Design and synthesis of binucleating macrocyclic clefts derived from schiff-base calixpyrroles

FULL PAPER

DOI: 10.1002/chem.200600989

Design and Synthesis of Binucleating Macrocyclic Clefts Derived from Schiff-

Base Calixpyrroles

Gonzalo Givaja,^[a]Manuel Volpe,^[a]James W. Leeland,^[a]Michael A. Edwards,^[a]

Thomas K. Young,^[a]S. Barnie Darby,^[a]Stuart D. Reid,^[a]AlexanderJ. Blake, ^[a]

Claire Wilson,^[a]Joanna Wolowska,^[b]Eric J. L. McInnes,^[b]Martin Schrçder,^[a]and

Jason B. Love*^[a]

Abstract: The syntheses, characterisa-

tion and complexation reactions of a

series of binucleating Schiff-base calix-

pyrrole macrocycles are described. The

acid-templated [2+2] condensations be-

tween meso-disubstituted diformyldi-

pyrromethanes and o-phenylenedi-

to L³) complexes. All of these com-

plexes have been structurally character-

ised in the solid state and are found to

adopt wedged structures that are en-

forced by the rigidity of the aryl back-

bone to give a cleft reminiscent of the

structures of Pacman porphyrins. The

at the pyrrolic nitrogen atoms, and the

Ni^IIcations are therefore co-ordinated

by the imine nitrogen atoms only to

give an open conformation for the

complex. The dicopper complex

[Cu₂(L³)] was crystallised in the pres-

ence of pyridine to form the adduct

[Cu₂(py)(L³)], in which, in the solid

state, the pyridine ligand is bound

within the binuclear molecular cleft.

Reaction between H₄L¹and [Mn-

A

binuclear nickel complexes [Ni

OMe)₂Cl₂(HOMe)₂

(H₄L¹)] and [Ni₂

OH)₂Cl₂(HOMe)

(H₄L⁵)] have also

ACHTREUNG

ic macrocycles H₄L¹to H₄L⁶upon basic

workup. The single-crystal X-ray struc-

tures of both H₄L³·2EtOH and

H₄L⁶·H₂O confirm that [2+2] cyclisa-

tion has occurred, with either EtOH or

H₂O hydrogen-bonded within the mac-

rocyclic cleft. A series of complexation

reactions generate the dipalladium

[Pd₂(L)] (L=L¹to L⁵), dinickel

[Ni₂(L¹)] and dicopper [Cu₂(L)] (L=L¹

A

N

ACHTREUNG

A

ACHTREUNG

been prepared, although in these cases

the solid-state structures show that the

macrocyclic ligand remains protonated

A

N

mation of the dimanganese complex

[Mn₂(L¹)], which, upon crystallisation,

formed the mixed-valent complex

Keywords: EPR spectroscopy

·

[Mn

₂(m-OH)(L¹)] in which the hydroxo

G

macrocyclic ligands · metallation ·

N ligands · transition metals

ligand bridges the metal centres within

the molecular cleft.

Introduction

While the physical properties and reactivity patterns of

mononuclear transition metal complexes are controlled pre-

cisely by using design features intrinsic to the supporting

ligand set, the inclusion of more than one metal centre in-

troduces additional synthetic challenges, as both the local

co-ordination spheres and respective locations of the metal

centres must be defined. Moreover, important chemical

transformations, such as alkane oxygenation,^[1]oxygen re-

duction,^[2,3]redox reactions involving hydrogen,^[4]and nitro-

gen fixation,^[5]are efficiently mediated by metalloenzymes

that contain bi- or multimetallic reactive sites that are pre-

cisely organised by attendant ligands and an associated pro-

tein envelope.^[6]Thus, the design and exploitation of ligands

that can promote the construction of bi- and multimetallic

complexes that imitate or surpass enzymes as catalysts in

[a] Dr. G. Givaja, Dr. M. Volpe, J. W. Leeland, M. A. Edwards,

T. K. Young, S. B. Darby, S. D. Reid, Dr. A. J. Blake, Dr. C. Wilson,

Prof. M. Schrçder, Dr. J. B. Love

School of Chemistry

University of Nottingham

University Park

Nottingham, NG72RD (UK)

Fax : (+44)115-951-3563

E-mail: jason.love@nottingham.ac.uk

[b] Dr. J. Wolowska, Dr. E. J. L. McInnes

EPSRC Multi-frequency EPR Service

School of Chemistry, University of Manchester

Oxford Road, Manchester, M139PL (UK)

Supporting information for this article is available on the WWW

under http://www.chemeurj.org/ or from the author.

Chem. Eur. J. 2007, 13, 3707 – 3723

ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

3707

such processes have both a long-held fascination and strate-

gic significance.^[7]This design strategy is exemplified by the

synthesis and chemistry of cofacial diporphyrin complexes,

in which the well-known co-ordinative properties of the por-

phyrin are combined with exceptional control of the inter-

metallic separation by a rigid and well-defined spacer be-

tween the two porphyrinic compartments (see Scheme 1).^[8,9]

the resultant bimetallic complexes. Condensation reactions

between 2,2’-5,5’-diformyldipyrromethenes and aliphatic di-

A

accordion diporphyrins in which the two N₄-iminopyrrole

donor compartments are separated by an alkyl linker

(Scheme 1).^[19–21]However, the flexibility of this linking

chain results in bimetallic complexes in which the relative

positions of the metal centres are not well defined; even so,

such dimanganese complexes do act as catalysts for the re-

duction of peroxide.^[19]Alternatively, [2+2] Schiff-base calix-

pyrroles formed from the condensation of 2,2’-5,5’-diformyl-

bipyrroles with o-diaminobenzenes generate bimetallic com-

plexes similar to those of expanded porphyrins in which

more rigid and flattened structures are adopted due to more

extensive p conjugation (Scheme 1).^[20]

Using standard Vilsmeier–Haack formylation procedures,

we^[22]and others^[23]have recently developed synthetic path-

ways to the 2,2’-5,5’-diformyldipyrromethanes

i and ii

(Scheme 2). We have shown that these synthons react with

primary amines to form new acyclic iminopyrrole ligands

that support the formation of binuclear [4+4] double heli-

cates of Mn^II, Fe^IIand Co^IIthat display asymmetric, binu-

clear cleft motifs in the solid state.^[24,25]It was clear to us

that condensation of i or ii with o-diaminobenzenes should

result in the formation of [2+2] Schiff-base calixpyrroles

(Scheme 2), and that these macrocycles would afford binu-

clear transition metal complexes. Furthermore, we reasoned

that the combination of the two N₄-iminopyrrole donor

compartments linked by rigid aryl spacers should result in

complexes of well-defined structure. We report herein the

syntheses and characterisation of a series of Schiff-base cal-

ixpyrrole macrocycles H₄L, which form binuclear complexes

that adopt molecular cleft structures similar to those of cofa-

cial or Pacman diporphyrins; some of this work has been

previously communicated.^[26]Sessler and co-workers have

reported independently routes to the Schiff-base calixpyr-

role H₄L¹and its analogues and have shown that binuclear

Scheme 1. Examples of binuclear transition metal complexes of cofacial

diporphyrins and Schiff-base expanded porphyrin macrocycles.^[20,45,61]

The resultant bimetallic molecular cleft facilitates exten-

sive stoichiometric and catalytic small-molecule chemistry,

such as oxygen redox and atom-transfer reactions,^[3,10]hydro-

gen activation,^[11,12]nitrogen reduction^[13]and alkane activa-

tion.^[11,14]Furthermore, it is possible to vary the two cofacial

donor compartments to form porphyrin-corroles and bis-

(corrole) binuclear complexes; these compounds also cata-

lyse oxygen reduction.^[15,16]Other classes of polypyrrolic li-

gands, such as expanded porphyrins, have also been exploit-

ed in the formation of binuclear complexes, and, in contrast

to cofacial diporphyrins, generally result in metal com-

pounds that have flattened structures due to extensive p

conjugation of the porphyrinic macrocycle.^[17]

In an effort to provide more co-ordinative flexibility and

modularity of design, and also to surmount the sometimes

arduous synthetic routes to cofacial and expanded porphy-

Fe^III₂(m-O), Cu^I₂and Cu^IImotifs can be supported by this

2

A

ligand.^[27–29]Furthermore, Brooker and co-workers have ex-

ploited dipyrromethane synthon i for the metal-templated

syntheses of macrocycles analogous to H₄L. These iono-

phores incorporate flexible alkyl-chain spacers between the

N₄-donor compartments, and their binuclear complexes

therefore adopt flattened structures similar to accordion di-

porphyrins.^[30]

phyrin analogues as binucleating ligands for transition

metals.^[18]Significantly, this class of macrocyclic ligand com-

bines the desired co-ordinative features of the pyrrole group

with the exceptional design characteristics and synthetic ver-

satility of Schiff-base condensation procedures that can

assist in ligand synthesis and engender structural control in

Scheme 2. Synthesis of the Schiff-base calixpyrrole macrocycles H₄L¹–H₄L⁶(L¹to L⁵, HX=HOTs; L⁶, HX=HO₂CCF₃).

3708

www.chemeurj.org

ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Chem. Eur. J. 2007, 13, 3707 – 3723

Binucleating Macrocyclic Clefts

FULL PAPER

Table 1. Selected bond lengths [] and angles [8] for H₄L³·2EtOH and

H₄L⁶·H₂O.

Results and Discussion

H₄L ·

A

H₄L ·

⁶(H₂O)

G

Ligand synthesis and structure: meso-Disubstituted difor-

myldipyrromethanes i and ii react with aromatic o-disubsti-

tuted diamines in MeOH in the presence of TsOH to gener-

ate the orange and crystalline [2+2] macrocyclic products

ꢀ

N1 C1

1.2824(17)

1.4091(17)

–

1.289(3)

–

ꢀ

N1 C46

ꢀ

N1 C26A

1.413(3)

1.433(3)

1.371(3)

1.375(3)

1.370(3)

1.400(3)

1.383(3)

–

ꢀ

C1 C2

1.4313(19)

1.3729(19)

1.3752(17)

1.3602(16)

1.405(2)

1.3739(19)

120.66(13)

–

H₄L

¹(TsOH)₄in good yield (Scheme 2). The use of acid as a

A

ꢀ

C2 C3

template in these reactions is the key, and, as described in-

dependently by Sessler and co-workers, a variety of acids

can mediate this [2+2] cyclisation reaction.^[29]

ꢀ

N2 C2

ꢀ

N2 C5

ꢀ

C3 C4

ꢀ

C4 C5

The ¹H NMR spectrum of H₄L¹(TsOH)₄shows a single

R

C1-N1-C46

resonance characteristic of imine formation at d=8.53ppm

plus AB doublets at d=7.32 and 7.01 ppm that integrate as

four arylsulfonic acid groups per macrocycle, that is, each

imine nitrogen atom is protonated, in contrast to the synthe-

C1-N1-C26A

121.0(3)

The Schiff-base calixpyrrole adopts a non-linear, bowl-

like conformation around a hydrogen-bonded molecule of

EtOH, but the second molecule of EtOH does not interact

with the macrocyclic ligand. The presence of co-ordinated

EtOH within the macrocyclic cavity illustrates the capacity

of H₄L³to act both as a hydrogen-bond donor, through in-

teractions between pyrrole NH protons and the ethanolic

oxygen atom (N2···O1 2.992, N7···O1 2.960 ), and as a hy-

drogen-bond acceptor, through interactions between the

imine N atoms and the ethanolic OH proton (N8···O1 2.990,

N1···O1 3.001 ). These hydrogen-bonding interactions are

commensurate with the development of similar Schiff-base

calixpyrroles and acyclic iminopyrrole compounds as effec-

tive anion-binding agents.^[31]The non-linear structure adopt-

ed by H₄L³is unlike that seen for related expanded porphy-

sis of H₄L

¹(HCl)₂, in which the macrocycle is doubly proton-

R

ated.^[29]Treatment of these acid salts with a base such as

NaOH or Et₃N in alcoholic solvents quantitatively precipi-

tates the acid-free macrocycles H₄L (L=L¹–L⁶), which can

be isolated simply by suction filtration. These yellow, air-

stable, amorphous materials are poorly soluble in common

organic solvents unless additional protic solvent is present;

presumably, in the absence of protic solvents, these macro-

cycles form hydrogen-bonded aggregates in the solid state.

1

The H NMR spectrum of H₄L¹in a mixture of CDCl₃and

[D₄]methanol confirms the absence of the tosylate anion

and retention of the imine group, associated with a singlet

resonance at d=8.07 ppm; no resonances due to the pyrrolic

NH groups are observed due to rapid exchange with the

protic solvent. While neutralisation reactions in methanolic

solution result in amorphous powders, we discovered that

yellow, crystalline macrocycles H₄L·nEtOH are deposited

from hot ethanol. The solid-state structure of H₄L³·2EtOH,

the macrocycle derived from 1,2-diaminonaphthalene and i,

was determined, and is shown in Figure 1; selected bond

lengths and angles are listed in Table 1. The crystal structure

of H₄L³·2EtOH confirms that [2+2] cyclisation has taken

place, and that a neutral macrocycle is formed on addition

of Et₃N to the acid salt.

rins and Schiff-base porphyrin analogues, and is a conse-

quence of both conformational flexibility and the lack of ex-

tended p conjugation that results from the incorporation of

sp³-hybridised meso-CMe₂groups into the macrocyclic

framework. It is clear from the solid-state structure of H₄L³

that the meso-CMe₂groups can act as a hinge that effective-

ly compartmentalises two N₄-donor sets.

We have also determined the X-ray crystal structure of

H₄L⁶, a macrocycle that incorporates bulky meso-tetra-

methylcyclohexyl substituents (see Figure 1, Table 1). In a simi-

lar manner to H₄L³, this macrocycle

adopts a wedge-shaped conformation

due to hydrogen-bonding donor and ac-

ceptor interactions between pyrrole

and imine nitrogen atoms and a mole-

cule of water (O1W···N1 3.127,

O1W···N2 3.109, O1W···N3 3.197,

O1W···N4 3.243 ). However, unlike in

H₄L³, this introduces a hinge into the

macrocycle at the o-aryl groups, which

results in the formation of a hinged cleft

structural motif. Thus, two distinctly

different structural motifs are formed

by this ligand framework, and are

therefore expected to result in different

metal-binding N₄-donor compartments.

