Solid state structure and solution behaviour of organoselenium(ii) compounds containing 2-{E(CH2CH2)2NCH 2}C6H4 groups (E = O, NMe)

Article abstract of DOI:10.1039/b702629c

Cleavage of the Se-Se bond in [2-{O(CH₂CH₂) ₂NCH₂}C₆H₄]₂Se ₂ (1) and [2-{MeN(CH₂CH₂)₂NCH ₂}C₆H₄]

Full text of DOI:10.1039/b702629c

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www.rsc.org/dalton | Dalton Transactions
Solid state structure and solution behaviour of organoselenium(II) compounds
containing 2-{E(CH2CH2)2NCH2}C6H4 groups (E = O, NMe)†
Monika Kulcsar,a Anca Beleaga,a Cristian Silvestru,a Alina Nicolescu,b Calin Deleanu,c Cristina Todascac and
Anca Silvestru*a
Received 20th February 2007, Accepted 2nd April 2007
First published as an Advance Article on the web 23rd April 2007
DOI: 10.1039/b702629c
Cleavage of the Se–Se bond in [2-{O(CH2CH2)2NCH2}C6H4]2Se2 (1) and [2-{MeN(CH2CH2)2NCH2}-
C6H4]2Se2 (2) by treatment with SO2Cl2, bromine or iodine (1 : 1 molar ratio) yielded [2-{O(CH2CH2)2-
NCH2}C6H4]SeX [X = Cl (3), Br (4), I (5)] and [2-{MeN(CH2CH2)2NCH2}C6H4]SeI (6). The
compounds were characterized in solution by NMR spectroscopy (1H, 13C, 15N, 77Se, 2D experiments).
The solid-state molecular structures of 1–3, 4·HBr, 5 and 6 were established by single crystal X-ray
diffraction. In all cases T-shaped coordination geometries, i.e. (C,N)SeSe (1, 2), (C,N)SeX (3, 5, 6;
X = halogen) or CSeBr2 (4·HBr), were found. Supramolecular associations in crystals based on
hydrogen contacts are discussed.
(2) were obtained using the ortho-lithiation route.8 The organo-
Introduction
lithium reagents [2-E(CH2CH2)2NCH2}C6H4]Li (E = O, NMe)
The chemistry of organoselenium(II) compounds containing an
were obtained as white solids by the direct metallation of 2-
intramolecular N → Se interaction has attracted considerable in-
terest in recent years,1–5 mainly due to their use in organic synthesis,
as enzyme mimics and chemotherapeutic agents or the potential
of 2-(N,N-dimethylaminomethyl)phenyl and related derivatives to
stabilize exotic species such as the covalent azide [2-(Me2NCH2)-
C6H4]SeN3,5 or the trihalide [2-(Me2NCH2)C6H4]SeCl3.6 Recently,
we have reported on the synthesis, solution behaviour and molecu-
lar structures of various hypervalent organoselenium compounds
containing the 2-(Me2NCH2)C6H4 group.6,7 As a development of
our previous studies on organoselenium compounds we decided
to use bulkier organic groups with potential for additional
coordination to the chalcogen centre through donor atoms.
We report here on the synthesis and characterization, both in
solution and solid state, of new hypervalent organoselenium com-
pounds containing 2-{E(CH2CH2)2NCH2}C6H4 moieties (E = O,
NMe).
{E(CH2CH2)2NCH2}C6H4Br with n-BuLi in anhydrous hexane–
diethyl ether. The treatment of a THF solution of RLi with finely
ground selenium powder, under argon, followed by air oxidation,
resulted in isolation of R–Se–Se–R derivatives (Scheme 1).
Scheme 1
The organoselenium(II) halides, [2-{O(CH2CH2)2NCH2}C6H4]-
SeX [X = Cl (3), Br (4), I (5)] and [2-{MeN(CH2CH2)2NCH2}-
C6H4]SeI (6), were prepared in good yield by cleavage of the
Se–Se bond with SO2Cl2, elemental Br2 or I2 (1 : 1 molar ratio),
respectively, at room temperature, in carbon tetrachloride or
chloroform (Scheme 1).
Results and discussion
Synthesis
The compounds were isolated as stable, yellow (1–4) or red (5,
6) crystalline solids from CH2Cl2–n-hexane mixtures. Elemental
analytical data, together with NMR data are consistent with the
anticipated formulas. Single crystals suitable for X-ray diffraction
studies were obtained from a CH2Cl2–n-hexane mixture for all
compounds.
The new diorganodichalcogen(I) derivatives [2-{O(CH2CH2)2-
NCH2}C6H4]2Se2 (1) and [2-{MeN(CH2CH2)2NCH2}C6H4]2Se2
aFaculty of Chemistry and Chemical Engineering, “Babes-Bolyai” Univer-
sity, RO-400028, Cluj-Napoca, Romania. E-mail: ancas@chem.ubbcluj.ro;
Fax: +40 264 590818; Tel: +40 264 593833
bGroup of Biospectroscopy, “Petru Poni” Institute of Macromolecular
Chemistry, RO-700487, Iasi, Romania
Solid state and solution behavior
cNational NMR Laboratory, Institute of Organic Chemistry, Romanian
Academy, P.O. Box 35-98, RO-060023, Bucharest, Romania
In order to reveal the extent to which the nitrogen atom of the 2-
{E(CH2CH2)2NCH2}C6H4– group is coordinated to the selenium
center and the changes induced by the nature of the halogen atoms,
the molecular structures of compounds 1–3, 4·HBr, 5 and 6 were
determinated by single-crystal X-ray diffraction.
