Niobium-bearing arsenides and germanides from elemental mixtures not involving niobium: a new twist to an old problem in solid-state synthesis

Three isostructural transition-metal arsenides and germanides, namely niobium nickel arsenide, Nb_0.92(1)NiAs, niobium cobalt arsenide, NbCoAs, and niobium nickel germanide, NbNiGe, were obtained as inadvertent side products of high-temperature reactions in sealed niobium containers. In addition to reporting for the very first time the structures of the title compounds, refined from single-crystal X-ray diffraction data, this article also serves as a reminder that niobium containers may not be suitable for the synthesis of ternary arsenides and germanides by traditional high-temperature reactions. Synthetic work involving alkali or alkaline-earth metals, transition or early post-transition metals, and elements from groups 14 or 15 under such conditions may yield Nb-containing products, which at times could be the major products of such reactions.

Computing details

For all structures, data collection: APEX2 (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018 (Sheldrick, 2015b); molecular graphics: CrystalMaker (Palmer, 2014); software used to prepare material for publication: publCIF (Westrip, 2010).

Niobium nickel arsenide (1)

Crystal data

Nb0.92(1)NiAs	Dx = 8.794 Mg m^−3
Mr = 219.11	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pnma	Cell parameters from 853 reflections
a = 6.2115 (19) Å	θ = 6.6–27.9°
b = 3.7150 (11) Å	µ = 36.98 mm^−1
c = 7.172 (2) Å	T = 200 K
V = 165.50 (9) Å^3	Irregular, black
Z = 4	0.04 × 0.03 × 0.03 mm
F(000) = 395

Data collection

Bruker SMART APEXII DUO CCD diffractometer	210 reflections with I > 2σ(I)
Radiation source: sealed tube	Rint = 0.097
phi and ω scans	θmax = 28.2°, θmin = 4.3°
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	h = −8→8
Tmin = 0.25, Tmax = 0.40	k = −4→4
2044 measured reflections	l = −9→9
238 independent reflections

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	w = 1/[σ^2(Fo^2)] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.019	(Δ/σ)max < 0.001
wR(F^2) = 0.038	Δρmax = 1.07 e Å^−3
S = 0.90	Δρmin = −1.42 e Å^−3
238 reflections	Extinction correction: SHELXL2018 (Sheldrick, 2015b), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
21 parameters	Extinction coefficient: 0.0175 (15)

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.

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

	x	y	z	Uiso*/Ueq	Occ. (<1)
Nb	0.02495 (8)	0.250000	0.66875 (9)	0.0082 (2)	0.916 (3)
Ni	0.14729 (12)	0.250000	0.06403 (10)	0.0082 (2)
As	0.27103 (9)	0.250000	0.37569 (8)	0.0092 (2)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Nb	0.0084 (3)	0.0086 (3)	0.0077 (3)	0.000	0.0006 (2)	0.000
Ni	0.0099 (4)	0.0078 (4)	0.0068 (4)	0.000	0.0007 (3)	0.000
As	0.0116 (3)	0.0075 (3)	0.0085 (3)	0.000	−0.0012 (2)	0.000

Geometric parameters (Å, º)

