New examples of the unusual X-phenylcyanamido bridging ligands. Crystal structure and magnetic properties of MnII derivatives

Article abstract of DOI:10.1016/j.poly.2004.02.013

Several new Mn^II compounds with X-phenylcyanamido (Xpcyd) and 1,10-phenantroline (phen) ligands of formula [Mn(3-Clpcyd)(H₂O)(phen) ₂](NO₃)·H₂O (1), [{Mn(3-Fpcyd)(MeOH) (phen)}₂(μ-3-Fpcyd)₂] (2), [{Mn(3-Fpcyd)(EtOH)(phen)} ₂(μ-3-Fpcyd)₂] (3), [{Mn(3-Clpcyd)(MeOH)(phen)} ₂(μ-3-Clpcyd)₂] (4) and [{Mn(4-Clpcyd)(EtOH)(phen)} ₂(μ-4-Clpcyd)₂] (5) have been synthesised and characterised. Mononuclear compound 1 crystallises in the monoclinic system, P2₁/c space group, dinuclear compounds 2-5 crystallise in the monoclinic system, C2/c space group 2, triclinic system, P1? space group 3-4 and in the monoclinic system, P2₁/a space group 5. These compounds contain the unusual end-to-end R-cyanamide bridge and give supramolecular one-dimensional networks by means of H-bonds involving the N-amide atoms of the phenylcyanamide ligands. Susceptibility measurements on compounds 2-5 reveal moderate AF coupling in all cases. Coupling constants related to the phenylcyanamido bridges are compared with the superexchange model recently proposed for ligands of this kind.

Full text of DOI:10.1016/j.poly.2004.02.013

Polyhedron 23 (2004) 1409–1417
www.elsevier.com/locate/poly
New examples of the unusual X-phenylcyanamido bridging
ligands. Crystal structure and magnetic properties of MnII derivatives
a,
Albert Escuer , Franz A. Mautner , Nuria Sanz , Ramon Vicente
b
a
a
*
ꢀ
a
Departament de Quꢀımica Inorgꢁanica, Universitat de Barcelona, Martꢀı Franquꢀes 1-11, 08028 Barcelona, Spain
b
Institut f€ur Physikalische und Theoretische Chemie, Technische Universit€at Graz, A-8010 Graz, Austria
Received 9 January 2004; accepted 20 February 2004
Available online 12 April 2004
Abstract
Several new MnII compounds with X-phenylcyanamido (Xpcyd) and 1,10-phenantroline (phen) ligands of formula [Mn(3-
Clpcyd)(H2O)(phen)2](NO3) ꢀ H2O (1), [{Mn(3-Fpcyd)(MeOH)(phen)}2(l-3-Fpcyd)2] (2), [{Mn(3-Fpcyd)(EtOH)(phen)}2(l-3-
Fpcyd)2] (3), [{Mn(3-Clpcyd)(MeOH)(phen)}2(l-3-Clpcyd)2] (4) and [{Mn(4-Clpcyd)(EtOH)(phen)}2(l-4-Clpcyd)2] (5) have been
synthesised and characterised. Mononuclear compound 1 crystallises in the monoclinic system, P21=c space group, dinuclear
ꢂ
compounds 2–5 crystallise in the monoclinic system, C2=c space group 2, triclinic system, P1 space group 3–4 and in the monoclinic
system, P21=a space group 5. These compounds contain the unusual end-to-end R-cyanamide bridge and give supramolecular one-
dimensional networks by means of H-bonds involving the N-amide atoms of the phenylcyanamide ligands. Susceptibility mea-
surements on compounds 2–5 reveal moderate AF coupling in all cases. Coupling constants related to the phenylcyanamido bridges
are compared with the superexchange model recently proposed for ligands of this kind.
Ó 2004 Elsevier Ltd. All rights reserved.
Keywords: Manganese; Pheylcyanamide; Magnetic properties; Crystal structures
1. Introduction
crystallinity of the resulting compounds and in the dif-
ferent coordination properties of the two nitrogen atoms:
one N-nitrile, (which coordinates preferently) and one
N-amide atom, with characteristic bond parameters in
each case. Also remarkable is the strong tendency to
participate in H-bonded extended networks of X-pcyd
ligands by means of the N-amide atom. Exploration of
the coordination properties of these kinds of ligands is
still a challenge, because most of the work performed
with Xpcyd derivatives has been done with RuIII (mainly
mononuclear systems) and only a few dinuclear systems
derived from other cations such as AgI, CuI or CuII have
been reported [3]. The evident relationship with other
pseudohalide ligands which in the last few years have
provided a great variety of structural topologies and
magnetic properties, including ferro, antiferro, (homo-
geneous or alternating) or in some few cases, ferrimag-
netic systems [4–7], encourages us to explore the
magnetic properties of pcyd derivatives.
Phenylcyanamide ligands (Pcyd) are interesting and
practically unexplored ligands from the synthetic and
magnetic point of view. Very recently, we have reported
the first magnetic measurements on systems with
different dimensionality containing the MnII–(NCN)2–
MnII unit [1,2], the cyanamido group (NCN) being co-
ordinated in the end-to-end mode. In these preliminary
works, we demonstrate the ability of this kind of bridge
to transmit moderate antiferromagnetic coupling. We
propose, on the basis of MO calculations, that the l1;3
-
NCN pcyd ligands have an intermediate place between
azido and dicyanamido as superexchange mediators [1].
