Structure of unsolvated magnesium borohydride Mg(BH₄)₂

We have determined the structures of two phases of unsolvated Mg(BH₄)₂, a material of interest for hydrogen storage. One or both phases can be obtained depending on the synthesis conditions. The first, a hexagonal phase with space group P6₁, is stable below 453 K. Upon heating above that temperature it transforms to an orthorhombic phase, with space group Fddd, stable to 613 K at which point it decomposes with hydrogen release. Both phases consist of complex networks of corner-sharing tetrahedra consisting of a central Mg atom and four BH₄ units. The high-temperature orthorhombic phase has a strong antisite disorder in the a lattice direction, which can be understood on the basis of atomic structure.

Computing details

For both compounds, data collection: SPEC; cell refinement: TOPAS-Academic; data reduction: TOPAS-Academic. Program(s) used to solve structure: EXPO for MgB2H8_LT; TOPAS-Academic for MgB2H8_HT. For both compounds, program(s) used to refine structure: TOPAS-Academic.

(MgB2H8_LT) Magnesium borohydrides

Crystal data

MgB2H8	Z = 30
Mr = 53.99	Synchrotron radiation, λ = 0.700319 Å
Hexagonal, P61	µ = 1.39 mm^−1
a = 10.3414 (4) Å	T = 293 K
c = 37.086 (2) Å	white
V = 3434.7 (3) Å^3

Data collection

Huber diffractometer	Data collection mode: transmission
Radiation source: synchrotron	Scan method: step
Si(111) channel cut monochromator	2θmin = 2.0°, 2θmax = 42.000°, 2θstep = 0.005°
Specimen mounting: capillary

Refinement

Rp = 0.036	126 parameters
Rwp = 0.046	H-atom parameters constrained
Rexp = 0.039	Weighting scheme based on measured s.u.'s 1/(sigma*sigma)
RBragg = 0.010	(Δ/σ)max < 0.001
8001 data points	Background function: Chebyshev polynomial with 34 coefficients
Excluded region(s): none	Preferred orientation correction: none
Profile function: Simple_Axial_model function with Rp=9999,Rs=330 in TOPAS-Academic

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

	x	y	z	Biso*/Beq
Mg1	0.0323 (4)	0.5216 (7)	0.78683	2.37 (5)
Mg2	0.6666 (5)	0.0485 (7)	0.8367 (2)	2.37 (5)
Mg3	0.9989 (16)	0.8685 (9)	0.8689 (4)	2.37 (5)
Mg4	0.9642 (4)	0.4866 (4)	0.94716 (11)	2.37 (5)
Mg5	0.9473 (8)	0.3421 (4)	0.0669 (2)	2.37 (5)
B6	0.8236 (6)	0.9491 (8)	0.8524 (8)	2.4 (1)
H6a	0.816756	1.041366	0.866659	2.4 (1)
H6b	0.931656	0.997118	0.837090	2.4 (1)
H6c	0.727466	0.891880	0.833061	2.4 (1)
H6d	0.818323	0.866037	0.872710	2.4 (1)
B7	0.019 (3)	0.467 (2)	0.0097 (2)	2.4 (1)
H7a	0.104181	0.500506	0.031837	2.4 (1)
H7b	−0.095960	0.412583	0.021788	2.4 (1)
H7c	0.028298	0.386752	−0.008977	2.4 (1)
H7d	0.039842	0.569319	−0.005768	2.4 (1)
B8	0.6912 (6)	0.2782 (13)	0.9547 (8)	2.4 (1)
H8a	0.579486	0.246162	0.966790	2.4 (1)
H8b	0.716866	0.185970	0.959292	2.4 (1)
H8c	0.779781	0.383576	0.967725	2.4 (1)
H8d	0.688547	0.297053	0.924912	2.4 (1)
B9	0.7095 (18)	0.134 (2)	0.0853 (2)	2.4 (1)
H9a	0.654498	0.187465	0.100559	2.4 (1)
H9b	0.722403	0.169029	0.056218	2.4 (1)
H9c	0.638463	0.009194	0.087159	2.4 (1)
H9d	0.822436	0.170472	0.097224	2.4 (1)
B10	0.9717 (8)	0.700 (3)	0.9180 (7)	2.4 (1)
H10a	0.927772	0.578440	0.911638	2.4 (1)
H10b	0.994052	0.718601	0.947717	2.4 (1)
H10c	0.886753	0.731676	0.909891	2.4 (1)
H10d	1.078223	0.769763	0.902674	2.4 (1)
B11	0.843 (2)	0.3137 (13)	0.8210 (4)	2.4 (1)
H11a	0.850536	0.239285	0.800029	2.4 (1)
H11b	0.751772	0.244053	0.840669	2.4 (1)
H11c	0.817677	0.395911	0.807567	2.4 (1)
H11d	0.952416	0.375712	0.835735	2.4 (1)
B12	1.0073 (19)	0.703 (3)	0.8241 (7)	2.4 (1)
H12a	1.097183	0.821748	0.829154	2.4 (1)
H12b	0.980215	0.687265	0.794492	2.4 (1)
H12c	0.904481	0.678542	0.839745	2.4 (1)
H12d	1.047401	0.625245	0.832889	2.4 (1)
B13	0.1888 (15)	0.1229 (18)	0.8896 (8)	2.4 (1)
H13a	0.080505	0.032791	0.901181	2.4 (1)
H13b	0.278109	0.163125	0.910877	2.4 (1)
H13c	0.174836	0.218525	0.880289	2.4 (1)
H13d	0.221870	0.076959	0.866133	2.4 (1)
B14	0.509 (2)	0.992 (2)	0.8894 (3)	2.4 (1)
H14a	0.557664	1.103886	0.875596	2.4 (1)
H14b	0.591738	0.994041	0.909196	2.4 (1)
H14c	0.481510	0.902932	0.868709	2.4 (1)
H14d	0.404009	0.968821	0.904019	2.4 (1)
B15	0.9820 (10)	0.4776 (13)	0.1224 (3)	2.4 (1)
H15a	0.899606	0.403882	0.143350	2.4 (1)
H15b	1.040806	0.596517	0.132047	2.4 (1)
H15c	0.921543	0.469062	0.096533	2.4 (1)
H15d	1.066205	0.440940	0.117590	2.4 (1)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
?	?	?	?	?	?	?