Nb—As	2.5988 (10)	Nb—Ni^v	2.8793 (11)
Nb—As^i	2.6328 (8)	Nb—Ni^vi	2.9350 (13)
Nb—As^ii	2.6328 (8)	Nb—Nb^i	3.0668 (12)
Nb—As^iii	2.6943 (8)	Ni—As^vii	2.3521 (8)
Nb—As^iv	2.6943 (8)	Ni—As^viii	2.3521 (8)
Nb—Ni^iii	2.8564 (9)	Ni—As	2.3637 (11)
Nb—Ni^iv	2.8564 (9)	Ni—As^v	2.3768 (12)
Nb—Ni^ii	2.8754 (9)	Ni—Ni^ix	2.7644 (12)
Nb—Ni^i	2.8754 (9)	Ni—Ni^x	2.7644 (12)
As—Nb—As^i	108.23 (3)	As^v—Ni—Nb^viii	130.77 (2)
As—Nb—As^ii	108.23 (3)	Ni^ix—Ni—Nb^viii	174.92 (5)
As^i—Nb—As^ii	89.74 (3)	Ni^x—Ni—Nb^viii	97.02 (3)
As—Nb—As^iii	99.72 (2)	As^vii—Ni—Nb^vii	58.91 (2)
As^i—Nb—As^iii	151.83 (3)	As^viii—Ni—Nb^vii	120.72 (4)
As^ii—Nb—As^iii	84.76 (2)	As—Ni—Nb^vii	61.29 (2)
As—Nb—As^iv	99.72 (2)	As^v—Ni—Nb^vii	130.77 (2)
As^i—Nb—As^iv	84.76 (2)	Ni^ix—Ni—Nb^vii	97.02 (3)
As^ii—Nb—As^iv	151.83 (3)	Ni^x—Ni—Nb^vii	174.92 (5)
As^iii—Nb—As^iv	87.17 (3)	Nb^viii—Ni—Nb^vii	81.13 (3)
As—Nb—Ni^iii	50.813 (18)	As^vii—Ni—Nb^ii	166.70 (3)
As^i—Nb—Ni^iii	157.62 (3)	As^viii—Ni—Nb^ii	87.30 (3)
As^ii—Nb—Ni^iii	90.41 (3)	As—Ni—Nb^ii	59.38 (3)
As^iii—Nb—Ni^iii	50.30 (2)	As^v—Ni—Nb^ii	60.85 (2)
As^iv—Nb—Ni^iii	104.95 (3)	Ni^ix—Ni—Nb^ii	114.16 (4)
As—Nb—Ni^iv	50.813 (19)	Ni^x—Ni—Nb^ii	62.68 (3)
As^i—Nb—Ni^iv	90.41 (3)	Nb^viii—Ni—Nb^ii	70.72 (2)
As^ii—Nb—Ni^iv	157.62 (3)	Nb^vii—Ni—Nb^ii	120.67 (3)
As^iii—Nb—Ni^iv	104.95 (3)	As^vii—Ni—Nb^i	87.30 (3)
As^iv—Nb—Ni^iv	50.30 (2)	As^viii—Ni—Nb^i	166.70 (3)
Ni^iii—Nb—Ni^iv	81.13 (3)	As—Ni—Nb^i	59.38 (3)
As—Nb—Ni^ii	139.278 (17)	As^v—Ni—Nb^i	60.85 (2)
As^i—Nb—Ni^ii	106.06 (3)	Ni^ix—Ni—Nb^i	62.68 (3)
As^ii—Nb—Ni^ii	50.59 (2)	Ni^x—Ni—Nb^i	114.16 (4)
As^iii—Nb—Ni^ii	50.39 (2)	Nb^viii—Ni—Nb^i	120.67 (3)
As^iv—Nb—Ni^ii	104.67 (3)	Nb^vii—Ni—Nb^i	70.72 (2)
Ni^iii—Nb—Ni^ii	91.17 (2)	Nb^ii—Ni—Nb^i	80.48 (3)
Ni^iv—Nb—Ni^ii	149.38 (3)	As^vii—Ni—Nb^xi	59.42 (2)
As—Nb—Ni^i	139.278 (16)	As^viii—Ni—Nb^xi	59.42 (2)
As^i—Nb—Ni^i	50.59 (2)	As—Ni—Nb^xi	106.46 (4)
As^ii—Nb—Ni^i	106.06 (3)	As^v—Ni—Nb^xi	155.04 (4)
As^iii—Nb—Ni^i	104.67 (3)	Ni^ix—Ni—Nb^xi	110.28 (4)
As^iv—Nb—Ni^i	50.39 (2)	Ni^x—Ni—Nb^xi	110.28 (4)
Ni^iii—Nb—Ni^i	149.38 (3)	Nb^viii—Ni—Nb^xi	64.64 (3)
Ni^iv—Nb—Ni^i	91.17 (2)	Nb^vii—Ni—Nb^xi	64.64 (3)
Ni^ii—Nb—Ni^i	80.48 (3)	Nb^ii—Ni—Nb^xi	133.599 (19)
As—Nb—Ni^v	90.59 (3)	Nb^i—Ni—Nb^xi	133.599 (19)
As^i—Nb—Ni^v	50.274 (18)	As^vii—Ni—Nb^xii	60.08 (2)
As^ii—Nb—Ni^v	50.274 (18)	As^viii—Ni—Nb^xii	60.08 (2)
As^iii—Nb—Ni^v	134.638 (16)	As—Ni—Nb^xii	176.03 (4)
As^iv—Nb—Ni^v	134.638 (16)	As^v—Ni—Nb^xii	85.47 (3)
Ni^iii—Nb—Ni^v	115.36 (3)	Ni^ix—Ni—Nb^xii	60.51 (3)
Ni^iv—Nb—Ni^v	115.36 (3)	Ni^x—Ni—Nb^xii	60.51 (3)
Ni^ii—Nb—Ni^v	94.78 (2)	Nb^viii—Ni—Nb^xii	116.01 (3)
Ni^i—Nb—Ni^v	94.78 (2)	Nb^vii—Ni—Nb^xii	116.01 (3)
As—Nb—Ni^vi	128.97 (3)	Nb^ii—Ni—Nb^xii	123.19 (3)
As^i—Nb—Ni^vi	107.32 (2)	Nb^i—Ni—Nb^xii	123.19 (3)
As^ii—Nb—Ni^vi	107.32 (2)	Nb^xi—Ni—Nb^xii	69.57 (3)
As^iii—Nb—Ni^vi	49.166 (18)	Ni^iii—As—Ni^iv	104.32 (4)
As^iv—Nb—Ni^vi	49.166 (18)	Ni^iii—As—Ni	127.82 (2)
Ni^iii—Nb—Ni^vi	93.98 (2)	Ni^iv—As—Ni	127.82 (2)
Ni^iv—Nb—Ni^vi	93.98 (2)	Ni^iii—As—Ni^xi	71.54 (3)
Ni^ii—Nb—Ni^vi	56.81 (3)	Ni^iv—As—Ni^xi	71.54 (3)
Ni^i—Nb—Ni^vi	56.81 (3)	Ni—As—Ni^xi	119.46 (3)
Ni^v—Nb—Ni^vi	140.44 (3)	Ni^iii—As—Nb	70.27 (3)
As—Nb—Nb^i	54.63 (2)	Ni^iv—As—Nb	70.27 (3)
As^i—Nb—Nb^i	53.598 (19)	Ni—As—Nb	125.00 (4)
As^ii—Nb—Nb^i	105.14 (3)	Ni^xi—As—Nb	115.55 (4)
As^iii—Nb—Nb^i	154.14 (3)	Ni^iii—As—Nb^i	141.02 (3)
As^iv—Nb—Nb^i	93.71 (2)	Ni^iv—As—Nb^i	70.31 (3)
Ni^iii—Nb—Nb^i	104.97 (3)	Ni—As—Nb^i	70.03 (2)
Ni^iv—Nb—Nb^i	58.04 (2)	Ni^xi—As—Nb^i	135.126 (17)
Ni^ii—Nb—Nb^i	151.61 (3)	Nb—As—Nb^i	71.77 (3)
Ni^i—Nb—Nb^i	95.58 (3)	Ni^iii—As—Nb^ii	70.31 (3)
Ni^v—Nb—Nb^i	57.32 (2)	Ni^iv—As—Nb^ii	141.02 (3)
Ni^vi—Nb—Nb^i	142.047 (19)	Ni—As—Nb^ii	70.03 (2)
As^vii—Ni—As^viii	104.32 (4)	Ni^xi—As—Nb^ii	135.126 (17)
As^vii—Ni—As	118.22 (2)	Nb—As—Nb^ii	71.77 (3)
As^viii—Ni—As	118.22 (2)	Nb^i—As—Nb^ii	89.74 (3)
As^vii—Ni—As^v	108.46 (3)	Ni^iii—As—Nb^vii	139.41 (3)
As^viii—Ni—As^v	108.46 (3)	Ni^iv—As—Nb^vii	70.76 (3)
As—Ni—As^v	98.50 (3)	Ni—As—Nb^vii	68.41 (3)
As^vii—Ni—Ni^ix	54.64 (3)	Ni^xi—As—Nb^vii	68.76 (2)
As^viii—Ni—Ni^ix	118.86 (5)	Nb—As—Nb^vii	136.233 (16)
As—Ni—Ni^ix	121.96 (4)	Nb^i—As—Nb^vii	77.02 (2)
As^v—Ni—Ni^ix	53.81 (3)	Nb^ii—As—Nb^vii	138.43 (3)
As^vii—Ni—Ni^x	118.86 (5)	Ni^iii—As—Nb^viii	70.76 (3)
As^viii—Ni—Ni^x	54.64 (3)	Ni^iv—As—Nb^viii	139.41 (3)
As—Ni—Ni^x	121.96 (4)	Ni—As—Nb^viii	68.41 (3)
As^v—Ni—Ni^x	53.81 (3)	Ni^xi—As—Nb^viii	68.76 (2)
Ni^ix—Ni—Ni^x	84.43 (5)	Nb—As—Nb^viii	136.233 (16)
As^vii—Ni—Nb^viii	120.72 (4)	Nb^i—As—Nb^viii	138.43 (3)
As^viii—Ni—Nb^viii	58.91 (2)	Nb^ii—As—Nb^viii	77.02 (2)
As—Ni—Nb^viii	61.29 (2)	Nb^vii—As—Nb^viii	87.17 (3)

