Unprecedented calcium metalla-macrocycle having phosphinoselenoic amide and diphenylphosphinate in the coordination sphere

Article abstract of DOI:10.1002/zaac.201300492

An eight-membered calcium metalla-macrocycle of the composition [Ca{Ph ₂P(Se)N(Ar)}{Ph₂P(O)O}(THF)₂]₂ (2) (Ar = 2, 6-dimethylphenyl) can be isolated with a good yield by the reaction of neutral phosphinoselenoic amide [Ph₂P(Se)NH(Ar)] (1) and calcium bis(trimethylsilyl)amides [Ca{N(SiMe₃)₂} ₂(THF)₂] in toluene followed by crystallization in air. The homoleptic calcium phosphinoselenoic amido complex of the composition [Ca{Ph₂P(Se)N(Ar)}₂(THF)₂] (3) can also be obtained through two synthetic routes. In the first route, [Ca{N(SiMe ₃)₂}₂(THF)₂] is treated with phosphinoselenoic amide [Ph₂P(Se)NH(Ar)] (1) at an ambient temperature followed by re-crystallization in an inert atmosphere to give complex 3 of high purity. In the second route, a one-pot reaction is carried out involving 1, calcium diiodide, CaI₂, and potassium bis(trimethylsilyl)amide [K{N(SiMe₃)₂}] in toluene in an inert atmosphere. When complex 3 is treated with diphenylphosphinic acid in THF, compound 2 is also obtained with a good yield. Both complexes are confirmed using single-crystal X-ray diffraction analysis. The solid-state structure of complex 2 reveals an eight-membered macrocycle formed by two diphenylphosphinate groups and two calcium ions. In addition, a four-membered calcium metallacycle around each calcium atom is formed by the phosphinoselenoic amido ligand through coordination between the nitrogen and selenium atoms. In complex 3, the calcium atom is coordinated by two phosphinoselenoic amido groups and a direct metal selenium bond is observed. Copyright

Full text of DOI:10.1002/zaac.201300492

ARTICLE
DOI: 10.1002/zaac.201300492
Unprecedented Calcium Metalla-macrocycle Having Phosphinoselenoic
Amide and Diphenylphosphinate in the Coordination Sphere
Kishor Naktode,[a] Jayeeta Bhattacharjee,[a] Sayak Das Gupta,[a] Hari Pada Nayek,[b]
Bhabani S. Mallik,[a] and Tarun K. Panda*[a]
Keywords: Macrocycle; Calcium; Selenium; Chelating ligand; N,Se donor
Abstract. An eight-membered calcium metalla-macrocycle of the ing 1, calcium diiodide,CaI2, and potassium bis(trimethylsilyl)amide
composition [Ca{Ph2P(Se)N(Ar)}{Ph2P(O)O}(THF)2]2 (2) (Ar = 2,6- [K{N(SiMe3)2}] in toluene in an inert atmosphere. When complex 3
dimethylphenyl) can be isolated with a good yield by the reaction of
neutral phosphinoselenoic amide [Ph2P(Se)NH(Ar)] (1) and calcium obtained with a good yield. Both complexes are confirmed using sin-
bis(trimethylsilyl)amides [Ca{N(SiMe3)2}2(THF)2] in toluene fol- gle-crystal X-ray diffraction analysis. The solid-state structure of com-
lowed by crystallization in air. The homoleptic calcium phosphinosele- plex 2 reveals an eight-membered macrocycle formed by two di-
is treated with diphenylphosphinic acid in THF, compound 2 is also
noic amido complex of the composition [Ca{Ph2P(Se)N(Ar)}2(THF)2]
(3) can also be obtained through two synthetic routes. In the first route,
phenylphosphinate groups and two calcium ions. In addition, a four-
membered calcium metallacycle around each calcium atom is formed
[Ca{N(SiMe3)2}2(THF)2] is treated with phosphinoselenoic amide by the phosphinoselenoic amido ligand through coordination between
[Ph2P(Se)NH(Ar)] (1) at an ambient temperature followed by re- the nitrogen and selenium atoms. In complex 3, the calcium atom is
crystallization in an inert atmosphere to give complex 3 of high
coordinated by two phosphinoselenoic amido groups and a direct metal
purity. In the second route, a one-pot reaction is carried out involv- selenium bond is observed.
