, 21, 1367-1382
1367
Zir con iu m Com p lexes of Dia m in e-Bis(p h en ola te)
Liga n d s: Syn th esis, Str u ctu r es, a n d Solu tion Dyn a m ics
Thierry Toupance, Stuart R. Dubberley, Nicholas H. Rees, Ben R. Tyrrell, and
Philip Mountford*
Inorganic Chemistry Laboratory, University of Oxford, South Parks Road,
Oxford OX1 3QR, U.K.
Received November 14, 2001
A family of new organometallic and coordination compounds supported by the diamine-
bis(phenolate) ligands O2NN′Me and O2NN′tBu are reported [H2O2NN′R ) (2-C5H4N)CH2N-
t
(CH2-2-HO-3,5-C6H2R2)2, where R ) Me (1a ) or Bu (1b)]. Reaction of H2O2NN′R with sodium
t
hydride in THF gives the corresponding sodium salts Na2O2NN′R (R ) Me (2a ) or Bu (2b)).
Reaction of H2O2NN′R with Zr(CH2SiMe3)2Cl2(Et2O)2 gives the cis-dichloride derivatives
t
ZrCl2(O2NN′R) (R ) Me (3a ) or Bu (3b)), which exist as two isomers (possessing either C1
(major) or Cs symmetry) in dynamic equilibrium with each other in solution. The compound
3b can also be prepared from Na2O2NN′tBu and ZrCl4(THF)2, but reaction of Na2O2NN′Me
with either ZrCl4 in benzene or ZrCl4(THF)2 in THF gives mixtures of 3a and the eight-
coordinate bis(diamine-bis(phenolate)) complex Zr(O2NN′Me)2 (4a ). The latter can also be
prepared from 2 equiv of H2O2NN′Me and Zr(CH2SiMe3)4. Treatment of Zr(NMe2)4 with H2O2-
NN′tBu leads to the bis(dimethylamide) derivative Zr(NMe2)2(O2NN′tBu) (5b). Similar proto-
nolysis reactions between ZrR′4 (R′ ) CH2SiMe3, CH2CMe3, or CH2Ph) give the corresponding
organometallic alkyl or benzyl compounds ZrR′2(O2NN′R) [R′ ) CH2SiMe3 (8a , 8b), CH2-
t
CMe3 (9a , 9b), or CH2Ph (10a , 10b); R ) Me (suffix a ) or Bu (suffix b)]. The dichloride
complexes ZrCl2(O2NN′R) (3a , 3b) are also precursors to new organometallic derivatives,
and treatment with LiR′ (R′ ) Me or CH2SiMe3) or R′MgCl (R′ ) CH2Ph or C3H5) yields
ZrR′2(O2NN′R) [R′ ) Me (6a , 6b), η3-C3H5 (7b), CH2SiMe3 (8a , 8b), CH2Ph (10a , 10b)]. The
thermally unstable bis(η3-allyl) complex 7b is highly fluxional in solution. Reaction of the
dibenzyl compound 10a or 10b with B(C6F5)3 in the presence of THF gives the cationic
complexes [Zr(CH2Ph)(THF)(O2NN′R)]+ as the [PhCH2B(C6F5)3]- salts (11a , 11b). The X-ray
crystal structures of the compounds 3a , 3b, 4a , 5b, 6a , 6b, and 10a are described.
In tr od u ction
sets from the groups of Floriani,11,12 Jordan,13-16 Scott,17,18
Coates,19 Fujita,20,21 Kol and Goldberg,22-24 and others.25
Following on from the historical dominance of met-
allocene and other cyclopentadienyl-based complexes in
the development of group 4 organometallic chemistry1
have been intense recent efforts to expand the repertoire
of new dianionic supporting ligand sets. Many new
systems have been described over the past 10 years in
particular2-9 in the drive for both fundamental new
chemistry and potential applications in, for example,
polymerization catalysis.10 Of particular relevance to the
new chemistry reported in this contribution are the
recent developments in group 4 organometallic and
catalytic chemistry with dianionic {N2O2} donor ligand
(11) Floriani, C.; Mazzanti, M.; Chiesi-Villa, A.; Guastini, C. J .
Chem. Soc., Dalton Trans. 1988, 1361.
(12) Solari, E.; Maltese, C.; Franceschi, F.; Floriani, C.; Chiesi-Villa,
A.; Rizzoli, C. J . Chem. Soc., Dalton Trans. 1997, 2903.
(13) Bei, X.; Swenson, D. C.; J ordan, R. F. Organometallics 1997,
16, 3282.
(14) Tsukahara, T.; Swenson, D. C.; J ordan, R. F. Organometallics
1997, 16, 3303.
(15) Kim, I.; Nishihara, Y.; J ordan, R. F.; Rogers, R. D.; Rheingold,
A. L.; Yap, G. P. A. Organometallics 1997, 16, 3314.
(16) Tjaden, E. B.; Swenson, D. C.; J ordan, R. F.; Petersen, J . L.
Organometallics 1995, 14, 371.
(17) Woodman, P. R.; Munslow, I. J .; Hitchcock, P. B.; Scott, P. J .
Chem. Soc., Dalton Trans. 1999, 4069.
(18) Woodman, P. R.; Alcock, N. W.; Munslow, I. J .; Sanders, C. J .;
Scott, P. J . Chem. Soc., Dalton Trans. 2000, 3340.
(19) Tian, J .; Hustad, P. D.; Coates, G. W. J . Am. Chem. Soc. 2001,
123, 5134.
(20) Saito, J .; Mitani, M.; Mohri, J .; Yoshida, Y.; Matsui, S.; Ischii,
S.; Kojoh, S.; Kashiwa, N.; Fujita, T. Angew. Chem., Int. Ed. 2001, 39,
2918.
* Corresponding author. E-mail: philip.mountford@chemistry.ox-
ford.ac.uk. Fax: +44 1865 272690.
(1) Metallocenes: Synthesis, Reactivity, Applications; Togni, A.,
Halterman, R. L., Eds.; Wiley-VCH: New York, 1998; Vol. 1 & 2, and
references therein.
(2) Gade, L. H. Chem. Commun. 2000, 173.
(3) Brand, H.; Arnold, J . Coord. Chem. Rev. 1995, 140, 137.
(4) Mountford, P. Chem. Soc. Rev. 1998, 27, 105.
(5) Schrock, R. R. Acc. Chem. Res. 1997, 30, 9.
(6) Gade, L. H.; Mountford, P. Coord. Chem. Rev. 2001, 216-217,
65.
(7) Wigley, D. E. Prog. Inorg. Chem. 1994, 42, 239.
(8) Mountford, P. Chem. Commun. 1997, 2127.
(9) Floriani, C.; Floriani-Moro, R. Adv. Organomet. Chem. 2001, 47,
167.
(21) Matsui, S.; Mitani, M.; Saito, J .; Tohi, Y.; Makio, H.; Mat-
sukawa, N.; Takagi, Y.; Tsuru, K.; Nitabaru, M.; Nakano, T.; Tanaka,
H.; Kashiwa, N.; Fujita, T. J . Am. Chem. Soc. 2001, 123, 6847.
(22) Tshuva, E. T.; Goldberg, I.; Kol, M.; Goldschmidt, Z. Organo-
metallics 2001, 20, 3017.
(23) Tshuva, E. T.; Goldberg, I.; Kol, M.; Goldschmidt, Z. Inorg.
Chem. 2001, 40, 4263.
(24) Tshuva, E. T.; Goldberg, I.; Kol, M. J . Am. Chem. Soc. 2000,
122, 10706.
(25) Repo, T.; Klinga, M.; Pietika¨¨ınen, P.; Leskela¨, M.; Uusitalo, A.-
M.; Pakkanen, T.; Hakala, K.; Aaltonen, P.; Lo¨fgren, B. Macromolecules
1997, 30, 171.
(10) Britovsek, G. J . P.; Gibson, V. C.; Wass, D. F. Angew. Chem.,
Int. Ed. 1999, 38, 429.
10.1021/om010982w CCC: $22.00 © 2002 American Chemical Society
Publication on Web 02/28/2002

1368 Organometallics, Vol. 21, No. 7, 2002
Toupance et al.
Ch a r t 1
Exp er im en ta l Section
Gen er a l Meth od s a n d In str u m en ta tion . All manipula-
tions of air- and/or moisture-sensitive compounds were carried
out using standard Schlenk line or drybox techniques under
an atmosphere of argon or dinitrogen. Solvents used with air-
and/or moisture-sensitive compounds were predried over
activated 4 Å molecular sieves and were refluxed over potas-
sium (THF, hexane, or benzene), sodium (toluene), sodium/
potassium alloy (pentane), sodium dispersion/benzophenone
(diethyl ether), or calcium hydride (dichloromethane) under a
dinitrogen atmosphere and collected by distillation. Deuterated
solvents for air- and/or moisture-sensitive compounds were
dried over potassium (C6D6) or calcium hydride (CD2Cl2 and
C5D5N), distilled under reduced pressure, and stored under
dinitrogen in ampules fitted with J . Young Teflon valves. NMR
samples of air- and/or moisture-sensitive compounds were
prepared under dinitrogen in 5 mm Wilmad 507-PP tubes
fitted with J . Young Teflon valves. All other solvents and
reagents were used as received from commercial suppliers.
1H and 13C{1H} NMR spectra were recorded on Varian
Venus 300 or Varian Unity Plus 500 spectrometers. 1H and
13C assignments were confirmed when necessary with the use
of one-dimensional NOE experiments and of two-dimensional
1H-1H COSY, 1H-1H NOESY, 13C-1H HSQC, and HMBC
NMR experiments. All spectra were referenced internally to
residual protio-solvent (1H) or solvent (13C) resonances and are
reported relative to trimethylsilane (δ ) 0 ppm). Chemical
shifts are quoted in δ (ppm); coupling constants, in hertz.
Infrared spectra were prepared as Nujol mulls between KBr
plates and were recorded on a Perkin-Elmer 1710 FTIR
spectrometer. Infrared data are quoted in wavenumbers
(cm-1), “vs” stands for very strong, “s” for strong, “m” for
medium, “w” for weak, and “vw” for very weak.
Mass spectra were recorded on an AEI MS 902 or Micomass
Autospec 500 mass spectrometer. Elemental analyses were
carried out by the analytical services of the University of
Oxford’s Inorganic Chemistry Laboratory.
Liter a tu r e P r ep a r a tion s. The compounds H2O2NN′tBu
(1b ),28 ZrCl4(THF)2,30 Zr(CH2SiMe3)2Cl2(Et2O)2,31 Zr(CH2-
SiMe3)4,32 Zr(CH2CMe3)4,33 and Zr(CH2Ph)434,35 were prepared
according to previously reported procedures.
In our group we have been developing new diamine-
bis(amide) ligands of the type (2-C5H4N)CH2N(CH2CH2-
NSiMe2R)2 (abbreviated as N2NN′, where R ) Me or
tBu).26 These dianionic, tetradentate ligands proved to
be useful supporting environments for early transition
metal, six- and five-coordinate complexes of the general
type M(A)(B)(N2NN′) and M(A)(N2NN′) (I, Chart 1). We
have developed in parallel studies the diamine-bis-
(alkoxide) ligand (2-C5H4N)CH2N(CH2CMe2O)2 and have
reported some new titanium and zirconium coordination
and organometallic complexes of the type II in Chart
1.26,27 Recently we have extended these studies to
include complexes of the diamine-bis(phenoxide) ligands
O2NN′Me and O2NN′tBu [H2O2NN′R ) (2-C5H4N)CH2N-
(CH2-2-HO-3,5-C6H2R2)2, where R ) Me (1a ) or tBu
(1b);28 see Chart 1]. The more sterically demanding
ligand O2NN′tBu supports new scandium and yttrium
coordination and organometallic complexes of the type
III in Chart 1.27,29 We were also interested to extend
these ligands to other transition metals. Here we
describe new organometallic and coordination chemistry
of zirconium supported by diamine-bis(phenolate)
ligands. The new compounds include cis-dichloride, bis-
(dimethylamide), dimethyl, bis(η3-allyl), bis(trimethyl-
silylmethyl), bis(neopentyl), and dibenzyl derivatives.
Syn th eses. To clarify the NMR chemical shift assignments,
diagrams showing a concise atom-labeling scheme accompany
each new type of ligand or complex.
(30) Manzer, L. E. Inorg. Synth. 1982, 21, 135.
(31) Brand, H.; Capriotti, J . A.; Arnold, J . Organometallics 1994,
13, 4469.
(26) Skinner, M. E. G.; Cowhig, D. A.; Mountford, P. Chem. Com-
mun. 2000, 1167.
(32) Collier, M. R.; Lappert, M. F. J . Chem. Soc., Dalton Trans. 1973,
445.
(27) Cowhig, D. A.; Li, Y.; Skinner, M. E. G.; Dubberley, S. R.;
Mountford, P. Unpublished results.
(28) Shimazaki, Y.; Huth, S.; Odani, A.; Yamauchi, O. Angew. Chem.,
Int. Ed. 2000, 39, 1666.
(33) Davidson, P. J .; Lappert, M. F.; Pearce, R. J . Organomet. Chem.
1973, 57, 269.
(34) Zucchini, U.; Aldizzati, E.; Giannini, U. J . Organomet. Chem.
1971, 26, 537.
(29) Skinner, M. E. G.; Tyrrell, B. R.; Ward, B. D.; Mountford, P. J .
Organomet. Chem., in press.
(35) Felten, J . J .; Anderson, W. P. J . Organomet. Chem. 1972, 36,
87.

