Resorcinol based acyclic dimeric and cyclic di- and tetrameric cyclodiphosphazanes: Synthesis, structural studies, and transition metal complexes

Article abstract of DOI:10.1021/ic300541n

The condensation reaction of resorcinol with cis-[ClP(μ-N ^tBu)₂PN(H)^tBu] produced a difunctional derivative 1,3-C₆H₄[OP(μ-N^tBu) ₂PN(H)^tBu]₂ (1), whereas the similar reaction with [ClP(μ-N^tBu)]₂ resulted in the formation of a 1:1 mixture of dimeric and tetrameric species, [{P(μ-N^tBu)} ₂{1,3-(O)₂-C₆H₄}]₂ (2a) and [{P(μ-N^tBu)}₂{1,3-(O)₂-C ₆H₄}]₄ (2b), which were separated by repeated fractional crystallization and column chromatography. The reaction of dimer 2a with H₂O₂ and selenium produces tetrachalcogenides [{(O)P(μ-N^tBu)}₂{1,3-(O)₂-C ₆H₄}]₂ (3) and [{(Se)P(μ-N ^tBu)}₂{1,3-(O)₂-C₆H ₄}]₂ (4), respectively. The reaction between the dimer (2a) and [Pd(μ-Cl)(·³-C₃H₅)] ₂ or AuCl(SMe₂) yielded the corresponding tetranuclear complexes, [{((Cl)(·³-C₃H₅)Pd)P(μ- N^tBu)}₂{1,3-(O)₂-C₆H ₄}]₂ (5) and [{(ClAu)P(μ-N^tBu)} ₂{1,3-(O)₂-C₆H₄}]₂ (6) in good yield. The complexes 5 and 6 are the rare examples of phosphorus macrocycles containing two or more exocyclic transition metal fragments. Treatment of 1 with copper halides in 1:1 molar ratio resulted in the formation of one-dimensional (1D) coordination polymers, [(CuX){1,3-C₆H ₄{OP(μ-N^tBu)₂PN(H)^tBu}} ₂]_n (7, X = Cl; 8, X = Br; 9, X = I), which showed the helical structure in solid state because of intramolecular hydrogen bonding, whereas similar reactions of 1 with 4 equiv of copper halides also produced 1D-coordination polymers, [(Cu₂X₂)₂{1,3-C ₆H₄{OP(μ-N^tBu)₂PN(H) ^tBu}₂}]_n (10, X = Cl; 11, X = Br; 12, X = I), but containing Cu₂X₂ rhomboids instead of CuX linkers. The crystal structures of 1, 2a, 2b, 4, 7-9, and 12 were established by X-ray diffraction studies.

Full text of DOI:10.1021/ic300541n

Article
pubs.acs.org/IC
Resorcinol Based Acyclic Dimeric and Cyclic Di- and Tetrameric
Cyclodiphosphazanes: Synthesis, Structural Studies, and Transition
Metal Complexes
Guddekoppa S. Ananthnag,† Seema Kuntavalli,† Joel T. Mague,‡ and Maravanji S. Balakrishna*,†
†Phosphorus Laboratory, Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India
‡Department of Chemistry, Tulane University, New Orleans, Louisiana 70118, United States
S
* Supporting Information
ABSTRACT: The condensation reaction of resorcinol with
cis-[ClP(μ-NtBu)2PN(H)tBu] produced a difunctional deriva-
tive 1,3-C6H4[OP(μ-NtBu)2PN(H)tBu]2 (1), whereas the
similar reaction with [ClP(μ-NtBu)]2 resulted in the formation
of a 1:1 mixture of dimeric and tetrameric species, [{P(μ-
NtBu)}2{1,3-(O)2-C6H4}]2 (2a) and [{P(μ-NtBu)}2{1,3-(O)2-
C6H4}]4 (2b), which were separated by repeated fractional
crystallization and column chromatography. The reaction of
dimer 2a with H2O2 and selenium produces tetrachalcogenides
[{(O)P(μ-NtBu)}2{1,3-(O)2-C6H4}]2 (3) and [{(Se)P(μ-
NtBu)}2{1,3-(O)2-C6H4}]2 (4), respectively. The reaction
between the dimer (2a) and [Pd(μ-Cl)(η3-C3H5)]2 or
AuCl(SMe2) yielded the corresponding tetranuclear com-
plexes, [{((Cl)(η3-C3H5)Pd)P(μ-NtBu)}2{1,3-(O)2-C6H4}]2 (5) and [{(ClAu)P(μ-NtBu)}2{1,3-(O)2-C6H4}]2 (6) in good
yield. The complexes 5 and 6 are the rare examples of phosphorus macrocycles containing two or more exocyclic transition metal
fragments. Treatment of 1 with copper halides in 1:1 molar ratio resulted in the formation of one-dimensional (1D) coordination
polymers, [(CuX){1,3-C6H4{OP(μ-NtBu)2PN(H)tBu}}2]n (7, X = Cl; 8, X = Br; 9, X = I), which showed the helical structure in
solid state because of intramolecular hydrogen bonding, whereas similar reactions of 1 with 4 equiv of copper halides also
produced 1D-coordination polymers, [(Cu2X2)2{1,3-C6H4{OP(μ-NtBu)2PN(H)tBu}2}]n (10, X = Cl; 11, X = Br; 12, X = I), but
containing Cu2X2 rhomboids instead of CuX linkers. The crystal structures of 1, 2a, 2b, 4, 7−9, and 12 were established by X-ray
diffraction studies.
to trimetallic (I to IV)8 or tetrametallic cuboid complexes of the
INTRODUCTION
The cyclodiphosphazanes or diazadiphosphetidines of the type
[XP(μ-NR)]2 have proved as both neutral and anionic ligands
■
type VIII,9 whereas the short-bite bis(phosphine)s prefer ladder
(V), stair step tetrameric (VII), or 1D-coordination polymeric
(VII) structures.10 Some bidentate ligands have also shown an
unusual tetrameric structure of the type IX with all the four
copper atoms in one plane.11
toward both main group and transition elements.1 In addition,
these four membered rings have been employed as building
blocks in the formation of a range of inorganic macrocycles,2 as
mechanistic probes for organic reactions,3 and, in catalytic4 and
biological applications.5 Planar geometry, preference for cis-
conformation of phosphorus substituents, choice of metals, and
selectivity in coordination modes make them versatile bridging
ligands for the construction of polynuclear metalomacrocycles,6
chains, or one- (1D), two- (2D), and three-dimensional (3D)
coordination polymers.7
Recently we have investigated the Group 11 metal chemistry
of a few derivatives of cyclodiphosphazanes. The interaction of
cyclodiphosphazanes with copper halides in η1 fashion led to
the formation of mononuclear copper complexes (X), whereas
the bridged bidentate mode afforded oligomeric (XI) or
polymeric structures (XII), with P2N2 rings and rhomboid
Cu2X2 units linked alternatively.12 So far, the stoichiometry
controlled reactions have yielded products of the type X−XII,
and to get some insight into the various building blocks that
can be generated during molecular assembly, attempts are being
made to synthesize the products of the type XII and XIV.