additional donating atoms in the periphery have achieved
Introduction
greater importance in catalysis and in the design of self-as-
sembling ligands.[9] Recently, Stalke et al. demonstrated vari-
ous phosphorus-based ligands with the incorporation of het-
eroaromatic substituents at the phosphorus atom to lead the
design of multidentate Janus-head ligands.[10,11] These ligand
systems with sidearm donation have already proved to be use-
ful in various catalytic reactions involving chelating phospha-
nes with selectivity for hard/soft coordination sites.[12]
Our work focuses on the exploration of synthetic methodol-
ogies allowing for a facile, clean, high-yield production of the
required molecules and determination of the molecular struc-
ture and function. In our ongoing project we have synthesized
Determining the structure and reactivity of alkaline earth
metal species is an important step towards the design and de-
velopment of efficient catalysts; however, full realization of
the catalytic potential of these elements requires substantial
advances in understanding their basic coordination and organo-
metallic chemistry.[1] To stabilize these extremely oxophilic
and electropositive metals, a wide variety of nitrogen-based
ancillary ligands, such as tris(pyrazolyl)borates,[2] aminotro-
poniminates,[3] β-diketiminates,[4] iminopyrroles,[5] and 1,4-di-
aza-1,3-butadiene[6] have been introduced to prepare well-de-
fined alkaline earth metal complexes, revealing that the cata-
lytic activity and selectivity of the alkaline earth metal com-
N-(diphenylphosphanyl)-2,6-dimethylaniline
[Ph2PNH(2,6-
Me2C6H3)] and its chalcogenides [Ph2P(O)NH(2,6-Me2C6H3)]
plexes can be controlled through well-defined nitrogen-based and [Ph2P(S)NH(2,6-Me2C6H3)][13] and their complexes with
alkali metals. Recently we reported a number of alkali metal
polycyclic compounds using various phosphinamine chalco-
genide ligands.[14] Further, we have introduced the new bulky
seleno-phosphinamines [Ph2P(Se)NH(CHPh2)] and [Ph2P(Se)
NH(CPh3)] derived from the bulky phosphinamines
[Ph2PNH(CHPh2)] and [Ph2PNH(CPh3)] with elemental selen-
ium, having (Se, P, N)-chelating coordination sites, into alka-
line earth metal chemistry. These unique ligands are potentially
capable of coordinating through the hard nitrogen and phos-
phorus donor atoms along with the soft selenium donor atom.
The heavier alkaline earth metal complexes [M(THF)2-
{Ph2P(Se)-N(CHPh2)}2] (M = Ca, Sr, Ba) that we reported
show four-membered metallacycles with calcium and its
higher congeners.[15]
ligand architecture. Various phosphine imines and phosphine
amines have been used for the design of new alkaline earth
metal compounds having well-defined reaction centers.[7,8]
More recently, the concept of phosphorus-based ligands with
* Dr. T. K. Panda
Fax: + 91-40-23016032
E-Mail: tpanda@iith.ac.in
[a] Department of Chemistry
Indian Institute of Technology Hyderabad
Ordnance Factory Estate
Yeddumailaram 502205, Andhra Pradesh, India
[b] Department of Applied Chemistry
Indian School of Mines
Dhanbad, 826004, Jharkhand, India
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Z. Anorg. Allg. Chem. 2014, 640, (5), 994–999

Phosphinoselenoic Amide and Diphenylphosphinate in Coordination Sphere of Calcium Metalla-macrocycle
Herein we report the syntheses and-solid-state structures of complexes 2 and 3, respectively. Eight ortho-protons of the
eight-membered calcium metalla-macrocycle of the composi- four phenyl rings attached to diphenylphosphinates were
tion [Ca{Ph2P(Se)N(Ar)}{Ph2P(O)O}(THF)2]2 (2) along with highly deshielded and appeared at δ = 8.30 ppm as a broad
the homoleptic calcium phosphinoselenoic amido complex of singlet signal for compound 2, whereas a multiplet signal at δ
the composition [M{Ph2P(Se)N(Ar)}2(THF)2] (3).
