Tris(cyclopentadienyl)zirconium Cations
Organometallics, Vol. 16, No. 4, 1997 535
via ψ-scan data (0.925 e C e 0.999), Z ) 2, tetragonal, space
group I4h (No. 82), λ ) 0.710 73 Å, ω/2θ scans, 818 reflections
collected (+h,+k,(l), [(sin θ)/λ]max ) 0.62 Å-1, 716 independent
and 647 observed reflections [I e 2σ(I)], 48 refined parameter,
R ) 0.067, wR2 ) 0.170, maximum residual electron density
0.55 (-0.61) e Å-3; refinement, Zr anisotropic, Cp ring as rigid
group, restraints on anisotropic thermal parameters for all
carbon atoms (similar Uij of neighbouring atoms, quasi-
isotropic behavior), occupancy(C1-C5) ) 0.75, occupancy(C6)
) 0.25, hydrogens calculated and riding.
243 Hz), 136.2 (1J CF ) 245 Hz) and 128.7 (br s; o-, p-, m-, and
ipso-C of B(C6F5)3-), 137.2 (Ph-CN), 136.8, 133.0, 130.1, 107.5
(p-, o-, m-, and ipso-C of Ph), 114.8 (Cp), 10.0 (br, B-CH3). IR
(KBr): ν˜ ) 3130, 2975, 2926, 2251, 1642, 1511, 1266, 1088,
951, 810 cm-1
.
[(ter t-Bu t yl isocya n id e)t r is(η5-cyclop en t a d ien yl)zir -
con iu m ] Meth yltr is(p en ta flu or op h en yl)bor a te (12). As
described above, the [Cp3Zr]+[CH3B(C6F5)3]- salt 9 was gener-
ated by treatment of 100 mg (0.33 mmol) of 7 with 175 mg
(0.34 mmol) of B(C6F5)3 in 15 mL of dichloromethane. At -78
°C 0.19 mL (137 mg, 1.65 mmol) of tert-butyl isocyanide was
added, the mixture allowed to warm to room temperature, and
then the solution concentrated to half of its volume in vacuo.
Pentane (20 mL) was added and the precipitated product 12
collected by filtration, washed with a small amount of pentane,
and dried in vacuo to yield 215 mg (73%) of 12, mp 113 °C.
Anal. Calcd for C39H27BNF15Zr (896.7): C, 52.24; H, 3.04; N,
1.56. Found: C, 51.37; H, 3.14; N, 1.62. 1H NMR (dichloro-
methane-d2): δ 5.91 (s, 15H, Cp), 1.77 (br s, 9H, C(CH3)3), 0.51
(br s, 3H, B-CH3). 13C NMR (dichloromethane-d2): δ 148.0
(1J CF ) 241 Hz), 137.4 (1J CF ) 243 Hz), 136.3 (1J CF ) 245 Hz),
and 128.6 (br s, o-, p-, m-, and ipso-C of RB(C6F5)3-), 145.4 (br
s; RNC), 111.7 (Cp), 61.3 and 29.9 (CMe3), 10.0 (br s, B-CH3).
IR (KBr): ν˜ ) 3134, 2990, 2961, 2209, 1641, 1511, 1456,1266,
Gen er a t ion of Tr is(η5-cyclop en t a d ien yl)zir con iu m
Meth yltr is(p en ta flu or op h en yl)bor a te (9). In a 5 mm
NMR tube was reacted 16.0 mg (31.3 µmol) of B(C6F5)3 with
9.0 mg (29.8 µmol) of Cp3ZrCH3 (7) in 0.6 mL of benzene-d6
or dichloromethane-d2, respectively. A pale yellow solution
of 9 was obtained. At ambient temperature the [Cp3Zr]+
[CH3B(C6F5)3]- salt is decomposed after several hours. At -30
°C in dichloromethane-d2 it can be kept without decomposition
for several days. The salt 9 could not be isolated as yet. It
was characterized spectroscopically. 1H NMR (benzene-d6): δ
5.31 (s, 15H, Cp), 0.12 (br s, 3H, CH3-B). 1H NMR (dichloro-
methane-d2): δ 6.30 (s, 15H, Cp), 0.48 (br s, 3H, CH3-B). 13C
NMR (dichloromethane-d2): δ 148.7 (1J CF ) 240 Hz), 140.0
(1J CF ) 234 Hz), 136.9 (1J CH ) 245 Hz) and 129.0 (br, s; o-, p-,
m-, and ipso-C of MeB(C6F5)3-), 117.6 (Cp), 8.9 (B-CH3).