Herein, we report the synthesis, structural characterization,
Copper(I) halides, in particular cuprous iodide (CuI), display
a wide range of structures (Chart 1) when coordinated to
phosphorus based ligands. The coordination number of
copper(I) is generally three or four and often the donor
solvents occupy one of the coordination sites when copper(I)
assumes open structure. Tertiary phosphines with moderate
steric bulk when reacted with CuX, depending on the reaction
conditions and the solvent employed, form either simple mono-
Received: March 13, 2012
Published: May 7, 2012
© 2012 American Chemical Society
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Chart 1. Possible Structural Motifs for Copper(I) Halide-Soft Ligand Complexes
oxidation reactions, and coordination behavior of a dimeric
acyclic cyclodiphosphazane as well as dimeric and tetrameric
macrocycles of cyclodiphosphazanes derived from resorcinol.
col.13 A similar derivative of cyclodiphosphazane, 1,3-
C6H4[OP(μ-NtBu)2PN(H)tBu]2 (1) (Scheme 1), having rigid
aromatic backbone was obtained by the reaction of cis-[ClP(μ-
NtBu)2PN(H)tBu] with resorcinol in diethyl ether in the
presence of triethyl amine at 0 °C as a white crystalline solid in
good yield. The ligand 1 is moderately air stable and soluble in
most of the organic solvents. The 31P NMR spectrum of 1
exhibits two singlets at 100.1 and 129.7 ppm, for amino-P
(hereafter “outer”) and aryloxo-P (hereafter “inner”) atoms,
RESULTS AND DISCUSSION
■
Synthesis of 1,3-C6H4[OP(μ-NtBu)2PN(H)tBu]2 (1). Re-
cently, we reported the synthesis of an acyclic dimer of
cyclodiphosphazane [CH2OP(μ-NtBu)2PN(H)tBu]2 by the
reaction of cis-[ClP(μ-NtBu)2PN(H)tBu] with ethylene gly-
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1
resonance at 146.0 ppm. In the H NMR spectrum, a singlet
was observed at 1.35 ppm for tert-butyl groups of 2b. The
elemental analysis data of 2a and 2b were in accordance with
the proposed structures. The structures of 2a and 2b were
further confirmed by single-crystal X-ray diffraction studies.
Oxidation Reactions of [{P(μ-NtBu)}2{1,3-(O)2-C6H4}]2
(2a). The reaction of [{P(μ-NtBu)}2{1,3-(O)2-C6H4}]2 (2a)
with H2O2 in tetrahydrofuran (THF) at room temperature
leads to the oxidation of all the four phosphorus atoms to give
[{(O)P(μ-NtBu)}2{1,3-(O)2-C6H4}]2 (3) in quantitative yield.
The 31P NMR spectrum of 3 shows a singlet at −11.9 ppm.
The reaction of 2a with 4 equiv of selenium in toluene under
refluxing condition furnished the tetrakis(selenide), [{(Se)P(μ-
Scheme 1
Scheme 2
respectively. In the 13C NMR spectrum two virtual triplets at
52.2 (2JPC = 13.1 Hz) and 31.5 ppm (3JPC = 6.3 Hz) were
assigned to tert-butyl groups on endocyclic nitrogen atoms,
whereas two doublets at 51.5 (2JPC = 14.1 Hz) and 32.9 ppm
(3JPC = 9.2 Hz) were assigned to tert-butyl groups attached to
exocyclic nitrogen atoms. The mass spectrum of 1 shows the
molecular ion peak at m/z 661.1 (M+1). Further evidence for
structure and molecular composition of 1 came from 1H NMR
spectrum, microanalysis, and single-crystal X-ray diffraction
study.
Dimeric and Tetrameric Derivatives: [{P(μ-NtBu)}{1,3-
(O)2C6H4}]2 (2a) and [{P(μ-NtBu)}2{1,3-(O)2-C6H4}]4 (2b).
The condensation of [ClP(μ-NtBu)]2 with bifunctional organic
alcohols, amines, or amino-alcohols (LL′H2), produce a broad
range of macrocycles [{P(μ-NtBu)}2(LL′)]n (n = 1−5).14 The
size of the macrocycle depends largely on the size, position of
reaction site and orientation of the organic linker (see
Supporting Information, Chart S1). Reaction conditions also
play a significant role in producing selectivity. Monomers are
generally formed with more flexible organic spacers, while rigid
organic spacers favor higher oligomers. The reaction of cis-
[ClP(μ-NtBu)]2 with resorcinol in diethyl ether at 0 °C, in the
presence of triethyl amine afforded a mixture of dimeric and
tetrameric compounds, [{P(μ-NtBu)}2{1,3-(O)2-C6H4}]2 (2a)
and [{P(μ-NtBu)}2{1,3-(O)2-C6H4}]4 (2b) (Scheme 1), along
with a small quantity of hydrolyzed and oxidized products,
substantiated by 31P NMR spectroscopic data. Repeated
fractional crystallization from toluene resulted in the isolation
of dimer 2a in low yield. The separation of tetramer by the
same method was unsuccessful as it was always contaminated
with small percentage of dimer cocrystallizing with the
tetramer. The attempts to separate the crystals have also
been unsuccessful because of the similar crystal morphology.
However, the mixture containing 2a and 2b on passing through
a silica gel column, using n-hexanes and dichloromethane as
eluent, under nitrogen atmosphere followed by recrystallization
from toluene gave both the compounds 2a and 2b in pure
form, from the respective fractions. The 31P NMR spectrum of
NtBu)}2{1,3-(O)2-C6H4}]2 (4), in good yield (Scheme 2). The
31P NMR spectrum of 4 exhibits a singlet at 32.7 ppm with 77Se
satellites attributed to the AA′X spin system typical for selenide
1
derivatives of cis-cyclodiphosphazanes. The JPSe is 996 Hz,
2
whereas the JPP is 7.3 Hz. The coupling constants were
comparable to that found in cis-[tBuNP(Se)(OCH2CH2-
2
OMe)]2 (1JPSe = 953 Hz, JPP = 6.7 Hz), cis-[tBuNP(Se)-
(OCH2CH2SMe)]2 (1JPSe = 954 Hz, JPP = 6.8 Hz)15 and cis-
2
[tBuNP(Se)(OMe)]2 (1JPSe = 954.5 Hz, JPP = 8.0 Hz).16 The
2
structure of 4 was confirmed by single-crystal X-ray structure
determination.
Palladium and Gold Complexes. Treatment of [Pd(μ-
Cl)(η3-C3H5)]2 with 2a in 2:1 molar ratio in dichloromethane
under reflux conditions gave a tetra-palladium complex
[{(Cl)(η3-C3H5)PdP(μ-NtBu)}2{1,3-(O)2-C6H4}]2 (5) in
good yield. The reaction between 2a and 4 equiv of
[AuCl(SMe2)] in dichloromethane resulted in the formation
of tetragold complex [{(ClAu)P(μ-NtBu)}2{1,3-(O)2-C6H4}]2
(6). The 31P NMR spectrum of 5 shows two broad singlets at
122.7 and 115.0 ppm which may be due to the improper
folding of dimeric macrocyle after complexation. Because of the
poor solubility of complex 5, low-temperature NMR studies
could not be carried out. In contrast, the 31P NMR spectrum of
6 shows a single resonance at 98.4 ppm indicating the
1
symmetrical nature of all phosphorus atoms. In the H NMR
1
1
2a shows a single resonance at 131.5 ppm. In the H NMR
spectrum tert-butyl groups show a singlet at 1.57 ppm. The H
spectrum of 2a, a singlet was observed at 1.27 ppm for tert-
assignments and microanalysis data are found to be consistent
with the proposed structures in all cases.
butyl groups. The 31P NMR spectrum of 2b shows a single
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Synthesis of Copper(I) Complexes. The treatment of 1
equiv of copper halide (CuCl, CuBr, or CuI) with ligand 1 in a
1:1 mixture of dichloromethane and acetonitrile yielded
coordination polymers [{1,3-C6H4(OP(μ-NtBu)2PN-
(H)tBu)2}(CuX)]n (7, X = Cl; 8, X = Br; 9, X = I) in good
yield. The complexes were precipitated from the reaction
mixture as insoluble white solids. In these polymers, copper
centers are found to be coordinated by one inner and one outer
phosphorus atom from two cyclodiphosphazanes in a zigzag
fashion. The 31P NMR spectra of 7−9 are identical and show
four broad signals in the range of 139.4−67.2 ppm, indicating
the presence of four different types of phosphorus centers in
each complex. For example, in case of 7, single resonances at
135.6 ppm and 98.7 ppm are assigned respectively to
uncoordinated inner-phosphorus and coordinated inner-
phosphorus, while high field signals at 73.8 and 67.2 ppm are
assigned, to uncoordinated and coordinated outer-phosphorus
centers, respectively. The product formation was found to be
independent of stoichiometry of the reactants as both 1:1 and
1:2 reactions led to the formation of the same product. Because
of the poor solubility of all the polymeric compounds and the
presence of quadrupolar nuclei, all the peaks in 31P NMR
spectra appeared broad, and low temperature NMR studies
could not carried out.
Figure 1. Molecular structure of [1,3-C6H4OP(μ-NtBu)2PN(H)tBu]2
(1). Thermal ellipsoids are drawn at the 50% probability level.
