Notes and references
† 5: NMR (d6-benzene, 295 K), 1H d 7.16, 7.09 (m, 3H, C6H3), 5.69 [(s,
10H, C5H5)], 2.28 [s , 6H, C6H3(CH3)2], 1.52 [s, 9H, PCC(CH3)3] 31P{1H}
d 81.7. EI-MS m/z (%): 439 (20) [M]+, 339 (100) [M 2 PCCMe3]+.
Elemental analysis: Calc. for C23H28NPZr; C, 62.69; H, 6.40, N, 3.18.
Found: C, 62.41; H, 6.37, N, 3.12%.
‡ Crystal data: 5: C23H28NPZr, M = 440.6, monoclinic space group P21/c,
a = 11.622(3), b = 21.830(8), c = 8.389(4) Å, b = 107.01(3), U =
2035.3(13) Å3, Z = 4, Dc = 1.44 Mg m23, crystal dimensions 0.40 3 0.30
3 0.02 mm, T = 173(2) K, Mo-Ka, radiation l = 0.71073 Å. Data were
collected on an Enraf-Nonius CAD4 diffractometer and of the total 3811
reflections measured, 3563 unique (Rint = 0.042). Refinement on F2, wR2
= 0.138 (all data), R1 = 0.048 [for 2651 reflections with I > 2s(I)].
7: C19H32Cl2N2P2Ti, M = 469.2, monoclinic, space group P21/n, a =
12.728 (2), b = 12.170(1), c = 15.596(1) Å, b = 97.5(1)°, U = 2395.1(5)
Å3, Z = 4, Dc = 1.3 Mg m23, T = 173(2) K, Mo-Ka, radiation l =
0.71073 Å. Data were collected on an Enraf-Nonius CAD4 diffractometer
and of the total 7242 reflections measured, 6969 unique (Rint = 0.017).
Refinement on F2, wR2 = 0.095 (all data), R1 = 0.040 [for 5271 reflections
with I > 2s(I)]. CCDC 182/1184. See http:/www rsc.org/suppdata/cc/
1999/661/ for crystallographic files in .cif format.
Fig. 2 Molecular structure of [Ti{NButPCButPCBut}Cl2(py)]8. Selected
distances (Å) and angles (°): P(1)–N(2) 1.727(2), Ti–N(2) 1.880(2), P1–
C(1) 1.825(2), P(2)–C(1) 1.735(2), P(2)–C(2) 1.768(2), C(2)–P(1) 1.847(2),
Ti–N(1) 2.394(2), Ti–P(2) 2.784(2), Ti–C(2) 2.221(2), Ti–P(1) 2.442(1),
Ti–C(1) 2.439(2); Ti–N(2)–C(11) 148.31(14), Cl(2)–Ti–Cl(1) 109.57(2),
C(2)–P(1)–C(1) 80.86(8), C(1)–P(2)–C(2) 85.65(8). Displacement elip-
soids are shown at 50% probability level.
§ 6: NMR (d6-benzene, 295 K), 1H d 5.68 (s, 10H, C5H5), 1.31 [s , 9H,
NC(CH3)], 1.52 [s, 9H, PCC(CH3)3]. 31P{1H} d 64.1. EI-MS m/z (%): 391
(30) [M]+, 376 (20) [M 2 Me]+, 276 (55) [M 2 Me 2 PCCMe3]+.
¶ 7: NMR (d6-benzene, 295 K), 1H d 4.12, 3.8, 2.81 (3 3 m, 8H, CH2CH2),
1.5 [s, 9H, NC(CH3)], 1.48 [s, 9H, PC(CH3)], 0.2 (s, 9H, NSiMe3), 0.09 (s,
18H, NSiMe3). 13C{1H d 53.7, 51.6 (CH2CH2), 35.2 [d, NC(CH3), 3JPC 12.2
with the N, two Cl ions, P lone pair and the pyridine. As
expected the Ti–N(2) bond length [1.880(2) Å] in 8 is
considerably elongated when compared with the starting imide
complex 2 [1.705(3) Å] and the Ti–N(pyridine) bond length
[2.394(2) Å] is very long. The Ti–N–C(a) bond angle in 8
(148.3°) is typical for a metal–nitrogen double bond.
