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(1.12 g, 2.22 mmol) in THF (50 ml) and tert-butylisocya-
nide (0.18 g, 2.22 mmol) were subsequently added to this
solid at ꢀ30 ꢁC. The reaction mixture was allowed to warm
to room temperature and stirred for 40 min. Solvent was
then removed by applying reduced pressure and the result-
ing residue washed with Et2O (3 · 30 ml) to yield the title
complex as an orange crystalline solid (1.50 g, 80%). IR
(400 MHz, CD3CN): d 0.16 (s, 18H, SiMe3), 5.18 (4H),
5.79 (2H), 5.87 (2H) (m, C5H4), 6.60 (2H), 7.15 (2H),
7.40 (1H) (m, NPh), 6.83 (4H), 6.99 (8H), 7.26 (8H) (m,
BPh). 13C{1H} NMR (100 MHz, CD3CN): d 0.3 (SiMe3),
112.8, 113.9, 118.0, 119.6, 121.1 (C5H4), 122.7, 126.7,
136.8, 164.5 (BPh), 124.0, 126.8, 129.6, 156.3 (NPh),
259.8 (CO). Anal. Calc. for C47H51BNNbOSi2: C, 70.05;
H, 6.38; N, 1.74. Found C, 69.89; H, 6.34; N, 1.77%.
(Nujol mull): mCN 2215, mNb@N 1232 cmꢀ1 1H NMR
.
(400 MHz, CD3CN): d 0.34 (s, 18H, SiMe3), 1.05 (s, 9H,
NBut), 1.70 (s, 9H, CNBut), 6.11 (2H), 6.17 (2H), 6.20
(2H), 6.59 (2H) (m, C5H4), 6.83 (4H), 6.98 (8H), 7.26
(8H) (m, Ph). 13C{1H} NMR (100 MHz, CD3CN): d 0.1
(SiMe3), 29.5 (CNCMe3), 30.7 (NCMe3), 62.7 (CNCMe3),
72.5 (NCMe3), 107.1, 114.2, 119.7, 122.4, 123.3 (C5H4),
128.0 (CNBut), 126.2, 134.3, 138.3, 164.3 (Ph). Anal. Calc.
for C49H64BN2NbSi2: C, 69.98; H, 7.67; N, 3.33. Found C,
69.67; H, 7.61; N, 3.31%.
4.5. Synthesis of [Nb(@NBut){Me2Si(g5-C5Me4)-
(g5-C5H4)}(CNBut)][BPh4] (4)
The preparation of 4 was carried out in an iden-
tical manner to 1. [Nb(@NBut){Me2Si(g5-C5Me4)(g5-
C5H4)}Cl] (0.45 g, 1.02 mmol), Na (0.023 g, 1.02 mmol),
[Fe(g5-C5H5)2][BPh4] (0.51 g, 1.02 mmol) and tert-butyliso-
cyanide (0.085 g, 1.02 mmol). Yield 0.52 g, 63%. IR (Nujol
1
mull): mCN 2215, mNb@N 1260 cmꢀ1. H NMR (400 MHz,
4.3. Synthesis of [Nb(@NPh)(g5-C5H4SiMe3)2(CNBut)]-
[BPh4] (2)
CD3CN): d 0.54 (3H), 0.79 (3H) (s, SiMe2), 1.02 (s, 9H,
NBut), 1.73 (s, 9H, CNBut), 1.88 (3H), 2.08 (3H), 2.14
(3H), 2.68 (3H) (s, C5Me4), 6.12 (4H), 6.60 (2H), 6.87
(2H) (m, C5H4), 6.83 (4H), 6.97 (8H), 7.25 (8H) (m,
BPh). 13C{1H} NMR (100 MHz, CD3CN): d ꢀ1.8, ꢀ0.7
(SiMe2), 12.6, 13.9, 14.6, 16.7 (C5Me4), 29.9 (CNCMe3),
31.2 (NCMe3), 68.8 (CNCMe3), 71.1 (NCMe3), 105.8,
111.1, 111.3, 119.5, 120.3 (C5H4), 106.7, 125.4, 125.6,
130.9, 135.6 (C5Me4), 128.5 (CNBut), 122.6, 126.5, 136.6,
164.5 (BPh). Anal. Calc. for C49H60BN2NbSi: C, 72.76;
H, 7.48; N, 3.46. Found C, 72.58; H, 7.46; N, 3.49%.
