= =
Synthesis of MesN C NMes (12). A mixture of 10 (624 mg,
Conclusions
2 mmol), HgO (870 mg, 4 mmol) and anhydrous MgSO4 (580 mg,
4.8 mmol) in 50 mL of toluene was refluxed overnight. After
cooling to room temperature, the reaction mixture was filtered
In summary, we have explored the possibility of synthesizing
guanidinate-supported boron(I) derivatives by reduction of two
new (guanidinate)boron dichlorides. Although the desired com-
pounds were not obtained, DFT and MP2 calculations on a model
system revealed the ground state is a singlet and that the HOMO-
LUMO gap may be sufficiently large to permit the future isolation
of the desired boron(I) species.
R
over Celiteꢀ and the filtrate concentrated to dryness to afford an
85% yield of the title compound as a colorless microcrystalline
solid. 1H NMR (CD2Cl2): d 6.89 (s, 4H, Ar–H), 2.40 (s, 12H, Ar–
CH3), 2.30 (s, 6H, Ar–CH3); 13C NMR (CD2Cl2): d 134.5 (Ar),
132.9 (Ar), 129.5 (Ar), 129.4 (Ar), 21.1 (Ar–CH3), 19.2 (Ar–CH3).
MS (CI+, CH4): m/z 278 (M + H). HRMS (CI, CH4) calcd. for
C19H23N2, 279.1861; found 279.1860.
Acknowledgements
We gratefully acknowledge the National Science Foundation
(Grant CHE-0240008) and the Robert A. Welch Foundation
(Grant F-0003) for support of this work.
= =
Synthesis of DippN C NDipp (13). Colorless crystals of 13
were prepared in 87% yield from 11 using the procedure described
1
above for 12. H NMR (CDCl3): d 7.39 (dd, 2H, Ar–H), 7.31
(d, 4H, Ar–H), 3.62 (sept, 4H, Ar–C(H)Me2), 1.41 (d, 24H, Ar–
CH(Me)2); 13C NMR (CDCl3): d 143.2 (Ar), 129.1 (Ar), 125.3 (Ar),
123.7 (Ar), 29.6 (Ar–C(H)Me2), 23.6 (Ar–CH(Me)2). MS (CI+,
CH4): m/z 363 (M + H). HRMS (CI, CH4) calcd. for C25H35N2
363.2800; found 363.2789.
Notes and references
1 E. S. Schmidt, A. Jockisch and H. Schmidbaur, J. Am. Chem. Soc.,
1999, 121, 9758.
2 R. J. Baker, R. D. Farley, C. Jones, M. Kloth and D. M. Murphy,
J. Chem. Soc., Dalton Trans., 2002, 3844.
3 R. J. Baker and C. Jones, Coord. Chem. Rev., 2005, 249, 1857.
4 Y. Segawa, M. Yamashita and K. Nozaki, Science, 2006, 314, 5796.
5 Y. Segawa, M. Yamashita and K. Nozaki, Angew. Chem., Int. Ed., 2007,
46, 6710.
6 M. Yamashita, Y. Suzuki, Y. Segawa and K. Nozaki, J. Am. Chem.
Soc., 2007, 129, 9570.
7 C. Jones, P. C. Junk, J. A. Platts and A. Stasch, J. Am. Chem. Soc., 2006,
128, 2206.
8 E. Despagnet-Ayoub and R. H. Grubbs, J. Am. Chem. Soc., 2004, 126,
10198.
9 C. Cui, H. W. Roesky, H.-G. Schmidt, M. Noltemeyer, H. Hao and F.
Cimpoesu, Angew. Chem., Int. Ed., 2000, 39, 4274.
10 N. J. Hardman, B. E. Eichler and P. P. Power, Chem. Commun., 2000,
1991.
11 M. S. Hill and P. B. Hitchcock, Chem. Commun., 2004, 1818.
12 M. S. Hill, P. B. Hitchcock and R. Pongtavornpinyo, Dalton Trans.,
2005, 273.
13 C.-H. Chen, M.-L. Tsai and M.-D. Su, Organometallics, 2006, 25, 2766.
14 M. Reiher and A. Sundermann, Eur. J. Inorg. Chem., 2002, 1854.
15 M. Reiher, O. Salomon and B. A. Hess, Theor. Chim. Acta, 2001, 107,
48.
