F. Marchetti, G. Pampaloni, S. Zacchini
FULL PAPER
= 244 Hz, arom. CF), 142.0 (2JC,F = 11 Hz, arom. CO), 103.6 (2JC,F
and GC–MS, which revealed the presence of 1,2-dichloroethane,
= 17 Hz, arom. CH), 58.9 (OMe) ppm. 19F NMR (CDCl3): δ = phenol and 1-phenoxy-2-Cl-ethane, in ca. 2:7:3 ratio.
–132.5 (br., 2 F, arom. CF) ppm.
General Procedure for the Synthesis of MX5(L) [L = κ1-1,4-(OMe)2-
C6H4, X = F, M = Nb, 4a; L = κ1-1,4-(OMe)2C6H4, X = Cl, M =
2g: Orange (208 mg, 75% yield). C8H8Cl10F2O2Ta2 (890.57): calcd.
Nb, 4b; L = κ2-1,3-(OMe)2C6H4, X = Cl, M = Ta, 4c; L =
C 10.78, H 0.91, Cl 39.81, Ta 40.64; found C 10.83, H 0.83, Cl
39.66, Ta 40.71. 1H NMR (CDCl3): δ = 7.03 (br., 2 H, arom. CH),
4.13 (br. s, 6 H, OMe) ppm. 13C{1H} NMR (CDCl3): δ = 148.3
(1JC,F = 244 Hz, arom. CF), 142.0 (2JC,F = 11 Hz, arom. CO), 104.6
MeOC6H5, X = F, M = Nb, 4d; L = MeOC6H5, X = Cl, M = Nb,
4e]: A slight excess amount of the appropriate arene (0.55 mmol)
was added to a suspension of MX5 (0.50 mmol) in CH2Cl2 (10 mL),
and the resulting mixture was stirred for 2 h. The volatile materials
were removed in vacuo, and hence, the final product was obtained
as a solid upon crystallization from CH2Cl2/pentane at –20 °C.
(2JC,F = 17 Hz, arom. CH), 59.5 (OMe) ppm. IR (solid state): ν =
˜
2964 (w), 1500 (vs), 1445 (m), 1406 (m), 1215 (w-m), 1182 (s), 1131
(m-s), 938 (vs), 879 (vs), 821 (vs), 775 (s), 734 (s), 677 (s) cm–1. ΛM
= 0.45 Scm2 mol–1.
4a: Orange (187 mg, 91% yield). C8H10F5NbO2 (326.06): calcd. C
29.47, H 3.09, Nb 28.49; found C 29.55, H 3.03, Nb 28.20. 1H
2h: Pink (184 mg, 79% yield). C8H10Cl10O2Ta2 (854.59): calcd. C
3
NMR (CDCl3): δ = 7.50, 7.05 (d, JH,H = 9.52 Hz, 4 H, arom.
11.24, H 1.18, Cl 41.49, Ta 42.35; found C 11.12, H 1.23, Cl 41.22,
CH), 4.86 (s, 3 H, NbOMe), 3.87 (s, 3 H, OMe) ppm. 19F NMR
(CDCl3): δ = 150.0 (br. s, 5 F, NbF5) ppm.
1
Ta 42.64. H NMR (CDCl3): δ = 7.67–7.32 (m, 3 H, arom. CH),
4.70 (s, 6 H, OMe) ppm. 13C{1H} NMR (CDCl3): δ = 162.4 (arom.
CO); 131.1, 114.4, 108.3 (C6H4); 76.8 (OMe) ppm. IR (solid state):
4c: Red (225 mg, 86% yield). C8H10Cl5O2Ta (496.38): calcd. C
19.36, H 2.03, Cl 35.71, Ta 36.45; found C 19.27, H 1.97, Cl 35.44,
Ta 36.36. 1H NMR (CDCl3): δ = 7.44 (m, 1 H, arom. CH), 6.98
(m, 3 H, arom. CH), 4.72 (s, 3 H, NbOMe), 3.89 (s, 3 H, OMe)
ppm. 13C{1H} NMR (CDCl3): δ = 162.4, 160.3 (arom. CO), 131.0,
114.5, 114.0, 108.3 (arom. CH), 76.0, 56.4 (OMe) ppm.
