Inelastic Neutron Scattering Spectroscopy of Diazenides: Detection of the NN Stretch

Abstract

Birds in a cage: The highly absorbent nitrogen‐rich compounds SrN and SrN2 hide their secrets from Raman scattering experiments, but when observed using inelastic neutron scattering, the dinitrogen can be shown to lie trapped within a cage of strontium atoms. Such a structure is shown in the graphic for SrN2, in which the dumbbell‐shaped dinitrogen can be clearly identified.

High Pressure Synthesis of Marcasite-Type Rhodium Pernitride

“…Furthermore, the strong Raman peak (∼800 cm –1 ) for PtN 2 is well consistent with that of single-bonded polymeric nitrogen. ,, These findings strongly suggested that dinitrogen (N–N) in PtN 2 exhibits a single-bond nature. In the case of rhodium pernitride, the Raman peak frequency (∼1100 cm –1 ) characterized as dinitrogen is higher than that of PtN 2 , and single-bonded polymeric nitrogen (∼800 cm –1 ), while it is lower than the frequency of 1300–1550 cm –1 , which corresponds to double-bonded nitrogen deduced from N 2 H 2 and alkaline earth diazenides. ,, This observation indicates that the bond length of dinitrogen in marcasite-type RhN 2 is intermediate between single- and double-bonded dinitrogen. Further detailed discussion with respect to the Raman scattering measurements are described in Figures S4 and S5 of the Supporting Information.…”

“…The group theory analysis gives six active Raman modes (Γ = 2A g + 2B 1g + B 2g + B 3g ) for marcasite-type TX 2 ,and the Raman frequency modes are assigned with respect to the dumbbell-like X–X units . The vibron frequency of dinitrogen in pernitrides or molecules strongly depends on the bonding character, such as N–N (∼1.4 Å, ∼800 cm –1 ), NN (1.2–1.3 Å, 1300–1550 cm –1 ), − and NN (∼1.1 Å, ∼2400 cm –1 ). , Spectroscopic approaches combined with theoretical calculations have also been applied to platinum group metal nitrides. ,, Recent theoretical calculation studies reported that Pt 4+ and N 2 4– are the correct electronic valence states for PtN 2 . The anion N 2 4– is isoelectronic with that of the fluorine molecule, and the N–N bond length is well consistent with the F–F bond length (1.42 Å) .…”

High Pressure Synthesis of Marcasite-Type Rhodium Pernitride

“…Furthermore, the strong Raman peak (∼800 cm –1 ) for PtN 2 is well consistent with that of single-bonded polymeric nitrogen. ,, These findings strongly suggested that dinitrogen (N–N) in PtN 2 exhibits a single-bond nature. In the case of rhodium pernitride, the Raman peak frequency (∼1100 cm –1 ) characterized as dinitrogen is higher than that of PtN 2 , and single-bonded polymeric nitrogen (∼800 cm –1 ), while it is lower than the frequency of 1300–1550 cm –1 , which corresponds to double-bonded nitrogen deduced from N 2 H 2 and alkaline earth diazenides. ,, This observation indicates that the bond length of dinitrogen in marcasite-type RhN 2 is intermediate between single- and double-bonded dinitrogen. Further detailed discussion with respect to the Raman scattering measurements are described in Figures S4 and S5 of the Supporting Information.…”

“…The group theory analysis gives six active Raman modes (Γ = 2A g + 2B 1g + B 2g + B 3g ) for marcasite-type TX 2 ,and the Raman frequency modes are assigned with respect to the dumbbell-like X–X units . The vibron frequency of dinitrogen in pernitrides or molecules strongly depends on the bonding character, such as N–N (∼1.4 Å, ∼800 cm –1 ), NN (1.2–1.3 Å, 1300–1550 cm –1 ), − and NN (∼1.1 Å, ∼2400 cm –1 ). , Spectroscopic approaches combined with theoretical calculations have also been applied to platinum group metal nitrides. ,, Recent theoretical calculation studies reported that Pt 4+ and N 2 4– are the correct electronic valence states for PtN 2 . The anion N 2 4– is isoelectronic with that of the fluorine molecule, and the N–N bond length is well consistent with the F–F bond length (1.42 Å) .…”

Thermochemistry of a New Class of Materials Containing Dinitrogen Pairs in an Oxide Matrix

“…The experimental setup was described earlier 2 and Raman spectroscopy confirms the previous XPS results: a single peak close to 2328 cm -1 reveals that the retained nitrogen exists as N 2 entities within a symmetric environment. The Raman peak position compares to that of 2330 cm -1 in N 2 gas, 1380 cm -1 in SrN, and 1307 cm -1 in SrN 2 ((N 2 ) 2- pairs) …”

Synthesis of Alkaline Earth Diazenides MAEN2(MAE= Ca, Sr, Ba) by Controlled Thermal Decomposition of Azides under High Pressure

“…For SrN 2 and SrN (=(Sr 2+ ) 4 (N 3− ) 2 ([N 2 ] 2− ), a nitride-diazenide) inelastic neutron scattering (INS) spectroscopy already revealed that an observed feature at 1380 cm −1 (SrN) and 1307 cm −1 (SrN 2 ) can be assigned to the N−N stretching vibration of the diazenide ion. 46 Remaining features at considerably lower wavenumbers (<350 cm −1 ) were assigned to acoustic, optic translational and librational modes of the [N 2 ] 2− ion.…”

