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R. Bondi et al. / Polyhedron 100 (2015) 192–198
4.2. Reactivity of NbCl5 with NHEt2: synthesis and isolation of
[NbCl4(NEt2)]2, 1, [NH2Et2][NbCl6], 2a
2.37; Cl, 35.93. Found: C, 42.47; H, 3.48; N, 2.29; Cl%, 35.80. IR
(solid state): = 1635w-m
cmꢁ1 1H NMR (CD3CN):
m
(
mC@N
)
.
d = 9.22 (s, 1H, HC@N); 7.94, 7.73, 7.46 (15H, Ph); 5.40, 5.23 (s,
4H, CH2) ppm. 13C NMR{1H} (CD3CN): d = 174.4 (HC@N); 136.9,
132.8–128.3 (Ph); 64.9, 56.7 (CH2) ppm. 93Nb NMR (CD3CN):
A suspension of NbCl5 (383 mg, 1.42 mmol) in CH2Cl2 (ca.
20 mL) was treated with NHEt2 (0.147 mL, 1.42 mmol). The mix-
ture was allowed to stir at room temperature for 40 h. The final
dark-red solution was concentrated to ca. 5 mL, layered with hex-
ane and settled down at ꢁ30 °C. A large crop of mixed dark-red (1)
and yellow (2a) crystals was collected after one week, then the
crystals were mechanically separated.
d = 6.8 (
In
D
a
m
½ = 2ꢂ102 Hz) ppm.
different experiment, NbCl5 (0.35 mmol), N(CH2Ph)3
(0.35 mmol), CD2Cl2 (0.6 mL) and CHCl3 (0.35 mmol) were intro-
duced into an NMR tube. The tube was sealed, briefly shaken in
order to homogenize the content, and then stored at room temper-
ature for one week. Subsequent NMR analysis revealed the pres-
ence of 3, [NH(CH2Ph)3]+ [d (1H, CD3CN) = 7.56, 7.33 (15H, Ph);
6.53 (br, 1H, NH); 4.42 (s, 6H, CH2) ppm; d (13C, CD3CN) = 131.4–
127.8 (Ph); 57.4 (CH2) ppm] and CHCl3 (approximate ratio
0.3:0.3:1). 93Nb spectrum (in CD3CN) exhibited resonances at 6.8
[NbCl4(NEt2)]2, 1: Yellow solid, yield 179 mg (41%). Anal. Calc. for
C4H10Cl4NNb: C, 15.66; H, 3.28; N, 4.56; Cl, 46.22. Found: C, 15.56;
H, 3.34; N, 4.51; Cl, 46.01%. 1H NMR (CD2Cl2): d = 3.38 (q, 2H,
3JHH = 6.85 Hz, CH2); 1.44 (m, 3H, CH3) ppm. 13C{1H} NMR (CD2Cl2):
d = 44.4 (CH2); 11.2 (CH3) ppm. 93Nb NMR (CD2Cl2): d = 214.1
(D
m
½ = 3ꢂ103 Hz) ppm.
(D
m
½ = 2ꢂ102 Hz) and ꢁ350 (
D
m
½ = 2ꢂ103 Hz) ppm.
[NH2Et2][NbCl6], 2a: Dark-red solid, yield 237 mg (44%). Anal.
Then the tube was opened and the content was transferred into
Calc. for C4H12Cl6NNb: C, 12.65; H, 3.18; N, 3.69; Cl, 56.01. Found:
C, 12.55; H, 3.07; N, 3.77; Cl, 55.87%. IR (solid state): = 3162m-br,
a Schlenk tube. The volatile materials were removed in vacuo. The
m
yellow-orange
v
residue
underwent
magnetic
analysis:
3103m (
m
N–H) cmꢁ1
.
1H NMR (CD2Cl2): d = 6.43 (br, 2H, NH2); 4.90
M = 4.81 ꢃ 10ꢁ5 cgsu.
