Tris(η⁵-cyclo­penta­dien­yl)hafnium(III)

In the crystal structure of the title compound, [Hf(C₅H₅)₃], three cyclo­penta­dienyl ligands surround the Hf^III atom in a trigonal–planar geometry. The mol­ecule lies on a sixfold inversion axis.

Related literature

Isotypic (η⁵-C₅H₅)₃Zr was described by Lukens & Andersen (1995). For (η⁵-C₅H₅)₃M, M = Y: see Adam et al. (1991); M = Nd: see Eggers et al. (1992a); M = Sm: see Wong et al. (1969), Bel'skii et al. (1991), Eggers et al. (1992b); M = Er, Tm: see Eggers et al. (1986); M = Yb: see Eggers et al. (1987); M = Ce, Dy, Ho: see Baisch et al. (2006). Unit-cell dimensions of (η⁵-C₅H₅)₃M (M = Pr, Pm, Sm, Gd, Tb, Tm, Cm, Bk, Cf) were determined by Laubereau & Burns (1970a,b).

Experimental

Crystal data

• [Hf(C₅H₅)₃]

• M_r = 373.76

• Hexagonal, P 6₃ /m

• a = 7.9772 (4) Å

• c = 10.2975 (6) Å

• V = 567.50 (5) ų

• Z = 2

• Mo Kα radiation

• μ = 9.16 mm⁻¹

• T = 150 K

• 0.30 × 0.20 × 0.15 mm

Data collection

• Stoe IPDS II diffractometer

• Absorption correction: numerical (X-SHAPE and X-RED32; Stoe & Cie, 2005) T_min = 0.150, T_max = 0.346

• 7314 measured reflections

• 362 independent reflections

• 333 reflections with I > 2σ(I)

• R_int = 0.097

Refinement

• R[F² > 2σ(F²)] = 0.034

• wR(F²) = 0.076

• S = 1.22

• 362 reflections

• 27 parameters

• H-atom parameters constrained

• Δρ_max = 0.95 e Å⁻³

• Δρ_min = −3.40 e Å⁻³

Data collection: X-AREA (Stoe & Cie, 2005); cell refinement: X-AREA; data reduction: X-AREA; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97.

Supporting information

S1. Comment

In the reaction of (η⁵-C₅H₅)₂Hf[—C(SiMe₃)═C(C≡CSiMe₃)— C(SiMe₃)═C(C≡CSiMe₃)—] with (i-Bu)₂AlH single crystals of the title compound as lone product in very low yield were isolated. Isostructural compounds are known for M = Zr (Lukens et al., 1995), M = Y (Adam et al., 1991), M = Nd (Eggers et al., 1992a), M = Sm (Wong et al., 1969; Bel'skii et al., 1991; Eggers et al., 1992b), M = Er, Tm (Eggers et al., 1986), M = Yb (Eggers et al., 1987), M = Ce, Dy, Ho (Baisch et al., 2006). (η⁵-C₅H₅)₃Hf crystallizes in the hexagonal space group P6₃/m with unit-cell dimensions isomorphous with the Zr analogue (Lukens et al., 1995). The Hf(III) center is surrounded by three η⁵-coordinated cyclopentadienyl ligands in a trigonal planar geometry. The Hf—C distances are with 2.547 (6) and 2.575 (6) Å in the expected range.

Related literature

Isotypic (η⁵-C₅H₅)₃Zr was described by Lukens et al. (1995). For (η⁵-C₅H₅)₃M, M = Y: see Adam et al. (1991); M = Nd: see Eggers et al. (1992a); M = Sm: see Wong et al. (1969), Bel'skii et al. (1991), Eggers et al. (1992b); M = Er, Tm: see Eggers et al. (1986); M = Yb: see Eggers et al. (1987); M = Ce, Dy, Ho: see Baisch et al. (2006). Unit-cell dimensions of (η⁵-C₅H₅)₃M (M = Pr, Pm, Sm, Gd, Tb, Tm, Cm, Bk, Cf) were determined by Laubereau & Burns (1970a,b).

S2. Experimental

An amount of 0.460 g (0.66 mmol) of the five membered metallacycle (η⁵-C₅H₅)₂Hf[—C(SiMe₃)═C(C≡CSiMe₃)—C(SiMe₃)═ C(C≡CSiMe₃)—] was dissolved in 20 ml of n-hexane under Ar, and 2.6 ml (2.6 mmol) of a 1.0 M solution of (i-Bu)₂AlH in cyclohexane was added to the obtained yellow solution. After one day the obtained red-brown solution was filtered and allowed to stand in argon atmosphere at -40 °C. After 6 month the light-yellow crystals had formed which were separated from the mother liquor by decanting, washed with cooled n-hexane, and dried in vacuum to give (η⁵-C₅H₅)₃Hf. Yield 9.3% (23 mg). M.p. 261–263 °C (dec. under Ar). MS (70 eV, m/z): 375 (M⁺), 310 (M⁺-C₅H₅).

