C O M M U N I C A T I O N S
References
(1) (a) Gemel, G.; Steinke, T.; Cokoja, M.; Kempter, A.; Fischer, R. A. Eur.
J. Inorg. Chem. 2004, 4161 (b) Cowley, A. H. Chem. Commun. 2004,
2369 and references therein.
(2) (a) Cui, C.; Roesky, H. W.; Schmidt, H.-G.; Noltemeyer, M.; Hao, H.;
Cimpoesu, F. Angew. Chem., Int. Ed. 2000, 39, 4274. (b) Hardman, N.
J.; Eichler, B. E.; Power, P. P. Chem. Commun. 2000, 1991. (c) Hill, M.
S.; Hitchcock, P. B.; Pongtavornpinyo, R. Dalton Trans. 2005, 273. (d)
Cheng, Y.; Hitchcock, P. B.; Lappert, M. F.; Zhou, M. Chem. Commun.
2005, 752.
(3) (a) Baker, R. J.; Farley, R. D.; Jones, C.; Kloth, M.; Murphy, D. M. Dalton
Trans. 2002, 3844. (b) Schmidt, E. S.; Jockisch, A.; Schmidbaur H. J.
Am. Chem. Soc. 1999, 121, 9758.
(4) Baker, R. J.; Jones, C. Coord. Chem. ReV. 2005, 249, 1857.
(5) Despagnet-Ayoub, E.; Grubbs, R. H. J. Am. Chem. Soc. 2004, 126, 10198.
(6) Jones, C.; Junk, P. C.; Platts, J. A.; Rathmann, D.; Stasch, A. Dalton
Trans. 2005, 2497.
Figure 1. Molecular structure of 1. Relevant bond lengths (Å) and angles
(deg): Ga(1)-N(1) 2.087(2), Ga(1)-N(2) 2.095(2), C(1)-N(1) 1.350(3),
C(1)-N(2) 1.349(3), C(1)-N(3) 1.373(3); N(1)-Ga(1)-N(2) 63.77(7),
N(1)-C(1)-N(2) 109.9(2), N(1)-C(1)-N(3) 125.1(2), N(2)-C(1)-N(3)
125.1(2), Ga(1)-N(1)-C(1) 93.33(14), Ga(1)-N(2)-C(1) 93.02(14).
Relevant bond lengths (Å) and angles (deg) for 2: In(1)-N(1) 2.298(2),
In(1)-N(2) 2.298(2), C(1)-N(1) 1.345(3), C(1)-N(2) 1.351(3), C(1)-N(3)
1.382(3); N(1)-In(1)-N(2) 58.06(6), N(1)-C(1)-N(2) 111.70(18), N(1)-
C(1)-N(3) 124.22(19), N(2)-C(1)-N(3) 124.08(19), In(1)-N(1)-C(1)
95.17(13), In(1)-N(2)-C(1) 95.03(13).
(7) Jones, C.; Junk, P. C.; Kloth, M.; Proctor, K. M.; Stasch, A. Polyhedron.
In press.
(8) The use of bulky backbone substituents to facilitate N,N-chelation of
amidinate ligands is well-known; see for example: Schmidt, J. A. R.;
Arnold, J. Organometallics 2002, 21, 2306 and references therein.
(9) Emsley, J. The Elements, 2nd ed.; Clarendon Press: Oxford, 1995.
