Phenylcyanamido Ligand Building Molecular, 1-D, and 2-D Systems - Syntheses, Crystal Structures and Magnetic Properties

Article abstract of DOI:10.1002/ejic.200300305

Several Mn^II compounds have been synthesised with the phenylcyanamido ligand, C₆H₅-NCN^-, and characterised by means of single crystal X-ray structure determination. The reported compounds show a wide variety of nuclearity: mononuclear, dinuclear, 1-D, and 2-D compounds are present in which the phenylcyanamido anion (pcyd ^-) acts as a bridging ligand. The mononuclear compound [Mn(pcyd) ₂(phen)₂] (1) crystallises in the orthorhombic system, Pbcn space group; dinuclear compound [{Mn(pcyd)(phen)(MeOH)}₂(μ _1,3-pcyd)₂] (2) crystallises in the monoclinic system, C2/c space group; 1-D chain [Mn(4-bzpy)₂(μ_1,3pcyd) ₂]_n·MeOH (3·MeOH) crystallises in the triclinic system, Pi space group; 2-D network [Mn(μ_1,3-pcyd) ₂(μ-4,4′bpy)]_n·MeOH (4·MeOH) crystallises in the monoclinic system, C2 space group. Susceptibility measurements on compounds 2-4 reveal moderate AF coupling in all cases. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.

Full text of DOI:10.1002/ejic.200300305

FULL PAPER
Phenylcyanamido Ligand Building Molecular, 1-D, and 2-D Systems ؊
Syntheses, Crystal Structures and Magnetic Properties
[a]
[a]
[b]
[a]
´
Albert Escuer, Nuria Sanz, Franz A. Mautner, and Ramon Vicente*
Keywords: Manganese / Magnetic properties / Phenylcyanamido ligands / Bridging ligands
Several MnII compounds have been synthesised with the
phenylcyanamido ligand, C6H5−NCN−, and characterised by
means of single crystal X-ray structure determination. The
reported compounds show a wide variety of nuclearity:
mononuclear, dinuclear, 1-D, and 2-D compounds are pre-
(MeOH)}2(µ1,3-pcyd)2] (2) crystallises in the monoclinic sys-
tem, C2/c space group; 1-D chain [Mn(4-bzpy)2(µ1,3
-
pcyd)2]n·MeOH (3·MeOH) crystallises in the triclinic system,
¯
P1 space group; 2-D network [Mn(µ1,3-pcyd)2(µ-4,4Ј-
bpy)]n·MeOH (4·MeOH) crystallises in the monoclinic sys-
sent in which the phenylcyanamido anion (pcyd−) acts as a tem, C2 space group. Susceptibility measurements on com-
bridging ligand. The mononuclear compound [Mn(pcyd)2-
(phen)2] (1) crystallises in the orthorhombic system, Pbcn
space group; dinuclear compound [{Mn(pcyd)(phen)-
pounds 2−4 reveal moderate AF coupling in all cases.
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2004)
Introduction
With the aim of exploring the magnetic and synthetic
possibilities of the R-phenylcyanamido ligands, we have re-
cently published[5] the syntheses and structural characteris-
ation of several representative MnII derivatives: the mono-
nuclear compound [Mn(3-Clpcyd)2(H2O)2(4-bzpy)2]; the di-
In the last few years, a wide variety of bridging ligands
have been used to promote the magnetic interaction be-
tween transition metal ions in polynuclear systems. In this
sense, the anions azido[1] and dicyanamido[2] have generated
a plethora of new polynuclear compounds ranging from di-
nuclear to 3D with different architectures. The study of the
magnetic behaviour of these compounds has made for fast
growth in the field molecular magnetism. However, the X-
phenylcyanamido ligands (X-pcydϪ), Scheme 1, have prac-
tically been forgotten[3,4] as superexchange mediators in
spite of the similarities with the azido or dicyanamido li-
gands. The XPhϪNCNϪ group is electronically similar to
the azido ligand (N3Ϫ), and it is reasonable to expect similar
coordination modes. On the other hand, the nitrile group
approaches the coordination properties of those observed
for the dicyanamido ligand (mainly for MϪNϪC and
MϪN bond parameters).[2,5]
nuclear
ones
[{Mn(3-Clpcyd)(2,2Ј-bpy)(S)}2(µ1,3-3-
Clpcyd)2], S ϭ MeOH or EtOH; the 1-D [Mn(2,2Ј-
bpy)(µ1,3-4-Clpcyd)2]n and the 2-D [Mn(µ1,3-3-Fpcyd)2(µ-
4,4Ј-bpy)]n, in which 4-bzpy is 4-benzoylpyridine, 2,2Ј-bpy
and 4,4Ј-bpy corresponds to the 2,2Ј- and 4,4Ј-bipyridyls.
This series of compounds was obtained by using different
X-phenylcyanamido derivatives: 3-ClpcydϪ, 4-ClpcydϪ and
3-FpcydϪ are the 3-chloro-, 4-chloro-, or 3-fluorophenylcy-
anamido ligands, respectively. Magnetic measurements on
the polynuclear µ1,3-X-pcydϪ compounds revealed moder-
ate AF coupling for all of them. This coupling lies in an
intermediate position between the typical magnitude of the
coupling induced by µ1,3 azido and µ1,5 dicyanamido
bridges. MO calculations have evaluated the influence of
the chair distortion of the MnϪ(NCN)2ϪMn unit, the ef-
fect of the halo substituent in the para position and the
torsion effect of the phenyl rings on the superexchange in-
teraction, and the theoretical results have been correlated
with the experimental data.
