Two different coordination geometries in polynuclear manganese(II) complexes with bis(μ-phosphinato) bridges

Article abstract of DOI:10.1016/j.poly.2012.07.028

Four new polynuclear phosphinato-bridged manganese(II) complexes, three dinuclear compounds [Mn(μ-dpp)(5-dmbpy)(NO₃)]₂ (1), [Mn(μ-dpp)(Me-phen)(NO₃)]₂ (2), [Mn(μ-bmp) (neocuproine)(NO₃)]₂ (3) and a 1D compound [Mn(μ-bmp)₂]_n (4) where Hdpp is diphenylphosphinic acid, Hbmp is bis(4-methoxyphenyl)phosphinic acid, 5-dmbpy = 5,5′-dimethyl-2,2′-dipyridyl, Me-phen = methyl-1,10-phenanthroline and neocuproine = 2,9-dimethyl-1,10-phenanthroline, have been synthesized and structurally characterized by X-ray crystallography. In this series, the dinuclear structures consist in a bis(diphenylphosphinato) (dpp) or a bis(4-methoxyphenyl)phosphinato (bmp) anion bridging the two Mn(II) centers in a syn-syn coordination mode for 1-3. The monodimensional compound 4 is built from double bridging syn-syn bis(4-methoxyphenyl)phosphinato anions. The coordination geometry around the Mn(II) ions in 1-3 is six-coordinate with distorted octahedral environment. Moreover, the coordination geometry around the Mn(II) ions in 4 is tetrahedral. The magnetic behavior of these complexes is reported. The complexes show weak antiferromagnetic coupling with J in the range 0.05-0.43 cm^-1 for 1-3 and 0.88 cm^-1 for 4. The magnetic properties are discussed in relation to the structural data.

Full text of DOI:10.1016/j.poly.2012.07.028

Polyhedron xxx (2012) xxx–xxx
Contents lists available at SciVerse ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Two different coordination geometries in polynuclear manganese(II)
complexes with bis(l-phosphinato) bridges
b
b
b
c
Franz A. Mautner a, , Miquel Navarro , Saskia Speed , M. Salah El Fallah , Mercè Font-Bardia ,
⇑
Ramon Vicente b,
⇑
a Institut für Physikalische and Theoretische Chemie, Technische Universität Graz, A-8010 Graz, Austria
b Departament de Química Inorgànica, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain
c Departament de Cristalꢀlografia i Mineralogia, Universitat de Barcelona, Martí i Franquès s/n, 08028-Barcelona, Spain
a r t i c l e i n f o
a b s t r a c t
Article history:
Available online xxxx
Four new polynuclear phosphinato-bridged manganese(II) complexes, three dinuclear compounds
[Mn(l
-dpp)(5-dmbpy)(NO3)]2 (1), [Mn(l-dpp)(Me-phen)(NO3)]2 (2), [Mn(l-bmp)(neocuproine)(NO3)]2
(3) and
a
1D compound [Mn( -bmp)2]n (4) where Hdpp is diphenylphosphinic acid, Hbmp is
l
This work is dedicated to Alfred Werner,
who opened the door to an immense,
exciting and still only superficially explored
world.
bis(4-methoxyphenyl)phosphinic acid, 5-dmbpy = 5,50-dimethyl-2,20-dipyridyl, Me-phen = methyl-1,
10-phenanthroline and neocuproine = 2,9-dimethyl-1,10-phenanthroline, have been synthesized and
structurally characterized by X-ray crystallography. In this series, the dinuclear structures consist in a
bis(diphenylphosphinato) (dpp) or a bis(4-methoxyphenyl)phosphinato (bmp) anion bridging the two
Mn(II) centers in a syn–syn coordination mode for 1–3. The monodimensional compound 4 is built from
double bridging syn–syn bis(4-methoxyphenyl)phosphinato anions. The coordination geometry around
the Mn(II) ions in 1–3 is six-coordinate with distorted octahedral environment. Moreover, the coordina-
tion geometry around the Mn(II) ions in 4 is tetrahedral. The magnetic behavior of these complexes is
reported. The complexes show weak antiferromagnetic coupling with J in the range 0.05–0.43 cmꢁ1 for
1–3 and 0.88 cmꢁ1 for 4. The magnetic properties are discussed in relation to the structural data.