† Electronic supplementary information (ESI) available: Figures represent-
ing the supramolecular architectures in the crystals of compounds 2, 3,
1
4·HBr, 5 and 6; simulation of the aliphatic region of H NMR spectrum
of 3; variable temperature NMR data for 5; selected 15N and 77Se NMR
spectra. See DOI: 10.1039/b702629c
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The Royal Society of Chemistry 2007
Dalton Trans., 2007, 2187–2196 | 2187
©

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◦
˚
Table 1 Selected bond distances (A) and angles ( ) for compounds 1 and 2
1
2
Se(1)–Se(2)
Se(1)–C(1)
Se(1)–N(1)
N(1)–C(7)
N(1)–C(8)
N(1)–C(11)
O(1)–C(9)
O(1)–C(10)
2.3458(5)
1.940(4)
2.813(2)
1.434(5)
1.444(5)
1.452(5)
1.418(5)
1.402(5)
Se(1)–Se(2)
Se(1)–C(1)
Se(1)–N(1)
N(1)–C(7)
N(1)–C(8)
N(1)–C(11)
N(2)–C(9)
N(2)–C(10)
2.3700(5)
1.929(3)
3.135(3)
1.453(5)
1.445(5)
1.471(4)
1.450(5)
1.440(5)
1.451(5)
100.34(10)
71.05(11)
165.33(6)
75.1(2)
Se(2)–C(12)
Se(2)–N(2)
N(2)–C(18)
N(2)–C(19)
N(2)–C(22)
O(2)–C(20)
O(2)–C(21)
1.934(3)
2.825(3)
1.448(5)
1.450(4)
1.451(4)
1.390(5)
1.417(5)
Se(2)–C(13)
Se(2)–N(3)
N(3)–C(19)
N(3)–C(20)
N(3)–C(23)
N(4)–C(21)
N(4)–C(22)
N(4)–C(24)
C(13)–Se(2)–Se(1)
N(3)–Se(2)–C(13)
N(3)–Se(2)–Se(1)
Se(2)–N(3)–C(19)
Se(2)–N(3)–C(20)
Se(2)–N(3)–C(23)
C(19)–N(3)–C(20) 112.4(3)
C(19)–N(3)–C(23) 112.6(3)
C(20)–N(3)–C(23) 110.9(3)
1.937(3)
2.739(3)
1.469(5)
1.450(5)
1.452(4)
1.451(5)
1.444(5)
1.458(5)
101.13(11)
74.81(12)
171.89(7)
88.9(2)
N(2)–C(12)
C(1)–Se(1)–Se(2)
N(1)–Se(1)–C(1)
N(1)–Se(1)–Se(2)
Se(1)–N(1)–C(7)
Se(1)–N(1)–C(8)
Se(1)–N(1)–C(11)
C(7)–N(1)–C(8)
C(7)–N(1)–C(11)
C(8)–N(1)–C(11)
104.30(11)
74.95(12)
162.65(6)
89.2(2)
112.6(2)
118.3(2)
112.7(3)
113.2(3)
109.6(3)
C(12)–Se(2)–Se(1)
N(2)–Se(2)–C(12)
N(2)–Se(2)–Se(1)
Se(2)–N(2)–C(18)
Se(2)–N(2)–C(19)
Se(2)–N(2)–C(22)
C(18)–N(2)–C(19) 113.2(3)
C(18)–N(2)–C(22) 112.5(3)
C(19)–N(2)–C(22) 109.2(3)
104.45(10)
74.55(12)
166.39(5)
86.6(2)
112.0(2)
121.7(2)
C(1)–Se(1)–Se(2)
N(1)–Se(1)–C(1)
N(1)–Se(1)–Se(2)
Se(1)–N(1)–C(7)
Se(1)–N(1)–C(8)
Se(1)–N(1)–C(11)
C(7)–N(1)–C(8)
C(7)–N(1)–C(11)
C(8)–N(1)–C(11)
127.6(2)
116.7(2)
111.6(3)
110.2(3)
109.2(3)
109.8(2)
120.5(2)
C(9)–O(1)–C(10)
108.9(3)
C(20)–O(2)–C(21)
110.2(3)
C(9)–N(2)–C(10)
C(9)–N(2)–C(12)
C(10)–N(2)–C(12) 112.7(4)
109.1(3)
111.0(3)
C(21)–N(4)–C(22) 108.8(3)
C(21)–N(4)–C(24) 111.4(4)
C(22)–N(4)–C(24) 110.6(3)
The molecular structures of the diselenides 1 and 2 are shown
in Fig. 1 and 2 and the selected interatomic distances and
angles are listed in Table 1. In both compounds intramolecular
selenium–nitrogen interactions of significant strength are estab-
˚
˚
˚
˚
lished, i.e. Se(1) · · · N(1) 2.813(2) A, Se(2) · · · N(2) 2.825(3) A
for 1, and Se(1) · · · N(1) 3.135(3) A, Se(2) · · · N(3) 2.739(3) A
ꢀ
˚
for 2 [cf . the sums of the covalent radii,
rcov(Se,N) 1.87 A,
and of the corresponding van der Waals radii for selenium and
vdW(Se,N) 3.54 A]. These interatomic distances are
comparable with those observed in other related derivatives,
e.g. [2-(Me2NCH2)C6H4]2Se2 [2.856(3), 2.863(4) A], bis[2-(4,4-
dimethyl-2-oxazolinyl)phenyl]diselenide [2.819(5), 2.705(5) A].
ꢀ
9
˚
nitrogen,
r
8
˚
10,11
˚
The strong asymmetry of the Se–N bond lengths as observed
for 2 was suggested to be the result of steric effects.11 As a
result of the intramolecular N · · · Se interaction the coordination
geometry around the selenium atoms is distorted T-shaped
Fig. 2 ORTEP representation at 30% probability and atom numbering
scheme for the (RN1,SN3)-2 isomer. Hydrogen atoms are omitted.
[(C,N)SeSe core, hypervalent 10-Se-3 species12], with the vector
of the Se · · · N interaction directed almost trans to the Se–Se bond
[N(1) · · · Se(1)–Se(2) 162.65(6)◦, N(2) · · · Se(2)–Se(1) 166.39(5)◦
for 1, and N(1) · · · Se(1)–Se(2) 165.33(6)◦, N(3) · · · Se(2)–Se(1)
171.89(7)◦ for 2]. The coordination geometry around the Se atoms
can be alternatively described as pseudo-trigonal bipyramidal, with
N and the second Se atoms in axial positions and two lone pairs
and the carbon atom in the equatorial plane.
˚
˚
The Se(1)–Se(2) distance in 1 [2.3458(5) A] and 2 [2.3700(5) A]
is somewhat longer than those observed in other R2Se2 deriva-
11
˚
tives [2.29–2.39 A]. They are close to the Se–Se bond dis-
tances reported for related compounds [2-(Me2NCH2)C6H4]2Se2
8
˚
[2.357(1) A], and bis[2-(4,4-dimethyl-2-oxazolinyl)phenyl]-
10,11
˚
diselenide [2.354(8) A].
The conformation of the C–Se–Se–C skeleton can be discussed
in terms of “cisoid” (C–Se–Se–C torsion angle smaller than 90◦)
and “transoid” conformations (C–Se–Se–C torsion angle larger
than 90◦). The C–Se–Se–C torsion angle is 80.9◦ in 1 and 114.0◦
Fig. 1 ORTEP representation at 30% probability and atom numbering
scheme for the (RN1,SN2)-1 isomer.
2188 | Dalton Trans., 2007, 2187–2196
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in 2, thus consistent with a “cisoid” and a “transoid” arrangement,
respectively. The morpholinyl and piperazinyl rings exhibit a chair
conformation which prevents further intramolecular coordination
to the selenium centers.
The intramolecular coordination of the nitrogen from the pen-
dant arm to the selenium atom results in a five-membered SeC3N
ring. The ring is not planar but folded along the Se(1) · · · Cmethylene
axis, with the nitrogen atom lying out of the best plane defined by
the residual SeC3 system. This induces planar chirality [with the
aromatic ring and the nitrogen atom as chiral plane and pilot atom,
respectively]13 as described for other related compounds.6,14–18
Indeed, the diselenides reported here crystallize as racemates, i.e.
1 : 1 mixtures of (RN1,SN2) and (SN1,RN2) 1 and (RN1,SN3) and
(SN1,RN3) isomers for 2 (with respect to the two chelate rings in a
molecular unit).
While discrete molecules of the diselenide 1 are present in the
crystal (no contacts shorter than the sum of the van der Waals
radii between heavy atoms, or a heavy atom and H atoms), for the
diselenide 2 the crystal contains parallel chains built from either
(RN1,SN3) or (SN1,RN3) isomers connected through weak contacts
between the N(2) atom of a molecule and the aromatic H(3) atom
Fig. 3 ORTEP representation at 40% probability and atom numbering
scheme for the (S)-3 isomer.