[T r is (η5 -c y c lo p e n t a d ie n y l)(t e t r a h y d r o fu r a n )zir -
con iu m ] Tetr a p h en ylbor a te (8). Tris(η5-cyclopentadienyl)-
methylzirconium (6) (457 mg, 1.52 mmol) was treated with
950 mg (2.15 mmol) of N,N-dimethylanilinium tetraphenylbo-
rate at -78 °C in 25 mL of THF. The reaction mixture was
stirred for 1 h at -78 °C and then for 4 h at 0 °C. After ca. 2
h the product began to precipitate. It was collected by filtration
and washed with pentane to give 325 mg (32%) of 8, mp 52 °C
(dec). 1H NMR (THF-d8): δ 6.24 (s, 15H, Cp), 3.62 (m, 4H)
and 1.77 (m, 4H, THF); BPh4 anion, δ 7.40-7.20 (m, 8H),
7.00-6.80 (m, 8H), 6.80-6.65 (m, 4H). IR (KBr): ν˜ ) 3119,
3069, 3051, 2980, 2851, 1591, 1479, 1431, 1240, 1015, 885, 802,
1081, 957, 820 cm-1
. Single crystals were obtained from
dichloromethane at -30 °C. X-ray crystal structure analysis
of 12: formula C39H27BF15NZr, M ) 896.65, 0.7 × 0.5 × 0.4
mm, a ) 13.330(1) Å, b ) 13.152(1) Å, c ) 21.062(1) Å, â )
100.54(1)°, V ) 3630.2(4) Å3, Fcalc ) 1.641 g cm-3, µ ) 4.11
cm-1, empirical absorption correction via ψ-scan data (0.980
e C e 0.999), Z ) 4, monoclinic, space group P21/n (No. 14), λ
) 0.710 73 Å, ω/2θ scans, 7575 reflections collected ((h,-k,+l),
[(sin θ)/λ]max ) 0.62 Å-1, 7372 independent and 5943 observed
reflections [I e 2σ(I)], 518 refined parameter, R ) 0.039, wR2
) 0.124, maximum residual electron density 0.57 (-0.79) e
Å-3, hydrogens calculated and riding.
[(Ca r bon yl)tr is(η5-cyclop en ta d ien yl)zir con iu m ] Meth -
yltr is(p en ta flu or op h en yl)bor a te (13). As described above,
the salt 9 was generated by treatment of 100 mg (0.33 mmol)
of 7 with 175 mg (0.34 mmol) of B(C6F5)3 in 20 mL of
dichloromethane in a 100 mL Schlenk flask. The argon
atmosphere was removed from the flask in vacuo and replaced
with carbon monoxide. The mixture was stirred under a
constant (1 bar) CO pressure for 20 min at ambient temper-
ature. The reaction mixture was concentrated to half its
volume in vacuo and then kept at -30 °C for several days to
yield a number of yellow single crystals of 13 that were
collected by filtration and dried in vacuo, yield 106 mg (38%).
Anal. Calcd for C35H18BOF15Zr (842.4): C, 49.95; H, 2.16.
Found: C, 49.24; H, 2.18. 1H NMR (dichloromethane-d2): δ
6.05 (s, 15H, Cp), 0.52 (br s, 3H, B-CH3). 13C NMR (dichloro-
methane-d2): δ 206.9 (CO), 112.7 (Cp). IR (KBr): ν˜ ) 3118,
2934, 2855, 2150, 1650, 1518, 1459, 1274, 1090, 959, 827, 741
735 cm-1
.