From the synthetic point of view, pcyd ligands offer a
wide range of possibilities based on the use of different X-
pcyd derivatives which can modify the solubility and
* Corresponding author. Tel.: +934021264; fax: +934907725.
E-mail addresses: albert.escuer@qi.ub.es (A. Escuer), maut-
ner@ptc.tu-graz.ac.at (F.A. Mautner).
Following our work with this family of ligands,
we now report five new MnII/Xpcyd compounds (using
0277-5387/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2004.02.013

1410
A. Escuer et al. / Polyhedron 23 (2004) 1409–1417
3-fluoro, 3-chloro or 4-chlorophenylcyanamide, 3-Fpcyd,
3-Clpcyd or 4-Cl-pcyd, respectively) in combination with
the blocking 1,10-phenantroline ligand (phen). The new
systems, one mononuclear and four dinuclear molecular
derivatives, shows newly how the H-bonds play a central
role in generating one-dimensional supramolecular ar-
rangements. Measurement of their magnetic properties
adds new data to check the recently proposed coupling
model [1].
phurization of the corresponding X-phenylthiourea with
lead acetate, following the general synthetic procedure
described for the haloderivatives of phenylcyanamide [8].
The five compounds were prepared following a
common procedure: reaction of a solution of manganese
nitrate hexahydrate (1 mmol) and phenantroline (2
mmol for 1 and 1 mmol for 2–5) in 50 mL of methanol
(for 1, 2 or 4) or ethanol (for 3 and 5) with a solution of
the corresponding XpcydH (2 mmol) in 6 mL of NaOH
0.2 M to deprotonate the ligand, produce yellowish so-
lutions. After filtration of possible impurities, the re-
sulting clear solutions were allowed to evaporate, giving
yellowish-orange crystalline compounds suitable for X-
ray measurements in one week. Yield for the five com-
pounds around 40%. Elemental Anal. Calc. for 1 as
C31H24ClMnN7O5 (665): C, 56.0; H, 3.6; N, 14.7.
Found: C, 55.9; H, 3.4; N, 14.7%. Elemental Anal. Calc.
for 2 as C54H40F4Mn2N12O2 (1074.9): C, 60.3; H, 3.7;
N, 15.6. Found: C, 59.9; H, 3.7; N 15.9%. Elemental
Anal. Calc. for 3 as C56H44F4Mn2N12O2 (1102.9): C,
61.0; H, 4.0; N, 15.2. Found: C, 61.3; H, 4.0; N, 15.3%.
Elemental Anal. Calc. for 4 as C54H40Cl4Mn2N12O2
(1140.7): C, 56.9; H, 3.5; N, 14.7. Found: C, 56.0; H, 3.5;
N, 15.0%. Elemental Anal. Calc. for 5 as solvent free 5b
C52H32Cl4Mn2N12 (1076.6): C, 58.0; H, 3.0; N, 15.6.
Found: C, 58.3; H, 3.2; N, 15.6%.
2. Experimental
2.1. Physical measurements
Magnetic susceptibility measurements were carried out
on polycrystalline samples with a DSM8 pendulum sus-
ceptometer working in the range 4–300 K, under magnetic
fields of approximately 1 T or in a SQUID instrument in
the range 2–300 K under an external field of 0.1 T at the
Magnetochemistry Service of the University of Barce-
lona. Diamagnetic corrections were estimated from Pas-
cal Tables. The infrared spectra (4000–400 cmꢁ1) were
recorded from KBr pellets on a Nicolet 520 FTIR spec-
trophotometer. EPR spectra were recorded with a Bruker
ES200 spectrometer at X-band frequency. Thermogravi-
metric measurements were carried out in a Mettler TG 50
instrument at a heating rate of 10 °C minꢁ1
.