The structure of H₄L³was examined

in solution by variable-temperature

Figure 1. Solid-state structures of a) H₄L³·2EtOH and b) H₄L⁶·H₂O. For clarity, all hydrogen atoms,

except those involved in hydrogen bonding, and solvent molecules have been removed for clarity

(50% probability displacement ellipsoids).

Chem. Eur. J. 2007, 13, 3707 – 3723

ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.chemeurj.org

3709

J. B. Love et al.

¹H NMR spectroscopy, with and without added

[D₄]methanol solvent (see Supporting Information). Similar-

ly large cyclopolypyrroles, such as cycloocta- and cyclodode-

capyrrole, exhibit dynamic behaviour in solution; on cooling

1

to low temperature, the H NMR spectra of these macrocy-

cles correlate well to their “looped” solid-state structures.^[32]

Cooling a solution of anhydrous H₄L³in [D₈]THF to 183K

results in no significant change to the ¹H NMR spectrum,

other than line broadening at low temperatures. However,

the addition of a small amount of [D₄]methanol to the

1

sample caused the H NMR resonances to sharpen consider-

ably at room temperature and, between 233 and 203 K, re-

sults in broadening of the resonance associated with the

meso-CH₃protons and its decoalescence into two new sig-

nals that overlap considerably with the resonance of residual

THF at d=1.73ppm; the remaining ligand resonances

remain unaffected. This dynamic behaviour is consistent

with the adoption of a hinged, C₂-symmetric macrocyclic

conformation at low temperature in which the meso-methyl

groups are oriented endo and exo to a macrocyclic cleft, and

is presumably promoted by hydrogen-bonding interactions

with the protic solvent, as observed in the structures of

H₄L³·2EtOH and H₄L⁶·H₂O (see above). Indeed, this solu-

tion structure correlates to both of the wedged solid-state

structures of H₄L³and H₄L⁶if, in the former structure, it is

assumed that the hydrogen-bonded EtOH molecule can

shuttle between the two N₄compartments at low tempera-

ture. Whereas this organisation of the ligand framework into

a predefined, wedged conformation in protic solvents is ob-

served only at low temperature, the predisposition for such

an organised ligand structure in solution may well influence

the formation and structural behaviour of the metal com-

plexes of L.

Scheme 3. Synthesis of transition metal complexes of L. Conditions:

i) Pd

KH; b) [NiCl₂

(thf)₂{N(SiMe₃)₂}₂] PhMe, D.

ACHTREUNG

N

ACHTREUNG

G

ACHTREUNG

mass spectra of the reaction mixtures show the molecular

ions [Pd₂(L)]⁺with appropriate isotopic patterns and are

consistent with the sole formation of the Pd^IIcomplexes; el-

emental analyses also support the proposed molecular for-

mula and indicate that the five dimetallic complexes are

neutral with no counterions. The absorptions at 1557 and

1561 cm^ꢀ1observed for [Pd₂(L¹)] and [Pd₂(L³)] in their re-

spective IR spectra are attributable to imine/pyrrole n(C=N)

G

stretching vibrations. The electronic spectrum of [Pd₂(L¹)] in

CHCl₃shows intense absorptions at l=311 (lge=4.56), 414

(lge=4.35) and 433 nm (lge=4.35), similar to the diagnostic

Soret and Q-bands observed in the electronic spectra of por-

phyrinic complexes, albeit of reduced intensity and blue-

shifted.

Palladium complexes: The reactions between Pd

C

Structural characterisation of [Pd₂(L)]: Crystals suitable for

X-ray diffraction were obtained for the dipalladium com-

plexes, and their structures determined; selected bond

lengths and angles are listed in Table 2. The overall structur-

Table 2. Selected bond lengths [] and angles [8] for [Pd₂(L)] (L=L², L³, L⁵), [Ni₂(L¹)], [Cu₂(L)] (L=L¹, L², L³) and [Cu₂

[Pd₂(L²)] [Pd₂(L³)] [Pd₂(L⁵)] [Ni₂(L¹)] [Cu₂(L¹)] [Cu₂(L²)]

ACHTREUNG

A

G

R

N

G

E

ACHTREUNG

ꢀ

M1 N1

2.068(4)

1.935(4)

1.928(4)

2.059(4)

2.051(4)

1.947(4)

1.935(4)

2.075(4)

2.049(2)

1.937(2)

1.934(2)

2.096(2)

2.049(2)

1.937(2)

2.078(2)

2.068(8)

1.920(10)

1.935(9)

2.058(10)

2.060(10)

1.945(9)

1.928(10)

2.081(9)

1.938(2)

1.827(2)

1.814(2)

1.921(2)

2.004(4)

1.915(3)

1.893(4)

2.045(3)

1.987(2)

1.919(2)

1.903(2)

2.073(3)

1.990(2)

1.911(2)

1.891(3)

2.039(2)

1.996(2)

1.915(2)

1.897(2)

2.050(2)

1.987(2)

1.920(2)

1.903(2)

2.084(2)

2.067(3)

1.948(3)

1.933(3)

2.090(3)

2.008(3)

1.906(3)

1.904(3)

2.012(3)

2.258(3)

2.983

ꢀ

M1 N2

ꢀ

M1 N3

ꢀ

M1 N4

ꢀ

M2 N5

ꢀ

M2 N6

ꢀ

M2 N7

ꢀ

M2 N8

ꢀ

M1 N9

ꢀ

M2 N9

N1-M1-N2

N2-M1-N388.4(2)

N3-M1-N4

N1-M1-N4

N5-M2-N6

N6-M2-N7

N7-M2-N8

N8-M1-N5

80.32(19)

88.18(9)

80.03(17)

111.27(17)

80.26(17)

88.01(17)

80.43(17)

111.29(16)

79.94(9)

88.2(4)

80.68(9)

110.99(8)

79.96(9)

88.26(9)

80.65(9)

110.93(8)

80.2(4)

83.67(10)

81.98(15)

81.54(10)

86.41(10)

82.84(10)

109.49(10)

81.65(10)

87.41(11)

82.61(10)

108.13(10)

81.39(10)

81.08(12)

88.40(10)

86.52(15)

83.21(10)

104.95(10)

86.51(11)

82.48(15)

109.00(14)

) 84.80(13

81.4(4)

110.3(4)

80.4(4)

88.4(4)

81.3(4)

109.9(4)

82.36(10)

109.72(9)

81.44(10)

87.50(10)

82.11(10)

108.66(9)

81.21(12)

106.13(12)

82.59(13)

85.72(13)

82.82(12)

108.55(12)

99.08

ꢀ

M1 N9···M2

3710

www.chemeurj.org

ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Chem. Eur. J. 2007, 13, 3707 – 3723

Binucleating Macrocyclic Clefts

FULL PAPER

al characteristics of these compounds are similar, so only

[Pd₂(L³)] will be discussed in detail; the X-ray crystal struc-

tures of [Pd₂(L¹)] and [Pd₂(L⁴)] have been reported previ-

ously by us.^[26]

(M···M) and the “bite” (q) and torsional twist (F) angles be-

tween the two MN₄compartments (see Figure 3); these

have been determined for all of the structurally character-

ised complexes described here and are detailed in Table 3.

In [Pd₂(L³)] (Figure 2), each Pd^IIcation is bound to two

deprotonated pyrrole nitrogen atoms of one dipyrromethane

unit and to the two adjoining imine nitrogen donor atoms in

an N₄co-ordination sphere. The metal centres adopt square-

planar geometries (sum of angles at Pd1 359.79, Pd2

359.808), in which Pd1 is located 0.048 out of the mean

plane (o.o.p) defined by the N₄donor atoms, whereas Pd2 is

ꢀ

0.071 o.o.p. Two distinct sets of Pd N bond lengths are

observed, shorter (av 1.936 ) to the pyrrolic nitrogen

atoms (N2 N3, N6, N7) and longer (av 2.068 ) to the four

imine nitrogen atoms (N1, N4, N5, N8). The N-Pd-N angles

range from 79.94(9) to 110.989(8)8, the smallest angle being

defined by the pyrrole-imine chelate and the largest involv-

ing both imine nitrogen atoms. The presence of the sp³-hy-

bridised meso-CMe₂link between the planar imine-pyrrole

chelates not only limits electronic conjugation of the macro-

cycle, but also introduces a degree of flexibility within the

complex. Thus, the imine-pyrrole chelates are not coplanar,

and display dihedral angles between Pd1N₄and Pd2N₄com-

partments of 11.0 and 19.78, respectively. Importantly, the

metal–ligand geometry, together with the presence of the

rigid o-aryl spacers between the two PdN₄-donor compart-

ments, has a significant impact on the overall molecular

shape of [Pd₂(L³)]. This results in a dimetallic molecular

cleft structure in which the o-aryl units are offset, face-to-

face p-stacked (intrastack distance 3.604 , offset angle

238)^[33]and act as hinges that promote a wedgelike arrange-

ment of the two PdN₄square planes. This gross structural

motif is similar to those observed for single-pillared or

Pacman diporphyrin complexes,^[9]in which the spatial sepa-

ration between two metal porphyrins is rigidly defined by an

appropriate, generally aromatic, spacer unit. The structure

of [Pd₂(L³)] can be compared to those of similar molecules

by defining three variables: the metal–metal separation

Figure 3. Schematic showing the definition of the bite angle q (q=M-C-

M angle, C=bisector of the vector between the aryl ring centroids) and

torsional twist F (F=normal dihedral angle of MN₄and aryl C₆plane).

The effect of varying the substituents at the meso-carbon

atom or at the 3,4-positions of the o-aryl hinge can be ana-

lysed by comparing the structures of the dipalladium com-

plexes [Pd₂(L)]. The Pd···Pd separation varies between 3.544

and 4.120 , and, in contrast to Pacman diporphyrinic ana-

logues in which the M···M separation can vary between 3.5

and 7.8 (this range is dependant on the nature of the

spacer in the Pacman ligand),^[34]represents a small and rig-

idly constrained vertical translation. Furthermore, the X-ray

crystal structures of the dipalladium Pacman bis-porphyrin

complexes [Pd

N

DPD are dibenzoxanthene and dibenzofuran pillars, respec-

tively, show cofacial arrangements of the porphyrins [bite

angles: 3.9 (DPX) and 11.08 (DPD); torsional twists: 14.6

(DPX) and 3.58 (DPD)], with considerably different Pd···Pd

separations [3.97 (DPX) and 6.81 (DPD)].^[35]The palladi-

um complexes [Pd₂(L)] can also be compared to Pacman di-

porphyrins that were synthesised by Naruta and co-workers,

in which the two porphyrins are linked by a similar o-phen-

ylene spacer.^[36–38]In contrast

to [Pd₂(L)], meso-mesityl-sub-

stituted dicobalt complexes of

these ligands adopt wedged-

geometries with large interme-

tallic

separations

(e.g.,

6.570(2) ),^[37]while dizinc an-

alogues are truly cofacial and

display short interplanar sepa-

rations (3.43 ) due to favour-

able p-stacking interactions.^[39]

The intermetallic separation in

the [Pd₂(L)] complexes ap-

pears to be intrinsically linked

to both the bite and twist

angles, which are dependant

on ligand substitution patterns.

Better offset, face-to-face p-

stacking overlap of the hinge

Figure 2. Solid-state structure of [Pd₂(L³)] (50% displacement ellipsoids). For clarity, solvent molecules and all

hydrogen atoms are omitted.

Chem. Eur. J. 2007, 13, 3707 – 3723

ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.chemeurj.org

3711

J. B. Love et al.

Table 3. Comparison of the geometric data of Pd, Ni, Cu, Mn and Fe

Pacman complexes of L.

Nickel complexes: The reactions between hydrated NiCl₂

and H₄L (L=L¹and L⁵) in the presence of Et₃N do not

result in the expected binuclear complexes [Ni₂(L)], but

Compound

[Pd₂(L¹)]

[Pd₂(L²)]

[Pd₂(L³)]

[Pd₂(L⁴)]

[Pd₂(L⁵)]

[Pd₂(DPX)]

[Ni₂(L¹)]

[Ni₂(DPX)]

[Cu₂(L¹)]

[Cu₂(L²)]

[Cu₂(L³)]

[Cu₂

(m-py)(L³)].

[Cu₂(DPX)]

[Mn₂

(m-OH)(L¹)]

[Fe₂

(m-O)(L¹]

Twist [8]^[a]

Bite [8]^[a]

M···M []

Ref.

[26]

G

18.8

11.1

23.0

21.6

28.5

14.6

30.3

22.2

26.2

24.0

20.5

28.3

32.2

19.6

7.4

56.5

62.1

53.0

57.4

59.7

3.9

3.762

rather the methoxy- and hydroxy-bridged adducts [Ni₂

OMe)₂Cl₂(HOMe)₂(m-OH)₂Cl₂(HOMe)-

(H₄L¹)], and [Ni₂

(H₄L⁵)], respectively (Scheme 3). Elemental analytical data

for these orange solids support the proposed molecular for-

mulae, and the IR spectra of [Ni₂(m-OMe)₂Cl₂(HOMe)₂-

(H₄L¹)] and [Ni₂(H₄L⁵)] show bands at

(m-OH)₂Cl₂(HOMe)

1615 and 1617 cm^ꢀ1, respectively, characteristic of n

(C=N)

stretching vibrations. The electrospray mass spectrum of

[Ni₂(m-OMe)₂Cl₂(HOMe)₂

(H₄L¹)] displays a parent ion at

m/z 792 (100) with the correct isotopic pattern for [Ni₂Cl₂-

(H₄L¹)]⁺, while [Ni₂(H₄L⁵)] shows a mo-

(m-OH)₂Cl₂(HOMe)

lecular ion peak at m/z 1024 assigned to the binuclear frag-

(m-

G

4.108/4.120^[b]

3.544

this work

A

G

A

ACHTREUNG

E

this work

AHCTREUNG

[26]

E

3.828

3.944

3.97

3.632

4.689

4.014

3.473

4.053

N

this work

[35]

A

ACHTREUNG

A

G

U

54.9

1.9

this work

A

G

A

ACHTREUNG

[45]

E

G

ACHTREUNG

N

61.0

52.1

62.0

53.4

53.3

59.9

this work

[27][c]

G

[27][c]

A

N

ACHTREUNG

G

E

3.695/3.738^[b]

3.552

4.014

this work

ACHTREUNG

A

G

A

ACHTREUNG

R

A

this work

[45]

T

G

.910 2.33

1

ment [Ni

₂(H₄L⁵)]⁺. The H NMR spectra of both Ni^IIcom-

N

R

U

4.9

0.344.8.145

49.7

3

3.417

this work

[28][c]

plexes are featureless.