High Pressure Synthesis of Marcasite-Type Rhodium Pernitride

“…Furthermore, the strong Raman peak (∼800 cm –1 ) for PtN 2 is well consistent with that of single-bonded polymeric nitrogen. ,, These findings strongly suggested that dinitrogen (N–N) in PtN 2 exhibits a single-bond nature. In the case of rhodium pernitride, the Raman peak frequency (∼1100 cm –1 ) characterized as dinitrogen is higher than that of PtN 2 , and single-bonded polymeric nitrogen (∼800 cm –1 ), while it is lower than the frequency of 1300–1550 cm –1 , which corresponds to double-bonded nitrogen deduced from N 2 H 2 and alkaline earth diazenides. ,, This observation indicates that the bond length of dinitrogen in marcasite-type RhN 2 is intermediate between single- and double-bonded dinitrogen. Further detailed discussion with respect to the Raman scattering measurements are described in Figures S4 and S5 of the Supporting Information.…”

“…The group theory analysis gives six active Raman modes (Γ = 2A g + 2B 1g + B 2g + B 3g ) for marcasite-type TX 2 ,and the Raman frequency modes are assigned with respect to the dumbbell-like X–X units . The vibron frequency of dinitrogen in pernitrides or molecules strongly depends on the bonding character, such as N–N (∼1.4 Å, ∼800 cm –1 ), NN (1.2–1.3 Å, 1300–1550 cm –1 ), − and NN (∼1.1 Å, ∼2400 cm –1 ). , Spectroscopic approaches combined with theoretical calculations have also been applied to platinum group metal nitrides. ,, Recent theoretical calculation studies reported that Pt 4+ and N 2 4– are the correct electronic valence states for PtN 2 . The anion N 2 4– is isoelectronic with that of the fluorine molecule, and the N–N bond length is well consistent with the F–F bond length (1.42 Å) .…”

Thermochemistry of a New Class of Materials Containing Dinitrogen Pairs in an Oxide Matrix

“…The experimental setup was described earlier 2 and Raman spectroscopy confirms the previous XPS results: a single peak close to 2328 cm -1 reveals that the retained nitrogen exists as N 2 entities within a symmetric environment. The Raman peak position compares to that of 2330 cm -1 in N 2 gas, 1380 cm -1 in SrN, and 1307 cm -1 in SrN 2 ((N 2 ) 2- pairs) …”

Synthesis of Alkaline Earth Diazenides MAEN2(MAE= Ca, Sr, Ba) by Controlled Thermal Decomposition of Azides under High Pressure

“…For SrN 2 and SrN (=(Sr 2+ ) 4 (N 3− ) 2 ([N 2 ] 2− ), a nitride-diazenide) inelastic neutron scattering (INS) spectroscopy already revealed that an observed feature at 1380 cm −1 (SrN) and 1307 cm −1 (SrN 2 ) can be assigned to the N−N stretching vibration of the diazenide ion. 46 Remaining features at considerably lower wavenumbers (<350 cm −1 ) were assigned to acoustic, optic translational and librational modes of the [N 2 ] 2− ion.…”

High Pressure Synthesis of Marcasite-Type Rhodium Pernitride

“…Furthermore, the strong Raman peak (∼800 cm –1 ) for PtN 2 is well consistent with that of single-bonded polymeric nitrogen. ,, These findings strongly suggested that dinitrogen (N–N) in PtN 2 exhibits a single-bond nature. In the case of rhodium pernitride, the Raman peak frequency (∼1100 cm –1 ) characterized as dinitrogen is higher than that of PtN 2 , and single-bonded polymeric nitrogen (∼800 cm –1 ), while it is lower than the frequency of 1300–1550 cm –1 , which corresponds to double-bonded nitrogen deduced from N 2 H 2 and alkaline earth diazenides. ,, This observation indicates that the bond length of dinitrogen in marcasite-type RhN 2 is intermediate between single- and double-bonded dinitrogen. Further detailed discussion with respect to the Raman scattering measurements are described in Figures S4 and S5 of the Supporting Information.…”

“…The group theory analysis gives six active Raman modes (Γ = 2A g + 2B 1g + B 2g + B 3g ) for marcasite-type TX 2 ,and the Raman frequency modes are assigned with respect to the dumbbell-like X–X units . The vibron frequency of dinitrogen in pernitrides or molecules strongly depends on the bonding character, such as N–N (∼1.4 Å, ∼800 cm –1 ), NN (1.2–1.3 Å, 1300–1550 cm –1 ), − and NN (∼1.1 Å, ∼2400 cm –1 ). , Spectroscopic approaches combined with theoretical calculations have also been applied to platinum group metal nitrides. ,, Recent theoretical calculation studies reported that Pt 4+ and N 2 4– are the correct electronic valence states for PtN 2 . The anion N 2 4– is isoelectronic with that of the fluorine molecule, and the N–N bond length is well consistent with the F–F bond length (1.42 Å) .…”

Thermochemistry of a New Class of Materials Containing Dinitrogen Pairs in an Oxide Matrix

“…The experimental setup was described earlier 2 and Raman spectroscopy confirms the previous XPS results: a single peak close to 2328 cm -1 reveals that the retained nitrogen exists as N 2 entities within a symmetric environment. The Raman peak position compares to that of 2330 cm -1 in N 2 gas, 1380 cm -1 in SrN, and 1307 cm -1 in SrN 2 ((N 2 ) 2- pairs) …”

Synthesis of Alkaline Earth Diazenides MAEN2(MAE= Ca, Sr, Ba) by Controlled Thermal Decomposition of Azides under High Pressure

“…For SrN 2 and SrN (=(Sr 2+ ) 4 (N 3− ) 2 ([N 2 ] 2− ), a nitride-diazenide) inelastic neutron scattering (INS) spectroscopy already revealed that an observed feature at 1380 cm −1 (SrN) and 1307 cm −1 (SrN 2 ) can be assigned to the N−N stretching vibration of the diazenide ion. 46 Remaining features at considerably lower wavenumbers (<350 cm −1 ) were assigned to acoustic, optic translational and librational modes of the [N 2 ] 2− ion.…”