Hydrogen atoms have been omitted for clarity. Symmetry operations
(i) −x, −y, −z (ii) 1/2−x, 1/2−y, −z.
The treatment of ligand 1 with 4 equiv of copper halide
(CuCl, CuBr or CuI) produced copper(I) coordination
polymers [{1,3-C6H4(OP(μ-NtBu)2PN(H)tBu)2}{(Cu2(μ-
X)2}2]n (10, X = Cl; 11, X = Br; 12, X = I). The compounds
10−12 are poorly soluble in most of the organic solvents, but
partially soluble in hot dimethylsulfoxide (DMSO). In the
coordination polymers 10−12, one [Cu2(μ-X)2] rhombic unit
is coordinated by two inner phosphorus atoms, whereas the
two outer phosphorus atoms from two cyclodiphosphazane
ligands are held together by [Cu2(μ-X)2] units resulting in the
formation of 1D-coordination polymers. The 31P NMR spectra
of 10−12 show three broad resonances in the range of 66.2−
107.9 ppm. For example, in case of 10, a signal at 107.9 ppm is
assigned to coordinated inner-phosphorus atoms and broad
resonances at 80.0 and 66.5 ppm are assigned to coordinated
outer-phosphorus atoms. The polymeric structures of com-
plexes 7−9 and 12 in the solid state have been revealed by the
X-ray diffraction studies.
Molecular Structures of Compounds 1, 2a, 2b, 4, 7−9,
and 12. Perspective views of the molecular structures of all
compounds with the atom numbering schemes are shown in
Figures 1−9. Crystal data and the details of the structure
determinations are given in Table 1 while the selected bond
lengths and the interbond angles appear in Tables 2 and 3.
The crystals suitable for X-ray diffraction study were obtained
from toluene solution of 1 at −20 °C. Normally the longer P−
Figure 2. Molecular structure of [{P(μ-NtBu)}2{1,3-(O)2-C6H4}]2
(2a). Thermal ellipsoids are drawn at the 50% probability level. All
hydrogen atoms have been omitted. Symmetry operation (i) −x, −y, −
z.
N bonds are associated with phosphorus atom having an
exocyclic nitrogen substituent, whereas phosphorus bearing
oxo-, alkoxo-, aryloxo-, or halo- substituents show shorter P−N
bond distances.17 The average endocyclic P−N bond distance
of phosphorus bearing an aryloxo- substituent is 1.697 Å,
whereas the average P−N bond distance, where phosphorus is
bound to exocyclic nitrogen is 1.738 Å. The exocyclic P2−N3
bond distance [1.6480(15) Å] is shorter than endocyclic P−N
bond distances. The exocyclic P−N distances are always shorter
and comparable with typical P−N distances observed in both
cyclic and acyclic diphosphazanes.1d The P1−O1 bond distance
in 1 [1.6705(13) Å] is slightly longer than that found in
13
[CH2OP(μ-NtBu)2PN(H)tBu]2 [1.6383)(14) Å], Et2C-
[CH2OP(μ-NtBu)2PN(H)tBu]2 [1.629(2) Å], and C[CH2OP-
2e
(μ-NtBu)2PN(H)tBu]4 [1.630(4) Å], but comparable with
the same in [tBu(H)NP(μ-NtBu)2POC6H4PPh2-o] [1.6881(11)
Å].18 The P2N2 rings in 1 are puckered with a folding along
N···N axis, as indicated by the dihedral angle between the
corresponding N−P−N planes [∼8.1°].
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[97.64(19)−97.9(2)°] and 2b [97.33(7)−98.27(7)°] are
almost identical and similar to those of [{P(μ-NtBu)}2(μ-
O)]4 [P−N, 1.700(2)−1.732(2) Å and P−N−P, 96.73(9)−
99.2(1)°].
The X-ray quality crystals of 4 were obtained from
dichloromethane/pet-ether solution of 4 at room temperature.
The structural features of 4 are similar to its starting compound
2a. The mean planes of two aromatic rings and P2N2 rings are
parallel to each other. The average P−O and P−N bond
distances in 4 are 1.601 Å and 1.685 Å, are shorter than those
of P(III) derivative, 2a. Similar trends, that is, shrinking of P−O
and P−N distances from PIII derivative to PV derivative were
observed in the analogues [(2,2′-C10H6O){(O)P(μ-NtBu)}2]2b
and [tBuHN(tBuNP(Se))2OCH2]2.13
Crystals of 7−9 and 12 suitable for X-ray diffraction were
obtained by slow diffusion of copper halide solution in
acetonitrile into a dichloromethane solution of 1 at room
temperature. The compounds 7 and 9 crystallize in the
orthorhombic crystal system, whereas 8 crystallizes in the
monoclinic crystal system. The unit cell of the complex 7
contains two independent half molecules, with similar bonding
properties. All copper atoms in 7−9 are tricoordinated and
adopt a distorted trigonal planar geometry. The copper centers
are coordinated by the inner phosphorus of one molecule and
the outer phosphorus of other molecule of ligand, forming 1D
coordination polymers. The tricoordinated copper centers in
7−9 are planar as suggested by the sum of the bond angles
around copper centers (359.9°) in all the three cases. The Cu−
P and Cu−X bond lengths are in good agreement with the
literature values for tricoordinated copper(I)−phosphine
complexes.20 The P1−Cu−P3 bond angles in 7 [119.30(5)°],
8 [118.24(3)°], and 9 [120.13(6)°] are similar, and they
indicate little or no influence of halogen atoms on the geometry
around copper. The P1−Cu−P3 bond angles in 7−9 are less
than the P−Cu−P bond angles reported in literature for
tricoordinated copper complexes of both less bulkier phosphine
ligands such as PPh3 [125.48(7)°]21 and bulkier ligands such as
Figure 3. Molecular structure of [{P(μ-NtBu)}2{1,3-(O)2-C6H4}]4
(2b). Thermal ellipsoids are drawn at the 50% probability level.
Hydrogen atoms have been omitted for clarity. Symmetry operation
(i) −x,−y,−z.
7
cis-[tBuNP(OC6H4OMe-o)]2 [130.11(2)°], PCy3 [134.44(8)
°],20 and PBn3 [136.53(2)°].22 This is due to the intra-
molecular hydrogen bonding between N−H and oxygen atom
(see Supporting Information, Figure S1). The hydrogen bond
distance in 8 is 2.0834(19) Å and the N−H---O bond angle is
163.53°; similarly, in case of 7 and 9, the hydrogen bond
distances are 2.2697(27) Å and 2.1752(36) Å, and the N−H---
O bond angles are 169.40° and 164.34°, respectively. The
intramolecular hydrogen bonding not only reduces the P1−
Cu−P3 bond angle but it has greater effect on the solid state
structure of these complexes as it guides the polymers to form a
helical structure as shown in Figure 9.
The structure of polymer 12 consists of two different
rhombic [Cu2(μ-I)2] cores in it. In the [Cu1(μ-I1,I2)Cu2]
dimeric unit, one of the copper centers is tricoordinated with
the coordination sites occupied by outer phosphorus atom of
the cyclodiphosphazane and two bridging iodide atoms whereas
the other copper center in the same unit is tetracoordinated, as
acetonitrile occupies the fourth coordination site. The
tricoordinated copper center, Cu2 adopts trigonal planar
geometry, whereas the tetracoordinated copper center, Cu1,
adopts a distorted tetrahedral geometry. Since there are
unsymmetrical interactions between the N−H hydrogen and
iodide atoms, all the four Cu−I bond lengths differ significantly
and can be roughly grouped into two sets with the longer
distances [2.6910(8) and 2.8168(6) Å] being associated with
Figure 4. Molecular structure of [{(Se)P(μ-NtBu)}2{1,3-(O)2-
C6H4}]2 (4). Thermal ellipsoids are drawn at the 50% probability
level. All hydrogen atoms have been omitted. Symmetry operation (i)
−x, −y, −z.