Geometric parameters (Å, º)

H6a—B6	1.124	B9—H9c	1.124
H6a—Mg2	1.939	B9—H9d	1.124
H6b—B6	1.124	B9—Mg4	2.397
H6b—Mg3	2.138	B9—Mg5	2.419
H6c—B6	1.124	B10—H10a	1.124
H6c—Mg2	2.014	B10—H10b	1.124
H6d—B6	1.124	B10—H10c	1.124
H6d—Mg3	1.860	B10—H10d	1.124
H7a—B7	1.124	B10—Mg4	2.420
H7a—Mg5^i	2.085	B10—Mg3	2.439
H7b—B7	1.124	B11—H11c	1.124
H7b—Mg5^i	1.963	B11—H11a	1.124
H7c—B7	1.124	B11—H11b	1.124
H7d—B7	1.124	B11—H11d	1.124
H7d—Mg4	1.929	B11—Mg1^ii	2.418
H8a—B8	1.124	B11—Mg2	2.488
H8a—Mg1	2.016	B12—H12a	1.124
H8b—B8	1.124	B12—H12c	1.124
H8b—Mg1	1.931	B12—H12b	1.124
H8c—B8	1.124	B12—H12d	1.124
H8c—Mg4	1.822	B12—Mg3	2.417
H8d—B8	1.124	B12—Mg1^iii	2.447
H9a—B9	1.124	B13—H13a	1.124
H9a—Mg4	2.167	B13—H13b	1.124
H9b—B9	1.124	B13—H13c	1.124
H9b—Mg5	2.146	B13—H13d	1.124
H9c—B9	1.124	B13—Mg5^iv	2.473
H9c—Mg4	1.786	B13—Mg3	2.490
H9d—B9	1.124	B14—H14a	1.124
H9d—Mg5	1.947	B14—H14c	1.124
H10a—B10	1.124	B14—H14d	1.124
H10a—Mg4	1.771	B14—H14b	1.124
H10b—B10	1.124	B14—Mg1^iv	2.412
H10c—B10	1.124	B14—Mg2	2.423
H10c—Mg3	2.004	B15—H15c	1.124
H10d—B10	1.124	B15—H15a	1.124
H10d—Mg3	2.030	B15—H15b	1.124
H11a—B11	1.124	B15—H15d	1.124
H11b—B11	1.124	B15—Mg2^v	2.408
H11b—Mg2	1.762	B15—Mg5	2.414
H11c—B11	1.124	Mg1—H8b	1.931
H11c—Mg1^ii	2.079	Mg1—H14b^vi	1.972
H11d—B11	1.124	Mg1—H12d^i	1.981
H12a—B12	1.124	Mg1—H8a	2.016
H12a—Mg3	1.983	Mg1—H12b^i	2.057
H12b—B12	1.124	Mg1—H14d^vi	2.072
H12b—Mg1^iii	2.057	Mg1—H11c^vii	2.079
H12c—B12	1.124	Mg1—B8	2.281
H12c—Mg3	2.016	Mg1—B14^vi	2.412
H12d—B12	1.124	Mg1—B11^vii	2.418
H12d—Mg1^iii	1.981	Mg1—B12^i	2.447
H13a—B13	1.124	Mg2—H15b^viii	1.760
H13a—Mg3	1.897	Mg2—H11b	1.762
H13b—B13	1.124	Mg2—H6a	1.939
H13c—B13	1.124	Mg2—H6c	2.014
H13c—Mg5^iv	1.925	Mg2—H14a	2.079
H13d—B13	1.124	Mg2—H14c	2.111
H14a—B14	1.124	Mg2—B6	2.386
H14a—Mg2	2.079	Mg2—B15^viii	2.408
H14b—B14	1.124	Mg2—B14	2.423
H14b—Mg1^iv	1.972	Mg2—B11	2.488
H14c—B14	1.124	Mg3—H6d	1.860
H14c—Mg2	2.111	Mg3—H13a	1.897
H14d—B14	1.124	Mg3—H12a	1.983
H14d—Mg1^iv	2.072	Mg3—H10c	2.004
H15a—B15	1.124	Mg3—H12c	2.016
H15b—B15	1.124	Mg3—H10d	2.030
H15b—Mg2^v	1.760	Mg3—H6b	2.138
H15c—B15	1.124	Mg3—B12	2.417
H15c—Mg5	1.832	Mg3—B6	2.423
H15d—B15	1.124	Mg3—B10	2.439
B6—H6a	1.124	Mg3—B13	2.490
B6—H6b	1.124	Mg4—H10a	1.771
B6—H6c	1.124	Mg4—H9c	1.786
B6—H6d	1.124	Mg4—H8c	1.822
B6—Mg2	2.386	Mg4—H7d	1.929
B6—Mg3	2.423	Mg4—H9a	2.167
B7—H7a	1.124	Mg4—B9	2.397
B7—H7b	1.124	Mg4—B10	2.420
B7—H7c	1.124	Mg4—B7	2.421
B7—H7d	1.124	Mg4—B8	2.571
B7—Mg5^i	2.400	Mg5—H15c	1.832
B7—Mg4	2.421	Mg5—H13c^vi	1.925
B8—H8a	1.124	Mg5—H9d	1.947
B8—H8b	1.124	Mg5—H7b^iii	1.963
B8—H8c	1.124	Mg5—H7a^iii	2.085
B8—H8d	1.124	Mg5—H9b	2.146
B8—Mg1	2.281	Mg5—B7^iii	2.400
B8—Mg4	2.571	Mg5—B15	2.414
B9—H9a	1.124	Mg5—B9	2.419
B9—H9b	1.124	Mg5—B13^vi	2.473
B6—H6a—Mg2	98.83	H8a—Mg1—H14d^vi	113.83
B6—H6b—Mg3	90.45	H8a—Mg1—H11c^vii	143.66