Zirconium Complexes of Diamine Ligands
Organometallics, Vol. 21, No. 7, 2002 1369
N-(2-P yr id ylm et h yl)-N,N-b is(2′-h yd r oxy-3′,5′-d im et h -
ylben zyl)a m in e (H 2O2NN′Me, 1a ). 2-Aminomethylpyridine
(2.70 g, 24.9 mmol), 2,4-dimethylphenol (6.10 g, 49.9 mmol),
and paraformaldehyde (1.50 g, 49.9 mmol) were dissolved in
absolute ethanol (50 mL) in a thick-walled ampule equipped
with a Rotaflo valve. The mixture was stirred at 110 °C for 3
days. The volatiles were subsequently removed under reduced
pressure to leave an orange oil. This oil was triturated with
30 mL of absolute ethanol to yield a white powder, which was
isolated by filtration and drying. Yield: 4.80 g (51%).
Anal. Found (Calcd for C36H50N2O2Na2): C 72.68 (73.44), H
8.36 (8.56), N 4.69 (4.76), Na 7.38 (7.81).
1H NMR (300.18 MHz, CDCl3, 293 K): δ 10.42 (s, 2H, OH),
8.69 (d, 3J H1-H2 ) 5.8 Hz, 1H, H1), 7.68 (ddd, 3J H3-H4 ) 8.2 Hz,
4
3
3J H3-H2 ) 7.0 Hz, J H3-H1 ) 1.8 Hz, 1H, H3), 6.26 (dd, J H2-H1
) 5.8 Hz, 3J H2-H3 ) 7.0 Hz, 1H, H2), 7.10 (d, 3J H4-H3‚ ) 8.2 Hz,
4
4
1H, H4), 6.90 (d, J H11-H9 ) 1.2 Hz, 2H, H11), 6.74 (d, J H9-H11
) 1.2 Hz, 2H, H9), 3.82 (s, 2H, H6), 3.74 (s, 4H, H7), 2.28 (s,
3H, H14), 2.21 (s, 3H, H15). 13C{1H} NMR (75.48 MHz, CDCl3,
293 K): δ 156.1 (C5), 153.1 (C13), 148.2 (C1), 137.4 (C3), 131.1
(C11), 128.4 (C9), 127.4 (C12), 125.4 (C10), 123.6 (C4), 122.4 (C2),
120.7 (C8), 56.4 (C7), 55.4 (C6), 20.3 (C15), 16.2 (C14). MS-EI
(m/z): 377 (50%) [MH]+, 243 (70%) [MH - CH2(C6H2-
(CH3)2O)]+. Anal. Found (Calcd for C24H28N2O2): C 76.55
(76.56), H 7.40 (7.50), N 7.52 (7.44).
N-(2-P yr id ylm eth yl)-N,N-bis(2′-oxo-3′,5′-d im eth ylben -
zylsod iu m )a m in e (Na 2O2NN′Me, 2a ). A solution of H2O2-
NN′Me (1.51 g, 4 mmol) in THF (20 mL) was added dropwise
to a NaH suspension (0.388 g, 16.1 mmol) in THF (20 mL) at
-80 °C. Upon progressive return to room temperature, a gas
was evolved and the stirring at room temperature was
continued for 2 h. The mixture was then filtered and the
solvent was removed under reduce pressure to give a bright
white powder after drying overnight under vacuum at 90 °C.
Yield: 1.51 g (88%). The THF content was determined by
Zr (O2NN′Me)2 (4a ). Meth od A. A suspension of ZrCl4 (0.13
g, 0.56 mmol) and Na2O2NN′Me (0.46 g, 1.16 mmol) in benzene
(40 mL) was stirred overnight at room temperature. After
filtration, the colorless solution obtained was concentrated
under reduced pressure. The crude product was extracted with
dichloromethane (20 mL), and the solution was allowed to
stand for 2 h. After evaporation of the solvent, the powder
obtained was recrystallized from toluene at -80 °C to give a
white powder after drying. Yield: 0.20 g (42%).
Meth od B. A solution of H2O2NN′Me (0.5 g, 1.33 mmol) in
benzene (15 mL) was added dropwise to Zr(CH2SiMe3)4 (0.302
g, 0.685 mmol) in benzene (15 mL) with cooling using an ice/
water bath. The mixture was then heated at 60 °C for 2 h.
After return to room temperature, the volatiles were removed
under reduced pressure. The same purification steps as in
method A gave a white powder. Yield: 0.25 g (44%). Crystals
suitable for X-ray diffraction study were grown by slow
careful integration of the 1H NMR spectrum.
evaporation of a benzene solution.
3
1H NMR (300.18 MHz, C5D5N, 293 K): δ 8.16 (d, J H1-H2
)
3
1H NMR (499.99 MHz, CD2Cl2, 293 K): δ 9.75 (d, J H1-H2
)
3
3
5.7 Hz, 1H, H1), 7.43 (ddd, 3J H3-H4 ) 7.8 Hz, 3J H3-H2 ) 7.5 Hz,
4.7 Hz, 1H, H1), 7.42 (dd, J H3-H4 ) 8.2 Hz, J H3-H2 ) 7.6 Hz,
1H, H3), 7.10 (d, 3J H4-H3 ) 8.2 Hz, 1H, H4), 7.08 (br s, 2H, H11),
6.87 (br s, 2H, H9), 6.74 (dd, J H2-H3‚ ) 7.6 Hz, J H2-H1 ) 4.7
Hz, 1H, H2), 3.82 (vbr s, 4H, H6 7,7′), 2.90 (vbr s, 2H, H7 or
4J H3-H1 ) 1.7 Hz, 1H, H3), 7.02 (dd, J H2-H1 ) 5.7 Hz, J H2-H3
3
3
3
3
3
) 7.5 Hz, 1H, H2), 6.81 (d, J H4-H3 ) 7.8 Hz, 1H, H4), 6.72 (d,
4J H11′-H9′ ) 2.2 Hz, 1H, H11′), 6.64 (d, J H9′-H11′ ) 2.2 Hz, 1H,
4
or
7′), 2.38 (s, 3H, H14), 2.34 (s, 3H, H15). 13C{1H} NMR (75.43
MHz, C5D5N, 293 K): δ 166.9 (C13), 161.0 (C5), 150.5 (C1), 137.7
(C3), 133.0 (C9), 132.3 (C11), 126.1 (C12), 125.3 (C4), 122.5 (C2),
119.4 (C10), 62.5 (C6), 61.2 (vbr,C7), 20.1 (C15), 19.8 (C14) (C8
not observed). IR (Nujol mull) ν (cm-1) 1608 (m), 1596 (m),
1570 (m), 1554 (m), 1312 (s), 1274 (m), 1212 (w), 1162 (m),
1114 (s), 1050 (w), 1002 (w), 988 (w), 978 (w), 952 (w), 912
(w), 860 (m), 792 (s), 770 (w), 756 (m), 692 (w), 668 (w), 638
(w), 620 (w), 594 (w), 574 (w), 506 (w), 480 (s). Anal. Found
(Calcd for C24H26N2O2Na2‚(THF)0.125): C 67.25 (67.12), H 5.99
(6.10), N 6.27 (6.52), Na 10.05 (10.70).
N-(2-P yr id ylm eth yl)-N,N-bis(2′-oxo-3′,5′-ter t-bu tylben -
zylsod iu m )a m in e (Na 2O2NN′tBu , 2b). 2b was produced by
a procedure analogous with that for Na2O2NN′Me, with H2O2-
NN′tBu (1.5 g, 2.75 mmol) and sodium hydride (0.265 g, 11.2
mmol). After drying, a white powder was obtained. Yield: 1.3
H9′), 6.51 (d, 4J H9-H11 ) 2.2 Hz, 1H, H9), 6.36 (d, 4J H11-H9 ) 2.2
2
Hz, 1H, H11), 4.84 (d, J H6-H6′ ) 15.0 Hz, 1H, H6or6′), 4.75 (d,
2J H7′′-H7′′′ ) 12.8 Hz, 1H, H7′′or7′′′), 3.91 (d, J H7-H7′ ) 12.2 Hz,
2
2
1H, H7or7′), 3.61 (d, J H6-H6′ ) 15.0 Hz, 1H, H6or6′), 3.10 (d,
2J H7′′-H7′′′ ) 12.8 Hz, 1H, H7′′or7′′′), 2.57 (d, J H7-H7′ ) 12.2 Hz,
2
1H, H7or7′), 2.15 (s, 3H, H14), 2.12 (s, 3H, H15′), 2.03 (s, 3H, H15),
1.42 (s, 3H, H14′). 13C{1H} NMR (125.74 MHz, CD2Cl2, 293 K):
δ 160.8 (C13′), 158.2 (C13), 157.2 (C5), 148.4 (C1), 137.1 (C3),
131.4 (C11′), 131.1 (C11), 127.9 (C9), 127,8 (C9′), 125.1 (C12′), 125.0
(C10′), 124.9 (C8), 124.8 and 124.75 (C10 and C12), 124.2 (C8′),
121.8 (C2), 120.8 (C4), 65.9 (C6), 64.1 (C7′′), 60.3 (C7), 20.5 (C15′),
20.3 (C15), 18.4 (C14), 16.6 (C14′). IR (Nujol mull) ν (cm-1): 1606
(m), 1574 (w), 1418 (w), 1344 (w), 1324 (w), 1292 (m), 1222
(w), 1076 (w), 1054 (m), 990 (w), 960 (m), 859 (m), 826 (m),
810 (s), 756 (m), 730 (m), 696 (m), 640(w), 632 (w), 594 (w),
532 (m), 504 (m). MS-EI (m/z): 838 (20%) [M]+, 746 (100%)
[M - CH2C5H4N]+, 703 (70%) [M - CH2(C6H2(CH3)2O)]+, 612
(100%) [M - CH2C5H4N - CH2(C6H2(CH3)2O)]+. Anal. Found
(Calcd for C48H52N4O4Zr‚(C6H6)0.25): C 69.06 (69.15), H 6.35
(6.27), N 6.37 (6.51).
g (80%).
3
1H NMR (300.18 MHz, C5D5N, 293 K): δ 7.61 (d, J H1-H2
)
4.5 Hz, 1H, H1), 7.37 (ddd, 3J H3-H4 ) 7.7 Hz, 3J H3-H2 ) 7.4 Hz,
4J H3-H1 ) 1.9 Hz, 1H, H3), 7.32 (d, 4J H11-H9 ) 2.7 Hz, 2H, H11),
Zr Cl2(O2NN′Me) (3a ). A solution of H2O2NN′Me (1.17 g, 3.1
mmol) in benzene (25 mL) was added dropwise to ZrCl2(CH2-
SiMe3)2‚(Et2O)2 (1.5 g, 3.1 mmol) in benzene (30 mL) with
cooling using an ice/water bath. The mixture was allowed to
warm to room temperature and stirred overnight. A strong
white precipitate progressively appeared. The supernatant was
removed, and the resulting powder was washed twice with 50
mL of pentane. After drying in a vacuum, the crude product
was extracted into 80 mL of dichloromethane. Filtration and
evaporation of the solvent gave a white powder. Yield: 1.15 g
(69%). The NMR data at 213 K are consistent with the
presence of two isomers of C1 and Cs symmetry in the ratio
3
4
7.19 (d, J H4-H3‚ ) 7.7 Hz, 1H, H4), 6.98 (d, J H9-H11 ) 2.7 Hz,
2H, H9), 6.63 (dd, 3J H2-H1 ) 4.5 Hz, 3J H2-H3 ) 7.4 Hz, 1H, H2),
4.71 (br s, 2H, H7or7′), 4.14 (s, 2H, H6), 3.39 (br s, 2H, H7or7′),
1.63 (s, 18H, H15), 1.33 (s, 18H, H17). 13C{1H} NMR (75.43 MHz,
C5D5N, 293 K): δ 168.9 (C13), 162.2 (C5), 149.1 (C1), 137.0 (C3),
136.7 (C12), 126.95 and 126.9 (C8 and C9), 123.5 (C4), 123.0
(C11), 121.6 (C2), 66.1 (C7or7′), 62.8 (C6), 36.1 (C14), 34.3 (C16),
32.9 (C17), 30.7 (C15). IR (Nujol mull) ν (cm-1) 1598 (s), 1572
(m), 1414 (w), 1361 (w), 1317 (s), 1233 (m), 1201 (m), 1160
(m), 1133 (vw), 1117 (w), 1090 (m), 1054 (w), 1005 (m), 987
(w), 932 (w), 907 (w), 864 (m), 829 (s), 794 (m), 750 (s), 735 (s),
683 (w), 660 (vw), 641 (m), 623 (w), 567 (w), 543 (w), 514 (m).

