Inorganic Chemistry
Article
was filtered and then concentrated until incipient crystallization under
reduced pressure. After gentle warming to redissolve the solids, the
solution was cooled to −30 °C for several days to afford orange
crystals (128 mg, 0.178 mmol, 86%). 1H (500 MHz): δ 11.46 (s, As
CH, 1 H), 7.93 (t, C6H5, 2 H), 7.53 (d, C6H5, 2 H), 7.24 (t, C6H5, 2
H), 7.19 (t, C6H5, 2 H), 7.08 (t, C6H5, 2 H), 5.15 (s, CH2, 2 H), 3.17
(t, CH2, 6 H), 2.25 (t, CH2, 6 H), 0.15 (s, CH3, 27 H). 13C{1H}
(125.8 MHz): δ 251.4 (s, AsC); 134.3 (s, C6H5), 133.3, (s, C6H5),
126.9 (s, C6H5), 126.2 (s, C6H5), 64.2 (s, CH2), 59.4 (s, CH2), 46.7 (s,
CH2), 1.24 (s, CH3). IR 3051 w, 2948 m, 2887 w, 2845 m, 1642 w,
1574 w, 1475 w, 1451 w, 1330 m, 1299 w, 1242 s, 1183 m, 1155 w,
1103 m, 1051 m, 1019 m, 996 s, 925 m, 825 s, 785 m, 744 m, 731 s,
689 m, 641 m, 622 m, 561 m, 456 m, 430 m, 408 m. Anal. Calcd for
C29H52N5AsSi3Zr: C, 48.30; H, 7.27; N, 9.71. Found: C, 47.92; H,
7.36; N, 9.44.
1.974(2) Å as well as the angles about arsenic are inconsistent
with As−C multiple bond character while C(16)−N(5) =
1.285(1) Å is consistent with an imine functionality.
Isocyanide 1,1-insertion reactions with group 4 arsenido
complexes are known. The first example was reaction of
phenylisocyanide with Cp′2HfCl[As(SiMe3)2] as reported by
Hey-Hawkins.9b The structural similarities of that hafnium
compound and 9 are high. More important, the prevalence of
these 1,1-insertion reactions argue for their intermediacy in the
formation of arsaalkenes at primary arsenido complexes.
CONCLUSIONS
■
Insertion of isocyanides into Zr−As bonds yields iminoacyl
products that are unstable with respect to rearrangement to
afford arsaalkene products for primary arsenide ligands. This
stands in contrast to literature examples of isocyanide insertion
into Zr−As bonds that yield stable iminoacyl products for
secondary arsines. Indeed this is a second example in which
zirconium arsenide chemistry significantly changes between
primary and secondary arsines. These observations imply that
rich reaction chemistry of M−As bonds may yet be available
upon further exploration. This reaction type, a net coupling of
arsines with isocyanides at zirconium, appears to be a general
transformation based on the examples provided and may
represent the basis for new, metal-mediated synthetic strategies
to multiple bonding in the main group.