B6—H6c—Mg2	94.76	H8a—Mg1—B8	29.50
B6—H6d—Mg3	105.92	H8a—Mg1—B14^vi	113.38
B7—H7a—Mg5^i	91.84	H8a—Mg1—B11^vii	129.21
B7—H7b—Mg5^i	98.37	H8a—Mg1—B12^i	77.78
B7—H7d—Mg4	101.64	H12b^i—Mg1—H14d^vi	72.49
B8—H8a—Mg1	88.42	H12b^i—Mg1—H11c^vii	80.04
B8—H8b—Mg1	92.82	H12b^i—Mg1—B8	117.89
B8—H8c—Mg4	119.64	H12b^i—Mg1—B14^vi	100.17
B9—H9a—Mg4	87.47	H12b^i—Mg1—B11^vii	103.61
B9—H9b—Mg5	89.81	H12b^i—Mg1—B12^i	27.17
B9—H9c—Mg4	108.78	H14d^vi—Mg1—H11c^vii	96.19
B9—H9d—Mg5	100.51	H14d^vi—Mg1—B8	112.31
B10—H10a—Mg4	111.50	H14d^vi—Mg1—B14^vi	27.72
B10—H10c—Mg3	98.56	H14d^vi—Mg1—B11^vii	116.93
B10—H10d—Mg3	97.13	H14d^vi—Mg1—B12^i	99.65
B11—H11b—Mg2	117.35	H11c^vii—Mg1—B8	149.49
B11—H11c—Mg1^ii	93.23	H11c^vii—Mg1—B14^vi	102.74
B12—H12a—Mg3	98.37	H11c^vii—Mg1—B11^vii	27.64
B12—H12b—Mg1^iii	96.14	H11c^vii—Mg1—B12^i	77.38
B12—H12c—Mg3	96.54	B8—Mg1—B14^vi	98.16
B12—H12d—Mg1^iii	100.36	B8—Mg1—B11^vii	122.69
B13—H13a—Mg3	108.32	B8—Mg1—B12^i	106.94
B13—H13c—Mg5^iv	105.37	B14^vi—Mg1—B11^vii	112.05
B14—H14a—Mg2	93.48	B14^vi—Mg1—B12^i	127.30
B14—H14b—Mg1^iv	98.62	B11^vii—Mg1—B12^i	92.14
B14—H14c—Mg2	91.82	H15b^viii—Mg2—H11b	119.27
B14—H14d—Mg1^iv	93.23	H15b^viii—Mg2—H6a	139.71
B15—H15b—Mg2^v	111.33	H15b^viii—Mg2—H6c	84.71
B15—H15c—Mg5	107.07	H15b^viii—Mg2—H14a	113.52
H6a—B6—H6b	109.47	H15b^viii—Mg2—H14c	87.43
H6a—B6—H6c	109.48	H15b^viii—Mg2—B6	111.98
H6a—B6—H6d	109.47	H15b^viii—Mg2—B15^viii	25.77
H6a—B6—Mg2	53.44	H15b^viii—Mg2—B14	109.61
H6a—B6—Mg3	123.25	H15b^viii—Mg2—B11	108.48
H6b—B6—H6c	109.47	H11b—Mg2—H6a	92.64
H6b—B6—H6d	109.48	H11b—Mg2—H6c	138.66
H6b—B6—Mg2	115.30	H11b—Mg2—H14a	69.80
H6b—B6—Mg3	61.92	H11b—Mg2—H14c	121.75
H6c—B6—H6d	109.47	H11b—Mg2—B6	114.65
H6c—B6—Mg2	57.25	H11b—Mg2—B15^viii	97.12
H6c—B6—Mg3	126.64	H11b—Mg2—B14	95.62
H6d—B6—Mg2	135.17	H11b—Mg2—B11	23.65
H6d—B6—Mg3	47.59	H6a—Mg2—H6c	55.28
Mg2—B6—Mg3	175.44	H6a—Mg2—H14a	99.68
H7a—B7—H7b	109.46	H6a—Mg2—H14c	96.27
H7a—B7—H7c	109.48	H6a—Mg2—B6	27.74
H7a—B7—H7d	109.47	H6a—Mg2—B15^viii	164.77
H7a—B7—Mg5^i	60.25	H6a—Mg2—B14	89.21
H7a—B7—Mg4	148.72	H6a—Mg2—B11	90.93
H7b—B7—H7c	109.47	H6c—Mg2—H14a	134.34
H7b—B7—H7d	109.47	H6c—Mg2—H14c	90.07
H7b—B7—Mg5^i	54.03	H6c—Mg2—B6	27.99
H7b—B7—Mg4	100.97	H6c—Mg2—B15^viii	110.45
H7c—B7—H7d	109.46	H6c—Mg2—B14	107.84
H7c—B7—Mg5^i	105.25	H6c—Mg2—B11	121.27
H7c—B7—Mg4	65.17	H14a—Mg2—H14c	51.94
H7d—B7—Mg5^i	145.13	H14a—Mg2—B6	121.95
H7d—B7—Mg4	51.32	H14a—Mg2—B15^viii	94.67
Mg5^i—B7—Mg4	150.36	H14a—Mg2—B14	27.58
H8a—B8—H8b	109.47	H14a—Mg2—B11	93.35
H8a—B8—H8c	109.48	H14c—Mg2—B6	97.23
H8a—B8—H8d	109.48	H14c—Mg2—B15^viii	88.52
H8a—B8—Mg1	62.08	H14c—Mg2—B14	27.62
H8a—B8—Mg4	145.73	H14c—Mg2—B11	145.25
H8b—B8—H8c	109.48	B6—Mg2—B15^viii	137.35
H8b—B8—H8d	109.46	B6—Mg2—B14	102.89
H8b—B8—Mg1	57.71	B6—Mg2—B11	104.48
H8b—B8—Mg4	95.83	B15^viii—Mg2—B14	101.39
H8c—B8—H8d	109.46	B15^viii—Mg2—B11	93.33