In this paper, bearing in mind that the number of com-
pounds is still low, we extend the study to the coordination
compounds derived from the X-phenylcyanamido ligands
by reporting the use of only the phenylcyanamido anion
(pcydϪ), to synthesise a new series of [Mn(pcyd)2(L)n] de-
rivatives which show different nuclearities and dimensional-
ities. Successful syntheses and structural characterisation
have been carried out for several representative complexes,
Scheme 1
[a]
´
`
Departament de Quımica Inorganica, Universitat de Barcelona,
´
`
c/ Martı Franques 1Ϫ11, 08028 Barcelona, Spain
Fax: (internat.) ϩ34-(0)93-4907725
E-mail: ramon.vicente@qi.ub.es
[b]
Institut für Physikalische und Theoretische Chemie, Technische
Universität Graz,
8010 Graz, Austria
E-mail: Mautner@ptc.tu-graz.ac.at
Eur. J. Inorg. Chem. 2004, 309Ϫ316
DOI: 10.1002/ejic.200300305
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
309

A. Escuer, N. Sanz, F. A. Mautner, R. Vicente
FULL PAPER
with formulae [Mn(pcyd)2(phen)2] (1), [{Mn(pcyd)(phen)- tion seems then to be pcydH Ͼ µ1,3-X-pcyd Ͼ N-nitrile co-
(MeOH)}2(µ1,3-pcyd)2]
MeOH (3·MeOH)
(2),
and
[Mn(4-bzpy)2(µ1,3-pcyd)2]· ordination or anionic X-pcydϪ. The limited data for MnII
[Mn(µ1,3-pcyd)2(µ-4,4Ј- derivatives suggest the above order, but further experimen-
bpy)]n·MeOH (4·MeOH) where 4-bzpy is 4-benzoylpyri- tal data are required to obtain a general assignment.
dine, 4,4Ј-bpy corresponds to 4,4Ј-bipyridyl and phen is Description of the Structure of [Mn(pcyd)2(phen)2] (1):
1,10-phenanthroline. These compounds were obtained by This compound consists of monomeric units in which the
reaction in alcoholic media of manganese salts with the cor- terminal pcydϪ ligands adopt a cis arrangement around the
responding pyridinic or bipyridinic ligands and the depro- central MnII ion (Figure 1). Selected bond parameters are
tonated phenylcyanamide. The X-ray crystal structure de- given in Table 1.
termination reveals a wide variety of topologies and supra-
molecular arrangements: compound 1 is a mononuclear
complex; compounds 2 a dinuclear complex bridged by
double phenylcyanamido ligands, giving a supramolecular
1-D system by means of hydrogen bonds; compound
3·MeOH is a chain of manganese atoms linked by double
phenylcyanamido bridges. Finally, compound 4·MeOH is a
2-D system formed by the crossing of phenylcyanamido and
4,4Ј-bpy chains. This paper gives the second structural set
of data for polynuclear phenylcyanamide bridged deriva-
tives with MnII as the central atom, together with a set of
new experimental variable temperature susceptibility data
for the µ1,3-X-pcydϪ superexchange mediator.
Magnetic measurements for compounds 2Ϫ4 reveal a
moderate AF coupling which lies in an intermediate posi-
tion between the typical values of the coupling induced by
µ1,3-azido and µ1,5-dicyanamido bridges. The obtained
Figure 1. Labelled plot of [Mn(pcyd)2(phen)2] (1)
coupling constants are in accordance with the general rules
˚
for the µ1,3 coordination mode of pcydϪ ligands discussed
Table 1. Selected bond lengths [A] and angles [°] for [Mn(pcyd)2-
(phen)2] (1)
in the previous paper.[5]
Mn(1)ϪN(1)
Mn(1)ϪN(4)
2.131(3) Mn(1)ϪN(3)
2.321(2)
71.3(1)
2.314(2)
N(1)ϪMn(1)ϪN(4 a)[a] 159.5(1)
N(3)ϪMn(1)ϪN(4)
Results and Discussion
Ϫ
N(1)ϪMn(1)ϪN(3)
N(1)ϪMn(1)ϪN(4)
N(1)ϪMn(1)ϪN(3 a)
N(1)ϪMn(1)ϪN(1 a)
N(1)ϪC(1)
N(2)ϪC(2)
Mn(1)ϪN(1)ϪC(1)
C(1)ϪN(2)ϪC(2)
107.2(1)
90.8(1)
88.9(1)
100.4(1)
N(3)ϪMn(1)ϪN(3 a) 155.2(1)
N(3)ϪMn(1)ϪN(4 a)
N(4)ϪMn(1)ϪN(4 a)
Ϫ
90.1(1)
84.1(1)
Ϫ
Infrared Spectra: Neutral pcydH shows a characteristic
IR ν(NCN) stretching absorption over a short wavenumber
range (2225Ϫ2249 cmϪ1), which shifts down to ca. 2120
cmϪ1 for deprotonated pcydϪ, suggesting a lower contri-
bution of the resonance form containing the nitrile frag-
ment. N-nitrile-coordinated X-pcydϪ ligands, exhibit inter-
mediate positions (always lower than 2200 cmϪ1), with a
dependence on the nature of the metallic centre and the
number of halo groups.[3] For pcydϪ, the signal appears at