S3. Refinement

H atoms were placed in idealized positions with d(C—H) = 0.95 Å and refined using a riding model with U_iso(H) fixed at 1.2 U_eq(C).

A numerical absorption correction was performed. Hence the largest peak of 0.95 (1.57 Å from Hf1) and the deepest hole of -3.40 e Å^-3 (0.98 Å from Hf1) in the final difference Fourier map were obtained.

Computing details

Data collection: X-AREA (Stoe & Cie, 2005); cell refinement: X-AREA (Stoe & Cie, 2005); data reduction: X-AREA (Stoe & Cie, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

Fig. 1. The molecular structure of the title compound showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level.

Tris(η⁵-cyclopentadienyl)hafnium(III)

Crystal data

[Hf(C5H5)3]	Dx = 2.187 Mg m^−3
Mr = 373.76	Mo Kα radiation, λ = 0.71073 Å
Hexagonal, P63/m	Cell parameters from 4609 reflections
Hall symbol: -P 6c	θ = 1.9–28.4°
a = 7.9772 (4) Å	µ = 9.16 mm^−1
c = 10.2975 (6) Å	T = 150 K
V = 567.50 (5) Å^3	Prism, yellow
Z = 2	0.30 × 0.20 × 0.15 mm
F(000) = 354

Data collection

Stoe IPDS II diffractometer	362 independent reflections
Radiation source: fine-focus sealed tube	333 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.097
ω scans	θmax = 25.0°, θmin = 3.0°
Absorption correction: numerical (X-SHAPE and X-RED32; Stoe & Cie, 2005)	h = −9→9
Tmin = 0.150, Tmax = 0.346	k = −9→9
7314 measured reflections	l = −12→12

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.034	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.076	H-atom parameters constrained
S = 1.22	w = 1/[σ^2(Fo^2) + (0.0163P)^2 + 5.6136P] where P = (Fo^2 + 2Fc^2)/3
362 reflections	(Δ/σ)max < 0.001
27 parameters	Δρmax = 0.95 e Å^−3
0 restraints	Δρmin = −3.40 e Å^−3

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Hf1	0.3333	0.6667	0.2500	0.0342 (3)
C1	0.4331 (9)	0.4179 (9)	0.1824 (6)	0.0236 (13)
H1	0.5434	0.4592	0.1283	0.028*
C2	0.2408 (10)	0.3460 (10)	0.1393 (7)	0.0300 (15)
H2	0.1992	0.3347	0.0517	0.036*
C3	0.1229 (14)	0.2944 (13)	0.2500	0.026 (2)
H3	−0.0143	0.2344	0.2500	0.032*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Hf1	0.0126 (3)	0.0126 (3)	0.0772 (6)	0.00632 (15)	0.000	0.000
C1	0.022 (3)	0.019 (3)	0.031 (3)	0.011 (3)	0.003 (3)	−0.002 (3)
C2	0.024 (3)	0.027 (4)	0.035 (4)	0.010 (3)	−0.004 (3)	−0.001 (3)
C3	0.017 (4)	0.014 (4)	0.048 (6)	0.008 (4)	0.000	0.000

Geometric parameters (Å, º)