The low temperature X-ray diffraction studies unambiguously
established the structures of 2a and 2b. The compounds 2a and
2b crystallize in the monoclinic crystal system. The structure of
2a is similar to that previously reported [{P(μ-NtBu)}2{2,6-
(NH)2C5H3N}]2 by Wright and co-workers.5 The two P2N2
rings in 2a are nearly parallel to each other as indicated by the
angle between the mean planes of two rings [3.375 Å]. The
mean planes of alternative P2N2 rings are also parallel to each
other in 2b. The cavity of 2b measures 11.22 Å (mean)
between the centroids of the alternative P2N2 ring units. The
P2N2 rings are slightly puckered as indicated by their dihedral
angles between the corresponding N−P−N planes in 2a
[11.4°] and 2b [6.9° and 13.5°]. The average P−O bond
distances in 2a [1.658 Å] and 2b [1.661 Å] are similar and
comparable with those in {2,2′-(C10H6O)2}{P(μ-NtBu)}2
[1.664 Å]2b and [{P(μ-NtBu)}2(μ-O)]4 [1.654(2)−1.665(2)
Å].19 The P−N bond lengths in 2a [1.697(4)−1.724(4) Å] and
2b [1.7001(14)−1.7204(5) Å] and P−N−P bond angles in 2a
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Figure 5. Molecular structure of [{1,3-C6H4(OP(μ-NtBu)2PN(H)tBu)2}(CuCl)]n (7). Thermal ellipsoids are drawn at the 50% probability level. All
the hydrogen atoms and lattice solvents have been omitted for clarity. Only one orientation is shown for the disordered tert- butyl groups.
Figure 6. Molecular structure of [{1,3-C6H4(OP(μ-NtBu)2PN(H)tBu)2}(CuBr)]n (8). Thermal ellipsoids are drawn at the 50% probability level. All
the hydrogen atoms and lattice solvents have been omitted for clarity. Only one orientation is shown for the disordered tert- butyl groups. Symmetry
operation (i) −x, −y, −z.
Figure 7. Molecular structure of [{1,3-C6H4(OP(μ-NtBu)2PN(H)tBu)2}(CuI)]n (9). Thermal ellipsoids are drawn at the 50% probability level. All
the hydrogen atoms and lattice solvents have been omitted for clarity. Only one orientation is shown for the disordered tert- butyl groups. Symmetry
operation (i) −x, −y, −z.
the tetra-coordinated copper and the shorter set [2.5099(6)
and 2.5790(11) Å] with the tricoordinated copper. The
increase in the coordination number is responsible for the
increase in the bond angle from I1−Cu1−I2 [104.03(3)°] to
I1−Cu2−I2 [117.11(2)°].7a
In the symmetrical [Cu3(μ-I3,I4)Cu4] rhombic unit, the
copper centers are tetrahedrally coordinated by one inner
phosphorus, two iodine atoms, and one acetonitrile molecule.
The angles about metals are varying from 114.18(10)° for N8−
Cu3−P2 to 97.06(10)° for N8−Cu3−I3. The mean planes of
[Cu3(μ-I3,I4)Cu4] unit are inclined at an angle of 33.18° to
the plane of the aromatic ring. The Cu−I bond lengths are
almost identical, with the mean distance being 2.671 Å. The
Cu−I bond distances are in good agreement with the reported
value for the [Cu2(μ-I)2] unit, in [Cu2I2{tBuNP(OC6H4OMe-
o)}2]n,7a [Cu8(μ-I)8(CH3CN)4(μ-NtBuP)8(NC4H8NMe)8],6c
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3.3957(8) Å. This difference arises again as a result of the
increase in the coordination number from three to four. In both
the cases, the Cu···Cu distances are noticeably greater than the
sum of the van der Waals radii for the copper(I) ion, which
confirms the nonexistence of metallophilic interactions in
coordination polymer 12.
CONCLUSIONS
■
The stoichiometry controlled reactions of copper(I) halides
with tetradentate ligand 1 led to the formation of 1D
coordination polymers. The prediction of the structures of
products in the reactions of 1 with 1 equiv of copper(I) halides
were not easy, since there were four potential coordinating
phosphorus centers in close proximity, but because of the steric
and intramolecular hydrogen bonding, complexes 7−9 form 1D
chains and adopt helical structures in solid state. The 4 equiv of
copper(I) halides reacted differently with 1, though they gave
1D coordination polymers, the propagation of polymeric chain
is through the formation of rhombic [Cu(μ-X)]2 units.
Interestingly, in the lattice of complex 12, the nitrogen
bound tert-butyl groups from four neighboring units together
make a hydrophobic pocket to trap two dichloromethane
molecules. The dimer (2a) and tetramer (2b) were isolated
from the reaction of resorcinol with [ClP(μ-NtBu)]2.
Preliminary studies have shown that the dimer can act as a
tetradentate ligand. With carefully chosen transition metal
precursors, these macrocycles can form polynuclear clusters and
cages; some of which might mimic the properties of various
synthetic zeolites. The ligand 1 with the resorcinol moiety
bridging the two cyclodiphosphazane units was essentially
synthesized to employ as a pincer ligand to coordinate to
transition metal derivatives. It would be interesting to make
pincer complexes involving inner phosphorus centers and
ortho-CH activation, while the outer ones can function as either
neutral or anionic ligands to form heterometallic complexes.
The amide functionalities can also bind to early transition
metals in their high-valent states that might result in the
formation of simple dimeric to high nuclearity clusters or
multinuclear 3D-coordination polymers with cavities of
considerable size to trap selective organic molecules. The
work in these directions is in progress.
Figure 8. Helical structures of 7, 8, and 9.
and [Cu(μ-I)(dppp)]2.23 Both the rhombic [Cu2(μ-I)2] units
are puckered, but the deviation from planarity is more in case of
unsymmetrical [Cu1(μ-I1,I2)Cu2] [19.734(33)°] than sym-
metrical [Cu3(μ-I3,I4)Cu4] [9.360(16)°] unit. The Cu1···Cu2
distance is 2.9159(7) Å, whereas the Cu3···Cu4 distance is
EXPERIMENTAL SECTION
■
General Procedures. All manipulations were performed using
standard vacuum-line and Schlenk techniques under nitrogen
Figure 9. Molecular structure of [{1,3-C6H4(OP(μ-NtBu)2PN(H)tBu)2}{Cu2(μ-I)2}2]n (12). Thermal ellipsoids are drawn at the 50% probability
level. All the hydrogen atoms and lattice solvents have been omitted for clarity. Only one orientation is shown for the disordered tert- butyl groups.
Symmetry operations (i) −x, −y, −z. (ii) 1/2−x, 1/2−y, −z.