= 7.98–7.92 ppm and a broad singlet at δ = 6.90 ppm were
observed in other phenyl protons for complex 2. In both com-
plexes, the broad peaks at δ = 3.42 and 1.14 ppm corresponded
to the coordinated four THF molecules attached to two calcium
atoms for complex 2 and two THF molecules for complex 3,
which were confirmed by the solid-state structures (vide infra).
In proton decoupled 31P spectra, complex 2 showed two
equally intense peaks at δ = 64.7 ppm and 42.6 ppm whereas
compound 3 showed only a singlet at δ = 65.7 ppm. The singlet
at δ = 64.7 ppm (for 2) and 65.6 ppm (for 3) can be assigned
to the diphenylphosphinoselenoic amido group present in both
complexes. The signal at δ = 42.6 ppm for complex 2 therefore
can be assigned to the phosphorus atom, which is highly shi-
elded due to the greater number of electronegative oxygen
atoms present adjacent to it in bridging diphenylphosphinate
groups. In addition, for compound 3, two satellite peaks on
either side of the signal at δ = 65.7 ppm were also observed
due to the coupling of 31P and the less abundant (7.6 per cent)
77Se, for both nuclei having a nuclear spin I = ½.
Results and Discussion
The complex [Ca{Ph2P(Se)N(Ar)}{Ph2P(O)O}(THF)2]2 (2)
(Ar = 2,6-dimethylphenyl) was isolated, with a good yield,
when phosphinoselenoic amide [Ph2P(Se)NH(Ar)] (1) was
made to react with calcium bis(trimethylsilyl)amides [Ca{N-
(SiMe3)2}2(THF)2] in toluene followed by crystallization in
hydrous condition in air (see Scheme 1). However, when the
reaction mixture was subjected to crystallization in an inert
atmosphere, calcium complex 3 was isolated, with a good
yield. Complex 3 can also be prepared by a one-pot reaction
involving ligand 1, calcium diiodide, and potassium bis(trime-
thylsilyl)amide in THF at an ambient temperature in an inert
atmosphere (see Scheme 2). Complex 2 can also be obtained
by the treatment of complex 3 and diphenyl phosphinic acid
in an inert atmosphere (see Scheme 1). Both compounds 2 and
3 were characterized by standard combustion analysis as well
as spectroscopic techniques. The solid-state structures of com-
plexes 2 and 3 were established by single-crystal X-ray diffrac-
tion analysis.
The solid-state structures of compounds 2 and 3 were con-
firmed by single-crystal X-ray diffraction analysis. The data
collection parameters are set out in Table 1. The centrosym-
metric compound 2 was crystallized in a monoclinic space
group P21/c having two molecules in the unit cell along with
one toluene molecule as the solvent, whereas compound 3 was
Table 1. Crystallographic details of [Ca{Ph2P(Se)N(Ar)}{Ph2P(O)
O}(THF)2]2 (2) and [Ca(THF)2{Ph2P(Se)N(Ar)}2] (3).