ν = 2982 (w), 1638 (m), 1597 (w-m), 1504 (vs), 1471 (s), 1411 (m-
˜
s), 1324 (m-s), 1240 (vs), 1149 (s), 1091 (s), 1009 (vs), 830 (vs) cm–1.
ΛM = 0.50 Scm2 mol–1.
General Procedure for the Synthesis of (MX5)2[µ-κ2-{PhO(CH2)2-
OPh}] (X = F, M = Nb, 3a; X = F, M = Ta, 3b; X = Cl, M = Nb,
3c; X = Cl, M = Ta, 3d): A suspension of MX5 (0.45 mmol) in
CH2Cl2 (10 mL) was allowed to react with 1,2-diphenoxyethane
(0.20 mmol), and the resulting mixture was stirred for 5 h. Then,
the mixture was filtered, and the filtered solution was dried in
vacuo. The final product was obtained as a microcrystalline powder
upon crystallization of the residue from CH2Cl2/pentane at –20 °C.
4d: Orange (161 mg, 87% yield). C7H8F5NbO (296.04): calcd. C
28.40, H 2.72, Nb 31.38; found C 28.55, H 2.66, Nb 31.24. 1H
NMR (CDCl3): δ = 7.45–7.26 (5 H, arom. CH), 4.25 (s, 3 H, OMe)
ppm. 13C{1H} NMR (CDCl3): δ = 158.9 (arom. CO), 130.9, 125.0,
118.3 (arom. CH), 64.9 (OMe) ppm. 19F NMR (CDCl3): δ = 157.9
(br. s, 5 F, NbF5) ppm.
4e: Red (174 mg, 86% yield). C7H8Cl5NbO (378.31): calcd. C
3a: Orange (159 mg, 91% yield). C14H14F10Nb2O2 (590.06): calcd.
C 28.50, H 2.39, Nb 31.49; found C 28.36, H 2.06, Nb 30.67. H
NMR (CDCl3): δ = 7.45, 7.17 (br. m, 10 H, Ph), 4.64 (s, 4 H, CH2)
ppm. 13C{1H} NMR (CDCl3): δ = 158.7 (arom. CO), 131.0, 126.7,
119.0 (Ph), 73.1 (CH2) ppm. 19F NMR (CDCl3): δ = 157.8 (br. s,
10 F, NbF5) ppm.
1
22.22, H 2.13, Cl 46.86, Nb 24.56; found C 22.13, H 2.06, Cl 46.59,
1
Nb 24.71. H NMR (CDCl3): δ = 7.49–7.30 (5 H, arom. CH), 4.45
(s, 3 H, OMe) ppm. 13C{1H} NMR (CDCl3): δ = 162.2 (arom.
CO), 130.2, 126.8, 121.1 (arom. CH), 71.2 (OMe) ppm. IR (solid
state): ν = 2952 (w), 2946 (w), 1584 (m), 1482 (s), 1454 (m), 1199
˜
(w-m), 1136 (s), 1070 (m), 1020 (m), 941 (vs), 868 (m), 837 (m),
3b: Red (184 mg, 88% yield). C14H14F10O2Ta2 (766.14): calcd. C
21.95, H 1.84, Ta 47.24; found C 22.07, H 1.93, Ta 47.02. 1H NMR
(CDCl3): δ = 7.42, 7.13 (br. m, 10 H, Ph), 4.72 (s, 4 H, CH2) ppm.
13C{1H} NMR (CDCl3): δ = 161.3 (arom. CO), 128.6, 124.1, 117.0,
(Ph), 72.0 (CH2) ppm. 19F NMR (CDCl3): δ = 76.5 (br. s, 10 F,
TaF5) ppm.
788 (vs), 761 (vs), 695 (vs) cm–1.
