Redetermination of di-μ-hydrido-hexa-hydridotetra-kis(tetra-hydro-furan)dialuminium(III)magnesium(II).

The structure of the title compound, [Mg(AlH(4))(2)(C(4)H(8)O)(4)], has been redetermined at 150 K. The Mg(II) ion is hexa-coordinated to four tetra-hydro-furan (THF) ligands, and two AlH(4) (-) anions through bridging H atoms. The Al-H distances are more precise compared to those previously determined [Nöth et al. (1995 ▶). Chem. Ber. 128, 999-1006; Fichtner & Fuhr (2002 ▶). J. Alloys Compd, 345, 386-396]. The mol-ecule has twofold rotation symmetry.

Related literature

For the synthesis of Mg(AlH4)2·4THF, see: Ashby et al. (1970 ▶); Shen & Che (1991 ▶); Nöth et al. (1995 ▶). For the synthesis of AlH4MgBH4, see: Ashby & Goel (1977 ▶). For previous determinations of the crystal structure of Mg(AlH4)2·4THF, see: Noth et al. (1995 ▶); Fichtner & Fuhr (2002 ▶). For the thermal decomposition properties of Mg(AlH4)2·4THF, see: Dilts & Ashby (1972 ▶). For other alanate structures, see: Sklar & Post (1967 ▶); Lauher et al. (1979 ▶); Fichtner & Fuhr (2002 ▶); Fichtner et al. (2004 ▶).

Experimental

Crystal data

[Al2MgH8(C4H8O)4]

M = 374.75

Orthorhombic,

a = 10.161 (2) Å

b = 14.027 (3) Å

c = 16.429 (3) Å

V = 2341.6 (8) Å3

Z = 4

Mo Kα radiation

μ = 0.16 mm−1

T = 150 K

0.38 × 0.31 × 0.19 mm

Data collection

Nonius Kappa CCD diffractometer

Absorption correction: multi-scan (SCALEPACK; Otwinowski & Minor, 1997 ▶) T min = 0.940, T max = 0.969

5018 measured reflections

2687 independent reflections

1973 reflections with I > 2σ(I)

R int = 0.017

Refinement

R[F 2 > 2σ(F 2)] = 0.041

wR(F 2) = 0.119

S = 1.07

2687 reflections

122 parameters

H atoms treated by a mixture of independent and constrained refinement

Δρmax = 0.30 e Å−3

Δρmin = −0.30 e Å−3

Data collection: COLLECT (Nonius, 1998 ▶); cell refinement: SCALEPACK (Otwinowski & Minor, 1997 ▶); data reduction: DENZO (Otwinowski & Minor 1997 ▶) and SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536810014200/ci5044sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810014200/ci5044Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

[Al2MgH8(C4H8O)4]	F(000) = 824
Mr = 374.75	Dx = 1.063 Mg m−3
Orthorhombic, Pcnb	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2b 2ac	Cell parameters from 2687 reflections
a = 10.161 (2) Å	θ = 2.4–27.5°
b = 14.027 (3) Å	µ = 0.16 mm−1
c = 16.429 (3) Å	T = 150 K
V = 2341.6 (8) Å3	Cube, colourless
Z = 4	0.38 × 0.31 × 0.19 mm

Nonius Kappa CCD diffractometer	2687 independent reflections
Radiation source: fine-focus sealed tube	1973 reflections with I > 2σ(I)
graphite	Rint = 0.017
φ and ω scans	θmax = 27.5°, θmin = 2.4°
Absorption correction: multi-scan (SCALEPACK; Otwinowski & Minor, 1997)	h = −13→13
Tmin = 0.940, Tmax = 0.969	k = −18→18
5018 measured reflections	l = −21→21

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.041	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.119	H atoms treated by a mixture of independent and constrained refinement
S = 1.07	w = 1/[σ2(Fo2) + (0.0615P)2 + 0.6568P] where P = (Fo2 + 2Fc2)/3
2687 reflections	(Δ/σ)max = 0.001
122 parameters	Δρmax = 0.30 e Å−3
0 restraints	Δρmin = −0.30 e Å−3

