Rep:Mod:TAw0133700117

BH₃

B3LYP/6-31G(d.p) level

         Item               Value     Threshold  Converged?
 Maximum Force            0.000006     0.000450     YES
 RMS     Force            0.000004     0.000300     YES
 Maximum Displacement     0.000023     0.001800     YES
 RMS     Displacement     0.000015     0.001200     YES

Frequency analysis log file bh3_frequency.log

 Low frequencies ---   -2.2126   -1.0751   -0.0054    2.2359   10.2633   10.3194
 Low frequencies --- 1162.9860 1213.1757 1213.1784

BH3

Vibrational spectrum for NH₃

wavenumber (cm-1	Intensity (arbitrary units)	symmetry	IR active?	type
1163	93	A"2	yes	out-of-plane bend
1213	14	E'	very slight	in-plane bend
1213	14	E'	very slight	in-plane bend
2582	0	A'1	no	symmetric stretch
2715	126	E'	yes	asymmetric stretch
2715	126	E'	yes	asymmetric stretch

In the spectrum there are less than 6 peaks. This is because there are two sets of vibrations with degenerate energies, these sets occur at frequencies 1213 and 2715. As a result, 4 vibrations are represented by two peaks. There is also a stretch at 2583, however since it is a symmetric stretch, it is not IR active and as a result does not appear on the spectrum. Therefore, only 3 peaks should be seen in the spectrum.

BH₃ Molecular Orbital Diagram

Need to ask demonstrators.

NH₃

B3LYP/6-31G(d.p) level

         Item               Value     Threshold  Converged?
 Maximum Force            0.000006     0.000450     YES
 RMS     Force            0.000004     0.000300     YES
 Maximum Displacement     0.000014     0.001800     YES
 RMS     Displacement     0.000009     0.001200     YES

Frequency analysis log file NH3_frequency.log

Low frequencies ---   -0.0128   -0.0018   -0.0014    7.1032    8.1046    8.1049
Low frequencies --- 1089.3834 1693.9368 1693.9368

NH3

NH₃BH₃

B3LYP/6-31G(d.p) level

         Item               Value     Threshold  Converged?
 Maximum Force            0.000122     0.000450     YES
 RMS     Force            0.000058     0.000300     YES
 Maximum Displacement     0.000582     0.001800     YES
 RMS     Displacement     0.000320     0.001200     YES

Frequency analysis log file NH3BH3_frequency.log

Low frequencies ---   -0.0014    0.0010    0.0011   16.8481   17.4133   37.2932
Low frequencies ---  265.8219  632.2116  639.3277

NH3BH3

Energy of N-B Bond

E(NH₃) = -56.55776873 a.u.

E(BH₃) = -26.61532364 a.u.

E(NH₃BH₃) = -83.22468893 a.u.

Association energy = E(NH₃BH₃) - [E(NH₃)+E(BH₃)] = -83.22468893 - (-26.61532364 + -56.5577687) = -0.05159659 a.u. = -135.466847 kJ/mol

need to make comments about bond strength, ask demonstrator for comparison to literature value,