The solid-state molecular structures of 3, 5 and 6 feature a
similar amine arm strongly coordinated to the selenium centre
trans to the selenium–halogen bond [N(1)–Se(1)–Cl(1) 175.92(6)◦
in 3; N(1)–Se(1)–I(1) 5, 174.52(7)◦; 6, 176.76(12)◦]. The decrease
in the electronegativity of the halogen is reflected in the strength
ꢀ
9
˚
˚
of a neighbouring molecule [2.675(3) A; cf .
r
vdW(N,H) 2.74 A ]
which extend along the b axis.
Single-crystals suitable for X-ray diffraction studies were ob-
tained from a CH2Cl2–n-hexane mixture for the halides 3, 5
and 6. Selected bond distances and angles are given in Table 2.
The compound 3 crystallizes in the chiral space group P212121
(orthorhombic) and therefore the investigated crystal contains
only the isomer S. The iodides 5 and 6 crystallize in monoclinic
P2(1)/n and P2(1)/c space groups, respectively, and crystals
contain 1 : 1 mixtures of R and S isomers. The ORTEP diagrams
for the (S)-3 and (R)-6 isomers are shown in Fig. 3 and 4.
˚
of the internal Se · · · N interactions [Se(1)–N(1) 3, 2.204(2) A; 5,
˚
˚
2.291(3) A; 6, 2.282(4) A], which are somewhat weaker than in the
5
˚
related [2-(Me2NCH2)C6H4]SeX derivatives [Se–N 2.135(4) A,
6
5
6
˚
˚
˚
2.137(2) A, for X = Cl; 2.172(3) A, 2.167(3) A, for X =
I]. As expected for a 3c–4e system, the linear arrangement of
the N · · · Se–X unit results in the elongation of the Se–halogen
˚
˚
bonds [Se(1)–Cl(1) 2.4270(8) A in 3; Se(1)–I(1) 5, 2.7252(5) A; 6,
˚
2.7148(8) A] as observed in the related [2-(Me2NCH2)C6H4]SeX
◦
˚
Table 2 Selected bond distances (A) and angles ( ) for compounds 3, 4·HBr, 5 and 6
3
4·HBr
5
6
Se(1)–C(1)
Se(1)–Cl(1)
1.929(2)
2.4270(8)
Se(1)–C(1)
Se(1)–Br(1)
Se(1)–Br(2)
1.934(8)
2.4389(18)
2.8043(15)
Se(1)–C(1)
Se(1)–I(1)
1.930(3)
2.7252(5)
Se(1)–C(1)
Se(1)–I(1)
1.928(6)
2.7148(8)
Se(1)–N(1)
2.204(2)
Se(1)–N(1)
2.291(3)
Se(1)–N(1)
2.282(4)
N(1)–H(2)
Br(2)–H(2)
Br(2)–H(2)–N(1)
N(1)–C(7)
N(1)–C(8)
N(1)–C(11)
O(1)–C(9)
0.84(7)
2.555(7)
163(6)
1.501(11)
1.481(11)
1.492(12)
1.402(12)
1.398(11)
N(1)–C(7)
N(1)–C(8)
N(1)–C(11)
O(1)–C(9)
O(1)–C(10)
1.478(3)
1.480(3)
1.490(3)
1.423(3)
1.428(3)
N(1)–C(7)
N(1)–C(8)
N(1)–C(11)
O(1)–C(9)
O(1)–C(10)
1.470(5)
1.481(5)
1.484(5)
1.415(5)
1.418(5)
N(1)–C(7)
N(1)–C(8)
1.471(8)
1.479(7)
1.465(7)
1.459(9)
1.455(9)
1.461(9)
98.18(17)
80.4(2)
N(1)–C(11)
N(2)–C(9)
N(2)–C(10)
N(2)–C(12)
C(1)–Se(1)–I(1)
C(1)–Se(1)–N(1)
N(1)–Se(1)–I(1)
O(1)–C(10)
C(1)–Se(1)–Cl(1)
C(1)–Se(1)–N(1)
N(1)–Se(1)–Cl(1)
95.07(8)
81.33(9)
175.92(6)
C(1)–Se(1)–Br(1)
93.9(2)
C(1)–Se(1)–I(1)
C(1)–Se(1)–N(1)
N(1)–Se(1)–I(1)
97.24(11)
79.58(13)
174.52(7)
176.76(12)
C(1)–Se(1)–Br(2)
Br(1)–Se(1)–Br(2)
85.4(2)
177.34(6)
Se(1)–N(1)–C(7)
Se(1)–N(1)–C(8)
Se(1)–N(1)–C(11)
C(7)–N(1)–C(8)
C(7)–N(1)–C(11)
C(8)–N(1)–C(11)
C(9)–O(1)–C(10)
102.87(15)
111.06(15)
110.80(14)
110.7(2)
111.8(2)
109.53(19)
109.88(19)
Se(1)–N(1)–C(7)
Se(1)–N(1)–C(8)
Se(1)–N(1)–C(11)
C(7)–N(1)–C(8)
C(7)–N(1)–C(11)
C(8)–N(1)–C(11)
C(9)–O(1)–C(10)
99.8(2)
111.9(2)
112.3(2)
111.4(3)
112.3(3)
109.0(3)
110.2(3)
Se(1)–N(1)–C(7)
Se(1)–N(1)–C(8)
Se(1)–N(1)–C(11)
C(7)–N(1)–C(8)
C(7)–N(1)–C(11)
C(8)–N(1)–C(11)
C(9)–N(2)–C(10)
C(9)–N(2)–C(12)
C(10)–N(2)–C(12)
100.9(3)
112.2(4)
110.5(4)
111.5(5)
110.7(5)
110.6(5)
108.4(5)
111.3(6)
110.8(7)
C(7)–N(1)–C(8)
C(7)–N(1)–C(11)
C(8)–N(1)–C(11)
C(9)–O(1)–C(10)
112.0(8)
112.8(7)
109.7(7)
111.8(8)
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As for the diselenides 1 and 2, in the halides 3, 4·HBr, 5 and 6 the
morpholinyl and piperazinyl rings exhibit a chair conformation
which prevents further intramolecular coordination of the O(1)
or the N(2) atom to the selenium center and thus a (C,N,Y)-
monometallic triconnective pattern (Y = O, N) of the organic
ligand.
Within the molecule of the chloride 3 and the iodides 5 and 6
there are interactions between the halogen atom and the proton
˚
ortho to selenium in the organic ligand [Cl(1) · · · H(6) 2.67 A in
˚
˚
3; I(1) · · · H(6) 2.96 A and 2.87 A in 5 and 6, respectively; cf .
ꢀ
ꢀ
9
˚
˚
r
vdW(Cl,H) 3.01 A,
rvdW(I,H) 3.35 A ].
In the crystals of 3, 4·HBr and 6 the discrete molecular units are
separated by normalvander Waals distances between heavyatoms.
A closer inspection of the crystal structures revealed different
supramolecular architectures built through weak intermolecular
interactions which involve hydrogen atoms. Thus, for the chloride
3 chains of S isomers are formed through Cl(1) · · · H(7Bb)methylene
Fig. 4 ORTEP representation at 40% probability and atom numbering
scheme for the (R)-6 isomer.
ꢀ
9
˚
˚
contacts [2.89 A; cf .
r
vdW(Cl,H) 3.01 A ], which are further asso-
ciated into layers through weak O(1) · · · H(7Abꢀ)methylene (2.50 A)
˚
5
6
5
˚
˚
˚
ꢀ
derivatives [Se–Cl 2.4757(7) A, 2.471(2) A; Se–I 2.8227(4) A,
and O(1) · · · H(11Abꢀ)N-methylene-ring [2.56 A; cf .
r
vdW(O,H) 2.60 A ]
9
˚
˚
6
˚
2.8079(7) A ]. They are considerably longer than those observed
(Fig. 6).