Ó 2012 Elsevier Ltd. All rights reserved.
Keywords:
Manganese(II) complexes
Dinuclear complexes
1D complex
Phosphinato bridged
Crystal structure
Magnetic properties
1. Introduction
2.11 coordination mode. All of them were weakly antiferromagnet-
ically coupled according with the described observation that the
ꢁ
The RR0PO2 phosphinato ligands can be an alternative for the
carboxylate ligands in the synthesis of SMM compounds: manga-
nese polymetallic cages with phosphinato and phosphonato li-
gands simultaneously but no slow magnetic relaxation [1]
together with several Mn-RR0phosphinato cages with SMM behav-
ior [2–4] have been yet reported. The RR’PO2ꢁ phosphinato ligands,
besides to be terminal ones, can act as bridging ligands through
few coordination modes (Fig. 1) taking into account that only up
to two oxygen atoms can act as coordinating atoms. Usually they
l
-O,O0 O–P–O bridges give rise to low exchange interactions
[17,18]. The found |J| values were tentatively correlated with the
planarity of the dinuclear central eight membered ring [Mn(1)–
O(1)–P(1)–O(2)–]2: more planar, higher |J| value [10]. In this work,
with the aim to increase the number of examples for the structure-
coupling constant correlation, we explore the use of the anionic
derivatives of two phosphinic acids, Hbmp and the structurally
similar diphenylphosphinic acid (Hdpp), to generate new dinuclear
manganese(II) compounds with
synthesized three new dinuclear compounds: [Mn(
(5-dmbpy)(NO3)]2 (1), [Mn( -dpp)(Me-phen)(NO3)]2 (2) and
[Mn(
-bmp)(neocuproine)(NO3)]2 (3), 5-dmbpy = 5,50-dimethyl-
L
chelate ligands. We have
can be found as
l
-O,O0-bridges (2.11 coordination mode in the
l-dpp)
Harris notation [5,6]) in polynuclear compounds [1–2,4–10], even
though some examples of polynuclear transition metals with
3.21 [11–14] and 4.22 [15,16] coordination modes for phosphinato
bridging ligands have been also reported (Fig. 1).
In a previous work [10] we have reported three compounds
with general formula [Mn(l-bmp)(L)(NO3)]2, L = bidentate chelate
l
l
2,20-dipyridyl, Me-phen = methyl-1,10-phenanthroline and neo-
cuproine = 2,9-dimethyl-1,10-phenanthroline (see Scheme S1 in
supplementary material for the molecular structures of the ligands
and phosphinic acids discussed in the manuscript). The phosphina-
to bridging ligands in the new dinuclear compounds show the 2.11
coordination mode and the skeleton is similar to the previously re-
ported [10]. The magnetic properties of 1–3 are reported. All of
them are weakly antiferromagnetically coupled according
[10,16,17]. In the dinuclear compounds 1–3 the found |J| values
can be tentatively correlated with the planarity of the dinuclear
ligand, Hbmp = bis(4-methoxyphenyl)phosphinic acid, where the
phosphinato bridging ligands in all three compounds show the
⇑
Corresponding author. Tel.: +34 934039134; fax: +34 934907725.
E-mail addresses: mautner@ptc.tu-graz.ac.at (F.A. Mautner), ramon.vicente@
qi.ub.es (R. Vicente).
0277-5387/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.poly.2012.07.028
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2
F.A. Mautner et al. / Polyhedron xxx (2012) xxx–xxx
858 (m), 759 (m), 725 (vs), 700 (s), 562 (vs), 539 (s) (dpp); 1463
(s), 1437 (s), 1426 (s) (Mephen) and 1384 (s) (NO3).
2.2.3. [Mn(l-bmp)(neocuproine)(NO3)]2 (3)
To a solution of Mn(II) nitrate hexahydrate (0.151 g, 0.53 mmol)
in methanol was added neocuproine (2,9-dimethyl-1,10-phenan-
throline) (0.107 g, 0.51 mmol), bis(4-methoxyphenyl)phosphinic
acid (Hbmp) (0.139 g, 0.50 mmol) and triethylamine (0.5 mmol).