2108 cmϪ1 for 1 (only N-nitrile-coordinated pcydϪ ligand),
Ϫ
Ϫ
Ϫ
1.154(5) C(1)ϪN(2)
1.388(6)
158.8(5)
121.7(4)
1.299(6)
171.5(5)
N(1)ϪC(1)ϪN(2)
[a]
Symmetry codes: a: Ϫx, y, Ϫz ϩ 1/2
Ϫ
The Mn2ϩ ion shows a strongly distorted octahedral en-
at 2168Ϫ2136 cmϪ1 for 2 (containing the two µ1,3-pcyd and vironment imposed by the rigidity of the 1,10-phenantroline
N-nitrile pcydϪ coordination modes) and at 2164 and 2133 ligands. The pcydϪ ligands are coordinated to the Mn atom
cmϪ1 for 3 and 4, respectively (containing the two µ1,3-X- by the nitrile N atoms. There are two kinds of bond MnϪN
pcydϪ coordination modes). The structurally characterised distances: a short distance of 2.131(3) A between the Mn
II
˚
µ1,3 copper dimer [{Cu(pcyd)(2,2Ј-bpy)}2(µ1,3-pcyd)2][6] is in ion and the nitrile N atoms, and longer distances to the
˚
reasonable agreement with this assignment: it exhibits two N(phen) atoms: Mn(1)ϪN(3) 2.312(2) A and Mn(1)ϪN(4)
similar absorptions at 2175 and 2103 cmϪ1. In the mononu- 2.314(2) A. The most distorted bond angles around the Mn
˚
clear compound with the 3-ClpcydϪ ligand [Mn(3- atom are N(3)ϪMnϪN(4), 71.3(1)°, N(1)ϪMnϪN(1 a),
Ϫ
Clpcyd)2(H2O)2(4-bzpy)2] the signal appears at 2108 cmϪ1 100.4(1)° and N(4)ϪMnϪN(4 a), 84.1(1)°. The coordi-
Ϫ
(only N-nitrile-coordinated pcydϪ ligand) and at nation of the monodentate phenylcyanamido ligand to the
2155Ϫ2132 cmϪ1 and 2159Ϫ2133 cmϪ1 in the dinuclear manganese atom is not linear with a Mn(1)ϪN(1)ϪC(1)
ones [{Mn(3-Clpcyd)(2,2Ј-bpy)(S)}2(µ1,3-3-Clpcyd)2], S ϭ bond angle of 158.8(5)°.
MeOH or EtOH, respectively (containing the two µ1,3
-
The NCN unit is practically linear with a N(1)ϪC(1)Ϫ
pcydϪ and N-nitrile pcydϪ coordination modes).[5] The N(2) angle of 171.5°. NCN is asymmetric, with bond
˚
wavenumber sequence for the ν(NCN) stretching absorp- lengths of N(1)ϪC(1) ϭ 1.154(5) A and C(1)ϪN(2) ϭ
310
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2004, 309Ϫ316

Phenylcyanamido Ligand Building Molecular, 1-D, and 2-D Systems
FULL PAPER
˚
1.299(6) A. The cyanamido unit is practically coplanar with The linked phen and the variety of ligands distorts the coor-
the phenyl group of the pcydϪ ligand and shows a dination polyhedron of the Mn atom: bond angles ranging
C(1)ϪN(2)ϪC(2) bond angle of 121.7(4)°.
between 72.1(1)° for N(5)ϪMn(1)ϪN(6) and 105.5(1)° for
Description of the Structure of [{Mn(pcyd)(phen)- N(2)ϪMn(1)ϪN(6) are found. The different nature of the
(MeOH)}2(µ1,3-pcyd)2] (2): The structure consists of centro- N atoms of the phenylcyanamido ligand also induces differ-
symmetric dinuclear Mn units linked by double end-to-end ent bond parameters in the bridging region: Mn(1)ϪN(1)
˚
phenylcyanamido bridges (Figure 2). Selected bond param- takes the value of 2.278(2) A whereas Mn(1)ϪN(1A) is only
˚
eters are given in Table 2.
2.166(2) A. MnϪNϪC bond angles are also different, being
Mn(1A)ϪN(1)ϪC(1)
156.2(2)°
in
contrast
with
Mn(1)ϪN(2)ϪC(1), which takes the value of 113.2(1)°. As
occurs in 1, the monodentate phenylcyanamido ligands co-
ordinate to the manganese atom in a quasi-linear arrange-
ment, with a Mn(1)ϪN(3)ϪC(9) bond angle of 160.3(1)°.
The CϪNϪC angles between the cyanamido and the
phenyl groups are similar for the terminal and the bridging
ligands: 117.2(2)° and 117.0(2)°, respectively. The
MnϪ(NCN)2ϪMn subunit shows a chair distortion similar
to those often found in similar systems with double azido
bridges.[1] This means that the two ϪNCNϪ groups are in
the same plane with the manganese atoms placed 0.403(1)
˚
A out of the main plane. The torsion angle between the
plane determined by the two ϪNCNϪ groups and the
N(2)ϪMn(1)ϪN(1A) plane is 14.7(1)°. The pcydϪ ligand is
practically planar with a minor torsion of 4.1(2)° between
the bond direction N(2)ϪC(2) and the (NCN)2 plane. The
phenylcyanamido ligand is placed out of the main (NCN)2
plane, which forms an acute angle of 15.7(1)° with the
N(2)ϪC(2) bond direction. The Mn···Mn intradimer dis-
Figure 2. Labelled plot of [{Mn(pcyd)(phen)(MeOH)}2(µ1,3
pcyd)2] (2)
-
˚
tance is 5.479(1) A.