19
20
˚
˚
for [2,4,6-Me3C6H2]SeX [Se–Cl 2.186(1) A, Se–I 2.529(1) A ].
The strong intramolecular coordination of the nitrogen atom
to the selenium centre results in a distorted T-shaped (C,N)SeX
core (X = Cl, I; hypervalent 10-Se-3 species12) in compounds 3, 5
and 6, respectively. The deviation from the ideal N–Se–X angle of
180◦ is due to the constraints imposed by the coordinated amine
arm.
Attempts to grow crystals of the bromide 4 resulted in isolation
of the adduct RSeBr·HBr (4·HBr), probably obtained by partial
hydrolysis of the compound. Selected bond distances and angles
are given in Table 2. The molecular structure determination re-
vealed that the nitrogen atom of the pendant arm is protonated [the
H(2) atom was localised from the electron density map]. The Br(2)
˚
atom is bonded to the selenium center [Se(1)–Br(2) 2.8043(15) A]
in trans to the Br(1) atom [Br(1)–Se(1)–Br(2) 177.34(6)◦] (Fig. 5),
which results in a considerable shortening of the Se(1)–Br(1)
˚
bond [2.4389(18) A] in comparison to the value found for the
8
˚
related [2-(Me2NCH2)C6H4]SeBr [2.634(1) A ]. A hydrogen bond
˚
Br(2) · · · H(2) [2.555(7) A] is established intramolecularly. The
adduct can be described as a zwitterionic compound of the type [2-
{O(CH2CH2)2N+(H)CH2}C6H4]Se−Br2, with a distorted T-shaped
CSeBr2 core.
Fig. 6 View of the layer network based on intermolecular hydrogen
contacts (only hydrogens involved in intermolecular interactions are
shown) in the crystal of 3 [symmetry equivalent atoms (−0.5 + x, 0.5 − y,
−z), (0.5 + x, 0.5 − y, −z), (−0.5 + x, −0.5 − y, −z) and (0.5 + x, −0.5 −
y, −z) are given by “a”, “b”, “a prime” and “b prime”].
Significant differences are observed for the iodides 5 and 6. In
the crystal of 5 dimers of R and S isomers are formed through inter-
ꢀ
ꢀ
˚
˚
molecular Se(1) · · · I(1 ) [3.957(1) A] and I(1) · · · H(9B ) (3.28 A)
ꢀ
ꢀ
9
˚
˚
rvdW(I,H) 3.35 A ]. The
interactions [cf .
r
vdW(Se,I) 4.15 A,
dimers are associated through inter-dimer I(1) · · · H(5aꢀ) inter-
˚
actions (3.29 A) into columnar chain polymers (Fig. 7a) which
extend along the c axis. Further contacts between the mor-
pholinyl oxygens and methylene protons [O(1) · · · H(7B) 2.51 A]
Fig. 5 ORTEP representation at 40% probability and atom numbering
scheme for 4·HBr.
˚
2190 | Dalton Trans., 2007, 2187–2196
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The NMR spectra for compounds 1–6 were recorded in CDCl3,
at room and low temperature (−50 to +40 ◦C), or in C6D6, at room
and high temperature (+26 to +79 ◦C). The assignment of the 1H
and 13C chemical shifts was made according to the numbering
schemes (a) and (b) (Scheme 2), respectively. These assignments
1
are based on 2D experiments. For compounds 1 and 2, the H
chemical shifts and the multiplicity of the signals belonging to
the H-3, H-4, and H-5 atoms in the aromatic ring, could not
be obtained from the 1H-NMR spectra. Therefore, in these cases
the relevant data have been obtained as 1D traces from the H,C-
undecoupled-HSQC spectra.21 Fig. 9 exemplifies such assignments
in the spectrum of compund 1.
Scheme 2
Fig. 7 (a) View of the columnar chain polymer in the crystal of 5
based on hydrogen contacts between dimer units. (b) View along the
c axis of the tridimensional network built from columnar chain polymers
in the crystal of 5, through oxygen–hydrogen inter-chain contacts (only
hydrogens involved in hydrogen contacts are shown).
ꢀ
˚
rvdW(O,H) 2.60 A) of adjacent chain polymers result in a
(cf .
tridimensional network (Fig. 7b). By contrast, the crystal of 6
contains chain polymers in which alternating S and R isomers are
˚
connected through weak intermolecular I(1) · · · H(11Bb) (3.31 A)
interactions (Fig. 8) and no further inter-chain contacts are
established.
Fig. 8 View along the a axis of the chain polymer of alternating S and
R isomers in the crystal of 6 (only hydrogens involved in intermolecular
contacts are shown).
The crystal of the adduct 4·HBr also exhibits a tridimensional
architecture based on weak hydrogen contacts. Contacts between
bromine atoms and aryl and morpholinyl ring hydrogen atoms
Fig. 9 (a) The 1H-NMR spectrum of compound 1; HSQC traces extracted
at the resonance frequencies for 13C atoms in (b) C-4, (c) C-5, and (d) C-3
positions, respectively. The traces are displayed for the region around the
low field 13C satellite in the 1H dimension.
ꢀꢀ
ꢀꢀ
˚
˚
[Br(1) · · · H(11B ) 3.02 A, Br(2) · · · H(8Aa) 3.05 A, Br(2) · · · H(4 )
˚
3.06 A] result in a layer which extends along the c axis. Inter-layer
contacts which involve the morpholinyl oxygen atoms and aryl
ꢀ
˚
protons [O(1) · · · H(5 ) 2.37 A] led to the tridimensional network
The NMR data provide evidence for the presence of the
intramolecular N → Se interaction in solution. The strongest
(see ESI†).
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evidence for such an interaction is provided by the H,Se-HMBC
spectra. In these spectra there are strong cross peaks for the Se–
H-8,11 and Se–H-9,10 resonances. It would be very difficult to
admit such a through bond correlation between Se and H-9,10 (J
coupling over seven bonds) in the absence of a Se–N bonding. The
presence of the Se–N bonding reduces the Se–H-9,10 correlation
to a J coupling over four bonds.
intramolecular N → Se interaction the H-8,11 and H-9,10 protons
became non-equivalent, i.e. pro-cis [Ha (equatorial) and Hd (axial)
in Scheme 3, A] and pro-trans [Hb (axial) and Hc (equatorial) in
Scheme 3, A] with respect to the position of the selenium atom in
relation to the morpholinyl ring.
New RSe–SeR (R = 2-[O(CH2CH2)2NCH2]C6H4, 2-[MeN-
(CH2CH2)2NCH2]C6H4) and RSeX (X = Cl, Br, I) were inves-
tigated in solution and the solid state. Evidence for the N →
Se interactions in solution were obtained from NMR studies.
In all cases T-shaped coordination geometries, i.e. (C,N)SeSe,
(C,N)SeX (X = halogen) or CSeBr2, were found in the solid
state. Supramolecular associations in crystals based on hydrogen
contacts are discussed.