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

Niobium cobalt arsenide (2)

Crystal data

NbCoAs	Dx = 9.009 Mg m^−3
Mr = 226.76	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pnma	Cell parameters from 1020 reflections
a = 6.2656 (15) Å	θ = 3.3–28.1°
b = 3.7273 (9) Å	µ = 35.79 mm^−1
c = 7.1589 (17) Å	T = 200 K
V = 167.19 (7) Å^3	Irregular, black
Z = 4	0.05 × 0.04 × 0.04 mm
F(000) = 404

Data collection

Bruker SMART APEXII DUO CCD diffractometer	235 reflections with I > 2σ(I)
Radiation source: sealed tube	Rint = 0.104
phi and ω scans	θmax = 28.3°, θmin = 4.3°
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	h = −8→8
Tmin = 0.138, Tmax = 0.241	k = −4→4
1902 measured reflections	l = −9→9
240 independent reflections

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	w = 1/[σ^2(Fo^2) + (0.0154P)^2 + 0.713P] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.021	(Δ/σ)max < 0.001
wR(F^2) = 0.051	Δρmax = 0.94 e Å^−3
S = 1.05	Δρmin = −1.11 e Å^−3
240 reflections	Extinction correction: SHELXL2018 (Sheldrick, 2015b), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
20 parameters	Extinction coefficient: 0.0139 (18)

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.