1370 Organometallics, Vol. 21, No. 7, 2002
Toupance et al.
95:5%, respectively. Slow evaporation of a THF solution
provided suitable crystals of the C1 symmetry isomer for X-ray
diffraction study.
0.84 mmol) in THF (20 mL) at -78 °C. The mixture was
allowed to warm to room temperature and stirred for a further
4 h. After filtration and evaporation of the solvent, the white
solids obtained were extracted into CH2Cl2 (25 mL). The
resulting solution was filtered, layered with 20 mL of hexane,
and allowed to stand for 2 h at room temperature to provide
colorless plates. Yield: 0.30 g (50%).
The NMR data at 213 K are consistent with the presence of
two isomers of C1 and Cs symmetry in the ratio 65:35%,
respectively. This ratio has hampered the assignment of the
phenyl ring and tert-butyl protons and, also, of the 13C
spectrum.
1H NMR (499.99 MHz, CD2Cl2, 213 K): δ 8.73 (Cs, d, 3J H1-H2
3
) 5.2 Hz, 1H, H1), 8.59 (C1, d, J H1-H2 ) 5.4 Hz, 1H, H1), 7.60
(C1, ddd, 3J H3-H4 ) 7.9 Hz, 3J H3-H2 ) 7.6 Hz, 4J H3-H1 ) 1.5 Hz,
3
3
1H, H3), 7.47 (Cs, ddd, J H3-H4 ) 8.0 Hz, J H3-H2 ) 7.4 Hz,
4J H3-H1 ) 1.7 Hz, 1H, H3), 7.26 (C1, d, 1H), 7.16 (C1, dd, 3J H2-H1
) 5.5 Hz, 3J H2-H3 ) 7.6 Hz, 1H, H2), 7.09 (Cs, dd, 3J H2-H1 ) 5.6
Hz, 3J H2-H3 ) 7.4 Hz, 1H, H2), 7.08-7.05 (m, 3H), 7.03 (d, 1H),
3
6.78 (m, 2H), 6.61 (Cs, d, J H4-H3 ) 8.0 Hz, 1H, H4), 5.02 (C1,
d, 2J H7′′-H7′′′ ) 13.5 Hz, 1H, H7′′or7′′′), 4.76 (Cs, d, 2J H7-H7′ ) 14.0
Hz, 2H, H7or7′), 4.73 (C1, d, 2J H6-H6′ ) 15.5 Hz, 1H, H6or6′), 3.94
2
(C1, d, J H6-H6′ ) 15.5 Hz, 1H, H6or6′), 3.93 (Cs, s, 4H, H6), 3.74
2
2
(C1, d, J H7-H7′ ) 13.1 Hz, 1H, H7or7′), 3.60 (Cs, d, J H7-H7′
)
14.0 Hz, 2H, H7or7′), 3.57 (C1, d, 2J H7′′-H7′′′ ) 13.5 Hz, 1H, H7or7′),
3.00 (C1, d, 2J H7-H7′ ) 13.1 Hz, 1H, H7or7′), 1.41 (s, 9H), 1.20 (s,
18H), 1.18 (s, 9H), 1.16 (s, 9H), 1.02 (s, 9H). 13C{1H} NMR
(75.48 MHz, CD2Cl2, 223 K): δ 157.5, 156.7, 156.1, 155.0, 150.7
(Cs, C1), 147.3 (C1, C1), 143.1, 142.3, 141.7, 140.4 (Cs and C1,
C3), 136.2, 135.7, 134.9, 125.5, 125.1, 124.6, 124.5, 124.2, 124.0,
123.9, 123.5, 123.4, 122.6, 121.4 (Cs, C4), 64.8 (C1, C6), 64.4
(Cs, C7), 64.0 (C1, C7′′), 60.8 (C1, C7), 58.8 (Cs, C6), 35.5, 35.3,
1H NMR (499.99 MHz, CD2Cl2, 213 K): C1 symmetry isomer:
δ 8.76 (d, 3J H1-H2 ) 5.2 Hz, 1H, H1), 7.63 (ddd, 3J H3-H4 ) 3J H3-H2
35.0, 34.9, 34.8, 34.5, 31.9, 31.8, 29.9. IR (Nujol mull): ν (cm-1
)
4
3
1606 (m), 1568 (vw), 1418 (w), 1362 (m), 1240 (m), 1202 (m),
1170 (m), 1128 (m), 1058 (w), 974 (w), 914 (w), 880 (w), 862
(m), 846 (m), 760 (s), 674 (w), 648 (w), 600 (w), 564 (m), 554
(m), 506 (w). MS-EI (m/z): 704 (M+, 100%), 668 (MH+ - Cl,
50%). Anal. Found (Calcd for C36H50Cl2N2O2Zr): C 61.12
(61.34), H 7.12 (7.15), N 3.80 (3.97).
Zr (NMe2)2(O2NN′tBu ) (5b). A solution of H2O2NN′tBu (0.30
g, 0.55 mmol) in benzene (20 mL) was added dropwise to Zr-
(NMe2)4 (0.15 g, 0.56 mmol) in benzene (20 mL) with cooling
using an ice/water bath. The mixture was allowed to warm to
room temperature and stirred for a further 2 h. The volatiles
were then removed under reduced pressure. The crude product
was washed with pentane (20 mL) to yield a white powder
after drying. Yield: 0.24 g (80%). Crystals suitable for X-ray
diffraction study were grown by slow evaporation of a benzene
) 7.8 Hz, J H3-H1 ) 1.7 Hz, 1H, H3), 7.21 (dd, J H2-H1 ) 5.2
3
3
Hz, J H2-H3 ) 7.8 Hz, 1H, H2), 7.00 (d, J H4-H3 ) 7.8 Hz, 1H,
H4), 6.99 (s, 1H, H11′), 6.90 (s, 1H, H9′), 6.60 (s, 1H, H9), 6.49
2
(d, 1H, H11), 4.97 (d, J H7′′-H7′′′ ) 13.4 Hz, 1H, H7′′or7′′′), 4.62 (d,
2J H6-H6′ ) 15.4 Hz, 1H, H6or6′), 3.82 (d, J H6-H6′ ) 15.4 Hz, 1H,
2
H
6or6′), 3.82 (d, 2J H7-H7′ ) 12.9 Hz, 1H, H7or7′), 3.55 (d, 2J H7′′-H7′′′
2
) 13.4 Hz, 1H, H7or7′), 2.97 (d, J H7-H7′ ) 12.9 Hz, 1H, H7or7′),
2.24 (s, 3H, H14′), 2.23 (s, 3H, H15′), 2.00 (s, 3H, H15), 1.84 (s,
3H, H14). Cs symmetry isomer: δ 8.82 (d, 3J H1-H2 ) 5.8 Hz, 1H,
3
3
4
H1), 7.48 (ddd, J H3-H4 ) 8.3 Hz, J H3-H2 ) 7.4 Hz, J H3-H1
)
3
3
1.7 Hz, 1H, H3), 7.11 (dd, J H2-H1 ) 5.8 Hz, J H2-H3 ) 7.4 Hz,
3
1H, H2), 6.82 (s, 2H, H11), 6.75 (s, 2H, H9), 6.57 (d, J H4-H3
)
8.3 Hz, 1H, H4), 4.74 (d, 2J H7-H7′ ) 13.4 Hz, 2H, H7or7′), 3.78 (s,
2
2H, H6), 3.53 (d, J H7-H7′ ) 13.4 Hz, 2H, H7or7′), 2.15 (s, 6H,
H
14), 1.96 (s, 6H, H15). 13C{1H} NMR (125.74 MHz, CD2Cl2,
solution.
233 K): C1 symmetry isomer: δ 156.0 (C13), 155.6 (C5), 153.9
(C13′), 146.0 (C1), 140.0 (C3), 131.6 (C11′), 131.4 (C11), 129.9 (C10′),
128.6 (C10), 127.8 (C9′), 127.1 (C9), 125.4 (C12′), 124.4 (C12), 123.3
(C2), 123.0 (C8), 122.7 (C8′), 122.2 (C4), 64.1 (C6), 63.4 (C7′′), 60.0
(C7), 20.4 (C15′), 20.1 (C15), 15.9(C14′), 15.3 (C14). IR (Nujol mull)
ν (cm-1): 1612 (m), 1570 (vw), 1346 (vw), 1326 (w), 1296 (w),
1244 (s), 1220 (m), 1162 (m), 1078 (w), 1058 (w), 1026 (w), 968
(vw), 960 (vw), 946 (w), 860 (s), 828 (s), 758 (m), 694 (vw), 648
(w), 632 (vw), 600 (m), 554 (m). MS-EI (m/z): 536 (85%) [M]+,
498 (100%) [M - Cl]+, 401 (100%) [M - CH2(C6H2(CH3)2O)]+.
Anal. Found (Calcd for C24H26Cl2N2O2Zr): C 53.43 (53.72), H
4.99 (4.88), N 4.97 (5.22).
3
1H NMR (300.18 MHz, C6D6, 293 K): δ 8.29 (d, J H1-H2
)
4
5.3 Hz, 1H, H1), 7.33 (d, J H11-H9 ) 3 Hz, 2H, H11), 6.91 (d,
4J H9-H11 ) 3 Hz, 2H, H9), 6.41 (ddd, J H3-H4 ) 7.6 Hz, J H3-H2
3
3
4
3
) 7.6 Hz, J H3-H1 ) 1.8 Hz, 1H, H3), 6.17 (dd, J H2-H1 ) 5.3
3
3
Hz, J H2-H3 ) 7.6 Hz, 1H, H2), 5.68 (d, J H4-H3 ) 7.6 Hz, 1H,
H4), 4.44 (d, 2J H7-H7′ ) 12.3 Hz, 2H, H7or7′), 3.63 (s, 6H, H19or18),
2
3.34 (s, 6H, H18or19), 3.16 (s, 2H, H6), 2.90 (d, J H7-H7′ ) 12.3
Hz, 2H, H7or7′), 1.60 (s, 18H, H15), 1.37 (s, 18H, H17). 13C{1H}
NMR (75.48 MHz, C6D6, 293 K): δ 159.2 (C13), 158.4 (C5), 149.7
(C1), 138.9 (C10), 137.2 (C3), 136.6 (C12), 125.1 (C9), 124.7 (C8),
123.8 (C11), 121.5 (C2), 120.9 (C4), 64.1 (C7), 57.5 (C6), 45.9
(C18or19), 44.7 (C19or18), 35.3 (C14), 34.2 (C16), 32.1 (C17), 30.1 (C15).
IR (Nujol mull): ν (cm-1) 1605 (m), 1414 (w), 1272 (s), 1240
(m), 1205 (w), 1170 (w), 1148 (w), 1137 (w), 1061 (w), 976 (w),
960 (m), 942 (m), 876 (m), 840 (m), 760 (m), 641(w), 631 (w),
544 (m). MS-EI (m/z) 720 (100%) [M]+. Anal. Found (Calcd for
C40H62N4O2Zr): 66.53; H, 8.65; N, 7.76. Found: C 66.18 (66.53),
H 8.74 (8.65), N 7.37 (7.76).
Zr Cl2(O2NN′tBu ) (3b). Meth od A. 3b was formed by a
procedure analogous with that for ZrCl2(O2NN′Me), with H2O2-
NN′tBu (1.65 g, 3.03 mmol) and ZrCl2(CH2SiMe3)2(Et2O)2 (1.45
g, 3.02 mmol) in benzene (50 mL). After stirring at room
temperature overnight, the supernatant was removed and the
resulting powder was washed twice with 60 mL of pentane.
After drying in a vacuum, the crude product was extracted
into 60 mL of dichloromethane. Filtration and evaporation of
the solvent gave a white powder. Yield: 1.35 g (63%).
Meth od B. A solution of Na2O2NN′tBu (0.50 g, 0.84 mmol)
in THF (20 mL) was added dropwise to ZrCl4(THF)2 (0.32 g,
Zr Me2(O2NN′Me) (6a ). Meth od A. A solution of MeLi 1.55
M in ether (0.75 mL, 1.16 mmol) was added dropwise to a
suspension of ZrCl2(O2NN′Me) (0.30 g, 0.56 mmol) in benzene
(25 mL) with cooling using an ice/water bath. The mixture was

Zirconium Complexes of Diamine Ligands
Organometallics, Vol. 21, No. 7, 2002 1371
EI (m/z): 495 (100%) [MH]+. HRMS-EI: Found (Calcd) 494.1049
[494.1511]. Anal. Found (Calcd for C26H32N2O2Zr): C 60.88
(62.99), H 6.80 (6.50), N 5.32 (5.60). (Despite repeated attempts
a satisfactory %C analysis could not be obtained for the
crystallographically characterized compound.)
Zr Me2(O2NN′tBu ) (6b). Meth od A. 6b was formed by a
procedure analogous with that for ZrMe2(O2NN′Me), with MeLi
(0.55 mL, 0.86 mmol) and ZrCl2(O2NN′tBu) (0.30 g, 0.43 mmol)
in benzene (20 mL). The volatiles were then removed under
reduced pressure. The crude product was extracted into ether
(10 mL). The resulting solution was filtered, layered with 10
mL of hexane, and cooled to -30 °C to yield a white powder
after drying. Yield: 0.12 g (42%). Crystals suitable for X-ray
diffraction study were grown by slow evaporation of an ether
solution.
Meth od B. 6b was formed by a procedure analogous with
that for ZrMe2(O2NN′Me), with MeMgBr (0.52 mL, 0.73 mmol)
and ZrCl2(O2NN′tBu) (0.25 g, 0.35 mmol) in THF (30 mL). After
addition of 1,4-dioxane (0.2 mL, 2.3 mmol) and solvent
evaporation, the solids were extracted into benzene (30 mL).
The resulting solution was filtered and concentrated to 2 mL,
and addition of 30 mL of pentane yielded a white powder.
Yield: 0.08 g (35%).
3
1H NMR (499.99 MHz, C6D6, 293 K): δ 8.19 (d, J H1-H2
)
4
5.6 Hz, 1H, H1), 7.36 (d, J H11-H9 ) 2.6 Hz, 2H, H11), 6.86 (d,
4J H9-H11 ) 2.6 Hz, 2H, H9), 6.32 (ddd, 3J H3-H4 ) 8.0 Hz, 3J H3-H2
4
3
) 7.6 Hz, J H3-H1 ) 1.7 Hz, 1H, H3), 6.05 (dd, J H2-H1 ) 5.6
3
3
Hz, J H2-H3 ) 7.6 Hz, 1H, H2), 5.56 (d, J H4-H3 ) 8.0 Hz, 1H,
2
H4), 4.07 (d, J H7-H7′ ) 12.9 Hz, 2H, H7or7′), 2.97 (s, 2H, H6),
2
2.65 (d, J H7-H7′ ) 12.9 Hz, 2H, H7or7′), 1.62 (s, 18H, H15), 1.34
(s, 18H, H17), 1.16 (s, 3H, H19), 0.88 (s, 3H, H18). 13C{1H} NMR
(75.48 MHz, C6D6, 293 K): δ 159.2 (C13), 158.7 (C5), 149.4 (C1),
140.1 (C10), 137.2 (C3), 136.5 (C12), 125.0 (C9), 124.7 (C8), 124.3
(C11), 121.6 (C2), 120.4 (C4), 63.3 (C7), 57.7 (C6), 41.1 (C19), 37.6
(C18), 35.4 (C14), 34.3 (C16), 32.0 (C17), 30.1 (C15). IR (Nujol
mull): ν (cm-1) 1602 (m), 1566 (w), 1420 (w), 1360 (m), 1268
(s), 1238 (m), 1202 (m), 1168 (m), 1128 (m), 1094 (w), 1054
(w), 1012 (w), 974 (m), 914 (m), 882 (m), 872 (w), 842 (s), 808
(m), 772 (w), 750 (s), 726 (s), 688 (w), 644(w), 630 (w), 614 (vw),
606 (w), 564 (vw), 548 (m), 510 (w). MS-EI (m/z): 649 (50%)
[M - CH3]+. Anal. Found (Calcd for C38H56N2O2Zr): C, 66.50
(68.78), H 8.52 (8.50), N 4.05 (4.22), (Despite repeated attempts
a satisfactory %C analysis could not be obtained for the
crystallographically characterized compound.)
Zr (η3-C3H5)2(O2NN′tBu ) (7b). A 1.73 M solution of C3H5-
MgCl in THF (0.5 mL, 0.42 mmol) was added dropwise to a
suspension of ZrCl2(O2NN′tBu) (0.292 g, 0.42 mmol) in benzene
(20 mL) with cooling using an ice/water bath. The mixture was
allowed to warm to room temperature and stirred for a further
2 h with exclusion of light. The volatiles were then removed
under reduced pressure. Yield: 0.13 g (42%). The instability
in solution of this compound has prevented us from obtaining
allowed to warm to room temperature and stirred for a further
2 h. The volatiles were then removed under reduced pressure.
The crude product was extracted into ether (10 mL). The
resulting solution was filtered and evaporated to dryness to
give a white powder. This was washed twice with 10 mL of
hexane, leading to a white powder after drying. Yield: 0.15 g
(54%). Crystals suitable for X-ray diffraction study were grown
by slow evaporation of an ether solution.
Meth od B. A solution of MeMgBr 1.4 M in toluene/THF
(3:1 v/v, 0.68 mL, 0.95 mmol) was added dropwise to a solution
of ZrCl2(O2NN′Me) (0.25 g, 0.47 mmol) in THF (25 mL) at -78
°C. The mixture was allowed to return to room temperature
and stirred for a further 2 h. Dry 1,4-dioxane (0.250 mL, 2.75
mmol) was added via microsyringe, and the mixture was
stirred for 20 min. After evaporation of the solvent, the solids
were extracted into ether (30 mL). The resulting solution was
filtered and concentrated to 5 mL, and 20 mL of pentane was
a good microanalysis.
3
1H NMR (499.99 MHz, C6D6, 293 K): δ 8.90 (d, J H1-H2
)
4
5.6 Hz, 1H, H1), 7.23 (d, J H11-H9 ) 2.4 Hz, 2H, H11), 7.09
3
(apparent quintet, apparent J H20-H21 ) 11 Hz, 1H, H20), 6.79
4
3
added to give a white powder. Yield: 0.07 g (30%).
(d, J H9-H11 ) 2.4 Hz, 2H, H9), 6.43 (ddd, J H3-H4 ) 7.8 Hz,
3
4
1H NMR (499.99 MHz, C6D6, 293 K): δ 8.18 (d, J H1-H2
)
3J H3-H2 ) 7.6 Hz, J H3-H1 ) 1.7 Hz, 1H, H3), 6.25 (apparent
3
5.4 Hz, 1H, H1), 6.71 (s, 2H, H11), 6.50 (s, 2H, H9), 6.30 (ddd,
quintet, apparent J H18-H19 ) 12.4 Hz, 1H, H18), 6.21 (dd,
3J H3-H4 ) 7.8 Hz, J H3-H2 ) 7.6 Hz, J H3-H1 ) 0.9 Hz, 1H, H3),
3J H2-H1 ) 5.6 Hz, 3J H2-H3 ) 7.6 Hz, 1H, H2), 5.79 (d, 3J H4-H3
)
3
4
3
3
2
6.01 (dd, J H2-H1 ) 5.4 Hz, J H2-H3 ) 7.6 Hz, 1H, H2), 5.54 (d,
7.8 Hz, 1H, H4), 4.51 (d, J H7-H7′ ) 13.2 Hz, 2H, H7or7′), 3.83
3J H4-H3 ) 7.8 Hz, 1H, H4), 4.11 (d, J H7-H7′ ) 12.9 Hz, 2H,
(br s, 4H, H21), 3.71 (d, J H19-H18 ) 13.2 Hz, 4H, H19), 3.17 (s,
2
2
2
2
H
7or7′), 2.97 (s, 2H, H6), 2.66 (d, J H7-H7′ ) 12.9 Hz, 2H, H7or7′),
2H, H6), 2.76 (d, J H7-H7′ ) 13.2 Hz, 2H, H7or7′), 1.35 (s, 18H,
2.26 (s, 6H, H14), 2.15 (s, 6H, H15), 1.11 (s, 3H, H19), 0.85 (s,
3H, H18). 13C{1H} NMR (125.74 MHz, C6D6, 293 K): δ 158.7
(C13), 158.3 (C5), 148.1 (C1), 137.2 (C3), 132.0 (C11), 128.2 (C9),
126.5 (C10), 125.8 (C12), 123.6 (C8), 121.8 (C2), 120.4 (C4), 62.7
(C7), 58.2 (C6), 38.6 (C19), 38.2 (C18), 20.6 (C15), 16.1 (C14). IR
(Nujol mull): ν (cm-1) 1604 (m), 1568 (vw), 1320 (w), 1308 (m),
1262 (s), 1218 (vw), 1158 (m), 1054 (w), 958 (w), 854 (m), 826
(s), 752 (m), 642 (w), 624 (w), 590 (m), 554 (m), 510 (w). MS-
H
15), 1.31 (s, 18H, H17). 13C{1H} NMR (75.48 MHz, C6D6, 293
K): δ 158.5 (C5), 158.3 (C13), 150.3 (C1), 145.8 (C20), 141.2 (C18),
140.0 (C10), 137.2 (C3), 136.3 (C12), 125.1 (C9), 124.6 (C8), 123.8
(C11), 122.0 (C2), 121.2 (C4), 81.3 (C19), 79.2 (vb, C21), 66.2 (C7),
60.9 (C6), 35.1 (C14), 34.2 (C16), 32.0 (C17), 30.2 (C15). IR (Nujol
mull): ν (cm-1) 1603 (w), 1599 (m), 1537 (w), 1572 (w), 1413
(w), 1320 (s), 1283 (w), 1263 (s), 1240 (m), 1204 (w), 1169 (m),
1132 (w), 1100 (w), 1018 (w), 974 (w), 914 (w), 870 (w), 840

