A pseudo-cage complex of silver(I) with tripodal tetraamine having benzyl end groups, {tris[2-(benzylamino)-ethyl]amine-κ4N}silver(I) perchlorate

Article abstract of DOI:10.1107/S0108270102000665

The synthesis and crystal structure of {tris[2-(benzylamino)-ethyl]amine-κ⁴N}silver(I) perchlorate, [Ag(C₂₇H₃₆N₄)]ClO₄ or [Ag(bz₃tren)]ClO₄ {bz₃tren is tris[2-(benzylamino)ethyl]-amine or N,N′,N″-tribenzyltris(2-aminoethyl)amine} are reported. The Ag atom is coordinated to four N atoms of the tren unit and is located 0.604 (3) A out of the trigonal plane described by the three secondary amine N atoms, away from the bridgehead N atom. Edge-to-face π-π interactions between the aromatic end groups, and weak interactions between Ag and arene, allow the formation of a pseudo-cage complex.

Full text of DOI:10.1107/S0108270102000665

metal-organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
end groups have not yet been reported. As part of our
continuing studies (Lee et al., 1995; Chung et al., 1997) invol-
ving such multipodal ligands and their pseudo-cyclic
complexes, the present ligand was chosen with this aspect in
mind. We report herein our result in this area, with the crystal
structure of {tris[2-(benzylamino)ethyl]amine-ꢀ4N}silver(I)
perchlorate, [Ag(bz3tren)]ClO4, (I).
As shown in Fig. 1, the Ag atom in (I) is coordinated to the
bridgehead N atom (Nbr) and to three secondary amino N
atoms (N2, N3 and N4). Upon complexation, the tren unit
becomes quite rigid and maintains the endo conformation,
ISSN 0108-2701
A pseudo-cage complex of silver(I)
with tripodal tetraamine having benzyl
end groups, {tris[2-(benzylamino)-
ethyl]amine-j4N}silver(I) perchlorate
Ê
with the Nbr atom displaced by 0.387 (6) A towards the Ag
atom above the triangular plane through atoms C1, C10 and
C19. The N1ÐCÐCÐN torsion angles are in the range
61.1 (6)±62.5 (6)ꢀ, suggesting gauche conformations. The Ag
Il Yoon,a Yong Woon Shin,a Jineun Kim,a Ki-Min Park,a
Sung Bae Parkb and Shim Sung Leea*
Ê
atom is displaced by 0.604 (3) A out of the trigonal plane
described by the three secondary amines, away from the Nbr
aDepartment of Chemistry and Research Institute of Natural Sciences, Gyeongsang
National University, Chinju 660-701, South Korea, and bDepartment of Chemistry,
Inje University, Kimhae 621-749, South Korea
Ê
atom. The AgÐNbr bond [2.507 (5) A] is at the upper end of
Correspondence e-mail: sslee@nongae.gsnu.ac.kr
the range for AgÐNbr (Ferguson et al., 1989; Adam et al.,
1995), and is signi®cantly longer than the other AgÐN bonds
Ê
in (I) [2.350 (3)±2.362 (3) A]. Selected geometric parameters
and the hydrogen-bonding geometry are listed in Tables 1 and
2, respectively.
Received 16 November 2001
Accepted 11 January 2002
Online 20 February 2002
The potential threefold symmetry of the complex cation in
(I) is broken by the non-coordinating ClO4 ion and the three
less well aligned aromatic end groups. The three aromatic
rings are essentially planar and lie nearly perpendicular to
each other, displaying dihedral angles of 73.1 (2), 67.0 (2) and
65.7 (2)ꢀ. This permits weak edge-to-face ꢁ±ꢁ interactions
between the aromatic end groups, with a distance from atom
C9 to the centroid of the neighbouring C22±C27 ring of
The synthesis and crystal structure of {tris[2-(benzylamino)-
ethyl]amine-ꢀ4N}silver(I) perchlorate, [Ag(C27H36N4)]ClO4
or [Ag(bz3tren)]ClO4 {bz3tren is tris[2-(benzylamino)ethyl]-
amine or N,N0,N00-tribenzyltris(2-aminoethyl)amine} are
reported. The Ag atom is coordinated to four N atoms of
Ê
the tren unit and is located 0.604 (3) A out of the trigonal
plane described by the three secondary amine N atoms, away
from the bridgehead N atom. Edge-to-face ꢁ±ꢁ interactions
between the aromatic end groups, and weak interactions
between Ag and arene, allow the formation of a pseudo-cage
complex.
Ê
3.856 (8) A, from atom C14 to the centroid of the neigh-
Ê
bouring C4±C9 ring of 3.962 (8) A and from atom C23 to the
Ê
centroid of the neighbouring C13±C18 ring of 3.989 (8) A.
The principal distortion of the coordination sphere arises
from the shift of the Ag atom out of the trigonal plane. The
Comment
Tripodal complexes with transition metals have been widely
investigated. The ligands used most in this area have been
tren, the tripodal tetraamine N(CH2CH2NH2)3, and its deri-
vatives (Zipp et al., 1974). Many cage complexes, such as
bimetallic complexes with bis(tren) cryptands, have also been
reported (Amendola et al., 2001). Acyclic ionophores with
aromatic end groups, so-called podands, sometimes form
unusual pseudo-cyclic complexes with alkali or soft metal ions
via intramolecular ꢁ±ꢁ interactions between two aromatic end
groups (Weber & Saenger, 1979). However, tripodal pseudo-
cage complexes formed by ꢁ±ꢁ interactions between aromatic
Figure 1
A perspective view of compound (I) with the atom-numbering scheme.
Displacement ellipsoids are drawn at the 30% probability level and H
atoms have been omitted for clarity.
Acta Cryst. (2002). C58, m165±m166
DOI: 10.1107/S0108270102000665
# 2002 International Union of Crystallography m165