The dinuclear units generate a supramolecular one-di-
mensional H-bonded system by means of the OH group of
the coordinated methanol molecules, O(1) atom, and the
N(4) atoms of the terminal pcydϪ ligands. Two of these H
bonds appear between each dinuclear unit, giving a struc-
turally alternating 1-D system (Figure 3). The N(4)ϪO(1)
˚
Table 2. Selected bond lengths [A] and angles [°] for [{Mn(pcyd)-
(phen)(MeOH)}2(µ1.3-pcyd)2] (2)
Mn(1)ϪO(1)
Mn(1)ϪN(2)
Mn(1)ϪN(3)
2.235(2)
2.278(2)
2.140(2)
Mn(1)ϪN(5)
Mn(1)ϪN(6)
Mn(1)ϪN(1A)
N(2)ϪMn(1)ϪN(3)
N(2)ϪMn(1)ϪN(5)
N(2)ϪMn(1)ϪN(6)
N(2)ϪMn(1)ϪN(1A)
N(5)ϪMn(1)ϪN(6)
N(5)ϪMn(1)ϪN(1A)
N(6)ϪMn(1)ϪN(1A)
2.306(2)
2.300(2)
2.166(2)
91.2(1)
92.8(1)
105.5(1)
88.5(1)
72.1(1)
91.4(1)
158.6(1)
˚
distance is 2.727(2) A and the bond angle O(1)ϪH(1)ϪN(4)
has a value of 178(3)°.
O(1)ϪMn(1)ϪN(2)
O(1)ϪMn(1)ϪN(3)
O(1)ϪMn(1)ϪN(5)
O(1)ϪMn(1)ϪN(6)
O(1)ϪMn(1)ϪN(1A)[a]
N(3)ϪMn(1)ϪN(5)
N(3)ϪMn(1)ϪN(6)
N(3)ϪMn(1)ϪN(1A)
N(1)ϪC(1)
175.1(1)
87.4(1)
89.8(1)
79.2(1)
87.4(1)
163.7(1)
91.6(1)
104.6(1)
1.167(3)
N(3)ϪC(9)
1.160(3)
1.289(3)
1.404(3)
160.3(1)
176.5(2)
117.2(2)
C(1)ϪN(2)
C(2)ϪN(2)
1.296(3)
1.413(3)
C(9)ϪN(4)
C(10)ϪN(4)
Mn(1A)ϪN(1)ϪC(1)
N(1)ϪC(1)ϪN(2)
C(1)ϪN(2)ϪMn(1)
Mn(1)ϪN(2)ϪC(2)
C(2)ϪN(2)ϪC(1)
156.2(2)
Mn(1)ϪN(3)ϪC(9)
N(3)ϪC(9)ϪN(4)
C(9)ϪN(4)ϪC(10)
176.4(2)
113.2(1)
129.2(1)
117.0(2)
Figure 3. Hydrogen bond chain in compound 2
[a]
Symmetry codes: (A) Ϫx, Ϫy, Ϫz ϩ 1.
Description of the Structure of [Mn(4-bzpy)2(µ1,3-pcyd)2]·
MeOH (3·MeOH): Selected bond parameters are given in
The six coordination sites around the Mn atoms are oc- Table 3. The structure consists of a one-dimensional Mn
cupied by the two N atoms of one phen ligand, one nitrile system where the coordination environment around the Mn
N atom of the terminal pcydϪ ligand, one nitrile and one atoms includes two N atoms of trans-4-bzpy ligands and
amido nitrogen atoms of the two bridging cyanamido li- four N atoms of bridging pcydϪ ligands. The compound
gands and one O atom of the solvent molecule (methanol). crystallizes with one MeOH molecule per formula unit.
Eur. J. Inorg. Chem. 2004, 309Ϫ316
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 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
311

A. Escuer, N. Sanz, F. A. Mautner, R. Vicente
Table 3. Selected bond lengths [A] and angles [°] for [Mn(4-bzpy)2(µ1.3-pcyd)2]·MeOH (3·MeOH)
FULL PAPER
˚
Mn(1)ϪN(1)
Mn(1)ϪN(2)
Mn(1)ϪN(3)
2.168(2)
2.305(3)
2.195(2)
Mn(1)ϪN(4)
Mn(1)ϪN(5)
Mn(1)ϪN(6)
N(3)ϪMn(1)ϪN(2)
N(3)ϪMn(1)ϪN(4)
N(3)ϪMn(1)ϪN(5)
N(3)ϪMn(1)ϪN(6)
N(4)ϪMn(1)ϪN(5)
N(4)ϪMn(1)ϪN(6)
N(5)ϪMn(1)ϪN(6)
2.272(3)
2.329(3)
2.275(3)
95.7(1)
88.3(1)
85.9(1)
86.5(1)
88.2(1)
95.9(1)
171.5(1)
N(1)ϪMn(1)ϪN(3)
N(1)ϪMn(1)ϪN(2)
N(1)ϪMn(1)ϪN(4)
N(1)ϪMn(1)ϪN(5)
N(1)ϪMn(1)ϪN(6)
N(2)ϪMn(1)ϪN(4)
N(2)ϪMn(1)ϪN(5)
N(2)ϪMn(1)ϪN(6)
N(1)ϪC(1)
175.5(1)
86.4(1)
89.0(1)
90.5(1)
97.4(1)
170.2(1)
83.2(1)
93.9(1)
1.166(4)
1.300(4)
1.413(4)
N(3)ϪC(8)
1.165(4)
1.301(4)
1.411(4)
141.9(2)
175.5(3)
110.5(2)
128.7(2)
117.9(3)
C(1)ϪN(2 a)[a]
C(8)ϪN(4 b)
Ϫ
Ϫ
N(2)ϪC(2)
N(4)ϪC(9)
Mn(1)ϪN(1)ϪC(1)
N(1)ϪC(1)ϪN(2 a)
142.3(2)
Mn(1)ϪN(3)ϪC(8)
N(3)ϪC(8)ϪN(4 b)
175.2(3)
109.0(2)
132.3(2)
116.6(2)
Ϫ
Ϫ
C(1)ϪN(2 a)ϪMn(1 a)
C(8)ϪN(4 b)ϪMn(1 b)
Ϫ
Ϫ
Ϫ
Ϫ
Mn(1)ϪN(2)ϪC(2)
Mn(1)ϪN(4)ϪC(9)
C(2)ϪN(2)ϪC(1 a)
C(9)ϪN(4)ϪC(8 b)
Ϫ
Ϫ
[a]
Symmetry codes: — a: Ϫx, Ϫy, Ϫz ϩ 1; — b: Ϫ x ϩ 1, Ϫy, Ϫz ϩ 1.