3
(q, 2H, JHH = 6.85 Hz, CH2); 1.52 (m, 3H, CH3) ppm. 13C{1H} NMR
(CD2Cl2): d = 55.6 (CH2); 11.6 (CH3) ppm. 93Nb NMR (CD2Cl2):
4.5. Synthesis and isolation of [NHEt3][NbCl6], 4, and [NHEt3]2[NbCl6],
5
d = 8.0 (
In
D
a
m
½ = 2ꢂ102 Hz) ppm.
different experiment, NbCl5 (0.35 mmol), NHEt2
(0.35 mmol), CD2Cl2 (0.6 mL) and CHCl3 (0.35 mmol) were intro-
duced into an NMR tube. The tube was sealed, briefly shaken in
order to homogenize the content, and then stored at room temper-
ature for one week. Subsequent NMR analysis revealed the clean
presence of 1, 2a and CHCl3 (approximate ratio 0.4:0.5:1).
NEt3 (0.115 mL, 0.825 mmol) was added dropwise to a suspen-
sion of NbCl5 (230 mg, 0.851 mmol) in CH2Cl2 (15 mL). Immediate
colour change to dark-brown was observed, and the mixture was
allowed to stir at room temperature for additional 24 h. The final
mixture was filtered in order to remove a minor amount of solid.
The dark-brown solution was concentrated to ca. 5 mL, layered
with hexane and settled aside at ꢁ30 °C. An ochre yellow micro-
crystalline material was recovered after 48 h. Yield 87 mg (26%).
Anal. Calc. for C6H16Cl6NNb: C, 17.67; H, 3.95; N, 3.43; Cl, 52.16.
Found: C, 17.78; H, 3.84; N, 3.52; Cl, 52.03%. IR (solid state):
i
4.3. Synthesis and isolation of [NH3nPr][NbCl6], 2b, and [NH2 Pr2]
[NbCl6], 2c
General procedure: NbCl5, suspended in CH2Cl2 (ca. 15 mL), was
allowed to react with the appropriate amine for 48 h. The mixture
was filtered off in order to remove some solid, then it was layered
with hexane and settled aside at ꢁ30 °C for one week. Thus 2b,c
were recovered as microcrystalline materials. The crystallization
liquors were isolated and dried in vacuo: the resulting residues
were analyzed by IR (solid state) and NMR (CDCl3 solution), show-
ing the presence of mixtures of products which were not identified.
[NHn3Pr][NbCl6], 2b: Pale-yellow solid, from NbCl5 (250 mg,
0.925 mmol) and NH2nPr (0.076 mL, 0.924 mmol). Yield 74 mg
(22%). Anal. Calc. for C3H10Cl6NNb: C, 9.85; H, 2.76; N, 3.83; Cl,
58.16. Found: C, 9.66; H, 2.88; N, 3.77; Cl, 58.03%. IR (solid state):
m
= 3132 m (
1448s-sh, 1395m, 1354w, 1285w, 1171w, 1155w, 1056w,
1029m, 1009m, 832s, 807vs, 790s, 733s cmꢁ1 1H NMR (CD2Cl2):
mN–H), 3007w, 2988w, 2942w, 1599w, 1469s, 1455s,
.
d = 6.11 (br, 1H, NH); 3.29 (m, 6H, CH2); 1.45 (m, 9H, CH3) ppm.
13C{1H} NMR (CD2Cl2): d = 48.6 (CH2); 9.8 (CH3) ppm. 93Nb NMR
(CD2Cl2): d = 6.1 (
D
m
½ = 4ꢂ102 Hz) ppm.
The reaction of NbCl5 (290 mg, 1.07 mmol) with NEt3 (0.300 mL,
2.15 mmol) was carried out with a procedure analogous to that
described for the synthesis of 4. Crystallization from CH2Cl2/hex-
ane at ꢁ30 °C afforded red crystals of 5 suitable for X-ray analysis.
