File:Asp216 borazine aromatic.png

2018-05-18T14:06:32Z

Asp216:

Rep:Mod:asp216 Y2

2018-05-18T14:06:17Z

Asp216: /* MOs */

==EX3 section==

===BH3===

<jmol><jmolApplet>
<title>Optimised borane molecule</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>ASP216_BH3_FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

'''RB3LYP/6-31G(d,p) level'''

[[File:Asp216_bh3_summary.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000190 0.000450 YES
RMS Force 0.000095 0.000300 YES
Maximum Displacement 0.000747 0.001800 YES
RMS Displacement 0.000374 0.001200 YES
</pre>

[[Media:ASP216_BH3_FREQ.LOG| Download optimised .log file here]]

'''Frequencies'''

<pre>
Low frequencies --- -0.2260 -0.1036 -0.0055 48.0278 49.0875 49.0880
Low frequencies --- 1163.7224 1213.6715 1213.6741
</pre>

{| class="wikitable" border=1
!wavenumber (cm-1) !! Intensity (arbitrary units) !! symmetry !! IR active? !! type
|-
| 1164 || 92 || A2" || Yes || Bend (out of plane)
|-
| 1214 || 14 || E' || slightly || Bend
|-
| 1214 || 14 || E' || slightly || Bend
|-
| 2580 || 0 || A1' || No || Symmetric Stretch
|-
| 2713 || 126 || E' || Yes || Asymmetric Stretch
|-
| 2713 || 126 || E' || Yes || Asymmetric Stretch
|}

[[File:Asp216_bh3_ir_spectrum.png]]

For borane, there are 6 vibrational modes but only 3 peaks are visible in the IR spectrum. The symmetric stretch (ν = 2580 cm-1) is not IR active as the stretch has no change in dipole moment. The two asymmetrics stretches are degenerate (have the same energy) as they vibrate at the same frequency and therefore the peaks overlap to form one. This is also true for the 2 bends (ν = 1214 cm-1).

'''MOs'''

There is little difference between the LCAO and calulated MOs. However, the calculated MOs better show the distribution of electron density across the molecule. It can also be seen that the unoccupied real MOs are more diffuse the occupied MOs, which cannot be realised from the LCAO MOs. This suggests that qualitative MO theory (LCAOs) is useful and reliable for occupied MOs, but less accurate for predicting unoccupied MOs.

For the antibonding MOs it can be seen how electron density is directed away from the B–H bond.

[[File:Asp216_bh3_mo.png|thumb|centre|MO diagram of BH3 showing LCAO MOs and calculated MOs]]

===NH3===

<jmol><jmolApplet>
<title>Optimised ammonia molecule</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>ASP216_NH3_FREQ_631G_DP.LOG</uploadedFileContents>
</jmolApplet></jmol>

'''RB3LYP/6-31G(d,p) level'''

[[File:Asp216_nh3_summary.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000086 0.000450 YES
RMS Force 0.000034 0.000300 YES
Maximum Displacement 0.000315 0.001800 YES
RMS Displacement 0.000106 0.001200 YES
</pre>

[[Media:ASP216_NH3_FREQ_631G_DP.LOG| Download optimised .log file here]]

'''Frequencies'''

<pre>
Low frequencies --- -30.2921 -30.2783 -0.0039 0.0080 0.0336 3.6335
Low frequencies --- 1088.7748 1694.0376 1694.0379
</pre>

{| class="wikitable" border=1
!wavenumber (cm-1) !! Intensity (arbitrary units) !! symmetry !! IR active? !! type
|-
| 1089 || 146 || A1 || Yes || Bend (out of plane)
|-
| 1694 || 14 || E || slightly || Bend
|-
| 1694 || 14 || E || slightly || Bend
|-
| 3462 || 1 || A1 || No || Symmetric stretch
|-
| 3591 || 0 || E || No || Asymmetric stretch
|-
| 3591 || 0 || E || No || Asymmetric stretch
|}

[[File:Asp216_nh3_ir_spectrum.png]]