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Table 2. Selected Bond Distances (Å) and Bond Angles (deg) for 1, 2a, 2b, and 4
compound 1
compound 2a
bond length (Å)
bond angle (deg)
O1−P1−N1
bond length (Å)
P1−O1
bond angle (deg)
N1−P1−N2 81.28(18)
P1−O1
1.6705(13)
1.6990(14)
1.6941(14)
1.7362(14)
1.7406(14)
1.6480(15)
1.384(2)
104.56(6)
104.85(6)
82.37(6)
79.98(6)
103.52(7)
105.31(7)
98.25(7)
1.662(3)
1.709(4)
1.706(4)
1.647(3)
1.706(4)
1.715(4)
1.653(3)
P1−N1
P1−N2
P2−N1
P2−N2
P2−N3
O1−C1
O1−P1−N2
N1−P1−N2
N1−P2−N2
N1−P2−N3
N2−P2−N3
P1−N1−P2
P1−N1
P1−N2
P2−O2
P2−N1
P2−N2
P4−O4
O1−P1−N1
O1−P1−N2
P1−N1−P2
O2−P2−N1
O3−P3−N3
N3−P4−N4
O4−P4−N4
P3−N4−P4
105.32(17)
99.15(16)
97.8(2)
109.94(19)
98.84(15)
80.37(18)
110.47(17)
97.88(19)
compound 2b
compound 4
bond length (Å)
bond angle (deg)
bond length (Å)
bond angle (deg)
P1−N1
P1−N2
P1−O4
P2−O1
P3−O2
P4−O3
1.7000(14)
1.7091(14)
1.6598(13)
1.6614(12)
1.6673(12)
1.6551(15)
N1−P1−N2
O4−P1−N1
O1−P2−N2
O2−P3−N3
N3−P3−N4
O3−P4−N3
81.77(7)
100.54(6)
105.72(6)
103.78(6)
80.88(7)
107.48(7)
Se1−P1
Se2−P2
P1−O1
P1−N1
P1−N2
P2−O2
2.0670(4)
2.0631(4)
1.5981(11)
1.6816(14)
1.6832(13)
1.6039(11)
N1−P2−N2
O1−P1−N1
O1−P1−N2
P1−N1−P2
O2−P2−N1
O2−P2−N2
Se1−P1−P2
Se1−P1−O1
Se1−P1−N1
83.95(6)
103.25(6)
106.01(6)
95.10(6)
110.24(6)
110.63(6)
128.04(2)
115.22(4)
120.84(4)
Table 3. Selected Bond Distances (Å) and Bond Angles (deg) for 7, 8, 9, and 12
compound 7
compound 8
bond length (Å)
bond angle (deg)
P1−Cu1−P3
bond length (Å)
Cu−Br1
bond angle (deg)
Cu1−P3
2.2101(14)
2.1970(14)
2.2300(14)
1.712(4)
119.30(5)
117.80(5)
122.88(5)
115.38(15)
109.61(15)
114.0(2)
2.3454(5)
2.2431(9)
2.2516(9)
1.660(2)
1.672(2)
1.677(2)
1.746(2)
1.719(2)
1.673(2)
Br1−Cu1−P1
Br1−Cu1−P3a
P1−Cu1−P3a
Cu1−P1−O1
Cu1−P1−N1
Cu1−P1−N2
N1−P1−N2
N1−P2−N2
N1−P2−N3
117.48(3)
124.26(3)
118.24(3)
104.14(7)
130.83(9)
122.14(9)
84.30(12)
79.71(11)
104.61(13)
Cu1−Cl1
Cu1−P1
P1−N2
P1−N1
P1−N3
P2−O2
P3−O1
Cl1−Cu1−P1
Cl1−Cu1−P3
Cu1−P1−N2
Cu1−P1−N3
N2−P1−N3
Cu1−P3−N5
Cu1−P3−O1
Cu1−P3−N4
Cu1−P1
Cu1−P3
P1−O1
P1−N1
P1−N2
P2−N1
P3−N4
P4−O2
1.703(4)
1.647(4)
1.673(4)
122.25(15)
105.38(11)
129.65(14)
1.668(3)
compound 9
compound 12
bond length (Å)
bond angle (deg)
bond length (Å)
bond angle (deg)
Cu1−I1
Cu1−P2
Cu1−P4
P1−N1
P1−N2
P1−N3
P2−O1
P2−N1
P3−O2
2.4878(9)
2.2279(16)
2.2518(16)
1.755(4)
1.756(4)
1.651(4)
1.659(4)
1.670(4)
1.678(4)
I1−Cu1−P2
I1−Cu1−P4
P2−Cu1−P4
N1−P1−N2
N1−P1−N3
N2−P1−N3
Cu1−P2−O1
Cu1−P2−N1
Cu1−P2−N2
O1−P2−N1
120.75(5)
119.07(4)
120.13(6)
79.40(19)
103.7(2)
I1−Cu1
I1−Cu2
I2−Cu1
I2−Cu2
I3−Cu3
I3−Cu4
I4−Cu3
Cu1−N7
Cu1−P4
Cu2−P1
Cu3−P2
Cu3−N8
Cu4−P3
Cu4−N9
2.8168(6)
2.5099(6)
2.6910(8)
2.5790(11)
2.6681(6)
2.6668(6)
2.6798(6)
1.999(3)
Cu1−I1−Cu2
Cu1−I2−Cu2
Cu3−I3−Cu4
Cu3−I4−Cu4
I1−Cu1−I2
I1−Cu1−N7
I4−Cu4−P3
I1−Cu2−P1
I2−Cu2−P1
I3−Cu3−I4
I3−Cu3−N8
I4−Cu3−P2
I3−Cu4−I4
I3−Cu4−N9
66.09(1)
67.15(2)
79.06(2)
78.79(1)
104.03(3)
96.15(10)
118.66(3)
128.19(3)
114.54(3)
100.19(2)
97.06(10)
117.59(3)
100.45(2)
103.97(9)
105.7(2)
103.48(14)
130.02(16)
124.09(15)
105.9(2)
2.2291(11)
2.2151(10)
2.2077(10)
2.040(3)
2.2149(10)
2.053(4)
atmosphere unless otherwise stated. All of the solvents were purified
by conventional procedures24 and distilled prior to use. The
compounds cis-[tBuHN(tBuNP)2Cl],25 cis-[ClP(μ-NtBu)]2,25 AuCl-
(SMe2),26 [Pd(η3-C3H5)Cl]2,27 CuCl,28 and CuBr28 were prepared
according to the published procedures. CuI was purchased from
Aldrich chemicals and used as such without further purification. Other
chemicals were obtained from commercial sources and purified prior
to use.
Instrumentation. The NMR spectra were recorded at the
following frequencies: 400 MHz (1H), 100 MHz (13C), 162 MHz
(31P) using either Varian VXR 400 or Bruker AV 400 spectrometers.
13C and 31P NMR spectra were acquired using broad band decoupling.
The spectra were recorded in CDCl3 (or DMSO-d6) solutions with
1
CDCl3 (or DMSO-d6) as an internal lock; chemical shifts of H and
13C NMR spectra are reported in ppm downfield from TMS, used as
internal standard. The chemical shifts of 31P NMR spectra are referred
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to 85% H3PO4 as external standard. The microanalyses were
performed using a Carlo Erba Model 1112 elemental analyzer. Mass
spectra were recorded using Waters Q-Tof micro (YA-105). The
melting points were observed in capillary tubes and are uncorrected.
Synthesis of [1,3-C6H4{OP(μ-NtBu)2PN(H)tBu}2] (1). A mixture
of resorcinol (0.375 g, 3.4 mmol) and triethylamine (0.84 g, 1.2 mL,
8.3 mmol) in diethyl ether (25 mL) was added dropwise to an ice cold
solution of cis-[ClP(μ-NtBu)2PN(H)tBu] (2.14 g, 6.8 mmol) also in
diethyl ether (25 mL). After the completion of the addition, the
reaction mixture was stirred for 12 h at room temperature and then
filtered through Celite to remove amine hydrochloride salt. Solvent
was removed under reduced pressure to obtain 1 as a white solid,
which was then recrystallized from toluene. Yield: 89% (2.0 g). Mp:
94−96 °C. Anal. Calcd for C30H60N6O2P4: C, 54.53; H, 9.15; N, 12.72.
reflux for 10 h. The solvent was removed under reduced pressure, to
get 5 as an off-white solid. Yield: 75% (0.044 g). Mp: >210 °C (dec).
Anal. Calcd for C40H64Cl4N4O4P4Pd4: C, 35.42; H, 4.76; N, 4.13.
1
Found: C, 35.31; H, 4.92; N, 4.09. H NMR (400 MHz, CDCl3): δ
7.83 (s, ArH, 2H), 7.40−6.81 (m, br, ArH, 6H), 5.74−5.30 (m, br,
CH2, 4H), 4.76 (m, CH2, 6H), 3.76 (m, CH2, 6H), 3.19 (t, J = 14.6
t
Hz, CH2, 4H), 1.57−1.43 (m, Bu, 36H). 31P{1H} NMR (162 MHz,
CDCl3): δ 122.7 (br, s), 115.0 (br, s).