H

G

[a] The twist angle was calculated as the dihedral angle between the

backbone C₆aryl and MN₄planes (i.e., 08=no twist), and the bite angle

was determined as the M-X-M angle, where X=bisector of the centroid–

centroid vector of the backbone C6 aryl rings (see Figure 3). [b] Two

molecules in the asymmetric unit. [c] Determined from CIF data deposit-

ed in the Cambridge Structural Database.

Structural characterisation of [Ni

A

(HOMe)₂-

A

(m-OH)₂Cl₂

G

ACHTREUNG

suitable for X-ray crystallography were grown by slow diffu-

sion of diethyl ether into MeOH/CH₂Cl₂solutions, and the

solid-state structures determined (Figure 4); selected bond

lengths and angles are displayed in Table 4.

The X-ray crystal structure of [Ni

N

AHCTREUNG

aryl groups (L³>L¹>L²) causes an increased twist angle

and decreased bite angle, which result in shorter Pd···Pd dis-

tances. The effect of substitution of the meso-CMe₂groups

with CPh₂(i.e., [Pd₂(L⁴)], [Pd₂(L⁵)]) is less clear, although

this does result in an increased twist angle as a consequence

of the more sterically demanding endo-phenyl substituents,

and, for [Pd₂(L⁴)], increases the Pd···Pd separation.

geometries in which the sum of the equatorial angles for

Ni1 and Ni2 are 359.9 and 359.88, respectively, and the axial

Cl1-Ni1-O3 and O4-Ni2-Cl2 angles are 176.36(13) and

176.73(14)8. The Ni^IIcentres are bound to the imine nitro-

gen donors of the macrocycle only, whilst the other equato-

rial sites are occupied by two methoxy bridges that link the

two metal centres; the axial positions of both cations are oc-

cupied by a chloride anion and a neutral MeOH molecule in

a transoid configuration. It is presumed that the methoxy

groups derive from the deprotonation of MeOH solvent

ꢀ

The syntheses of related diiron complexes of L, [Fe₂(m-

A

O)(L)], have been reported by Sessler and co-workers, who

found that similar Pacman structural motifs were adopted in

the solid state.^[28]As with [Pd₂(L)], the binuclear molecular-

cleft structure is reinforced by the presence of the o-aryl

hinge, although, in this case, the incorporation of the metal-

bridging oxo group does not allow torsional twist (0.38) and

therefore promotes a close M···M separation (3.145 ). Fur-

thermore, we have also observed that monometallic uranyl

under the basic reaction conditions. The Ni N(imine) bond

lengths range from 2.089(5) to 2.136(6) and are similar to

those seen in the crystallographically characterised binuclear

E

Ni^IIcomplex that results from the Ni

(OAc)₂-templated con-

G

densation between pyrrole-2,5-dicarbaldehyde and o-phenyl-

enediamine.^[41]No significant differences were observed be-

ꢀ

complexes of L, for example, [UO

G

tween the bridging Ni OMe bond lengths, which range from

ꢀ

wedged structures in which the pyrrolic hydrogen atoms of

the metal-free N₄-donor compartment form hydrogen bonds

to the endo-uranyl oxygen atom; this results in significant

lengthening of the endo-U=O compared to the exo-U=O

moiety.^[40]The importance of the o-aryl hinge in promoting

the rigid Pacman structural motif is evident by comparison

to similar binuclear accordion Schiff-base diporphyrin and

calixpyrrole complexes that have been structurally charac-

terised by Bowman-James and co-workers,^[19,20]and Brooker

and co-workers, respectively.^[30]In both of these cases, the

presence of conformationally labile alkyl-chain linkers be-

tween the two N₄donor compartments results in flattened

structures in which the metal atoms are highly separated

(M···M 5.39–8.38 ).

2.053(4) to 2.080(4) and are shorter than the terminal Ni

ꢀ

MeOH distances (Ni1 O32.215(4) and Ni2

O4

ꢀ

2.233(4) ). The Ni1 Cl1 and Ni2 Cl2 bond lengths

(2.4660(16) and 2.4371(17) , respectively) are similar to

those in the structurally related [Ni

N

(N,OH=2-(4,4-dimethyl-4,5-dihydrooxazol-2-yl)-propan-2-

ol).^[42]The pyrrole nitrogen atoms remain protonated and

form hydrogen bonds primarily to the methoxy ligands that

bridge the Ni cations (O1···N2 2.856, O1···N33.007, O2···N6

2.919, O2···N7 2.906 ), although close contacts between the

pyrrole nitrogen atoms and axial chloro and MeOH ligands

are also observed (N3···Cl2 3.127, N6···Cl2 3.147, N2···O3

3.152, N7···O3 3.012 ).

3712

www.chemeurj.org

ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Chem. Eur. J. 2007, 13, 3707 – 3723

Binucleating Macrocyclic Clefts

FULL PAPER

Figure 4. Solid-state structures of a) [Ni₂

A

(HOMe)₂

U

(m-OH)₂Cl₂(HOMe)

ACHTREUNG

drawn at 50% probability. For clarity, all hydrogen atoms, except those involved in hydrogen bonding in [Ni₂

A

G

A

ACHTREUNG

OH)₂Cl₂(HOMe) (m-OH)₂Cl₂(HOMe)

A

N

G

ACHTREUNG

The presence of the methoxy bridges results in a relatively

short Ni···Ni separation of 3.122 , albeit longer than that

reported for the above-mentioned binuclear Ni^IIcomplex, in

which constraints of the fully conjugated macrocycle plus

extra acetate ligands result in a Ni···Ni separation of

dent (N2···O1 2.870, N3···O1 2.749, N6···Cl2 3.307, N6···O2

2.767 and N7···O2 2.717 ). The Ni···Ni distance of

2.9660(11) is contracted compared to that of [Ni₂

A

OMe)₂Cl₂(HOMe)₂

A

ACHTREUNG

consequence of the relaxation of steric demand due to the

presence of five-co-ordinate Ni2.

2.512 . However, the Ni···Ni distance in [Ni

(HOMe)

₂(H₄L¹)] can be considered short and comparable

with those in related binuclear Ni^IISchiff-base complexes.^[43]

The solid-state structure of [Ni₂(m-OH)₂Cl₂(HOMe)-

(H₄L⁵)] (Figure 4) is similar to that of [Ni₂

(m-OMe)₂Cl₂-

(HOMe)

₂(H₄L¹)] in that the Ni cations are co-ordinated to

R

A

N

Dimetallic complexes of H₄L in which the ligand remains

protonated have been observed previously by us in the d¹⁰

A

N

adducts [Cd₂

[Ni₂(m-OMe)₂Cl₂

(HOMe)

in [Cd₂(OAc)₄

C

G

U

ACHTREUNG

A

N

G

E

G

ACHTREUNG

5

ꢀ

A

N

E

N

ACHTREUNG

the macrocycle through the imine nitrogen atoms only, and

the pyrrole nitrogen atoms remain protonated. However, in

G

ACHTREUNG

participating in hydrogen-bonding interactions with acetate

ligands, both in the solid state and in solution. Interestingly,

Sessler and co-workers have synthesised the Cu^IIcomplex

[Ni

A

G

N

by two hydroxy bridges, presumably resulting from deproto-

nation of water under the basic reaction conditions, and one

Ni^IIcentre, Ni2, displays a square-pyramidal geometry. As

[(CuCl)

₂(H₄L¹)], in which each metal centre is bound simi-

G

larly to only the imine nitrogen atoms while the remaining

protonated pyrrole groups are involved in intramolecular

hydrogen-bonding interactions.^[27]Thus, macrocycle L can

accommodate metal salts in a variety of ways, and hinged

conformations in the resultant binuclear complexes are pre-

ferred only when complete deprotonation of H₄L is ach-

ieved.

with [Ni

A

G

ACHTREUNG

chloro ligands in [Ni

N

G

ACHTREUNG

transoid conformation, although Cl1 is tilted towards the

vacant site on Ni2 (Ni2-Ni1-Cl1 80.29(5)8). Hydrogen-bond-

ing interactions between the pyrrolic NH groups and the

axial and equatorial ligands on the Ni^IIcations are again evi-

Chem. Eur. J. 2007, 13, 3707 – 3723

ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.chemeurj.org

3713

J. B. Love et al.

contacts (3.30–3.40 ).^[46]The decrease in the Ni···Ni separa-

tion in [Ni₂(L¹)] is also facilitated by its highly twisted con-

formation (F=30.38), and reflects a decrease in steric repul-

sion between the endo-meso-substituents; a similarly large

Table 4. Selected bond lengths [] and angles [8] for the dinickel com-

plexes [Ni₂(m-OMe)₂Cl₂(HOMe)₂(m-OH)₂Cl₂(HOMe)-

(H₄L¹)] and [Ni₂

(H₄L⁵)].

A

G

U

G

ACHTREUNG

A

G

A

ACHTREUNG

A

G

A

ACHTREUNG

torsional angle (22.28) is observed for [Ni

A

ꢀ

Ni1 N1

2.136(6)

2.131(4)

2.053(4)

2.080(5)

2.116(5)

2.089(5)

2.055(4)

2.017(4)

ꢀ

Ni1 N8

Coppercomplexes : The reactions between H₄L and Cu-

ꢀ

Ni1 O1

A

ꢀ

Ni1 O2

complexes [Cu₂(L)] (L=L¹, L², L³) as brown/purple solids in

43–87% yields (see Scheme 3). While this work was in prog-

ress, Sessler and co-workers reported an alternative synthe-

ꢀ

Ni1 O32.215(4)

16(4)

2.3

ꢀ

Ni1 Cl1

2.4660(16)

2.153(5)

2.141(6)

2.061(5)

2.057(4)

2.233(4)

2.4371(17)

–

81.32(16)

77.39(18)

100.96(17)

100.20(17)

176.36(13)

–

81.72(16)

78.41(18)

100.73(17)

98.96(17)

176.76(14)

–

2.4091(17)

2.050(5)

2.063(4)

2.027(4)

2.031(4)

–

2.3256(18)

2.9660(11)

85.93(15)

77.73(18)

98.90(17)

97.35(16)

164.03(12)

80.29(5)

86.31(15)

79.75(18)

93.11(16)

95.29(16)

–

ꢀ

Ni2 N4

ꢀ

Ni2 N5

sis of [Cu₂(L¹)] from the reaction of H₄L¹and Cu

(mesityl)

ꢀ

Ni2 O1

ꢀ

Ni2 O2

followed by aerial oxidation;^[27]we shall concentrate this dis-

cussion on naphthylene-hinged complex [Cu₂(L³)]. The IR

spectrum of [Cu₂(L³)] shows an absorption at 1564 cm^ꢀ1that

ꢀ

Ni2 O4

ꢀ

Ni2 Cl2

Ni···Ni

is characteristic of an imine/pyrrole n(C=N) stretching vibra-

G

O1-Ni1-O2

N1-Ni1-N8

O1-Ni1-N1

O2-Ni1-N8

Cl1-Ni1-O3

Cl1-Ni1-Ni2

O1-Ni2-O2

N4-Ni2-N5

O1-Ni2-N4

O2-Ni2-N5

Cl2-Ni2-O4

Cl2-Ni1-Ni2

tion. The electrospray mass spectrum shows a molecular ion

at m/z 827 and confirms the binuclear nature of [Cu₂(L³)];

elemental analytic data also support this formulation. The

paramagnetism of the Cu^IIcentres precludes the use of

¹H NMR spectroscopy to establish the co-ordination geome-

try of [Cu₂(L³)] in solution. However, the room-temperature

solution magnetic moment was determined by Evansꢁ

method^[47]to be 2.64 m_B, a value which is intermediate be-

tween those expected for either two magnetically indepen-

99.10(5)

U

(S=1, 2.83 m_B), and is indicative of some degree of antifer-

romagnetic coupling (see EPR discussion below). Sessler

and co-workers investigated the magnetic properties of

[Cu₂(L¹)] in solution at 300 K (m_eff=2.00 m_B), and also in the

solid state between 4 and 300 K, and observed a weak anti-

ferromagnetic interaction between the two Cu centres; sim-

ulation of these solid-state data with a modified Bleaney–

Bowers equation resulted in a fit with a J value of (ꢀ41ꢁ

0.2) cm^ꢀ1.^[27]

Synthesis and structural characterisation of [Ni₂(L¹)]: De-

protonation of H₄L¹with KH in THF and subsequent reac-

tion of the resulting potassium salt K₄L¹with [NiCl₂

(dme)]

N

in boiling THF results in formation of the red, binuclear

complex [Ni₂(L¹)] in moderate yield; elemental analytical

data support this formulation. The ¹H NMR spectrum of

[Ni₂(L¹)] shows a single resonance characteristic of the

imine at d=6.64 ppm, and the presence of two separate sin-

glets for endo- and exo-meso-CH₃groups at d=1.57 and

1.35 ppm suggests that a wedged structure is adopted in so-

lution. The single-crystal X-ray structure of [Ni₂(L¹)] was de-

termined for red blocks grown from cooled toluene/pentane

(Figure 4); selected bond lengths and angles are detailed in

Table 2. As expected from the above NMR data, the Ni^II

centre adopts a distorted square-planar geometry within the

Crystallographic characterisation of [Cu₂(L³)] and [Cu₂

(m-

N

py)(L³)]: Purple needles of [Cu₂(L³)] were grown from a sa-

turated solution in CHCl₃and the X-ray crystal structure de-

termined; the crystal structures of [Cu₂(L¹)] and [Cu₂(L²)]

were also determined for comparison, and are described in

the Supporting Information. The solid-state structure of

[Cu₂(L³)] is shown in Figure 5, and selected bond lengths

and angles are displayed in Table 2.