1
The alkyl region in the room-temperature H NMR spectrum
for the diselenide 1 exhibits two resonances for the H-8,11 and
H-9,10 protons of the pendant arm ring. A similar pattern was ob-
served for the free organic ligands [O(CH2CH2)2NCH2]C6H5 and
[2-{O(CH2CH2)2NCH2}]C6H4Br.22 This suggests a considerable
weakness of the intramolecular N → Se interaction which allows
a fast conformational change of the six-membered morpholinyl
ring in the molecule of 1.
The most upfield shifted 1H signal (d 2.68 ppm for 3 and
2.64 ppm for 4) was assigned to pro-trans-H-8,11 (Hb) protons.
It is split due to the proton–proton coupling with the geminal pro-
cis-H-8,11 (Ha) protons, as well as the pro-cis-H-9,10 (Hd) and
pro-trans-H-9,10 (Hc) protons of the neighbouring CH2 group.
The resonance due to the pro-cis-H-8,11 (Ha) protons is more
deshielded (d 3.12 ppm for 3 and 3.10 ppm for 4) due to the prox-
imity of the electronegative SeCl moiety. Only the coupling with
the geminal proton is observed in this case. It is worthwhile to note
here that the 1H NMR spectra of [2-{O(CH2CH2)2NCH2}C6H4]Li
and [2-{O(CH2CH2)2NCH2}C6H4]Ti(Cp)Cl2 (−50 ◦C, in toluene-
d6) were reported to exhibit a similar pattern.22
By contrast, at +26 ◦C, the 1H spectra in CDCl3 for the halides
3–5 exhibit a different pattern, i.e. three resonances—a multiplet
(4H) for the H-9,10 protons (–CH2–CH2–O), and a doublet
(2H) and a doublet of doublets of doublets (2H) for the H-8,11
protons (N–CH2–CH2). The non-equivalence of the protons in
the N–CH2–CH2 groups (H-8,11) is consistent with the presence
of the intramolecular N → Se interaction in solution, at room
temperature, as found in the solid state. Such an interaction will
prevent the fluxional behaviour A → B described in Scheme 3,
which would result in equivalent protons in the N–CH2–CH2 and
–CH2–CH2–O groups, respectively, following a process sequence
which involves N → Se disscociation/Ar–CH2(N) bond rota-
tion/N inversion/Ar–CH2(N) bond rotation/(Ar)CH2–N bond
rotation/N → Se asscociation/morpholinyl ring conformation
change [exchange of the (Ar)CH2–N bond from axial to equatorial
position with respect to the six membered ring]. As result of the
1
For the iodide 5 the room temperature H NMR spectrum in
CDCl3 exhibits two broad singlets for H-8,11 protons (coales-
cence), but at −30 ◦C the pattern of the alkyl region becomes
similar to that observed for the chloride 3 and the bromide 4, at
room temperature.
The solution behavior of the iodide 6 at room temperature is
similar to that of the iodide 5 (three unresolved broad signals for
1
H-9,10 and H-8,11 protons in the H NMR spectrum), while at
−40 ◦C the resonances are resolved, i.e. a triplet for all four H-9,10
protons, and an AB system for the pro-trans-H-8,11 and pro-cis-
H-8,11 protons. This behavior is consistent with a similar fluxional
process as described above for the morpholinyl analogs.
The 15N chemical shifts are considerably dependent on the
electron delocalization of the nitrogen lone pair23 and are thus
useful for estimation of the intramolecular N → Se interactions.
For compounds 1–6 the 15N chemical shifts (Table 3) follow
the trend observed for the related compounds containing the
[2-(CyMeNCH2)C6H4]Se fragment,24 i.e. the dN for the NCH2
Scheme 3
Table 3 15N and 77Se chemical shifts for compounds 1–6 and the corresponding Se–N distances (single-crystal X-ray data)
15N NMR dN (ppm)
77Se NMR dSe (ppm)
Se–N distance/A
˚
Compound
1
2
50.6a
424.0a
425.4a
428.8b
945.0a
892.1a
702.0a
687.7b
691.2c
2.813(2)/2.825(3)
3.135(3)/2.739(3)
38.6 (NMe)a
37.3 (NMe), 50.9 (NCH2)b
3
4
5
66.9a
2.204(2)
2.291(3)
68.6a
64.8a
63.1b
63.1c
61.1d
677.3d
e
6
38.0 (NMe), 67.0 (NCH2)a
37.4 (NMe), 65.5 (NCH2)b
35.3 (NMe), 63.4 (NCH2)d
2.282(4)
e
700.0b
a At +26 ◦C, in CDCl3. b At +60 ◦C, in CDCl3. c At +26 ◦C, in C6D6. d At +65 ◦C, in C6D6. e Not observed.
2192 | Dalton Trans., 2007, 2187–2196
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nitrogen in the halides 3–6 is shifted downfield with respect to
the corresponding diselenides 1 and 2, consistent with the increase
in the strength of the N → Se interaction. It should be mentioned
here that for compound 2 the two expected 15N resonances could be
observed only at +60 ◦C, in CDCl3, while at room temperature the
H,N-HMBC spectrum exhibited only the resonance (d 38.6 ppm)
for the NMe nitrogen. This is due to the continuous variation
of the H–N coupling constants on the time scale of the NMR
experiment. Thus, the only visible cross peak at room temperature
is for N–H-12 (in the NMe group) for which the coupling constant
remains unchanged during the ring inversion.
between R- and S-5 isomers are formed through intermolecular
Se · · · I interactions. For all compounds, except 1, supramolecular
architectures are built through intermolecular contacts between
hydrogen atoms and heavier electronegative (halogen, oxygen)
atoms.
Experimental
General procedures
Most of the 1D and all of the 2D NMR spectra have been recorded
in dried solvents on a Bruker Avance DRX 400 instrument,
equipped with a 5 mm multinuclear inverse detection z-gradient
probehead, operating at 400.1, 100.6, 46.5, and 76.3 MHz for
The 77Se chemical shifts for compounds 1–6 (Table 3) are
also consistent with the presence of the intramolecular N → Se
interaction in solution. The 77Se chemical shifts for the diselenides
1 (424.0 ppm) and 2 (425.4 ppm) are of the same magnitude
as reported for the related [2-(Me2NCH2)C6H4]2Se2 (430 ppm),8
[2-(CyMeNCH2)C6H4]2Se2 (431.9 ppm),24 and R2Se2 (454.8 ppm;
R = 2-(4,4-dimethyl-2-oxazolinyl)phenyl).11 A large deshielding is
observed for the halides 3–6 with respect to the diselenides 1 and
2. The trend followed by the dSe, in CDCl3 at room temperature,
is RSeCl (3) (944.7 ppm) > RSeBr (4) (893.4 ppm) > RSeI
(5) (702.0 ppm), consistent with the increased deshielding of
the selenium resonances as the electronegativity of the attached
substituent increases.25 A similar trend for the 77Se resonances was
reported for [2-(Me2NCH2)C6H4]SeX (dSe 1030 ppm, X = Cl;5
987 ppm, X = Br;8 818 ppm, X = I8), [2-(CyMeNCH2)C6H4]SeX
(dSe 1051.3 ppm, X = Cl; 1011.2 ppm, X = Br)24 or RSeX
[R = 2-(4,4-dimethyl-2-oxazolinyl)phenyl] (dSe 855.9 ppm, X =
Cl; 849.5 ppm, X = Br; 762.2 ppm, X = I),11 for which the
presence of the internal N → Se interaction in solution was well
documented by multinuclear NMR studies. For compound 6 the
77Se resonance in the H,Se-HMBC spectrum could be observed
only at +65 ◦C, in C6D6. The same explanation as in the case
of the N,H-HMBC spectrum discussed above, holds true. The
differences in the values reported for the 77Se chemical shifts
indicates that, in addition to the effect of the halogen atom, the
nature of the organic group attached to selenium can exhibit a
considerable contribution and this effect should be considered
when comparisons are made between NMR parameters observed
for different series of compounds.