1372 Organometallics, Vol. 21, No. 7, 2002
Toupance et al.
(s), 807 (m), 760 (m), 751 (m), 723 (m), 675 (w), 646 (w), 634
(vw), 595 (w), 547 (s), 504 (w).
volatiles were then removed under reduced pressure. The
crude product was extracted into pentane (20 mL). The
resulting solution was filtered, concentrated to 10 mL, and
cooled to -30 °C to yield a white powder after drying. Yield:
Zr (CH2SiMe3)2(O2NN′Me) (8a ). Meth od A. A solution of
H2O2NN′Me (0.34 g, 0.91 mmol) in benzene (20 mL) was added
dropwise to Zr(CH2SiMe3)4 (0.40 g, 0.91 mmol) in benzene (20
mL) with cooling using an ice/water bath. The mixture was
allowed to warm to room temperature and stirred for a further
2 h. The volatiles were subsequently removed under reduced
pressure, and the resulting solids were extracted into 80 mL
of dry pentane. The orange solution was filtered, concentrated
to 60 mL, and cooled to -30 °C to give a yellowish crystalline
solid. Yield: 0.36 g (62%).
0.10 g (40%).
3
1H NMR (499.99 MHz, C6D6, 293 K): δ 8.54 (d, J H1-H2
)
4
5.3 Hz, 1H, H1), 6.70 (d, J H11-H9 ) 1.5 Hz, 2H, H11), 6.51 (d,
4J H9-H11 ) 1.5 Hz, 2H, H9), 6.35 (ddd, J H3-H4 ) 3J H3-H2 ) 7.6
3
4
3
Hz, J H3-H1 ) 1.8 Hz, 1H, H3), 6.12 (dd, J H2-H1 ) 5.3 Hz,
3J H2-H3 ) 7.6 Hz, 1H, H2), 5.60 (d, J H4-H3 ) 7.6 Hz, 1H, H4),
3
2
4.38 (d, J H7-H7′ ) 12.9 Hz, 2H, H7or7′), 3.04 (s, 2H, H6), 2.72
2
(d, J H7-H7′ ) 12.9 Hz, 2H, H7or7′), 2.34 (s, 6H, H14), 2.17 (s,
6H, H15), 1.92 (s, 2H, H21), 1.67 (s, 9H, H23), 1.45 (s, 11H, H18
and H20). 13C{1H} NMR (75.48 MHz, C6D6, 293 K): δ 158.7
(C13), 158.4 (C5), 148.6 (C1), 137.1 (C3), 132.1 (C11), 128.5 (C9),
126.6 (C10), 125.9 (C12), 123.8 (C8), 121.5 (C2), 120.8 (C4), 85.6
(C21), 84.5 (C18), 63.4 (C7), 58.9 (C6), 35.6 (C23), 35.4 (C20), 35.1
Meth od B (NMR tube scale). At room temperature, a
solution of LiCH2SiMe3 (5.3 mg, 55.6 µmol) in C6D6 (1 mL) was
added to ZrCl2(O2NN′Me) (14.9 mg, 27.8 µmol). The latter
progressively dissolved, and a slightly cloudy solution was
obtained after 5 min. After filtration, the 1H NMR spectrum
(C22), 35.0 (C19), 20.6 (C15), 17.2 (C14). IR (Nujol mull): ν (cm-1
)
indicated the formation of pure 8a .
3
1H NMR (300.18 MHz, C6D6, 293 K): δ 8.30 (d, J H1-H2
)
1604 (m), 1570 (w), 1354 (w), 1322 (w), 1230 (w), 1218 (w),
1054 (w), 1012 (w), 960(m), 902 (w), 856 (m), 824 (s), 756 (m),
728 (m), 640 (w), 624 (w), 588 (m), 552 (m), 518 (w). Anal.
Found (Calcd for C34H48N2O2Zr‚(C5H12)0.60): C 68.53 (68.24),
H 7.18 (7.54), N 4.49 (4.30).
Zr (CH2CMe3)2(O2NN′tBu ) (9b). 9b was formed by a proce-
dure analogous with that for Zr(CH2CMe3)2(O2NN′Me), with
H2O2NN′tBu (0.214 g, 0.392 mmol) and Zr(CH2CMe3)4 (0.15 g,
0.393 mmol) in benzene (30 mL). After evaporation of the
volatiles, the crude product was washed with 30 mL of dry
4
5.5 Hz, 1H, H1), 6.71 (d, J H11-H9 ) 1.5 Hz, 2H, H11), 6.50 (d,
4J H9-H11 ) 1.5 Hz, 2H, H9), 6.34 (ddd, 3J H3-H4 ) 8.0 Hz, 3J H3-H2
4
3
) 7.5 Hz, J H3-H1 ) 1.8 Hz, 1H, H3), 6.10 (dd, J H2-H1 ) 5.5
3
3
Hz, J H2-H3 ) 7.5 Hz, 1H, H2), 5.57 (d, J H4-H3 ) 8.0 Hz, 1H,
2
H4), 4.21 (d, J H7-H7′ ) 13.2 Hz, 2H, H7or7′), 3.00 (s, 2H, H6),
2
2.73 (d, J H7-H7′ ) 13.2 Hz, 2H, H7or7′), 2.33 (s, 6H, H14), 2.17
(s, 6H, H15), 1.14 (s, 2H, H20), 0.95 (s, 2H, H18), 0.62 (s, 9H,
H
21), 0.23 (s, 9H, H19). 13C{1H} NMR (75.48 MHz, C6D6, 293
K): δ 158.5 (C13), 158.0 (C5), 148.0 (C1), 137.1 (C3), 132.0 (C11),
128.1 (C9), 126.6 (C10), 125.7 (C12), 123.4 (C8), 121.5 (C2), 120.6
(C4), 63.0 (C7), 58.4 (C6), 54.4 (C18), 53.7 (C20), 20.5 (C15), 16.8
(C14), 3.7 (C21), 3.1 (C19). IR (Nujol mull): ν (cm-1) 1604 (m),
1320 (w), 1161 (m), 1059 (w), 1013 (w), 859 (m), 823 (s), 751-
(m), 677 (w), 640(w), 624 (w), 588 (m), 552 (m), 520 (m). MS-
EI (m/z): 625 (15%) [M - CH3]+. Anal. Found (Calcd for
pentane to give a white powder. Yield: 0.15 g (49%).
3
1H NMR (499.99 MHz, C6D6, 293 K): δ 8.44 (d, J H1-H2
)
4
4.5 Hz, 1H, H1), 7.38 (d, J H11-H9 ) 2.5 Hz, 2H, H11), 6.94 (d,
4J H9-H11 ) 2.5 Hz, 2H, H9), 6.31 (ddd, 3J H3-H4 ) 7.7 Hz, 3J H3-H2
4
3
) 7.4 Hz, J H3-H1 ) 1.7 Hz, 1H, H3), 6.11 (dd, J H2-H1 ) 4.5
3
3
Hz, J H2-H3 ) 7.4 Hz, 1H, H2), 5.57 (d, J H4-H3 ) 7.7 Hz, 1H,
2
C
32H48N2O2Si2Zr): C 58.95 (60.04), H 7.73 (7.56), N 4.23 (4.38).
H4), 4.61 (d, J H7-H7′ ) 12.8 Hz, 2H, H7or7′), 3.05 (s, 2H, H6),
2
The low %C found for this compound and its homologue 8b
may be due to incomplete combustion and carbide formation.
Zr (CH2SiMe3)2(O2NN′tBu ) (8b). Meth od A. 8b was formed
by a procedure analogous with that for Zr(CH2SiMe3)2(O2-
NN′Me), with H2O2NN′tBu (0.375 g, 0.69 mmol) and Zr(CH2-
SiMe3)4 (0.305 g, 0.69 mmol) in benzene (20 mL). After
evaporation of the volatiles, the crude product was washed
with 30 mL of dry pentane to give a white powder. Yield: 0.40
g (71%).
2.83 (d, J H7-H7′ ) 12.8 Hz, 2H, H7or7′), 1.81 (s, 2H, H21), 1.72
(s, 9H, H23), 1.70 (s, 2H, H18), 1.65 (s, 18H, H15), 1.39 (s, 9H,
H
20), 1.37 (s, 18H, H17). 13C{1H} NMR (75.48 MHz, C6D6, 293
K): δ 159.0 (C13), 158.8 (C5), 149.3 (C1), 140.0 (C10), 137.1 (C3),
136.7 (C12), 125.3 (C9), 125.1 (C8), 124.4 (C11), 121.5 (C2), 120.5
(C4), 96.0 (C18), 83.1 (C21), 63.9 (C7), 57.9 (C6), 36.4, 36.1, 35.7,
35.4 (C14), 35.2, 34.3 (C16), 32.0 (C17), 30.5 (C15). IR (Nujol
mull): ν (cm-1) 1604 (m), 1568 (w), 1414 (w), 1364 (w), 1290
(w), 1238 (m), 1202 (m), 1168 (w), 1130 (w), 1058 (w), 1010
(w), 932 (w), 912 (w), 878 (m), 854 (m), 772 (w), 760 (s), 750
(m), 676 (w), 644 (w), 628 (w), 600 (w), 564 (s), 546 (m). Anal.
Found (Calcd for C46H72N2O2Zr): C, 71.21 (71.17), H 10.95
(9.35), N 3.33 (3.61).
Zr (CH2C6H5)2(O2NN′Me) (10a ). Meth od A. A solution of
H2O2NN′Me (0.195 g, 0.52 mmol) in benzene (15 mL) was added
dropwise to Zr(CH2C6H5)4 (0.247 g, 0.54 mmol) in benzene (15
mL) with cooling using an ice/water bath. The mixture was
allowed to warm to room temperature and stirred for a further
2 h with exclusion of light. The volatiles were then removed
under reduced pressure. The crude product was extracted into
ether (20 mL). The resulting solution was filtered and cooled
to -30 °C to yield yellow plates after drying. Yield: 0.15 g
(45%). Crystals suitable for X-ray diffraction study were grown
from a saturated ether solution at -30 °C.
Meth od B (NMR tube scale). 8b was formed by a procedure
analogous with that for Zr(CH2SiMe3)2(O2NN′Me), with LiCH2-
SiMe3 (4.2 mg, 44 µmol) in C6D6 (1 mL) and ZrCl2(O2NN′tBu
)
(15.1 mg, 21.4 µmol).
3
1H NMR (300.18 MHz, C6D6, 293 K): δ 8.26 (d, J H1-H2
)
4
5.4 Hz, 1H, H1), 7.36 (d, J H11-H9 ) 2.4 Hz, 2H, H11), 6.94 (d,
4J H9-H11 ) 2.4 Hz, 2H, H9), 6.29 (ddd, 3J H3-H4 ) 7.8 Hz, 3J H3-H2
4
3
) 7.6 Hz, J H3-H1 ) 1.7 Hz, 1H, H3), 6.03 (dd, J H2-H1 ) 5.4
3
3
Hz, J H2-H3 ) 7.6 Hz, 1H, H2), 5.54 (d, J H4-H3 ) 7.8 Hz, 1H,
2
H4), 4.51 (d, J H7-H7′ ) 12.8 Hz, 2H, H7or7′), 3.01 (s, 2H, H6),
2
2.87 (d, J H7-H7′ ) 12.8 Hz, 2H, H7or7′), 1.59 (s, 18H, H15), 1.31
(s, 18H, H17), 1.14 (s, 2H, H20), 0.95 (s, 2H, H18), 0.62 (s, 9H,
H
21), 0.23 (s, 9H, H19). 13C{1H} NMR (75.48 MHz, C6D6, 293
K): δ 159.0 (C13), 158.8 (C5), 149.5 (C1), 140.2 (C10), 137.2 (C3),
136.6 (C12), 125.1 (C9), 124.8 (C8), 124.5 (C11), 121.5 (C2), 120.4
(C4), 63.3 (C7), 61.7 (C18), 57.7 (C6), 52.2 (C20), 35.4 (C14), 34.3
(C16), 32.0 (C17), 30.4 (C15), 3.6 (C21), 3.3 (C19). IR (Nujol mull):
ν (cm-1) 1605 (m), 1413 (w), 1242 (m), 1201 (w), 1169 (w), 1131
(w), 1059 (w), 974 (w), 916 (m), 898 (m), 846 (m), 762 (w), 750
(w), 676 (w), 629 (w), 549 (m). MS-EI (m/z): 794 (35%) [MH -
CH3]+. Anal. Found (Calcd for C44H72N2O2Si2Zr): C 64.63
(65.37), H 9.15 (8.98), N 3.32 (3.47).
Zr (CH2CMe3)2(O2NN′Me) (9a ). A solution of H2O2NN′Me
(0.15 g, 0.40 mmol) in benzene (15 mL) was added dropwise
to Zr(CH2CCMe3)4 (0.15 g, 0.40 mmol) in benzene (15 mL) with
cooling using an ice/water bath. The mixture was allowed to
warm to room temperature and stirred for a further 2 h. The
Meth od B (NMR tube scale). At room temperature, C6H5-
CH2MgCl 1.25 M in ether (46 µL, 57 mmol) was added via
microsyringe to a suspension of ZrCl2(O2NN′Me) (15.3 mg, 28.5
µmol) in C6D6 (1 mL). The latter progressively dissolved, and
a slightly cloudy solution was obtained after 10 min. After
filtration, the 1H NMR spectrum indicated the formation of
pure 10a .
3
1H NMR (499.99 MHz, C6D6, 293 K): δ 8.17 (d, J H1-H2
)
5.6 Hz, 1H, H1), 7.65 (d, 3J H25-H26 ) 7.6 Hz, 2H, H25), 7.34 (dd,
3J H26-H25 ) 3J H26-H27 ) 7.6 Hz, 2H, H26), 7.05 (m, 3H, H20 and
H
27), 6.96 (dd, 3J H21-H22 ) 8.8 Hz, 3J H21-H20 ) 7.6 Hz, 2H, H21),
3 4
6.71 (t, J H22-H21 ) 8.8 Hz, 1H, H22), 6.69 (d, J H11-H9 ) 1.7