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

	x	y	z	Uiso*/Ueq
Al1	0.22387 (5)	0.44321 (4)	0.13620 (3)	0.03294 (17)
Mg1	0.0000	0.2500	0.13728 (4)	0.02116 (19)
O1	0.16625 (10)	0.16699 (8)	0.13767 (6)	0.0298 (3)
O3	0.0000	0.2500	0.01068 (8)	0.0269 (3)
O2	0.0000	0.2500	0.26391 (8)	0.0270 (3)
C8	−0.06993 (19)	0.23112 (14)	−0.12525 (9)	0.0429 (5)
H8A	−0.1341	0.2828	−0.1356	0.052*
H8B	−0.0815	0.1806	−0.1667	0.052*
C4	0.27768 (17)	0.17950 (14)	0.19205 (12)	0.0439 (5)
H4A	0.2588	0.1515	0.2461	0.053*
H4B	0.2982	0.2480	0.1991	0.053*
C5	0.02463 (19)	0.33286 (12)	0.31515 (9)	0.0370 (4)
H5A	−0.0285	0.3880	0.2967	0.044*
H5B	0.1189	0.3507	0.3136	0.044*
C7	−0.08466 (18)	0.19178 (13)	−0.04047 (9)	0.0382 (4)
H7A	−0.1773	0.1962	−0.0222	0.046*
H7B	−0.0570	0.1242	−0.0386	0.046*
C6	−0.0151 (2)	0.30305 (13)	0.39968 (10)	0.0445 (5)
H6A	−0.1098	0.3151	0.4094	0.053*
H6B	0.0373	0.3370	0.4415	0.053*
C2	0.3257 (2)	0.05289 (16)	0.10336 (13)	0.0573 (6)
H2A	0.3781	0.0396	0.0538	0.069*
H2B	0.3177	−0.0066	0.1354	0.069*
C3	0.3878 (2)	0.1296 (2)	0.15261 (16)	0.0763 (8)
H3A	0.4480	0.1022	0.1938	0.092*
H3B	0.4382	0.1737	0.1174	0.092*
C1	0.1945 (2)	0.09039 (16)	0.08170 (14)	0.0587 (6)
H1A	0.1945	0.1143	0.0250	0.070*
H1B	0.1272	0.0396	0.0865	0.070*
H1	0.1142 (17)	0.3641 (12)	0.1382 (9)	0.034 (5)*
H2	0.2892 (19)	0.4426 (13)	0.2215 (13)	0.055 (6)*
H3	0.3167 (19)	0.4126 (16)	0.0687 (13)	0.063 (6)*
H4	0.156 (2)	0.5361 (18)	0.1206 (14)	0.076 (7)*

	U11	U22	U33	U12	U13	U23
Al1	0.0350 (3)	0.0315 (3)	0.0323 (3)	−0.0085 (2)	−0.0024 (2)	0.0047 (2)
Mg1	0.0227 (4)	0.0223 (4)	0.0184 (3)	0.0009 (3)	0.000	0.000
O1	0.0284 (6)	0.0313 (6)	0.0297 (6)	0.0073 (5)	−0.0075 (4)	−0.0111 (4)
O3	0.0292 (8)	0.0336 (8)	0.0178 (7)	−0.0037 (6)	0.000	0.000
O2	0.0401 (9)	0.0208 (7)	0.0200 (7)	−0.0038 (7)	0.000	0.000
C8	0.0587 (12)	0.0459 (11)	0.0243 (8)	0.0041 (9)	−0.0085 (8)	−0.0006 (7)
C4	0.0391 (10)	0.0438 (10)	0.0488 (11)	0.0098 (8)	−0.0215 (8)	−0.0096 (9)
C5	0.0550 (11)	0.0294 (9)	0.0268 (8)	−0.0089 (8)	0.0003 (7)	−0.0075 (7)
C7	0.0442 (10)	0.0455 (10)	0.0249 (8)	−0.0094 (8)	−0.0090 (7)	−0.0014 (7)
C6	0.0556 (12)	0.0522 (12)	0.0257 (8)	−0.0139 (9)	0.0049 (8)	−0.0098 (8)
C2	0.0657 (14)	0.0601 (14)	0.0462 (11)	0.0366 (11)	−0.0033 (10)	−0.0097 (10)
C3	0.0344 (12)	0.107 (2)	0.0876 (17)	0.0248 (12)	−0.0139 (11)	−0.0386 (16)
C1	0.0526 (12)	0.0554 (13)	0.0681 (14)	0.0211 (10)	−0.0125 (10)	−0.0379 (11)