(N3N)Zr[N(Mes)CHAsPh] (5). A 2 mL ethereal solution of
mesitylisocyanide (41 mg, 0.282 mmol) was added dropwise to a 5 mL
ethereal solution of 2 (170 mg, 0.281 mmol) cooled to −30 °C in the
dark. The resultant red-orange solution was heated to 40 °C for 20
min, filtered, then concentrated until incipient crystallization under
reduced pressure. After gentle warming to redissolve the solids, the
solution was cooled to −30 °C for several days to afford orange
crystals. Analytically pure material was given by dissolving the crystals
in benzene followed by filtration of the solution though Celite and
lyophylization, presumed to remove ether trapped in crystallization, to
1
afford a red-orange powder (205 mg, 0.274 mmol, 97%). H (500
MHz): δ 11.54 (s, AsCH, 1 H), 7.98 (d, C6H5, 2 H); 7.24 (t, C6H5,
2 H), 7.13 (m, obscured by solvent), 6.92 (s, C6Me3H2, 2 H), 3.19 (t,
CH2, 2 H), 2.63 (s, o-CH3, 6 H), 2.26 (t, CH2, 6 H), 2.17 (s, p-CH3, 3
H), 0.17 (s, CH3, 27 H). 13C{1H} (125.8 MHz): δ 214.3 (s, AsCH),
141.2 (s, Ar), 138.3 (s, Ar), 134.1 (s, Ar), 131.5 (s, Ar), 131.4 (s, Ar),
129.3 (s, Ar), 128.4 (s, Ar), 68.4 (s, CH2); 49.5 (s, CH2), 23.9 (s, o-
CH3), 23.8 (s, o-CH3), 13.8 (s, p-CH3), 0.08 (s, CH3). One aryl
resonance was not observed, presumably obscured by solvent. IR:
3059 w, 2949 w, 2893 w, 2850 w, 1476 w, 1395 w, 1348 w, 1309 w,
1246 m, 1183 w, 1146 w, 1125 m, 925 m, 891 m, 830 s, 782 s, 733 s,
674 m, 539 m, 471 m, 435 m. Anal. Calcd for C31H56N5AsSi3Zr: C,
49.70; H, 7.53; N, 9.35. Found: C, 50.30; H, 8.23; N, 9.00.
EXPERIMENTAL DETAILS
■
Reactions were performed under a purified nitrogen atmosphere using
dry, oxygen-free solvents in an M. Braun glovebox or by standard
Schlenk techniques. Celite-454 was heated to a temperature above 180
°C under dynamic vacuum for at least 8 h. Benzene-d6 was purchased
then degassed and dried over NaK alloy. Elemental analyses were
performed on an Elementar microCube. NMR spectra were recorded
with either a Bruker Avance III, Bruker ARX, or Varian 500 MHz
spectrometer in benzene-d6 and are reported with reference to residual
solvent resonances (δ = 7.16 and 128.0) unless otherwise noted.
Infrared spectra were collected on a Bruker Alpha FT-IR with an ATR
plate or a Perkin-Elmer System 2000 FT-IR spectrometer at a
resolution of 1 cm−1 with KBr plates.
(N3N)Zr[N(CH2Ph)CHAsMes] (6). A 2 mL solution of
benzylisocyanide (21 mg, 0.178 mmol) was cooled to −30 °C and
added to a 4 mL ethereal solution of 3 (112 mg, 0.174 mmol) at −30
°C in the dark. The reaction mixture was stirred in the dark while
warming to ambient temperature over 4 h. The resulting orange
solution was then filtered and concentrated to ∼2 mL before being
cooled to −30 °C for several days to afford orange-yellow crystals (103
Compounds 1, 3, and 8, and 9 were prepared using the literature
procedures.7,8 Mesitylisocyanide was prepared according to the
literature procedure for phenylisocyanide substituting 2,4,6-trimethy-
laniline.14 Diphenylarsine and mesitylarsine were prepared according
to literature procedure.8 Phenylarsine was prepared using a modified
version of that in the literature.15 All other chemicals were obtained
from commercial suppliers and dried or purified by conventional
means.
(N3N)ZrPhAsH (2). A −30 °C, 5 mL ethereal solution of PhAsH2
(197 mg, 1.28 mmol) was added dropwise to a 5 mL ethereal solution
of 1 (605 mg, 1.34 mmol) at −30 °C. The colorless solution was
stirred and allowed to warm to ambient temperature over 16.5 h. The
resulting red solution was filtered through Celite, concentrated to ∼2
mL, and then cooled to −30 °C for 24 h to afford yellow crystals (587
mg, 0.972 mmol, 76%). 1H (500 MHz): δ 7.91 (t, J = 7.05 Hz, C6H5, 1
H); 7.79 (d, J = 7.09 Hz, C6H5, 2 H); 7.11 (t, J = 7.44 Hz, C6H5, 2 H);
3.42 (s, AsH, 1 H); 3.17 (t, J = 5.00 Hz, CH2, 6 H); 2.09 (t, J = 5.00
Hz, CH2, 6 H); 0.27 (s, CH3, 27 H). 13C{1H} (125.8 MHz): δ 134.9
(s, C6H5); 128.5 (s, C6H5), 126.5 (s, C6H5), 123.9 (s, C6H5); 63.6 (s,
CH2); 47.5 (s, CH2); 0.9 (s, CH3). IR 2061 (νAsH) cm−1. Anal. Calcd
for C21H45N4AsSi3Zr: C, 41.76; H, 7.51; N, 9.28. Found: C, 41.41; H,
7.72; N, 9.23.