ꢀ

N₄-donor pocket (sum of angles 360.28) with average Ni N-

ꢀ

A

G

1.930 , respectively. The Ni N

(imine) bond lengths are sig-

₂(m-OMe)₂Cl₂(HOMe)₂-

As in [Ni₂(L¹)], the dicopper complexes [Cu₂(L)] adopt

wedged structural motifs in which the macrocyclic frame-

work is distorted, presumably as a consequence of the de-

creased ionic radius of Cu^II. In [Cu₂(L³)], the Cu centres are

square-planar (sum of angles at Cu1 359.888, 0.068 o.o.p.;

sum of angles at Cu2 359.718, 0.065 o.o.p.), with average

nificantly shorter than those in [Ni

(H₄L¹)] and [Ni₂

G

N

tributable to the reduced co-ordination number in [Ni₂(L¹)];

ꢀ

similar Ni N

G

el Schiff-base complexes synthesised by Brooker and co-

workers.^[30]The Ni···Ni separation of 3.632 in [Ni₂(L¹)] is

considerably shorter than that of both the single-pillared

ꢀ

Cu N

ꢀ

G

N

2.029 , respectively. As with [Pd₂(L³)], the presence of

naphthylene hinges appears to induce increased torsional

twist which results in a relatively short Cu···Cu separation

(3.552 ). Significantly, however, Sessler and co-workers

have recently reported two X-ray crystal structure determi-

nations of [Cu₂(L¹)],^[27]in which the Cu···Cu separations are

Pacman analogue [Ni

₂(DPX)]^[45](4.689 , Scheme 1) and

the related dinickel accordion Schiff-base calixpyrrole

(6.682 ),^[30]and reflects the decreased ionic radius of Ni^II.

Furthermore, dinickel diporphyrins which incorporate a

flexible calixarene separator display close interporphyrin

3714

www.chemeurj.org

ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Chem. Eur. J. 2007, 13, 3707 – 3723

Binucleating Macrocyclic Clefts

FULL PAPER

Figure 5. Solid-state structures of a) [Cu₂(L³)], b) [Cu₂

N

solvent molecules have been omitted; displacement ellipsoids are drawn at 50% probability.

3.473 and 4.053 , respectively; these values are different to

the Cu···Cu separation of 4.014 from our structural deter-

mination of [Cu₂(L¹)]. It therefore appears that the interme-

tallic distances in this series of dicopper complexes are un-

predictable, and differences may, in part, be due to crystal

packing effects. Even so, the variation of intermetallic dis-

tance remains small (ca. 0.5–0.6 ), which reinforces further

the perception that this general class of complexes is unable

to undergo vertical expansion to the same degree as the

Pacman diporphyrinic analogues, and so results in a highly

spatially confined binuclear molecular cleft.

plane (0.060 o.o.p), and has little or no interaction with

the pyridine N donor (Cu2···N9 2.983). To accommodate

the pyridine ligand within the cleft, the hinge angle between

the CuN₄planes expands from 53.38 in [Cu₂(L³)] to 59.98 in

[Cu

₂(m-py)(L³)], and the macrocycle undergoes a 12.68 re-

N

duction in torsional twist; this results in an increase of the

Cu1···Cu2 separation to 4.014 . Furthermore, to fit within

the cleft, the pyridine molecule adopts an unusual canted

ꢀ

geometry in which the Cu1 N9 bond does not lie in the

plane of the C₅H₅N ring, and this results in a Cu1-N9-(pyri-

dine centroid) angle of 155.28. This canted geometry also ap-

pears to be reinforced by a hydrogen-bonding interaction

between the C8 meso-methyl proton and the pyridine ring

(C8···centroid 3.686 ; Figure 5c). The bonding of pyridine

A consequence of this constrained geometry is exempli-

fied by formation of the mono-pyridine adduct [Cu₂(m-

R

py)(L³)], which results from crystallisation of [Cu₂(L³)] in

the presence of an excess of pyridine; the elemental analyti-

within the dicopper cleft of [Cu

₂(m-py)(L³)] is best described

G

ꢀ

cal data for [Cu

pyridine molecule. The single-crystal X-ray structure of

[Cu

₂(m-py)(L³)] is shown in Figure 5, with selected bond

lengths and angles detailed in Table 2. Interestingly, the

structure reveals that the two Cu centres in [Cu

₂(m-py)(L³)]

N

as a combination of Cu N co-ordination and a host–guest

interaction, and reflects the high rigidity of the binuclear

cleft environment. In contrast, binuclear copper helicates of

terpyridine or (bis-imino)pyridine ligands display structures

in which the pyridyl N atoms bridge the two metal centres,

ꢀ

ACHTREUNG

AHCTREUNG

are inequivalent with the pyridine bound within the cleft of

the calixpyrrole metallohost. Cu1 adopts a square-pyramidal

geometry in which the metal centre sits 0.343 above the

basal plane and N9 of pyridine occupies the apical position

with Cu N(pyridine) distances that range from 2.180 to

U

2.712 ; furthermore, these bridging pyridyl groups are

twisted with respect to the Cu···Cu vector due to the overall

helicity of these dicopper systems.^[48]

ꢀ

(Cu1 N9 2.258(3) ), while Cu2 remains square-planar

(sum of angles at Cu2 359.688) bound within the N₄-donor

Bimetallic cofacial diporphyrins have been found previ-

ously to act as hosts for guest molecules, in particular for

Chem. Eur. J. 2007, 13, 3707 – 3723

ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.chemeurj.org

3715

J. B. Love et al.

guests incorporating two donor atoms that encourage bimet-

allic binding. For example, the dizinc complex [Zn₂(DPD)],

the latter being determined by the Cu···Cu distance (r) in a

dipolar approximation [Eq. (1)], where b is the electronic

Bohr magneton, and B the applied magnetic field.

AHCTREUNG

where DPD is a diporphyrin ligand with a dibenzofuran

spacer, acts as a 1:1 host for 2-aminopyrimidine, which is

bound to both Zn ions within the diporphyrinic cavity.^[49]

This actually results in the vertical closure of the molecule,

with a Zn···Zn separation of 6.684 compared to 7.775 in

the free host, although both of these M···M separations are

X

^

H ¼

ðbBgS_iþ S_iAI_iÞ þ S₁ꢂ J ꢂ S₂

ð1Þ

i¼1,2

This allows determination of r and of the relative orienta-

tions of the co-ordination planes of the Cu centres to the

Cu···Cu vector. However, because the co-ordination planes

of the two Cu centres are not co-planar in [Cu₂(L¹)], we

must also consider the relative orientations of the two Cu

centres to each other as well as to the Cu···Cu vector. This

contrasts with the approach of Eaton and co-workers for co-

facial dicopper diporphyrins^[53]in which the CuN₄compart-

ments are coplanar and where the local reference frames of

the two Cu ions are coincident; this significantly reduces the

number of parameters required compared to those for

[Cu₂(L¹)].^[54]The procedures used to determine the spin

Hamiltonian and structural parameters are detailed in the

Supporting Information.

considerably longer than that in [Cu

A

such as 1,4-diazabicyclo[2.2.2]octane (DABCO) and even

AHCTREUNG

C₆₀have been bound within Pacman clefts by using strat-

egies that elongate the spacer between the two porphyrin

units. For example, calixarene or diarylurea spacers provide

a

rigid, yet sufficiently elongated separation between

Zn(porphyrin) units to accommodate DABCO,^[50]while the

use of a trans-substituted PdCl₂(pyridylporphyrin)₂complex

as spacer results in a cavity large enough to host C₆₀.^[51]

EPR spectroscopy of [Cu₂(L¹)], [Cu₂(L³)] and [Cu₂

(m-

G

py)(L³)]: The EPR spectra of the binuclear complexes

[Cu₂(L¹)] and [Cu₂(L³)] have been examined for a combina-

tion of X (9.7 GHz), Q (35 GHz) and S (3 GHz) bands in

frozen 2-methyltetrahydrofuran (Me-THF) glass, and the X-

band spectra are shown in Figure 6.

We initially assumed the solution structure of [Cu₂(L¹)] to

be that found in the solid state and this afforded the relative

orientations of the g, A and J matrices. In this assumption

the two-fold symmetry requires the two Cu centres to have

identical parameters, and we further assumed axial local

symmetry at each Cu centre. We refined the simulations, in-

cluding the relative orientations, from this starting point.

Good simulations were obtained with g_xx=g_yy=2.02, g_zz=

2.16, A_xx=A_yy=2010^ꢀ4cm^ꢀ1, A_zz=21010^ꢀ4cm^ꢀ1for both

Cu centres, typical of square-planar {CuN₄} species, with an

interspin distance of r=(4.1ꢁ0.05) and an angle between

the g_zz

ACHTREUNG

analysis gave an angle between the local g_zz

AHCTREUNG

the Cu···Cu vector of 1=(43ꢁ2)8, and an arbitrarily high

isotropic exchange constant of 20 cm^ꢀ1(@gbB_res>A/gb, that

is, there is no singlet–triplet mixing). Note that the large

angle 1ꢃ458 leads to almost equal observed Cu hyperfine

splittings in the “parallel” and “perpendicular” parts of the

EPR spectrum.

The optimised structural parameters obtained from the

frozen-solution EPR spectra do not vary significantly from

the initial values taken from the single-crystal X-ray struc-

ture (q=608, 1=438, r=4.014 ), that is, the initial assump-

tion of very similar solution and solid-state structures ap-

pears to be valid. A further measure of the Cu···Cu separa-

tion can be obtained from the relative intensities of the

DM_S=2 to DM_S=1 transitions,^[53]provided that the metal–

metal separation is long enough for the point-dipole approx-

imation to be valid.^[55]Evaluating the double integral of

these two regions of the X-band spectrum of [Cu₂(L¹)] and

using Eatonꢁs equation^[53]gives r=3.8 , again relatively

close to that observed in the single-crystal X-ray structure.

Although the spectra of [Cu₂(L³)] are qualitatively similar

to those of [Cu₂(L¹)] (Figure 6), there are two important dif-

ferences. Firstly, the spread in magnetic field of the allowed

signals is slightly smaller in [Cu₂(L³)] compared to

Figure 6. X-band EPR spectra of the dicopper complexes [Cu₂(L¹)] (top;

inset: DM_S=ꢁ2 signal) and [Cu₂(L³)] (bottom). Experimental spectra

(black) and simulation for [Cu₂(L¹)] (grey) with the parameters in the

text.

The spectra are typical of an S=1 spin triplet, as evi-

denced by both the zero-field splitting of the DM_S=1 lines

and the appearance of a “forbidden” DM_S=2 “half-field”

transition,^[52]with resolution of nuclear hyperfine coupling

to two ^63,65Cu nuclei, but not to the co-ordinated ¹⁴N nucleus.

Such spectra can, in principle, be analysed to give informa-

tion on the separation and relative orientations of the para-

magnetic ions. Thus, the X-band EPR spectrum of [Cu₂(L¹)]

was simulated by using a full-interaction spin Hamiltonian

incorporating the g and ^63,65Cu nuclear hyperfine (A) matri-

ces of the individual Cu^IIions, and a magnetic exchange

matrix (J) containing isotropic and anisotropic components,

3716

www.chemeurj.org

ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Chem. Eur. J. 2007, 13, 3707 – 3723

Binucleating Macrocyclic Clefts

FULL PAPER

[Cu₂(L¹)]. Secondly, the relative intensity of the half-field

signal is lower for [Cu₂(L³)]. Both these factors imply that

the dipolar coupling is slightly weaker in [Cu₂(L³)] and that,

therefore, in solution the Cu···Cu separation is slightly great-

er. Quantifying this separation from the relative intensity of

the half-field transition at X-band is problematical due to

weak signal intensity and relatively low resolution. Although

the relative intensity of this feature can be enhanced by

measuring at lower frequency (e.g., S-band, see Supporting

Information), this also leads to overlapping of the two re-

gions of the spectrum. A slightly larger Cu···Cu separation

for [Cu₂(L³)] contradicts the single-crystal X-ray diffraction

data, which give Cu···Cu separations of 4.01 and 3.55 for

[Cu₂(L¹)] and [Cu₂(L³)], respectively. This implies that the

structure of [Cu₂(L³)] relaxes significantly in solution, to re-

semble that of [Cu₂(L¹)], in keeping with the fact that the

bite angle (and hence Cu···Cu separation) of [Cu₂(L³)] can

increase to accommodate guest molecules such as pyridine

(see above).

Mn

N

and the Mn^IIamide [Mn

tion of the very air sensitive [Mn₂(L¹)] as a red powder; this

formulation is supported by elemental analysis. X-ray-quali-

ty crystals were grown from hot toluene, and the structure

determined (Figure 7); selected bond lengths and angles are

The insertion of a molecule of pyridine within the cleft, as

in [Cu

the solid-state structure, does not appear to affect the EPR

spectrum of [Cu

₂(m-py)(L³)] in frozen solution. The EPR

spectra of crystalline [Cu

₂(m-py)(L³)] dissolved in Me-THF,

C

Figure 7. Solid-state structure of the dimanganese compound [Mn₂(m-

G

tion of pyridine in [Cu₂

(m-py)(L³)] is a solid-state effect,

E

probably due to favourable crystal packing energies, that is

lost when the sample is dissolved. Unfortunately, solid-state

detailed in Table 5. However, it is immediately clear that,

powder spectra of [Cu₂(L³)] and [Cu₂

A

upon crystallisation, reaction between [Mn₂(L¹)] and traces

broad and no meaningful conclusions could be reached.

It is, therefore, clear that the inability of [M₂(L)] com-

plexes to undergo appreciable vertical cleft expansion miti-

gates against the co-ordination of donor solvents within the

binuclear cleft. This is in contrast to binuclear cofacial dipor-

phyrins, which can accommodate solvents such as pyridine

in more normal co-ordination modes within the cleft; usual-

ly, bulky N-donor ligands such as tert-butylimidazole are em-

ployed as axial base to ensure that no endo co-ordination

occurs. The endo o-ordination of small N-donor ligands by

single-pillared diporphyrin complexes is exemplified by the

X-ray crystal structures of the dicobalt bis-corrole and the

of oxygen or water has occurred to form [Mn

₂(m-OH)(L¹)],

N

Table 5. Selected bond lengths [] and angles [8] for [Mn₂

(m-OH)(L¹)].