After two weeks of slow evaporation compound 3 was obtained
as yellow prism crystals. Anal. Calc. for C57H55Mn2P2N6O15: C,
55.34; H, 4.32; N, 6.86. Found: C, 55.4; H, 4.4; N, 6.8%. Selected
IR bands (cmꢁ1): 3434 (br) (st. –OH); 1295 (m), 1251 (m), 1197
(m), 1127 (s), 1049 (m), 1030 (m), 803 (m), 549 (m) (bmp); 1504
(m) (neocuproine) and 1384 (vs) (NO3).
Fig. 1. Coordination modes for the bridging phosphinate ligands.
central eight membered ring [Mn(1)–O(1)–P(1)–O(2)–]2: more
planar, higher |J| value [10].
On the other hand, we have prepared the 1D compound [Mn
(l-bmp)2]n (4) which is built from double bridging syn–syn bis
2.2.4. [Mn(l-bmp)2]n (4)
To a solution of Mn(II) perchlorate hydrate (0.255 g, 1.0 mmol)
in methanol was added salicylaldoxime (salox) (0.138 g,
(4-methoxyphenyl)phosphinato anions. The coordination of the
manganese(II) ions is tetrahedral, yielding a non usual chain of
Mn(II)O4 tetrahedra. The magnetic properties of 4, which show
antiferromagnetic coupling, are also reported.
1.0 mmol),
bis(4-methoxyphenyl)phosphinic
acid
(Hbmp)
(0.278 g, 1.0 mmol) and triethylamine (1 mmol). After a few days
compound 4 was obtained as light-yellow prism crystals. Anal.
Calc. for C28H28MnP2O8: C, 54.10; H, 4.78. Found: C, 55.2; H, 4.6%.
Selected IR bands (cmꢁ1): 3427 (br) (st. –OH); 1295 (m), 1256
(m), 1149 (s), 1133 (vs), 1061 (m), 1024 (m), 823 (m), 803 (m),
670 (m), 546 (s) (bmp) and 1133 (vs), 725 (m) (ClO4).
2. Experimental
2.1. Materials and methods
The compounds were purchased from Aldrich Chem. Co. All
other materials were reagent grade quality. Infrared spectra
(4000–400 cmꢁ1) were recorded from KBr pellets on a Perkin–
Elmer 380-B spectrophotometer. Elemental analyses were
performed at the Scientific-Technical services of the University of
Barcelona. Magnetic susceptibility measurements under a mag-
netic field of 0.3 T in the temperature range 2–300 K and magneti-
zation measurements in the field range of 0–5 T were performed
with a Quantum Design MPMS-XL SQUID magnetometer at the
Magnetochemistry Service of the University of Barcelona. All mea-
surements were performed on polycrystalline samples. Pascal’s
constants were used to estimate the diamagnetic corrections,
which were subtracted from the experimental susceptibilities to
give the corrected molar magnetic susceptibilities.
2.3. Crystal structure analysis
The X-ray single-crystal data of compounds 1, 3 and 4 were col-
lected on a Bruker-AXS SMART APEX CCD diffractometer and for 2
on a MAR345 diffractometer with image plate detector. The crys-
tallographic data, conditions retained for the intensity data collec-
tion and some features of the structure refinements are listed in
Table 1. Intensities were collected with graphite-monochromated
Mo Ka radiation (k = 0.71073 Å). Lorentz-polarization and absorp-
tion corrections using the SADABS computer program [19] were ap-
plied. The structures were solved by direct methods using the
SHELXS-97 [20] computer program, and refined by full-matrix
least-squares methods on F2, using the SHELXL-97 [20] program
incorporated in the SHELXTL [20] program package. All non-hydrogen
atoms were refined anisotropically. Hydrogen atoms were located
on calculated positions, and their isotropic displacement factors
were set 1.2 (or 1.5) times the value of the equivalent isotropic dis-
placement parameter of the parent atom. The molecular plots were
obtained using XP [18] and Mercury programs [21].