===NH3BH3===

<jmol><jmolApplet>
<title>Optimised ammonia borane molecule</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>ASP216_NH3BH3_FREQ_631G_DP.LOG</uploadedFileContents>
</jmolApplet></jmol>

'''RB3LYP/6-31G(d,p) level'''

[[File:Asp216_nh3bh3_summary.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000237 0.000450 YES
RMS Force 0.000052 0.000300 YES
Maximum Displacement 0.001353 0.001800 YES
RMS Displacement 0.000365 0.001200 YES
</pre>

[[Media:ASP216_NH3BH3_FREQ_631G_DP.LOG| Download optimised .log file here]]

'''Frequencies'''

<pre>
Low frequencies --- -0.1948 -0.0607 -0.0067 10.8243 16.5775 16.5866
Low frequencies --- 263.0568 631.4015 638.8808
</pre>

====Energy Calculation====

E(NH3)= -56.55776861 a.u.

E(BH3)= -26.61532342 a.u.

E(NH3BH3)= -83.22469012 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]

ΔE= -83.22469012 - (-56.55776861 + -26.61532342)

ΔE= -0.05159809 a.u. = -135 kJmol-1

The dative bond between B and N in ammonia borane is relatively weak (dissociation energy = 135 kJmol-1), as it is less than that of a covalent C–C bond (350 kJmol-1) in isoelectronic ethane. <ref name="Organic" />

===BBr3===

<jmol><jmolApplet>
<title>Optimised borone tribromide molecule</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>ASP216_BBR3_FREQ_GEN2.log</uploadedFileContents>
</jmolApplet></jmol>

'''B3LYP/6-31G(d,p)LANL2DZ level'''

[[File:Asp216_bbr3_summary2.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000019 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000090 0.001800 YES
RMS Displacement 0.000045 0.001200 YES
</pre>

[[Media:ASP216_BBR3_FREQ_GEN2.log| Download optimised .log file here]]

{{DOI|10042/202414}}

<pre>
Low frequencies --- -0.0126 -0.0064 -0.0046 2.6412 2.6412 4.9503
Low frequencies --- 155.9599 155.9619 267.6868
</pre>

==Project Section==

===Benzene===

<jmol><jmolApplet>
<title>Optimised benzene molecule</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>ASP216_BENZENE_FREQ2_631G_DP.LOG</uploadedFileContents>
</jmolApplet></jmol>

'''RB3LYP/6-31G(d,p) level'''

[[File:Asp216_benzene_summary.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000198 0.000450 YES
RMS Force 0.000087 0.000300 YES
Maximum Displacement 0.000757 0.001800 YES
RMS Displacement 0.000321 0.001200 YES
</pre>

[[Media:ASP216_BENZENE_FREQ2_631G_DP.LOG| Download optimised .log file here]]

'''Frequencies'''

<pre>
Low frequencies --- -2.1456 -2.1456 -0.0088 -0.0042 -0.0041 10.4835
Low frequencies --- 413.9768 413.9768 621.1390
</pre>

===Borazine===

<jmol><jmolApplet>
<title>Optimised borazine molecule</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>ASP216_BORAZINE_FREQ2_631G_DP.LOG</uploadedFileContents>
</jmolApplet></jmol>

'''RB3LYP/6-31G(d,p) level'''

[[File:Asp216_borazine_summary.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000016 0.000450 YES
RMS Force 0.000005 0.000300 YES
Maximum Displacement 0.000025 0.001800 YES
RMS Displacement 0.000008 0.001200 YES
</pre>

[[Media:ASP216_BORAZINE_FREQ2_631G_DP.LOG | Download optimised .log file here]]

'''Frequencies'''

<pre>
Low frequencies --- -13.6679 -13.4715 -10.3782 -0.0099 0.0321 0.0716
Low frequencies --- 289.1330 289.1422 404.0164
</pre>

===Charge Distribution===

{| class="wikitable" border=1
! !! Benzene !! Borazine
|-
| || [[File:Asp216_benzene_charge.png|thumb|upright=1.5]] ||
[[File:Asp216_borazine_charge.png|thumb|upright=1.5]]
|-
| '''Charges on atom /e''' || C: -0.239, H: 0.239 || N: -1.102, B: 0.747, H(–N): 0.432, H(–B): -0.077
|}
The above colour scheme ranges from red at a charge of -1.102 and green at 1.102.