T

ꢀ

Mn1 N1

2.034(8)

1.917(7) )

1.913(8)

2.041(7)

1.986(6)

2.211(8)

2.115(8)

2.079(8)

2.304(8)

2.011(6)

N1-Mn1-N2

.N2(23-Mn1-N383

N3-Mn1-N4

N4-Mn1-N1

N5-Mn2-N6

N6-Mn2-N7

N7-Mn2-N8

N8-Mn2-N5

Mn1-O1-Mn2

81.4(3)

ꢀ

Mn1 N2

ꢀ

Mn1 N3

81.8(3)

104.9(3)

76.5(3)

79.1(3)

75.5(3)

103.9(3)

117.5(3)

ꢀ

Mn1 N4

ꢀ

Mn1 O1

ꢀ

Mn2 N5

ꢀ

Mn2 N6

ꢀ

Mn2 N7

ꢀ

Mn2 N8

ꢀ

Mn2 O1

porphyrin-corrole complexes [Co

A

G

N

py)(BCA)] and [Co(exo-py)(endo-py)

A

G

A

ACHTREUNG

ly, where BCA is an anthracyl-bridged bis-corrole ligand

and (H₂PCX) is a xanthyl-bridged porphyrin-corrole ligand

in which the porphyrin cavity is unoccupied.^[16,56]In both of

these cases, one cobalt centre is octahedral with one of the

axial pyridine ligands bound within the binuclear cleft; even

in which a hydroxo ligand bridges the two Mn centres. The

relatively low solution magnetic moment of 6.97 m_B, as deter-

mined by Evansꢁ method (m_calcd=8.37 m_Bfor Mn^IIMn^IInon-

interacting spins), suggests that oxidation of [Mn₂(L¹)] in so-

lution is facile. Furthermore, reactions between dry oxygen

and binuclear Mn^IIhelicates have been observed to form,

so, and unlike [Cu

₂(m-py)(L³)], the wide-ranging vertical ex-

A

pansion available to these ligand systems still results in

nearly linear N(py)-Co-N(py) angles.

after H abstraction from the THF solvent, Mn

Mn₂(m-O)

(m-OH) bridging hydroxo complexes.^[57]

The Mn O1 bond lengths in [Mn₂

valent (1.986(6) and 2.011(6) ) with an Mn1-O1-Mn2 angle

C

G

ACHTREUNG

ꢀ

U

Synthesis and structural characterisation of the manganese

complex [Mn₂(L¹)]: Attempts to synthesise a binuclear man-

ganese complex of H₄L¹by using simple Mn^IIsalts such as

ꢀ

of 117.5(3)8. The Mn O bond lengths in [Mn

A

are comparable to those of other hydroxo-bridged dimanga-

Chem. Eur. J. 2007, 13, 3707 – 3723

ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.chemeurj.org

3717

J. B. Love et al.

nese porphyrins such as the Mn^IIIdimer [{Mn

A

N

Experimental Section

2

+

ꢀ

OH)] , which displays an Mn O distance of 2.026(1) .

General: The compounds Me₂C(C₄H₂N-5,5’-CHO)₂(i),^[25]Ph₂C(C₄H₂N-

5,5’-CHO)₂(ii)^[22]and [Mn (SiMe₃)₂}₂],^[59]were synthesised accord-

(thf)₂{N

However, the Mn-O-Mn angle in [Mn

G

A

ACHTREUNG

acute than that of 152.73(11)8 in the porphyrin system, but

similar to those in complexes incorporating ancillary bridg-

ing ligands, for example, in [{(Tp)Mn}₂(m²:k¹:k¹-pyrazolate)-

ing to literature procedures; all other reagents were used as purchased.

THF and toluene were dried over activated alumina.^[60]The ¹H and

¹³C{¹H} NMR spectra were recorded on a Bruker DPX-300 spectrometer

operating at 300.13 and 75.47 MHz, respectively; residual protio-solvent

served as an internal reference for the former. Magnetic moments were

determined in solution using Evansꢁ method.^[47]Elemental analyses were

carried out by Mr. Stephen Boyer at the London Metropolitan Universi-

ty. Electrospray mass spectra were recorded using a Micromass LCT

spectrometer, IR spectra on a Nicolet 210 FT-IR instrument and UV/Vis

spectra on a Perkin-Elmer Lambda 5 UV/Vis spectrophotometer. EPR

spectra were recorded on Bruker ESP (S- and Q-band) or Bruker EMX

(X-band) spectrometers. Spectral simulations were performed using

Brukerꢁs XSophe software package. The crystal data for the structures

determined in this work are given in Table 6.

ACHTREUNG

AHCTREUNG

ꢀ

eters. For Mn1, the average Mn N

A

ACHTREUNG

sociated with Mn2 are significantly longer (2.097 and

2.258 , respectively). Furthermore, Mn2 is significantly fur-

ther out of the N₄basal plane (0.71 ) than Mn1 (0.38 )

and, as described above, has a longer bond to O1. Thus,

[Mn

₂(m-OH)(L¹)] is best described as a valence-localised

A

Synthesis of tetratosylic acid salts: An equimolar mixture of dialdehyde i

or ii and diamine in warm (ca. 408C) methanol was treated in portions

with solid TsOH·H₂O (4 molar equiv). The resultant bright orange solu-

tion was stirred at 258C for 1 h, after which any precipitate was redis-

solved by warming. The mixture was allowed to stand at room tempera-

ture for 16 h, causing the deposition of the product as orange microcrys-

tals which were collected on a glass frit and air-dried.

H₄L¹

(TsOH)₄: Dialdehyde i (1.00 g, 4.33 mmol), 1,2-diaminobenzene

(0.47 g, 4.33 mmol) and HOTs·H₂O (3.29 g, 0.017 mol) were combined;

yield 72%. ¹H NMR ([D₄]methanol): d_H=8.53(s, 4H, imine), 7.63(m,

4H, H aryl), 7.47 (m, 8H, H aryl+pyrrole), 7.32 (AB d, 8H, arylsulfon-

Mn^IIMn^IIIcomplex, in which the larger Mn^IIcation is associ-

[58]

ꢀ

ated with the longer Mn2 N bond lengths.

Significantly, dimanganese Pacman complexes in which

the porphyrinic compartments are separated by an o-phenyl-

ene spacer have been shown by Naruta and co-workers to

catalyse the oxidation of water to oxygen.^[36,37]Some mecha-

nistic details of this transformation have been elucidated by

using a range of spectroscopic techniques, and it is thought

that intermediate MnOH complexes are formed initially,

which are further oxidised to Mn=O species prior to oxygen

evolution. The implication of binuclear Mn hydroxides in

U

yl), 7.01 (AB d, 8H, arylsulfonyl), 6.63(d, 4H,

J_H,H=4.3Hz, pyrrole),

2.30 (s, 12H, Me arylsulfonyl), 1.94 ppm (s, 12H, Me); ¹³C{¹H} NMR

([D₆]DMSO): d_C=159.6 (s, imine), 149.4 (s, quaternary), 142.7 (s, CH),

142.2 (s, CH), 136.3 (s, quaternary), 131.8 (s, quaternary), 130.7 (s, CH),

130.0 (s, CH), 126.7 (s, CH), 125.9 (s, quaternary), 121.5 (s, quaternary),

115.4 (s, CH), 26.0 (s, quaternary), 21.3ppm (s, CH ₃); IR (KBr): n˜3450,

3216, 2975, 1672, 1653, 1596, 1555, 1284 cm^ꢀ1. ES-MS: m/z (%): 777 [M⁺

ꢀ3TsOH] (100); elemental analysis calcd (%) for C₆₆H₆₈N₈O₁₂S₄: C

61.29, H 5.30, N 8.66; found: C 61.24, H 5.45, N 8.51.

this important process suggests that [Mn

₂(m-OH)(L¹)] may

A

be a suitable structural model for oxygen-evolving dimanga-

nese complexes.

Conclusion

H₄L²

(TsOH)₄: Dialdehyde i (0.40 g, 1.73mmol), 4,5-dimethyl-1,2-diami-

G

nobenzene (0.24 g, 1.73mmol) and HOTs·H ₂O (1.32 g, 6.93 mmol) were

1

We have described the synthesis of a series of metal com-

plexes supported by the Schiff-base calixpyrroles H₄L. The

co-ordination mode of the macrocycle to the metal centres

has been elucidated by X-ray crystallography, as well as by

¹H NMR and EPR spectroscopy where applicable. In partic-

ular, X-ray structural and spectroscopic analysis has shown

that the majority of these binuclear complexes adopt struc-

tural motifs similar to those of single-pillared Pacman dipor-

phyrins, and represent a straightforward and high-yielding

approach to this important binuclear motif. Alternatively,

synthetic procedures in which the pyrrolic nitrogen atoms of

H₄L remain protonated promote the formation of binuclear

adducts in which the metal centres are bound solely to the

imine nitrogen atoms. Unlike their porphyrinic analogues,

complexes of L appear to adopt significantly more rigid

structures, as evidenced by the restricted vertical expansion

and M···M separations in [M₂(L)] complexes, and this fea-

ture may have important consequences in the reactivity of

these systems. We are presently exploring the activity of bi-

metallic complexes of L as catalysts for the transformation

of small molecules.

combined; yield 49%. H NMR ([D₄]methanol): d_H=8.47 (s, 4H, imine),

7.36–7.30 (m, 16H, aryl+arylsulfonyl+pyrrole), 6.99 (AB d, 8H, arylsul-

fonyl), 6.57 (d, 4H, J_H,H=4.3Hz, pyrrole), 2.31 (s, 12H, Me arylsulfonyl),

2.27 (s, 12H, Me), 1.93ppm (s 12H, Me); this complex proved too insolu-

ble for a ¹³C{¹H} NMR spectrum to be recorded; ES-MS: m/z 833 [M⁺

ꢀ3TsOH]; elemental analysis calcd (%) for C₇₀H₇₆N₈O₁₂S₄: C 62.29, H

5.67, N 8.30; found: C 62.19, H 5.57, N 8.14.

H₄L³

(TsOH)₄: Dialdehyde i (0.292 g, 1.27 mmol), 2,3-diaminonaphtha-

lene (0.21 g, 1.33 mmol) and HOTs·H₂O (0.521 g, 2.74 mmol) were com-

bined; yield 73%. ¹H NMR ([D₄]methanol): d_H=8.68 (s, 4H, imine), 7.98

(m, 4H, aryl), 7.87 (m, 4H, aryl), 7.54 (m, 8H, aryl+pyrrole), 7.41 (AB

A

d, 8H, arylsulfonyl), 6.95 (AB d, 8H, arylsulfonyl), 6.64 (d, 4H, J_H,H

=

4.3Hz, pyrrole), 2.17 (s, 12H, Me arylsulfonyl), 1.98 ppm (s, 12H, Me);

this complex proved too insoluble for a ¹³C{¹H} NMR spectrum to be re-

corded; IR (KBr): n˜3450, 3214, 3037, 2978, 1658, 1624, 1598, 1531, 1496,

1458, 1399, 1346, 1283, 1217, 1161, 1122, 1061, 1034, 1010 cm^ꢀ1; ES-MS:

m/z (%): 877 [M⁺ꢀTsO] (100); elemental analysis calcd (%) for

C₇₄H₇₂N₈O₁₂S₄: C 63.77, H 5.21, N 8.04; found: C 63.84, H 5.07, N 8.06.

H₄L⁴

(TsOH)₄: Dialdehyde ii (0.391 g, 1.10 mmol), 1,2-diaminobenzene

G

(0.119 g, 1.10 mmol) and HOTs·H₂O (0.840 g, 4.42 mmol) were com-

bined; yield 44%. ¹H NMR ([D₄]methanol): d_H=8.61 (brs, 4H, imine),

7.54 (AB d, 8H aryl sulfonyl), 7,48 (s, H, aryl phenyl), 7.35 (m, aryl

phenyl), 7.24 (s, H aryl phenyl), 7.12 (AB d, 8H aryl sulfonyl), 2.30 ppm

(s, 12H, CH₃); this complex proved too insoluble for a ¹³C{¹H} NMR

spectrum to be recorded; ES-MS: m/z (%): 853[ M⁺ꢀ3TsOH] (100%);

elemental analysis calcd (%) for C₈₆H₇₆N₈O₁₂S₄: C 66.99, H 4,97, N 7.27;

found: C 66.72, H 4.73, N 6.98.