2.3. X-ray data collection for 1–5
2.2. Synthesis
The X-ray single-crystal data for [Mn(3-Clpcyd)
(H2O)(phen)2] (NO3) ꢀ H2O (1), [{Mn(3-Fpcyd)(MeOH)
(phen)}2(l-3-Fpcyd)2] (2), [{Mn(3-Fpcyd)(EtOH)(phen)}2
Neutral 3-fluoro-, 3-chloro and 4-chlorophenylcya-
namide (XpcydH) were prepared in all cases by desul-
Table 1
Crystal data and structure refinement for 1–5
(1)
(2)
(3)
(4)
(5)
Formula
Formula weight
C
31H24ClMnN7O5
C54H40F4Mn2N12O2
1074.86
C2=c
15.994(7)
13.853(5)
22.268(7)
90
C56H44F4Mn2N12O2
1102.91
C54H40Cl4Mn2N12O2
1140.66
C56H44Cl4Mn2N12O2
1168.71
P21=a
10.588(4)
22.866(8)
11.338(4)
90
664.96
P21=c
12.798(3)
11.944(3)
20.039(5)
90
ꢂ
ꢂ
Space group
ꢃ
P1
P1
a (A)
9.921(3)
10.660(3)
11.750(3)
99.57(2)
94.05(2)
90.25(2)
1222.1(6)
1
10.175(3)
11.549(4)
11.772(4)
77.33(2)
73.23(2)
76.37(2)
1270.1(7)
1
ꢃ
b (A)
ꢃ
c (A)
a (°)
b (°)
c (°)
104.58(2)
90
94.78(3)
90
102.28(3)
90
3
ꢃ
V (A )
2964(1)
4
4917(3)
4
87(2)
2682(2)
2
87(2)
Z
T (K)
k (Mo Ka) (A)
qcalc (g cmꢁ3
298(2)
0.71069
1.490
0.590
4718
87(2)
87(2)
ꢃ
0.71069
1.452
0.585
0.71069
1.499
0.591
0.71069
1.491
0.764
0.71069
1.447
0.725
)
l (Mo Ka) (mmꢁ1
Collected data
Independent data
Rint
)
5616
4824
6184
5386
6413
5589
5753
4720
3882
0.0183
432
0.0352
0.0323
339
0.0376
358
0.0320
339
0.0507
348
Refined parameters
Ra ½I > 2sðIÞꢂ
0.0657
0.1901
0.0456
0.1043
0.0500
0.1236
0.0605
0.1614
xR2b
0.0793
P
P
a RðFoÞ ¼ kFoj ꢁ jFck= jFoj.
P
P
2
2
2
2
4
1=2
b xRðFoÞ ¼ f ½xððFoÞ ꢁ ðFcÞ Þ ꢂ= ½xðFoÞ ꢂg
.

A. Escuer et al. / Polyhedron 23 (2004) 1409–1417
1411
(l-3-Fpcyd)2] (3), [{Mn(3-Clpcyd)(MeOH)(phen)}2(l-3-
Clpcyd)2] (4) and [{Mn(4-Clpcyd)(EtOH)(phen)}2(l-4-
Clpcyd)2] (5) were collected on a modified STOE
four-circle diffractometer. The crystallographic data,
conditions retained for the intensity data collection, and
some features of the structure refinement are listed in
Table 1. Graphite-monochromatized MoKa radiation
polarisation effects and intensity decay. The structures
were solved by direct methods using the SHELX-86 com-
puter program [9], and refined by full-matrix least-squares
methods on F2, using the SHELXS-93 program [10] in-
corporated in the SHELXTL/PC package [11] and PLUTON-
92 [12] program. All non-hydrogen atoms were refined
anisotropically. Hydrogen atoms bonded to C-atoms were
located on calculated positions by use of the HFIX utility
of the SHELXS-93 program whereas the remaining hy-
drogen atoms were located from difference Fourier maps
and included in the final refinement cycles by use of O–H
distance restraints. For compounds 1 and 3 the occupancy
of disordered atoms Cl(1)/Cl(2) and F(2)/F(12) was re-
fined as 0.564(2)/0.436(2) and 0.827(5)/0.173(5), respec-
tively. IR Xpcyd main absorptions: 2136 cmꢁ1 1, 2170,
2143 cmꢁ1 2 and 3, 2170, 2140 cmꢁ1 4 and 2149 cmꢁ1 5b.
ꢃ
(k ¼ 0:71069 A) with the x-scan technique was used to
collect the data sets. Corrections were applied for Lorentz-
3. Results and discussion
3.1. Description of the structures
3.1.1. Crystal structure of [Mn(3-Clpcyd)(H2O)-
(phen)2](NO3) ꢀ H2O (1)
The structure consists of mononuclear [Mn(3-
Clpcyd)(H2O)(phen)2]þ units and nitrate counterions.
Hexacoordination of the MnII atoms is completed by
two phenantroline ligands and one N-nitrile atom from
the 3-Clpcydꢁ ligand and one water molecule, Fig. 1.
Selected bond parameters are listed in Table 2.
Fig. 1. ORTEP labelled plot (probability 30%) for compound 1. For
the sake of clarity, only the labels for the coordination sphere of the
MnII cations and the NCN groups are shown. Cl(1)/Cl(2) atoms cor-
respond to the disordered Cl atom of the 3-Clpcyd ligand.
