Chemistry Reference
In-Depth Information
0.1
0.08
0.06
0.04
0.02
0
-0.02
-1.5
-1
-0.5
0
0.5
1
1.5
Fig. 8 Bis(pentacarbonylmanganese) Mn
2
(CO)
10
.
Top
: Source function percentage contributions
to the M-Mn (
left
), Mn-C
eq
(
middle
), and (C-O)
eq
(
right
) bcp densities.
Bottom
: Source function
profiles (
left
) along the Mn-Mn internuclear axis for Mn
2
(CO)
10
(
blue lines
) and the model system
composed by two noninteracting Mn(CO)
5
fragments (
red lines
); delocalization indices (
right
).
In part and adapted from Figs. 4 and 5, with permission from [
14
],
http://pubs.rsc.org/en/Content/
ArticleLanding/2007/FD/b605404h
Copyright 2007, The Royal Society of Chemistry (RSC)
H-bond always suffice to ensure a positive contribution to the HB bcp density, it is
the sum of contributions from all atoms other than the bonded ones that ensures the
necessary positive density at the Mn-Mn bcp in Mn
2
(CO)
10
. This result neatly
complies with the dominant role the ligands have in causing the two metal atoms to
be bonded to one another and characterizes the M-M interaction as a multicenter
one or, perhaps more correctly, as a one
determined
by a multicenter synergic
cooperation.
Interaction with the carbonyl ligands polarizes the metal atomic Laplacian
distribution in such a way that the metal determines a subtraction rather than a
positive contribution to the density at the Mn-Mn bcp. Inspection of the profiles of
the SF (Fig.
8
, bottom left) and of the LS (Fig.
9
) along the Mn-Mn bond path
enables one to have a deeper understanding on how this negative density contribu-
tion at the Mn-Mn bcp from the Mn atoms originates.
In Fig.
8
(bottom left), profiles of the SF contributions from the metal atoms and
from the two axial and the eight equatorial carbonyl groups are compared for
Mn
2
(CO)
10
(blue curves) and a model system made by two noninteracting Mn
(CO)
5
fragments (red curves), placed in the same geometry as in Mn
2
(CO)
10
.
Noninteracting fragments mean that the electron density rearrangement due to the
Mn-Mn bond formation has been
switched off
, while each fragment retains its DFT
self-consistently determined electron distribution. The SF contribution from the