2.2. Synthesis of the compounds
2.2.1. [Mn(l-dpp)(5-dmbpy)(NO3)]2 (1)
To a solution of Mn(II) nitrate hexahydrate (0.155 g, 0.54 mmol)
in methanol was added 5-dmbpy (5,50-dimethyl-2,20-dipyridyl)
(0.096 g, 0.52 mmol), diphenylphosphinic acid (Hdpp) (0.117 g,
0.54 mmol) and triethylamine (1 mmol). A yellow precipitate was
obtained one week later. It was then recrystallized in CH2Cl2 and
layered in hexane. After two weeks compound 1 was obtained as
yellow prism crystals. Anal. Calc. for C48H44Mn2P2N6O14: C, 55.61;
H, 4.28; N, 8.11%. Found: C, 55.2; H, 4.3; N, 8.3%. Selected IR bands
(cmꢁ1): 3434 (br) (st. –OH); 1291 (m), 1207 (m), 1195 (m), 1133
(s), 1059 (m), 726 (m), 705 (m), 557 (s), 543 (m) (dpp); 1486
(m), 1437 (m) (5-dmbpy) and 1384 (vs) (NO3).
3. Results and discussion
3.1. Synthetic discussion
Compounds 1–3 of general formula [Mn(l-phos)(L)(NO3)]2,
phos = phosphinate and L = blocking ligand) were obtained by
mixing the stoichiometric quantities of manganese(II) nitrate
(1 mmol), phosphinic acid (1 mmol), chelate ligand (1 mmol) and
trietylamine (1 mmol) in methanol in the same predictable way
that was used by us in reference [10]. Compound 4 of formula
2.2.2. [Mn(
l-dpp)(Me-phen)(NO3)]2 (2)
[Mn(l-bmp)2]n was obtained by mixing the stoichiometric quanti-
To a solution of Mn(II) nitrate hexahydrate (0.168 g, 0.58 mmol)
in 60 ml of methanol was added Me-phen (methyl-1,10-phenan-
throline) (0.097 g, 0.52 mmol), diphenylphosphinic acid (Hdpp)
(0.109 g, 0.50 mmol) and triethylamine (0.5 mmol). After two
weeks compound 2 was obtained as yellow prism crystals. Anal.
Calc. for C50H40Mn2N6O10P2: C, 56.82; H, 3.79; N, 7.95. Found: C,
56.3; H, 3.8; N, 7.8%. Selected IR bands (cmꢁ1): 3427 (br) (st. –
OH); 1305 (s), 1198 (s), 1132 (s), 1052 (s), 1031 (m), 998 (m),
ties of manganese(II) perchlorate (1 mmol), bis(4-methoxy-
phenyl)phosphinic acid (1 mmol), salicylaldoxime (1 mmol) and
trietylamine (1 mmol). In this case we have used not a neutral
chelate ligand but a ligand which needs to be deprotonated
(salicylaldoxime). Probably, the low stoichiometric quantity of
trietylamine (only 1 mmol to deprotonate 1 mmol of salicyl-
aldoxime and 1 mmol of phosphinic acid) is the cause of the not
presence of salicylaldoximate in the final product 4.
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F.A. Mautner et al. / Polyhedron xxx (2012) xxx–xxx
3
Table 1
Crystallographic data and processing parameters.
