Cubic di-μ-amido-bis­[bis(η⁵-cyclo­penta­dien­yl)ytterbium(III)]

The title compound, [Yb₂(C₅H₅)₄(NH₂)₂], was synthesized in a Parr high-pressure vessel starting from monoclinic [Cp₂YbNH₂]₂ (where Cp = cyclo­penta­dien­yl). The complex is located on a special position of site symmetry mmm with just an eighth of the complex in the asymmetric unit. The Yb atom is in a distorted tetra­hedral coordination environment, coordinated by two cyclo­penta­dienyl rings and two amino groups forming a dimeric complex bridged through the amino groups. This compound represents the high-pressure cubic modification of monoclinic [Cp₂YbNH₂]₂ obtained at 250 bar (1 bar = 10⁵ Pa) under an atmosphere of argon.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.008 Å
• R factor = 0.024
• wR factor = 0.051
• Data-to-parameter ratio = 23.4

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT241_ALERT_2_B Check High      Ueq as Compared to Neighbors for         C3
PLAT242_ALERT_2_B Check Low       Ueq as Compared to Neighbors for        Yb1
PLAT731_ALERT_1_B Bond    Calc     0.90(5), Rep   0.894(10) ......       5.00 su-Ra
              N1   -H11     1.555   1.555

Alert level C
PLAT062_ALERT_4_C Rescale T(min) & T(max) by .....................       0.84
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for         C2
PLAT420_ALERT_2_C D-H Without Acceptor       N1     -   H11    ...          ?

Alert level G
ABSTM02_ALERT_3_G  When printed, the submitted absorption T values will be
            replaced by the scaled T values. Since the ratio of scaled T's
            is identical to the ratio of reported T values, the scaling
            does not imply a change to the absorption corrections used in
            the study.
            Ratio of Tmax expected/reported      0.838
            Tmax scaled      0.327 Tmin scaled      0.134
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K
PLAT794_ALERT_5_G Check Predicted Bond Valency for Yb1         (3)       1.26
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          1

   0 ALERT level A = In general: serious problem
   3 ALERT level B = Potentially serious problem
   3 ALERT level C = Check and explain
   5 ALERT level G = General alerts; check

   3 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   4 ALERT type 2 Indicator that the structure model may be wrong or deficient
   2 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

The stucture of the title compound, [Cp₂YbNH₂]₂, shows the high-pressure cubic modification of the monoclinic compound [Cp₂YbNH₂]₂. The assymetric unit consists of three C atoms, one N atom and one Yb atom (figure 1). Gometric parameters of the title compound are in the usual ranges. It crystalizes isotyp with cubic [Cp₂ErNH₂]₂, which was the only cubic compound of the system [Cp₂LnNH₂]₂ so far.

Related literature

The monoclinic [Cp₂YbNH₂]₂ complex was first described by Fischer & Fischer (1966). The first single X-ray diffraction data of this compound were presented by Baisch, Pagano, Zeuner, Barros et al. (2006). For related literature, see Schumann et al. (1995); Hayes & Thomas (1989); Hammel & Weidlein (1990); Baisch, Pagano, Zeuner & Schnick (2006).

S2. Experimental

Anhydrous ammonia was condensed at 195 K (dry ice, iPrOH) onto YpCp₃ (4–10 mmol). The resulting colourless mixture was stirred rapidly for 5 h and then further stirred for additional 6 - 24 h without further cooling. After complete evaporation of residual ammonia the pale-coloured solid was dried under vakuum and sublimed under reduced pressure yielding green Cp₃YbNH₃. Heating of Cp₃YbNH₃ to 523 K yielded yellow monoclinic [Cp₂YbNH₂]₂. Subsequent treatment of this compound to 250 bar yielded yellow cubic [Cp₂YbNH₂]₂.

S3. Refinement

The H atoms bonded to C were positioned geometrically and refined using a riding model, C—H = 0.93 A and U_iso(H) = 1.2 U_iso(C). The amino H atom was freely refined.

