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J(H,H)=7.5 Hz, 1H; ArH), 7.20–7.26 (t, J(H,H)=7.5 Hz, 1H; ArH),
7.33–7.39 (t, J(H,H)=7.5 Hz, 1H; ArH), 7.51–7.57 (t, J(H,H)=7.5 Hz,
1H; ArH), 7.72–7.75 (d, J(H,H)=7.5 Hz, 1H; ArH), 7.93–7.96 ppm (d,
J(H,H)=7.5 Hz, 1H; ArH); 13C NMR (C6D6, 250 MHz): d=0.46, 10.3,
15.4, 30.1, 36.3, 46.9, 50.1, 105.7, 108.5, 121.0, 125.4, 129.3, 130.0,
137.9, 139.5, 156.2, 157.5 ppm.
Complex 7b: A solution of n-butyllithium (1.6m in hexanes,
1.7 mL, 2.8 mmol) was added to a solution of 6b (0.6 g, 1.1 mmol)
in pentane (15 mL) at À378C. The reaction mixture was warmed to
room temperature and was stirred for 3 h. The resulting precipitate
was collected on a frit, washed with cold pentane, and dried under
vacuum to give a pure Li salt of 6b (0.57 g, 73%) , which was used
without any further analysis.
Ligand 6b: n-Butyllithium (1.6m in hexanes, 2 mL, 3.1 mmol) was
added to a solution of 1b (1 g, 3 mmol) in diethyl ether at À378C.
The pale yellow solution was allowed to warm to room tempera-
ture and was then stirred for another 1 h. The precipitate was col-
lected by filtration, washed with cold diethyl ether/pentane (1:10,
v/v), and dried under vacuum to give a pure yellow Li salt of 1b
(1.1 g, 92%) , which was used without further analysis.
The Li salt of 6b (0.57 g, 0.8 mmol) was dissolved in tetrahydrofur-
an (10 mL) and added dropwise to a solution of ZrCl4·2thf (0.31 g,
0.8 mmol) in tetrahydrofuran (20 mL) at À378C and the resulting
reaction mixture was allowed to stir at room temperature for 6 h.
After removal of the solvent, toluene was added and the mixture
was stirred for half an hour. It was then filtered through Celite and
the filtrate was concentrated under vacuum. The obtained oily
product was recrystallized from dichloromethane/pentane at
À378C to give colorless crystals. Yield: 0.2 g, 31%. 1H NMR
Compound 5 (0.66 g, 2.7 mmol) was added to a suspension of the
lithium salt of 1b (1.1 g, 2.7 mmol) in diethyl ether at À378C. The
solution was allowed to warm to room temperature and was
stirred for 4 h. Afterwards, the solution was filtered over Celite and
was washed with diethyl ether. The volatiles were removed under
vacuum and the crude product was recrystallized from diethyl
3
(400.13 MHz, CD2Cl2): d=0.68 (s, 3H), 1.16 (t, J(H,H)=7.0 Hz, 3H),
1.56 (s, 6H), 1.82 (d, 3J(H,H)=3.0 Hz, 6H), 1.97 (s, 3H), 3.44 (q,