2·2toluene
3
Formula
C94H106Ca2N2O8
P4Se2
C48H54CaN2O2
P2Se2
Formula weight
Crystal system
Space group
1753.77
monoclinic
P21/c
950.87
orthorhombic
Pbca
Scheme 1. Synthesis of complex 2.
a /Å
b /Å
c /Å
α /°
18.2918(4)
17.1014(3)
5.1820(3)
90
17.7165(4)
17.2738(4)
29.6492(12)
90
β /°
94.399(2)
90
4735.17(16)
2
1.230
150(2)
90
90
9073.6(5)
8
1.392
γ /°
V /Å3
Z
Density /mg·m–3
T /K
150(2)
Radiation
Cu-Kα (λ =
1.54184 Å)
2.974
Cu-Kα (λ =
1.54184 Å)
4.000
3920
multi-scan
25968
8600 [Rint = 0.0379]
98.4%
1.032
Full-matrix least-
squares on F2
0.0456; 0.0943
Scheme 2. Synthesis of complex 3.
μ /mm–1
F(000)
The FT-IR spectra of compounds 2 and 3 showed strong
absorption bands for P=Se bond stretching at 568 cm–1 and
569 cm–1 respectively. These values are well in agreement with
previously observed P=Se stretching frequencies.[13] When the
1H NMR spectra of compounds 2 and 3 were recorded in
C6D6, one set of signals was observed in each case. A sharp
singlet at δ = 1.99 and 2.05 ppm can be assigned to the 12
methyl protons attached in the 2,6-dimethylphenyl moieties of
1832
Absorption correction multi-scan
Reflections collected 19659
Unique reflections
Completeness to θ
GOF
8798 [Rint = 0.0363]
97.0%
1.042
Full-matrix least-
squares on F2
0.0893; 0.2188
Refinement method
R1; wR2
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995

T. K. Panda et al.
ARTICLE
crystallized in an orthorhombic space group Pbca with eight 2.479(5) Å observed for [Ca(THF)2{Ph2P(Se)N(CHPh2)}2], as
molecules in the unit cell.
we reported.[15] The Ca–P distance 3.287 Å for compound 2 is
Figure 1 shows the solid-state structure of compound 2 along significantly larger than the sum of the covalent radii (3.07 Å)
with the macrocyclic ring of molecule 2; the molecular structure of phosphorus and calcium, indicating no interaction between
of compound 3 is given in Figure 2. Compound 2 is a dimer of these two atoms. The Ca1–O3 [2.470(3) Å] bond [2.372(3) Å]
the asymmetric unit [Ca{Ph2P(Se)N(Ar)}{Ph2P(O)O}(THF)2], is slightly elongated when compared to the Ca1–O4 bond, pre-
where each calcium polyhedron is formed by the chelation of sumably due to greater electron release by diphenylphosphi-
bidentate mono-anionic diphenylphosphinoselenoic amido nate oxygen trans to Ca1–O3 bond. An eight-membered
moiety and diphenylphosphinate [PhP2P(O)O] along with two metalla-macrocycle Ca1–O1–P1–O2–Ca1i–O1i–P1i–O2i is
THF molecules. In {Ph2P(Se)N(Ar)}– moiety, nitrogen and formed by the chelation of two diphenylphosphinate groups
selenium atoms coordinate with the calcium atom and two and two calcium ions. The conformation of the eight-mem-
oxygen atoms in the [PhP2P(O)O] group act as bridging li- bered ring can be best described as chair shaped (see Figure 1,
gands, coordinating with the two calcium atoms. Thus, each bottom), with a dihedral angle of 20.30° between the average
calcium metal is coordinated six fold, and adopts a distorted planes containing Ca1 O1 Ca1i Ca1 O1i and Ca1, O2, P1i,
arrangement around it. Two four-member metallacycles, Ca1– and O1i atoms. The distance between the two opposite calcium
N1–P2–Se1 and Ca1i–N1i–P2i–Se1i, are formed by the coordi- atoms is 5.400 Å. To the best of our knowledge this is the first
nation of two {Ph2P(Se)N(Ar)}– moieties and two calcium example of an eight-membered calcium metalla-macrocycle.
ions. The bond lengths, Ca1–Se1 [3.0337(9) Å] and Ca1–N1 P1–O1 and P1–O2 bond lengths [1.499(3) Å and 1.504(3) Å,
[2.452(4) Å], are similar in range to the 2.9889(8) Å and respectively] are equal due to the delocalization of the negative
charge over two oxygen atoms attached to the phosphorus
atom in the diphenylphosphinate group.