Zirconium Complexes of Diamine Ligands
Organometallics, Vol. 21, No. 7, 2002 1373
4
Hz, 2H, H11), 6.40 (d, J H9-H11 ) 1.7 Hz, 2H, H9), 6.32 (ddd,
3
4
3J H3-H4 ) 7.6 Hz, J H3-H2 ) 7.8 Hz, J H3-H1 ) 1.7 Hz, 1H, H3),
3
3
6.06 (dd, J H2-H1 ) 5.6 Hz, J H2-H3 ) 7.8 Hz, 1H, H2), 5.57 (d,
3J H4-H3 ) 7.6 Hz, 1H, H4), 3.71 (d, J H7-H7′ ) 13.2 Hz, 2H,
2
2
H
7or7′), 3.02 (s, 2H, H23), 2.89 (s, 2H, H6), 2.53 (d, J H7-H7′
)
13.2 Hz, 2H, H7or7′), 2.49 (s, 2H, H18), 2.27 (s, 6H, H14), 2.11 (s,
6H, H15). 13C{1H} NMR (125.74 MHz, C6D6, 293 K): δ 158.3
(C13), 158.2 (C5), 149.3 (C19), 148.2 (C1), 146.4 (C24), 137.2 (C3),
131.8 (C11), 129.3 (C26), 128.8 (C25), 128.5 (C21), 128.1 (C9), 127.8
(C20), 127.0 (C10), 125.5 (C12), 123.7 (C8), 122.6 (C27), 121.9 (C2),
120.8 (C4), 120.6 (C22), 65.6 (C18), 65.3 (C23), 63.1 (C7), 59.7 (C6),
20.6 (C15), 16.6 (C14). IR (Nujol mull): ν (cm-1) 1604 (m), 1592
(s), 1568 (w), 1250 (m), 1208 (m), 1176 (w), 1122 (vw), 1088
(w), 1058 (w), 1014 (w), 1004 (w), 958 (s), 854 (s), 820 (s), 794
(m), 761 (m), 746 (s), 703 (m), 696 (s), 640 (w), 622 (vw), 590
(m), 556 (m), 542 (m), 516 (m). MS-EI (m/z): 555 (20%) [M -
C7H7]+, 464 (5%) [M - 2C7H7]+. Anal. Found (Calcd for
C
38H40N2O2Zr): C, 69.91 (70.44), H 6.19 (6.22), N 4.31 (4.32).
Zr (CH2C6H5)2(O2NN′tBu ) (10b). Meth od A. 10b was formed
by a procedure analogous with that for Zr(CH2C6H5)2(O2NN′Me),
with H2O2NN′tBu (0.3 g, 0.55 mmol) and Zr(CH2C6H5)4 (0.25 g,
0.545 mmol) in benzene (30 mL). After evaporation of the
volatiles, the crude product was extracted into ether (80 mL).
The resulting solution was filtered, concentrated to 60 mL, and
cooled to -30 °C to yield a yellow crystalline powder. Yield:
0.24 g (54%).
Meth od B (NMR tube scale). 10b was formed by a proce-
dure analogous with that for Zr(CH2C6H5)2(O2NN′Me), with
C6H5CH2MgCl (34 mL, 42.5 µmol) and ZrCl2(O2NN′tBu) (15.3
mg, 28.5 µmol) in C6D6 (1 mL). The complete conversion of
) 7.4 Hz, 1H, H2), 6.88 (apparent triplet, 3J H21-H22 ) 3J H21-H20
) 7.4 Hz, 2H, H21), 6.83 (s, 2H, H11), 6.82 (1H, H4), 6.79 (t,
3J H22-H21 ) 7.4 Hz, 1H, H22), 6.76 (s, 2H, H9), 6.74 (d, 3J H20-H21
2
) 7.4 Hz, 2H, H20), 3.98 (vbr s, 4H, H28), 3.96 (d, J H7-H7′
)
2
13.7 Hz, 2H, H7or7′), 3.83 (s, 2H, H6), 3.51 (d, J H7-H7′ ) 13.7
Hz, 2H, H7or7′), 3.27 (s, 2H, H23), 2.79 (br s, 2H, H18), 2.15 (s,
12H, H14 and H15), 1.95 (vbr s, 4H, H29). 13C{1H} NMR (125.74
MHz, CD2Cl2, 293 K): δ 159.7 (C5), 156.2 (C13), 150.1 (C1), 148.9
(C19), 148.4 (1J 13C-19F ) 226 Hz, o-C6F5), 140.8 (C3), 138.1
(1J 13C-19F ) 245 Hz, p-C6F5), 136.7 (1J 13C-19F ) 235 Hz, m-C6F5),
136.5 (C24), 133.2 (C25), 132.6 (C11), 131.8 (C26), 130.6 (C10 or
C12), 129.0 (C20), 128.1 (C27), 127.1 (C9 and C21), 125.3 (C10 or
the starting materials into 10b took 3 h.
3
1H NMR (499.99 MHz, C6D6, 293 K): δ 8.18 (d, J H1-H2
)
4.7 Hz, 1H, H1), 7.83 (d, 3J H25-H26 ) 7.6 Hz, 2H, H25), 7.40 (dd,
3J H26-H25 ) 7.6 Hz, 3J H26-H27 ) 7.4 Hz, 2H, H26), 7.35 (d, 4J H11-H9
3
) 2.4 Hz, 2H, H11), 7.08 (t, J H26-H27 ) 7.4 Hz, 1H, H27), 7.04
3
3
(d, J H20-H21 ) 7.6 Hz, 2H, H20), 6.89 (dd, J H21-H22 ) 7.4 Hz,
4
3J H21-H20 ) 7.6 Hz, 2H, H21), 6.80 (d, J H9-H11 ) 2.4 Hz, 2H,
C
12), 123.9 (C2), 122.7 (C8), 122.3 (C4 and C22), 75.7 (br, C28),
3
3
H9), 6.65 (t, J H22-H21 ) 7.4 Hz, 1H, H22), 6.32 (ddd, J H3-H4
)
70.0 (C23), 63.9 (C7), 59.7 (C6), 32.1 (C18), 25.9 (C29), 20.4 (C15),
3
4
16.3 (C14). 19F NMR (300 MHz, CD2Cl2, 293 K): δ -131.17 (d,
8.0 Hz, J H3-H2 ) 7.4 Hz, J H3-H1 ) 1.7 Hz, 1H, H3), 6.08 (dd,
3J H2-H1 ) 4.7 Hz, 3J H2-H3 ) 7.4 Hz, 1H, H2), 5.57 (d, 3J H4-H3
)
3
3J oF-mF ) 21.2 Hz, 6F, o-F), -164.32 (t, J pF-mF ) 20.4 Hz,
8.0 Hz, 1H, H4), 3.75 (d, 2J H7-H7′ ) 13.2 Hz, 2H, H7or7′), 3.21 (s,
2H, H23), 2.88 (s, 2H, H6), 2.59 (d, 2J H7-H7′ ) 13.2 Hz, 2H, H7or7′),
2.56 (s, 2H, H18), 1.67 (s, 18H, H15), 1.28 (s, 18H, H17). 13C-
{1H} NMR (125.74 MHz, C6D6, 293 K): δ 158.7 (C13), 158.6 (C5),
149.9 (C19), 149.3 (C1), 146.4 (C24), 140.6 (C10), 137.3 (C3), 136.3
(C12), 129.4 (C26), 128.6 (C25), 128.4 (C21), 127.5 (C20), 124.9 (C9),
124.85 (C8), 124.2 (C11), 122.9 (C27), 121.7 (C2), 120.9 (C4), 120.4
(C22), 67.6 (C23), 67.0 (C18), 63.7 (C7), 58.8 (C6), 35.4 (C14), 34.2
(C16), 31.9 (C17), 30.3 (C15). IR (Nujol mull): ν (cm-1) 1603 (w),
1593 (s), 1568 (w), 1416 (w), 1241 (m), 1213 (m), 1171 (m),
1132 (w), 1059 (vw), 1000 (m), 977 (s), 916 (m), 882 (m), 855
(w), 843 (s), 763 (w), 746 (vw), 697 (vs), 644 (w), 630 (w), 597
(vw), 572 (m), 547 (m), 518 (vw), 502 (vw). MS-EI (m/z): 723
(100%) [M - C7H7]+, 631 (15%) [M - 2C7H7]+. Anal. Found
(Calcd for C50H64N2O2Zr): C, 73.39 (73.57), H 7.88 (7.90), N
3.40 (3.43).
{[Zr (CH 2P h )(TH F )(O2NN′Me)][P h CH 2B(C6F 5)3]} (11a ).
Meth od A. A solution of B(C6F5)3 (0.036 g, 0.071 mmol) in
CH2Cl2 (2 mL) was added at room temperature to Zr(CH2Ph)2-
(O2NN′Me) (0.046 g, 0.071 mmol) in CH2Cl2 (4 mL) in the
presence of THF (6 µL, 0.073 mmol). After 90 min at room
temperature, the solvent was removed under reduced pressure
to yield a white-yellow powder. Yield: 0.08 g (95%).
3F, p-F), -167.15 (m, 6F, m-F). Anal. Found (Calcd for C60H48
-
BF15N2O3Zr‚0.2CH2Cl2): C, 57.49 (57.90), H 3.71 (3.90), N 2.18
(2.24).
{[Zr (CH2P h )(THF )(O2NN′tBu )][P h CH2B(C6F 5)3]} (11b).
Meth od A. 11b was formed by a procedure analogous with
that for {[Zr(CH2Ph)(O2NN′Me)][PhCH2B(C6F5)3]}, with Zr(CH2-
Ph)2(O2NN′tBu) (0.07 g, 0.086 mmol), B(C6F5)3 (0.044 g, 0.086
mmol), and THF (7 µL, 0.086 mmol) in CD2Cl2 (6 mL). Yield
) 0.10 g (85%).
Meth od B (NMR tube scale). At room temperature, a
solution of B(C6F5)3 (0.0063 g, 0.012 mmol) in CD2Cl2 (0.5 mL)
was added to Zr(CH2Ph)2(O2NN′tBu) (0.01 g, 0.012 mmol) in
CD2Cl2 (0.5 mL) in the presence of THF (1.0 µL, 0.012 mmol).
The product 11b formed quantitatively.
1H NMR (499.99 MHz, CD2Cl2, 293 K): δ 8.51 (d, 3J H1-H2
)
5.2 Hz, 1H, H1), 7.76 (d, 3J H25-H26 ) 7.2 Hz, 2H, H25), 7.59 (dd,
3
3J H26-H25 ) 7.2 Hz, J H26-H27 ) 7.5 Hz, 2H, H26), 7.56 (ddd,
4
3J H3-H4 ) 3J H3-H2 ) 7.7 Hz, J H3-H1 ) 1.5 Hz, 1H, H3), 7.32 (t,
4
3J H26-H27 ) 7.5 Hz, 1H, H27), 7.24 (d, J H11-H9 ) 2.5 Hz, 2H,
3
3
H
11), 7.16 (dd, J H2-H1 ) 5.2 Hz, J H2-H3 ) 7.7 Hz, 1H, H2),
4 3
7.06 (d, J H9-H11 ) 2.5 Hz, 2H, H9), 6.87 (dd, J H21-H22 ) 7.8
3
3
Hz, J H21-H20 ) 6.9 Hz, 2H, H21), 6.78 (d, J H4-H3 ) 7.7 Hz,
1H, H4), 6.775 (t, 3J H22-H21 ) 7.8 Hz, 1H, H22), 6.75 (d, 3J H20-H21
) 6.9 Hz, 2H, H20), 3.97 (d, 2J H7-H7′ ) 13.5 Hz, 2H, H7or7′), 3.91
Meth od B (NMR tube scale). At room temperature, a
solution of B(C6F5)3 (0.0078 g, 0.015 mmol) in CD2Cl2 (0.5 mL)
was added to Zr(CH2Ph)2(O2NN′Me) (0.01 g, 0.015 mmol) in
CD2Cl2 (0.5 mL) in the presence of THF (1.3 µL, 0.016 mmol).
2
(s, 2H, H6), 3.80 (vbr s, 4H, H28), 3.61 (d, J H7-H7′ ) 13.5 Hz,
2H, H7or7′), 3.29 (s, 2H, H23), 2.81 (br s, 2H, H18), 1.87 (vbr s,
4H, H29), 1.44 (s, 18H, H15), 1.23 (s, 18H, H17). 13C{1H} NMR
(125.74 MHz, CD2Cl2, 293 K): δ 159.6 (C5), 156.3 (C13), 150.6
(C1), 148.6 (C19), 148.4 (1J 13C-19F ) 226 Hz, o-C6F5), 143.8 (C10),
140.6 (C3), 138.1 (1J 13C-19F ) 245 Hz, p-C6F5), 136.7 (1J 13C-19F
) 235 Hz, m-C6F5), 136.5 (C24), 135.9 (C12), 132.3 (C25), 131.2
The compound 11a was formed quantitatively.
3
1H NMR (499.99 MHz, CD2Cl2, 293 K): δ 8.61 (d, J H1-H2
)
5.6 Hz, 1H, H1), 7.62-7.55 (m, 5H, H3, H25, and H26), 7.33 (t,
3J H26-H27 ) 7.2 Hz, 1H, H27), 7.15 (dd, 3J H2-H1 ) 5.6 Hz, 3J H2-H3

1374 Organometallics, Vol. 21, No. 7, 2002
Toupance et al.
Ta ble 1. X-r a y Da ta Collection a n d P r ocessin g P a r a m eter s for Zr Cl2(O2NN′Me) (3a ),
Zr Cl2(O2NN′tBu )‚0.35C6H14 (3b‚0.35C6H14), Zr (O2NN′Me)2‚2C6H6 (4a ‚2C6H6), Zr (NMe2)2(O2NN′tBu ) (5b),
Zr Me2(O2NN′Me) (6a ), Zr Me2(O2NN′tBu ) (6b), a n d Zr (CH2P h )2(O2NN′Me) (10a )
3a
3b‚0.35C6H14
4a ‚2C6H6
molecular formula
fw
cryst syst
space group
C24H26Cl2N2O2Zr
536.61
triclinic
P1h
2
C36H50Cl2N2O2Zr‚0.35 C6H14
C48H52N4O4Zr‚2 C6H6
735.10
monoclinic
C2/c
996.41
tetragonal
P42/n
Z
8
8
a/Å
b/Å
c/Å
8.7656(3)
12.3126(4)
15.8989(6)
71.051(2)
76.120(2)
79.316(2)
1564.7(1)
1.14
293
0.54
10 196
7061
4167
281
R1 ) 0.0539
Rw ) 0.0579
0.95 and -0.62
36.3440(5)
13.7738(2)
18.1546(3)
90
117.4049(7)
90
8068.2(2)
1.21
150
0.44
17 293
9210
6783
401
24.919(1)
24.919(1)
18.1356(8)
90
90
90
11261.6(8)
1.18
150
R/deg
â/deg
γ/deg
volume/Å3
density(calcd)/mg m-3
temperature/K
µ (Mo KR, λ ) 0.71073 Å)/mm-1
no. of reflns collected
no. of ind reflns
obsd reflns [I > 3σ(I)]
no. of params refined
final R indicesa [I>3σ(I)]
0.24
20 380
12 440
5028
623
R1 ) 0.0426
Rw ) 0.0490
0.92 and -0.80
R1 ) 0.0802
Rw ) 0.0771
0.95 and -0.71
largest residual peaks/e Å-3
5b
6a
6b
molecular formula
fw
cryst syst
space group
C40H62NO2Zr
722.18
triclinic
P1h
2
C26H32N2O2Zr
495.77
tetragonal
P421c
C38H56N2O2Zr
664.10
monoclinic
C2/c
Z
8
8
a/Å
b/Å
c/Å
10.1513(1)
10.2107(1)
19.7534(3)
104.8043(5)
97.6019(5)
95.2271(7)
1945.37(4)
1.23
150
0.32
16 332
8867
7362
425
R1 ) 0.0329
Rw ) 0.0382
0.72 and -0.79
18.8350(7)
18.8350(7)
13.8284(3)
90
90
90
4905.7(3)
1.34
150
0.47
10 209
9992
6016
281
R1 ) 0.0415
Rw ) 0.0457
0.69 and -0.57
31.5313(4)
14.2743(2)
16.9292(2)
90
108.1635(6)
90
7239.9(2)
1.22
150
0.34
15 932
8195
5502
R/deg
â/deg
γ/deg
volume/Å3
density(calcd)/Mg m-3
temperature/K
µ (Mo KR, λ ) 0.71073 Å)/mm-1
no. of reflns collected
no. of ind reflns
no. of obsd reflns [I > 3σ(I)]
no. of params refined
final R indicesa [I>3σ(I)]
388
R1 ) 0.0352
Rw ) 0.0390
0.66 and -0.63
largest residual peaks/e Å-3
10a
molecular formula
C38H40N2O2Zr
fw
647.97
monoclinic
P21/n
cryst syst
space group
Z
4
a/Å
b/Å
c/Å
11.1165(2)
21.9660(5)
13.7130(2)
90
103.512(1)
90
3255.8(1)
1.32
150
R/deg
â/deg
γ/deg
volume/Å3
density(calcd)/Mg m-3
temperature/K
µ (Mo KR, λ ) 0.71073 Å)/mm-1
no. of reflns collected
0.37
12 142
7436
no. of ind reflns
no. of obsd reflns [I > 3σ(I)]
4957
415
R1 ) 0.0348
Rw ) 0.0374
0.43 and -0.47
no. of params refined
final R indicesa [I > 3σ(I)]
largest residual peaks/e Å-3
a
2
R1 ) ∑||Fo| - |Fc||/∑|Fo|; Rw ) {∑w(|Fo| - |Fc|)2/∑(w|Fo| }1/2
.