H8c—B8—Mg1	154.85	B14—Mg2—B11	119.20
H8c—B8—Mg4	38.03	H6d—Mg3—H13a	87.60
H8d—B8—Mg1	95.58	H6d—Mg3—H12a	133.36
H8d—B8—Mg4	81.93	H6d—Mg3—H10c	73.15
Mg1—B8—Mg4	151.14	H6d—Mg3—H12c	91.93
H9a—B9—H9b	109.47	H6d—Mg3—H10d	126.99
H9a—B9—H9c	109.47	H6d—Mg3—H6b	54.10
H9a—B9—H9d	109.46	H6d—Mg3—B12	115.69
H9a—B9—Mg4	64.60	H6d—Mg3—B6	26.49
H9a—B9—Mg5	104.15	H6d—Mg3—B10	100.25
H9b—B9—H9c	109.47	H6d—Mg3—B13	104.30
H9b—B9—H9d	109.49	H13a—Mg3—H12a	129.41
H9b—B9—Mg4	125.04	H13a—Mg3—H10c	89.70
H9b—B9—Mg5	62.51	H13a—Mg3—H12c	173.32
H9c—B9—H9d	109.47	H13a—Mg3—H10d	87.16
H9c—B9—Mg4	44.86	H13a—Mg3—H6b	85.89
H9c—B9—Mg5	145.96	H13a—Mg3—B12	155.55
H9d—B9—Mg4	124.28	H13a—Mg3—B6	85.73
H9d—B9—Mg5	52.32	H13a—Mg3—B10	90.61
Mg4—B9—Mg5	167.48	H13a—Mg3—B13	25.36
H10a—B10—H10b	109.47	H12a—Mg3—H10c	125.33
H10a—B10—H10c	109.47	H12a—Mg3—H12c	54.63
H10a—B10—H10d	109.47	H12a—Mg3—H10d	87.19
H10a—B10—Mg4	42.91	H12a—Mg3—H6b	96.16
H10a—B10—Mg3	118.67	H12a—Mg3—B12	27.39
H10b—B10—H10c	109.47	H12a—Mg3—B6	117.32
H10b—B10—H10d	109.48	H12a—Mg3—B10	105.67
H10b—B10—Mg4	68.30	H12a—Mg3—B13	104.90
H10b—B10—Mg3	131.86	H10c—Mg3—H12c	83.79
H10c—B10—H10d	109.47	H10c—Mg3—H10d	54.11
H10c—B10—Mg4	135.53	H10c—Mg3—H6b	127.18
H10c—B10—Mg3	54.34	H10c—Mg3—B12	103.62
H10d—B10—Mg4	112.86	H10c—Mg3—B6	99.56
H10d—B10—Mg3	55.67	H10c—Mg3—B10	27.10
Mg4—B10—Mg3	157.65	H10c—Mg3—B13	112.58
H11c—B11—H11a	109.48	H12c—Mg3—H10d	87.80
H11c—B11—H11b	109.47	H12c—Mg3—H6b	99.24
H11c—B11—H11d	109.47	H12c—Mg3—B12	27.51
H11c—B11—Mg1^ii	59.13	H12c—Mg3—B6	96.80
H11c—B11—Mg2	128.16	H12c—Mg3—B10	82.91
H11a—B11—H11b	109.47	H12c—Mg3—B13	159.53
H11a—B11—H11d	109.47	H10d—Mg3—H6b	172.91
H11a—B11—Mg1^ii	86.80	H10d—Mg3—B12	84.40
H11a—B11—Mg2	70.76	H10d—Mg3—B6	152.77
H11b—B11—H11d	109.46	H10d—Mg3—B10	27.20
H11b—B11—Mg1^ii	163.17	H10d—Mg3—B13	92.13
H11b—B11—Mg2	38.99	H6b—Mg3—B12	101.44
H11d—B11—Mg1^ii	67.16	H6b—Mg3—B6	27.63
H11d—B11—Mg2	119.26	H6b—Mg3—B10	154.19
Mg1^ii—B11—Mg2	157.56	H6b—Mg3—B13	80.97
H12a—B12—H12c	109.48	B12—Mg3—B6	111.54
H12a—B12—H12b	109.46	B12—Mg3—B10	92.24
H12a—B12—H12d	109.48	B12—Mg3—B13	132.14
H12a—B12—Mg3	54.25	B6—Mg3—B10	126.64
H12a—B12—Mg1^iii	125.79	B6—Mg3—B13	92.59
H12c—B12—H12b	109.47	B10—Mg3—B13	105.88
H12c—B12—H12d	109.47	H10a—Mg4—H9c	98.30
H12c—B12—Mg3	55.95	H10a—Mg4—H8c	100.61
H12c—B12—Mg1^iii	124.68	H10a—Mg4—H7d	125.69
H12b—B12—H12d	109.47	H10a—Mg4—H9a	101.60
H12b—B12—Mg3	132.90	H10a—Mg4—B9	101.28
H12b—B12—Mg1^iii	56.69	H10a—Mg4—B10	25.60
H12d—B12—Mg3	117.62	H10a—Mg4—B7	151.51
H12d—B12—Mg1^iii	52.78	H10a—Mg4—B8	95.26
Mg3—B12—Mg1^iii	170.41	H9c—Mg4—H8c	112.76
H13a—B13—H13b	109.47	H9c—Mg4—H7d	127.91
H13a—B13—H13c	109.47	H9c—Mg4—H9a	54.28
H13a—B13—H13d	109.47	H9c—Mg4—B9	26.35
H13a—B13—Mg5^iv	133.49	H9c—Mg4—B10	117.55
H13a—B13—Mg3	46.32	H9c—Mg4—B7	108.95
H13b—B13—H13c	109.47	H9c—Mg4—B8	92.46
H13b—B13—H13d	109.48	H8c—Mg4—H7d	87.39