[(Ace t on it r ile )t r is(η5-cyclop e n t a d ie n yl)zir con iu m ]
Meth yltr is(p en ta flu or op h en yl)bor a te (10). A Schlenk
flask was charged with Cp3ZrCH3 (7) (100 mg, 0.33 mmol) and
B(C6F5)3 (175 mg, 0.34 mmol) and then cooled to -78 °C. At
that temperature 15 mL of cold (-78 °C) dichloromethane was
added. The mixture was then slowly allowed to warm with
stirring until a clear orange colored solution was obtained. The
solution was then cooled again to -78 °C, and 0.09 mL (68
mg, 1.66 mmol) of acetonitrile was added dropwise. The
resulting pale yellow solution was allowed to warm to room
temperature and then concentrated to ca. half of its original
volume in vacuo. Addition of pentane (15 mL) precipitated
the product 10, which was collected by filtration, washed with
pentane, and dried in vacuo (yield 195 mg, 69%), mp 109 °C.
1H NMR (10:1 dichloromethane-d2/THF-d8): δ 6.08 (s, 15H,
Cp), 2.62 (br s, 3H, CH3CN), 0.48 (br s, 3H, CH3-B). IR
(KBr): ν˜ ) 3138, 2985, 2938, 2907, 2321, 2295, 1642, 1513,
cm-1
. Single crystals were obtained from dichloromethane;
they contained one molecule of CH2Cl2 per 13. X-ray crystal
structure analysis of 13: formula C36H20BCl2F15OZr, M )
926.45, 0.5 × 0.4 × 0.2 mm, a ) 11.189(1) Å, b ) 11.549(1) Å,
c ) 15.191(1) Å, R ) 108.28(1)°, â ) 105.16(1)°, γ ) 100.29-
1457, 1266, 1086, 936, 845, 819, 736 cm-1
.
[(Be n zon it r ile )t r is(η5-cyclop e n t a d ie n yl)zir con iu m ]
Meth yltr is(p en ta flu or op h en yl)bor a te (11). A solid mix-
ture of Cp3ZrCH3 (7) (100 mg, 0.33 mmol) and B(C6F5)3 (175
mg, 0.34 mmol) was cooled to -78 °C. Then 15 mL of cold
(-78 °C) dichloromethane was added and the mixture cleared
at a slightly elevated temperature. Benzonitrile (170 mg, 1.65
mmol) was then added at -78 °C. The mixture was warmed
to room temperature during 30 min, 50% of the solvent
removed in vacuo, and 20 mL of pentane added. The product
11 was collected by filtration, washed with a small amount of
pentane, and dried in vacuo to yield 184 mg (61%) of 11, mp
139 °C. Anal. Calcd for C41H23BNF15Zr (916.6): C, 53.72; H,
2.53. Found: C, 53.91; H, 2.95. 1H NMR (dichloromethane-
d2): δ 7.92 (m, 2H), 7.90 (m, 1H), and 7.69 (m, 2H, o-, p-, m-H
of Ph), 6.13 (s, 15H, Cp), 0.47 (br s, 3H, CH3-B). 13C NMR
(1)°, V ) 1724.8(2) Å3, Fcalc ) 1.784 g cm-3, µ ) 5.87 cm-1
,
empirical absorption correction via ψ-scan data (0.946 e C e
0.999), Z ) 2, triclinic, space group P1h (No. 2), λ ) 0.710 73 Å,
ω/2θ scans, 7381 reflections collected (-h,(k,(l), [(sin θ)/λ] )
0.62 Å-1, 7005 independent and 5940 observed reflections [I
e 2σ(I)], 506 refined parameters, R ) 0.069, wR2 ) 0.234,
maximum residual electron density 1.49 (-1.52) e Å-3, hydro-
gens calculated and riding.
Eth en e P olym er iza tion Exp er im en ts. (A) In a Schlenk
flask was combined 50 mg (0.17 mmol) of Cp3ZrCH3 (7)
with 50 mL of a 10% methylalumoxane solution in toluene
(4.35 g, 93.5 mmol of MAO). The flask was evacuated and
then filled with ethene (1.3 bar) and kept under a constant
ethene pressure for 2 h. After 10 min polymer began to
(dichloromethane-d2): δ 148.3 (1J CF ) 240 Hz), 137.4 (1J CF
)