Compound
1
2
3
4
Empirical formula
Formula mass
T (K)
System
Space group
C
48H44Mn2N6O10P2
C50H40Mn2N6O10P2
1056.70
293(2)
monoclinic
P21/c
C57H56Mn2N6O15P2
1236.90
100(2)
monoclinic
C2/c
C112H113Mn4O32.50P8
2446.55
100(2)
1036.71
100(2)
triclinic
triclinic
ꢀ
ꢀ
P1
P1
a (Å)
b (Å)
c (Å)
11.2638(12)
11.9899(12)
17.3669(14)
82.279(7)
87.837(8)
83.956(8)
2310.6(4)
2
12.595(4)
12.158(3)
18.009(5)
90
119.956(19)
90
2389.3(12)
2
0.661
15.2770(11)
18.3853(14)
20.861(2)
90
105.995(7)
90
5632.4(8)
4
0.579
12.2919(12)
15.6102(13)
17.8941(15)
111.073(14)
95.050(12)
112.847(14)
2847.2(7)
1
a
(°)
b (°)
c
(°)
V (Å3)
Z
l
(Mo K
a
) (mmꢁ1
)
0.682
1.490
0.624
1.427
Dcalc (Mg/m3)
1.469
1.459
Crystal size (mm)
h maximum (°)
0.38 ꢂ 0.30 ꢂ 0.21
0.21 ꢂ 0.14 ꢂ 0.11
0.38 ꢂ 0.32 ꢂ 0.24
0.40 ꢂ 0.28 ꢂ 0.22
26.34
30.55
26.37
26.37
Reflections collected
Independent reflections (Rint
Parameters
17744
9058/0.0433
617
1.316
0.0900/0.1736
0.782/ꢁ0.676
6400
6400/0.0481
318
1.106
0.0658/0.1950
1.186/ꢁ0.685
21577
5730/0.0293
385
1.302
0.0546/0.1162
0.600/ꢁ0.365
22766
11449/0.0220
720
1.081
0.0410/0.1031
0.572/ꢁ0.293
)
Goodness-of-fit (GOF) on F2
R1/wR2 (all data)
Residual extrema (e Å3)
3.2. Description of the crystal structures of [Mn(
dmbpy)(NO3)]2 (1), [Mn( -dpp)(Me-phen)(NO3)]2 (2), [Mn(
bmp)(neocuproine)(NO3)]2 (3)
l
-dpp)(5-
MnN2O4 chromophore has a distorted cis-octahedral geometry
mainly derived from the small O–Mn–O# angle of 54.68(13)° and
55.42(13)° (1), 53.77(7)° (2) and 53.93(7)° (3) imposed by the
chelating nitrate ligand. The Mn–N bond lengths are in the range
from 2.217(4) to 2.275(4) Å. The shorter Mn–O(bmp) or Mn–
O(bpp) bonds are in the range from 2.033(4) to 2.0893(19) Å,
whereas the longer Mn–O(nitrate) bonds vary from 2.2056(18) to
2.433(4) Å. By applying inversion symmetry two Mn(II) centers
are pairwise connected by the oxygen atoms of two substituted
l
l-
Partially labeled perspective views of 1–3 are depicted in Figs.
2–4, and relevant bond parameters are given in the Supplementary
Section (Tables S1–S3), respectively. The crystal structures consist
of centrosymmetric dimeric neutral complexes, [Mn(
(5-dmbpy)(NO3)]2 (1), [Mn( -dpp)(Me-phen)(NO3)]2 (2) and
[Mn( -dmp)(neocuproine)(NO3)]2.(MeOH) (3), (Hdpp = diphenyl-
l-dpp)
l
l
phosphinate ligands, thus acting as l
-O,O0-bridges, to form dimeric
phosphinic acid, Hbmp = bis(4-methoxyphenyl)phosphinic acid,
5-dmbpy = 5,50-dimethyl-2,20-dipyridyl, Me-phen = methyl-1,10-
phenanthroline and neocuproine = 2,9-dimethyl-1,10-phenathro-
line). The structure of compound 3 crystallizes with a disordered
MeOH solvent molecule (molar ratio of metal/solvent: 2/1). In com-
pounds 1–3 every Mn(II) center is six-coordinated by two O atoms
units. The core of each dimeric unit consists of an eight-membered
corrugated ring of sequence [Mn–O–P–O#–]2 with intra-ring geo-
metrical parameters summarized in Table 2. The disordered MeOH
solvent molecule of 3 forms a hydrogen bond of type O–H..O to non-
coordinated O atom of nitrate group with O(8)..O(6)[1/2 + x,1/
2 + y,z] distance of 2.722(7) Å. The packing of the dimeric complex
units is further stabilized by ring–ring interactions between
aromatic rings of adjacent dimers.
of a chelating nitrate group, two O atoms of different
l-dpp or
l-dmp bridging anions and two N atoms of a chelate ligand. The
Fig. 2. Perspective view of 1 together with the atom numbering scheme.