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

	x	y	z	Uiso*/Ueq
Nb	0.02493 (9)	0.250000	0.67299 (7)	0.0045 (2)
Co	0.14738 (14)	0.250000	0.06272 (11)	0.0047 (3)
As	0.27439 (10)	0.250000	0.37711 (9)	0.0042 (2)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Nb	0.0045 (3)	0.0044 (3)	0.0047 (3)	0.000	−0.00024 (18)	0.000
Co	0.0055 (5)	0.0039 (5)	0.0046 (4)	0.000	0.0005 (3)	0.000
As	0.0048 (4)	0.0029 (4)	0.0049 (3)	0.000	0.0001 (2)	0.000

Geometric parameters (Å, º)

Nb—As	2.6324 (9)	Nb—Co^v	2.8936 (11)
Nb—As^i	2.6682 (8)	Nb—Co^vi	2.9058 (12)
Nb—As^ii	2.6682 (8)	Nb—Nb^i	3.1154 (10)
Nb—As^iii	2.6813 (7)	Co—As^vii	2.3407 (7)
Nb—As^iv	2.6813 (7)	Co—As^viii	2.3407 (7)
Nb—Co^ii	2.8668 (9)	Co—As^vi	2.3763 (12)
Nb—Co^i	2.8668 (9)	Co—As	2.3873 (11)
Nb—Co^iii	2.8830 (9)	Co—Co^ix	2.7732 (14)
Nb—Co^iv	2.8830 (9)	Co—Co^x	2.7731 (14)
As—Nb—As^i	108.01 (2)	As—Co—Nb^ii	60.22 (2)
As—Nb—As^ii	108.01 (2)	Co^ix—Co—Nb^ii	113.57 (5)
As^i—Nb—As^ii	88.61 (3)	Co^x—Co—Nb^ii	61.71 (3)
As—Nb—As^iii	99.21 (2)	As^vii—Co—Nb^i	86.33 (2)
As^i—Nb—As^iii	152.67 (3)	As^viii—Co—Nb^i	166.19 (3)
As^ii—Nb—As^iii	85.26 (2)	As^vi—Co—Nb^i	60.66 (2)
As—Nb—As^iv	99.21 (2)	As—Co—Nb^i	60.22 (2)
As^i—Nb—As^iv	85.26 (2)	Co^ix—Co—Nb^i	61.71 (3)
As^ii—Nb—As^iv	152.67 (3)	Co^x—Co—Nb^i	113.57 (5)
As^iii—Nb—As^iv	88.06 (3)	Nb^ii—Co—Nb^i	81.10 (3)
As—Nb—Co^ii	138.995 (16)	As^vii—Co—Nb^viii	121.40 (4)
As^i—Nb—Co^ii	106.15 (3)	As^viii—Co—Nb^viii	59.44 (2)
As^ii—Nb—Co^ii	50.95 (2)	As^vi—Co—Nb^viii	130.60 (3)
As^iii—Nb—Co^ii	50.59 (3)	As—Co—Nb^viii	60.29 (2)
As^iv—Nb—Co^ii	105.59 (3)	Co^ix—Co—Nb^viii	175.83 (5)
As—Nb—Co^i	138.995 (16)	Co^x—Co—Nb^viii	97.38 (2)
As^i—Nb—Co^i	50.95 (2)	Nb^ii—Co—Nb^viii	70.565 (19)
As^ii—Nb—Co^i	106.15 (3)	Nb^i—Co—Nb^viii	120.51 (3)
As^iii—Nb—Co^i	105.59 (3)	As^vii—Co—Nb^vii	59.44 (2)
As^iv—Nb—Co^i	50.59 (3)	As^viii—Co—Nb^vii	121.40 (4)
Co^ii—Nb—Co^i	81.10 (3)	As^vi—Co—Nb^vii	130.60 (3)
As—Nb—Co^iii	49.971 (19)	As—Co—Nb^vii	60.29 (2)
As^i—Nb—Co^iii	156.24 (3)	Co^ix—Co—Nb^vii	97.38 (2)
As^ii—Nb—Co^iii	90.70 (3)	Co^x—Co—Nb^vii	175.83 (5)
As^iii—Nb—Co^iii	50.65 (2)	Nb^ii—Co—Nb^vii	120.51 (3)
As^iv—Nb—Co^iii	105.34 (3)	Nb^i—Co—Nb^vii	70.565 (19)
Co^ii—Nb—Co^iii	91.64 (2)	Nb^viii—Co—Nb^vii	80.54 (3)
Co^i—Nb—Co^iii	150.36 (3)	As^vii—Co—Nb^xi	60.54 (2)
As—Nb—Co^iv	49.971 (19)	As^viii—Co—Nb^xi	60.54 (2)
As^i—Nb—Co^iv	90.70 (3)	As^vi—Co—Nb^xi	85.07 (4)
As^ii—Nb—Co^iv	156.24 (3)	As—Co—Nb^xi	175.90 (5)
As^iii—Nb—Co^iv	105.34 (3)	Co^ix—Co—Nb^xi	60.74 (3)
As^iv—Nb—Co^iv	50.65 (2)	Co^x—Co—Nb^xi	60.74 (3)
Co^ii—Nb—Co^iv	150.36 (3)	Nb^ii—Co—Nb^xi	122.45 (3)