H13b—B13—Mg5^iv	61.74	H8c—Mg4—H9a	155.77
H13b—B13—Mg3	132.52	H8c—Mg4—B9	136.13
H13c—B13—H13d	109.47	H8c—Mg4—B10	105.52
H13c—B13—Mg5^iv	48.64	H8c—Mg4—B7	76.75
H13c—B13—Mg3	117.02	H8c—Mg4—B8	22.33
H13d—B13—Mg5^iv	116.48	H7d—Mg4—H9a	87.49
H13d—B13—Mg3	63.93	H7d—Mg4—B9	109.21
Mg5^iv—B13—Mg3	165.61	H7d—Mg4—B10	100.36
H14a—B14—H14c	109.48	H7d—Mg4—B7	27.05
H14a—B14—H14d	109.47	H7d—Mg4—B8	107.79
H14a—B14—H14b	109.47	H9a—Mg4—B9	27.93
H14a—B14—Mg1^iv	108.17	H9a—Mg4—B10	98.70
H14a—B14—Mg2	58.94	H9a—Mg4—B7	88.16
H14c—B14—H14d	109.47	H9a—Mg4—B8	144.29
H14c—B14—H14b	109.47	B9—Mg4—B10	110.59
H14c—B14—Mg1^iv	142.25	B9—Mg4—B7	99.64
H14c—B14—Mg2	60.56	B9—Mg4—B8	117.91
H14d—B14—H14b	109.46	B10—Mg4—B7	126.99
H14d—B14—Mg1^iv	59.05	B10—Mg4—B8	109.50
H14d—B14—Mg2	154.49	B7—Mg4—B8	91.80
H14b—B14—Mg1^iv	53.94	H15c—Mg5—H13c^vi	164.61
H14b—B14—Mg2	96.04	H15c—Mg5—H9d	92.19
Mg1^iv—B14—Mg2	143.77	H15c—Mg5—H7b^iii	95.92
H15c—B15—H15a	109.46	H15c—Mg5—H7a^iii	98.38
H15c—B15—H15b	109.48	H15c—Mg5—H9b	102.87
H15c—B15—H15d	109.48	H15c—Mg5—B7^iii	105.08
H15c—B15—Mg2^v	115.97	H15c—Mg5—B15	26.42
H15c—B15—Mg5	46.51	H15c—Mg5—B9	91.16
H15a—B15—H15b	109.47	H15c—Mg5—B13^vi	148.37
H15a—B15—H15d	109.47	H13c^vi—Mg5—H9d	73.21
H15a—B15—Mg2^v	67.50	H13c^vi—Mg5—H7b^iii	97.42
H15a—B15—Mg5	110.74	H13c^vi—Mg5—H7a^iii	95.67
H15b—B15—H15d	109.47	H13c^vi—Mg5—H9b	72.50
H15b—B15—Mg2^v	42.90	H13c^vi—Mg5—B7^iii	90.28
H15b—B15—Mg5	138.55	H13c^vi—Mg5—B15	142.08
H15d—B15—Mg2^v	132.62	H13c^vi—Mg5—B9	78.10
H15d—B15—Mg5	65.46	H13c^vi—Mg5—B13^vi	25.99
Mg2^v—B15—Mg5	161.88	H9d—Mg5—H7b^iii	131.32
H8b—Mg1—H14b^vi	81.54	H9d—Mg5—H7a^iii	167.78
H8b—Mg1—H12d^i	101.72	H9d—Mg5—H9b	53.00
H8b—Mg1—H8a	55.36	H9d—Mg5—B7^iii	152.56
H8b—Mg1—H12b^i	144.50	H9d—Mg5—B15	82.79
H8b—Mg1—H14d^vi	123.60	H9d—Mg5—B9	27.17
H8b—Mg1—H11c^vii	123.68	H9d—Mg5—B13^vi	79.83
H8b—Mg1—B8	29.48	H7b^iii—Mg5—H7a^iii	53.81
H8b—Mg1—B14^vi	99.32	H7b^iii—Mg5—H9b	78.43
H8b—Mg1—B11^vii	96.07	H7b^iii—Mg5—B7^iii	27.60
H8b—Mg1—B12^i	124.80	H7b^iii—Mg5—B15	120.39
H14b^vi—Mg1—H12d^i	173.57	H7b^iii—Mg5—B9	104.56
H14b^vi—Mg1—H8a	118.14	H7b^iii—Mg5—B13^vi	112.40
H14b^vi—Mg1—H12b^i	125.58	H7a^iii—Mg5—H9b	129.30
H14b^vi—Mg1—H14d^vi	53.91	H7a^iii—Mg5—B7^iii	27.91
H14b^vi—Mg1—H11c^vii	95.70	H7a^iii—Mg5—B15	104.11
H14b^vi—Mg1—B8	92.69	H7a^iii—Mg5—B9	156.97
H14b^vi—Mg1—B14^vi	27.43	H7a^iii—Mg5—B13^vi	87.95
H14b^vi—Mg1—B11^vii	93.46	H9b—Mg5—B7^iii	101.59
H14b^vi—Mg1—B12^i	152.26	H9b—Mg5—B15	115.19
H12d^i—Mg1—H8a	68.06	H9b—Mg5—B9	27.67
H12d^i—Mg1—H12b^i	54.03	H9b—Mg5—B13^vi	96.58
H12d^i—Mg1—H14d^vi	126.49	B7^iii—Mg5—B15	121.59
H12d^i—Mg1—H11c^vii	77.87	B7^iii—Mg5—B9	129.17
H12d^i—Mg1—B8	92.78	B7^iii—Mg5—B13^vi	94.98
H12d^i—Mg1—B14^vi	154.01	B15—Mg5—B9	93.76
H12d^i—Mg1—B11^vii	80.73	B15—Mg5—B13^vi	122.01
H12d^i—Mg1—B12^i	26.86	B9—Mg5—B13^vi	94.86
H8a—Mg1—H12b^i	89.60