The distribution of charge in each molecule reflects that molecule's symmetry. In benzene, the D6h symmetry shows all carbon atoms have the same charge. This indicates the covalent nature of the C–C bonds in the ring, as the electron density is evenly spread across the C atoms with no polarised C–C bonds. Conversely, in borazine the nitrogen and boron ring atoms differ in their charge due to the fact that nitrogen is electronegative and boron is electropositive. The B–N bond is polarised and therefore has some ionic character.

There are different degrees of polarisation between the B–H and N–H bonds, with the N–H bond being more polarised. The greater ionic character shortens (1.097 Å) and strengthens the N–H bond more than the B–H bond (1.195 Å).

Both molecules have not overall charge, as the sum of charges of each atom are zero.

* quote eneg values and scale used to measure values

===MOs===

{| class="wikitable" border=1
! Benzene !! Borazine !! Comment
|-
|[[File:Asp216_benzene_mo22.png|thumb]] || [[File:Asp216_borazine_mo22.png|thumb]] || MO22 is one of the degenerate LUMO orbitals. This orbital shows some bonding character across two of the C–C/N–B bonds, but is ultimately destabilised by nodes across four of the C–C/N–B bonds leading to overall antibonding character. The benzene MO has e2u symmetry and the borazine MO has e" symmetry.
|-
|[[File:Asp216_benzene_mo21.png|thumb]] || [[File:Asp216_borazine_mo21.png|thumb]] || MO21 is one of the degenerate HOMO orbital. This is overall bonding with the lobes spread over ring atoms, but a few nodes along C–C/N–B bonds indicating antibonding character which destabilise the bonding character. In benzene it has e1g symmetry and for borazine it has e" symmetry. In borazine there is a larger contribution to the MO from the nitrogen atoms, evidenced by larger lobes over these atoms. N atoms are more electronegative than B and so its p orbitals are lower in energy, and are therefore closer in energy to the bonding MOs, giving them a larger contribution.
|-
|[[File:Asp216_benzene_mo13.png|thumb]] || [[File:Asp216_borazine_mo16.png|thumb]] || The MO13 of benzene has b1u symmetry and the MO16 of borazine e1' symmetry. These orbitals show only contribution from the sigma fragment orbitals of the H atoms, and are overall non-bonding. There is an equal contribution from each H atom in benzene but, the contributions are larger for H bonded to N and smaller for H bonded to B in borazine.
|}

'''Aromaticity'''

[[File:Asp216_benzene_aromatic.png|thumb]][[File:Asp216_borazine_aromatic.png|thumb]]

*discuss in your wiki (2-3 paragraphs) the concept of aromaticity, the simple ideas and also the more complex descriptions.
*how do the real MOs relate to the common (very basic) conceptions of aromaticity? you are expected to explain why the concept of overlapping pz AOs is NOT a good description for aromaticity.

extra interesting: core orbitals of borazine for boron and nitrogen atoms show the same symmetry as BH3.

==References==

<references>
<ref name="Organic">Clayden, J.; Greeves, N.; Warren, S. G. Organic chemistry; Oxford University Press: Oxford, 2012.</ref>
</references>

File:Asp216 borazine mo17.png

2018-05-18T14:03:07Z

Asp216: Asp216 uploaded a new version of File:Asp216 borazine mo17.png

File:Asp216 borazine mo17.png

2018-05-18T14:02:47Z

Asp216: Asp216 uploaded a new version of File:Asp216 borazine mo17.png

File:Asp216 borazine mo17.png

2018-05-18T14:01:52Z

Asp216: Asp216 uploaded a new version of File:Asp216 borazine mo17.png

Rep:Mod:asp216 Y2

2018-05-18T14:00:13Z

Asp216: /* MOs */

==EX3 section==

===BH3===

<jmol><jmolApplet>
<title>Optimised borane molecule</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>ASP216_BH3_FREQ.LOG</uploadedFileContents>
</jmolApplet></jmol>