1
1H, 13C, 15N, and 77Se nuclei, respectively. Low temperature H
NMR spectra for 5 and 6 were recorded on a Bruker Avance
1
300 spectrometer operating at 300.1 MHz. H and 13C chemical
shifts are reported in d units (ppm) relative to the residual peak of
solvent (ref.: CHCl3, 1H, 7.26 ppm; CDCl3, 13C, 77.0 ppm; C6H6,
1H, 7.16 ppm; C6D6, 13C, 128.06 ppm). H,H-COSY, H,C-HSQC
and H,C-HMBC experiments, were recorded using standard pulse
sequences in the version with z-gradients, as delivered by Bruker
with TopSpin 1.3 PL6 spectrometer control and processing soft-
ware. H,C-undecoupled-HSQC experiments have been recorded
using the pulse sequence described by Simova.21 The 15N chemical
shifts were obtained as projections from the 2D indirectly detected
H,N-HMBC spectra, using a standard pulse sequence in the
version with z-gradients as delivered by Bruker (TopSpin 1.3
PL6) and are referred to external liquid ammonia (0.0 ppm)
using as external standard nitromethane (380.2 ppm). The 77Se
chemical shifts were obtained as projections from the 2D indirectly
detected H,Se-HMBC spectra, using a standard pulse sequence
in the version with z-gradients (60 : 20 : 55.3% gradient ratios)
and are referred to external dimethylselenide (0.0 ppm) using
as external standard dimethyldiselenide (275.0 ppm).26 Elemental
analyses were performed by Facultatea de Farmacie, Universitatea
de Medicina si Farmacie “Iuliu Hatieganu”, Cluj-Napoca (Roma-
nia). All manipulations were carried out under an inert atmosphere
of argon (Linde, 99.999%) using Schlenk techniques. Solvents were
dried and freshly distilled under argon prior to use. Selenium and
butyllithium (1.6 M in hexane) were commercially available. The
organic bromides used as starting materials were prepared accord-
ing to the published methods: 2-[O(CH2CH2)2NCH2]C6H4Br,22 2-
[MeN(CH2CH2)2NCH2]C6H4Br.27
Conclusions
New diselenides, R2Se2, and halides, RSeX, containing the [2-
{E(CH2CH2)2NCH2}C6H4] (E = O, NMe) moieties were prepared
and their hypervalent nature was investigated both in solution
and in the solid state. The H,Se-heteronuclear NMR correlations
provided evidence for the presence of the intramolecular N →
Se interaction in solution for the organoselenium compounds
investigated in this work. The variable temperature NMR data
suggest that these interactions in solution are stronger for the
organoselenium(II) chloride and bromide, and weaker in the cases
of the iodides and diselenide derivatives. In the solid state all inves-
tigated compounds exhibit a T-shaped coordination geometry, i.e.
(C,N)SeSe for [2-{E(CH2CH2)2NCH2}C6H4]2Se2 [E = O (1), NMe
(2)], (C,N)SeX for the halides [2-{E(CH2CH2)2NCH2}C6H4]SeX
[E = O, X = Cl (3), I (5); E = NMe, X = I (6)], or CSeBr2 for [2-
{O(CH2CH2)2NCH2}C6H4]SeB·HBr (4·HBr). Discrete molecules
are present in the crystal of the diselenide 1. Dimer associations
Syntheses
Synthesis of [2-{O(CH2CH2)2NCH2}C6H4]2Se2 (1). A solu-
tion of BuLi in hexane (6.4 mL, 1.6 M, 10.0 mmol) was added
dropwise, at room temperature, under argon to a stirred solution
of 2-[O(CH2CH2)2NCH2]C6H4Br (2.561 g, 10.0 mmol) in 100 mL
anhydrous diethyl ether. The reaction mixture was stirred at room
temperature for 24 h, when a white slurry of the lithiated product
was obtained. Elemental selenium powder (0.79 g, 10.0 mmol) was
added under argon and the stirring was continued for 0.5 h. The
resulting yellowish solution was poured into a beaker containing
saturated aqueous NaHCO3 (100 mL) and left overnight in an
efficient fume hood to effect complete oxidation. The compound
was extracted with methylene dichloride (3 × 50 mL) and the
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combined organic phases were dried over anhydrous Na2SO4.
The solvent was removed under vacuum to give a yellow oil. The
oily product was dissolved in the minimum amount of anhydrous
diethyl ether (5 mL), layered with hexane and kept at −28 ◦C. After
a few weeks the title compound 1 separated as a yellow, crystalline
solid which was filtered off and dried under vacuum (1.6 g, 63%),
mp 96–98 ◦C. Anal. Calcd for C22H28N2O2Se2 (510.40): C, 51.77;
8.09 (1 H, d, H-6, C6H4, 3JHH 8.0 Hz). 13C NMR (CDCl3, +26 ◦C):
d 54.41 (s, C-8,11), 65.12 (s, C-7), 65.26 (s, C-9,10), 125.63 (s, C-3),
126.34 (s, C-4), 129.12 (s, C-5), 129.17 (s, C-6), 133.87 (s, C-2),
136.23 (s, C-1).
Synthesis of [2-{O(CH2CH2)2NCH2}C6H4]SeBr (4). A solu-
tion of compound 1 (0.41 g, 0.8 mmol) in 50 mL CHCl3 was
treated dropwise with a solution of bromine (0.128 g, 0.8 mmol)
in 10 mL CHCl3, at 0 ◦C. The reaction mixture was stirred at 0 ◦C
for additional 2 h, then it was allowed to reach room temperature
and the solvent was removed under vacuum. The resulting solid
was washed with hexane. Recrystallization from CH2Cl2–n-hexane
(1:5, v/v) gives the title compound as yellow crystals (0.37 g,
1
H, 5.53; N, 5.49; Found: C 51.55; H, 5.43; N, 5.27%. H NMR
(CDCl3, +26 ◦C): d 2.50 (8 H, s,br, H-8,11, N–CH2–CH2–O), 3.61
(4 H, s, H-7, C6H4–CH2–N), 3.72 (8 H, t, H-9,10, N–CH2–CH2–O,
3JHH 4.6 Hz), 7.07–7.20 (6 H, m, C6H4) [resolved in HSQC as: 7.16
3
3
(2 H, t, H-4, JHH 7.1 Hz), 7.19 (2 H, d, H-3, JHH 7.1 Hz), 7.19
(2 H, t, H-5, 3JHH 7.1 Hz)], 7.80 (2 H, dt, H-6, C6H4, 3JHH 6.4, 4JHH
1.6 Hz). 13C NMR (CDCl3, +26 ◦C): d 52.50 (s, C-8,11), 63.65 (s,
C-7), 67.00 (s, C-9,10), 125.86 (s, C-4), 128.34 (s, C-5), 128.79 (s,
C-3), 131.50 (s, C-6), 134.07 (s, C-1), 138.10 (s, C-2).