Figure 2. Solid-state structure of compound 3 showing the atom label-
ling scheme. Hydrogen atoms are omitted for clarity. Selected bond
lengths /Å and bond angles /° for 3: Ca1–N1 2.398(2), Ca1–N2
2.435(2), Ca1–Se1 3.0259(6), Ca1–Se2 3.0418(6), Ca1–P1 3.2819(8),
Ca1–P2 3.2984(8), Se1–P1 2.1461(7), Se2–P2 2.1455(7), P1–N1
1.612(2), P2–N2 1.611(2), Ca1–O1 2.3905(19), Ca1–O2 2.424(2), O1–
Ca1–N1 85.99(7), O1–Ca1–O2 90.64(7), N1–Ca1–O2 105.62(7), O1–
Ca1–N2 95.78(7), N1–Ca1–N2 162.43(7), O2–Ca1–N2 91.86(7), N1–
Figure 1. Solid-state structure of compound 2 showing the atom-label-
ling scheme (top) and macro cyclic ring of compound 2 (bottom).
Hydrogen atoms are omitted for clarity. Selected bond lengths /Å and
bond angles /° for 2: Ca1–Se1 3.0337(9), Ca1–N1 2.452(4), Ca1–P2
Ca1–Se1 67.28(5), N2–Ca1–Se1 112.93(5), N1–Ca1–Se2 95.95(5),
3.2872(13), Ca1–O1 2.242(3), Ca1–O2 2.257(3), Ca1–O4 2.372(3),
N2–Ca1–Se2 66.49(5), Se1–Ca1–Se2 94.685(16), N1–Ca1–P1
Ca1–O3 2.470(3), Ca1–P1i 3.5536(13), N1–P2 1.610(4), O1–P1
27.79(5).
1.499(3), O2-P1i 1.504(3), P1-O2i 1.504(3), P1-Ca1i 3.5536(13), P2–
Se1 2.1513(11), O1–Ca1–O2 97.64(10), O1–Ca1–N1 103.67(11), O2–
Ca1–N1 104.53(12), O4–Ca1–N1 159.12(12), N1–Ca1–O3 91.99(12),
In molecule 3, the coordination polyhedron is formed by the
chelation of two mono-anionic {Ph2P(Se)N(Ar)}– ligands, and
two THF molecules. Each {Ph2P(Se)N(Ar)}– ligand coordi-
nates with the calcium atom through chelation of one amido
nitrogen and one selenium atom. The P–Ca distances of
3.2819(8) Å and 3.2984(8) Å are significantly greater than the
O1–Ca1–Se1 90.71(8), O2–Ca1–Se1 169.58(8), N1–Ca1–Se1
67.22(9), O3–Ca1–Se1 87.48(8), O1–Ca1–P2 103.43(8), O2–Ca1–P2
131.43(8), N1–Ca1–P2 28.06(9), Se1–Ca1–P2 39.54(2), O1–Ca1–P1i
82.83(8), N1–Ca1–P1i 112.58(10), O3–Ca1–P1i 99.20(8), Se1–Ca1–
P1i 173.32(3), P2–Ca1–P1i 140.64(3), P2–N1–Ca1 106.18(19), P1–
O1–Ca1 161.71(18), P1i–O2–Ca1 140.91(16), O1–Ca1–O2 97.64(10),
O1–Ca1–O4 85.92(11), O1–Ca1–N1 103.67(11).