˚
Double cyanamido bridges link the Mn atoms, giving a 7.2(2)°, respectively. The Mn atoms are placed 0.048 A out
trans chain (Figure 4). The bond parameters in the bridging of the (NCN)2 plane in the Mn(1 b)Ϫ[N(3)Ϫ
Ϫ
region show different bond lengths for the MnϪN(nitrile) C(8)ϪN(4)]2ϪMn(1) dinuclear unit. The dihedral angle be-
˚
and the MnϪN(amide) unions: Mn(1)ϪN(1), 2.168(2) A tween N(3)ϪMn(1)ϪN(4) and the main (NCN)2 plane is
˚
˚
˚
and Mn(1)ϪN(3), 2.195(2) A; Mn(1)ϪN(2), 2.305(3) A, 36.1°. The Mn···Mn intrachain distance is 5.328(1) A,
˚
and Mn(1)ϪN(4), 2.272(3) A. The bond angle whereas the minimum interchain Mn···Mn distance is
˚
Mn(1 a)ϪN(2 a)ϪC(1), 109.0(2)° is clearly smaller than 8.520(1) A.
Mn(1)ϪN(1)ϪC(1), 142.3(2)°. The MnϪ(NCN)2ϪMn su-
bunits show an important chair distortion: for the bpy)]n·MeOH (4·MeOH): The use of 4,4Ј-bpy determines a
Ϫ
Ϫ
Description of the Structure of [Mn(µ1,3-pcyd)2(µ-4,4Ј-
Mn(1)Ϫ[N(1)ϪC(1)ϪN(2)]2ϪMn(1 a) ring the Mn atoms trans-octahedral arrangement around the Mn atoms (Fig-
Ϫ
˚
are placed 0.979(1) A out of the (NCN)2 main plane and ure 5). Selected bond parameters are given in Table 4.
there is
a
dihedral angle of 37.0(1)° between the
The compound crystallises with a MeOH molecule per
N(1)ϪMn(1)ϪN(2) plane and the main (NCN)2 plane. In formula unit. The coordination sites around the manganese
this case the deviation of the phenyl groups, given by the atom are occupied by two trans N atoms of two bridging
acute angle between the bond directions N(2)ϪC(2) or 4,4Ј-bpy ligands and by four bridging pcydϪ ligands. The
N(4)ϪC(9) and the (NCN)2 plane are only 9.6(2) and structure may then be described as a two-dimensional sys-
Figure 4. ORTEP plot of [Mn(4-bzpy)2(µ1,3-pcyd)2]·MeOH (3·MeOH) with thermal ellipsoids at the 40% probability level
312
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Phenylcyanamido Ligand Building Molecular, 1-D, and 2-D Systems
FULL PAPER
Figure 6. View of the 2-D arrangement of 4·MeOH by means of
the pcyd and 4,4Ј-bipy bridging ligands
˚
˚
Mn(2)ϪN(4) are 2.315(4) A and 2.327(4) A, respectively.
Bond angles related to the nitrile atom
Figure 5. ORTEP plot of the basic unit of [Mn(µ1,3-pcyd)2(µ-4,4Ј-
bpy)]n·MeOH (4·MeOH) with thermal ellipsoids at the 50% prob-
ability level
N
Mn(1)ϪN(3)ϪC(8), 148.9(5)° and Mn(2)ϪN(1)ϪC(1),
142.3(4)° are larger than the angles related to the amide N
tem with 4,4Ј-bpy-Mn chains crossed by Mn-pcyd chains atom Mn(1)ϪN(2)ϪC(1), 111.7(3)° and Mn(2)ϪN(4)Ϫ
(Figure 6).