3718

www.chemeurj.org

ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Chem. Eur. J. 2007, 13, 3707 – 3723

Binucleating Macrocyclic Clefts

Table 6. Crystal data.^[a]

FULL PAPER

H₄L

³(EtOH)₂

H₄L

U

G

ACHTREUNG

A

ACHTREUNG

crystal size [mm]

crystal system

space group

a []

b []

c []

0.640.260.21

monoclinic

P2₁/c

12.9674(8)

23.234(2)

15.1913(10)

90.00

101.976(2)

90.00

4477.3(6)

4, 1.182

0.600.070.06

monoclinic

C2/c

13.747(2)

27.268(3)

14.872(2)

90.00

115.742(2)

90.00

5021.6 (11)

4, 1.127

0.310.160.04

triclinic

P1

0.220.140.11

orthorhombic

Pna2₁

20.222(3)

9.7982(15)

20.330(3)

90.00

4028.2 (10)

4, 1.516

54.4

0.440.120.10

monoclinic

C2/c

29.876(5)

28.398(5)

15.491(3)

90.00

116.619(4)

90.00

11750 (4)

8, 1.348

¯

9.5614(6)

13.1871(9)

15.6343(10)

101.425(1)

92.199(1)

100.410(1)

1894.8 (4)

2, 1.601

a [8]

b [8]

g [8]

V [³]

Z, 1_exptl[Mgm^ꢀ3

2q_max[8]

]

51.0

44.4

55.0

43.0

measured, independent 27266, 10237

reflns

15763, 5725

16324, 8564

24746, 9255

20891, 11276

reflns used in refine-

ment

absorption correction,

T_min, T_max

10237

5725

none

8561

8595

11276

none

0.819, 0.962

0.585, 0.6430.691, 0.884

q_max[8]

27.5

28.9

27.6

parameters

545

280

505

524

719

H-atom treatment

riding model, OH as

rigid rotor

constrained, H₂O refined

with restraints

0.067, 0.157

0.27, ꢀ0.20

632814

constrained to

parent site

0.031, 0.067

0.50, ꢀ0.37

632815

constrained to parent

site

0.055, 0.148

0.84, ꢀ0.54

632816

constrained to parent

site

0.076, 0.186

0.93, ꢀ0.51

632817

R

A

ꢀ3

D1_max, D1_min[e

]

0.20, ꢀ0.17

CSD numbers^[b]

632813

A

[Cu₂(L³)]

U

(m-py)(L³)]

N

crystal size [mm]

crystal system

space group

a []

b []

c []

0.220.120.05

orthorhombic

Fddd

13.7359(15)

30.498(3)

36.387(4)

90.00

15243(5)

16, 1.316

49.8

1.500.420.06

orthorhombic

Pbca

13.2534(13)

24.807(3)

26.755(3)

90.00

8796.4(17)

8, 1.507

55.0

0.220.080.08

triclinic

P1

0.510.100.04

triclinic

P1

15.965(3)

18.173(4)

18.723(4)

69.018(4)

81.972(4)

78.815(3)

4961(3)

¯

9.131(4)

11.942(5)

19.089(8)

93.448(7)

99.244(7)

93.444(7)

2046(2)

a [8]

b [8]

g [8]

V [³]

Z, 1_exptl[Mgm^ꢀ3

2q_max[8]

]

2, 1.473

48.4

4, 1.344

36.8

measured, independent reflns

reflns used in refinement

absorption correction, T_min, T_max

q_max[8]

23789, 4726

4387

multiscan, 0.712, 0.768

27.5

54700, 11102

10108

Multi-scan, 0.464, 1.000

27.5

15135, 7206

7206

multiscan, 0.695, 0.827

25.0

35121, 17239

17238

multiscan, 0.589, 1.000

25.0

parameters

217

614

559

1229

H-atom treatment

constrained to parent site

0.042, 0.089

0.63, ꢀ0.41

632818

constrained to parent site

0.042, 0.128

0.58, ꢀ0.78

632819

constrained to parent site

0.042, 0.082

0.52, ꢀ0.49

632820

constrained to parent site

0.090, 0.275

1.00, ꢀ0.73

632821

R

[F²>2s(F²)], wR(F²)

N

ꢀ3

D1_max, D1_min[e

]

CSD numbers^[b]

[a] All samples were measured using Mo_Karadiation (0.71075 ), scan mode w, at 150 K. All structures were solved by direct methods using SHELXS,

and full-matrix least-squares refinements on F²were carried out using SHELXL. Computer programs: Bruker SMART version 5.624 or 5.625 (Bruker,

2001); Bruker SAINT version 6.02a or 6.36a (Bruker, 2000); Bruker SHELXTL (Bruker, 2001); SHELXS-97 (Sheldrick, 1990); SHELXL-97 (Sheldrick,

1997); enCIFer (Allen et al., 2004); PLATON (Spek, 2003). [b] CCDC-623813–623821 contain the supplementary crystallographic data for this paper.

These data can be obtained free of charge from the Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.

H₄L⁵

aminobenzene (0.061 g, 0.565 mmol) and HOTs·H₂O (0.430 g, 2.26 mmol)

A

excess of NEt₃(ca. 1 mL), causing the immediate loss of orange colour

and deposition of a voluminous yellow precipitate in all cases. The solids

were collected on a glass frit, washed with methanol (310 mL) and

Et₂O (35 mL) and dried at 10^ꢀ2mbar/508C for 2 h.

H₄L¹: Yield 95%. ¹H NMR (CDCl₃+[D₄]methanol): d_H=8.07 (s, 4H,

imine), 7.06 (m, 8H, H aryl), 6.50 (d, 4H, J_H,H=3.7 Hz, pyrrole), 5.97 (d,

4H, J_H,H=3.7 Hz, pyrrole), 3.60 (brs, 4H, pyrrole NH), 1.79 ppm (s, 12H,

Me); ¹³C{¹H} NMR (CDCl₃, [D₄]methanol): d_C=148.4 (s, imine), 146.2 (s,

quaternary), 145.1 (s, quaternary), 129.8 (s, quaternary), 126.0 (s, CH),

117.7 (s, CH), 117.1 (s, CH), 106.7 (s, CH), 36.0 (s, quaternary), 27.3 ppm

ACHTREUNG

were combined; yield 49%. ¹H NMR ([D₆]DMSO): d_H=8.76 (brs, 4H,

imine), 7.53–7.35 (m, 24H, arylsulfonyl+aryl+pyrrole), 7.17–7.00 (m,

20H, arylsulfonyl+aryl+pyrrole), 2.27 ppm (s, 24H, Me arylsulfonyl+

Me); this complex proved too insoluble for a ¹³C{¹H} NMR spectrum to

be recorded; elemental analysis calcd (%) for C₉₀H₈₄N₈O₁₂S₄: C 67.65, H

5.30, N 7.01; found: C 67.03, H 4.99, N 6.87.

Synthesis of the neutral macrocycles H₄L: A solution of the tosylic salt

H₄L(TsOH)₄in warm (ca. 508C) methanol was treated with a large

A

Chem. Eur. J. 2007, 13, 3707 – 3723

ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.chemeurj.org

3719

J. B. Love et al.

(s, Me); IR (KBr): n˜ =3395, 2972, 2874, 1624, 1560, 1469, 1429, 1369,

1264 cm^ꢀ1; UV/Vis (CHCl₃): l_max(e)=345 (75812); ES-MS: m/z (%): 606

[M⁺+1] (100); elemental analysis calcd (%) for C₃₈H₃₆N₈: C 75.47, H

6.00, N 18.53; found: C 75.28, H 5.80, N 18.34.

H₄L²: Yield 97%. ¹H NMR (CDCl₃): d_H=8.12 (s, 4H, imine), 6.85 (s,

4H, aryl), 6.49 (d, 4H, J_HH=2.5 Hz, pyrrole), 6.06 (d, 4H, J_H,H=2.5 Hz,

pyrrole), 2.25 (s, 12H, Me), 1.84 ppm (s, 12H, Me); ¹³C{¹H} NMR

(CDCl₃): d_C=147 (s, imine), 145.1 (s, quaternary), 143.0 (s, quaternary),

134.4 (s, quaternary), 130.7 (s, quaternary), 118.6 (s, CH), 116.4 (s, CH),

106.2 (s, CH), 35.8 (s, quaternary), 27.5 (s, Me), 19.4 ppm (s, Me); ES-

MS: m/z (%): 660 [M⁺+1] (100); elemental analysis calcd for C₄₂H₄₄N₈:

C 76.33, H 6.71, N 16.96; found: C 76.16, H 6.54, N 17.16.

H₄L³: Yield 93%. Crystals suitable for X-ray crystallography were ob-

tained by slow evaporation of a solution of H₄L³in EtOH. ¹H NMR

(CDCl₃/[D₄]methanol): d_H=8.22 (s, 4H, imine), 7.21 (m, 4H, aryl), 7.39

(s, 4H, aryl), 7.23(m, 4H, aryl), 6.58 (d, 4H, J_H,H=3.69 Hz, pyrrole), 6.01

(d, 4H, J_HH=3.69 Hz, pyrrole), 1.83 ppm (s, 4H, CH₃); ¹³C{¹H} (CDCl₃/

[D₄]methanol): d_C=159.1 (s), 152.8 (s), 141.6 (s), 136.5 (s), 131.2 (s),

126.6 (s), 125.6 (s), 121.4 (s), 119.0 (s), 107.8 (s), 43.4 (s), 33.1 (s),

30.2 ppm (s); IR (KBr): n˜3401, 3325, 3049, 2969, 2874, 1607, 1559, 1579,

1489, 1449, 1365, 1270, 1234, 1212, 1171, 154, 1040 cm^ꢀ1; ES-MS: m/z

(%): 705 [M⁺+1] (100); elemental analysis calcd for C₄₆H₄₀N₈: C 78.38,

H 5.72, N 15.90; found: C 78.06, H 6.37, N 15.74.

(m, 2H, pyrrole CH), 2.17 (s, 4H, cyclohexyl CH₂), 1.19 (s, 2H, cyclohex-

yl CH₂), 0.89 ppm (s, 12H, cyclohexyl CH₃); ¹³C{¹H} NMR (CDCl₃): d_H=

178.2 (CHO), 146.4 (CCHO), 131.1 (quaternary pyrrole C), 121.5 (pyr-

role CH), 107.6 (pyrrole CH), 50.6 (cyclohexyl CH₂), 44.5 (cyclohexyl

CH₂), 38.7 (meso C), 31.7 (cyclohexyl CH₃), 30.6 ppm (quaternary cyclo-

hexyl C); ES-MS (+ve mode, MeOH): m/z (%): 327.20 (100) [M+H],

349.19 (41) [M+Na], 653.40 (38) [2M+H], 675.39 (24) [2M+Na]; ele-

mental analysis calcd (%) for C₂₀H₂₆N₂O₂: C 73.6, H 8.0, N 8.6; found: C

73.5, H 7.8, N 8.6.

Synthesis of macrocycle H₄L⁶: A mixture of iii (1.40 g, 4.28 mmol) and o-

phenylenediamine (0.46 g, 4.28 mmol) in methanol was warmed until

most of the solids had dissolved, giving a pale yellow suspension. A solu-

tion of TFA (0.98 g, 8.56 mmol) in MeOH (5 mL) was slowly added,

causing the entire residual solid to dissolve and yielding a bright red solu-

tion. The mixture was stirred for 30 min and the solvents were removed

under vacuum to afford H₄L .

⁶(CF₃COOH)₄as a bright red solid. ES-MS

T

(+ve mode, MeOH): m/z (%): 797.50 (24) [M+H], 843.50 (87)

[M+H+2Na]; elemental analysis calcd (%) for C₆₀H₆₄N₈O₈F₁₂: C 57.5, H

5.1, N 8.9; found: C 57.6, H 5.2, N 8.8. This solid was then redissolved in

MeOH (20 mL) and warmed slightly. An excess of a saturated solution of

KOH in MeOH was added causing a bright yellow solid to precipitate.

The solid was then collected by filtration and washed with cold MeOH

(5 mL), water (until the washings were neutral) and finally pentane

(10 mL), and dried under vacuum to yield 0.98 g, 57.7% of H₄L⁶. Single

crystals suitable for X-ray diffraction were grown by slow evaporation of

a Et₂O solution. ¹H NMR (300 MHz, CDCl₃): d_H=8.07 (s, 4H, imine

CH), 7.04 (m, 8H, phenyl), 6.40 (s, 4H, pyrrole CH), 6.00 (s, 4H, pyrrole

CH), 1.98 (brs, 8H, CH₂), 1.19 (s, 4H, CH₂), 0.88 ppm (s, 24H, CH₃);

H₄L⁴: Yield 95%. ¹H NMR (CDCl₃): d_H=8.09 (s, 4H, imine), 7.00–7.32

(m, 28H, aryl), 6.50 (d, 4H, J_H,H=3.7 Hz, pyrrole), 5.80 ppm (d, 4H,

J

_H,H=3.7 Hz. pyrrole); ¹³C{¹H} NMR (CDCl₃): d_C=151.8 (s, imine), 144.8

(s, quaternary), 144.7 (s, quaternary), 131.3 (s, CH), 129.7 (s, CH), 127.9

(s, CH), 127.3(s, CH), 125.9 (s, CH), 120.6 (s, quaternary), 117.3(s, qua-

ternary), 113.5 (s, CH), 56.6 ppm (s, quaternary); ES-MS: m/z (%): 853

[M⁺+1] (100); elemental analysis calcd for C₅₈H₄₄N₈: C 81.66, H 5.20, N

13.14; found: C 81.53, H 5.31, N 13.22.

H₄L⁵: Yield 97%. ¹H NMR (CDCl₃): d_H=8.08 (s, 4H, imine), 7.31–7.22

(m, 12H, aryl), 7.07–7.04 (m, 8H, aryl), 6.81 (s, 4H, aryl), 6.48 (d, 4H,

13

1

ꢀ

C{ H} NMR (CDCl₃): d_C=151 (ArC N=), 144.5 ( CHN=), 130 (pyr-

rolic quaternary C), 125.8 (aromatic CH), 120 (aromatic CH), 117.2 (pyr-

role CH), 107 (pyrrole CH), 52 (cyclohexyl CH₂), 46 (cyclohexyl CH₂),

40 (meso C), 32.8 (cyclohexyl CH3), 31.7 ppm (quaternary cyclohexyl C).

One quaternary pyrrole C not observed.

Synthesis of palladium(II) complexes: A stirred solution of H₄L in

J

_H,H=3.7 Hz, pyrrole), 5.88 (d, 4H, J_H,H=3.7 Hz, pyrrole), 2.23 ppm (s,

CH₂Cl₂(15 mL) was treated with a solution of Pd(OAc)₂(2 equiv) in

G

12H, Me); ¹³C{¹H} NMR (CDCl₃): d_C=150.8 (s, imine), 144.6 (s, quater-

nary), 142.6 (s, quaternary), 140.4 (s, CH), 134.1 (s, quaternary), 131.3 (s,

CH), 129.5 (s, CH), 127.7 (s, CH), 127 (s, CH), 121.7 (s, quaternary),

116.54 (s, CH), 113.2 (s, CH), 56.4 (s, quaternary), 19.7 ppm (s, Me); ES-

MS: m/z (%): 909 [M⁺+1] (100); elemental analysis calcd for C₆₂H₅₂N₈:

C 81.91, N 5.77, N 12.33; found: C 82.03, H 5.88, N 12.44.