Synthesis of [{(ClAu)P(μ-NtBu)}2{1,3-(O)2-C6H4}]2 (6). A di-
chloromethane (10 mL) solution of AuCl(SMe2) (0.047 g, 0.16
mmol) was added dropwise over a well-stirred solution (10 mL) of
[{P(μ-NtBu)}2{1,3-(O)2-C6H4}]2 (2a) (0.025 g, 0.04 mmol) at room
temperature. The reaction mixture was stirred further for 5 h under
minimum exposure of light, and then solvent was removed under
vacuum, washed with 2 × 5 mL of pet ether, to get an analytically pure
white solid. Yield: 81% (0.049 g). Mp: >270 °C (dec). Anal. Calcd for
C28H44Au4Cl4N4O4P4: C, 21.64; H, 2.85; N, 3.60. Found: C, 21.56; H,
2.83; N, 3.46. 1H NMR (400 MHz, CDCl3): δ 7.89 (s, ArH, 2H), 7.43
1
Found: C, 54.17; H, 9.19; N, 12.65. H NMR (400 MHz, CDCl3): δ
7.19 (t, 3JHH = 8 Hz, ArH, 1H), 6.80−6.83 (m, ArH, 3H), 2.42 (d, NH,
t
t
2JPH = 8 Hz, 2H), 1.34 (s, Bu, 36H), 1.12 (s, Bu, 18H). 13C{1H}
2
NMR (100 MHz, CDCl3): 153.5, 127.9, 118.1, 117.9, 52.2 (vt, JPC
=
13.1 Hz), 51.5 (d, JPC = 14.1 Hz), 32.9 (d, JPC = 9.2 Hz), 31.5 (vt,
(s, br, ArH, 2H), 7.24 (s, br, ArH, 4H), 1.57 (s, Bu, 36H). 31P{1H}
2
3
t
3JPC = 6.3 Hz). 31P{1H} NMR (162 MHz, CDCl3): δ 129.7 (s), 100.1
NMR (162 MHz, CDCl3): δ 98.4 (s).
Synthesis of [{1,3-C6H4(OP(μ-NtBu)2PN(H)tBu)2}(CuCl)]n (7). A
solution of cuprous chloride (0.0066 g, 0.0666 mmol) in acetonitrile
(5 mL) was added dropwise to a solution of 1 (0.044 g, 0.0666 mmol)
also in dichloromethane (5 mL). The reaction mixture was allowed to
stir at room temperature for 4 h. The resulting white precipitate was
washed with 5 mL of petroleum ether, to get analytical pure 7 as white
powder. Yield: 85% (0.043 g). Mp: 155−158 °C. Anal. Calcd for
C31.25H62Cl1.5CuN6.5O2P4 C, 46.83; H, 7.80; N, 11.36. Found: C,
(s). MS (EI): m/z = 661.1 (M+1).
Synthesis of [{P(μ-NtBu)}2{1,3-(O)2-C6H4}]2 (2a) and [{P(μ-
NtBu)}2{1,3-(O)2-C6H4}]4 (2b). A mixture of resorcinol (1.2 g, 10.9
mmol) and triethylamine (2.77 g, 3.9 mL, 27.42 mmol) in diethyl
ether (50 mL) was added dropwise to an ice-cold solution of cis-
[ClP(μ-NtBu)]2 (3.0 g, 10.9 mmol) also in diethyl ether (30 mL).
After the completion of the addition, the reaction mixture was stirred
for 12 h at room temperature and then filtered through Celite to
remove amine hydrochloride salt. Solvent was removed under vacuum
to obtain product as a white solid. The crude mixture was passed
through a silica gel column using 9:1 mixture of pet-ether and
dichloromethane as eluent, and both fractions were recrystallized from
toluene.
1
46.79; H, 7.72; N, 11.27. H NMR (400 MHz, CDCl3): δ 7.10−6.50
t
t
(m, ArH, 4H), 4.67 (br, s, NH, 2H), 1.57 (s, Bu, 36H), 1.38 (s, Bu,
18H). 31P{1H} NMR (162 MHz, CDCl3): δ 135.6 (br, s), 98.7 (br, s),
73.8 (br, s), 67.2 (br, s).
Synthesis of [{1,3-C6H4(OP(μ-NtBu)2PN(H)tBu)2}(CuBr)]n (8).
Compound 8 was synthesized by a procedure similar to that of 7 using
cuprous bromide (0.0062 g, 0.0216 mmol) and 1 (0. 029 g, 0.0216
mmol). Yield: 82% (0.029 g). Mp: 200−202 °C. Anal. Calcd for
C30H60CuBrN6O2P4: C, 44.80; H, 7.52; N, 10.45. Found: C, 44.78; H,
Yield (2a): 26% (0.9 g). Mp: 106−108 °C. Anal. Calcd for
C56H88N8O8P8: C, 53.85; H, 7.10; N, 8.97. Found: C, 53.77; H, 7.11;
1
N, 9.02. H NMR (400 MHz, CDCl3): δ 8.39 (s, ArH, 2H), 7.12 (t,
3
t
3JHH = 8 Hz, ArH, 2H), 6.74 (d, JHH = 8 Hz, ArH, 4H), 1.27 (s, Bu,
36H). 31P{1H} NMR (162 MHz, CDCl3): δ 131.5 (s). MS (EI): m/z
= 625.2 (M+1+).
1
7.39; N, 10.34. H NMR (400 MHz, DMSO-d6): δ 7.30−6.61 (m,
t
ArH, 4H), 4.70 (br, s, NH, 2H), 1.41−1.30 (m, Bu, 54H). 31P{1H}
Yield (2b): 20% (0.7 g). Mp: 120−124 °C. Anal. Calcd for
NMR (162 MHz, DMSO-d6): δ 139.4 (br, s), 101.3 (br, s), 71.4 (br,
s).
C56H88N8O8P8: C, 53.85; H, 7.10; N, 8.97. Found: C, 53.69; H, 6.97;
1
3
N, 8.83. H NMR (400 MHz, CDCl3): δ 7.17 (t, JHH = 8 Hz, ArH,
Synthesis of [{1,3-C6H4(OP(μ-NtBu)2PN(H)tBu)2}(CuI)]n (9).
Compound 9 was synthesized by a procedure similar to that of 7
using cuprous iodide (0.0104 g, 0.0546 mmol) and 1 (0.036 g, 0.0546
mmol). Yield: 84% (0.039 g). Mp: 175−178 °C. Anal. Calcd for
C30H60CuIN6O2P4: C, 42.33; H, 7.10; N, 9.87. Found: C, 42.16; H,
6.95; N, 9.69. 1H NMR (400 MHz, DMSO-d6): δ 7. 65 (m, ArH, 4H),
4H), 6.85−6.94 (m, ArH, 12H), 1.35 (s, Bu, 36H). 31P{1H} NMR
t
(162 MHz, CDCl3): δ 146.0 (s).
Synthesis of [{OP(μ-NtBu)}2{1,3-(O)2-C6H4}]2 (3). A 30%
aqueous solution of H2O2 (0.007 g, 0.021 mL, 0.206 mmol) in THF
(5 mL) was added dropwise to a well-stirred THF solution (10 mL) of
2a (0.03 g, 0.048 mmol). The reaction mixture was stirred for 5 h at
room temperature. The solvent was removed under reduced pressure
to give 3 as off-white solid. Yield: 85% (0.028 g). Mp: 168−172 °C.
HRMS Calc for C28H45N4O8P4: 689.2188, Found: 689.2172. 1H NMR
(400 MHz, CDCl3): δ 7.83 (t, 3JHH = 2.4 Hz ArH, 2H), 7.42−7.36 (m,
t
4,89 (br, s, NH, 2H), 1.43−1.23 (m, Bu, 54H). 31P{1H} NMR (162
MHz, DMSO-d6): δ 134.5 (br, s), 97.6 (br, s), 72.3 (br, s), 67.9 (br, s).
Synthesis of [{1,3-C6H4(OP(μ-NtBu)2PN(H)tBu)2}{Cu2(μ-Cl)2}2]n
(10). Compound 10 was synthesized by a procedure similar to that of
7 using cuprous chloride (0.018 g, 0.182 mmol) and 1 (0.03 g, 0.0454
mmol). Yield: 85% (0.041 g). Mp: 219−222 °C. Anal. Calcd for
C36H69Cu4Cl4N9O2P4.2CH2Cl2: C, 33.81; H, 5.45; N, 9.33. Found: C,
33.63; H, 5.37; N, 9.25. 1H NMR (400 MHz, DMSO-d6): δ 7.80−6.85
t
ArH, 6H), 1.39 (s, Bu, 36H). 31P{1H} NMR (162 MHz, CDCl3):
−11.9 (s). MS (EI): m/z = 689.2 (M+1).