Computing details

Data collection: X-AREA (Stoe & Cie, 2002); cell refinement: X-AREA (Stoe & Cie, 2002); data reduction: X-AREA (Stoe & Cie, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg 1999); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures

	Fig. 1. A view of the title compound showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. shows the crystal packing diagram of the title compound viewed along the c axis.

di-µ-amido-bis[bis(η⁵-cyclopentadienyl)ytterbium(III)]

Crystal data

[Yb2(C5H5)4(NH2)2]	Melting point: not measured K
Mr = 638.5	Mo Kα radiation, λ = 0.71073 Å
Cubic, Im3	Cell parameters from 6512 reflections
Hall symbol: -I223	θ = 4.6–60.9°
a = 14.4104 (17) Å	µ = 9.32 mm^−1
V = 2992.5 (6) Å^3	T = 293 K
Z = 6	Platelet, yellow
F(000) = 1788	0.22 × 0.17 × 0.12 mm
Dx = 2.126 Mg m^−3

Data collection

Stoe IPDS diffractometer	843 independent reflections
Radiation source: fine-focus sealed tube	578 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.080
oscillation scans	θmax = 30.4°, θmin = 2.8°
Absorption correction: multi-scan correction based on equivalents (XPREP in SHELXTL-Plus; Sheldrick, 1996)	h = −20→20
Tmin = 0.160, Tmax = 0.390	k = −20→20
16043 measured reflections	l = −20→20

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)] = 0.025	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.051	H atoms treated by a mixture of independent and constrained refinement
S = 0.87	w = 1/[σ^2(Fo^2) + (0.0285P)^2] where P = (Fo^2 + 2Fc^2)/3
843 reflections	(Δ/σ)max < 0.001
36 parameters	Δρmax = 0.58 e Å^−3
1 restraint	Δρmin = −0.50 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
Yb1	0.5000	0.12174 (2)	0.5000	0.03854 (11)
N1	0.5000	0.0000	0.6022 (4)	0.0400 (14)
C1	0.3244 (3)	0.1320 (4)	0.4523 (4)	0.0776 (17)
H1	0.3009	0.0854	0.4143	0.093*
C2	0.3644 (4)	0.2112 (5)	0.4235 (5)	0.090 (2)
H2	0.3739	0.2286	0.3621	0.108*
C3	0.3888 (6)	0.2621 (5)	0.5000	0.105 (4)
H3	0.4167	0.3202	0.5000	0.126*
H11	0.551 (3)	0.0000	0.638 (4)	0.07 (2)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Yb1	0.03668 (19)	0.03207 (18)	0.0469 (2)	0.000	0.000	0.000
N1	0.044 (4)	0.049 (4)	0.026 (3)	0.000	0.000	0.000
C1	0.040 (2)	0.071 (3)	0.122 (4)	0.015 (2)	−0.018 (2)	−0.026 (3)
C2	0.068 (4)	0.103 (5)	0.100 (5)	0.034 (4)	−0.004 (3)	0.036 (4)
C3	0.057 (5)	0.036 (4)	0.224 (14)	0.018 (3)	0.000	0.000

Geometric parameters (Å, º)