Hf1—C2^i	2.549 (7)	Hf1—C1	2.576 (6)
Hf1—C2^ii	2.549 (7)	Hf1—C1^ii	2.576 (6)
Hf1—C2^iii	2.549 (7)	C1—C1^ii	1.392 (12)
Hf1—C2^iv	2.549 (7)	C1—C2	1.414 (9)
Hf1—C2	2.549 (7)	C1—H1	0.9500
Hf1—C2^v	2.549 (7)	C2—C3	1.402 (9)
Hf1—C1^i	2.576 (6)	C2—H2	0.9500
Hf1—C1^iii	2.576 (6)	C3—C2^ii	1.402 (9)
Hf1—C1^iv	2.576 (6)	C3—H3	0.9500
Hf1—C1^v	2.576 (6)
C2^i—Hf1—C2^ii	101.55 (19)	C1^i—Hf1—C1^v	122.45 (4)
C2^i—Hf1—C2^iii	53.1 (3)	C1^iii—Hf1—C1^v	112.98 (12)
C2^ii—Hf1—C2^iii	126.86 (8)	C1^iv—Hf1—C1^v	31.4 (3)
C2^i—Hf1—C2^iv	101.55 (19)	C2^i—Hf1—C1	152.1 (2)
C2^ii—Hf1—C2^iv	101.55 (19)	C2^ii—Hf1—C1	52.7 (2)
C2^iii—Hf1—C2^iv	126.86 (8)	C2^iii—Hf1—C1	130.0 (2)
C2^i—Hf1—C2	126.86 (8)	C2^iv—Hf1—C1	94.8 (2)
C2^ii—Hf1—C2	53.1 (3)	C2—Hf1—C1	32.0 (2)
C2^iii—Hf1—C2	101.55 (19)	C2^v—Hf1—C1	81.0 (2)
C2^iv—Hf1—C2	126.86 (8)	C1^i—Hf1—C1	122.45 (4)
C2^i—Hf1—C2^v	126.86 (8)	C1^iii—Hf1—C1	112.98 (12)
C2^ii—Hf1—C2^v	126.86 (8)	C1^iv—Hf1—C1	122.45 (4)
C2^iii—Hf1—C2^v	101.55 (19)	C1^v—Hf1—C1	112.98 (12)
C2^iv—Hf1—C2^v	53.1 (3)	C2^i—Hf1—C1^ii	130.0 (2)
C2—Hf1—C2^v	101.55 (19)	C2^ii—Hf1—C1^ii	32.0 (2)
C2^i—Hf1—C1^i	32.0 (2)	C2^iii—Hf1—C1^ii	152.1 (2)
C2^ii—Hf1—C1^i	81.0 (2)	C2^iv—Hf1—C1^ii	81.0 (2)
C2^iii—Hf1—C1^i	52.7 (2)	C2—Hf1—C1^ii	52.7 (2)
C2^iv—Hf1—C1^i	130.0 (2)	C2^v—Hf1—C1^ii	94.8 (2)
C2—Hf1—C1^i	94.8 (2)	C1^i—Hf1—C1^ii	112.98 (12)
C2^v—Hf1—C1^i	152.2 (2)	C1^iii—Hf1—C1^ii	122.45 (4)
C2^i—Hf1—C1^iii	52.7 (2)	C1^iv—Hf1—C1^ii	112.98 (12)
C2^ii—Hf1—C1^iii	94.8 (2)	C1^v—Hf1—C1^ii	122.45 (4)
C2^iii—Hf1—C1^iii	32.0 (2)	C1—Hf1—C1^ii	31.4 (3)
C2^iv—Hf1—C1^iii	152.2 (2)	C1^ii—C1—C2	108.3 (4)
C2—Hf1—C1^iii	81.0 (2)	C1^ii—C1—Hf1	74.32 (14)
C2^v—Hf1—C1^iii	130.0 (2)	C2—C1—Hf1	72.9 (4)
C1^i—Hf1—C1^iii	31.4 (3)	C1^ii—C1—H1	125.9
C2^i—Hf1—C1^iv	81.0 (2)	C2—C1—H1	125.9
C2^ii—Hf1—C1^iv	130.0 (2)	Hf1—C1—H1	118.7
C2^iii—Hf1—C1^iv	94.8 (2)	C3—C2—C1	107.3 (6)
C2^iv—Hf1—C1^iv	32.0 (2)	C3—C2—Hf1	75.3 (5)
C2—Hf1—C1^iv	152.2 (2)	C1—C2—Hf1	75.0 (4)
C2^v—Hf1—C1^iv	52.7 (2)	C3—C2—H2	126.4
C1^i—Hf1—C1^iv	112.98 (12)	C1—C2—H2	126.4
C1^iii—Hf1—C1^iv	122.45 (4)	Hf1—C2—H2	115.6
C2^i—Hf1—C1^v	94.8 (2)	C2—C3—C2^ii	108.7 (8)
C2^ii—Hf1—C1^v	152.2 (2)	C2—C3—Hf1	73.0 (5)
C2^iii—Hf1—C1^v	81.0 (2)	C2^ii—C3—Hf1	73.0 (5)
C2^iv—Hf1—C1^v	52.7 (2)	C2—C3—H3	125.6
C2—Hf1—C1^v	130.0 (2)	C2^ii—C3—H3	125.6
C2^v—Hf1—C1^v	32.0 (2)	Hf1—C3—H3	120.2

Symmetry codes: (i) −x+y, −x+1, −z+1/2; (ii) x, y, −z+1/2; (iii) −x+y, −x+1, z; (iv) −y+1, x−y+1, −z+1/2; (v) −y+1, x−y+1, z.