'''RB3LYP/6-31G(d,p) level'''

[[File:Asp216_bh3_summary.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000190 0.000450 YES
RMS Force 0.000095 0.000300 YES
Maximum Displacement 0.000747 0.001800 YES
RMS Displacement 0.000374 0.001200 YES
</pre>

[[Media:ASP216_BH3_FREQ.LOG| Download optimised .log file here]]

'''Frequencies'''

<pre>
Low frequencies --- -0.2260 -0.1036 -0.0055 48.0278 49.0875 49.0880
Low frequencies --- 1163.7224 1213.6715 1213.6741
</pre>

{| class="wikitable" border=1
!wavenumber (cm-1) !! Intensity (arbitrary units) !! symmetry !! IR active? !! type
|-
| 1164 || 92 || A2" || Yes || Bend (out of plane)
|-
| 1214 || 14 || E' || slightly || Bend
|-
| 1214 || 14 || E' || slightly || Bend
|-
| 2580 || 0 || A1' || No || Symmetric Stretch
|-
| 2713 || 126 || E' || Yes || Asymmetric Stretch
|-
| 2713 || 126 || E' || Yes || Asymmetric Stretch
|}

[[File:Asp216_bh3_ir_spectrum.png]]

For borane, there are 6 vibrational modes but only 3 peaks are visible in the IR spectrum. The symmetric stretch (ν = 2580 cm-1) is not IR active as the stretch has no change in dipole moment. The two asymmetrics stretches are degenerate (have the same energy) as they vibrate at the same frequency and therefore the peaks overlap to form one. This is also true for the 2 bends (ν = 1214 cm-1).

'''MOs'''

There is little difference between the LCAO and calulated MOs. However, the calculated MOs better show the distribution of electron density across the molecule. It can also be seen that the unoccupied real MOs are more diffuse the occupied MOs, which cannot be realised from the LCAO MOs. This suggests that qualitative MO theory (LCAOs) is useful and reliable for occupied MOs, but less accurate for predicting unoccupied MOs.

For the antibonding MOs it can be seen how electron density is directed away from the B–H bond.

[[File:Asp216_bh3_mo.png|thumb|centre|MO diagram of BH3 showing LCAO MOs and calculated MOs]]

===NH3===

<jmol><jmolApplet>
<title>Optimised ammonia molecule</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>ASP216_NH3_FREQ_631G_DP.LOG</uploadedFileContents>
</jmolApplet></jmol>

'''RB3LYP/6-31G(d,p) level'''

[[File:Asp216_nh3_summary.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000086 0.000450 YES
RMS Force 0.000034 0.000300 YES
Maximum Displacement 0.000315 0.001800 YES
RMS Displacement 0.000106 0.001200 YES
</pre>

[[Media:ASP216_NH3_FREQ_631G_DP.LOG| Download optimised .log file here]]

'''Frequencies'''

<pre>
Low frequencies --- -30.2921 -30.2783 -0.0039 0.0080 0.0336 3.6335
Low frequencies --- 1088.7748 1694.0376 1694.0379
</pre>

{| class="wikitable" border=1
!wavenumber (cm-1) !! Intensity (arbitrary units) !! symmetry !! IR active? !! type
|-
| 1089 || 146 || A1 || Yes || Bend (out of plane)
|-
| 1694 || 14 || E || slightly || Bend
|-
| 1694 || 14 || E || slightly || Bend
|-
| 3462 || 1 || A1 || No || Symmetric stretch
|-
| 3591 || 0 || E || No || Asymmetric stretch
|-
| 3591 || 0 || E || No || Asymmetric stretch
|}

[[File:Asp216_nh3_ir_spectrum.png]]