CH₂Cl₂(10 mL). The resultant mixture was stirred for 0.5 h at room tem-

perature, after which the solids had dissolved, and then treated with NEt₃

(ca. 0.2 mL). The resulting deep red solution was stirred for 16 h, reduced

in volume and the crude product precipitated by addition of Et₂O or

Et₂O/pentane. Recrystallisation from CH₂Cl₂/Et₂O resulted in the desired

complexes of acceptable purity.

Synthesis of 1,1-bis(2-pyrrolyl)-3,3,5,5-tetramethylcyclohexane (DPM^Cy):

Pyrrole (40 mL, 346 mmol) was briefly degassed under a stream of N₂

with constant stirring, then 3,3,5,5-tetramethylcyclohexanone (5 mL,

29 mmol) was added. As soon as a catalytic amount of trifluoroacetic

acid was added, a golden colouration of the reaction mixture was ob-

served. Stirring was continued overnight to give a greenish solution.

After neutralisation with 0.1m NaOH (10 mL), the mixture was extracted

into EtOAc (50 mL); the organic phase was then washed with water (3

20 mL) and dried over Na₂SO₄. Subsequent removal of the solvent in

vacuo and trituration of the resulting viscous oil in pentane afforded

crude DPM^Cyas a grey-green powder. Column chromatography (SiO₂,

EtOAc/hexane 1:4, R_f=0.71) afforded 4.24 g, 55% of DPM^Cyas a colour-

A

N

0.445 mmol) were combined; yield 78%. ¹H NMR (CDCl₃): d_H=7.23(s,

4H, imine), 6.77 (m, 4H, aryl), 6.72 (d, 4H, J_H,H=3.9 Hz, pyrrole), 6.62

(m, 4H, aryl), 6.17 (d, 4H, J_H,H=3.9 Hz, pyrrole), 1.60 (s, 6H, CH₃),

1.50 ppm (s, 6H, CH₃); ¹³C{¹H} NMR (CDCl₃): d_C=159.3(s, imine),

152.7 (s, quaternary), 142.8 (s, quaternary), 136.5 (s, quaternary) 126.1 (s,

CH), 124.1 (s, CH), 118.8 (s, CH), 107.7 (s, CH), 43.3 (s, quaternary), 33.1

(s, CH₃), 30.3 ppm (s, CH₃); IR (KBr): n˜ =3442, 3088, 2966, 2924, 1557,

1502, 1473, 1445, 1390, 1327, 1263, 1196 cm^ꢀ1; UV/Vis (CHCl₃): l_max(e):

311 (36293), 414 (22256), 433 nm (22205); ES-MS: m/z (%): 812 [M⁺

+1] (100); elemental analysis calcd (%) for C₃₈H₃₂N₈Pd₂: C 56.10, H 3.96,

N 13.77; found: C 56.34, H 4.12, N 14.01.

1

less oil that crystallised on cooling to ꢀ208C. H NMR (270 MHz, C₆D₆):

A

N

d_H=7.05 (s, 2H, NH), 6.10 (m, 4H, pyrrole CH), 6.00 (m, 2H, pyrrole

CH), 1.70 (s, 4H, cyclohexyl CH₂), 1.0 (s, 2H, cyclohexyl CH₂), 0.82 ppm

(s, 12H, cyclohexyl CH₃); EIMS (+ve mode): m/z (%): 271 [M+H] (48),

205 [Mꢀpyrrole] (60).

0.302 mmol) were combined; yield 68%. ¹H NMR (CDCl₃): d_H=7.29 (s,

4H, imine), 6.78 (d, 4H, J_H,H=3.9 Hz, pyrrole), 6.53 (s, 4H, aryl), 6.23 (d,

4H, J_H,H=3.9 Hz, pyrrole), 2.10 (s, 12H, Me), 1.67 (s, 6H, Me), 1.60 ppm

(s, 6H, Me); ¹³C{¹H} NMR (CDCl₃): d_C=159.7 (s, imine), 152.8 (s, quater-

nary), 141.1 (s, quaternary), 136.9 (s, quaternary), 134.4 (s, quaternary),

125.4 (s, CH), 118.9 (s, CH), 107.9 (s, CH), 43.7 (s, quaternary), 33.1 (s,

Me), 31.2 (s, Me), 19.6 ppm (s, Me); ES-MS: m/z (%): 871 [M⁺+1]

(100); elemental analysis calcd (%) for C₄₂H₄₀N₈Pd₂: C 58.01, H 4.64, N

12.88; found: C 57.89, H 4.57, N 12.81.

Synthesis of 1,1-bis(4-formylpyrrol-2-yl)-3,3,5,5-tetramethylcyclohexane

(iii): POCl₃(2 mL, 21.5 mmol) was added dropwise to a stirred solution

of DPM^Cy(2.65 g, 9.8 mmol) in DMF (25 mL) at 08C causing a deep

cherry red solution to form. The mixture was stirred for 4 h at RT, after

which the solution was once more cooled with an ice bath and the reac-

tion quenched by dropwise addition of H₂O (80 mL). Aqueous KOH

(2m) was then added dropwise until the solution became strongly basic

and colourless solids precipitated. The solids were collected by filtration,

washed with water (215 mL) and dried under vacuum to yield 2.74 g,

85.8% of iii as a colourless powder. ¹H NMR (300 MHz, CDCl₃): d_H=

10.7 (br, NH, 2H), 9.34 (s, CHO, 2H), 6.80 (m„ 2H pyrrole CH), 6.14

A

N

0.437 mmol) were combined; yield 67% Crystals suitable for X-ray crys-

tallography were obtained by Et₂O diffusion into a CH₂Cl₂solution of

1c. ¹H NMR (CDCl₃): d_H=7.39 (s, 4H, imine), 7.15 (m, 4H, aryl), 7.03

(m, 8H, aryl), 6.83(d, 4H,

J_H,H=3.9 Hz, pyrrole), 6.28 (d, 4H, J_H,H=

3720

www.chemeurj.org

ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Chem. Eur. J. 2007, 13, 3707 – 3723

Binucleating Macrocyclic Clefts

FULL PAPER

3.9 Hz, pyrrole), 1.72 (s, 6H, CH₃), 1.60 ppm (s, 6H, CH₃); ¹³C {¹H}

(CDCl₃): d_C=159.1 (s), 152.8 (s), 141.6 (s), 136.5 (s), 131.2 (s), 126.6 (s),

125.6 (s), 121.4 (s), 119.0 (s), 107.8 (s), 43.4 (s), 33.1 (s), 30.2 ppm (s); IR

(KBr): n˜3442, 3051, 2966, 1561, 1473, 1456, 1392, 1330, 1263, 1208, 1079,

1047 cm^ꢀ1; ES-MS: m/z (%) 915 [M⁺+1] (100), 899 [M⁺ꢀCH₃] (50); ele-

mental analysis calcd (%) for C₄₆H₃₆N₈Pd₂: C 60.47, H 3.97, N 12.26;

found: C 60.34, H 3.86, N 12.10.

CH₂Cl₂. After 0.5 h, an excess of NEt₃(ca. 1 mL) was added, and the

deep brown solution stirred for a further 5 h, after which the volume was

reduced under vacuum and the crude material precipitated by the addi-

tion of Et₂O/pentane (1/1). The brown solids were then redissolved in

CHCl₃(10 mL) and washed with water (35 mL), dried over MgSO₄, fil-

tered and evaporated to yield [Cu₂(L)] as brown solids.

A

U

A

(OAc)₂(0.053g,

(0.084 g, 0.354 mmol); yield 76%. UV/Vis (CHCl₃): l_max(e): 379 (34787),

416 nm (27195); ES-MS: m/z (%): 727 [M⁺+1] (100); m_eff=2.49 m_B; ele-

0.235 mmol) were combined; yield 82%. ¹H NMR (CDCl₃): d_H=7.33 (s,

4H, imine), 7.26–6.98 (m, 10H, aryl phenyl), 6.86 (m, 4H aryl), 6.79 (m,

mental analysis calcd for C₃₈H₃₂N₈Cu₂

ACHTREUNG

4H, aryl), 6.69 (d, 4H, J_H,H=3.9 Hz, pyrrole), 5.89 ppm (d, 4H, J_H,H

=

found: C 65.02, H 5.62, N 13.92.

3.9 Hz, pyrrole); ¹³C{¹H} NMR (CDCl₃): d_C=159.9 (s, imine), 151.1 (s,

quaternary), 146.1 (s, quaternary), 142.2 (s, quaternary), 137.2 (s, CH),

129.4 (s, CH), 129.0 (s, CH) 127.8 (s, CH), 127.7 (s, CH), 126.5 (s, quater-

nary) 126.2 (s, quaternary), 126.0 (s, CH), 124.0 (s, CH), 119.0 (s, CH)

112.5 (s, CH), 62.4 ppm (s, quaternary); ES-MS: m/z (%): 1064.4 [M⁺+1]

(100); elemental analysis calcd (%) for C₅₈H₄₀N₈Pd₂: C 65.61, H 3.80, N

10.55; found: C 62.66, H 3.57, N 9.76.

[Cu₂(L²)]: H₄L²(0.200 g, 0.331 mmol) was combined with Cu

ACHTREUNG

(0.143g, 0.602 mmol); yield 87%. ES-MS: m/z (%) 784 [M⁺+1] (100);

m_eff=1.99 m_B; elemental analysis calcd (%) for C₄₂H₄₀N₈Cu₂: C 64.35, H

5.14, N 14.29; found: C 64.01, H 5.00, N 14.23.

A

N

(3mL) was added to a stirred suspension of H ₄L³(0.100 g, 0.142 mmol)

in CH₂Cl₂(ca. 15 mL). The resultant mixture was stirred for 20 min at

room temperature, during which all the solids dissolved, and was then

treated with NEt₃(ca. 0.2 mL). The resultant dark brown solution was

stirred at room temperature for 4 h, reduced in volume and crude

[Cu₂(L³)] precipitated by cooling to ꢀ158C. Recrystallisation from warm

CH₂Cl₂(ca. 5 mL, 408C) yielded 0.050 g, 43% of [Cu₂(L³)] as purple nee-

A

N

0.220 mmol) were combined; yield 78% ¹H NMR (CDCl₃): d_H=7.32 (s,

4H, imine), 7.28–7.23(m, 15H, aryl), 7.08–7.02 (m, 15H, aryl), 6.68 (d,

4H, J_H,H=3.9 Hz, pyrrole), 6.63 (s, 4H, aryl), 5.88 (d, 4H, J_H,H=3.9 Hz,

pyrrole), 2.12 ppm (s, 12H, Me); ¹³C{¹H} NMR (CDCl₃): d_C=159.8 (s,

imine), 150.8 (s, quaternary), 146.3 (s, quaternary), 139.97 (s, CH), 137.2

(s, CH), 134.0 (s, CH), 129.4 (s, CH), 129.0 (s, CH), 127.7 (s, CH), 127.6

(s, CH), 126.3(s, quaternary), 126.1 (s, quaternary), 124.8 (s, CH), 118.5

(s, CH), 112.2 (s, CH), 62.3(s, quaternary), 19.1 ppm (s, CH ₃); ES-MS:

m/z (%): 1118 (100) [M⁺+1]; elemental analysis calcd (%) for

C₆₂H₄₈N₈Pd₂: C 66.61, H 4.33, N 10.02; found: C 66.45, H 4.27, N 10.12.

dles. Crystals of [Cu₂

(m-py)(L³)] suitable for X-ray crystallography were

G

grown by Et₂O diffusion into a CH₂Cl₂/pyridine solution of [Cu₂(L³)].

Data for [Cu₂(L³)]: IR (KBr): n 3418, 3083, 3051, 2967, 2919, 2853, 1564,

1500, 1465, 1386, 1315, 1264, 1205, 1067, 1044 cm^ꢀ1; ES-MS: m/z (%): 827

[M⁺+1] (100); m_eff=2.64 m_B; elemental analysis calcd (%) for

C₄₆H₃₆N₈Cu₂: C 66.73, H 4.38, N 13.53; found: C 66.78, H 4.48, N 13.63.

Synthesis of nickel(II) complexes: A stirred solution of H₄L in CH₂Cl₂

(15 mL) (H₄L¹forms a slurry) was treated with a solution of NiCl₂·6H₂O

(2 equiv) in methanol (ca. 5 mL). The mixture was allowed to stir at

room temperature for 1 h before the addition of Et₃N (ca. 0.5 mL). The

resultant deep red solution was stirred for a further 15 h, after which the

solvents were evaporated under vacuum and the residue washed with

water (25 mL). The solids were isolated by suction filtration, washed with

water (225 mL), dried at 10^ꢀ2mbar/508C for 2 h and recrystallised from

MeOH/CHCl₃/Et₂O.

Data for [Cu

₂(m-py)(L³)]: m_eff=3.09 m_B; elemental analysis calcd (%) for

C₅₁H₄₁N₉Cu₂: C 67.53, H 4.56, N 13.90; found: C 67.48, H 4.49, N 13.89.

Synthesis of [Mn₂(L¹)]: Toluene (15 mL) was added to a stirred mixture

G

of [Mn

N

0.288 mmol). The resulting deep red solution was heated at 908C under

partial vacuum for 12 h and, upon cooling to room temperature, deposit-

ed an amorphous red solid. The solvent was removed under vacuum to

yield 0.061 g, 38% of [Mn₂(L¹)] as a rust red powder. Crystallisation of 5

by slow cooling of a hot saturated toluene solution generated [Mn₂(m-

A

₂(m-OMe)₂Cl₂

G

N

OH)(L¹)] as dark red/brown rods. m_eff=6.97 m_B; elemental analysis calcd

(%) for C₃₈H₃₂N₈Mn₂: C 64.23, H 4.54, N 15.77; found: C 63.94, H 4.56,

N 15.69.

bined with NiCl₂·6H₂O (0.157 g, 0.662 mmol); yield 77%. ES-MS: m/z

(%): 792 [M⁺ꢀ2MeOꢀ2MeOH] (20), 720 [M⁺ꢀ2Clꢀ2MeOꢀ2MeOH]

(100); elemental analysis calcd (%) for C₄₂H₅₀Cl₂N₈Ni₂O₄: C 54.88, H

5.48, N 12.19; found: C 54.98, H 5.37, N 12.37.