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Phosphinoselenoic Amide and Diphenylphosphinate in Coordination Sphere of Calcium Metalla-macrocycle
sum of the covalent radii (3.07 Å) of phosphorus and calcium,
indicating no interaction between these two atoms. However,
P–Ca bond lengths are similar in range (3.287 Å) to those of
compound
2 (3.274 Å) and for [Ca(THF)2{Ph2P(Se)N-
(CHPh2)}2], as we reported.[15] Thus, the {Ph2P(Se)N(Ar)}–
group acts as bidentate ligand and the arrangement around the
calcium atom can be best described as a distorted octahedral
due to coordination between the two {Ph2P(Se)N(CHPh2)}–
moieties and two THF molecules. Two four-membered cal-
cium metallacycles, Ca1–N1–P1–Se1 and Ca1–N2–P2–Se2,
are formed. The Ca–N distances [2.398(2) Å and 2.435(2) Å]
are similar in range [2.452(4) Å] to those of complex 2, but are
slightly elongated compared with calcium–nitrogen distances
[2.361(2) Å and 2.335(2) Å] reported for [Ca(Dipp2DAD)-
(THF)4] [Dipp2DAD = N,NЈ-bis(2,6-diisopropylphenyl)-1,4-
diaza-1,3-butadiene] in literature.[6a] The most interesting fea-
ture is that the Ca–Se bond lengths [3.0259(6) Å and
3.0418(6) Å] are similar in range with those of complex 2
Figure 3. ORTEP drawing of the calculated structure 2a. Selected
bond lengths /Å and bond angles /°, for comparison, experimental val-
ues are given in parentheses: Ca1–Se11 3.116 [3.0337], Ca1–N1 2.474
[2.452], Ca1–P2 3.340 [3.2872], Ca1–O1 2.273 [2.242], Ca1–O2 2.272
[2.257], Ca1–P3 3.685 [3.5536], N1–P2 1.597[1.610], O1–P1
1.510[1.499], O2–P3 1.512[1.504], P1–O3 1.510[1.504], P1–Ca2
3.685 [3.5536], P2–Se1 2.148 [2.1513], O1–Ca1–O2 101.34 [97.64],
P1–O1–Ca1 160.58 [161.71], P3–O2–Ca1 153.26 [140.91].
[3.0337(9) Å]
and
[Ca(THF)2-{Ph2P(Se)N(CHPh2)}2]
[2.989(8) Å] as we reported. Ca–Se bond lengths observed in
complexes 2 and 3 also match with the reported Ca–Se values
with 2.945(1) Å for [(THF)2Ca{(PyCH)(Se)PPh2}2][16] and
2.9336(4) Å for [(THF)4Ca(SeMes’)2][17] in literature. Thus,
complexes 2 and 3 are examples of compounds with direct
calcium–selenium bond.[15–17] The P–Se distance in complexes
2 and 3 [2.1513(11) Å and 2.1461(7) Å, respectively] is in the
same range as that of [Ca(THF)2{Ph2P(Se)N(CHPh2)}2]
[2.1449(2) Å], indicating similar coordination of diphenyl-
phosphinoselenoic amido group with the calcium atom. It is
noteworthy that the two nitrogen atoms and two selenium
atoms of the {Ph2P(Se)N(Ar)}– group are chelated to calcium
in cis fashion along with two cis THF molecules. However,
the reverse phenomenon, that is nitrogen, selenium, and oxy-
gen atoms being trans in the analogous compound [Ca(THF)2-
{Ph2P(Se)N(CHPh2)}2], was observed.
Conclusions
We have reported the syntheses and solid-state structures of
an eight-membered calcium metalla-macrocycle along with the
homoleptic calcium phosphinoselenoic amido complex. The
eight-membered ring is formed by the coordination of two di-
phenylphosphinate groups and two calcium atoms, and each
calcium ion is again coordinated with one mono-anionic di-
phenylphosphinoselenoic amido group and two THF mole-
cules to satisfy the sixfold coordination for each calcium atom.