Zirconium Complexes of Diamine Ligands
Organometallics, Vol. 21, No. 7, 2002 1375
Sch em e 1. Syn th esis of Sod iu m Sa lts of th e Dia m in e-Bis(p h en ola te) Liga n d s, a n d Zir con iu m
Mon o(d ia m in e-bis(p h en ola te)) Dich lor id e a n d Bis(d ia m in e-bis(p h en ola te)) Com p lexes
(C26), 128.7 (C20), 127.6 (C27), 126.7 (C21), 125.7 (C9), 125.3 (C11),
123.6 (C2), 123.4 (C8), 122.3 and 122.0 (C4 and C22), 76.2 (C28),
71.6 (C23), 64.5 (C7), 58.7 (C6), 35.3 (C14), 34.6 (C16), 31.9 (C18),
31.6 (C17), 30.1 (C15), 26.0 (C29). 19F NMR (300 MHz, CD2Cl2,
groups of H atoms. There are no unusual features concerning
the benzylic CH2 group H atoms.
Crystallographic calculations were performed using SIR9238
and CRYSTALS.41 A full listing of atomic coordinates, bond
lengths and angles, and displacement parameters for 3a , 3b,
4a , 5b, 6a , 6b, and 10a has been deposited at the Cambridge
Crystallographic Data Center. See Notice to Authors, Issue
No. 1.
3
293 K): δ -131.18 (d, J oF-mF ) 21.2 Hz, 6F, o-F), -164.44 (t,
3J pF-mF ) 20.4 Hz, 3F, p-F), -167.20 (m, 6F, m-F). IR (Nujol
mull): ν (cm-1) 1639 (m), 1610 (w), 1600 (vw), 1510 (s), 1305
(w), 1240 (w), 1204 (w), 1168 (m), 1128 (w), 1079 (s), 1026 (w),
973 (m), 838 (m), 808 (m), 754 (m), 724 (m), 701 (m), 679 (w),
650 (w), 633 (vw), 597 (w), 569 (m), 552 (m). Anal. Found
(Calcd for C72H72BF15N2O3Zr‚0.15CH2Cl2): C, 61.02 (61.32), H
5.41 (5.15), N 1.85 (1.98).
Resu lts a n d Discu ssion
Liga n d P r ecu r sor s a n d th eir Disod iu m Sa lts. An
independent synthesis of the tert-butyl-substituted ligand
precursor H2O2NN′tBu (1b, Chart 1) has been described
very recently.28 In our hands the multigram scale
Cr ysta l Str u ctu r e Deter m in a tion s for Zr Cl2(O2NN′Me
)
(3a ), Zr Cl2(O2NN′t Bu )‚0.35C6H 14 (3b ‚0.35C6H 14), Zr (O2-
NN′Me)2‚2C6H6 (4a‚2C6H6), Zr (NMe2)2(O2NN′tBu) (5b), Zr Me2-
(O2NN′Me) (6a ), Zr Me2(O2NN′tBu ) (6b), a n d Zr (CH2P h )2-
(O2NN′Me) (10a ). Crystal data collection and processing
parameters are given in Table 1. Crystals were immersed in
a film of perfluoropolyether oil on a glass fiber and transferred
to an Enraf-Nonius Kappa CCD diffractometer equipped with
an Oxford Cryosystems low-temperature device.36 Data were
collected at low temperature using Mo KR radiation; equiva-
lent reflections were merged, and the images were processed
with the DENZO and SCALEPACK programs.37 Corrections
for Lorentz-polarization effects and absorption were per-
formed, and the structures were solved by direct methods using
SIR92.38 Subsequent difference Fourier syntheses revealed the
positions of all other non-hydrogen atoms. Hydrogen atoms
were either placed geometrically and refined in a riding model
or (for 10a ) located from Fourier maps and refined as indicated
below. Extinction corrections were applied as required,39 and
examination of the refined Flack parameter40 for 4a and 6a
confirmed the correct polarity.
t
syntheses of H2O2NN′R [R ) Me (1a ) or Bu (1b)] were
readily achieved by a Mannich condensation between
paraformaldehyde, (2-C5H4N)CH2NH2, and the appro-
priate 2,4-disubstituted phenol HO-2,4-C6H2R2 (R ) Me
or tBu) in a 1:1:2 molar ratio in ethanol in a sealed
ampule at 110 °C for 3 days. Typical yields of 50-55%
are readily achieved in this way, affording 1a and 1b
as white microcrystalline solids. If the reaction is carried
out under open reflux conditions (water-cooled con-
denser), then incomplete conversions of (2-C5H4N)CH2-
NH2 and 2,4-disubstituted phenol are observed, consis-
tent with the partial loss of paraformaldehyde from the
reaction mixture.
The protio-ligands H2O2NN′R were smoothly con-
verted to their disodium derivatives Na2O2NN′R [R )
t
Me (2a ) or Bu (2b)] by reaction with an excess of sodium
For 3b‚0.35C6H14 residual electron density was modeled as
a 70% chemical occupancy hexane molecule of crystallization
(lying across a crystallographic 2-fold rotation axis). The
disordered atoms were refined isotropically. For 4a ‚2C6H6 the
benzene molecules of crystallization were refined anisotropi-
cally subject to similarity restraints on the C-C distances and
general vibrational restraints. For 10b all H atoms were
located from Fourier diffrence syntheses. The H atoms of the
benzylic CH2 groups were positionally and isotropically refined.
All others were refined in a riding model with equivalent
isotropic displacement parameters for chemically related
hydride in THF (Scheme 1). Filtering and evaporation
(36) Cosier, J .; Glazer, A. M. J . Appl. Crystallogr. 1986, 19, 105.
(37) Gewirth, D. The HKL Manual, written with the cooperation of
the program authors, Otwinowski, Z., Minor, W.; Yale University, 1995.
(38) Altomare, A.; Cascarano, G.; Giacovazzo, G.; Guagliardi, A.;
Burla, M. C.; Polidori, G.; Camalli, M. J . Appl. Crystallogr. 1994, 27,
435.
(39) Larson, A. C. Acta Crystallogr. 1967, 12, 664.
(40) Flack, H. Acta Crystallogr., Sect. A 1983, 39, 876.
(41) Watkin, D. J .; Prout, C. K.; Carruthers, J . R.; Betteridge, P.
W. CRYSTALS Issue 10; Chemical Crystallography Laboratory;
University of Oxford, 1996.

1376 Organometallics, Vol. 21, No. 7, 2002
Toupance et al.
of the solvents yielded 2a or 2b as mildly air-sensitive
white solids soluble and stable in aromatic and nonha-
logenated donor solvents. Despite prolonged drying at
90 °C under vacuum, the dimethyl derivative 2a con-
tained small, nonstoichiometric quantities of THF (de-
termined by 1H NMR integration). Both compounds are
formulated for convenience as Na2O2NN′R, but since we
were unable to obtain diffraction-quality crystals, we
cannot comment on their actual nuclearity. NMR stud-
ies have proved inconclusive in these regards. Both the
protio (1a , 1b) and disodium (2a , 2b) derivatives are
useful precursors to new zirconium complexes.
The 1H NMR spectra of 3a and 3b readily distinguish
between the C1 and Cs symmetry isomers. For example,
the former has two chemically distinct phenoxide ring
environments (one trans to chloride, the other trans to
the pyridyl group), whereas in the latter isomer the
mutually trans phenoxide groups give rise to a single
set of resonances. It is not surprising that the tert-butyl-
substituted complex 3b has proportionally less of the
C1 symmetry isomer since this places the phenoxide
ligands mutually cis to each other, an arrangement that
should become less favorable as the steric bulk of the
phenoxide ring substituents is increased. The nature of
the fluxional processes responsible for the broad NMR
spectra of 3a and 3b at room temperature is as yet
Zir con iu m Dich lor id e Com p lexes of Dia m in e-
Bis(p h en ola te) Liga n d s. The reactions between H2O2-
NN′R (1a , 1b) or Na2O2NN′R (2a , 2b) and a number of
zirconium precursor complexes are summarized in
Scheme 1. The course and outcome of the reaction
chemistry is dependent on the identity of the phenoxide
ring substituents, presumably because of the different
steric factors involved.
Protonolysis reactions of either 1a or 1b with Zr(CH2-
31
SiMe3)2Cl2(Et2O)2 in benzene lead to elimination of
SiMe4 and formation of the dichloride complexes ZrCl2(O2-
t
NN′R) (R ) Me (3a ) or Bu (3b)) in 69 and 63% isolated
n
unknown. Addition of either 1 or 10 equiv of Bu4Cl (a
yield, respectively. Both of these compounds have been
crystallographically characterized, and the structures
are discussed below. Reaction of the disodium salts
Na2O2NN′R (2a , 2b) with ZrCl4 or ZrCl4(THF)2 with the
aim of forming 3a and 3b was successful only for the
tert-butyl-substituted system 3b, this being obtained in
50% yield. For the methyl-substituted ligand these
reactions gave mixtures of ZrCl2(O2NN′Me) (3a ) and the
eight coordinate bis(diamine-bis(phenolate)) complex
Zr(O2NN′Me)2 (4a ). The latter has been isolated in 42%
yield by treating ZrCl4(THF)2 with 2 equiv of Na2O2-
NN′Me. Compound 4a can also be obtained in a similar
yield by an SiMe4 elimination reaction between Zr(CH2-
SiMe3)4 and 2 equiv of H2O2NN′Me. All attempts to make
the tert-butyl-substituted analogue of 4a were unsuc-
cessful, reflecting the greater steric demands of the O2-
NN′tBu ligand. Compound 4a has been structurally
characterized, and the solid-state structure is discussed
below.
chloride ion source) does not influence the spectral line
widths or equilibrium position between C1 and Cs
symmetry isomers, militating against a mechanism
involving dissociation of chloride ions. However, it is in
principle possible that pyridyl group dissociation can
occur on the NMR time scale and that this would give
a five-coordinate intermediate through which one phe-
noxide and the pyridyl donor could exchange positions
(i.e., to be cis or trans to the other phenoxide group).
To probe further the mechanism of interconversion
between the C1 and Cs symmetry isomers of 3b, we
carried out a variable-temperature, 1H NMR line shape
analysis in dichloromethane-d2 solution, using all four
pairs of exchanging resonances of the two different
pyridyl groups. Selected examples of the observed and
simulated42 spectra in this region are illustrated in
Figure 1. Analysis of a set of 10 first-order rate
constants (between -30 and 20 °C) for 3b using
standard (Eyring plot) procedures43 afforded the follow-
ing activation parameters: ∆Hq ) 35.9(8) kJ mol-1; ∆Sq
) -102(5) J mol-1 K-1; ∆Gq(298K) ) 66(2) kJ mol-1. The
somewhat negative entropy of activation disfavors a
dissociatively activated mechanism (e.g., by chloride or
pyridyl donor loss), as does the relatively modest en-
thalpy of activation.44 Rather, the activation parameters
are more in favor of a nondissociative rearrangement
(for example, via a trigonal prismatic transition state
or intermediate45), possibly with a somewhat ordered
transition state (although the effects of differing extents
of solvation cannot be disregarded). Furthermore, we
found that the NMR line widths are independent of
sample concentration in the concentration range 0.014
to 0.045 mmol of 3b, consistent with an intramolecular
exchange mechanism.
At room temperature the H and 13C NMR spectra of
1
t
ZrCl2(O2NN′R) (R ) Me (3a ) or Bu (3b)) in CD2Cl2 are
broad and relatively uninformative. However, cooling
to -60 °C leads to a considerable sharpening of the
resonances. These NMR spectra are consistent with the
presence of two isomers, one having C1 symmetry and
the other having Cs symmetry. For the two compounds
3a and 3b these are present in the ratios ca. 95:5 and
65:35, respectively, by 1H NMR integration. The relative
amounts of each isomer do not depend on the actual
method of preparation; nor do they change with tem-
perature, suggesting that there is a negligible entropic
contribution to the Gibbs free energies involved. The two
isomers are illustrated in eq 1, which also shows the
proposed dynamic equilibrium between them. That the
two isomers are in dynamic exhange is apparent from
the variable-temperature NMR spectra. For example,
at low temperature the 1H NMR spectra show two
pyridyl group ortho (to N) H atom resonances for 3a and
3b; on warming, these coalesce to a weighted average
chemical shift.
(42) Budzelaar, P. H. M. gNMR for Windows v4.1; Cherwell Scien-
tific Ltd.: Oxford, 1999.
(43) Sandstro¨m, J . Dynamic NMR Spectroscopy; Academic Press:
London, 1992.
(44) Wilkins, R. G. Kinetics and Mechanism of Reactions of Transi-
tion Metal Complexes; VCH: Weinheim, 1991.
(45) Muetterties, E. L. J . Am. Chem. Soc. 1968, 90, 5097.

Zirconium Complexes of Diamine Ligands
Organometallics, Vol. 21, No. 7, 2002 1377
F igu r e 3. Displacement ellipsoid plot (25% probablility)
of ZrCl2(O2NN′tBu) (3b) with hydrogen atoms and hexane
molecule of crystallization omitted.
F igu r e 1. Selected simulated (left) and observed variable-
temperature 1H NMR spectra of the aromatic region of
ZrCl2(O2NN′Me) (3a ) in dichloromethane-d2. The observed
resonances (marked with a “*”) for the C6H2But ring
2
protons were not included in the simulation and are
therefore “missing” from the simulated spectra.
F igu r e 2. Displacement ellipsoid plot (15% probablility)
of ZrCl2(O2NN′Me) (3a ) with hydrogen atoms omitted.
The NMR spectra of the homoleptic complex Zr(O2-
NN′Me)2 (4a ) are sharp at room temperature and feature
one set of O2NN′Me ligand resonances with the two
phenoxide groups in chemically inequivalent environ-
ments. This suggests that these phenoxide groups adopt
a mutually cis disposition (as in the C1 symmetric
isomers of 3a and 3b) and that the two O2NN′Me ligands
are related by a molecular symmetry element (or
undergo rapid exchange on the NMR time scale).
F igu r e 4. Displacement ellipsoid plot (20% probablility)
of Zr(O2NN′Me
) (4a ) with hydrogen atoms and benzene
2
molecules of crystallization omitted.
revealed NOE interactions between these pyridyl ortho
hydrogens and the ortho methyl hydrogens of a phe-
noxide group (most probably those attached to C(15) or
C(31) in Figure 4).
The solid-state structures of ZrCl2(O2NN′Me) (3a as
the C1 symmetric isomer), ZrCl2(O2NN′tBu) (3b as the
Cs symmetric isomer) and Zr(O2NN′Me)2 (4a ) have all
been determined and are shown in Figures 2-4. Se-
lected bond lengths and angles are listed in Tables 2-4.
Crystals of 3b and 4a contain hexane or benzene
molecules of crystallization, but there are no unusual
contacts between these and the metal complexes.
1
Cooling a H NMR sample of 4a to -60 °C resulted in
no significant change to the spectrum. In all of the
complexes 3a , 3b (both isomers), and 4a the 1H chemical
shifts of the ortho hydrogen of the pyridyl moiety are
consistent with coordination of this group to the metal
center in solution. This was also confirmed by the two-
dimensional NOESY (nuclear Overhauser effect cor-
relation spectroscopy) spectra of 3a and 4a , which