Yb1—N1^i	2.291 (4)	Yb1—C1^iv	2.626 (5)
Yb1—N1	2.291 (4)	Yb1—H11	2.75 (3)
Yb1—C3^ii	2.580 (6)	N1—Yb1^i	2.291 (4)
Yb1—C3	2.580 (6)	N1—H11	0.894 (10)
Yb1—C2^iii	2.588 (5)	C1—C2	1.344 (8)
Yb1—C2^ii	2.588 (5)	C1—C1^iii	1.376 (12)
Yb1—C2	2.588 (5)	C1—H1	0.9300
Yb1—C2^iv	2.588 (5)	C2—C3	1.369 (8)
Yb1—C1^iii	2.626 (5)	C2—H2	0.9300
Yb1—C1	2.626 (5)	C3—C2^iii	1.369 (8)
Yb1—C1^ii	2.626 (5)	C3—H3	0.9300
N1^i—Yb1—N1	80.1 (2)	C2^ii—Yb1—C1^ii	29.87 (19)
N1^i—Yb1—C3^ii	126.87 (15)	C2—Yb1—C1^ii	144.2 (2)
N1—Yb1—C3^ii	126.87 (15)	C2^iv—Yb1—C1^ii	49.90 (19)
N1^i—Yb1—C3	126.87 (15)	C1^iii—Yb1—C1^ii	148.9 (3)
N1—Yb1—C3	126.87 (15)	C1—Yb1—C1^ii	173.6 (2)
C3^ii—Yb1—C3	76.8 (4)	N1^i—Yb1—C1^iv	82.80 (12)
N1^i—Yb1—C2^iii	130.95 (16)	N1—Yb1—C1^iv	102.21 (14)
N1—Yb1—C2^iii	96.19 (19)	C3^ii—Yb1—C1^iv	50.0 (2)
C3^ii—Yb1—C2^iii	94.5 (3)	C3—Yb1—C1^iv	123.7 (3)
C3—Yb1—C2^iii	30.72 (18)	C2^iii—Yb1—C1^iv	144.2 (2)
N1^i—Yb1—C2^ii	130.95 (16)	C2^ii—Yb1—C1^iv	49.90 (19)
N1—Yb1—C2^ii	96.19 (19)	C2—Yb1—C1^iv	126.0 (2)
C3^ii—Yb1—C2^ii	30.72 (18)	C2^iv—Yb1—C1^iv	29.87 (19)
C3—Yb1—C2^ii	94.5 (3)	C1^iii—Yb1—C1^iv	173.6 (2)
C2^iii—Yb1—C2^ii	98.1 (3)	C1—Yb1—C1^iv	148.9 (3)
N1^i—Yb1—C2	96.19 (19)	C1^ii—Yb1—C1^iv	30.4 (3)
N1—Yb1—C2	130.95 (16)	N1^i—Yb1—H11	88.7 (8)
C3^ii—Yb1—C2	94.5 (3)	N1—Yb1—H11	17.5 (5)
C3—Yb1—C2	30.72 (18)	C3^ii—Yb1—H11	109.6 (4)
C2^iii—Yb1—C2	50.4 (3)	C3—Yb1—H11	131.6 (12)
C2^ii—Yb1—C2	120.2 (3)	C2^iii—Yb1—H11	102.1 (13)
N1^i—Yb1—C2^iv	96.19 (19)	C2^ii—Yb1—H11	79.0 (4)
N1—Yb1—C2^iv	130.95 (16)	C2—Yb1—H11	145.7 (12)
C3^ii—Yb1—C2^iv	30.72 (18)	C2^iv—Yb1—H11	115.2 (10)
C3—Yb1—C2^iv	94.5 (3)	C1^iii—Yb1—H11	95.8 (12)
C2^iii—Yb1—C2^iv	120.2 (3)	C1—Yb1—H11	118.7 (9)
C2^ii—Yb1—C2^iv	50.4 (3)	C1^ii—Yb1—H11	65.9 (8)
C2—Yb1—C2^iv	98.1 (3)	C1^iv—Yb1—H11	88.3 (12)
N1^i—Yb1—C1^iii	102.21 (14)	Yb1^i—N1—Yb1	99.9 (2)
N1—Yb1—C1^iii	82.80 (12)	Yb1^i—N1—H11	112 (3)
C3^ii—Yb1—C1^iii	123.7 (3)	Yb1—N1—H11	112 (3)
C3—Yb1—C1^iii	50.0 (2)	C2—C1—C1^iii	107.9 (4)
C2^iii—Yb1—C1^iii	29.87 (19)	C2—C1—Yb1	73.5 (3)
C2^ii—Yb1—C1^iii	126.0 (2)	C1^iii—C1—Yb1	74.82 (13)
C2—Yb1—C1^iii	49.90 (19)	C2—C1—H1	126.0
C2^iv—Yb1—C1^iii	144.2 (2)	C1^iii—C1—H1	126.0
N1^i—Yb1—C1	82.80 (12)	Yb1—C1—H1	117.7
N1—Yb1—C1	102.21 (14)	C1—C2—C3	108.5 (7)
C3^ii—Yb1—C1	123.7 (3)	C1—C2—Yb1	76.6 (3)
C3—Yb1—C1	50.0 (2)	C3—C2—Yb1	74.3 (4)
C2^iii—Yb1—C1	49.90 (19)	C1—C2—H2	125.8
C2^ii—Yb1—C1	144.2 (2)	C3—C2—H2	125.8
C2—Yb1—C1	29.87 (19)	Yb1—C2—H2	115.4
C2^iv—Yb1—C1	126.0 (2)	C2^iii—C3—C2	107.2 (9)
C1^iii—Yb1—C1	30.4 (3)	C2^iii—C3—Yb1	74.9 (3)
N1^i—Yb1—C1^ii	102.21 (14)	C2—C3—Yb1	74.9 (3)
N1—Yb1—C1^ii	82.80 (12)	C2^iii—C3—H3	126.4
C3^ii—Yb1—C1^ii	50.0 (2)	C2—C3—H3	126.4
C3—Yb1—C1^ii	123.7 (3)	Yb1—C3—H3	116.0
C2^iii—Yb1—C1^ii	126.0 (2)

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