C(8), 111.2(3)°. As occurs for the above compounds,
The bond lengths in the bridging region again show a MnϪ(NCN)2ϪMn subunits show a clear chair distortion
˚
clear difference between nitrile and amide N atoms of the with the Mn atoms placed 0.808(1)Ϫ0.942(1) A out of the
ligand: bond lengths for Mn(1)ϪN(3) and Mn(2)ϪN(1) are cyanamido plane. A dihedral angle of 30.6(2)Ϫ34.3(2)° is
˚
˚
2.187(4) A and 2.173(3) A whereas Mn(1)ϪN(2) and found between the (NCN)2 planes and N(1)ϪMn(2)ϪN(4)
˚
Table 4. Selected bond lengths [A] and angles [°] for [Mn(µ1.3-pcyd)2(µ-4.4Ј-bpy)]n·MeOH (4·MeOH)
Mn(1)ϪN(5)
2.350(7)
2.279(7)
2.315(4)
2.187(4)
Mn(2)ϪN(7)
2.301(7)
2.312(7)
2.173(3)
2.327(4)
Mn(1)ϪN(6 b)[a]
Mn(2)ϪN(8 a)
Ϫ
Ϫ
Mn(1)ϪN(2)
Mn(1)ϪN(3)
Mn(2)ϪN(1)
Mn(2)ϪN(4)
N(5)ϪMn(1)ϪN(6 b)
N(5)ϪMn(1)ϪN(2)
N(5)ϪMn(1)ϪN(3)
180.0(6)
N(7)ϪMn(2)ϪN(8 a)
N(7)ϪMn(2)ϪN(1)
N(7)ϪMn(2)ϪN(4)
180.0(1)
Ϫ
Ϫ
87.6(1)
92.4(2)
87.6(1)
92.4(2)
92.4(1)
87.6(2)
92.4(1)
87.6(2)
84.8(1)
175.2(2)
95.4(1)
95.4(1)
175.2(1)
84.8(1)
91.7(1)
82.8(1)
91.7(1)
82.8(1)
88.3(1)
97.2(1)
88.3(1)
97.2(1)
88.8(1)
176.7(2)
91.6(1)
91.6(1)
165.3(1)
88.8(1)
N(5)ϪMn(1)ϪN(2 e)
N(7)ϪMn(2)ϪN(1 f)
Ϫ
Ϫ
N(5)ϪMn(1)ϪN(3 e)
N(7)ϪMn(2)ϪN(4 f)
Ϫ
Ϫ
N(6 b)ϪMn(1)ϪN(2)
N(8 a)ϪMn(2)ϪN(1)
Ϫ
Ϫ
N(6 b)ϪMn(1)ϪN(3)
N(8 a)ϪMn(2)ϪN(4)
Ϫ
Ϫ
N(6 b)ϪMn(1)ϪN(2 e)
N(8 a)ϪMn(2)ϪN(1 f)
Ϫ
Ϫ
Ϫ
Ϫ
Ϫ Ϫ
N(6 b)ϪMn(1)ϪN(3 e)
N(8 a)ϪMn(2)ϪN(4 f)
Ϫ
Ϫ
N(2)ϪMn(1)ϪN(3)
N(1)ϪMn(2)ϪN(4)
N(2)ϪMn(1)ϪN(2 e)
N(1)ϪMn(2)ϪN(1 f)
Ϫ
Ϫ
N(2)ϪMn(1)ϪN(3 e)
N(1)ϪMn(2)ϪN(4 f)
Ϫ
Ϫ
N(3)ϪMn(1)ϪN(2 e)
N(4)ϪMn(2)ϪN(1 f)
Ϫ
Ϫ
N(3)ϪMn(1)ϪN(3 e)
N(4)ϪMn(2)ϪN(4 f)
Ϫ
Ϫ
N(2 e)ϪMn(1)ϪN(3 e)
N(1 f)ϪMn(2)ϪN(4 f)
Ϫ
Ϫ
Ϫ
Ϫ
N(3)ϪC(8)
1.175(6)
N(1)ϪC(1)
1.162(6)
C(8)ϪN(4)
N(4)ϪC(2)
1.278(6)
1.429(7)
C(1)ϪN(2)
N(2)ϪC(9)
1.299(6)
1.413(7)
Mn(1)ϪN(3)ϪC(8)
N(3)ϪC(8)ϪN(4)
C(8)ϪN(4)ϪMn(2)
Mn(2)ϪN(4)ϪC(2)
C(8)ϪN(4)ϪC(2)
148.9(5)
Mn(2)ϪN(1)ϪC(1)
N(1)ϪC(1)ϪN(2)
C(1)ϪN(2)ϪMn(1)
Mn(1)ϪN(2)ϪC(9)
C(9)ϪN(2)ϪC(1)
142.3(4)
174.4(5)
111.2(3)
128.6(3)
116.0(4)
177.1(6)
111.7(3)
132.5(3)
115.8(4)
[a]
Symmetry codes — a: x, y Ϫ 1, z; — b: x, y ϩ 1, z; — e: x, y, Ϫz Ϫ 1; — f: x, y, Ϫz.
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 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
313

A. Escuer, N. Sanz, F. A. Mautner, R. Vicente
FULL PAPER
or N(3)ϪMn(1)ϪN(2) planes. Bridging phenylcyanamido
EPR spectra for compound 1 show an isotropic broad
ligands are far from planar, showing torsion angles for band with a peak-to-peak increment (∆pp) of 674 G at room
N(3)ϪN(4)ϪC(2)ϪC(3) of 38.7(4)° and N(1)ϪN(2)Ϫ temperature, centred at g ϭ 2.00. At 4 K the spectrum exhi-
C(9)ϪC(10) of 7.7(3)°.
bits the main signal centred at g ϭ 2.00 and a second
In this case, a small deviation of the phenyl groups is weaker half-field band displaced at g ϭ 4.21. Compound 2
evidenced by the 26.5(3)° or 0.8(3)° acute angles between shows one isotropic broad band at room temperature and
the bond directions N(2)ϪC(9) or N(4)ϪC(2) with the ref- 77 K, centred at room temperature at g ϭ 2.01 with ∆pp of
erence (NCN)2 plane. The Mn···Mn distance through the 286 G. At 4 K the spectrum exhibits two main signals
˚
cyanamido unit is 5.407(1) A, through the 4,4Ј-bpy bridge centred at g ϭ 2.01 and 10.27 with ∆pp of 438 G and 595
˚
11.712(1) A, and the minimum interplane Mn···Mn dis- G, respectively, and several signals with minor intensities,
˚
tance is 10.289(1) A.