===NH3BH3===

<jmol><jmolApplet>
<title>Optimised ammonia borane molecule</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>ASP216_NH3BH3_FREQ_631G_DP.LOG</uploadedFileContents>
</jmolApplet></jmol>

'''RB3LYP/6-31G(d,p) level'''

[[File:Asp216_nh3bh3_summary.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000237 0.000450 YES
RMS Force 0.000052 0.000300 YES
Maximum Displacement 0.001353 0.001800 YES
RMS Displacement 0.000365 0.001200 YES
</pre>

[[Media:ASP216_NH3BH3_FREQ_631G_DP.LOG| Download optimised .log file here]]

'''Frequencies'''

<pre>
Low frequencies --- -0.1948 -0.0607 -0.0067 10.8243 16.5775 16.5866
Low frequencies --- 263.0568 631.4015 638.8808
</pre>

====Energy Calculation====

E(NH3)= -56.55776861 a.u.

E(BH3)= -26.61532342 a.u.

E(NH3BH3)= -83.22469012 a.u.

ΔE=E(NH3BH3)-[E(NH3)+E(BH3)]

ΔE= -83.22469012 - (-56.55776861 + -26.61532342)

ΔE= -0.05159809 a.u. = -135 kJmol-1

The dative bond between B and N in ammonia borane is relatively weak (dissociation energy = 135 kJmol-1), as it is less than that of a covalent C–C bond (350 kJmol-1) in isoelectronic ethane. <ref name="Organic" />

===BBr3===

<jmol><jmolApplet>
<title>Optimised borone tribromide molecule</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>ASP216_BBR3_FREQ_GEN2.log</uploadedFileContents>
</jmolApplet></jmol>

'''B3LYP/6-31G(d,p)LANL2DZ level'''

[[File:Asp216_bbr3_summary2.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000019 0.000450 YES
RMS Force 0.000010 0.000300 YES
Maximum Displacement 0.000090 0.001800 YES
RMS Displacement 0.000045 0.001200 YES
</pre>

[[Media:ASP216_BBR3_FREQ_GEN2.log| Download optimised .log file here]]

{{DOI|10042/202414}}

<pre>
Low frequencies --- -0.0126 -0.0064 -0.0046 2.6412 2.6412 4.9503
Low frequencies --- 155.9599 155.9619 267.6868
</pre>

==Project Section==

===Benzene===

<jmol><jmolApplet>
<title>Optimised benzene molecule</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>ASP216_BENZENE_FREQ2_631G_DP.LOG</uploadedFileContents>
</jmolApplet></jmol>

'''RB3LYP/6-31G(d,p) level'''

[[File:Asp216_benzene_summary.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000198 0.000450 YES
RMS Force 0.000087 0.000300 YES
Maximum Displacement 0.000757 0.001800 YES
RMS Displacement 0.000321 0.001200 YES
</pre>

[[Media:ASP216_BENZENE_FREQ2_631G_DP.LOG| Download optimised .log file here]]

'''Frequencies'''

<pre>
Low frequencies --- -2.1456 -2.1456 -0.0088 -0.0042 -0.0041 10.4835
Low frequencies --- 413.9768 413.9768 621.1390
</pre>

===Borazine===

<jmol><jmolApplet>
<title>Optimised borazine molecule</title>
<color>black</color>
<size>200</size>
<uploadedFileContents>ASP216_BORAZINE_FREQ2_631G_DP.LOG</uploadedFileContents>
</jmolApplet></jmol>

'''RB3LYP/6-31G(d,p) level'''

[[File:Asp216_borazine_summary.PNG]]

<pre>
Item Value Threshold Converged?
Maximum Force 0.000016 0.000450 YES
RMS Force 0.000005 0.000300 YES
Maximum Displacement 0.000025 0.001800 YES
RMS Displacement 0.000008 0.001200 YES
</pre>

[[Media:ASP216_BORAZINE_FREQ2_631G_DP.LOG | Download optimised .log file here]]

'''Frequencies'''