metal-organic compounds
Ê
Table 1
Selected geometric parameters (A, ).
shortest AgÁ Á ÁCarene distance is 3.383 (6) A, well outside the
ꢀ
Ê
Ê
normal AgÁ Á Áꢁ interaction range (2.47±2.76 A; Munakata et
al., 1998). The shift of the Ag atom towards the aromatic end
groups, and the elongation of the AgÐNbr bond, which is
AgÐN4
AgÐN2
2.353 (3)
2.350 (3)
AgÐN3
AgÐN1
2.362 (3)
2.507 (5)
Ê
about 0.15 A longer than the other AgÐN bonds, may re¯ect,
N4ÐAgÐN2
N4ÐAgÐN3
N2ÐAgÐN3
111.22 (13)
114.19 (13)
115.53 (13)
N4ÐAgÐN1
N2ÐAgÐN1
N3ÐAgÐN1
75.34 (14)
75.27 (14)
74.79 (13)
at least in part, the presence of an additional long-range
AgÁ Á Áarene interaction (Galka & Gade, 1999).
The ꢁ±ꢁ interactions between the benzyl end groups, and
the partial contribution of the weak AgÁ Á Áarene interactions,
allow little room for anion or solvent, which usually coordi-
nates to a metal centre to give the ®ve-coordinate geometry
normally observed in tripodal ligands of similar structures.
Table 2
Hydrogen-bonding geometry (A, ).
ꢀ
Ê
DÐHÁ Á ÁA
DÐH
HÁ Á ÁA
2.58
DÁ Á ÁA
DÐHÁ Á ÁA
N4ÐH4Á Á ÁO3
0.90
3.481 (8)
179
Experimental
The ligand was synthesized according to the procedure published by
Ibrahim et al. (2001), with slight modi®cations. To a solution
containing bz3tren in acetonitrile was added a solution of an equi-
molar amount of silver perchlorate dissolved in acetonitrile. Slow
evaporation of the resulting solution in the dark afforded colourless
crystals of (I) suitable for X-ray crystallographic analysis.
Data collection: SMART (Siemens, 1996); cell re®nement: SAINT
(Siemens, 1996); data reduction: SHELXTL (Siemens, 1996);
program(s) used to solve structure: SHELXTL; program(s) used to
re®ne structure: SHELXTL; molecular graphics: SHELXTL; soft-
ware used to prepare material for publication: SHELXTL.
Crystal data
This work was supported by Korean Research Foundation
grant No. KRF-2000-015-DP0218.
3
[Ag(C27H36N4)]ClO4
Mr = 623.92
Monoclinic, Cc
Dx = 1.420 Mg m
Mo Kꢃ radiation
Cell parameters from 9303
re¯ections
Ê
a = 16.0287 (11) A
Ê
b = 9.6132 (7) A
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: OB1051). Services for accessing these data are
described at the back of the journal.
ꢄ = 2.2±28.3ꢀ
ꢅ = 0.82 mm
T = 296 (2) K
1
Ê
c = 20.2697 (15) A
ꢂ = 110.906 (1)ꢀ
3
Ê
V = 2917.7 (4) A
Z = 4
Block, colourless
0.5 Â 0.4 Â 0.4 mm
References
Data collection
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Bashall, A., Powell, H. R. & Tasker, P. A. (1995). J. Chem. Soc. Dalton
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Siemens SMART CCD area-
detector diffractometer
' and ! scans
9303 measured re¯ections
3627 independent re¯ections (plus
1637 Friedel-related re¯ections)
4068 re¯ections with I > 2ꢆ(I)
Rint = 0.026
ꢄ
max = 28.3ꢀ
h = 15 ! 21
k = 12 ! 11
l = 26 ! 18
Re®nement
Re®nement on F2
R[F2 > 2ꢆ(F2)] = 0.033
wR(F2) = 0.090
S = 0.99
5264 re¯ections
w = 1/[ꢆ2(Fo2) + (0.0536P)2
+ 0.2006P]
where P = (Fo2 + 2Fc2)/3
(Á/ꢆ)max < 0.001
3
Ê
Áꢇmax = 0.32 e A
3
Ê
0.31 e A
334 parameters
H-atom parameters constrained
Áꢇmin
=
Absolute structure: Flack (1983)
Flack parameter = 0.02 (3)
Ê
H atoms were added at calculated positions, with CÐH = 0.96 A
Ê
and NÐH = 0.90 A, and re®ned using a riding model, with Uiso
1.2Ueq of the parent atom.
=
Weber, G. & Saenger, W. (1979). Acta Cryst. B35, 1346±1349.
Zipp, S. G., Zipp, A. P. & Madan, S. K. (1974). Coord. Chem. Rev. 14, 29±45.
ꢁ
m166 Il Yoon et al. [Ag(C27H36N4)]ClO4
Acta Cryst. (2002). C58, m165±m166