Synthesis of FeN₄ at 180 GPa and its crystal structure from a submicron-sized grain

The refined crystal structure model of iron tetra­nitride, FeN₄, at 180 GPa is similar to that at 135 GPa but shows improved structural parameters in terms of bond lengths and angles.

Key indicators

• Single-crystal synchrotron study
• T = 293 K
• Mean [sigma](N-N) = 0.018 Å
• R factor = 0.040
• wR factor = 0.082
• Data-to-parameter ratio = 7.1

checkCIF/PLATON results

No syntax errors found



Alert level A
ATOM007_ALERT_1_A  _atom_site_aniso_label is missing
            Unique label identifying the atom site.

Author Response: Due to the limited dataset we had to perform an isotropic refinement.

PLAT029_ALERT_3_A _diffrn_measured_fraction_theta_full value Low .      0.341 Why?

Author Response: The dataset was collected while the sample was inside a diamond anvil cell. Incompleteness of the dataset was unavoidable.

Alert level B
PLAT088_ALERT_3_B Poor Data / Parameter Ratio ....................       7.10 Note
PLAT911_ALERT_3_B Missing FCF Refl Between Thmin & STh/L=    0.600         59 Report

Alert level C
PLAT155_ALERT_4_C The Triclinic Unitcell is NOT Reduced ..........     Please Do !
PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd.  #          1 Note
              Fe N4
PLAT913_ALERT_3_C Missing # of Very Strong Reflections in FCF ....          4 Note

Alert level G
ABSMU01_ALERT_1_G  Calculation of _exptl_absorpt_correction_mu
                not performed for this radiation type.
PLAT004_ALERT_5_G Polymeric Structure Found with Maximum Dimension          3 Info
PLAT199_ALERT_1_G Reported _cell_measurement_temperature ..... (K)        293 Check
PLAT200_ALERT_1_G Reported   _diffrn_ambient_temperature ..... (K)        293 Check
PLAT794_ALERT_5_G Tentative Bond Valency for Fe        (IX)      .       8.10 Info
PLAT804_ALERT_5_G Number of ARU-Code Packing Problem(s) in PLATON           1 Info
PLAT910_ALERT_3_G Missing # of FCF Reflection(s) Below Theta(Min).          1 Note
PLAT912_ALERT_4_G Missing # of FCF Reflections Above STh/L=  0.600        177 Note
PLAT961_ALERT_5_G Dataset Contains no Negative Intensities .......     Please Check

   2 ALERT level A = Most likely a serious problem - resolve or explain
   2 ALERT level B = A potentially serious problem, consider carefully
   3 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   9 ALERT level G = General information/check it is not something unexpected

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


checkCIF publication errors

Alert level A
PUBL024_ALERT_1_A The number of authors is greater than 5.
              Please specify the role of each of the co-authors
              for your paper.

   1 ALERT level A = Data missing that is essential or data in wrong format
   0 ALERT level G = General alerts. Data that may be required is missing

---

Computing details

Data collection: CrysAlis PRO (Rigaku OD, 2018); cell refinement: CrysAlis PRO (Rigaku OD, 2018); data reduction: CrysAlis PRO (Rigaku OD, 2018); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

Iron tetranitride

Crystal data

FeN4	Z = 1
Mr = 111.89	F(000) = 54
Triclinic, P1	Dx = 6.953 Mg m^−3
a = 2.4473 (10) Å	Synchrotron radiation, λ = 0.30996 Å
b = 3.4688 (14) Å	Cell parameters from 68 reflections
c = 3.5144 (13) Å	θ = 2.8–16.1°
α = 105.22 (4)°	µ = 1.33 mm^−1
β = 110.60 (4)°	T = 293 K
γ = 91.39 (3)°	Irregular, black
V = 26.72 (2) Å^3	0.001 × 0.001 × 0.001 mm

Data collection

ID11 @ ESRF diffractometer	71 independent reflections
Radiation source: synchrotron	70 reflections with I > 2σ(I)
Synchrotron monochromator	Rint = 0.020
ω scans	θmax = 16.2°, θmin = 2.8°
Absorption correction: multi-scan (ABSPACK; Oxford Diffraction, 2005)	h = −3→3
Tmin = 0.967, Tmax = 1.000	k = −5→4
117 measured reflections	l = −6→5

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	Primary atom site location: dual
R[F^2 > 2σ(F^2)] = 0.040	w = 1/[σ^2(Fo^2) + (0.0282P)^2 + 0.3122P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.082	(Δ/σ)max < 0.001
S = 1.18	Δρmax = 0.76 e Å^−3
71 reflections	Δρmin = −0.56 e Å^−3
10 parameters

Special details

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.

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

	x	y	z	Uiso*/Ueq
Fe	0.5000	0.0000	0.0000	0.0072 (4)*
N1	0.163 (4)	−0.346 (4)	−0.485 (2)	0.0066 (10)*
N2	0.065 (3)	−0.309 (4)	−0.861 (2)	0.0068 (10)*

Geometric parameters (Å, º)

Fe—Fe^i	2.4473 (10)	Fe—N2^vii	1.763 (6)
Fe—Fe^ii	2.4473 (10)	N1—N1^viii	1.277 (14)
Fe—N1	1.707 (10)	N1—N2	1.298 (8)
Fe—N1^iii	1.707 (10)	N2—Fe^ix	1.763 (6)
Fe—N2^iv	1.783 (14)	N2—Fe^x	1.783 (14)
Fe—N2^v	1.783 (14)	N2—N2^xi	1.37 (3)
Fe—N2^vi	1.763 (6)
Fe^i—Fe—Fe^ii	180.0	N2^vii—Fe—Fe^ii	46.7 (5)
N1—Fe—Fe^i	96.6 (4)	N2^iv—Fe—Fe^ii	133.98 (18)
N1^iii—Fe—Fe^ii	96.6 (4)	N2^iv—Fe—Fe^i	46.02 (18)
N1—Fe—Fe^ii	83.4 (4)	N2^vii—Fe—N2^v	92.7 (5)
N1^iii—Fe—Fe^i	83.4 (4)	N2^vi—Fe—N2^v	87.3 (5)
N1^iii—Fe—N1	180.0	N2^v—Fe—N2^iv	180.0 (7)
N1—Fe—N2^vii	81.3 (4)	N2^vii—Fe—N2^iv	87.3 (5)
N1^iii—Fe—N2^vii	98.7 (4)	N2^vi—Fe—N2^iv	92.7 (5)
N1^iii—Fe—N2^vi	81.3 (4)	N2^vi—Fe—N2^vii	180.0
N1—Fe—N2^vi	98.7 (4)	N1^viii—N1—Fe	118.9 (9)
N1—Fe—N2^iv	90.5 (5)	N1^viii—N1—N2	109.6 (9)
N1—Fe—N2^v	89.5 (5)	N2—N1—Fe	129.4 (9)
N1^iii—Fe—N2^v	90.5 (5)	Fe^ix—N2—Fe^x	87.3 (5)
N1^iii—Fe—N2^iv	89.5 (5)	N1—N2—Fe^x	110.9 (12)
N2^vi—Fe—Fe^i	46.7 (5)	N1—N2—Fe^ix	126.9 (5)
N2^vi—Fe—Fe^ii	133.3 (5)	N1—N2—N2^xi	107.6 (12)
N2^vii—Fe—Fe^i	133.3 (5)	N2^xi—N2—Fe^x	113.1 (6)
N2^v—Fe—Fe^ii	46.02 (18)	N2^xi—N2—Fe^ix	109.9 (9)
N2^v—Fe—Fe^i	133.98 (18)

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