Co^i—Nb—Co^iv	91.64 (2)	Nb^i—Co—Nb^xi	122.45 (3)
Co^iii—Nb—Co^iv	80.54 (3)	Nb^viii—Co—Nb^xi	116.93 (3)
As—Nb—Co^v	128.20 (4)	Nb^vii—Co—Nb^xi	116.93 (3)
As^i—Nb—Co^v	108.42 (2)	As^vii—Co—Nb^xii	59.99 (2)
As^ii—Nb—Co^v	108.42 (2)	As^viii—Co—Nb^xii	59.99 (2)
As^iii—Nb—Co^v	49.473 (17)	As^vi—Co—Nb^xii	154.94 (4)
As^iv—Nb—Co^v	49.473 (17)	As—Co—Nb^xii	106.03 (4)
Co^ii—Nb—Co^v	57.55 (3)	Co^ix—Co—Nb^xii	110.74 (4)
Co^i—Nb—Co^v	57.55 (3)	Co^x—Co—Nb^xii	110.74 (4)
Co^iii—Nb—Co^v	94.31 (2)	Nb^ii—Co—Nb^xii	133.62 (2)
Co^iv—Nb—Co^v	94.31 (2)	Nb^i—Co—Nb^xii	133.62 (2)
As—Nb—Co^vi	90.92 (3)	Nb^viii—Co—Nb^xii	65.12 (3)
As^i—Nb—Co^vi	49.436 (18)	Nb^vii—Co—Nb^xii	65.12 (3)
As^ii—Nb—Co^vi	49.436 (18)	Nb^xi—Co—Nb^xii	69.87 (2)
As^iii—Nb—Co^vi	134.286 (17)	Co^iii—As—Co^iv	105.53 (4)
As^iv—Nb—Co^vi	134.286 (17)	Co^iii—As—Co^xii	72.01 (3)
Co^ii—Nb—Co^vi	94.40 (2)	Co^iv—As—Co^xii	72.01 (3)
Co^i—Nb—Co^vi	94.40 (2)	Co^iii—As—Co	127.23 (2)
Co^iii—Nb—Co^vi	114.88 (3)	Co^iv—As—Co	127.23 (2)
Co^iv—Nb—Co^vi	114.88 (3)	Co^xii—As—Co	119.92 (4)
Co^v—Nb—Co^vi	140.88 (4)	Co^iii—As—Nb	70.58 (3)
As—Nb—Nb^i	54.54 (2)	Co^iv—As—Nb	70.58 (3)
As^i—Nb—Nb^i	53.47 (2)	Co^xii—As—Nb	115.98 (4)
As^ii—Nb—Nb^i	103.91 (3)	Co—As—Nb	124.10 (4)
As^iii—Nb—Nb^i	153.65 (3)	Co^iii—As—Nb^i	141.22 (3)
As^iv—Nb—Nb^i	93.70 (2)	Co^iv—As—Nb^i	70.57 (3)
Co^ii—Nb—Nb^i	151.14 (4)	Co^xii—As—Nb^i	135.695 (16)
Co^i—Nb—Nb^i	95.63 (2)	Co—As—Nb^i	68.83 (2)
Co^iii—Nb—Nb^i	103.91 (3)	Nb—As—Nb^i	71.99 (2)
Co^iv—Nb—Nb^i	57.79 (2)	Co^iii—As—Nb^ii	70.57 (3)
Co^v—Nb—Nb^i	142.484 (17)	Co^iv—As—Nb^ii	141.22 (3)
Co^vi—Nb—Nb^i	57.09 (2)	Co^xii—As—Nb^ii	135.695 (16)
As^vii—Co—As^viii	105.53 (4)	Co—As—Nb^ii	68.83 (2)
As^vii—Co—As^vi	107.99 (3)	Nb—As—Nb^ii	71.99 (2)
As^viii—Co—As^vi	107.99 (3)	Nb^i—As—Nb^ii	88.61 (3)
As^vii—Co—As	117.73 (3)	Co^iii—As—Nb^vii	139.87 (4)
As^viii—Co—As	117.73 (3)	Co^iv—As—Nb^vii	69.99 (3)
As^vi—Co—As	99.03 (4)	Co^xii—As—Nb^vii	68.75 (2)
As^vii—Co—Co^ix	54.59 (3)	Co—As—Nb^vii	69.05 (3)
As^viii—Co—Co^ix	119.39 (5)	Nb—As—Nb^vii	135.803 (15)
As^vi—Co—Co^ix	53.40 (3)	Nb^i—As—Nb^vii	76.754 (19)
As—Co—Co^ix	121.82 (4)	Nb^ii—As—Nb^vii	137.89 (3)
As^vii—Co—Co^x	119.39 (5)	Co^iii—As—Nb^viii	69.99 (3)
As^viii—Co—Co^x	54.59 (3)	Co^iv—As—Nb^viii	139.87 (4)
As^vi—Co—Co^x	53.40 (3)	Co^xii—As—Nb^viii	68.75 (2)
As—Co—Co^x	121.82 (4)	Co—As—Nb^viii	69.05 (3)
Co^ix—Co—Co^x	84.45 (5)	Nb—As—Nb^viii	135.803 (15)
As^vii—Co—Nb^ii	166.19 (3)	Nb^i—As—Nb^viii	137.89 (3)
As^viii—Co—Nb^ii	86.33 (2)	Nb^ii—As—Nb^viii	76.754 (19)
As^vi—Co—Nb^ii	60.66 (2)	Nb^vii—As—Nb^viii	88.06 (3)