Symmetry codes: (i) x−y, x−1, z+1/6; (ii) y+1, −x+y+2, z−1/6; (iii) y+1, −x+y+1, z−1/6; (iv) x, y+1, z; (v) x−y+2, x, z+1/6; (vi) x, y−1, z; (vii) x−y+1, x−1, z+1/6; (viii) y, −x+y+2, z−1/6.

(MgB2H8_HT) Magnesium borohydrides

Crystal data

MgB2H8	V = 7543.8 (5) Å^3
Mr = 53.99	Z = 64
Orthorhombic, Fddd	Synchrotron radiation, λ = 0.691246 Å
a = 37.072 (1) Å	µ = 1.30 mm^−1
b = 18.6476 (6) Å	T = 293 K
c = 10.9123 (3) Å	white

Data collection

Huber diffractometer	Data collection mode: transmission
Radiation source: synchrotron	Scan method: step
Si(111) channel cut monochromator	2θmin = 2.0°, 2θmax = 29.175°, 2θstep = 0.005°
Specimen mounting: capillary

Refinement

Rp = 0.025	82 parameters
Rwp = 0.031	H-atom parameters constrained
Rexp = 0.027	Weighting scheme based on measured s.u.'s 1/(sigma*sigma)
RBragg = 0.005	(Δ/σ)max < 0.001
5436 data points	Background function: Chebyshev polynomial with 34 coefficients
Excluded region(s): none	Preferred orientation correction: none
Profile function: Simple_Axial_model function with Rp=9999,Rs=330 in TOPAS-Academic