3
Hz], 34.4 [d, PCC(CH3)3, JPC 8 Hz] 2.5 [SiC(CH3)], 0.2 [SiC(CH3)].
31P{1H} d 209.4. EI-MS m/z (%): 536 (20) [M]+ , 436 (45) [M 2 (PCBut)]+.
The oily nature of this compound precluded satisfactory microanalysis.
∑ 8: NMR (d6-benzene, 295 K), 1H d 9.5, 6.78, 6.53 (m, 5H, NC5H5), 1.46
[s, 9H, NC(CH3)3], 1.32, 1.30 [s 3 2, 18H, PC(CH3)3]. 13C{1H} (d8-
toluene, 295 K): 198.3 (dd, PCP, 1JPC 61.95, 2JPC 29.9 Hz), 151.1, 123.2 (m,
Although no reaction intermediates have been spectroscop-
ically characterised, the formation of the TiC2P2N core in 8 is
presumed to proceed by sequential [2 + 2] cycloaddition of
ButCP with (i) the titanium–nitrogen double bond and (ii) the
resulting PNC double bond (Scheme 3).
2
NC5H5), 68.89 [d, NC(CH3)3, JPC 8.10 Hz], 41.33 [pseudo-t,
2
3
{PCC(CH3)3}2, JPC 6.50 Hz], 33.96 [pseudo-t, {PCC(CH3)3}2, JPC 4.97
Hz], 32.37 [d, NC(CH3)3, JPC 6.03 Hz]. 31P{1H} (d6-benzene, 295 K) d
3
296.5, 2139.5 (d 3 2, 2JPP 40.5 Hz). EI-MS m/z (%): 465 (85) [M]+, 389
(10) [M 2 py]+, 333 (12) [M 2 Py 2But)]+
.
** Similarly [Ti(h -C8H8)(NBut)] readily reacted with ButCP in toluene at
8
But
room temp. to afford, after recrystallisation from pentane, dark brown
Toluene 55 °C But
P
8
crystals of [Ti(h -C8H8)(P2C2But2NBut)] 9 in 71% yield. Although not
52 h
[2+2]
[Ti(NBut)Cl2(py)3]
P
N
P
But
But
N
shown here, the molecular structure of 9 has also recently been obtained and
reveals a common TiC2P2N core comfirming its structural significance for
this type of reaction.
ButCP
Ti
Lx'
[2+2]
2
But
Ti
+
Py
Cl
Cl
ButCP
8
1 F. Tabellion, A. Nachbauer, S. Leininger, C. Peters and M. Regitz,
Angew. Chem., Int. Ed., 1998, 37, 1233.
Scheme 3
2 P. A. Walsh, A. M. Baranger and R. G. Bergman, J. Am. Chem. Soc.,
1992, 114, 1708.
3 For a review of titanium imido chemistry, see: P. Mountford, Chem.
Commun., 1997, 2127 and references therein (Feature Article).
4 A J. Blake, P. E. Collier, S. C. Dunn, W.-S. Li, P. Mountford and O. V.
Shishkin, J. Chem Soc., Dalton Trans., 1997, 1549.
5 P. Mountford and F. G. N. Cloke, unpublished work.
6 A. J. Blake, S. C. Dunn, J. C. Green, N. M. Jones, A G. Moody and P.
Mountford, Chem. Commun., 1998, 1235.
7 F. G. N. Cloke, P. B. Hitchcock, J. F. Nixon, L. Nyulaszi, M. Regitz and
D. J. Wilson, unpublished work.
Interestingly, the course of the reactions involving complexes
of type 2 is also affected by the nature of the imido N-
substituent. Thus treatment of [Ti(NR)Cl2(py)3] (R = Ph, p-
MeC6H4, p-NO2C6H4 or Pri) with ButCP gave the previously
unknown 1,2,4-azadiphospholes P2C2But2NR. The molecular
structure of P2C2But2NPh has been determined and this new
class of heteroaromatic ring systems will be the subject of a
separate publication.6 The range of products obtained with
different metal and N-substituents indicates the possibility for a
rich and diverse derivative chemistry.
Philip Mountford is the Royal Society of Chemistry Sir
Edward Frankland Fellow for 1998–9.
Communication 9/00648F
662
Chem. Commun., 1999, 661–662
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