◦
69%), mp 167–169 C. Anal. Calcd for C11H14BrNOSe (335.10):
C, 39.43; H, 4.21; N, 4.18; Found: C, 39.45; H, 4.11; N, 3.97%.
◦
1H NMR (CDCl3, +26 C): d 2.65 (2 H, ddd, pro-trans-H-8,11,
2
3
3
N–CH2–CH2–O, JHH 12.6, JHH 9.7, JHH 5.2 Hz), 3.10 (2 H, d,
pro-cis-H-8,11, N–CH2–CH2–O, 2JHH 12.7 Hz), 3.89 (2 H, s, H-7,
C6H4–CH2–N), 3.91 (4 H, m, H-9,10, N–CH2–CH2–O), 7.13 (1 H,
d, br, H-3, C6H4, 3JHH 8.0 Hz), 7.21 (1 H, td, H-4, C6H4, 3JHH 7.4,
4JHH 1.0 Hz), 7.32 (1 H, td, H-5, C6H4, 3JHH 8.4, 4JHH 1.4 Hz), 8.12
Synthesis of [2-{MeN(CH2CH2)2NCH2}C6H4]2Se2 (2). A so-
lution of BuLi in hexane (3.50 mL, 1.6 M, 5.6 mmol) was added
dropwise, at room temperature, under argon to a stirred solution
of 2-[MeN(CH2CH2)2NCH2]C6H4Br (1.51 g, 5.6 mmol) in 100 mL
anhydrous hexane. The reaction mixture was stirred, under reflux,
for 4 h and then allowed to reach room temperature. Evaporation
of the solvent gave [2-{MeN(CH2CH2)2NCH2}C6H4]Li as a white
compound. The solid was dissolved in 100 mL anhydrous THF,
elemental selenium powder (0.44 g, 5.6 mmol) was added and the
reaction mixture was stirred for 1 h at room temperature, under
argon. The resulting yellowish solution was poured into a beaker
containing saturated aqueous NaHCO3 (100 mL) The compound
was extracted with methylene dichloride (3 × 50 mL) and the
combined organic phases were dried over anhydrous Na2SO4.
Removal of the solvent under vacuum gives 2 (0.6 g, 40%) as
a yellow solid, mp 111–113 ◦C. Anal. Calcd for C24H34N4Se2
(536.48): C, 53.73; H, 6.39; N, 10.44; Found: C, 53.51; H, 6.12;
3
4
(1 H, dd, H-6, C6H4, JHH 8.0, JHH 0.4 Hz). 13C NMR (CDCl3,
+26 ◦C): d 54.18 (s, C-8,11), 65.02 (s, C-7), 65.60 (s, C-9,10), 125.83
(s, C-3), 126.50 (s, C-4), 129.33 (s, C-5), 131.54 (s, C-6), 134.21 (s,
C-1), 134.45 (s, C-2).
Synthesis of [2-{O(CH2CH2)2NCH2}C6H4]SeI (5). A solution
of compound 1 (0.51 g, 1.0 mmol) in 20 mL CHCl3 was treated
dropwise with a solution of iodine (0.254 g, 1.0 mmol) in 40 mL
CCl4, at 0 ◦C. The reaction mixture was stirred at 0 ◦C for an
additional 2 h, then it was allowed to reach room temperature and
the solvent was removed under vacuum. The resulting solid was
washed with hexane. Recrystallization from CH2Cl2–n-hexane (1 :
5, v/v) gives the title compound as red crystals (0.53 g, 69%),
mp 136–137 ◦C. Anal. Calcd for C11H14INOSe (382.10): C, 34.58;
N, 10.24%. H NMR (CDCl3, +26 ◦C): d 2.30 (6 H, s, NCH3),
1
1
2.49, 2.54 (16 H, br, H-8,9,10,11, N–CH2–CH2–N) (at +60 ◦C, this
resonance is resolved into 2 broad doublets at 2.48 and 2.54 ppm
for H-9,10 and H-8,11, respectively), 3.62 (4 H, s, H-7, C6H4–CH2–
N), 7.07–7.18 (6 H, m, C6H4) [resolved in HSQC as: 7.11 (2 H, t,
H, 3.69; N, 3.67; Found: C, 34.37; H, 3.49; N, 3.53%. H NMR
◦
◦
(CDCl3, +26 C): d 2.49–2.91 (4 H, br, H-8,11) (at +60 C, this
resonance appears as a singlet at 2.69 ppm), 3.72 (2 H, s, H-7,
3
C6H4–CH2–N), 3.86 (4 H, t, H-9,10, N–CH2–CH2–O, JHH 4.8
Hz), 7.06 (1 H, d, br, H-3, C6H4, 3JHH 6.8 Hz), 7.20 (1 H, td, H-4,
3
3
H-4, JHH 7.4 Hz), 7.14 (2 H, d, H-3, JHH 7.4 Hz), 7.14 (2 H, t,
H-5, 3JHH 7.4 Hz)], 7.80 (2 H, dd, H-6, C6H4, 3JHH 7.8, 4JHH 1.4 Hz).
13C NMR (CDCl3, +26 ◦C): d 45.89 (s, NCH3), 51.91 (s, C-8,11),
55.01 (s, C-9,10), 63.19 (s, C-7), 125.74 (s, C-4), 128.21 (s, C-5),
128.64 (s, C-3), 131.41 (s, C-6), 134.12 (s, C-1), 138.55 (s, C-2).
3
4
3
C6H4, JHH 7.3, JHH 1.3 Hz), 7.25 (1 H, td, H-5, C6H4, JHH 7.6,
4JHH 1.6 Hz), 8.05 (1 H, dd, H-6, C6H4, JHH 7.8, JHH 1.4 Hz).
3
4
◦
1H NMR (CDCl3, −30 C): d 2.47 (2 H, ddd, pro-trans-H-8,11,
N–CH2–CH2–O, 2JHH 12.1, 3JHH 10.4, 3JHH 4.2 Hz), 2.95 (2 H, d,
pro-cis-H-8,11, N–CH2–CH2–O, 2JHH 12.4 Hz), 3.72 (2 H, s, H-7,
C6H4–CH2–N), 3.82 (4 H, m, H-9,10, N–CH2–CH2–O), 7.04 (1 H,
dd, H-3, C6H4, 3JHH 6.5, 4JHH 1.8 Hz), 7.18 (2 H, m, H-4,5, C6H4),
7.98 (1 H, dd, H-6, C6H4, 3JHH 7.1, 4JHH 1.8 Hz). 13C NMR (CDCl3,
+26 ◦C): d 53.42 (s, C-8,11), 64.34 (s, C-7), 66.05 (s, C-9,10), 126.42
(s, C-3), 126.52 (s, C-4), 129.27 (s, C-5), 130.41 (s, C-1), 135.90 (s,
C-6), 136.11 (s, C-2).