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

Niobium nickel germanide (3)

Crystal data

NbNiGe	Dx = 8.726 Mg m^−3
Mr = 224.21	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pnma	Cell parameters from 791 reflections
a = 6.2989 (8) Å	θ = 6.5–27.5°
b = 3.7613 (4) Å	µ = 34.41 mm^−1
c = 7.2033 (8) Å	T = 200 K
V = 170.66 (3) Å^3	Needle, silver
Z = 4	0.07 × 0.03 × 0.02 mm
F(000) = 404

Data collection

Bruker SMART APEXII DUO CCD diffractometer	230 reflections with I > 2σ(I)
Radiation source: sealed tube	Rint = 0.036
phi and ω scans	θmax = 28.1°, θmin = 4.3°
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	h = −8→7
Tmin = 0.19, Tmax = 0.50	k = −5→5
1826 measured reflections	l = −9→9
240 independent reflections

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	w = 1/[σ^2(Fo^2) + (0.0303P)^2] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.023	(Δ/σ)max < 0.001
wR(F^2) = 0.059	Δρmax = 1.29 e Å^−3
S = 1.33	Δρmin = −2.25 e Å^−3
240 reflections	Extinction correction: SHELXL2018 (Sheldrick, 2015b), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
20 parameters	Extinction coefficient: 0.038 (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.

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

	x	y	z	Uiso*/Ueq
Nb	0.01789 (10)	0.250000	0.67656 (9)	0.0052 (3)
Ni	0.15738 (15)	0.250000	0.06922 (13)	0.0069 (3)
Ge	0.27997 (12)	0.250000	0.38311 (11)	0.0057 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Nb	0.0047 (4)	0.0068 (4)	0.0041 (4)	0.000	−0.0003 (2)	0.000
Ni	0.0069 (6)	0.0081 (5)	0.0058 (5)	0.000	0.0011 (4)	0.000
Ge	0.0056 (5)	0.0067 (4)	0.0047 (4)	0.000	0.0008 (3)	0.000

Geometric parameters (Å, º)