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4
F.A. Mautner et al. / Polyhedron xxx (2012) xxx–xxx
four O atoms of two different
-O,O0-bridges [Mn–O: from 2.0068(15) to 2.0318(15) Å; O–Mn–
O: from of 102.02(6)° to 116.78(7)°] to form the polymeric chains
of polyhedra. The core of the [Mn( -bmp)2]n chains consists of
l-bmp anions, thus acting as
l
l
three crystallographic different eight-membered corrugated rings
of sequence [Mn–O–P–O#–]2 with common Mn(II) centers. Two
of them are centrosymmetric with chair conformation, the third
is acentric with distorted boat conformation. Their intra-ring geo-
metrical parameters are summarized in Table 2.
3.4. Infrared spectra
In the three complexes we find several mPO2 absortion bands in
the region 1200–1000 cmꢁ1, wich are diagnostic of bidentate coor-
dination mode of the phosphinate group [22]. Also in all complexes
there is an absortion at ca. 1260 cmꢁ1, very characteristic for
Fig. 3. Perspective view of dinuclear subunit of
numbering scheme.
2 together with the atom
l(P=O) as evidenced in metal phosphates [23]. Complexes 3 and
4
also show the characteristic pattern between 1300 and
500 cmꢁ1 of the bmp ligand [24]. In complexes 1–3 we can also ob-
serve bands at ca. 1450 cmꢁ1 corresponding to the bpy or phen
derivatives and a very strong band at 1384 cmꢁ1 due to the nitrate
group.
3.5. Conformation of the Mn2P2O4 rings
In the present crystal structures of compounds 1–4, seven
eight-membered Mn2P2O4 core rings have been observed with
the following Mn(II) centers: four of them in the dimeric com-
plexes: ring 1A (Mn1..Mn10) and ring 1B (Mn2..Mn200) in 1, ring 2
and ring 3 in complexes 2 and 3, respectively. Three crystallo-
graphic different Mn2P2O4 core units are present in the polymeric
chain of compound 4: ring 4A (Mn1..Mn100), ring 4B (Mn2..Mn20)
and ring 4C (Mn1..Mn2). Only ring 4C is acentric with distorted
boat conformation, the other six are centrosymmetric with dis-
torted chair conformation. Their intra-ring geometrical parameters
are summarized in Table 2.
Fig. 4. Perspective view of 3 together with the atom numbering scheme.
3.3. Description of the crystal structure [Mn(l-bmp)2.1/4H2O]n (4)
The solid state conformational preferences in the [M(l-OPO)]2
core in transition metal complexes double bridged by phosphate
and related ligands (phosphates, phosphonates and phosphinates)
have been extensively studied taking into account that the confor-
mational preferences can play an important role, between others,
in the magnetic or biological properties of the complexes [25,26].
The most probable conformation for each eight-members Mn2P2O4
ring were C2 for compound 1, TC3 for compound 2, and C1 for com-
pound 3. 1–3 show a conformation belonging to the chair family
The structure of complex 4 features a polymeric 1D system,
consisting of [Mn( -bmp)2] subunits, oriented along the x-axis of
the triclinic unit cell and lattice water molecules (molar ratio:
Mn/H2O = 8/1). A partially labeled perspective view of a section
of the polymeric chain of [Mn2(l-bmp)2]n is presented in Fig. 5
l
and relevant bond parameters are given in the Supplementary Sec-
tion (Table S4). Each Mn(II) center is tetrahedrally coordinated by
Table 2
Geometrical parameters of [Mn–O–P–O–]2 eight-membered rings in complexes 1–4.
Ring 1A
Ring 1B
Ring 2
Ring 3
Ring 4A
Ring 4B
Ring 4C
Dist./angle (Å/°)
Mn. . .Mn0
P. . .P0
Mn. . .P
Mn. . .P0
Mn..P..Mn0
P..Mn..P0
O–Mn–O
O–P–O
Mn–O–P
Mn–O–P0
4.776
4.785
3.514
3.241
89.9
5.194
4.693
3.528
3.471
95.8
4.855
5.186
4.462
4.991
3.376
3.319
83.6
4.796
4.863
3.461
3.369
89.2
4.667
4.430
3.400/3.232
3.397/3.355
86.7/90.2
83.8/82.0
114.9/109.1
116.6/117.6
149.3/143.1
149.4/130.9
4.672
3.210
3.521
4.441
3.287
3.537
98.9
81.1
94.7
118.2
130.7
172.7
92.2
90.1
84.2
87.8
101.4
117.8
162.7
126.3
96.4
90.8
107.0
116.8
168.9
129.0
101.1
118.2
163.3
152.5
114.6
116.3
140.0
145.1
112.5
116.0
156.2
144.0
Deviation from mean Plane (Å)
Mn
P
O1
O2
Mean
Mean comp.