Al1—H1	1.573 (18)	C4—C3	1.471 (3)
Al1—H2	1.55 (2)	C4—H4A	0.99
Al1—H3	1.52 (2)	C4—H4B	0.99
Al1—H4	1.50 (2)	C5—C6	1.505 (2)
Mg1—O1i	2.0517 (11)	C5—H5A	0.99
Mg1—O1	2.0518 (11)	C5—H5B	0.99
Mg1—O3	2.0800 (15)	C7—H7A	0.99
Mg1—O2	2.0804 (15)	C7—H7B	0.99
Mg1—H1	1.977 (18)	C6—C6i	1.519 (4)
O1—C1	1.443 (2)	C6—H6A	0.99
O1—C4	1.4529 (19)	C6—H6B	0.99
O3—C7i	1.4537 (17)	C2—C1	1.477 (3)
O3—C7	1.4537 (17)	C2—C3	1.487 (3)
O2—C5	1.4567 (17)	C2—H2A	0.99
O2—C5i	1.4567 (17)	C2—H2B	0.99
C8—C7	1.506 (2)	C3—H3A	0.99
C8—C8i	1.517 (4)	C3—H3B	0.99
C8—H8A	0.99	C1—H1A	0.99
C8—H8B	0.99	C1—H1B	0.99
H1—Al1—H2	106.3 (9)	O2—C5—C6	105.40 (13)
H1—Al1—H3	104.8 (10)	O2—C5—H5A	110.7
H2—Al1—H3	113.1 (11)	C6—C5—H5A	110.7
H1—Al1—H4	107.0 (11)	O2—C5—H5B	110.7
H2—Al1—H4	110.9 (11)	C6—C5—H5B	110.7
H3—Al1—H4	114.0 (12)	H5A—C5—H5B	108.8
O1i—Mg1—O1	179.65 (6)	O3—C7—C8	105.66 (13)
O1i—Mg1—O3	90.18 (3)	O3—C7—H7A	110.6
O1—Mg1—O3	90.18 (3)	C8—C7—H7A	110.6
O1i—Mg1—O2	89.82 (3)	O3—C7—H7B	110.6
O1—Mg1—O2	89.82 (3)	C8—C7—H7B	110.6
O3—Mg1—O2	180.0	H7A—C7—H7B	108.7
O1i—Mg1—H1	91.4 (5)	C5—C6—C6i	102.59 (11)
O1—Mg1—H1	88.6 (5)	C5—C6—H6A	111.2
O3—Mg1—H1	90.4 (4)	C6i—C6—H6A	111.2
O2—Mg1—H1	89.6 (4)	C5—C6—H6B	111.2
C1—O1—C4	109.08 (13)	C6i—C6—H6B	111.2
C1—O1—Mg1	125.75 (10)	H6A—C6—H6B	109.2
C4—O1—Mg1	125.10 (10)	C1—C2—C3	104.88 (16)
C7i—O3—C7	109.37 (16)	C1—C2—H2A	110.8
C7i—O3—Mg1	125.32 (8)	C3—C2—H2A	110.8
C7—O3—Mg1	125.32 (8)	C1—C2—H2B	110.8
C5—O2—C5i	109.39 (16)	C3—C2—H2B	110.8
C5—O2—Mg1	125.30 (8)	H2A—C2—H2B	108.8
C5i—O2—Mg1	125.30 (8)	C4—C3—C2	105.13 (18)
C7—C8—C8i	102.78 (11)	C4—C3—H3A	110.7
C7—C8—H8A	111.2	C2—C3—H3A	110.7
C8i—C8—H8A	111.2	C4—C3—H3B	110.7
C7—C8—H8B	111.2	C2—C3—H3B	110.7
C8i—C8—H8B	111.2	H3A—C3—H3B	108.8
H8A—C8—H8B	109.1	O1—C1—C2	106.93 (15)
O1—C4—C3	105.34 (15)	O1—C1—H1A	110.3
O1—C4—H4A	110.7	C2—C1—H1A	110.3
C3—C4—H4A	110.7	O1—C1—H1B	110.3
O1—C4—H4B	110.7	C2—C1—H1B	110.3
C3—C4—H4B	110.7	H1A—C1—H1B	108.6
H4A—C4—H4B	108.8