Synthesis of [{SeP(μ-NtBu)}2{1,3-(O)2-C6H4}]2 (4). A mixture
of [{P(μ-NtBu)}2{1,3-(O)2-C6H4}]2 (2a) (0.04 g, 0.064 mmol) and
selenium (0.021 g 0.266 mmol) in 20 mL of toluene was refluxed for
24 h. Then the solution was cooled to room temperature and filtered
through Celite, and the solvent was removed under reduced pressure
to get compound 4 as a yellow crystalline solid. Yield: 89% (0.054 g).
Mp: >270 °C. Anal. Calcd for C28H44N4O4P4Se4: C, 35.76; H, 4.72; N,
5.96. Found: C, 35.67; H, 4.65; N, 5.90. 1H NMR (400 MHz, CDCl3):
δ 7.83 (s, ArH, 2H), 7.36 (t, 3JHH = 8 Hz, ArH, 2H), 7.24 (d, 3JHH = 8
Hz, ArH, 4H), 1.60 (s, tBu, 36H). 31P{1H} NMR (162 MHz, CDCl3):
32.7 (s, 1JPSe = 996 Hz, 2JPP = 7.3 Hz). MS (EI): m/z = 940.3 (M+1).
Synthesis of [{(Cl)(η3-C3H5)PdP(μ-NtBu)}2{1,3-(O)2-C6H4}]2 (5).
A dichloromethane solution (10 mL) of [Pd(μ-Cl)(η3-C3H5)]2
(0.0316 mg, 0.0864 mmol) was added to [{P(μ-NtBu)}2{1,3-(O)2-
C6H4}]2 (2a) (0.027 g, 0.0432 mmol) in 10 mL of dichloromethane at
room temperature. The resultant turbid solution was stirred under
t
(m, ArH, 4H), 4.85 (br, s, NH, 2H), 1.57−1.30 (m, Bu, 54H).
31P{1H} NMR (162 MHz, DMSO-d6): δ 107.9 (br, s), 80.0 (br, s),
66.5 (br, s).
Synthesis of [{1,3-C6H4(OP(μ-NtBu)2PN(H)tBu)2}{Cu2(μ-Br)2}2]n
(11). Compound 11 was synthesized by a procedure similar to that of
7 using cuprous bromide (0.016 g, 0.112 mmol) and 1 (0.0184 g,
0.0278 mmol). Yield: 78% (0.027 g). Mp: >270 °C (dec). Anal. Calcd
for C36H69Cu4Br4N9O2P4: C, 31.85; H, 5.12; N, 9.28. Found: C, 31.87;
1
H, 5.25; N, 8.65. H NMR (400 MHz, DMSO-d6): δ 7.30−6.60 (m,
ArH, 4H), 4.70 (br, s, NH, 2H), 1.52 (s, tBu, 36H), 1.35 (s, tBu, 18H).
31P{1H} NMR (162 MHz, DMSO-d6): δ 106.5 (br, s), 78.6 (br, s),
66.2 (br, s).
Synthesis of [{1,3-C6H4(OP(μ-NtBu)2PN(H)tBu)2}{Cu2(μ-I)2}2]n
(12). Compound 12 was synthesized by a procedure similar to that
of 7 using cuprous iodide (0.106 g, 0.559 mmol) and 1 (0.092 g, 0.139
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mmol. Yield: 86% (0.171 g). Mp: 236−240 °C. Anal. Calcd for
the Louisiana Board of Regents for the purchase of the CCD
diffractometer and the Chemistry Department of Tulane
University for support of the X-ray laboratory.
C36H69Cu4I4N9O2P4: C, 27.97; H, 4.49; N, 8.15. Found: C, 27.62; H,
1
3
4.34; N, 8.01. H NMR (400 MHz, DMSO-d6): δ 7.36 (t, JHH = 7.2
Hz, ArH, 1H), 7.16 (br, s, ArH, 1H), 6.85 (br, s, ArH, 2H), 4.85 (br, s,
NH, 1H), 4.46 (br, s, NH, 1H), 1.50 (s, tBu, 36H), 1.38 (s, tBu, 18H).
31P{1H} NMR (162 MHz, DMSO-d6): δ 106.5 (br, s), 79.0 (br, s),
67.3 (br, s).
REFERENCES
■
(1) (a) Balakrishna, M. S.; Eisler, D. J.; Chivers, T. Chem. Soc. Rev.
2007, 36, 650−664. (b) Briand, G. G.; Chivers, T.; Krahn, M. Coord.
Chem. Rev. 2002, 233/234, 237−254. (c) Stahl, L. Coord. Chem. Rev.
2000, 210, 203−250. (d) Balakrishna, M. S.; Reddy, V. S.;
Krishnamurthy, S. S.; Nixon, J. F.; Laurent, J. C. T. R. B. S. Coord.
Chem. Rev. 1994, 129, 1−90.
X-ray Crystallography. Crystals of each of the compounds 1, 2a,
2b, 4, 7−9, and 12 suitable for X-ray crystal analysis were mounted on
a Cryoloop with a drop of Paratone oil and placed in the cold nitrogen
stream of the Kryoflex attachment of the Bruker APEX CCD
diffractometer. A full sphere of data was collected using 606 scans in ω
(0.3° per scan) at φ = 0, 120, and 240° using the SMART29 software
package, or the APEX230 program suite. The raw data were reduced to
F2 values using the SAINT+ software,31 and a global refinement of unit
cell parameters using about 4575−20067 reflections chosen from the
full data set were performed. Multiple measurements of equivalent
reflections provided the basis for an empirical absorption correction as
well as a correction for any crystal deterioration during the data
collection (SADABS32). The structures 1, 2a, 2b, 4, 7−9, and 12 were
solved by the Patterson method, while the remaining structures were
solved by direct methods and refined by full-matrix least-squares
procedures using the SHELXTL program package.33 Multiple
measurements of equivalent reflections provided the basis for empirical
absorption corrections as well as corrections for any crystal
deterioration during the data collection (SADABS). The structures
were solved by direct methods or the positions of the heavy atoms
were obtained from a sharpened Patterson function. Hydrogen atoms
attached to carbon were placed in calculated positions and included as
riding contributions with isotropic displacement parameters tied to
those of the attached non-hydrogen atoms. Those attached to nitrogen
were placed in locations derived from a difference map and also
included as riding contributions as for the others. The isotropic
thermal parameters of the hydrogen atoms were fixed at 1.2 times that
of the corresponding carbon for phenyl hydrogen and 1.5 times for
C(CH3)3. In the final refinement, the hydrogen atoms were riding with
the carbon atom to which they were bonded.
(2) (a) Garcia, F.; Kowenicki, R. A.; Kuzu, I.; Riera, L.; McPartlin,
M.; Wright, D. S. Dalton Trans. 2004, 2904−2909. (b) Chakravarty,
M.; Kommana, P.; Kumara Swamy, K. C. Chem. Commun. 2005,
5396−5398. (c) Dodds, F.; Garcia, F.; Kowenicki, R. A.; McPartlin,
M.; Steiner, A.; Wright, D. S. Chem. Commun. 2005, 3733−3735.
(d) Balakrishna, M. S.; Mague, J. T. Organometallics 2007, 26, 4677−
4679. (e) Kommana, P.; Kumara Swamy, K. C. Inorg. Chem. 2000, 39,
4384−4385.
(3) Kumar, S. N.; Kumar, P. K.; Kumar, P. K. V. P.; Kommana, P.;
Vittal, J. J.; Kumara Swamy, K. C. J. Org. Chem. 2004, 69, 1880−1889.
(4) Balakrishna, M. S.; Suresh, D.; Mague, J. T. Inorg. Chim. Acta
2011, 372, 259−265.
(5) (a) Balakrishna, M. S.; Suresh, D.; Rai, A.; Mague, J. T.; Panda, D.
Inorg. Chem. 2010, 49, 8790−8801. (b) Suresh, D.; Balakrishna, M. S.;
Rathinasamy, K.; Panda, D.; Mobin, S. M. Dalton Trans. 2008, 2812−
2814.
(6) (a) Chandrasekaran, P.; Mague, J. T.; Balakrishna, M. S. Dalton
Trans. 2009, 5478−5486. (b) Chandrasekaran, P.; Mague, J. T.;
Balakrishna, M. S. Organometallics 2005, 24, 3780−3783. (c) Suresh,
D.; Balakrishna, M. S.; Mague, J. T. Dalton Trans. 2008, 3272−3274.
