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Dear Partha, are you familiar with the IUPAC definition of a hydrogen bond?
E.g. here: http://publications.iupac.org/pac/pdf/2011/pdf/8308x1637.pdf">http://publications.iupac.org/pac/pdf/2011/pdf/8308x1637.pdf Based on that, it’s clear that there is indeed a
POSSIBILITY of a H-bond, as you have a potential H-bond donor (N-H) and two
possible acceptors (the N atoms, and the pi-electron system). However, it also
seems likely that the interaction will
be quite weak, to the point of the existence of a H-bond being a borderline
case, likely depending on the conditions (see the footnotes in the linked
pdf). Some quick-and-dirty calculations on my laptop (using Spartan
’20, wB97xD and a 6-31+G(d) basis set set - and yes I know there are
better basis sets available but this should be
good enough for the present
purpose) confirm this: for the H-bond to the N atom, the distance is
pretty large (H…N is almost 2.4 Å), the NHN angle is far from linear
(about 129 degrees), the N-H bond length
increase and vibrational redshift (compared to isolated methyl amine) are on
the order of 0.002 Å and a few wavenumbers,
respectively, and interaction energy is only about 20 kJ/mol (of which a
lot, possibly even
most, is probably just basis set superposition error due to my small
basis set). For the H-bond to the pi-system, the distance (to the center of
the ring) is even longer (almost 2.6 Å), the interaction energy is even
lower (about 10 kJ/mol), the N-H bond length is identical
(to 0.001 Å) to isolated methyl amine, and the
frequencies are actually blueshifted by a few cm-1
(the latter may just be an artefact though). So this is likely
not a H-bond at all, as per the IUPAC definition Whether or not you want to call the first interaction (from the
methyl amine NH to the pyrazine N) a H-bond really really depends on what you
want to do with this information. Best regards, Theo Kurtén (University of Helsinki, Finland) From:
owner-chemistry+theo.kurten==helsinki.fi/a\ccl.net
<owner-chemistry+theo.kurten==helsinki.fi/a\ccl.net> on behalf of Partha
Sengupta anapspsmo=gmail.com <owner-chemistry/a\ccl.net> I am not interested in
ChatGpt. I ask the question to be answered from a chemical point of view. I
repeat the question again" Is there any possibility between the hydrogen
bond formation between pyrazine and
methyl amine". If there is any chance please give me the
references. Partha --
Dr. Partha
Sarathi Sengupta |