Conformat.
0.193
0.004
0.097
0.071
0.074
0.062
0.289
0.143
0.204
0.349
0.246
0.220
0.280
0.004
0.239
0.255
0.195
0.024
0.158
0.146
0.086
0.105
0.195
Chair
0.494/0.339
0.394/0.593
0.158/0.056
0.115/0.140
0.286
0.094
0.138
0.223
0.162
0.112
0.197
0.337
0.098
0.213
0.213
0.246
Twist chair
Chair
Chair
Chair
Chair
Boat
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F.A. Mautner et al. / Polyhedron xxx (2012) xxx–xxx
5
Fig. 5. Perspective view of a section of the polymeric chain of 4 together with the atom numbering scheme.
(chair or twist chair conformation) as the 64% of the data in which
the [M( -OPO)]2 core has not constraints imposed by polycyclic
remain nearly constant and only decreases clearly from approxi-
l
mately T < 25 K indicating antiferromagnetic coupling. The vMT
systems or internal bridges [7]. While in compound 4 two confor-
mations are observed BC1 and C1 where the (boat chair) conforma-
tion is much less known in these systems [9]. The conformations
were established by using the classification method appealing to
RingConf software with sigma = 10° [25].
values at 2 K are 3.21, 7.92 and 7.04 cm3 K molꢁ1 for complexes
1, 2 and 3, respectively. The corresponding vM versus T plots for
1–3 increase on cooling and exhibit no maximum in vM in the tem-
perature range studied. Based on this situation, the experimental
magnetic data have been fitted using the expression derived
ˆ
ˆ ˆ
through the Hamiltonian H = ꢁJSA.SB with SA = SB = 2.5 (Eq. (1)):
vM ¼ ð2Ng2
l
B2=kTÞ½ðexpðJ=kTÞ þ 5expð3J=kT
3.6. Magnetic properties
þ 14expð6J=kTÞ þ 30expð10J=kTÞ þ 55expð15J=kTÞÞ=ð1
þ 3expðJ=kTÞ þ 5expð3J=kTÞ þ 7expð6J=kTÞ
þ 9expð10J=kTÞ þ 11expð15J=kTÞꢃ
Variable-temperature (2–300 K) magnetic susceptibility data
were collected on polycrystalline samples for 1–4. The magnetic
behavior of the manganese(II) compounds 1–4 are represented in
ð1Þ
Figs. 6 and 7 in the form of
vMT versus T plots for 1–3 (Fig. 6)
and of vM versus T plot for 4 (Fig. 7). The structurally related
dinuclear compounds 1–3 show similar behavior with slight
The parameters N, lB and k in Eq. (1) have their usual meanings.
Least-squares fitting of all experimental data leads to the following
parameters: J = ꢁ0.43 cmꢁ1, g = 2.03 for 1, J = ꢁ0.05 cmꢁ1, g = 2.02
for 2 and J = ꢁ0.11 cmꢁ1, g = 2.02 for 3.
differences. At 300 K, the
vMT product are 9.00, 8.90 and
8.90 cm3 K molꢁ1 for complexes 1, 2 and 3, respectively. These val-
ues are slightly higher than the expected for two uncoupled S = 2.5
The coupling constants for 1–3 can be roughly correlated with
the planarity of the dimeric units consisting of the eight-
membered ring of sequence [Mn(1)–O(1)–P(1)–O(2)–]2 the
spins (8.750 cm3 K molꢁ1, g = 2.0). Upon cooling, the
vMT values
Fig. 6. Temperature dependence of
v
MT of a solid sample of compounds 1–3. The
Fig. 7. Temperature dependence of vM of a solid sample of complex 4. The solid
solid lines represent the best fit (see text).
lines represent the best fit (see text).