Yield 203 mg, 37%. Anal. Calc. for C12H32Cl6N2Nb: C, 28.26; H, 6.32;
N, 5.49; Cl, 41.71. Found: C, 28.12; H, 6.27; N, 5.53; Cl, 41.48%. IR
m
= 3223m-br, 3160m, 3127m (m .
N–H) cmꢁ1 1H NMR (CDCl3):
d = 6.04 (br, 3H, NH); 2.89 (br, 2H, CH2); 1.63 (br, 2H, CH2); 0.95
(solid state):
m = 3088s, 2981m, 1468vs, 1456s, 1415m, 1390s,
(br, 3H, CH3) ppm. 13C{1H} NMR (CDCl3): d = 41.9 (CH2); 20.1
1360w, 1287w, 1157m, 1062w, 1012s, 939s, 839vs, 804vs,
(CH2); 10.1 (CH3) ppm. 93Nb NMR (CDCl3): d = ꢁ0.1 (
Dm
½ = 1ꢂ102 Hz)
729m cmꢁ1 1H NMR (CD3CN): d = 9.0 (br, 1H, NH); 3.13 (m, 6H,
.
ppm.
CH2); 1.29 (t, 3JHH = 7.15 Hz, 9H, CH3) ppm. 13C{1H} NMR (CD3CN):
d = 46.6 (CH2); 8.3 (CH3) ppm. 93Nb NMR (CD3CN): d = ꢁ495
[NHi2Pr2][NbCl6], 2c: Grey solid, from NbCl5 (290 mg, 1.07 mmol)
and NHiPr2 (0.150 mL, 1.07 mmol). Yield 127 mg (29%). Anal. Calc.
for C6H16Cl6NNb: C, 17.67; H, 3.95; N, 3.43; Cl, 52.16. Found: C,
(D
m
½ = 1.1ꢂ103 Hz) ppm. Magnetic measurement: vcMorr = 6.68
ꢃ 10ꢁ4 cgsu,
leff = 1.27 BM.
17.55; H, 4.04; N, 3.38; Cl, 52.27%. IR (solid state):
m
= 3131s,
In a different experiment, NbCl5 (0.35 mmol) and NEt3
3095s (
m
N–H) cmꢁ1 1H NMR (CDCl3): d = 5.70 (br, 2H, NH); 3.75
.
(0.35 mmol) were allowed to react in CH2Cl2 (10 mL). The final
dark-red/brown mixture was dried under vacuo. Subsequent IR
spectrum recorded on the dark-brown residue displayed bands at
1661 (w) and 1608 (w-m) cmꢁ1. Magnetic analysis was as follows:
(m, 2H, CH); 1.58 (m, 12H, CH3) ppm. 93Nb NMR (CDCl3): d = 7.0
(D
m
½ = 2ꢂ103 Hz) ppm.
4.4. Reactivity of NbCl5 with N(CH2Ph)3: synthesis and isolation of
v
M = 3.06 ꢃ 10ꢁ4 cgsu.
[(PhCH2)2N@CHPh][NbCl6], 3, and identification of [NH(CH2Ph)3]+
4.6. X-ray crystallographic studies
The reaction of NbCl5 (320 mg, 1.18 mmol) with N(CH2Ph)3
(341 mg, 1.19 mmol) was carried out with a procedure analogous
to that described for the synthesis of 1/2a. Crystallization from
CH2Cl2/hexane at ꢁ30 °C afforded 3 as yellow crystals. Yield
205 mg (29%). Anal. Calc. for C21H20Cl6NNb: C, 42.60; H, 3.41; N,
Crystal data and collection details for [NbCl4(NEt2)]2, 1,
[NH2Et2][NbCl6], 2a, [(PhCH2)2N@CHPh][NbCl6], 3, [NHEt3][NbCl6],
4, and [NHEt3]2[NbCl6], 5, are reported in Table 6. The diffraction
experiments were carried out on a Bruker APEX II diffractometer