The preparation of 2 was carried out in an identical
manner to 1. [Nb(@NPh)(g5-C5H4SiMe3)2Cl] (0.21 g,
0.43 mmol), Na (0.010 g, 0.43 mmol), [Fe(g5-C5H5)2][BPh4]
(0.22 g, 0.43 mmol) and tert-butylisocyanide (0.035 g,
0.43 mmol). Yield 0.20 g, 54%. IR (Nujol mull): mCN 2216,
1
mNb@N 1246 cmꢀ1. H NMR (400 MHz, CD3CN): d 0.15
(s, 18H, SiMe3), 1.72 (s, 9H, CNBut), 6.29 (2H), 6.35
(2H), 6.50 (2H), 6.69 (2H) (m, C5H4), 6.39 (2H), 6.88
(2H), 7.20 (1H) (m, NPh), 6.83 (4H), 6.98 (8H), 7.26 (8H)
(m, BPh). 13C{1H} NMR (100 MHz, CD3CN): d ꢀ0.1
(SiMe3), 29.6 (CNCMe3), 63.5 (CNCMe3), 113.7, 114.6,
117.8, 119.5, 120.3 (C5H4), 128.1 (CNBut), 122.8, 126.7,
136.8, 162.8 (BPh), 124.4, 126.5, 129.5, 158.0 (NPh). Anal.
Calc. for C51H60BN2NbSi2: C, 71.15; H, 7.02; N, 3.25.
Found C, 70.89; H, 7.10; N, 3.16%.
4.6. Synthesis of [(Nb{Me2Si(g5-C5H4)2}(l-NBut))2] (5)
A solution of [Nb(@NBut){Me2Si(g5-C5H4)2}Cl] (0.40
g, 1.04 mmol) in THF (50 ml) was added, at ꢀ30 ꢁC, to
Na amalgam (0.024 g, 1.04 mmol of Na). The mixture
was initially stirred for 10 min at ꢀ 30 ꢁC and then allowed
to warm to room temperature whilst stirring for a further
10 min. THF was removed under reduced pressure and
hexane (50 ml) added. The resulting suspension was cooled
to ꢀ40 ꢁC and then filtered. Solvent was removed, from the
filtrate, in vacuo, to yield the title complex as a brown crys-
talline solid (0.29 g, 81%). IR (Nujol mull): mNb–N
4.4. Synthesis of [Nb(@NPh)(g5-C5H4SiMe3)2(CO)]-
[BPh4] (3)
A solution of [Nb(@NPh)(g5-C5H4SiMe3)2Cl] (0.21 g,
0.42 mmol) in THF (50 ml) was added, at 0 ꢁC, to Na
amalgam (0.010 g, 0.43 mmol of Na). The mixture was
allowed to warm to room temperature and stirred for
30 min. THF was removed under reduced pressure and
hexane (50 ml) added. The resulting suspension was filtered
and solvent was removed, from the filtrate, in vacuo to
yield a red oily solid. A solution of [Fe(g5-C5H5)2][BPh4]
(0.22 g, 0.43 mmol) in THF (50 ml) was subsequently
added to this solid at ꢀ30 ꢁC. Nitrogen pressure was
reduced by applying vacuum and replaced by CO gas.
The reaction mixture was allowed to warm to room tem-
perature and stirred for 40 min. Solvent and excess CO
were then removed by applying reduced pressure and the
resulting residue washed with Et2O (3 · 30 ml) to yield
the title complex as a pink crystalline solid (0.22 g, 61%).
1
1095 cmꢀ1. H NMR (400 MHz, C6D6): d 0.49 (s, 12H,
SiMe2), 1.44 (s, 18H, NBut), 5.04 (8H), 5.79 (8H) (m,
C5H4). 13C{1H} NMR (100 MHz, C6D6): d ꢀ3.4 (SiMe2),
35.8 (NCMe3), 72.9 (NCMe3), 100.0, 109.8, 116.2 (C5H4).
Anal. Calc. for C32H46N2Nb2Si2: C, 54.85; H, 6.62; N,
4.00. Found C, 54.51; H, 6.57; N, 4.05%.
4.7. Synthesis of [Nb(@NBut){Me2Si(g5-C5H4)2}H] (6)
A
solution of [Nb(@NBut){Me2Si(g5-C5H4)2}Cl]
(0.47 g, 1.22 mmol) in THF (50 ml) was added, at 25 ꢁC,
to Na amalgam (0.028 g, 1.22 mmol of Na). The mixture
was stirred for 12 h. THF was removed under reduced
pressure and hexane (50 ml) added. The resulting suspen-
sion was filtered. The filtrate was cooled to ꢀ40 ꢁC to yield
1
IR (Nujol mull): mCO 1932, mNb@N 1239 cmꢀ1. H NMR
Garcés, Andrés