(10) 1: Yield 35%. Mp 158-159 °C dec. 1H NMR (400 MHz, C6D6) δ 0.80-
0.93 (m, 8 H, CH2), 1.52 (d, J ) 6.8 Hz, 12 H, CH(CH3)2), 1.55 (d, J )
6.8 Hz, 12 H, CH(CH3)2), 1.40-1.63 (m, 12 H, CH2), 3.73 (overlapping
m, 4 H, CH(CH3)2 and 2 H, CHN), 7.04-7.42 (m, 6 H, ArH); 13C NMR
(100.6 MHz, C6D6) δ 22.3 (CH2), 26.2 (CH(CH3)2), 27.6 (CH(CH3)2),
28.9 (CH(CH3)2), 33.2 (CH2), 36.0 (CH2), 58.8 (HCN), 123.9, 124.4, 143.7,
145.9 (ArC), 174.2 (CN3); IR (Nujol) ν (cm-1) 1611 (s), 1583 (m), 1258
(m), 1163 (m); MS (EI/70 ev) m/z: 611.3 (M+, 3%), 500.3 (GisoH+
-
C3H7, 40%); Acc. mass MS/EI, calcd for C37H5669Ga1N3: 611.3725,
found: 611.3725; anal. calcd (%) for C37H56Ga1N3: C 72.54, H 9.21, N
6.86; found: C 71.93, H 9.28, N 6.98; 2: yield 48%. Mp 168-169 °C
dec. 1H NMR (400 MHz, C6D6) δ 0.61-0.88 (m, 8 H, CH2), 1.23 (d, J
) 6.8 Hz, 12 H, CH(CH3)2), 1.33 (d, J ) 6.8 Hz, 12 H, CH(CH3)2), 1.13-
1.50 (m, 12 H, CH2), 3.45 (m, 2H, CHN), 3.55 (sept, J ) 6.8 Hz, 4 H,
CH(CH3)2), 6.83-7.20 (m, 6 H, ArH); 13C NMR (100.6 MHz, C6D6) δ
22.5 (CH2), 26.4 (CH(CH3)2), 27.7 (CH(CH3)2), 28.6 (CH(CH3)2), 33.2
(CH2), 36.2 (CH2), 59.2 (HCN), 123.5, 124.0, 142.9, 144.3 (ArC), CN3
not observed; IR (Nujol) ν (cm-1) 1609 (s), 1584 (m), 1253 (m), 1157
(m); MS (EI/70 ev) m/z: 657.4 (M+, 6%), 500.3 (GisoH+ - C3H7, 36%);
Acc. mass MS/EI, calcd for C37H56In1N3: 657.3508, found: 657.3502;
anal. calcd (%) for C37H56In1N3: C 67.57, H 8.58, N 6.39; found: C 67.46,
H 8.75, N 6.51; 3: yield 68%. Mp 184-185 °C dec. 1H NMR (400 MHz,
C6D6) δ 1.15-2.44 (m, 20 H, CH2), 1.27 (d, J ) 6.8 Hz, 12 H, CH-
(CH3)2), 1.55 (d, J ) 6.8 Hz, 12 H, CH(CH3)2), 3.34 (m, 2H, CHN), 3.73
(sept, J ) 6.8 Hz, 4 H, CH(CH3)2), 6.92-7.43 (m, 6 H, ArH); 13C NMR
(100.6 MHz, C6D6) δ 22.8 (br, CH2), 25.1 (br CH(CH3)2), 25.8 (br, CH-
(CH3)2), 26.2 (br, CH(CH3)2), 26.5 (br, CH2), 32.0 (br, CH2), 56.9 (HCN),
120.5, 123.4, 141.1, 144.0 (br, ArC), CN3 not observed; IR (Nujol) ν
(cm-1) 1613 (s), 1583 (m), 1259 (m), 1152 (m); MS (EI/70ev) m/z: 747.3
(M+, 3%), 500.3 (GisoH+ - C3H7, 38%); Acc. mass MS/EI, calcd for
Figure 2. (a) HOMO and (b) LUMO of [:Ga{η2-N,N′-(Ph)NC(NMe2)N-
(Ph)}].