1378 Organometallics, Vol. 21, No. 7, 2002
Toupance et al.
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles
Zr(1)-Cl(2) (chloride trans to phenoxide) distance of
2.483(1) Å in 3a is significantly longer that the other
Zr-Cl distance in 3a [2.422(1) Å, trans to the amine
donor N(1)] and the two Zr-Cl distances of 2.4205(6)
and 2.4309(6) Å in 3b (both Zr-Cl bonds being trans to
neutral N-donor atoms). Similarly the Zr(1)-O(2) (trans
to neutral pyridyl) distance of 1.935(3) Å in 3a is
significantly shorter than the three other Zr-O dis-
tances in 3a and 3b (range 1.966(2)-1.997(2) Å) for
phenoxide groups trans to anionic donors.
(d eg) for Zr Cl2(O2NN′Me) (3a )
Distances
Zr(1)-Cl(1)
Zr(1)-Cl(2)
Zr(1)-O(1)
2.422(1)
2.483(1)
1.983(3)
Zr(1)-O(2)
Zr(1)-N(1)
Zr(1)-N(2)
1.935(3)
2.409(3)
2.332(3)
Angles
Cl(1)-Zr(1)-Cl(2)
Cl(1)-Zr(1)-O(1)
94.37(4)
94.83(8)
O(1)-Zr(1)-N(1)
80.80(11)
80.69(11)
O(2)-Zr(1)-N(1)
Cl(2)-Zr(1)-O(1) 159.41(8)
Cl(1)-Zr(1)-O(2) 107.40(8)
Cl(1)-Zr(1)-N(2) 100.08(8)
Cl(2)-Zr(1)-N(2)
O(1)-Zr(1)-N(2)
80.45(8)
79.84(11)
The solid-state structure of Zr(O2NN′Me
)
2
(4a ) is
Cl(2)-Zr(1)-O(2)
O(1)-Zr(1)-O(2)
95.09(9)
99.65(12) O(2)-Zr(1)-N(2) 152.44(11)
consistent with the solution NMR data discussed above
and features two tetradentate O2NN′Me ligands, each
with mutually cis phenoxide donors. In the solid state
4a possesses approximate C2 symmetry; Figure 4 shows
a view of 4a approximately along the molecular 2-fold
axis that relates the two O2NN′Me ligands. The geometry
at zirconium is best described as a square anti-prism,
with atoms O(1), N(2), O(3), and N(3) forming one of
the (approximately) square faces and atoms O(2), N(1),
O(4), and N(4) forming the other. The Zr-O and Zr-
Namine and Zr-Npyridyl distances in 4a are all signifi-
cantly longer than the corresponding distances in six-
coordinate 3a and 3b. This reflects the increased
coordination number and steric crowding in 4a . For all
three compounds 3a , 3b, and 4a the intramolecular
distances and angles are within previously reported
ranges.46
The tendency of the zirconium dichloride complexes
of O2NN′R (i.e., 3a , 3b, and 4a ) to exist as isomeric
mixtures and also to form the bis(O2NN′Me) derivative
4a is reminiscent of previously reported group 4 com-
plexes of chelating (bi- or tetradentate) O,N-donor
ligands11-21 and appears to be an intrinsic feature of
these systems.
Cl(1)-Zr(1)-N(1) 171.44(9)
N(1)-Zr(1)-N(2)
72.0(1)
Cl(2)-Zr(1)-N(1)
87.54(8)
Ta ble 3. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for Zr Cl2(O2NN′tBu ) (3b)
Distances
Zr(1)-Cl(1)
Zr(1)-Cl(2)
Zr(1)-O(1)
2.4205(6)
2.4309(6)
1.966(2)
Zr(1)-O(2)
Zr(1)-N(1)
Zr(1)-N(2)
1.997(2)
2.397(2)
2.377(2)
Angles
Cl(1)-Zr(1)-Cl(2) 102.06(3) N(1)-Zr(1)-O(1)
78.63(6)
86.69(7)
94.81(5)
98.88(5)
80.65(6)
80.50(7)
158.16(7)
Cl(1)-Zr(1)-N(1)
Cl(2)-Zr(1)-N(1)
Cl(1)-Zr(1)-N(2)
Cl(2)-Zr(1)-N(2)
N(1)-Zr(1)-N(2)
Cl(1)-Zr(1)-O(1)
Cl(2)-Zr(1)-O(1)
95.33(5) N(2)-Zr(1)-O(1)
162.57(5) Cl(1)-Zr(1)-O(2)
167.26(5) Cl(2)-Zr(1)-O(2)
90.41(5) N(1)-Zr(1)-O(2)
72.28(7) N(2)-Zr(1)-O(2)
93.89(5) O(1)-Zr(1)-O(2)
98.83(5)
Ta ble 4. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for Zr (O2NN′Me)2 (4a )
Distances
Zr(1)-O(1)
Zr(1)-O(2)
Zr(1)-O(3)
Zr(1)-O(4)
2.074(6)
2.054(5)
2.101(5)
2.058(6)
Zr(1)-N(1)
Zr(1)-N(2)
Zr(1)-N(3)
Zr(1)-N(4)
2.524(7)
2.462(7)
2.451(7)
2.547(7)
Angles
Zir con iu m Bis(d im eth yla m id e) a n d Or ga n om e-
t a llic Com p lexes w it h Dia m in e-Bis(p h en ola t e)
Liga n d s. Scheme 2 summarizes other new zirconium
complexes prepared in this work. Two synthetic strate-
gies have been evaluated. These are (i) protonolysis
reactions of H2O2NN′R (1a , 1b) with ZrR′4 (R′ ) NMe2,
CH2SiMe3, CH2CMe3, or CH2Ph), and (ii) chloride
substitution reactions of ZrCl2(2O2NN′R) (3a , 3b) with
organolithium or Grignard reagents.
Reaction of Zr(NMe2)4 with H2O2NN′Me (1a ) in cold
benzene gave elimination of HNMe2 (observed by 1H
NMR), but no well-defined zirconium complex could be
isolated. The problem appears to be one of thermal
stablilty since 1H NMR analysis of crude mixtures
immediately after reaction showed resonances attribut-
able to the desired product Zr(NMe2)2(2O2NN′Me). How-
ever, on further handling at room temperature and/or
attempted purification, the spectra became increasingly
ill-defined. In contrast, reaction of Zr(NMe2)4 with the
more sterically encumbered H2O2NN′tBu (1b) in benzene
gave Zr(NMe2)2(O2NN′tBu) (5b) as a white crystalline
material in 80% yield. Diffraction-quality crystals were
obtained by slow evaporation of a benzene solution. The
molecular structure is shown in Figure 5, and selected
bond lengths and angles are listed in Table 5.
O(1)-Zr(1)-O(2)
O(1)-Zr(1)-O(3)
O(2)-Zr(1)-O(3)
O(1)-Zr(1)-O(4)
O(2)-Zr(1)-O(4)
O(3)-Zr(1)-O(4)
O(1)-Zr(1)-N(1)
O(2)-Zr(1)-N(1)
O(3)-Zr(1)-N(1)
O(4)-Zr(1)-N(1)
O(1)-Zr(1)-N(2)
O(2)-Zr(1)-N(2)
O(3)-Zr(1)-N(2)
O(4)-Zr(1)-N(2)
94.5(2)
95.6(2)
141.6(2)
140.8(2)
101.1(2)
94.0(2)
77.5(2)
72.7(2)
145.7(2)
73.4(2)
72.9(2)
141.3(2)
77.0(2)
72.5(2)
O(1)-Zr(1)-N(3)
O(2)-Zr(1)-N(3)
O(3)-Zr(1)-N(3)
O(4)-Zr(1)-N(3)
N(1)-Zr(1)-N(3)
O(1)-Zr(1)-N(4)
O(2)-Zr(1)-N(4)
O(3)-Zr(1)-N(4)
O(4)-Zr(1)-N(4)
N(1)-Zr(1)-N(4)
N(2)-Zr(1)-N(3)
N(2)-Zr(1)-N(4)
N(3)-Zr(1)-N(4)
N(1)-Zr(1)-N(2)
77.8(2)
73.5(2)
72.6(2)
141.2(2)
135.8(2)
146.5(2)
74.4(2)
76.8(2)
72.7(2)
126.2(2)
134.9(2)
134.3(2)
68.8(2)
68.9(2)
The structures found for ZrCl2(O2NN′Me) (3a ) and
ZrCl2(O2NN′tBu) (3b) in the solid state are fully consis-
tent with the solution NMR data for the C1 symmetric
isomer of 3a and Cs symmetric isomer of 3b. By
inference, the assignment of the remaining peaks in the
NMR spectra of 3a and 3b to the other isomer (i.e., Cs
symmetric or C1 symmetric, respectively) is therefore
supported in each case. The zirconium centers in 3a and
3b are approximately octahedral and show that the
pyridyl moiety is tightly bound in each case. The two
chloride ligands and nitrogen donors in each compound
adopt mutually cis dispositions. But whereas the phe-
noxide ligands are also mutually cis in the C1 symmetric
isomer of 3a , they are mutually trans in the Cs sym-
metric 3b. This has some significant effects on the
zirconium-donor atom bond lengths due the different
trans influences of the various donors. For example, the
(46) Fletcher, D. A.; McMeeking, R. F.; Parkin, D. The United
Kingdom Chemical Database Service. J . Chem. Inf. Comput. Sci. 1996,
36, 746. Allen, F. H.; Kennard, O. Chem. Des. Autom. News 1993, 8,
1&31.

Zirconium Complexes of Diamine Ligands
Organometallics, Vol. 21, No. 7, 2002 1379
Sch em e 2. Syn th esis of Bis(d im eth yla m id e) a n d Or ga n om eta llic Zir con iu m Com p lexes of
Dia m in e-Bis(p h en ola te) Liga n d s
Molecules of 5b contain approximately octahedral
zirconium centers with mutually cis NMe2 ligands and
trans phenoxide groups. The Namine and Npyridyl donors
are therefore also mutually cis, and the compound
possess approximate Cs symmetry in the solid state. A
comparison of the Zr-O and Zr-Namine/pyridyl distances
in 5b with those of ZrCl2(O2NN′tBu) (3b, Table 3) shows
that those for 5b are all significantly longer. This is
consistent with the superior σ- and π-donor ability of
NMe2 in comparison with Cl as a ligand to transition
metal centers. The Zr-Namide distances are within
previously reported ranges for six-coordinate zirconium.
The sum of the angles subtended at the NMe2 nitrogens
[359.3(4)° for N(3) and 359.7(5)° for N(4)] show that they
are sp2 hybridized and potentially capable of π-donating
to the d0 metal center. The carbon atoms of the NMe2
ligand bound trans to the pyridyl group are effectively
coplanar with the “equatorial” (as drawn) {O(1), O(2),
N(2), N(3)} plane. To maximize π-donation from the
other NMe2 ligand (i.e., to avoid competition with the
NMe2 trans to pyridyl for metal “t2g” π-acceptor orbitals),
it would be expected that its methyl groups would lie
in the {N(1), N(2), N(3), N(4)} plane. This would give
an orthogonal (nonmutually competing) arrangement of
the NMe2 nitrogen lone pair 2pπ orbitals. In 5b, how-
ever, the methyl carbons of the axial NMe2 effectively
bisect the N(2)-Zr(1)-O(2) and O(1)-Zr(1)-N(3) angles
so that some competition between the two NMe2 nitro-
gen lone pairs presumably arises. The orientation of the
Ta ble 5. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for Zr (NMe2)2(O2NN′tBu ) (5b)
Distances
Zr(1)-O(1)
Zr(1)-O(2)
Zr(1)-N(1)
2.0380(11)
2.0245(11)
2.4670(13)
Zr(1)-N(2)
Zr(1)-N(3)
Zr(1)-N(4)
2.4597(14)
2.0706(14)
2.0832(14)
Angles
O(1)-Zr(1)-O(2) 156.70(5) O(2)-Zr(1)-N(4)
99.70(5)
159.69(6)
91.20(5)
103.23(6)
126.65(12)
122.50(12)
O(1)-Zr(1)-N(1)
O(2)-Zr(1)-N(1)
O(1)-Zr(1)-N(2)
O(2)-Zr(1)-N(2)
N(1)-Zr(1)-N(2)
O(1)-Zr(1)-N(3)
O(2)-Zr(1)-N(3)
N(1)-Zr(1)-N(3)
81.14(4) N(1)-Zr(1)-N(4)
76.06(4) N(2)-Zr(1)-N(4)
79.51(4) N(3)-Zr(1)-N(4)
87.82(5) Zr(1)-N(3)-C(37)
68.95(4) Zr(1)-N(3)-C(38)
90.89(5) C(37)-N(3)-C(38) 110.1(2)
96.53(5) Zr(1)-N(4)-C(39)
97.01(5) Zr(1)-N(4)-C(40)
120.86(14)
128.09(13)
F igu r e 5. Displacement ellipsoid plot (20% probablility)
of Zr(NMe2)2(O2NN′tBu) (5b) with hydrogen atoms omitted.
N(2)-Zr(1)-N(3) 163.93(5) C(39)-N(4)-C(40) 110.8(2)
O(1)-Zr(1)-N(4) 100.03(5)

1380 Organometallics, Vol. 21, No. 7, 2002
Toupance et al.
F igu r e 7. Displacement ellipsoid plot (25% probablility)
of ZrMe2(O2NN′tBu) (6b) with hydrogen atoms omitted.
Ta ble 6. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for Zr Me2(O2NN′Me) (6a )
Distances
Zr(1)-C(25)
Zr(1)-C(26)
Zr(1)-O(1)
2.241(4)
2.278(4)
2.003(3)
Zr(1)-O(2)
Zr(1)-N(1)
Zr(1)-N(2)
1.988(3)
2.504(3)
2.452(3)
F igu r e 6. Displacement ellipsoid plot (20% probablility)
of ZrMe2(O2NN′Me) (6a ) with hydrogen atoms omitted.
Angles
N(1)-Zr(1)-N(2)
N(1)-Zr(1)-O(1)
N(2)-Zr(1)-O(1)
N(1)-Zr(1)-O(2)
N(2)-Zr(1)-O(2)
O(1)-Zr(1)-O(2)
68.2(1)
80.7(1)
76.0(1)
77.2(1)
88.0(1)
156.4(1)
O(1)-Zr(1)-C(25) 103.05(14)
methyl groups of the axial NMe2 ligand therefore
attempts to balance between optimizing electronic and
steric factors (putting the non-H atoms of the axial
NMe2 ligand in the {N(1), N(2), N(3), N(4)} plane would
apparently place one of the methyl groups prohibitively
close to the pyridyl group ortho hydrogen atoms).
The solution NMR spectra of 5b are consistent with
the Cs symmetric structure found in the solid state.
There is no evidence for another isomer, unlike the
dichloride analogue ZrCl2(O2NN′tBu) (3b). The reso-
O(2)-Zr(1)-C(25)
N(1)-Zr(1)-C(26)
95.15(14)
96.81(13)
N(2)-Zr(1)-C(26) 163.18(14)
O(1)-Zr(1)-C(26)
O(2)-Zr(1)-C(26)
94.52(13)
96.34(13)
C(25)-Zr(1)-C(26) 101.8(2)
N(1)-Zr(1)-C(25) 160.6(2)
N(2)-Zr(1)-C(25) 93.95(14)
Ta ble 7. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for Zr Me2(O2NN′tBu ) (6b)
Distances
1
nances in both the H and 13C spectra of 5b are very
Zr(1)-C(37)
Zr(1)-C(38)
Zr(1)-O(1)
2.343(2)
2.267(2)
2.002(2)
Zr(1)-O(2)
Zr(1)-N(1)
Zr(1)-N(2)
2.009(2)
2.446(2)
2.497(2)
sharp, unlike those of 3b. There are two NMe2 group
environments (giving rise to two singlets for the two
1
distinct NMe2 ligands). The H NMR subspectrum for
Angles
t
O2NN′tBu shows two equivalent 2-O-3,5-C6H2 Bu2 moi-
O(1)-Zr(1)-O(2)
O(1)-Zr(1)-N(1)
O(2)-Zr(1)-N(1)
O(1)-Zr(1)-N(2)
O(2)-Zr(1)-N(2)
N(1)-Zr(1)-N(2)
O(1)-Zr(1)-C(37)
O(2)-Zr(1)-C(37)
158.85(7) N(1)-Zr(1)-C(37)
78.95(6) N(2)-Zr(1)-C(37)
80.65(7) O(1)-Zr(1)-C(38)
87.90(6) O(2)-Zr(1)-C(38)
79.45(7) N(1)-Zr(1)-C(38)
68.51(6) N(2)-Zr(1)-C(38)
99.63(7)
166.95(7)
96.98(8)
99.14(8)
154.99(8)
86.78(8)
eties; the CH2 protons adjacent to the pyridyl group
appear as a singlet, whereas the other CH2 group
protons give rise to a pair of mutually coupled doublets.
Attempts to convert the bis(dimethylamide) com-
pound 5b to the corresponding dichloride 3b by reaction
with Me3SiCl or HCl (1 M solution in diethyl ether) gave
only unidentified mixtures. Attempts to prepare a
dimethyl zirconium complex ZrMe2(O2NN′tBu) by reac-
tion of 5b with AlMe3 or AlMe3‚py in benzene were also
unsuccessful. However, the target dimethyl complexes
95.28(7) C(37)-Zr(1)-C(38) 105.32(9)
93.57(7)
analogous to that described for 3b and 5b above. The
phenoxide groups lie mutually trans to each other, and
the molecules possess approximate Cs symmetry. The
Zr-N and Zr-O distances are comparable to those of
5b but longer than in 3b, reflecting the better donor
nature of methyl groups in comparison with Cl and
NMe2. The 1H and 13C NMR spectra are consistent with
the solid-state structures and resemble those of Zr-
(NMe2)2(O2NN′tBu). The two methyl groups in 6a and
6b are in chemically different environments and give
rise to two distinct singlets in the range 1.2-0.8 ppm.
NOESY spectroscopy was used to assign the two dif-
ferent methyl group resonances, the most shielded
methyl groups lying trans to the pyridyl moiety.
t
ZrMe2(O2NN′R) [R ) Me (6a ) or Bu (6b)] could be fairly
easily obtained from the corresponding dichlorides
ZrCl2(O2NN′R) (3a , 3b) via transmetalation reactions
with methyllithium or methyl Grignard reagents (Scheme
2). Isolated yields are typically in the range 30-55%,
and the white crystalline products so prepared are
mildly air- and moisture-sensitive. Diffraction-quality
crystals of both 6a and 6b were obtained, and the
molecular structures are shown in Figures 6 and 7;
selected bond lengths and angles are presented in
Tables 6 and 7.
Both complexes 6a and 6b possess six-coordinate
metal centers in an approximately octahedral geometry
Reaction of ZrCl2(O2NN′Me) (3a ) with allylmagnesium
chloride gave intractable mixtures. However, the cor-