<pre>
Low frequencies --- -13.6679 -13.4715 -10.3782 -0.0099 0.0321 0.0716
Low frequencies --- 289.1330 289.1422 404.0164
</pre>

===Charge Distribution===

{| class="wikitable" border=1
! !! Benzene !! Borazine
|-
| || [[File:Asp216_benzene_charge.png|thumb|upright=1.5]] ||
[[File:Asp216_borazine_charge.png|thumb|upright=1.5]]
|-
| '''Charges on atom /e''' || C: -0.239, H: 0.239 || N: -1.102, B: 0.747, H(–N): 0.432, H(–B): -0.077
|}
The above colour scheme ranges from red at a charge of -1.102 and green at 1.102.

The distribution of charge in each molecule reflects that molecule's symmetry. In benzene, the D6h symmetry shows all carbon atoms have the same charge. This indicates the covalent nature of the C–C bonds in the ring, as the electron density is evenly spread across the C atoms with no polarised C–C bonds. Conversely, in borazine the nitrogen and boron ring atoms differ in their charge due to the fact that nitrogen is electronegative and boron is electropositive. The B–N bond is polarised and therefore has some ionic character.

There are different degrees of polarisation between the B–H and N–H bonds, with the N–H bond being more polarised. The greater ionic character shortens (1.097 Å) and strengthens the N–H bond more than the B–H bond (1.195 Å).

Both molecules have not overall charge, as the sum of charges of each atom are zero.

* quote eneg values and scale used to measure values

===MOs===

{| class="wikitable" border=1
! Benzene !! Borazine !! Comment
|-
|[[File:Asp216_benzene_mo22.png|thumb]] || [[File:Asp216_borazine_mo22.png|thumb]] || MO22 is one of the degenerate LUMO orbitals. This orbital shows some bonding character across two of the C–C/N–B bonds, but is ultimately destabilised by nodes across four of the C–C/N–B bonds leading to overall antibonding character. The benzene MO has e2u symmetry and the borazine MO has e" symmetry.
|-
|[[File:Asp216_benzene_mo21.png|thumb]] || [[File:Asp216_borazine_mo21.png|thumb]] || MO21 is one of the degenerate HOMO orbital. This is overall bonding with the lobes spread over ring atoms, but a few nodes along C–C/N–B bonds indicating antibonding character which destabilise the bonding character. In benzene it has e1g symmetry and for borazine it has e" symmetry. In borazine there is a larger contribution to the MO from the nitrogen atoms, evidenced by larger lobes over these atoms. N atoms are more electronegative than B and so its p orbitals are lower in energy, and are therefore closer in energy to the bonding MOs, giving them a larger contribution.
|-
|[[File:Asp216_benzene_mo13.png|thumb]] || [[File:Asp216_borazine_mo16.png|thumb]] || The MO13 of benzene has b1u symmetry and the MO16 of borazine e1' symmetry. These orbitals show only contribution from the sigma fragment orbitals of the H atoms, and are overall non-bonding. There is an equal contribution from each H atom in benzene but, the contributions are larger for H bonded to N and smaller for H bonded to B in borazine.
|}

'''Aromaticity'''

[[File:Asp216_benzene_mo17.png|thumb]][[File:Asp216_borazine_mo17.png|thumb]]

*discuss in your wiki (2-3 paragraphs) the concept of aromaticity, the simple ideas and also the more complex descriptions.
*how do the real MOs relate to the common (very basic) conceptions of aromaticity? you are expected to explain why the concept of overlapping pz AOs is NOT a good description for aromaticity.

extra interesting: core orbitals of borazine for boron and nitrogen atoms show the same symmetry as BH3.

==References==

<references>
<ref name="Organic">Clayden, J.; Greeves, N.; Warren, S. G. Organic chemistry; Oxford University Press: Oxford, 2012.</ref>
</references>

File:Asp216 borazine mo17.png

2018-05-18T13:58:49Z

Asp216: Asp216 uploaded a new version of File:Asp216 borazine mo17.png