Table 2
ꢃ
Selected bond lengths (A) and angles (°) for 1
Manganese environment
Bond lengths
Mn(1)–O(1)
Mn(1)–N(4)
Mn(1)–N(5)
2.149(3)
2.300(2)
2.305(2)
Mn(1)–N(1)
Mn(1)–N(6)
Mn(1)–N(7)
2.119(3)
2.319(3)
2.301(3)
Bond angles
O(1)–Mn(1)–N(6)
O(1)–Mn(1)–N(1)
O(1)–Mn(1)–N(7)
O(1)–Mn(1)–N(4)
O(1)–Mn(1)–N(5)
N(1)–Mn(1)–N(7)
N(1)–Mn(1)–N(4)
N(1)–Mn(1)–N(5)
164.5(1)
N(6)–Mn(1)–N(1)
N(6)–Mn(1)–N(7)
N(6)–Mn(1)–N(4)
N(6)–Mn(1)–N(5)
N(7)–Mn(1)–O(4)
N(7)–Mn(1)–N(5)
N(4)–Mn(1)–N(5)
97.5(1)
72.1(1)
84.0(1)
93.4(1)
91.3(1)
159.5(1)
72.3(1)
92.2(1)
94.1(1)
89.6(1)
98.0(1)
102.6(1)
165.8(1)
93.5(1)
3-Clpcyd ligand
Bond lengths
N(1)–C(31)
1.165(4)
1.399(5)
C(31)–N(2)
1.287(5)
174.4(3)
N(2)–C(32)
Bond angles
Mn(1)–N(1)–C(31)
C(31)–N(2)–C(32)
168.3(2)
120.1(3)
N(1)–C(31)–N(2)
H-bonds
O–H
Hꢀ ꢀ ꢀO
1.96(3)
1.83(3)
2.03(3)
2.16(5)
Oꢀ ꢀ ꢀO/N
2.779(4)
2.664(4)
2.826(4)
2.960(4)
Angle
178(2)
179(4)
167(5)
165(5)
O(1)–H(31)–O(4)
O(1)–H(32)–O(2)
O(2)–H(33)–N(2)
O(2)–H(34)–O(4)
0.82(3)
0.81(3)
0.81(3)
0.82(5)

1412
A. Escuer et al. / Polyhedron 23 (2004) 1409–1417
The coordination polyhedron is strongly distorted as
In a similar fashion to previously reported dinuclear
systems with similar arrangement [1,2], the R–OH co-
ordinated solvent forms H-bonds with the N-amide
atom of the neighbouring terminal X-pcyd ligand, giving
double H-bond bridges and a one-dimensional ar-
rangement of the dinuclear units, in which the intra-
result of placement of the phen ligands, which impose two
N–Mn–N bond angles around 72°, and consequently
several bond angles are strongly deviated from the regular
90° value. Bond distances are also asymmetric, with two
short distances Mn(1)–O(1) and Mn(1)–N(1) of 2.149(3)
ꢃ
ꢃ
and 2.119(3) A, respectively, whereas the four Mn–
molecular Mnꢀ ꢀ ꢀMn distance is always 1–2 A shorter
ꢃ
N(phen) bond distances are larger than 2.300 A. Coor-
dination of the 3-Clpcyd ligand is close to linearity with a
Mn(1)–N(1)–C(31) bond angle of 168.3(2)°.
Mononuclear units form a supramolecular structure
by means of H-bonds involving the N-amide (3-Clpcyd),
the coordinated water molecule, the nitrate counterion
and the crystallization water molecule, giving a one-di-
mensional double chain arrangement along b crystallo-
graphic axis, Fig. 2. Shorter Mnꢀ ꢀ ꢀMn distance is
than the intermolecular Mnꢀ ꢀ ꢀMn. As example, Fig. 3
show one of these H-bond one-dimensional arrays.
Description of relevant details of the bond parameters
of the bridging ligands will be set out separately below.
3.1.3. Crystal structure of [{Mn(3-Fpcyd)(MeOH)
(phen)}2(l-3-Fpcyd)2] (2)
Selected bond parameters are given in Table 3 and a
labelled ORTEP plot of the dinuclear unit is shown in
Fig. 4.
ꢃ
8.465(1) A.
Bond angles in the bridging region follow the general
trends of this kind of bridges, that is to say, a large
Mn(1A)–N(1)–C(1) (nitrile) bond angle of 157.7(3)° and a
closed Mn(1)–N(2)–C(1) (amide) bond angle of 114.4(2)°.
Mn–(NCN)2–Mn ring shows a chair distortion which
may be evaluated from the dihedral angle (named d) be-
tween the (NCN)2 plane and the N(1)–Mn(1)–N(2A)
plane as 12.6(1)°. The bridging 3-Fpcyd ligand is practi-
cally coplanar with the main (NCN)2 plane, the angle
between the direction C(2)–N(2) and this plane being only
3.1.2. Common remarks on crystal structure of the
dinuclear compounds 2–5
The four structures show common features that permit
a general description. In all cases the system consists of
dinuclear centrosymmetric entities, with double Xpcyd
bridge. In addition to the N-amide and N-nitrile atoms
from the bridging ligands, coordination polyhedron
around MnII atoms is completed with one bidentate
phenantroline ligand, one terminal Xpcyd ligand and one
solvent (MeOH or EtOH) molecule in trans position with
respect to the N-amide atom of the bridging Xpcyd.
Also, for all of them, coordination polyhedra are
strongly distorted as a consequence of the coordination
of phen ligands that gives N–Mn–N bond angles close to
72°. Bond distances in the bridging region show as
common features large Mn–N(amide) bond distances,
ꢃ
4.8(2)°. Intramolecular Mnꢀ ꢀ ꢀMn distance is 5.498(1) A
whereas the intermolecular Mnꢀ ꢀ ꢀMn distance trough the
ꢃ
H-bonds direction is 6.690 A.