Zirconium Complexes of Diamine Ligands
Organometallics, Vol. 21, No. 7, 2002 1381
responding reaction of ZrCl2(O2NN′tBu) (3b) gave mod-
erate yields of a bis(allyl)zirconium derivative formu-
lated as Zr(η3-C3H5)2(O2NN′tBu) (7b). This compound is
highly fluxional and also fairly unstable in solution. The
latter feature meant that pure samples for elemental
analysis could not be obtained, and so 7b was charac-
1
terized by only H and 13C NMR, and also IR, spectros-
copy. The NMR spectra of 7b show resonances typical
of a Cs symmetric compound as illustrated. There are
two different allyl environments in the NMR spectrum.
At room temperature, one allyl ligand gives rise to an
apparent quintet (integrating as 1 H) at 6.25 ppm and
a time-averaged doublet (4 H) at 3.71; the other also
gives an apparent quintet (1 H, at 7.09 ppm) which is
associated with a broad signal (4 H) at ca. 3.83 ppm.
On warming the sample to ca. 60 °C, this latter
resonance sharpens and becomes a doublet; significant
sample decomposition also sets in rapidly at this tem-
perature. On cooling to -60 °C, this signal broadens into
the baseline (as does the doublet for the other allyl
ligand), but no new signals appear before the solvent
(toluene-d8) freezing point is reached. The appearance
of each allyl ligand’s resonances as an apparent quintet
and a doublet is typical of fluxional systems undergoing
rapid η3- T η1- T η3-bound allyl group interconver-
sions.47 The apparent quintet corresponds to the “cen-
tral” methine hydrogen; the NMR time scale-averaged
doublets arise from the four “terminal” methylene
hydrogens. We cannot tell if the allyl ligands in 7b are
η3- or η1-coordinated in the ground state. The solid-state
IR spectra are uninformative in this regard because the
absorptions for the O2NN′tBu ligand itself mask the
relevant region for allyl ligand absorptions. On balance
F igu r e 8. Displacement ellipsoid plot (20% probablility)
of Zr(CH2Ph)2(O2NN′Me) (10a ) with hydrogen atoms omit-
ted.
Ta ble 8. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for Zr (CH2P h )2(O2NN′Me) (10a )
Distances
Zr(1)-C(25)
Zr(1)-C(32)
Zr(1)‚‚‚C(26)
Zr(1)‚‚‚C(33)
2.300(3)
2.312(3)
3.006(2)
3.288(2)
Zr(1)-O(1)
Zr(1)-O(2)
Zr(1)-N(1)
Zr(1)-N(2)
1.990(2)
2.022(2)
2.447(2)
2.476(2)
we favor the formulation of 7b as Zr(η3-C3H5)2(O2NN′tBu
)
with two η3-bound allyl groups. Structurally character-
ized zirconium complexes possessing one,48 two,49 or
three50 η3-allyl ligands have been reported previously.
Both of the protio ligand H2O2NN′R (1a , 1b) undergo
smooth protonolysis reactions with the tetra-alkyl or
-benzyl zirconium compounds ZrR′4 (R ) CH2SiMe3,32
CH2CMe3, 33 or CH2Ph34,35). As shown in Scheme 2 these
reactions form ZrR′2(O2NN′R) [R′ ) CH2SiMe3 (8a , 8b),
CH2CMe3 (9a , 9b), or CH2Ph (10a , 10b); R ) Me (suffix
Angles
O(1)-Zr(1)-O(2)
O(1)-Zr(1)-N(1)
O(2)-Zr(1)-N(1)
O(1)-Zr(1)-N(2)
O(2)-Zr(1)-N(2)
N(1)-Zr(1)-N(2)
O(1)-Zr(1)-C(25)
157.25(7) N(2)-Zr(1)-C(25)
76.86(7) O(1)-Zr(1)-C(32)
80.42(7) O(2)-Zr(1)-C(32)
93.54(7) N(1)-Zr(1)-C(32)
77.33(7) N(2)-Zr(1)-C(32)
69.27(6) C(25)-Zr(1)-C(32) 100.9(1)
96.63(9) Zr(1)-C(25)-C(26) 103.2(2)
81.15(8)
100.17(9)
88.51(9)
110.06(8)
165.77(9)
O(2)-Zr(1)-C(25) 102.37(9) Zr(1)-C(32)-C(33) 118.9(2)
N(1)-Zr(1)-C(25) 149.04(8)
t
a ) or Bu (suffix b)], which are obtained in reasonable
10a possess approximately octahedrally coordinated
metal centers and Cs symmetry. The bond distances and
angles associated with the Zr(O2NN′Me) moiety are
comparable with those described above for other sys-
tems containing the Zr(O2NN′R) fragment. All of the
distances and angles for 10a are comparable to those
reported previously for 10b. In 10a the phenyl ipso
carbon C(26) of the “axial” benzyl group is loosely
associated [Zr(1)‚‚‚C(26) ) 3.006(2) Å] with the metal
center. The corresponding Zr-CH2-Ph angle for this
ligand is 103.2(2)°, which is significantly more acute
than for the “equatorial” benzyl ligand [Zr(1)-C(32)-
C(33) ) 118.9(2)°, Zr(1)‚‚‚C(33) ) 3.288(2) Å]. In 10b
the axial benzyl ligand also features a Zr‚‚‚Cipso interac-
tion, although in this complex the extent of interaction
is apparently greater [Zr-CH2-Ph ) 92.2(3)°; Zr‚‚‚Cipso
) 2.771(5) Å]. The origin of the loose Zr‚‚‚Cipso interac-
tions in 10a and 10b is likely to be electronic in nature
since the Zr centers in these compounds otherwise
possess only 12 valence electron counts (discounting any
likely O2p(π) f Zr4d(π) π-interactions). It is not clear why
to good isolated yields as white or pale yellow microc-
rystalline solids. NMR tube scale reactions showed that
8a , 8b, 10a , and 10b are also formed quantitatively by
the reaction of the dichloride complexes ZrCl2(O2NN′R)
(3a , 3b) with LiCH2SiMe3 or PhCH2MgCl in C6D6. While
this work was in progress, the synthesis and X-ray
structure of compound 10b was reported by Kol, Gold-
schmidt, and co-workers, but no other chemistry of the
O2NN′R ligands was described.22
For the purposes of comparison with 10b, we deter-
mined the X-ray crystal structure of the less sterically
crowded analogue Zr(CH2Ph)2(O2NN′Me) (10a ). The mo-
lecular structure is shown in Figure 8, and selected bond
distances and angles are given in Table 8. Molecules of
(47) Powell, P. Principles of Organometallic Chemistry, 2nd ed;
Chapman and Hall Ltd.: London, 1988.
(48) Pindado, G. J .; Thornton-Pett, M.; Bochmann, M. J . Chem. Soc.,
Dalton Trans. 1997, 3115.
(49) Erker, G.; Berg, K.; Angermund, K.; Kruger, C. Organometallics
1987, 6, 2620.
(50) Walther, D.; Fischer, R.; Friedrich, M.; Gebhardt, P.; Gorls, H.
Chem. Ber. 1996, 129, 1389.

1382 Organometallics, Vol. 21, No. 7, 2002
Toupance et al.
the Zr‚‚‚Cipso interaction in 10b is stronger than in the
less sterically crowded homologue 10a , but the influ-
ences of intermolecular packing effects may be impor-
tant in these systems.
reaction of the dimethyl compounds 6a, 6b with B(C6F5)3
in the presence of THF gave only ill-defined mixtures.
The H and 13C NMR spectra of all the compounds
1
ZrR′2(O2NN′R) (8a -10b) are fully consistent with the
Cs-symmetrical structures depicted in Scheme 2 and the
structures found in the solid state for 10a and 10b. As
for the dimethyl compounds ZrMe2(O2NN′R) (6a , 6b) the
two alkyl groups in 8a -10b are in chemically inequiva-
lent sites and give rise to two different sets of resonances
in the NMR spectra. One-dimensional NOE experiments
were used to assign unambiguously the two alkyl groups
(in each compound an NOE interaction is observed
between the pyridyl group ortho hydrogen and the CH2
group of the cis-alkyl substituent). By analogy with the
dimethyl complexes 6a and 6b, the CH2 protons of the
alkyl groups trans to pyridyl in 8a -10b are in all cases
the more shielded.
In addition, the 13C data for the CH2Ph groups of 10a
and 10b appear to reflect the slight η2-coordination (i.e.,
through Zr-CH2 and Zr‚‚‚Cipso interactions) of the cis
(with respect to pyridyl) benzyl groups. The Cispo reso-
nances for the weakly η2-bound cis benzyl groups appear
at 146.4 ppm in both 10a and 10b, whereas those for
the trans benzyls appear at 149.3 and 149.9 ppm,
respectively. We note that there is a much smaller
difference between the cis and trans CH2 group carbons
(cis to pyridyl: 65.3 and 67.6; trans to pyridyl: 65.6 and
67.0, for 10a and 10b respectively); furthermore, while
the differences between cis and trans benzyl Cipso
chemical shifts are ca. 3-3.5 ppm, the differences
between other pairs of ring carbon shifts (namely ortho,
meta, and para) are in the range 0.1-2.0 ppm.
Screening of the new dichloride (3a , 3b) or dibenzyl
(10a , 10b) or dimethyl (6b) complexes for ethylene
polymerization (toluene solvent with 5-7 atm pressure
C2H4) in the presence of methylaluminoxane (for 3a , 3b
and 10b; Zr:Al ratio ca. 1:1500) or B(C6F5)3 (for 6b and
10a , 10b; Zr:B ratio ca. 1:1) were effectively unsuccess-
ful, and only trace amounts of polymer were obtained.
We note that Kol and Goldschmidt22 have reported
the successful polymerization of 1-hexene with 10b. We
attribute the difference between our results (negative,
i.e., attempted ethylene polymerization in toluene) and
theirs to the fact that these authors carried out their
polymerizations in neat 1-hexene (for 10b: activity 5700
g poly(1-hexene) mmol-1 h-1 with Mw/ Mn ) 4.5); on
dilution of the 1-hexene monomer to 30% 1-hexene/70%
heptane the activity dropped by an order of magnitude
to 650 g mmol-1 h-1. There is a larger dilution effect in
our case using 5-7 bar C2H4 (headspace pressure), and
so despite the fact that R-olefins intrinsically give lower
polymerization rates, the dilution effects in our screen-
ing experiments possibly outweigh the expected higher
activity of ethylene over 1-hexene.
1H NMR NOE analyses of 11a , 11b established that
the benzyl groups in both cations are positioned cis to
1
the pyridyl donor group. The H and 19F NMR spectra
of the previously reported51 anion [PhCH2B(C6F5)3] in
11a , 11b suggest that there is no significant interaction
between it and the cation.52 The 13C NMR data for the
zirconium-bound benzyl groups in 11a , 11b suggest an
interaction between the ipso carbons and the cationic
zirconium centers, with the ispo carbon resonances
appearing ca. 10 ppm upfield of the analogous positions
in the dibenzyls 10a , 10b (the other resonances for the
CH2Ph groups of 11a , 11b appear downfield of them).
Indeed, on the basis of the X-ray structures of the
neutral dibenzyl complexes 10a , 10b it would appear
likely that such interactions would exist also in the [Zr-
(CH2Ph)(THF)(O2NN′R)]+ cations of 11a , 11b. Since it
is only the cis-positioned benzyl groups in both 10a , 10b
that exhibit a Zr‚‚‚Cipso interaction, we believe (i) that
this helps to account for the observation that the
remaining benzyl group preferentially occupies the cis
coordination site (although other factors such as the
greater trans labilizing effect of the pyridyl N-donor may
also contribute) and (ii) that the intramolecular stabi-
lization through an ipso carbon interaction may explain
why stable cationic complexes can be prepared from the
dibenzyl complexes 10a , 10b but not from the dimethyl
homologues 6a , 6b.
Con clu sion s
The readily available H2O2NN′R (1a , 1b) and Na2O2-
NN′R (2a , 2b) provide useful entry points to new
organometallic and coordination complexes of zirconium.
A series of six- or eight-coordinate derivatives have been
prepared and crystallographically characterized. At-
tempts to generate catalytically active systems for the
polymerization of ethylene were unsuccessful, although
THF-stabilized benzyl cations have been identified. We
are continuing to explore the early transition metal
chemistry of the O2NN′R ligand systems, and this work
will be reported in due course.
Ack n ow led gm en t. We thank the EPSRC (student-
ship to B.R.T.), Leverhulme Trust (postdoctoral fellow-
ship to S.R.D.), and European Commision (Marie Curie
Fellowship to T.T.) for support of this work.
Su p p or tin g In for m a tion Ava ila ble: X-ray crystallo-
graphic files in CIF format for the structure determinations
of 3a , 3b, 4a , 5b, 6a , 6b, and 10a . This material is available
free of charge via the Internet at http://pubs.acs.org.
Attempts to generate stable cationic organozirconium
complexes with B(C6F5)3 on an NMR tube scale from
the dimethyl or dibenzyl species ZrR′2(O2NN′R) (6a , 6b
or 10a , 10b) gave only ill-defined mixtures. However,
reaction of Zr(CH2Ph)2(O2NN′R) (10a, 10b) with B(C6F5)3
in the presence of THF (eq 2) gave the fully character-
ized cationic complexes [Zr(CH2Ph)(THF)(O2NN′R)]+ as
the [PhCH2B(C6F5)3]- salts (11a , 11b). In contrast, the
OM010982W
(51) J ime´nez Pindado, G.; Thornton-Pett, M.; Hursthouse, M. B.;
Coles, S. J .; Bochmann, M. J . Chem. Soc., Dalton Trans. 1999, 1663.
(52) Horton, A. D. Organometallics 1996, 15, 2675.