Nb—Ge	2.6820 (10)	Nb—Ni^iv	2.8842 (8)
Nb—Ge^i	2.6910 (7)	Nb—Ni^vi	2.9618 (12)
Nb—Ge^ii	2.6910 (7)	Nb—Nb^i	3.1714 (10)
Nb—Ge^iii	2.7151 (7)	Ni—Ge^vii	2.3430 (7)
Nb—Ge^iv	2.7151 (7)	Ni—Ge^viii	2.3430 (7)
Nb—Ni^ii	2.8476 (9)	Ni—Ge	2.3893 (12)
Nb—Ni^i	2.8476 (9)	Ni—Ge^v	2.4019 (12)
Nb—Ni^v	2.8794 (12)	Ni—Ni^ix	2.9090 (15)
Nb—Ni^iii	2.8842 (9)	Ni—Ni^x	2.9090 (15)
Ge—Nb—Ge^i	107.65 (3)	Ge^v—Ni—Nb^xi	150.28 (5)
Ge—Nb—Ge^ii	107.65 (3)	Nb^ii—Ni—Nb^xi	134.519 (19)
Ge^i—Nb—Ge^ii	88.67 (3)	Nb^i—Ni—Nb^xi	134.519 (19)
Ge—Nb—Ge^iii	98.236 (18)	Ge^vii—Ni—Nb^viii	123.87 (4)
Ge^i—Nb—Ge^iii	153.97 (3)	Ge^viii—Ni—Nb^viii	60.70 (2)
Ge^ii—Nb—Ge^iii	86.009 (16)	Ge—Ni—Nb^viii	61.13 (2)
Ge—Nb—Ge^iv	98.236 (18)	Ge^v—Ni—Nb^viii	131.57 (3)
Ge^i—Nb—Ge^iv	86.009 (16)	Nb^ii—Ni—Nb^viii	70.848 (16)
Ge^ii—Nb—Ge^iv	153.97 (3)	Nb^i—Ni—Nb^viii	122.22 (3)
Ge^iii—Nb—Ge^iv	87.68 (3)	Nb^xi—Ni—Nb^viii	66.77 (3)
Ge—Nb—Ni^ii	138.198 (16)	Ge^vii—Ni—Nb^vii	60.70 (2)
Ge^i—Nb—Ni^ii	107.09 (3)	Ge^viii—Ni—Nb^vii	123.87 (4)
Ge^ii—Nb—Ni^ii	51.01 (2)	Ge—Ni—Nb^vii	61.13 (2)
Ge^iii—Nb—Ni^ii	51.09 (2)	Ge^v—Ni—Nb^vii	131.57 (3)
Ge^iv—Nb—Ni^ii	106.67 (3)	Nb^ii—Ni—Nb^vii	122.22 (3)
Ge—Nb—Ni^i	138.198 (16)	Nb^i—Ni—Nb^vii	70.848 (17)
Ge^i—Nb—Ni^i	51.01 (2)	Nb^xi—Ni—Nb^vii	66.77 (3)
Ge^ii—Nb—Ni^i	107.09 (3)	Nb^viii—Ni—Nb^vii	81.39 (3)
Ge^iii—Nb—Ni^i	106.67 (3)	Ge^vii—Ni—Ni^ix	53.11 (3)
Ge^iv—Nb—Ni^i	51.09 (2)	Ge^viii—Ni—Ni^ix	115.95 (5)
Ni^ii—Nb—Ni^i	82.66 (3)	Ge—Ni—Ni^ix	123.00 (4)
Ge—Nb—Ni^v	90.05 (3)	Ge^v—Ni—Ni^ix	51.28 (3)
Ge^i—Nb—Ni^v	49.606 (18)	Nb^ii—Ni—Ni^ix	112.53 (5)
Ge^ii—Nb—Ni^v	49.606 (18)	Nb^i—Ni—Ni^ix	61.92 (3)
Ge^iii—Nb—Ni^v	134.973 (16)	Nb^xi—Ni—Ni^ix	109.07 (4)
Ge^iv—Nb—Ni^v	134.973 (16)	Nb^viii—Ni—Ni^ix	175.42 (6)
Ni^ii—Nb—Ni^v	95.143 (18)	Nb^vii—Ni—Ni^ix	98.842 (18)
Ni^i—Nb—Ni^v	95.143 (18)	Ge^vii—Ni—Ni^x	115.95 (5)
Ge—Nb—Ni^iii	49.625 (19)	Ge^viii—Ni—Ni^x	53.11 (3)
Ge^i—Nb—Ni^iii	155.14 (3)	Ge—Ni—Ni^x	123.00 (4)
Ge^ii—Nb—Ni^iii	89.77 (2)	Ge^v—Ni—Ni^x	51.28 (3)
Ge^iii—Nb—Ni^iii	50.41 (2)	Nb^ii—Ni—Ni^x	61.92 (3)
Ge^iv—Nb—Ni^iii	105.43 (3)	Nb^i—Ni—Ni^x	112.53 (5)
Ni^ii—Nb—Ni^iii	90.96 (2)	Nb^xi—Ni—Ni^x	109.07 (4)
Ni^i—Nb—Ni^iii	151.40 (3)	Nb^viii—Ni—Ni^x	98.842 (18)
Ni^v—Nb—Ni^iii	113.23 (3)	Nb^vii—Ni—Ni^x	175.42 (6)
Ge—Nb—Ni^iv	49.625 (19)	Ni^ix—Ni—Ni^x	80.56 (5)
Ge^i—Nb—Ni^iv	89.77 (2)	Ge^vii—Ni—Nb^xii	60.23 (3)
Ge^ii—Nb—Ni^iv	155.14 (3)	Ge^viii—Ni—Nb^xii	60.23 (3)
Ge^iii—Nb—Ni^iv	105.43 (3)	Ge—Ni—Nb^xii	178.40 (5)
Ge^iv—Nb—Ni^iv	50.41 (2)	Ge^v—Ni—Nb^xii	80.96 (4)
Ni^ii—Nb—Ni^iv	151.40 (3)	Nb^ii—Ni—Nb^xii	119.94 (3)
Ni^i—Nb—Ni^iv	90.96 (2)	Nb^i—Ni—Nb^xii	119.94 (3)
Ni^v—Nb—Ni^iv	113.23 (3)	Nb^xi—Ni—Nb^xii	69.32 (2)
Ni^iii—Nb—Ni^iv	81.39 (3)	Nb^viii—Ni—Nb^xii	117.80 (3)
Ge—Nb—Ni^vi	124.76 (4)	Nb^vii—Ni—Nb^xii	117.80 (3)