3.1.4. Crystal structure of [{Mn(3-Fpcyd)(EtOH)
(phen)}2(l-3-Fpcyd)2] (3)
ꢃ
Selected bond parameters are given in Table 4 and a
labelled ORTEP plot of the dinuclear unit is shown in
Fig. 5.
greater than 2.300 A, short Mn–N-nitrile bond distances
ꢃ
around 2.150 A and intermediate Mn–O(solvent) bond
ꢃ
distances around 2.200 A.
This compound is analogous to 2 with EtOH instead
the coordinated MeOH. Therefore, this minor variation
in the coordinated solvent introduce important differ-
Fig. 2. One-dimensional H-bond network for compound 1. H-bonds
(dashed lines) involve the N-amide atoms of terminal 3-Clpcyd ligands,
the coordinated water molecule, the O(4) atom from nitrate anion and
the crystallization water molecule present in the structure. The two
positions for the disordered Cl atom of the 3-Clpcyd ligand are shown
in the plot.
Fig. 3. H-bonds involving the N-amide and the –OH group of the
coordinated solvent that allow to one-dimensional extended arrays for
2–5. As example, in the figure is shown compound 4.

A. Escuer et al. / Polyhedron 23 (2004) 1409–1417
1413
Table 3
ꢃ
Selected bond lengths (A) and angles (°) for compound 2
Manganese environment
Bond lengths
Mn(1)–O(1)
Mn(1)–N(2)
Mn(1)–N(1A)
2.228(3)
2.293(3)
2.165(2)
Mn(1)–N(3)
Mn(1)–N(5)
Mn(1)–N(6)
2.129(3)
2.284(3)
2.303(3)
Bond angles
O(1)–Mn(1)–N(2)
O(1)–Mn(1)–N(1A)
O(1)–Mn(1)–N(3)
O(1)–Mn(1)–N(6)
O(1)–Mn(1)–N(5)
N(1A)–Mn(1)–N(3)
N(1A)–Mn(1)–N(6)
N(1A)–Mn(1)–N(5)
177.5(1)
89.4(1)
88.4(1)
77.4(1)
87.1(1)
103.0(1)
160.6(1)
91.8(1)
N(2)–Mn(1)–N(1A)
N(2)–Mn(1)–N(3)
N(2)–Mn(1)–N(6)
N(2)–Mn(1)–N(5)
N(3)–Mn(1)–N(6)
N(3)–Mn(1)–N(5)
N(6)–Mn(1)–N(5)
88.5(1)
91.1(1)
105.0(1)
94.0(1)
92.3(1)
164.5(1)
72.2(1)
3-Fpcyd ligands
Bond lengths
N(1)–C(1)
1.162(5)
1.295(5)
1.411(5)
N(3)–C(9)
C(9)–N(4)
N(4)–C(10)
1.167(5)
1.286(5)
1.402(5)
C(1)–N(2)
N(2)–C(2)
Bond angles
Mn(1A)–N(1)–C(1)
N(1)–C(1)–N(2)
C(1)–N(2)–Mn(1)
Mn(1)–N(2)–C(2)
C(1)–N(2)–C(2)
157.7(3)
176.0(4)
114.2(2)
128.5(2)
117.2(3)
Mn(1)–N(3)–C(9)
N(3)–C(9)–N(4)
C(9)–N(4)–C(10)
157.2(3)
178.1(5)
116.2(3)
H-bonds
O–H
0.80(3)
Hꢀ ꢀ ꢀN
Oꢀ ꢀ ꢀN
Angle
163(5)
O(1)–H(1)–N(4)
1.99(3)
2.773(4)
110.6(2)°. Mn–(NCN)2–Mn ring show a greater chair
distortion, being the dihedral angle d between the (NCN)2
plane and the N(1A)–Mn(1)–N(2) plane 37.6(1)°.
In this case, the 3-Fpcyd ligand is not coplanar with the
main (NCN)2 plane, being the angle of the C(2)–N(2)
vector with this plane of 22.9(1)°. Intramolecular
ꢃ
Mnꢀ ꢀ ꢀMn distance is 5.233(1) A and the intermolecular
Mnꢀ ꢀ ꢀMn distance trough the H-bonds direction is
ꢃ
7.115(1) A.
3.1.5. Crystal structure of [{Mn(3-Clpcyd)(MeOH)
(phen)}2(l-3-Clpcyd)2] (4)
Selected bond parameters are given in Table 5 and a
labelled ORTEP plot of the dinuclear unit is shown in
Fig. 6.
Mn(1)–N(1A)–C(1A) (nitrile) bond angle is only of
154.0(2)° and Mn(1)–N(2)–C(1) (amide) bond angle is
111.7(2)°. Mn–(NCN)2–Mn ring shows an intermediate
chair distortion, being the dihedral angle d between the
(NCN)2 plane and the N(1A)–Mn(1)–N(2) plane17.2(1)°.
In this case, the 3-Clpcyd ligands are strongly devi-
ated from planarity with the main (NCN)2 plane, the
angle of the C(2)–N(2) vector with this plane being
Fig. 4. ORTEP labelled plot (probability 30%) for compound 2.