2). Although the metal center of each has high s-character (M )
Al 3s1.853p0.41, Ga 4s1.904p0.37, In 5s1.905p0.36), what p-character there
is, is largely associated with the metal py orbital. This gives the
lone pairs sp-character and their observed directionality. The
heterocycles have significant HOMO-LUMO gaps (M ) Al 61.8,
Ga 67.4, In 63.5 kcal mol-1) which, although considerably less
than the energy gaps calculated for the analogous orbitals of related
six-membered heterocycles (e.g. [:M{[N(Ar)C(Me)]2CH}], M )
Al 91.5, Ga 102.9, In 98.5 kcal mol-1),2c,13 suggest they will be
good σ-donors but weak π-acceptor ligands. There is almost no
overlap of the N p-orbital lone pairs with the metal pz orbitals, and
the N-M bonds have a high ionic character (e.g. NBO charges Ga
+0.71, N -0.75; Wiberg Ga-N bond index 0.23).
C
37H56Tl1N3: 747.4213, found: 747.4212; anal. calcd (%) for C37H56
-
Tl1N3: C 59.47, H 7.55, N 5.62; found: C 59.69, H 7.73, N 5.85.
(11) Crystal data for 1: C37H56GaN3, triclinic, P1h, a ) 9.6735(19) Å, b )
10.597(2) Å, c ) 17.818(4) Å, R ) 107.00(3)°, â ) 95.17(3)°, γ ) 97.82-
(3)°, V ) 1714.1(6) Å3, Z ) 2, Dcalc ) 1.187 g cm-3, µ(Mo KR) ) 0.831
mm-1; 7006 unique reflections were collected on an Enraf-Nonius Kappa
CCD diffractometer at 150(2) K (3.0 < θ < 26.5°), R1 ) 0.0461 (I >
2σI), wR2 ) 0.1071 (all data); Crystal data for 2: C37H56InN3, triclinic,
P1h, a ) 9.787(2) Å, b ) 10.556(2) Å, c ) 17.863(4) Å, R ) 107.14(3)°,
â ) 95.00(3)°, γ ) 97.81(3)°, V ) 1731.3(6) Å3, Z ) 2, Dcalc ) 1.262 g
cm-3, µ(Mo KR) ) 0.710 mm-1; 7519 unique reflections were collected
on an Enraf-Nonius Kappa CCD diffractometer at 150(2) K (3.0 < θ <
27.0°), R1 ) 0.0354 (I > 2σI), wR2 ) 0.0838 (all data); Crystal data for
In summary, the first examples of four-membered group 13
metal(I) N-heterocyclic carbene analogues have been prepared.
Theoretical studies suggest they will make novel ligands and that
the corresponding Al(I) heterocycle may be experimentally acces-
sible.
3: (C6H14
) : C40H63TlN3, monoclinic, P21/c, a ) 10.565(2) Å, b )
0.5
30.240(6) Å, c ) 12.371(3) Å, â ) 109.05(3)°, V ) 3735.9(13) Å3, Z )
4, Dcalc ) 1.405 g cm-3, µ(Mo KR) ) 4.353 mm-1; 7732 unique reflections
were collected on an Enraf-Nonius Kappa CCD diffractometer at 150(2)
K (3.0 < θ < 26.5°), R1 ) 0.0295 (I > 2σI), wR2 ) 0.0592 (all data).
(12) Aelts, S. L.; Coles, M. P.; Swenson, D. C.; Jordan, R. F. Organometallics
1998, 17, 3265.
Acknowledgment. We thank The Leverhulme Trust for funding
(A.S.) and the EPSRC mass spectrometry service.
(13) For related theoretical studies on five- and six-membered group 13 metal-
(I) heterocycles see: (a) Schoeller, W. W.; Eisner, D. Inorg. Chem. 2004,
43, 2585. (b) Sundermann, A.; Reiher, M.; Schoeller, W. W. Eur. J. Inorg.
Chem. 1998, 305. (c) Hardman, N. J.; Phillips, A. D.; Power, P. P. ACS
Symp. Ser. 2002, 822, 2. (d) Reiher, M.; Sundermann, A. Eur. J. Inorg.
Chem. 2002, 1854.
Supporting Information Available: Full details of the X-ray
crystallographic studies of 1-3, full details of the DFT calculations,
and full synthetic details for 1-3.
JA057967T
9
J. AM. CHEM. SOC. VOL. 128, NO. 7, 2006 2207