Ge^i—Nb—Ni^vi	111.06 (3)	Ni^ix—Ni—Nb^xii	58.02 (3)
Ge^ii—Nb—Ni^vi	111.06 (3)	Ni^x—Ni—Nb^xii	58.02 (3)
Ge^iii—Nb—Ni^vi	48.514 (19)	Ni^iii—Ge—Ni^iv	106.77 (5)
Ge^iv—Nb—Ni^vi	48.514 (19)	Ni^iii—Ge—Ni	126.58 (2)
Ni^ii—Nb—Ni^vi	60.06 (3)	Ni^iv—Ge—Ni	126.58 (2)
Ni^i—Nb—Ni^vi	60.06 (3)	Ni^iii—Ge—Ni^xi	75.61 (4)
Ni^v—Nb—Ni^vi	145.20 (4)	Ni^iv—Ge—Ni^xi	75.61 (4)
Ni^iii—Nb—Ni^vi	92.62 (2)	Ni—Ge—Ni^xi	117.07 (4)
Ni^iv—Nb—Ni^vi	92.62 (2)	Ni^iii—Ge—Nb	69.68 (3)
Ge—Nb—Nb^i	53.96 (2)	Ni^iv—Ge—Nb	69.68 (3)
Ge^i—Nb—Nb^i	53.69 (2)	Ni—Ge—Nb	123.16 (4)
Ge^ii—Nb—Nb^i	103.70 (3)	Ni^xi—Ge—Nb	119.77 (4)
Ge^iii—Nb—Nb^i	152.08 (4)	Ni^iii—Ge—Nb^i	140.33 (4)
Ge^iv—Nb—Nb^i	93.560 (17)	Ni^iv—Ge—Nb^i	69.38 (3)
Ni^ii—Nb—Nb^i	151.62 (4)	Ni—Ge—Nb^i	67.88 (3)
Ni^i—Nb—Nb^i	95.542 (19)	Ni^xi—Ge—Nb^i	135.469 (14)
Ni^v—Nb—Nb^i	56.69 (2)	Nb—Ge—Nb^i	72.35 (3)
Ni^iii—Nb—Nb^i	102.83 (3)	Ni^iii—Ge—Nb^ii	69.38 (3)
Ni^iv—Nb—Nb^i	56.54 (2)	Ni^iv—Ge—Nb^ii	140.33 (4)
Ni^vi—Nb—Nb^i	141.909 (18)	Ni—Ge—Nb^ii	67.88 (3)
Ge^vii—Ni—Ge^viii	106.77 (5)	Ni^xi—Ge—Nb^ii	135.469 (15)
Ge^vii—Ni—Ge	119.15 (3)	Nb—Ge—Nb^ii	72.35 (3)
Ge^viii—Ni—Ge	119.15 (3)	Nb^i—Ge—Nb^ii	88.67 (3)
Ge^vii—Ni—Ge^v	104.39 (4)	Ni^iii—Ge—Nb^vii	142.23 (4)
Ge^viii—Ni—Ge^v	104.39 (4)	Ni^iv—Ge—Nb^vii	71.25 (3)
Ge—Ni—Ge^v	100.64 (4)	Ni—Ge—Nb^vii	68.47 (3)
Ge^vii—Ni—Nb^ii	164.44 (4)	Ni^xi—Ge—Nb^vii	67.31 (2)
Ge^viii—Ni—Nb^ii	84.44 (2)	Nb—Ge—Nb^vii	136.099 (15)
Ge—Ni—Nb^ii	61.10 (3)	Nb^i—Ge—Nb^vii	75.839 (14)
Ge^v—Ni—Nb^ii	61.60 (2)	Nb^ii—Ge—Nb^vii	136.34 (3)
Ge^vii—Ni—Nb^i	84.44 (2)	Ni^iii—Ge—Nb^viii	71.25 (3)
Ge^viii—Ni—Nb^i	164.44 (4)	Ni^iv—Ge—Nb^viii	142.23 (4)
Ge—Ni—Nb^i	61.10 (3)	Ni—Ge—Nb^viii	68.47 (3)
Ge^v—Ni—Nb^i	61.60 (2)	Ni^xi—Ge—Nb^viii	67.31 (2)
Nb^ii—Ni—Nb^i	82.66 (3)	Nb—Ge—Nb^viii	136.099 (15)
Ge^vii—Ni—Nb^xi	61.01 (3)	Nb^i—Ge—Nb^viii	136.34 (3)
Ge^viii—Ni—Nb^xi	61.01 (3)	Nb^ii—Ge—Nb^viii	75.839 (14)
Ge—Ni—Nb^xi	109.09 (4)	Nb^vii—Ge—Nb^viii	87.68 (3)

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

Unit-cell parameters for (1), (2), and (3), compared with the literature data
The small discrepancies between the published and the herein reported unit-cell parameters are likely due to the accuracy of the measurements, and/or the different temperature at which the experiments were conducted (literature data are at room temperature, while this work is carried out at 200 K).

Formula	a (Å)	b (Å)	c (Å)
NbCoAs (Rundqvist et al., 1967)	6.247	3.724	7.136
NbCoAs (this work)	6.2656 (15)	3.7273 (9)	7.1589 (17)
NbNiAs (Rundqvist et al., 1967)	6.242	3.721	7.19
Nb0.92 (1)NiAs (this work)	6.2115 (19)	3.7150 (11)	7.172 (2)
NbNiGe (Jeitschko et al., 1969)	6.300 (3)	3.770 (1)	7.196 (3)
NbNiGe (this work)	6.2989 (8)	3.7613 (4)	7.2033 (8)