ꢃ
ences in the bond parameters of the compound. Mn(1)–
N(1A)–C(1A) (nitrile) bond angle is only of 140.8(2)° and
also Mn(1)–N(2)–C(1) (amide) bond angle reduces to
34.5(1)°. Intramolecular Mnꢀ ꢀ ꢀMn distance is 5.430(1) A
and the intermolecular Mnꢀ ꢀ ꢀMn distance trough the H-
ꢃ
bonds direction is 6.517(1) A.

1414
A. Escuer et al. / Polyhedron 23 (2004) 1409–1417
Table 4
ꢃ
Selected bond lengths (A) and angles (°) for compound 3
Manganese environment
Bond lengths
Mn(1)–O(1)
Mn(1)–N(2)
Mn(1)–N(1A)
2.250(2)
2.291(2)
2.158(2)
Mn(1)–N(3)
Mn(1)–N(5)
Mn(1)–N(6)
2.128(2)
2.259(2)
2.318(2)
Bond angles
O(1)–Mn(1)–N(2)
O(1)–Mn(1)–N(1A)
O(1)–Mn(1)–N(3)
O(1)–Mn(1)–N(6)
O(1)–Mn(1)–N(5)
N(1A)–Mn(1)–N(3)
N(1A)–Mn(1)–N(6)
N(1A)–Mn(1)–N(5)
170.6(1)
90.8(1)
91.9(1)
84.5(1)
84.4(1)
100.6(1)
92.9(1)
165.0(1)
N(2)–Mn(1)–N(1A)
N(2)–Mn(1)–N(3)
N(2)–Mn(1)–N(6)
N(2)–Mn(1)–N(5)
N(3)–Mn(1)–N(6)
N(3)–Mn(1)–N(5)
N(6)–Mn(1)–N(5)
90.1(1)
97.1(1)
86.1(1)
92.3(1)
166.1(1)
93.8(1)
72.5(1)
3-Fpcyd ligands
Bond lengths
N(1)–C(1)
1.172(3)
1.292(3)
1.406(3)
N(3)–C(10)
C(10)–N(4)
N(4)–C(11)
1.167(3)
1.286(3)
1.398(3)
C(1)–N(2)
N(2)–C(2)
Bond angles
Mn(1A)–N(1)–C(1)
N(1)–C(1)–N(2)
C(1)–N(2)–Mn(1)
Mn(1)–N(2)–C(2)
C(1)–N(2)–C(2)
140.8(2)
173.9(3)
110.6(2)
132.4(2)
117.1(2)
Mn(1)–N(3)–C(10)
N(3)–C(10)–N(4)
C(10)–N(4)–C(11)
163.6(2)
174.6(3)
119.8(2)
H-bonds
O–H
0.87(3)
Hꢀ ꢀ ꢀN
Oꢀ ꢀ ꢀN
Angle
174(4)
O(1)–H(1)–N(4)
1.84(3)
2.701(3)
3.1.6. Crystal structure of [{Mn(4-Clpcyd)(EtOH)
(phen)}2(l-4-Clpcyd)2] (5)
Selected bond parameters are given in Table 6 and a
labelled ORTEP plot of the dinuclear unit is shown in
Fig. 7.
Mn(1A)–N(1)–C(1) (nitrile) bond angle is only of
148.4(4)° and Mn(1)–N(2)–C(1) (amide) bond angle is
110.5(3)°. Mn–(NCN)2–Mn ring shows a strong chair
distortion, the dihedral angle d between the (NCN)2
plane and the N(1A)–Mn(1)–N(2) plane being 26.6(1)°.
The 4-Clpcyd ligands are close to co-planarity with the
main (NCN)2 plane, the angle of the C(2)–N(2) vector
with this plane being 5.8(3)°. Intramolecular Mnꢀ ꢀ ꢀMn
ꢃ
distance is 5.319(1) A and the intermolecular Mnꢀ ꢀ ꢀMn
ꢃ
distance trough the H-bonds direction is 6.258(1) A.
3.2. Thermal behaviour
Crystals of dinuclear compounds 2–5 degraded more
or less slowly if they are maintained in open air, due to the
loss of coordinated solvent. Structural determination was
performed at low temperature on crystals just extracted
from the mother solutions. In order to characterise the
reason for this behaviour, thermogravimetric measure-
ments on fresh crystals or freshly powdered crystalline
samples.
Fig. 5. ORTEP labelled plot (probability 30%) for compound 3. The
two positions for the disordered F atom of the 3-Fpcyd ligand are
shown in the plot.