Both complexes also contain the direct calcium–selenium
bond.
Experimental Section
Theoretical Investigation of the Bonding in Compound 2
All manipulations involving air- and moisture-sensitive organometallic
compounds were carried out in an argon atmosphere using the standard
Schlenk technique or argon-filled glove box. Hydrocarbon solvents (n-
pentane, toluene) were distilled in nitrogen from LiAlH4 and stored in
the glove box. THF was dried and deoxygenated by distillation over
sodium benzophenone ketyl in an argon atmosphere and additionally
distilled and dried with CaH2 prior to storing in the glove box.
[D6]Benzene was dried with Na/K alloy and stored in the glove box.
1H NMR (400 MHz), 13C NMR (100 MHz), and 31P (161.9 MHz)
spectra were measured with a Bruker Avance III-400 spectrometer.
Elemental analyses were performed with a Bruker Euro EA at the
To confirm the experimentally obtained bonding features of
the eight-membered calcium metalla-macrocyclic compound 2,
we performed ab initio calculations (HF/3-21G*) on the iso-
electronic model calcium complex 2a, where bulky phenyl
groups are substituted by methyl groups to achieve higher
symmetry.[18] The structure of complex 2a was freely opti-
mized with no geometric constraint and the calculated geome-
tries (see Figure 3) were found to be in good agreement with
those established by X-ray diffraction. In complex 2a, the cal- Indian Institute of Technology, Hyderabad. Diphenylphosphinosele-
noic amide [Ph2P(Se)NH(Ar)] (1)[13] and calcium bis(trimethylsilyl)
culated Ca1–N1 distance of 2.474 Å matched perfectly with
the Ca–N1 bond length (2.452 Å), which was experimentally
determined for molecules of complex 2. The calculated Ca1–
amides [Ca{N-(SiMe3)2}2(THF)2][19] were prepared according to pro-
cedures prescribed in the literature.
O1 (2.273 Å) and Ca1–O2 (2.272 Å) lengths also matched the
[Ca{Ph2P(Se)N(Ar)}{Ph2P(O)O}(THF)2]2 (2): In
a dry 25 mL
experimental values (2.242 Å and 2.257 Å, respectively). The
theoretical bond angles of complex 2a O1–Ca1–O2 (101.34°),
P1–O1–Ca1 (160.58°) were also in good agreement with ex-
perimentally determined values (97.64° and 161.71°).
Schlenk tube, the ligand 1 (100 mg, 0.26 mmol) and calcium bis(trime-
thylsilyl)amide (66 mg, 0.13 mmol) were placed together and toluene
(5 mL) was added to it. The reaction mixture was stirred at an ambient
temperature for 20 h. The solvent was evaporated to half of its volume
Z. Anorg. Allg. Chem. 2014, 994–999
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997

T. K. Panda et al.
ARTICLE
and THF (1 mL) was layered on to it. The entire solution was kept
outside under controlled air. Colorless crystals were obtained after 3
d. Yield 70 mg (68%). H NMR (400 MHz, C6D6, 25 °C): δ = 8.30
sion, India for their PhD fellowship. Generous support from K. Mash-
ima, Osaka University, Japan is also gratefully acknowledged.
1
(br., 8 H, ArH), 7.96–7.92 (m, 8 H, ArH), 6.90 (br., 24 H, ArH), 6.88
(br., 6 H, ArH), 3.47 (br., 8 H, THF), 1.99 (s, 12 H, CH3), 1.14 (br.,
8 H, THF). 31P{1H} NMR (161.9 MHz, C6D6): δ = 64.7 (P=Se) and
42.6 (P=O) ppm. FT-IR (selected frequencies): ν˜ = 1359 (P–C), 1199
(P=O), 924 (P–N), 568 (P=Se) cm–1. C94H106Ca2 N2O8P4Se2
(2·2toluene, 1753.83): calcd. C 61.22, H 5.78, N 1.78%; found, C
60.91, H 5.63, N 1.52%.