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

	x	y	z	Biso*/Beq
Mg1	0.07749 (12)	0.2501 (7)	0.5381 (6)	6.6 (2)
Mg2	0.05290 (11)	0.9298 (3)	0.7464 (13)	6.6 (2)
B3	0.4460 (6)	0.1533 (18)	0.410 (2)	10.1 (3)
B4	0.10777 (9)	1.0085 (3)	0.2636 (7)	10.1 (3)
B5	0.3124 (4)	0	0	10.1 (3)
B6	0.4441 (6)	0.6472 (17)	0.560 (2)	10.1 (3)
B7	0	0	0.773 (3)	10.1 (3)
H3a	0.428454	0.177826	0.352428	10.1 (3)
H3b	0.459357	0.190889	0.460083	10.1 (3)
H3c	0.463950	0.123907	0.361263	10.1 (3)
H3d	0.432119	0.120458	0.467946	10.1 (3)
H4a	0.122052	0.966240	0.230474	10.1 (3)
H4b	0.095066	0.993814	0.342209	10.1 (3)
H4c	0.089169	1.023987	0.200609	10.1 (3)
H4d	0.124793	1.049919	0.281228	10.1 (3)
H5a	0.328181	−0.044450	0.002788	10.1 (3)
H5c	0.296539	0.001631	0.075959	10.1 (3)
H6a	0.419913	0.672491	0.551912	10.1 (3)
H6b	0.440954	0.594258	0.540618	10.1 (3)
H6c	0.453297	0.652683	0.647313	10.1 (3)
H6d	0.462036	0.669209	0.500918	10.1 (3)
H7a	0.021809	0.009928	0.826708	10.1 (3)
H7c	0.004994	−0.043358	0.719212	10.1 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
?	?	?	?	?	?	?

Geometric parameters (Å, º)