For compounds 2–4 the measurements reveal a rea-
sonable stability, with loss of coordinated solvent at

A. Escuer et al. / Polyhedron 23 (2004) 1409–1417
1415
Table 5
ꢃ
Selected bond lengths (A) and angles (°) for compound 4
Manganese environment
Bond lengths
Mn(1)–O(1)
Mn(1)–N(2)
Mn(1)–N(1A)
2.216(2)
2.310(2)
2.154(2)
Mn(1)–N(3)
Mn(1)–N(5)
Mn(1)–N(6)
2.124(3)
2.309(2)
2.286(3)
Bond angles
O(1)–Mn(1)–N(2)
O(1)–Mn(1)–N(1A)
O(1)–Mn(1)–N(3)
O(1)–Mn(1)–N(6)
O(1)–Mn(1)–N(5)
N(1A)–Mn(1)–N(3)
N(1A)–Mn(1)–N(6)
N(1A)–Mn(1)–N(5)
177.2(1)
87.1(1)
91.3(1)
81.8(1)
84.9(1)
102.3(1)
161.4(1)
91.4(1)
N(2)–Mn(1)–N(1A)
N(2)–Mn(1)–N(3)
N(2)–Mn(1)–N(6)
N(2)–Mn(1)–N(5)
N(3)–Mn(1)–N(6)
N(3)–Mn(1)–N(5)
N(6)–Mn(1)–N(5)
89.8(1)
90.0(1)
100.6(1)
94.4(1)
93.1(1)
165.7(1)
72.7(1)
3-Clpcyd ligands
Bond lengths
N(1)–C(1)
1.167(3)
1.295(3)
1.416(3)
N(3)–C(9)
C(9)–N(4)
N(4)–C(10)
1.161(3)
1.289(3)
1.401(4)
C(1)–N(2)
N(2)–C(2)
Bond angles
Mn(1A)–N(1)–C(1)
N(1)–C(1)–N(2)
C(1)–N(2)–Mn(1)
Mn(1)–N(2)–C(2)
C(1)–N(2)–C(2)
154.0(2)
175.6(3)
111.7(2)
124.1(2)
116.7(2)
Mn(1)–N(3)–C(9)
N(3)–C(9)–N(4)
C(9)–N(4)–C(10)
164.4(3)
173.3(3)
119.7(2)
H-bonds
O–H
0.87(3)
Hꢀ ꢀ ꢀN
Oꢀ ꢀ ꢀN
Angle
170(3)
O(1)–H(1)–N(4)
1.83(3)
2.685(4)
5.95%) and 6.6% for 3 (theoretical 8.3%) and 5.6% for 4
(theoretical 5.62%). In contrast, compound 5 does not
show relevant loss of weight until 250 °C, corresponding
to the decomposition of the complex. For 5, the loss of
coordinated ethanol is very fast and becomes practically
total in the time of preparation of the sample under a dry
nitrogen atmosphere. On the basis of these data, com-
pounds 2–4 can be studied magnetically as the dinuclear
entities structurally characterized. But compound 5
should be assumed to be a homogeneous chain with
double 4-Clpcyd bridge with formula [Mn(phen)(l-4-
Clpcyd)2]n (5b). This assumption is reasonable on the
basis of the arrangement of the H-bonds and the vicinity
of the N-amide atoms of the terminal 4-Clpcyd ligands to
the corresponding MnII atom of the neighbour dinuclear
molecule and agree with the analytical data and the
single IR absorption in the nitrile region at 2149 cmꢁ1
.
As corroborated by the EPR and susceptibility mea-
surements, as is shown in the next section, [Mn(phen)(l-
4-Clpcyd)2]n (5b) formulation should be assumed for the
solvent-free powdered compound.
Fig. 6. ORTEP labelled plot (probability 30%) for compound 4.
3.3. Susceptibility measurements and powder EPR
spectrum
similar temperatures (120, 130, and 135 °C). The three
compounds start to decompose at temperatures greater
than 250 °C. The loss of weight agrees with the alcohol
molecules present in the structure, 5.6% for 2 (theoretical
Susceptibility measurements performed on freshly
powdered samples for the four 2–5 compounds reveals

1416
A. Escuer et al. / Polyhedron 23 (2004) 1409–1417
Table 6
ꢃ
Selected bond lengths (A) and angles (°) for compound 5
Manganese environment
Bond lengths
Mn(1)–O(1)
Mn(1)–N(2)
Mn(1)–N(1A)
2.238(3)
2.312(4)
2.146(4)
Mn(1)–N(3)
Mn(1)–N(5)
Mn(1)–N(6)
2.112(5)
2.334(5)
2.268(4)
Bond angles
O(1)–Mn(1)–N(2)
O(1)–Mn(1)–N(3)
O(1)–Mn(1)–N(1A)
O(1)–Mn(1)–N(5)
O(1)–Mn(1)–N(6)
N(3)–Mn(1)–N(1A)
N(3)–Mn(1)–N(5)
N(3)–Mn(1)–N(6)
171.7(1)
93.3(2)
88.6(2)
85.7(1)
82.1(1)
101.4(1)
165.7(1)
93.2(1)
N(2)–Mn(1)–N(3)
N(2)–Mn(1)–N(1A)
N(2)–Mn(1)–N(5)
N(2)–Mn(1)–N(6)
N(1A)–Mn(1)–N(5)
N(1A)–Mn(1)–N(6)
N(5)–Mn(1)–N(6)
92.8(2)
91.4(2)
86.0(2)
95.9(2)
92.9(2)
163.4(2)
72.8(2)
4-Clpcyd ligands
Bond lengths
N(1)–C(1)
1.172(6)
1.294(6)
1.408(6)
N(3)–C(8)
C(8)–N(4)
N(4)–C(9)
1.179(6)
1.295(6)
1.390(6)
C(1)–N(2)
N(2)–C(2)
Bond angles
Mn(1A)–N(1)–C(1)
N(1)–C(1)–N(2)
C(1)–N(2)–Mn(1)
Mn(1)–N(2)–C(2)
C(1)–N(2)–C(2)
148.4(4)
175.7(5)
110.5(3)
130.3(3)
118.0(4)
Mn(1)–N(3)–C(8)
N(3)–C(8)–N(4)
C(8)–N(4)–C(9)
171.9(4)
172.9(5)
120.1(4)
H-bonds
O–H
0.88(5)
Hꢀ ꢀ ꢀN
Oꢀ ꢀ ꢀN
Angle
167(5)
O(1)–H(1)–N(4)
1.87(5)
2.728(5)
more or less weak antiferromagnetic coupling. In all
cases, the vMT value at room temperature is slightly lower