(7) (a) Chandrasekaran, P.; Mague, J. T.; Balakrishna, M. S. Inorg.
Chem. 2006, 45, 6678−6683. (b) Chandrasekaran, P.; Mague, J. T.;
Balakrishna, M. S. Dalton Trans. 2007, 2957−2962.
(8) (a) Alyea, E. C.; Ferguson, G.; Malito, J.; Ruhl, B. L. Inorg. Chem.
1985, 24, 3719−3720. (b) Barron, P. F.; Dyason, J. C.; Healy, P. C.;
Engelhardt, L. M.; Pakawatchai, C.; Patrick, V. A.; White, A. H. J.
Chem. Soc., Dalton Trans. 1987, 1099−1106. (c) Graham, P. M.; Pike,
R. D.; Sabat, M.; Bailey, R. D.; Pennington, W. T. Inorg. Chem. 2000,
39, 5121−5132. (d) Churchill, M. R.; Rotella, R. J. Inorg. Chem. 1979,
18, 166−171.
(9) (a) Barron, P. F.; Dyason, J. C.; Engelhardt, L. M.; Healy, P. C.;
White, A. H. Inorg. Chem. 1984, 23, 3766−3769. (b) Ganesamoorthy,
C.; Mague, J. T.; Balakrishna, M. S. Eur. J. Inorg. Chem. 2008, 596−
604.
(10) (a) Ganesamoorthy, C.; Balakrishna, M. S.; George, P. P.;
Mague, J. T. Inorg. Chem. 2007, 47, 848−858. (b) Fu, W.-F.; Gan, X.;
Che, C.-M.; Cao, Q.-Y.; Zhou, Z.-Y.; Zhu, N. N.-Y. Chem.Eur. J.
2004, 10, 2228−2236. (c) Araki, H.; Tsuge, K.; Sasaki, Y.; Ishizaka, S.;
Kitamura, N. Inorg. Chem. 2005, 44, 9667−9675.
(11) (a) Liu, Z.; Djurovich, P. I.; Whited, M. T.; Thompson, M. E.
Inorg. Chem. 2012, 51, 230−236. (b) Zink, D. M.; Grab, T.; Baumann,
T.; Nieger, M.; Barnes, E. C.; Klopper, W.; Brase, S. Organometallics
2011, 30, 3275−3283. (c) Chakrabarty, R.; Mukherjee, P. S.; Stang, P.
J. Chem. Rev. 2011, 111, 6810−6918.
In the structures of 8, 9, and 12, the tert-butyl groups on exocyclic
nitrogen and bridged iodine in 12 were disordered with the atoms
statistically distributed over the two atomic positions. In all these
structures, the two atoms were not constrained to locate in the same
position, but the anisotropic thermal parameters were restricted to be
equal. The details of X-ray structural determinations are given in
Tables 1.
ASSOCIATED CONTENT
* Supporting Information
■
S
X-ray crystallographic files in CIF format for the structure
determinations of 1, 2a, 2b, 4, 7−9, and 12; further details are
given in Chart S1 and structures showing hydrogen bonding.
This material is available free of charge via the Internet at
http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
*E-mail: krishna@chem.iitb.ac.in or msb_krishna@iitb.ac.in.
Fax: +91-22-5172-3480/2576-7152.
■
(12) (a) Balakrishna, M. S. J. Organomet. Chem. 2010, 695, 925−936.
(b) Balakrishna, M. S.; Chandrasekaran, P.; Venkateswaran, R. J.
Organomet. Chem. 2007, 692, 2642−2648.
(13) Balakrishna, M. S.; Venkateswaran, R.; Mague, J. T. Inorg. Chem.
2009, 48, 1398−1406.
(14) (a) Vijjulatha, M.; Kumaraswamy, S.; Kumara Swamy, K. C.;
Engelhardt, U. Polyhedron 1999, 18, 2557−2562. (b) Kumaravel, S. S.;
Krishnamurthy, S. S.; Cameron, T. S.; Linden, A. Inorg. Chem. 1988,
27, 4546−4550. (c) Garcia, F.; Goodman, J. M.; Kowenicki, R. A.;
McPartlin, M.; Riera, L.; Silva, M. ı. A.; Wirsing, A.; Wright, D. S.
Dalton Trans. 2005, 1764−1773. (d) Calera, S. G.; Wright, D. S.
Dalton Trans. 2010, 39, 5055−5065.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We are grateful to the Department of Science and Technology
(DST), New Delhi, for financial support of this work through
Grant SR/S1/IC-17/2010. G.S.A. thanks CSIR, New Delhi, for
a Research Fellowship (JRF & SRF). We also thank the
Department of Chemistry Instrumentation Facilities, IIT
Bombay, for spectral and analytical data and J.T.M. thanks
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Article
(15) Chandrasekaran, P.; Mague, J. T.; Balakrishna, M. S. Inorg.
Chem. 2006, 45, 5893−5897.
(16) Colquhoun, I. J.; Christina, H.; McFarlane, E.; McFarlane, W.;
Nash, J. A.; Keat, R.; Rycroft, D. S.; Thompson, D. G. Org. Magn.
Reson. 1979, 12, 473−475.
(17) (a) Lief, G. R.; Moser, D. F.; Stahl, L.; Staples, R. J. J.
Organomet. Chem. 2004, 689, 1110−1121. (b) Suresh, D.; Balakrishna,
M. S.; Mague, J. T. 2007, 48, 2283−2285.
(18) Balakrishna, M. S.; Venkateswaran, R.; Mague, J. T. Dalton
Trans. 2010, 39, 11149−11162.
(19) Calera, S. G.; Eisler, D. J.; Goodman, J. M.; McPartlin, M.;
Singh, S.; Wright, D. S. Dalton Trans. 2009, 1293−1296.
(20) Bowmaker, G. A.; Boyd, S. E.; Hanna, J. V.; Hart, R. D.; Healy,
P. C.; Skelton, B. W.; White, A. H. J. Chem. Soc., Dalton Trans. 2002,
2722−2730.
(21) Bowmaker, G. A.; Dyason, J. C.; Healy, P. C.; Engelhardt, L. M.;
Pakawatchai, C.; White, A. H. J. Chem. Soc., Dalton Trans. 1987, 1089−
1097.
(22) Hanna, J. V.; Hart, R. D.; Healy, P. C.; Skelton, B. W.; White, A.
H. J. Chem. Soc., Dalton Trans. 1998, 2321−2325.
(23) Effendy; Nicola, C. D.; Fianchini, M.; Pettinari, C.; Skelton, B.
W.; Somers, N.; White, A. H. Inorg. Chim. Acta 2005, 358, 763−795.
(24) Armarego, W. L.; Perrin, D. D. Purification of Laboratory
Chemicals, 4th ed.; Butterworth-Heinemann Linacre House: Jordan
Hill, Oxford, U. K., 1996.
(25) Bashall, A.; Doyle, E. L.; Tubb, C.; Kidd, S. J.; McPartlin, M.;
Woods, A. D.; Wright, D. S. Chem. Commun. 2001, 2542−2543.
(26) Brandys, M.; Jennings, M. C.; Puddephatt, R. J. J. Chem. Soc.,
Dalton Trans. 2000, 4601−4606.
(27) Tatsuno, Y.; Yoshida, T.; Otsuka, S. Inorg. Synth. 1990, 28, 342−
343.
(28) Furniss, B. S.; Hannaford, A. J.; Smith, P. W. G.; Tatchell, A. R.
Vogel’s Textbook of Practical Organic Chemistry, 5th ed.; ELBS: London,
England, 1989; pp 428−429.
(29) SMART, Version 5.625; Bruker-AXS: Madison, WI, 2000.
(30) APEX2, version 2.1-0; Bruker-AXS: Madison, WI, 2006.
(31) SAINT+, Version 7.03; Bruker-AXS: Madison, WI, 2006.
(32) Sheldrick, G. W. SADABS, versions 2.05 and 2007/2; University
of Gottingen: Gottingen, Germany, 2002.
̈
̈
(33) SHELXTL, Version 6.10; Bruker-AXS: Madison, WI, 2000.
5930
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