16 G. A. Pierce, N. D. Coombs, D. J. Willock, J. K. Day, A. Stasch and S.
Aldridge, Dalton Trans., 2007, 4405.
17 M. Findlater, N. J. Hill and A. H. Cowley, Polyhedron, 2006, 25, 983.
18 K. Ogawa and M. Akazawa, Japanese Patent JP 04312568, 1992.
19 W. Weith, Ber. Dtsch. Chem. Ges., 1874, 7, 10; W. Weith, Ber. Dtsch.
Chem. Ges., 1874, 7, 1303.
20 V. H. Irngartinger and H.-U. Ja¨ger, Acta Crystallogr., Sect. B, 1978,
34, 3262; A. T. Vincent and P. J. Wheatley, J. Chem. Soc., Perkin Trans.
2, 1972, 1567.
21 A. Ansorge, D. J. Brauer, H. Bu¨rger, F. Do¨rrenbach, T. Hagen, G.
Pawlke and W. Weuter, J. Organomet. Chem., 1991, 407, 283.
22 N. J. Hill, M. Findlater and A. H. Cowley, Dalton Trans., 2005, 3229;
N. J. Hill, J. A. Moore, M. Findlater and A. H. Cowley, Chem. Commun.,
2005, 5462.
Synthesis of [Ph2NC{NMes}2]BCl2 (14). A stirred solution of
diphenylamine (339 mg, 2 mmol) in diethyl ether (20 mL) was
cooled to −78 ◦C and nBuLi (1 eq.) added via syringe. The reaction
mixture was allowed to warm to room temperature and stirred for
a further hour, at which point it was re-cooled to −78 ◦C and
an ethereal solution (10 mL) of 12 (558 mg, 2 mmol) was added.
The reaction mixture was once more allowed to warm to room
temperature following which it was stirred for 1 h. For a third
◦
time the solution was cooled to −78 C and BCl3 (2 mL, 1.0 M
solution in hexane, 1 eq.) was added via syringe. The reaction
mixture was then allowed to warm slowly to room temperature
and was stirred overnight. After filtration and solvent stripping,
14 was isolated as a white solid in 90% yield. 1H NMR (CD2Cl2):
d 6.93 (dd, 2H, Ar–H), 6.66 (m, 4H, Ar–H), 6.57 (m, 4H, Ar–H),
6.46 (s, 4H, Ar–H), 2.43 (s, 12H, Ar–CH3), 2.21 (s, 6H, Ar–CH3);
13C NMR (CD2Cl2): d 140.3 (Ar), 136.0 (Ar), 135.73 (Ar), 129.65
(Ar), 129.52 (Ar), 127.50 (Ar), 125.43 (Ar), 21.06 (Ar–Me), 20.26
(Ar–Me); 11B NMR (CD2Cl2): d 6.79. MS (CI+, CH4): m/z minor
528 (M + H), major 491 (M-Cl).
Synthesis of [Ph2NC{NDipp}2]BCl2 (15). Colorless needle-
like, crystals of 15 were prepared in 88% yield from 13 using the
1
same procedure that was described for 14. H NMR (CDCl3):
d 7.24 (m, 8H, Ar-H), 7.10 (m, 8H, Ar-H), 3.78 (sept, 2H, Ar–
C(H)Me2), 3.61 (sept, 2H, Ar–C(H)Me2), 1.41 (m, 24H, Ar–
CH(Me)2); 13C NMR (CDCl3): d 147.32 (Ar), 146.80 (Ar), 142.96
(Ar), 128.79 (Ar), 127.60 (Ar), 125.1 (Ar), 124.89 (Ar), 124.63
23 H. No¨th and B. Wrackmeyer, Nuclear Magnetic Resonance of Boron
(Ar), 123.48 (Ar), 29.35 (Ar–(C)HMe2), 23.45 (Ar–CH(Me)2); 11
B
Compounds, Springer Verlag, Berlin, 1978.
NMR (CDCl3): d 9.17. MS (CI+, CH4): m/z 612 (M + H). HRMS
24 G. M. Sheldrick, SHELL-PC, Version 5.03, Siemens Analytical
Instruments Inc., Madison, WI, USA, 1994.
(CI, CH4) calcd. for C37H44BCl2N3 611.3131; found 611.3123.
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