which indicate some anisotropic effect at very low tempera-
Magnetic Measurements and Coupling Constant Calcu- tures. Spectra of compounds 3 and 4 correspond nicely to
lations: Magnetic measurements were performed for com- that expected for one-dimensional systems with moderate
pounds 2Ϫ4 in the 300Ϫ4 K temperature range on pow- antiferromagnetic coupling and weak dipolar interactions
[8]
˚
dered crystalline samples, (see Exp. Sect.). The overall inter- (Mn···Mn distances around 5.5 A). Between room tem-
action is moderately antiferromagnetic in all cases.
perature and 77 K the isotropic signals centered at g ϭ 2.01
The susceptibility plots increase gradually on cooling for show a ∆pp of 94 G and 92 G, respectively. Analogous MnII
compound 2 (Figure 7), but don’t reach a maximum be- doubly bridged chains with end-to-end azido ligands with
cause at low temperatures a low quantity of impurities pro- similar Mn···Mn intrachain distances have J values that
duce a sudden increase in the susceptibility value. The ex- typically lie around Ϫ10 cmϪ1, the peak-to-peak linewidth
perimental data were analysed with the analytical ex- being only 35 G due to the greater superexchange nar-
pression for an isotropic S ϭ 5/2 dinuclear compound by rowing.[9] Instead, for weaker coupling, doubly dca bridged
using the analytical expression derived from the isotropic MnII chains, the peak-to-peak linewidth is much greater re-
Hamiltonian H ϭ ϪJS1·S2, including an impurity term. aching values around 100Ϫ120 G[6] that show dipolar
The best fit parameters were J ϭ Ϫ3.5(1) cmϪ1, g ϭ broadening on cooling down to 4 K.
2.01(1), ρ ϭ 0.030.
The efficiency in transmitting the superexchange interac-
Ϫ [5]
Magnetic susceptibilities for compounds 3 and 4 also in- tions is in the order N3Ϫ Ͼ X-pcydϪ ϾϾ N(CN)2
with
crease on cooling, reaching a broad maximum at 16 K in typical values of the J parameter in the 1-D systems being
compound 4 (Figure 7). For compound 3 a sudden increase around Ϫ7/Ϫ15 cmϪ1 (azido), Ϫ1/Ϫ3 cmϪ1 (X-pcydϪ) and
is also observed in the susceptibility values due to paramag- weaker than Ϫ0.5 cmϪ1 for dicyanamide. The new series of
netic impurities. The coupling through the 4,4Ј-bpy bridges J values reported here for the polynuclear phenylcyanamide
is negligible, so 2-D compound 4 should be assumed to be bridged derivatives with MnII as the central atom confirms
magnetically one-dimensional through the phenylcyanam- the assumption.
ido bridges. The experimental data were analysed with the
analytical expression for an isotropic S ϭ 5/2 chain sys-
tem[7] derived by Fisher from the Hamiltonian H ϭ
ΣϪJSi·Siϩ1, including an impurity term for 3. The best fit
parameters were J ϭ Ϫ2.7(1) cmϪ1, g ϭ 2.00(1), ρ ϭ 0.027
and J ϭ Ϫ2.1(1) cmϪ1, g ϭ 2.00(1) for 3 and 4, respectively.
Conclusion
The ability of the X-phenylcyanamido ligands to act as
bridging ligands has been newly confirmed by using the
phenylcyanamido anion (pcydϪ) to synthesise a new series
of formula [Mn(pcyd)2(L)n], L ϭ phen, 4-bzpy and 2,2Ј-
bpy, which show different nuclearities and dimensionalities.
The coordination mode of the bridging pcydϪ ligands is
µ1,3. The magnetic measurements indicate AF coupling.
The obtained coupling constant values are intermediate be-
tween the equivalent values for azido and dicianamido
bridging ligands.
Experimental Section
Physical Methods: Magnetic susceptibility measurements were car-
ried out on polycrystalline samples with a DSM8 pendulum suscep-
tometer working in the range 4Ϫ300 K under magnetic fields of
approximately 1 T. Diamagnetic corrections were estimated from
Pascal tables. The infrared spectra (4000Ϫ400 cmϪ1) were recorded
from KBr pellets with a Nicolet 520 FTIR spectrophotometer. EPR
spectra were recorded with a Bruker ES200 spectrometer at X-
band frequency.
Figure 7. Plot of χM vs T for compounds [{Mn(pcyd)(phen)-
(MeOH)}2(µ1,3-pcyd)2] (2) (solid circles) [Mn(4-bzpy)2(µ1,3-pcyd)2]n
(3) (open squares) and [Mn(µ1,3-pcyd)2(µ-4,4Ј-bpy)]n (4) (solid
squares). Solid line shows the best fit of the data (see text)
314
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Eur. J. Inorg. Chem. 2004, 309Ϫ316

Phenylcyanamido Ligand Building Molecular, 1-D, and 2-D Systems
FULL PAPER
Table 5. Crystal data and structure refinement for [Mn(pcyd)2(phen)2] (1), [{Mn(pcyd)(phen)(MeOH)}2(µ1,3-pcyd)2] (2), [Mn(4-bzpy)2(µ1,3
pcyd)2]n·MeOH (3·MeOH) and [Mn(µ1,3-pcyd)2(µ-4,4Ј-bpy)]n·MeOH (4·MeOH)
-
1
2
3·MeOH
4·MeOH
Empirical formula
Mw
C38H26MnN8
649.61
Pbcn
13.176(5)
10.165(4)
23.530(8)
90
C54H44Mn2N12O2
1002.89
C2/c
15.758(6)
13.771(4)
22.753(7)
90
93.49(2)
90
4928(3)
4
C39H32MnN6O3
687.7
P1
C25H22MnN6O
477.43
C2
18.498(4)
11.712(2)
10.472(2)
90
106.43(3)
90
2176.0(7)
4
¯
Space group
˚
a, A
10.043(3)
12.840(3)
14.448(5)
112.29(2)
90.96(2)
101.10(2)
1683(1)
2
˚
b A
˚
c, A
α, deg.