Please cite this article in press as: F.A. Mautner et al., Polyhedron (2012), http://dx.doi.org/10.1016/j.poly.2012.07.028

6
F.A. Mautner et al. / Polyhedron xxx (2012) xxx–xxx
Table 3
anions, showing a not usual chain of Mn(II)O4 tetrahedra. 4 shows
also antiferromagnetic coupling with a J value of ꢁ0.88 cmꢁ1
.
Values of the arithmetic mean value of the absolute deviations for the mean planes of
the eight-membered rings of sequence [Mn(1)–O(1)–P(1)–O(2)–]2 and calculated |J|
values.
Acknowledgments
Compound
Mean value (Å)
|J|, cmꢁ1
Ref.
[Mn(
[Mn(
[Mn2(
1
2
3
l
l
l
-bmp)(bpy)(NO3)]2
-bmp)(phen)(NO3)]2
-bmp)2(5-dmbpy)2(NO3)]2
0.227
0.256
0.055
0.112
0.246
0.213
0.41
0.11
0.61
0.43
0.05
0.11
[8]
[8]
[8]
This work
This work
This work
This research was supported by the Spanish MEC (Grant
CTQ2009-07264) and the Generalitat de Catalunya (Grant
2009SGR1454). F.A.M. thanks Dr. Baumgartner (TU-Graz) for
experimental assistance.
Appendix A. Supplementary data
CCDC-881355 to CCDC-881358 contain the supplementary
crystallographic data for this paper. These data can be obtained
free of charge via http://www.ccdc.cam.ac.uk/conts/retriev-
ing.html, or from the Cambridge Crystallographic Data Centre, 12
Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033;
or email: deposit@ccdc.cam.ac.uk. Supplementary data associated
with this article can be found, in the online version, at http://
dx.doi.org/10.1016/j.poly.2012.07.028.
arithmetic mean value of the absolute deviations for the three
mean planes are 0.112, 0.246 and 0.213 for 1, 2 and 3, respectively
and the |J| values are 0.43, 0.05 and 0.11 cmꢁ1, respectively. More
planar, higher |J| value. The same result has been observed in
[10]. In Table 3 are reported the values of the arithmetic mean va-
lue of the absolute deviations for the three mean planes with the |J|
values for the compounds 1–3 and the previously reported similar
compounds [10].
The 1D compound 4 has a different behavior: at 300 K, the
product is 4.44 cm3 K molꢁ1. This value is slightly higher than the
expected for one uncoupled S = 2.5 spin (4.375 cm3 K molꢁ1
g = 2.0). Upon cooling, the MT values remain nearly constant
vMT
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4. Conclusion
A series of three dinuclear complexes of composition, [Mn(
dpp)(5-dmbpy)(NO3)]2 (1), [Mn( -dpp)(Me-phen)(NO3)]2 (2) and
[Mn( -dmp)(neocuproine)(NO3)]2.(MeOH) (3), (Hdpp = diphenyl-
l-
l
l
phosphinic acid, Hbmp = bis(4-methoxyphenyl)phosphinic acid,
5-dmbpy = 5,50-dimethyl-2,20-dipyridyl, Me-phen = methyl-1,10-
phenanthroline and neocuproine = 2,9-dimethyl-1,10-phenathro-
line have been synthesized and structurally characterized. The cen-
trosymmetric neutral dimers feature common octahedral Mn(II)
centers, chelating nitrate groups, chelating chelate ligands L, and
l
-O,O0-bridging substituted phosphinato anions. 1–3 are slightly
antiferromagnetically coupled according with the described
observation that the
-O,O0 O–P–O bridges give rise to negligible
l
exchange interactions.[17,18] The coupling constants can be
roughly correlated with the planarity of the dimeric units consist-
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O(2)–]2: the arithmetic mean value of the absolute deviations for
the three mean planes are 0.112, 0.246 and 0.213 for 1, 2 and 3
respectively and the |J| values are 0.43, 0.05 and 0.11 cmꢁ1 respec-
tively. More planar, higher |J| value. We have also synthesized the
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1D compound of formula [Mn(
l-bmp)2]n (4) which is built from
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Please cite this article in press as: F.A. Mautner et al., Polyhedron (2012), http://dx.doi.org/10.1016/j.poly.2012.07.028