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[Ca(THF)2{Ph2P(Se)N(Ar)}2] (3): Route 1: Same as above. The
recrystallization was accomplished in an inert atmosphere at –35 °C.
Colorless crystals were obtained. Yield 65%.
Route 2: A mixture of the ligand 1 (100 mg, 0.26 mmol), potassium
bis(trimethylsilyl)amide (52 mg, 0.26 mmol) and calcium iodide
(38 mg, 0.13 mmol) was charged with dry THF (5 mL) and the reac-
tion mixture was stirred for 12 h. The white precipitate of KI was
filtered to leave behind a colorless filtrate. The filtrate was evaporated
to half of its volume and pentane (3 mL) was layered on to it. Colorless
crystals of 3 were obtained at –35 °C. Yield 81 mg, 65%. 1H NMR
(400 MHz, C6D6, 25 °C): δ = 7.98–7.92 (m, 8 H, ArH), 7.01–6.98 (m,
12 H, ArH), 6.89 (br., 6 H ArH), 3.47 (br., 8 H, THF), 2.05 (s, 12 H,
CH3), 1.14 (br., 8 H, THF). 31P{1H} NMR (161.9 MHz, C6D6): δ =
65.7 (P=Se) ppm. FT-IR (selected frequencies): ν˜ = 1357 (P–C), 920
(P–N), 569 (P=Se) cm–1. C48H54CaN2O2P2Se2 (950.90): calcd. C
60.63, H 5.72, N 2.95%; found, C 60.24, H 5.43, N 2.69%.
X-ray Crystallographic Analyses: Single crystals of complex 2 were
obtained from a solution of THF/pentane (1:2) under hydrous condi-
tion, whereas single crystals of complex 3 were obtained in an argon
atmosphere at a temperature of –35 °C. In each case, a crystal of suit-
able dimensions was mounted on a CryoLoop (Hampton Research
Corp.) with a layer of light mineral oil and placed in a nitrogen stream
at 150(2) K. All measurements were made with an Oxford Supernova
X-calibur Eos CCD detector with graphite-monochromatic Cu-Kα
(1.54184 Å) radiation. Crystal data and structure refinement param-
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isotropically refined. Hydrogen atoms were included in the refinement
on calculated positions riding on their carrier atoms. The function
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2
2 2
2
minimized was [Σw(Fo – Fc ) ] (w = 1 / [σ2 (Fo ) + (aP)2 + bP]),
2
2
where P = (Max(Fo2,0) + 2Fc ) / 3 with σ2(Fo ) from counting statis-
2
tics. The function R1 and wR2 were (Σ||Fo| – |Fc||) / Σ|Fo| and [Σw(Fo
Fc ) / Σ(wFo )]1/2, respectively. The ORTEP-3 program[22] was used
–
2 2
4
to draw the molecule.
Crystallographic data (excluding structure factors) for the structures in
this paper have been deposited with the Cambridge Crystallographic
Data Centre, CCDC, 12 Union Road, Cambridge CB21EZ, UK. Copies
of the data can be obtained free of charge on quoting the depository
numbers CCDC-960672 (2) and CCDC-960673 (3) (Fax: +44-1223-
336-033; E-Mail: deposit@ccdc.cam.ac.uk, http://www.ccdc.cam.
ac.uk).
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Acknowledgements
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This work was supported by the Council of Scientific and Industrial
Research (CSIR) Scheme (No. 01(2530)/11/EMRII) and start-up grant
from IIT Hyderabad. KN and JB thank the University Grants Commis-
998
www.zaac.wiley-vch.de
© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2014, 994–999

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Received: September 27, 2013
Published Online: December 3, 2013
Z. Anorg. Allg. Chem. 2014, 994–999
© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
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