1
mg, 0.136 mmol, 78%). H (500 MHz): δ 10.95 (s, AsCH, 1 H),
7.60 (d, C6H6,2 H), 7.50 (t, C6H6, 2 H), 7.12 (d, C6H6, 2 H), 6.94 (s,
C6Me3H2, 2 H), 5.20 (s, CH2, 2 H), 3.11 (t, CH2, 2 H), 2.68 (s, CH3, 6
H), 2.34 (s, CH3, 3 H), 2.25 (t, CH2, 6 H), 0.11 (s, CH3, 27 H).
13C{1H} (125.8 MHz): δ 273.53 (s, AsC), 140.0 (s, Ar); 135.5 (s,
Ar), 135.0 (s, Ar), 134.8 (s, Ar), 131.6 (s, Ar), 129.1 (s, Ar), 128.3 (s,
Ar), 65.0 (s, CH2); 64.1 (s, CH2), 46.6 (s, CH2), 25.0 (s, o-CH3), 20.0
(s, p-CH3), 1.2 (s, CH3). One aryl resonance was not observed,
presumably obscured by solvent. IR: 3062 w, 2955 w, 2873 w, 1565 w,
1471 w, 1340 w, 1322 w, 1303 w, 1244 m, 1183 w, 1148 w, 1115 m,
925 m, 875 m, 828 s, 782 s, 732 s, 679 m, 531 m. Anal. Calcd for
C32H58N5AsSi3Zr: C, 50.36; H, 7.66; N, 9.18. Found: C, 50.51; H,
7.84; N, 9.02.
(N3N)Zr[N(Mes)CHAsMes] (7). A 2 mL solution of mesityliso-
cyanide (16 mg, 0.110 mmol) was cooled and added to a 3 mL
ethereal solution of 3 (68 mg, 0.105 mmol) at −30 °C in the dark. The
reaction mixture was stirred in the dark while warming to ambient
temperature over 5 h. The resulting yellow solution was then filtered
and concentrated to ∼2 mL before being cooled to −30 °C for 2 d to
1
afford yellow crystals (69 mg, 0.087 mmol, 82%). H (500 MHz): δ
11.01 (s, AsCH, 1 H); 6.96 (s, C6Me3H2, 2 H), 6.73 (s, C6Me3H2, 2
H), 3.21 (t, CH2, 2 H), 2.76 (s, CH3, 6 H), 2.71 (s, CH3, 6 H), 2.34 (s,
CH3, 3 H), 2.22 (t, CH2, 2 H); 2.17 (s, CH3, 3 H), 0.13 (s, CH3, 27
H). 13C{1H} (125.8 MHz): δ 262.2 (s, AsC) 144.6 (s, C6Me3H2),
143.2 (s, C6Me3H2), 138.7 (s, C6Me3H2), 137.1 (s, C6Me3H2), 134.5
(N3N)Zr[N(CH2Ph)CHAsPh] (4). A 2 mL ethereal solution of
benzylisocyanide (25 mg, 0.212 mmol) was added dropwise to a 5 mL
ethereal solution of 2 (125 mg, 0.207 mmol) cooled to −30 °C in the
dark and stirred for 2 h at ambient temperature. The resulting solution
D
dx.doi.org/10.1021/ic4012058 | Inorg. Chem. XXXX, XXX, XXX−XXX