3.187 (t, CH2, 6 H), 2.234 (s, CH3, 12 H), 2.148 (t, CH2, 6 H),
2.067 (s, CH3, 3 H), 0.255 (s, CH3, 27 H).
Preparation of (AsMes)4 (10).
Method A - Catalytic dehydrocoupling. A PTFE-valved reaction
tube was charged with MesAsH2 (250 mg, 1.27 mmol), 9 (41 mg,
0.064 mmol), and 10 mL benzene. The resulting orange solution
was degassed, the tube was sealed, and the solution heated to
90 ◦C. After 6 d, the solution was frozen and lyophilized. The
residue was washed two times with cold hexanes (3 mL each). The
residue was extracted into toluene (4 mL). The toluene solution
was filtered and layered with 3 mL pentane. Upon cooling to
Preparation of MesAs(NMe2)2. A Schlenk flask was charged
with (NMe2)2AsCl (4 g, 20 mmol) and dissolved in 12 mL
of THF, and the resulting solution cooled to 0 ◦C. A THF
solution of MesMgBr, prepared by refluxing a THF solution
of bromomesitylene (3.1 mL, 20 mmol) with magnesium powder
(515 mg, 21.2 mmol) and decanting from excess Mg, was added
over a period of 10 min to the arsine. The resulting mixture
was allowed to warm to ambient temperature and stirred for
2 h. The volatile materials were removed under reduced pressure,
and the residue extracted into hexanes. The hexanes solution was
filtered and the hexanes distilled under reduced pressure to leave
MesAs(NMe2)2 (5.33 g, 18.9 mmol, 94%) as a nearly colorless
oil, which was used without further purification. 1H (C6D6,
500.1 MHz): d 6.765 (s, C6H2Me3, 2 H), 2.639 (s, CH3, 6 H), 2.596
◦
−30 C, yellow-orange crystals formed after 3 d (182 mg, 74%).
MS (m/z): 777.0, 776.0. (C6D6, 500.1 MHz): d 6.730 (s,C6Me3H2,
2 H), 2.659 (s, CH3, 6 H), 2.263 (s, CH3, 6 H). 13C (C6D6, 125.8
MHz): d 145.22 (s, C6Me3H2), 138.64 (s, C6Me3H2), 129.55 (s,
C6Me3H2), 126.31 (s, C6Me3H2), 25.04 (s, o-CH3), 21.16 (s, p-
CH3).
Method B - Reduction. A 25 mL round bottom flask was
charged with Mg powder (90 mg, 3.7 mmol). A 10 mL THF
solution of MesAsCl2 (400 mg, 1.56 mmol) was added to the
Mg at ambient temperature. Upon stirring, the solution gradually
became orange. After 4 h at ambient temperature, the solvent was
removed under reduced pressure, and the residue was extracted
with minimal toluene (ca. 4 mL). The toluene solution was filtered
and layered with 2 mL pentane. Upon cooling to −30 ◦C yellow-
orange crystals formed after 3 d (258 mg, 85%). Spectroscopic
data was the same as from Method A.
1
(s, CH3, 12 H), 2.108 (s, CH3, 3 H). 13C{ H} (C6D6, 125.8 MHz) :
d 143.34 (s, Ar), 130.50 (s, Ar), 129.10 (s, Ar), one aryl carbon
resonance was not observed, presumably obscured by residual
solvent, 42.24 (s, NCH3), 21.87 (s, CH3), 20.88 (s, CH3).
37
Preparation of MesAsH2
. A two-neck 250 mL Schlenk flask
was charged with MesAs(NMe2)2 (4.2 g, 15 mmol), and the arsine
was dissolved in 60 mL Et2O added via cannula. The solution was
cooled to −78 ◦C, and an ethereal solution of HCl (29.8 mL, 2.0 M)
was added slowly via syringe. A colorless precipitate formed. The
solution was allowed to gradually warm to ambient temperature.
After 2 h, the volatile materials were removed under reduced
pressure. The residue was slurried in 60 mL Et2O, and the mixture
cooled to −78 ◦C. Solid LiAlH4 (720 mg, 19 mmol) was added
in small portions over 1 h via a solid-addition side arm. The
reaction was stirred at −78 ◦C for 2 h, then warmed gradually
to ambient temperature over ca. 8 h. The solvent was removed
under reduced pressure, and the solids extracted into hexanes. The
hexanes solution was filtered, and distilled to give MesAsH2 as a
colorless liquid (1.89 g, 9.69 mmol, 65%). 1H (C6D6, 500.1 MHz):
d 6.721 (s, C6Me3H2, 2 H), 3.167 (s, AsH, 1 H), 2.220 (s, CH3, 6 H),
2.102 (s, CH3, 3 H). MesAsD2 was prepared similarly substituting
LiAlD4 for LiAlH4.