H3a—B3	1.016	B4—Mg1	2.420
H3b—B3	1.016	B5—H5a	1.016
H3b—Mg1	1.950	B5—H5c	1.016
H3c—B3	1.016	B5—H5a^iii	1.016
H3c—Mg2	1.722	B5—H5c^iii	1.016
H3d—B3	1.016	B5—Mg1	2.380
H4a—B4	1.016	B5—Mg1^iii	2.380
H4a—Mg1	2.072	B6—H6b	1.016
H4b—B4	1.016	B6—H6c	1.016
H4c—B4	1.016	B6—H6a	1.016
H4c—Mg2^i	1.698	B6—H6d	1.016
H4d—B4	1.016	B6—Mg1	2.339
H4d—Mg1	2.000	B6—Mg2^ii	2.491
H5a—B5	1.016	B7—H7a	1.016
H5c—B5	1.016	B7—H7c	1.016
H5c—Mg1	1.876	B7—H7a^iv	1.016
H6a—B6	1.016	B7—H7c^iv	1.016
H6a—Mg1	1.751	B7—Mg2	2.375
H6b—B6	1.016	B7—Mg2^iv	2.375
H6c—B6	1.016	Mg1—H6a	1.751
H6c—Mg2^ii	1.895	Mg1—H5c	1.876
H6d—B6	1.016	Mg1—H3b	1.950
H6d—Mg1	2.145	Mg1—H4d	2.000
H7a—B7	1.016	Mg1—H4a	2.072
H7a—Mg2	2.080	Mg1—H6d	2.145
H7c—B7	1.016	Mg1—B6	2.339
H7c—Mg2	1.869	Mg1—B5	2.380
B3—H3c	1.016	Mg1—B4	2.420
B3—H3d	1.016	Mg1—B3	2.439
B3—H3a	1.016	Mg2—H4c^i	1.698
B3—H3b	1.016	Mg2—H3c	1.722
B3—Mg2	2.368	Mg2—H7c	1.869
B3—Mg1	2.439	Mg2—H6c^ii	1.895
B4—H4a	1.016	Mg2—H7a	2.080
B4—H4b	1.016	Mg2—B4^i	2.339
B4—H4c	1.016	Mg2—B3	2.368
B4—H4d	1.016	Mg2—B7	2.375
B4—Mg2^i	2.339	Mg2—B6^ii	2.491
B3—H3b—Mg1	106.28	H7c^iv—B7—Mg2^iv	48.76
B3—H3c—Mg2	117.39	Mg2—B7—Mg2^iv	166.00
B4—H4a—Mg1	97.26	H6a—Mg1—H5c	119.36
B4—H4c—Mg2^i	116.83	H6a—Mg1—H3b	105.09
B4—H4d—Mg1	101.70	H6a—Mg1—H4d	108.33
B5—H5c—Mg1	106.96	H6a—Mg1—H4a	61.88
B6—H6a—Mg1	112.67	H6a—Mg1—H6d	49.14
B6—H6c—Mg2^ii	114.27	H6a—Mg1—B6	23.63
B6—H6d—Mg1	87.84	H6a—Mg1—B5	123.89
B7—H7a—Mg2	93.84	H6a—Mg1—B4	86.41
B7—H7c—Mg2	107.11	H6a—Mg1—B3	108.06
H3c—B3—H3d	109.47	H5c—Mg1—H3b	84.71
H3c—B3—H3a	109.48	H5c—Mg1—H4d	124.28
H3c—B3—H3b	109.47	H5c—Mg1—H4a	142.85
H3c—B3—Mg2	40.22	H5c—Mg1—H6d	75.52
H3c—B3—Mg1	159.09	H5c—Mg1—B6	99.59
H3d—B3—H3a	109.47	H5c—Mg1—B5	24.10
H3d—B3—H3b	109.47	H5c—Mg1—B4	133.85
H3d—B3—Mg2	94.69	H5c—Mg1—B3	102.83
H3d—B3—Mg1	84.96	H3b—Mg1—H4d	109.92
H3a—B3—H3b	109.47	H3b—Mg1—H4a	132.22
H3a—B3—Mg2	80.53	H3b—Mg1—H6d	80.32
H3a—B3—Mg1	78.14	H3b—Mg1—B6	91.38
H3b—B3—Mg2	147.82	H3b—Mg1—B5	105.02
H3b—B3—Mg1	50.14	H3b—Mg1—B4	127.58
Mg2—B3—Mg1	157.21	H3b—Mg1—B3	23.57
H4a—B4—H4b	109.46	H4d—Mg1—H4a	48.05
H4a—B4—H4c	109.47	H4d—Mg1—H6d	157.47
H4a—B4—H4d	109.48	H4d—Mg1—B6	131.79
H4a—B4—Mg2^i	144.86	H4d—Mg1—B5	104.18
H4a—B4—Mg1	58.13	H4d—Mg1—B4	24.27
H4b—B4—H4c	109.48	H4d—Mg1—B3	87.16
H4b—B4—H4d	109.47	H4a—Mg1—H6d	110.05
H4b—B4—Mg2^i	76.65	H4a—Mg1—B6	85.38
H4b—B4—Mg1	110.43	H4a—Mg1—B5	120.50
H4c—B4—H4d	109.46	H4a—Mg1—B4	24.61
H4c—B4—Mg2^i	40.37	H4a—Mg1—B3	111.95
H4c—B4—Mg1	140.03	H6d—Mg1—B6	25.73
H4d—B4—Mg2^i	100.08	H6d—Mg1—B5	91.80
H4d—B4—Mg1	54.03	H6d—Mg1—B4	134.54
Mg2^i—B4—Mg1	154.09	H6d—Mg1—B3	99.36
H5a—B5—H5c	109.47	B6—Mg1—B5	111.39
H5a—B5—H5a^iii	109.47	B6—Mg1—B4	109.97
H5a—B5—H5c^iii	109.47	B6—Mg1—B3	102.88
H5a—B5—Mg1	80.51	B5—Mg1—B4	109.93
H5a—B5—Mg1^iii	83.84	B5—Mg1—B3	118.12
H5c—B5—H5a^iii	109.47	B4—Mg1—B3	104.04
H5c—B5—H5c^iii	109.47	H4c^i—Mg2—H3c	109.56
H5c—B5—Mg1	48.94	H4c^i—Mg2—H7c	132.14
H5c—B5—Mg1^iii	158.29	H4c^i—Mg2—H6c^ii	134.60
H5a^iii—B5—H5c^iii	109.47	H4c^i—Mg2—H7a	86.06
H5a^iii—B5—Mg1	83.84	H4c^i—Mg2—B4^i	22.80
H5a^iii—B5—Mg1^iii	80.51	H4c^i—Mg2—B3	93.48
H5c^iii—B5—Mg1	158.29	H4c^i—Mg2—B7	109.45
H5c^iii—B5—Mg1^iii	48.94	H4c^i—Mg2—B6^ii	122.28
Mg1—B5—Mg1^iii	152.73	H3c—Mg2—H7c	85.79
H6b—B6—H6c	109.47	H3c—Mg2—H6c^ii	84.19
H6b—B6—H6a	109.46	H3c—Mg2—H7a	84.86
H6b—B6—H6d	109.48	H3c—Mg2—B4^i	129.48
H6b—B6—Mg1	131.43	H3c—Mg2—B3	22.39
H6b—B6—Mg2^ii	67.47	H3c—Mg2—B7	86.12
H6c—B6—H6a	109.48	H3c—Mg2—B6^ii	105.95
H6c—B6—H6d	109.46	H7c—Mg2—H6c^ii	90.64
H6c—B6—Mg1	117.47	H7c—Mg2—H7a	49.33
H6c—B6—Mg2^ii	43.91	H7c—Mg2—B4^i	133.42
H6a—B6—H6d	109.48	H7c—Mg2—B3	108.18
H6a—B6—Mg1	43.69	H7c—Mg2—B7	24.13
H6a—B6—Mg2^ii	112.37	H7c—Mg2—B6^ii	93.88
H6d—B6—Mg1	66.43	H6c^ii—Mg2—H7a	139.14
H6d—B6—Mg2^ii	136.29	H6c^ii—Mg2—B4^i	118.55
Mg1—B6—Mg2^ii	149.60	H6c^ii—Mg2—B3	84.38
H7a—B7—H7c	109.48	H6c^ii—Mg2—B7	114.63
H7a—B7—H7a^iv	109.47	H6c^ii—Mg2—B6^ii	21.83
H7a—B7—H7c^iv	109.46	H7a—Mg2—B4^i	98.54
H7a—B7—Mg2	60.90	H7a—Mg2—B3	99.29
H7a—B7—Mg2^iv	128.83	H7a—Mg2—B7	25.26
H7c—B7—H7a^iv	109.46	H7a—Mg2—B6^ii	141.50
H7c—B7—H7c^iv	109.47	B4^i—Mg2—B3	109.99
H7c—B7—Mg2	48.76	B4^i—Mg2—B7	116.92
H7c—B7—Mg2^iv	121.23	B4^i—Mg2—B6^ii	101.87
H7a^iv—B7—H7c^iv	109.48	B3—Mg2—B7	106.44
H7a^iv—B7—Mg2	128.83	B3—Mg2—B6^ii	103.81
H7a^iv—B7—Mg2^iv	60.90	B7—Mg2—B6^ii	117.03
H7c^iv—B7—Mg2	121.23

Symmetry codes: (i) −x+3/4, −y+1/4, −z+3/4; (ii) x, −y+1/2, −z+1/2; (iii) x, −y+1/2, −z+3/2; (iv) −x+1, −y, z.