β, deg.
γ, deg.
90
90
3
˚
V, A
Z
3151.5(20)
4
T, °C
25(2)
0.71069
1.369
0.461
0.0486
0.1431
Ϫ185(2)
0.71069
1.352
0.567
0.0376
0.0926
Ϫ173(2)
0.71069
1.357
0.440
0.0522
Ϫ185(2)
0.71069
1.457
0.638
0.0478
0.1197
˚
λ(Mo-Kα), A
ρcalcd., g·cmϪ3
µ(Mo-Kα), mmϪ1
R[a]
ωR2[b]
0.1309
[a]
[b]
R(Fo) ϭ ΣFo Ϫ Fc/ΣFo. ωR (Fo)2 ϭ {Σ[ω[(Fo)2 Ϫ (Fc)2]2]/Σ[ω[(Fo)4]}1/2
.
Synthesis: Neutral phenylcyanamide (pcydH) was prepared by de-
sulfurisation of the phenylthiourea with lead acetate, following the
described general synthetic procedure.[11]
on a modified STOE 4-circle diffractometer with graphite-monoch-
romated Mo-Kα radiation (λ ϭ 0.71069 A) and the ω-scan tech-
˚
nique. Data of 1Ϫ4·MeOH were collected at room temperature,
Ϫ185(2) °C, Ϫ173(2) °C and Ϫ185(2) °C, respectively, and pro-
cessed in the usual way. The structures were solved by direct meth-
ods using the SHELXS-86 computer program,[12] and refined by
full-matrix least-squares methods on F2, using the SHELXL-93
program[13] incorporated in the SHELXTL/PC V 5.03 program li-
brary[14] and the graphics program PLUTON.[15] All non-hydrogen
atoms were refined anisotropically. Hydrogen atoms bonded to do-
nor atoms were located from difference Fourier maps, and the re-
maining ones were located on calculated positions by using the
HFIX utility of the SHELXL-93 program. Selected bond param-
eters are given in Table 1Ϫ4 for compounds 1Ϫ4·MeOH, respec-
tively. CCDC-201204 (1), -201205 (2), -201206 (3·MeOH) and
-201207 (4·MeOH) contain the supplementary crystallographic
data for this paper. These data can be obtained free of charge at
www.ccdc.cam.ac.uk/conts/retrieving.html [or from the Cambridge
Crystallographic Data Centre, 12, Union Road, Cambridge
Compound 1: 1 was prepared by reaction of a solution of manga-
nese nitrate hexahydrate (1 mmol) and 1,10-phenanthroline
(2 mmol) in 40 mL of methanol with a solution of pcydH (2 mmol)
in 10 mL of NaOH (0.2 ) to deprotonate the ligand. After the
reagents were mixed, the resulting clear solution was evaporated,
giving a yellow crystalline compound suitable for X-ray measure-
ments in a few days. Yield 21%. C38H26MnN8 (649.6): calcd. C
70.3, H 4.0, N 17.2; found C 69.8, H 4.0, N 17.5.
Compound 2: 2 was prepared by reaction of a solution of manga-
nese nitrate hexahydrate (1 mmol) and 1,10-phenanthroline
(1 mmol) in 40 mL of methanol with a solution of pcydH (2 mmol)
in 5 mL of NaOH (0.2 ) to deprotonate the ligand. After the
reagents were mixed, the resulting clear solution was evaporated,
giving a yellow crystalline compound suitable for X-ray measure-
ments in three days. Yield 44%. C54H44Mn2N12O2 (1002.9): calcd.
C 64.7, H 4.4, N 16.8; found C 63.7, H 4.2, N 16.7.
CB2 1EZ, UK; Fax: (internat.)
deposit@ccdc.cam.ac.uk].
ϩ 44-1223/336-033; E-mail:
Compounds 3 and 4: The method was the same as that for com-
pound 2, using 4-benzoylpyridine (2 mmol) for 3 and 4,4Ј-bipyri-
dine (1 mmol) for 4 instead of phenanthroline (1 mmol). Yield of
the corresponding yellow products, was 13% and 34%, respectively.
Elemental analyses were performed on 3 and 4 in powdered
samples three weeks after their preparation. Compound 3:
C38H28MnN6O2 (655.6): calcd. C 69.6, H 4.3, N 12.8; found C 68.5,
H 4.4, N 12.8. Compound 4: C24H18MnN6 (445.4): calcd. C 64.7,
H 4.1, N 18.9; found C 64.4, H 4.2, N 18.9. The elemental analysis
for 3 and 4 indicates the absence of crystallisation of MeOH mol-
ecules in the powdered samples. To avoid errors in the magnetic
measurements, the corresponding samples of 2 were freshly ex-
tracted from the mother solutions, dried and powdered just prior
to performing the measurements. Moreover, the samples of 3 and
4 were dried and powdered some days before performing the mag-
netic measurements.
Acknowledgments
A.E., R.V., and N.S. wish to thank the Ministerio de Ciencia y
´
Tecnologıa (Spain), project BQU2000/0791 for the financial sup-
port to carry out this research. F.A.M. wishes to thank Prof. Belaj
and Prof. Kratky (University of Graz) for the use of experimental
equipment and OENB (project 7967) for financial support.
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Eur. J. Inorg. Chem. 2004, 309Ϫ316
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FULL PAPER
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316
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Eur. J. Inorg. Chem. 2004, 309Ϫ316