3
3
3J(H,H)=7.0 Hz, 2H), 6.72 (d, J(H,H)=8.4 Hz, 1H), 7.19 (t, J(H,H)=
7.5 Hz, 1H), 7.26 (t, 3J(H,H)=7.3 Hz, 1H), 7.38 (d, 3J(H,H)=7.5 Hz,
1H), 7.42–7.45 (m, 6H), 7.61–7.68 (m, 2H), 7.93–7.98 ppm (m, 5H);
13C NMR (100.62 MHz, CD2Cl2): d=3.6, 15.7, 31.0, 36.6, 46.4, 61.0,
66.3, 107.3, 113.7, 122.0, 126.9, 128.9, 131.2, 132.0, 132.1, 136.0,
136.4, 142.6, 157.4, 159.7 ppm; elemental analysis calcd (%) for
1
ether/pentane. Yield 1.2 g, 86%. H NMR (400.13 MHz, CD2Cl2): d=
À0.03 (s, 3H), 0.91 (s, 1H), 1.15 (t, 3J(H,H)=7.0 Hz, 6H), 1.37 (d,
3J(H,H)=2.5 Hz, 6H), 1.44 (d, 3J(H,H)=11.2 Hz, 3H), 1.53 (d,
3J(H,H)=12.1 Hz, 3H), 1.86 (s, 3H), 3.43 (q, 3J(H,H)=7.0 Hz, 4H),
5.19 (s, 1H), 6.99 (d, 3J(H,H)=8.5 Hz, 1H), 7.10 (m, 2H), 7.17 (m,
4H), 7.28 (m, 6H), 7.34 (d, 3J(H,H)=7.5 Hz, 1H), 7.48 (d, 3J(H,H)=
6.8 Hz, 1H), 7.77 ppm (m, 2H); 13C NMR (100.62 MHz, CD2Cl2): d=
0.3, 15.7, 30.5, 36.6, 46.9, 50.4, 66.2, 106.3, 110.9, 121.5, 126.1,
126.2, 127.9, 129.6, 130.8, 133.7, 137.4, 141.1, 156.7, 157.2 ppm;
FTIR (ATR): n˜ =3120 (s), 3080 (w), 2905 (s), 1626 (s), 1569 (s), 1493
(s), 1454 (m), 1382 (m), 1305 (m), 1261 (m), 1171 (s), 1140 (s), 1097
(m), 1034 (s), 1005 (m), 877 (s), 836 (s), 760 (s), 731 (s), 703 cmÀ1 (s);
ESI-MS: m/z calcd (%) for C35H40BN3Si: 541.61; found: 541.32.
C35H38BCl2N3SiZr·0.5C4H10O·0.5CH2Cl2:
found: C 57.84, H 5.84, N 5.36.
C 57.65, H 5.69, N 5.38;
Complex 8: A solution of nBuLi (1.6m in hexanes, 0.73 mL,
1.14 mmol) was added to a solution of 3 (200 mg, 0.544 mmol) in
n-pentane (15 mL) at À378C. A large amount of white precipitate
formed during the addition. The reaction mixture was warmed to
room temperature and was stirred for 3 h. The resulting precipitate
was collected on a frit, washed with cold n-pentane (10 mL), and
dried under vacuum to give the pure Li salt of 3 (160 mg), which
was used without any further analysis.
Complex 7a: A solution of nBuLi (1.6m in hexanes, 1.28 mL,
2.0 mmol) was added to a solution of 6a (420 mg, 0.94 mmol) in n-
pentane (40 mL) at À378C. A large amount of white precipitate
formed during the addition. The reaction mixture was warmed to
room temperature and was stirred for 12 h. The resulting precipi-
tate was collected on a frit, washed with cold n-pentane (10 mL),
and dried under vacuum to give the pure Li salt of 6a (350 mg),
which was used without any analysis.