Synthesis of [2-{O(CH2CH2)2NCH2}C6H4]SeCl (3). A solu-
tion of compound 1 (1.108 g, 2.17 mmol) in 100 mL CCl4 was
treated dropwise with a solution of SO2Cl2 (0.293 g, 2.17 mmol)
in 100 mL CCl4, at room temperature. The reaction mixture was
stirred for 4 h, then the resulting solid was filtered off and washed
with hexane. Recrystallization from CH2Cl2–n-hexane (1 : 5, v/v)
gives the title compound as pale yellow crystals (0.88 g, 70%), mp
152–154 ◦C. Anal. Calcd for C11H14ClNOSe (290.65): C, 45.46;
Synthesis of [2-{MeN(CH2CH2)2NCH2}C6H4]SeI (6). A solu-
tion of compound 2 (0.5 g, 0.93 mmol) in 100 mL CCl4 was treated
dropwise with a solution of iodine (0.23 g, 0.93 mmol) in 100 mL
CCl4, at room temperature. The reaction mixture was stirred for
4 h, then the red solution was concentrated under vacuum until
a red solid deposited. The solid was filtered off and was washed
with hexane. Recrystallization from CH2Cl2–n-hexane (1 : 5, v/v)
gives the title compound as red crystals (0.50 g, 68%), mp 160 ◦C
1
H, 4.86; N, 4.82; Found: C 45.26; H, 4.75; N, 4.91%. H NMR
(CDCl3, +26 ◦C): d 2.69 (2 H, ddd, pro-trans-H-8,11, N–CH2–
CH2–O, 2JHH 12.5, 3JHH 10.7, 3JHH 4.3 Hz), 3.12 (2 H, d, pro-cis-
2
H-8,11, N–CH2–CH2–O, JHH 11.6 Hz), 3.90 (4 H, m, H-9,10,
N–CH2–CH2–O), 3.94 (2 H, s, H-7, C6H4–CH2–N), 7.17 (1 H, dd,
H-3, C6H4, 3JHH 7.2, 4JHH 1.2 Hz), 7.20 (1 H, td, H-4, C6H4, 3JHH
7.3, 4JHH 0.9 Hz), 7.35 (1 H, td, H-5, C6H4, 3JHH 7.6, 4JHH 1.6 Hz),
2194 | Dalton Trans., 2007, 2187–2196
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Table 4 Crystallographic data for compounds 1–3, 4·HBr, 5 and 6
1
2
3
4·HBr
5
6
Empirical formula
M
T/K
C22H28N2O2Se2
510.38
297(2)
C24H34N4Se2
536.47
297(2)
C11H14ClNOSe
290.64
297(2)
C11H15Br2NOSe
416.02
293(2)
C11H14INOSe
382.09
297(2)
C12H17IN2Se
395.14
297(2)
Crystal system
Space group
Monoclinic
P21/c
12.0689(14)
18.435(2)
10.1788(12)
90
93.069(2)
90
2261.5(5)
Multi-scan30
3.289
Monoclinic
P2(1)/n
15.7733(13)
9.5329(8)
17.4030(14)
90
110.053(2)
90
2458.2(4)
Multi-scan30
3.026
Orthorhombic
P212121
8.476(2)
8.939(2)
15.576(4)
90
Orthorhombic
Pna21
16.141(2)
12.6448(16)
6.9126(9)
90
Monoclinic
P21/n
8.2818(7)
14.3309(12)
10.7167(9)
90
97.3370(10)
90
1261.50(18)
Multi-scan30
5.399
Monoclinic
P21/c
7.8591(13)
15.772(3)
11.3391(19)
90
96.523(3)
90
1396.4(4)
Multi-scan30
4.878
˚
a/A
˚
b/A
˚
c/A
a/◦
b/◦
c /◦
90
90
90
90
3
˚
V/A
1180.1(6)
Multi-scan30
3.381
0.0227
0.0519
1410.9(3)
Multi-scan30
8.306
0.0685
0.1244
Absorption correction
l(Mo-Ka)/mm−1
R1 [I > 2r(I)]
wR2
0.0497
0.1024
1.126
0.0470
0.1001
1.093
0.0318
0.0652
1.174
0.0566
0.1133
1.264
GOF on F2
1.110
1.173
(decomp.). Anal. Calcd for C12H17IN2Se (395.14): C, 36.48; H,
4.34; N, 7.09; Found: C, 36.23; H, 4.11; N, 6.83%. 1H NMR
(CDCl3, +26 ◦C): d 2.37 (3 H, s, NCH3), 2.50–3.00 (8 H, br,
H-8,9,10,11, N–CH2–CH2–NMe) (at +60 ◦C, this resonance is
resolved into 2 singlets at 2.66 and 2.81 ppm for H-9,10 and H-
8,11, respectively), 3.74 (2 H, s, H-7, C6H4–CH2–N), 7.05 (1 H,
Acknowledgements
Financial support from National University Research Council
(CNCSIS, Romania; Research Project No. TD-96/2004) and
the Ministry of Education and Research of Romania (CERES,
Research Project No. 4-62/2004; Excellency Research Program,
Research Projects No. 18—Contract No. 1536/2006 and No. 2-
CEx-06-11-41/2006) is greatly appreciated. We warmly acknowl-
edge Dr Svetlana Simova for helpful discussions and assistance in
setting up the H,C-undecoupled-HSQC experiments.21 We also
thank the NATIONAL CENTER FOR X-RAY DIFFRAC-
TION and Dr Richard Varga (“Babes-Bolyai” University, Cluj-
Napoca, Romania) for support in the solid state structure deter-
minations.
3
4
dd, H-3, C6H4, JHH 7.2, JHH 0.9 Hz), 7.19 (1 H, td, H-4, C6H4,
3JHH 7.3, 4JHH 1.3 Hz), 7.23 (1 H, td, H-5, C6H4, 3JHH 7.8, 4JHH 1.8
3
4
1
Hz), 8.07 (1 H, dd, H-6, C6H4, JHH 8.0, JHH 1.2 Hz). H NMR
(CDCl3, −40 ◦C): d 2.32 (3 H, s, NCH3), 2.46 (4H, t, H-9,10,
N–CH2–CH2–NMe, 3JHH 7.5 Hz), 2.78 (2 H, d, pro-trans-H-8,11,
2
N–CH2–CH2–NMe, JHH 9.3 Hz), 3.07 (2 H, d, pro-cis-H-8,11,
N–CH2–CH2–NMe, 2JHH 9.1 Hz), 3.74 (2 H, s, H-7, C6H4–CH2–
3
4
N), 7.04 (1 H, dd, H-3, C6H4, JHH 6.4, JHH 1.3 Hz), 7.18 (2 H,
3
4
m, H-4,5 C6H4), 8.01 (1 H, dd, H-6, C6H4, JHH 7.0, JHH 1.8
Hz). 13C NMR (CDCl3, +26 ◦C): d 45.55 (s, NCH3), 53.28 (s,
C-8,11), 53.83 (s, C-9,10), 63.91 (s, C-7), 126.19 (s, C-3), 126,46
(s, C-4), 129.19 (s, C-5), 130.70 (s, C-1), 135.84 (s, C-6), 136.34
(s, C-2).
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The details of the crystal structure determination and refinement
for compounds 1–3, 4·HBr, 5 and 6 are given in Table 4. Data
were collected on Bruker SMART APEX diffractometer, using
˚
graphite-monochromated Mo-Ka radiation (k = 0.71073 A).
For this purpose the crystals were attached with epoxy glue
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(297 K). The structures were refined with anisotropic thermal
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CCDC reference numbers 619306 (1), 608161 (2), 608159 (3),
619305 (4·HBr), 608162 (5) and 608160 (6).
For crystallographic data in CIF or other electronic format see
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This journal is
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Dalton Trans., 2007, 2187–2196 | 2195
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2196 | Dalton Trans., 2007, 2187–2196
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The Royal Society of Chemistry 2007
©