than the 4.375 cm3 K molꢁ1 value by MnII atom, corre-
sponding to the isolated isotropic MnII ions. On cooling,
vMT decreases, tending to zero at low temperature. vMT
versus T plots, Fig. 8, show susceptibility maxima at 11 K
(2), 15.2 K (4) and 15 K for 5b. In contrast, compound 3
does not reach maximum in the susceptibility plot, indi-
cating a much less weak AF coupling. As explained
above, due to the fast loss of coordinated solvent for 5,
this compound was assumed as the homogeneous
[Mn(phen)(l-4-Clpcyd)2]n one-dimensional 5b system
and compounds 2–4 as dinuclear entities. Then, the sus-
ceptibility data were fitted to the expression derived from
the Hamiltonian H ¼ ꢁJS1S2 for an isotropic S ¼ 5=2
dinuclear system and in the case of compound 5 with the
expression derived from H ¼ R ꢁ JSiSiþ1 for an isotropic
S ¼ 5=2 uniform one-dimensional chain [13]. The best fit
parameters obtained for the reported compounds were
remains constant. Peak-to-peak linewidth for the dinu-
clear systems 2–4 are 282, 303 and 255 G. In contrast,
compound 5 exhibits a sharp isotropic signal centred at
g ¼ 2:00 with a linewidth of only 66 G in good agree-
ment with similar one-dimensional pseudohalide or
X-pcyd systems [1,14], giving a complementary confir-
mation of the [Mn(phen)(l-4-Clpcyd)2]n (5b) formula
for the powdered 5 compound.
X-Pcyd ligands introduce a large number of variable
parameters in the coordination sphere of the metallic ion
and in the bridging region. Structural parameters for
compound 5 cannot be used for the solvent-free 5b; thus,
useful magneto-structural data is only available for 2–4.
Previous MO calculations show that the factors favour-
ing the greatest AF coupling are mainly related to the
distortions in the Mn–(NCN)2–Mn region: greater AF
coupling is expected for systems in which the bridging
region is not chair-distorted or in which the NCN-pcyd
mean plane lies coplanar to the (NCN)2 plane [1]. As a
minor effect, for similar distortions, the ligands with the
X-atom in para position (4-Xpcyd) should be more AF
than pcyd or 3-Xpcyd ligands. In our case, compounds
2–4, with 3-Xpcyd (X ¼ F, Cl) and the same phen ter-
minal ligand permit a good comparison of the general
rules for these kinds of compounds. Compound 2 shows
the minor distortion in all parameters, with a d chair
distortion of only 12.6° and shows the 3-Fpcyd ligands
J ¼ ꢁ3:34 cmꢁ1, g ¼ 2:01 for 2, J ¼ ꢁ0:41 cmꢁ1
,
g ¼ 2:01 for 3, )2.89 cmꢁ1 g ¼ 2:01 for 4 and )2.60 cmꢁ1
g ¼ 2:00 for the one-dimensional system 5.
Powder EPR spectra also confirm the dimensionality
of the above compounds. In all cases, the spectra at
room temperature consist of an isotropic absorption
centred at g ¼ 2:00; on cooling, weak half field signals
may be observed, but the main g ¼ 2:00 absorption

A. Escuer et al. / Polyhedron 23 (2004) 1409–1417
1417
closer to 2 and greater out-of-plane deviation of the
phenyl rings, shows a J value closer to 2.
Therefore, it should be taken into account that cor-
relations for ligands of this kind are multiparameter and
only the extreme data, between comparable compounds,
is reliable.
4. Supplementary material
Crystallographic data in CIF format have been de-
posited at the Cambridge Crystallographic data centre
with CCDC reference numbers CCDC 216085–216089
for 1–5, respectively. Copies of this information may be
obtained free of charge from the Director, CCDC, 12
Union Road, Cambridge CB2 1EZ, UK (fax: +44-1223-
336033; E-mail: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk).
Acknowledgements
A.E., R.V., and N.S. thank the Ministerio de Ciencia
ꢀ
y Tecnologıa (Spain), Project BQU2003/0538, for fi-
nancial support of this research. F. M. thanks Prof.
Belaj and Prof. Kratky (University of Graz) for the use
of experimental equipment and OENB (Project 7967)
for financial support.
Fig. 7. ORTEP labelled plot (probability 30%) for compound 5.
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