The Li salt of 3 (240 mg, 0.632 mmol) was dissolved in toluene
(15 mL), this solution was added to a solution of HfCl4 (202 mg,
0.632 mmol) in toluene (20 mL) at À378C and the resulting reac-
tion mixture was stirred at room temperature for 9 h. Then it was
filtered through Celite and all volatile materials were removed
under reduced pressure. n-Pentane was added and the solution
was stored in a glovebox freezer for 24 h to precipitate 8 (200 mg,
51%) as a white solid. 1H NMR (C6D6, 250 MHz): d=0.54 (s, 3H;
Si(CH3)2), 0.74–0.83 (m, 9H; Si(CH3)2, ÀB(CH2CH3)2), 1.26–1.58 (m, 4H;
B(CH2CH3)2), 1.64 (s, 9H; t-butyl), 6.73–6.76 (dd, J(H,H)=0.75 Hz,
1H; ArH), 6.94–6.98 (dd, J(H,H)=0.5 Hz, 1H; ArH), 7.19–7.25 (t,
J(H,H)=7.5 Hz, 1H; ArH), 7.31–7.38 (ddd, J(H,H)=1 Hz, 1H; ArH),
7.50–7.56 (ddd, J(H,H)=0.75 Hz, 1H; ArH), 7.68–7.72 (d, J(H,H)=
7.75 Hz, 1H; ArH), 7.76–7.78 ppm (d, J(H,H)=7.25 Hz, 1H; ArH);
13C NMR (C6D6, 250 MHz): d=5.4, 5.91, 11.3, 12.0, 12.5, 19.7, 35.9,
56.9, 107.7, 117.0, 121.3, 125.8, 129.4, 130.0, 138.1, 139.3, 158.4,
161.6 ppm; elemental analysis calcd (%) for C42H64B2HfN6Si2: C
55.48, H 7.09, N 9.24; found: C 55.45, H 7.20, N 9.19.
The Li salt of 6a (350 mg, 0.76 mmol) was dissolved in toluene
(20 mL) and added to a solution of ZrCl4·2thf (0.29 g, 0.76 mmol) in
toluene (30 mL) at À378C and the resulting reaction mixture was
allowed to stir at room temperature for 16 h. Then the reaction
mixture was filtered through Celite and all volatiles were removed
under reduced pressure. The crude product was dissolved in n-
pentane (10 mL) from which 7a (280 mg, 45%) crystallized as an
off-white solid. 1H NMR (C6D6, 250 MHz): d=0.62 (s, 3H; Si(CH3)2),
0.78–083 (t, J(H,H)=5 Hz, 6H; B(CH2CH3)2), 0.89 (s, 3H; Si(CH3)2), 1.1
(br, thf), 1.3–1.46 (m, 4H; B(CH2CH3)2), 1.67–1.91 (m, 6H; AdÀCH2),
2.28 (s, 3H; AdÀCH), 2.37 (s, 6H; AdÀCH2), 4.30 (br, thf), 6.7–6.8 (d,
J(H,H)=10 Hz, 1H; ArH), 6.97–7.00 (d, J(H,H)=7.5 Hz, 1H; ArH),
7.20–7.23 (d, J(H,H)=7.5 Hz, 1H; ArH), 7.32–7.39 (ddd, J(H,H)=
2.5 Hz, 1H; ArH), 7.51–7.58 (ddd, J(H,H)=2.5 Hz, 1H; ArH), 7.70–
7.73 (d, J(H,H)=7.5 Hz, 1H; ArH), 7.76–7.79 ppm (d, J(H,H)=7.5 Hz,
1H; ArH); 13C NMR (C6D6, 250 MHz): d=5.7, 6.3, 11.2, 11.8, 20.5,
25.1 (coordinated thf), 30.7, 36.6, 48.0, 58.9, 78.6 (coordinated thf),
107.3, 115.9, 121.1, 125.6, 129.1, 129.7, 138.0, 139.1, 158.2,
160.9 ppm; elemental analysis calcd (%) for C31H46BCl2N3OSiZr: C
54.94, H 6.84, N 6.20; found: C 55.39, H 7.39, N 5.88.
Complex 9: A solution of nBuLi (1.6m in hexanes, 0.73 mL,
1.14 mmol) was added to a solution of 6a (200 mg, 0.544 mmol) in
n-pentane (15 mL) at À378C. A large amount of white precipitate
formed during the addition. The reaction mixture was warmed to
room temperature and was stirred for 3 h. The resulting precipitate
was collected on a frit, washed with cold n-pentane (10 mL), and
dried under vacuum to give the pure Li salt of 6a (160 mg), which
was used without any further analysis. The Li salt of 6a (400 mg,
0.87 mmol) was dissolved in toluene (20 mL) and added to a solu-
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ChemPlusChem 2014, 79, 151 – 162 160
Narayana, Gurram Venkata