Preparation of (N3N)Zr[C(AsPh2)=NCH2Ph] (11). A 5 mL
benzene solution of benzylisocyanide (17 mg, 0.14 mmol) was
added to a 5 mL benzene solution of 2 (97 mg, 0.14 mmol) at
ambient temperature. After 15 min, the yellow solution was frozen,
then lyophilized to yield a brown-yellow powder. This powder was
then dissolved in 5 mL Et2O, and the◦solution was filtered through
a bed of Celite then cooled to −30 C. After 2 d, yellow-brown
crystals formed (81 mg, 0.10 mmol, 72%). 1H NMR (C6D6, 500.1
MHz) d 7.908 (d, C6H5, 4 H), 7.379 (d, C6H5, 2 H), 7.119 (m,
C6H5, 1 H), 7.065 (m, C6H5, 4 H), 6.957 (m, C6H5, 2 H), 6.840 (d,
C6H5, 2 H), 5.168 (s, CH2Ph, 2 H), 3.258 (t, CH2, 6 H), 2.497 (t,
CH2, 6 H), 0.036 (s, CH3, 27 H). 13C{ H} (C6D6, 125.77 MHz):
1
d 273.53 (s, CN), 139.82 (s, C6H5), 137.32 (s, C6H5), 135.40 (s,
C6H5), 134.84 (s, C6H5), 129.00 (s, C6H5), 128.84 (s, C6H5), 128.56
(s, C6H5), 127.37 (s, C6H5), 65.06 (s, CH2), 62.14 (s, CH2), 47.40 (s,
CH2), 2.11 (s, CH3). IR (KBr, Nujol): 1653 s (mCN), 1576 s, 1559 s,
1540 s, 1506 s, 1456 m, 1243 m, 1052 m, 941 m, 832 m cm−1. Anal.
Calcd for C35H56N5AsSi3Zr: C, 52.73; H, 7.08; N, 8.78. Found: C,
52.30; H, 6.70; N, 8.65.
Preparation of (N3N)ZrAsHMes (9). A 25 mL round bottom
flask was charged with 1 (382 mg, 0.859 mmol) and 6 mL benzene.
A 2 mL benzene solution of MesAsH2 (166 mg, 0.849 mmol) was
added to the Zr solution causing an immediate color change to
bright yellow. The benzene solution was frozen and lyophilized to
give a yellow powder, which was dissolved in 6 mL of Et2O. The
solution was filtered and concentrated to ca. 3 mL under reduced
pressure. Cooling the solution to −30 ◦C gave bright yellow
=
Preparation of (N3N)Zr[N CPh(AsPh2)] (12). A 5 mL ben-
zene solution of benzonitrile (15.2 mg, 0.147 mmol) was added to
a 5 mL benzene solution of 2 (100 mg, 0.147 mmol) at ambient
temperature. After 30 min, the pink solution was frozen then
lyophilized to yield a pink powder. The powder was dissolved in
5 mL of Et2O, filtered and then cooled to −30◦C. After 2 d, pink
crystals were removed from the solution (98.4 mg, 0.126 mmol,
86%). 1H NMR (C6D6, 500.1 MHz) d 7.853 (t, C6H5, 2 H), 7.674
(m, C6H5, 4 H), 7.104 (t, C6H5, 4 H), 7.040 (m, C6H5, 4 H), 6.950
(t, C6H5, 1 H), 3.254 (t, CH2, 6 H), 2.434 (t, CH2, 6 H), 0.158
1
crystals in several crops (427 mg, 0.662 mmol, 78%). H (C6D6,
500.1 MHz): d 6.914 (s, C6Me3H2, 2 H), 3.312 (s, AsH, 1 H), 3.204
(t, CH2, 6 H), 2.665 (s, CH3, 6 H), 2.251 (s, CH3, 3 H), 2.132 (t,
1
CH2, 6 H), 0.265 (s, CH3, 27 H). 13C{ H} (C6D6, 125.8 MHz): d
143.12 (s, Ar), 139.47 (s, Ar), 132.89 (s, Ar), 127.54 (s, Ar), 64.46
(s, CH2), 47.76 (s, CH2), 27.41 (s, o-CH3), 20.97 (s, p-CH3), 1.20
(s, CH3). IR (KBr, Nujol): 2122 s (mAsH), 1558 m, 1464 s, 1372 m,
1330 m, 1262 s, 1245 s, 1144 m, 1046 s, 1013 s, 927 s, 892 m, 834 s,
776 s, 732 m, 673 m, 625 w, 568 m, 543 w, 457 m, 425 w cm−1. Anal.
Calcd for C24H51N4AsSi3Zr: C, 44.62; H, 7.96; N, 8.67. Found: C,
44.51; H, 7.87; N, 8.94.
1
(s, CH3, 27 H). 13C{ H} (C6D6, 125.77 MHz) d 185.0 (s, CN),
143.22 (s, C6H5), 141.07 (s, C6H5), 135.18 (s, C6H5), 134.87 (s,
C6H5), 129.39 (s, C6H5), 129.10 (s, C6H5), 128.70 (s, C6H5), 126.92
(s, C6H5), 61.48 (s, CH2), 47.51 (s, CH2), 1.61 (s, CH3). IR (KBr,
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The Royal Society of Chemistry 2008
Dalton Trans., 2008, 4488–4498 | 4495
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