Complex 4b was detected as follows: compound 2b (0.30 mmol), in
a solution of CDCl3 (0.75 mL) in an NMR tube, was treated with
acetone (0.35 mmol). Then the tube was sealed, and the resulting
mixture was analyzed by 1H NMR after 3 h: complexes NbCl5[1,4-
C6H4(OMe)2] (4b) and NbCl5(OCMe2)[5a] were found in about 1:1
3
ratio. 4b (orange). 1H NMR (CDCl3): δ = 7.65, 7.10 (d, 4 H, JH,H
3c: Orange (221 mg, 91% yield). C14H14Cl10Nb2O2 (754.61): calcd.
C 22.28, H 1.87, Cl 46.98, Nb 24.62; found C 21.79, H 1.92, Cl
= 9.5 Hz, arom. CH), 4.96 (s, 3 H, NbOMe), 3.89 (s, 3 H, OMe)
ppm.
1
46.66, Nb 24.31. H NMR (CDCl3): δ = 7.50, 7.36 (br. m, 10 H,
Ph), 4.79 (s, 4 H, CH2) ppm. 13C{1H} NMR (CDCl3): δ = 159.0
(arom. CO), 130.1, 124.0, 117.5 (Ph), 75.6 (CH2) ppm. IR (solid
Solutions of complexes 4d,e (0.40 mmol), in CDCl3 (0.80 mL) in-
side sealed NMR tubes, were heated at 90 °C (temperature of the
external oil bath) for 60 min. The resulting mixtures were treated
with water (ca. 3 mmol), causing precipitation of a colourless solid
from a solution. Hence, the solutions were analyzed by NMR and
GC–MS, which revealed the presence of PhOMe (from 4d), MeCl
and PhOH (from 4e), ratio 1:1.
Preparation of TaBr4[κ1-OC6H4(4-OMe)] (5a) and NbCl4[κ1-
OC6H3(Me)(4-OEt)] (5b) and the Reaction of NbCl5 with 1,2,4-Tri-
methoxybenzene: Compound MX5 (0.50 mmol) was suspended in
CH2Cl2 (10 mL) and treated with the appropriate arene
(0.52 mmol). The mixture was stirred overnight, then the final
product was obtained as a powder upon removal of the volatile
materials. The same reaction, performed in CDCl3 (0.75 mL), was
monitored via 1H NMR: clean formation of 5a,b, in nearly equi-
molar admixture with RX (R = Me, Et; X = Cl, Br), was completed
after 3 h.
state): ν = 3052 (w), 2948 (w), 1599 (s), 1585 (s), 1497 (m-s), 1483
˜
(s), 1453 (s), 1382 (w-m), 1293 (m), 1243 (vs), 1229 (vs), 1176 (s),
1155 (m-s), 1143 (m-s), 1087 (m), 1065 (m-s), 1042 (m), 940 (m),
923 (m), 903 (vs), 885 (vs), 871 (vs), 806 (s), 748 (vs), 730 (s), 690
(vs) cm–1. ΛM = 0.18 Scm2 mol–1.
3d: Orange (212, 84% yield). C14H14Cl10O2Ta2 (930.69): calcd. C
18.07, H 1.52, Cl 38.09, Ta 38.88; found C 17.99, H 1.63, Cl 37.50,
1
Ta 38.46. H NMR (CDCl3): δ = 7.66–7.08 (10 H, Ph), 4.85 (s, 4
H, CH2) ppm. 13C{1H} NMR (CDCl3): δ = 158.7 (ipso-Ph), 129.9,
125.0, 119.2 (Ph), 74.0 (CH2) ppm.
In a different experiment, a CDCl3 solution of 3c (0.25 mmol in
0.75 mL), inside a sealed NMR tube, was heated at 90 °C (tempera-
ture of the external oil bath) for 1 h. Then, the tube was opened,
and the mixture was treated with an excess amount water (ca.
5 mmol). The resulting light red solution was analyzed by NMR
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Eur. J. Inorg. Chem. 2010, 767–774