A

(m-OH)₂Cl₂

G

N

bined with NiCl₂·6H₂O (0.104 g, 0.441 mmol); yield 89%. ES-MS: m/z

(%): 1024 (100) [M⁺ꢀ2ClꢀMeOHꢀ2OH]; elemental analysis calcd (%)

for C₆₃H₅₈Cl₂N₈Ni₂O₃: C 65.04, H 5.02, N 9.63; found: C 65.04, H 4.85, N

9.47.

Synthesis of [Ni₂(L¹)]: A suspension of KH (0.066 g, 1.65 mmol) in THF

(2 mL) was added to a stirred solution of H₄L¹(0.20 g, 0.33 mmol) in

THF (ca. 15 mL) causing rapid evolution of H₂gas. The resultant mixture

was stirred at room temperature for 1.5 h, then added to a suspension of

Acknowledgements

The authors thank the EPSRC(UK), The Royal Society and the Univer-

sity of Nottingham for their support. M.S. gratefully acknowledges re-

ceipt of a Royal Society Wolfson Merit Award and of a Royal Society

Leverhulme Trust Senior Research Fellowship.

[NiCl₂(dme)] (0.205 g, 0.933 mmol) in THF (20 mL), and the resultant

A

[1] E. Y. Tshuva, S. J. Lippard, Chem. Rev. 2004, 104, 987.

[2] J. P. Collman, R. Boulatov, C. J. Sunderland, L. Fu, Chem. Rev. 2004,

104, 561.

[3] J. P. Collman, L. Fu, P. C. Herrmann, X. Zhang, Science 1997, 275,

949.

[4] D. J. Evans, C. J. Pickett, Chem. Soc. Rev. 2003, 32, 268; D. J. E.

Spencer, A. C. Marr, M. Schrçder, Coord. Chem. Rev. 2001, 219–

221, 1055.

[5] M. D. Fryzuk, S. A. Johnson, Coord. Chem. Rev. 2000, 200–202, 379;

B. A. MacKay, M. D. Fryzuk, Chem. Rev. 2004, 104, 385.

[6] R. H. Holm, P. Kennepohl, E. I. Solomon, Chem. Rev. 1996, 96,

2563.

dark brown suspension was stirred at 808C for 48 h during which the so-

lution turned deep red and a pale precipitate formed. The mixture was

filtered, the filtrate evaporated to dryness under vacuum and the crude

red product recrystallised from toluene at ꢀ158C yielding 0.09 g, 19% of

[Ni₂(L¹)] as red microcrystals. Crystals suitable for X-ray diffraction were

obtained by cooling a saturated solution of [Ni₂(L¹)] in toluene/pentane

(1/1). ¹H NMR (C₆D₆): d_H=6.71 (d, 4H, J_HH=3.93 Hz, pyrrole), 6.64 (s,

4H, imine), 6.49 (m, 8H, aryl), 6.20 (d, 4H, J_H,H=3.90 Hz, pyrrole), 1.57

(s, 6H, CH₃), 1.35 ppm (s, 6H, CH₃); ¹³C{¹H} NMR (C₆D₆): d_C=160.1 (s),

156.7 (s), 142.7 (s), 138.5 (s), 125.9 (s), 124.8 (s), 120.1 (s), 109.5 (s), 40.6

(s), 29.6 (s), 17.7 ppm (s); ES-MS: m/z (%): 705 [M⁺+1] (75), 661 [M⁺

ꢀNi] (100); elemental analysis calcd (%) for C₃₈H₃₂N₈Ni₂: C 63.56, H

4.49, N 15.60; found: C 63.43, H 4.57, N 15.56.

[7] A. L. Gavrilova, B. Bosnich, Chem. Rev. 2004, 104, 349; M. J. McNe-

vin, J. R. Hagadorn, Inorg. Chem. 2004, 43, 8547; J. R. Hagadorn,

M. J. McNevin, G. Wiedenfeld, R. Shoemaker, Organometallics

2003, 22, 4818; G. Rowlands, Tetrahedron 2001, 57, 1865; J. Du Bois,

Synthesis of copper(ii) complexes [Cu₂(L)] (L=L¹, L²): A solution of Cu-

(BF₄)₂·H₂O (2 equiv) in minimal MeOH was combined with H₄L in

Chem. Eur. J. 2007, 13, 3707 – 3723

ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.chemeurj.org

3721

J. B. Love et al.

T. J. Mizoguchi, S. J. Lippard, Coord. Chem. Rev. 2000, 200–202, 443;

E. K. van den Beuken, B. L. Feringa, Tetrahedron 1998, 54, 12985;

B. Bosnich, Inorg. Chem. 1999, 38, 2554.

[23] M. Taniguchi, A. Balakumar, D. Fan, B. E. McDowell, J. S. Lindsey,

J. Porphyrins Phthalocyanines 2005, 9, 554; P. D. Beer, A. G. Chee-

tham, M. G. B. Drew, O. D. Fox, E. J. Hayes, T. D. Rolls, Dalton

Trans. 2003, 603.

[24] S. D. Reid, A. J. Blake, C. Wilson, J. B. Love, Inorg. Chem. 2006, 45,

636.

[8] J. L. Dempsey, A. J. Esswein, D. R. Manke, J. Rosenthal, J. D. Soper,

D. G. Nocera, Inorg. Chem. 2005, 44, 6879.

[9] J. P. Collman, P. S. Wagenknecht, J. E. Hutchinson, Angew. Chem.

1994, 106, 1620; Angew. Chem. Int. Ed. Engl. 1994, 33, 1537.

[10] C. J. Chang, Z.-H. Loh, C. Shi, F. C. Anson, D. G. Nocera, J. Am.

Chem. Soc. 2004, 126, 10013; C. J. Chang, Y. Deng, C. Shi, F. C.

Anson, D. G. Nocera, Chem. Commun. 2000, 1355; R. Guilard, S.

Brands, C. Tardieux, A. Tabard, M. L’Her, C. Miry, P. Gouerec, Y.

Knop, J. P. Collman, J. Am. Chem. Soc. 1995, 117, 11721; L. M. Pro-

niewicz, J. Odo, J. Goral, C. K. Chang, K. Nakamoto, J. Am. Chem.

Soc. 1989, 111, 2105; C. K. Chang, H. Y. Liu, I. Abdalmuhdi, J. Am.

Chem. Soc. 1984, 106, 2725; R. R. Durand, Jr., C. S. Bencosme, J. P.

Collman, F. C. Anson, J. Am. Chem. Soc. 1983, 105, 2710; J. P. Coll-

man, P. Denisevich, Y. Konai, M. Marrocco, C. Koval, F. C. Anson,

J. Am. Chem. Soc. 1980, 102, 6027; J. M. Hodgkiss, C. J. Chang, B. J.

Pistorio, D. G. Nocera, Inorg. Chem. 2003, 42, 8270; B. J. Pistorio,

C. J. Chang, D. G. Nocera, J. Am. Chem. Soc. 2002, 124, 7884; J.

Rosenthal, T. D. Luckett, J. M. Hodgkiss, D. G. Nocera, J. Am.

Chem. Soc. 2006, 128, 6546; J. Rosenthal, B. J. Pistorio, L. L. Chng,

D. G. Nocera, J. Org. Chem. 2005, 70, 1885.

[11] J. P. Collman, H. T. Fish, P. S. Wagenknecht, D. A. Tyvoll, L.-L.

Chng, T. A. Eberspacher, J. I. Brauman, J. W. Bacon, L. H. Pignolet,

Inorg. Chem. 1996, 35, 6746.

[12] J. P. Collman, J. E. Hutchison, P. S. Wagenknecht, N. S. Lewis, M. A.

Lopez, R. Guilard, J. Am. Chem. Soc. 1990, 112, 8206.

[13] J. P. Collman, J. E. Hutchison, M. S. Ennis, M. A. Lopez, R. Guilard,

J. Am. Chem. Soc. 1992, 114, 8074; J. P. Collman, J. E. Hutchison,

M. A. Lopez, R. Guilard, J. Am. Chem. Soc. 1992, 114, 8066; J. P.

Collman, J. E. Hutchison, M. A. Lopez, R. Guilard, R. A. Reed, J.

Am. Chem. Soc. 1991, 113, 2794.

[25] S. D. Reid, A. J. Blake, W. Kçckenberger, C. Wilson, J. B. Love,

Dalton Trans. 2003, 4387.

[26] G. Givaja, A. J. Blake, C. Wilson, M. Schrçder, J. B. Love, Chem.

Commun. 2003, 2508.

[27] J. M. Veauthier, E. Tomat, V. M. Lynch, J. L. Sessler, U. Mirsaidov,

J. T. Markert, Inorg. Chem. 2005, 44, 6736.

[28] J. M. Veauthier, W.-S. Cho, V. M. Lynch, J. L. Sessler, Inorg. Chem.

2004, 43, 1220.

[29] J. L. Sessler, W.-S. Cho, S. P. Dudek, L. Hicks, V. M. Lynch, M. T.

Huggins, J. Porphyrins Phthalocyanines 2003, 7, 97.

[30] R. Li, T. A. Mulder, U. Beckmann, P. D. W. Boyd, S. Brooker, Inorg.

Chim. Acta 2004, 357, 3360.

[31] J. L. Sessler, S. Camiolo, P. A. Gale, Coord. Chem. Rev. 2003, 240,

17.

[32] J. A. Wytko, M. Michels, L. Zander, J. Lex, H. Schmickler, E. Vogel,

J. Org. Chem. 2000, 65, 8709.

[33] C. Janiak, J. Chem. Soc. Dalton Trans. 2000, 3885.

[34] Y. Deng, C. J. Chang, D. G. Nocera, J. Am. Chem. Soc. 2000, 122,

410.

[35] Z.-H. Loh, S. E. Miller, C. J. Chang, S. D. Carpenter, D. G. Nocera,

J. Phys. Chem. A 2002, 106, 11700.

[36] Y. Shimazaki, T. Nagano, H. Takesue, B.-H. Ye, F. Tani, Y. Naruta,

Angew. Chem. 2004, 116, 400; Angew. Chem. Int. Ed. 2004, 43, 98;

K. Ichihara, Y. Naruta, Chem. Lett. 1998, 185; Y. Naruta, M. Sasaya-

ma, K. Ichihara, J. Mol. Catal. A Chem. 1997, 117, 115; Y. Naruta,

M. Sasayama, T. Sasaki, Angew. Chem. 1994, 106, 1839; Angew.

Chem. Int. Ed. Engl. 1994, 33, 1839.

[14] W. Cui, B. B. Wayland, J. Am. Chem. Soc. 2004, 126, 8266; W. Cui,

X. P. Zhang, B. B. Wayland, J. Am. Chem. Soc. 2003, 125, 4994; X.-

X. Zhang, B. B. Wayland, Inorg. Chem. 2000, 39, 5318.

[37] Y. Shimazaki, H. Takesue, T. Chishiro, F. Tani, Y. Naruta, Chem.

Lett. 2001, 539.

[38] G. J. Park, S. Nakajima, A. Osuka, K. Kim, Chem. Lett. 1995, 255.

[39] A. Osuka, S. Nakajima, T. Nagata, K. Maruyama, K. Toriumi,

Angew. Chem. 1991, 103, 579; Angew. Chem. Int. Ed. Engl. 1991, 30,

582.

[40] P. L. Arnold, A. J. Blake, C. Wilson, J. B. Love, Inorg. Chem. 2004,

43, 8206; P. L. Arnold, D. Patel, A. J. Blake, C. Wilson, J. B. Love, J.

Am. Chem. Soc. 2006, 128, 9610.

[41] I. L. Eremenko, S. E. Nefedov, A. A. Sidorov, M. A. Golubnichaya,

P. V. Danilov, V. N. Ikorskii, Y. G. Shvendenkov, V. M. Novotortsev,

I. I. Moiseev, Inorg. Chem. 1999, 38, 3764.

[42] F. Speiser, P. Braunstein, L. Saussine, Inorg. Chem. 2004, 43, 4234.

[43] Z. Xu, L. K. Thompson, D. A. Black, C. Ralph, D. O. Miller, M. A.

Leech, J. A. K. Howard, J. Chem. Soc. Dalton Trans. 2001, 2042.

[44] G. Givaja, A. J. Blake, C. Wilson, M. Schroder, J. B. Love, Chem.

Commun. 2005, 4423.

[45] C. J. Chang, E. A. Baker, B. J. Pistorio, Y. Deng, Z.-H. Loh, S. E.

Miller, S. D. Carpenter, D. G. Nocera, Inorg. Chem. 2002, 41, 3102.

[46] G. Pognon, C. Boudon, K. J. Schenk, M. Bonin, B. Bach, J. Weiss, J.

Am. Chem. Soc. 2006, 128, 3488.

[15] K. M. Kadish, L. Fremond, F. Burdet, J.-M. Barbe, C. P. Gros, R.

Guilard, J. Inorg. Biochem. 2006, 100, 858; K. M. Kadish, J. Shao, Z.

Ou, R. Zhan, F. Burdet, J.-M. Barbe, C. P. Gros, R. Guilard, Inorg.

Chem. 2005, 44, 9023; K. M. Kadish, J. Shao, Z. Ou, L. Fremond, R.

Zhan, F. Burdet, J.-M. Barbe, C. P. Gros, R. Guilard, Inorg. Chem.

2005, 44, 6744; K. M. Kadish, L. Fremond, Z. Ou, J. Shao, C. Shi,

F. C. Anson, F. Burdet, C. P. Gros, J.-M. Barbe, R. Guilard, J. Am.

Chem. Soc. 2005, 127, 5625; R. Guilard, F. Burdet, J.-M. Barbe, C. P.

Gros, E. Espinosa, J. Shao, Z. Ou, R. Zhan, K. M. Kadish, Inorg.

Chem. 2005, 44, 3972; K. M. Kadish, Z. Ou, J. Shao, C. P. Gros, J.-M.

Barbe, F. Jerome, F. Bolze, F. Burdet, R. Guilard, Inorg. Chem.

2002, 41, 3990; R. Guilard, F. JØrome, C. P. Gros, J.-M. Barbe, Z.

Ou, J. Shao, K. M. Kadish, C. R. Acad. Sci. Paris 2001, 4, 245; R.

Guilard, F. Jerome, C. P. Gros, J.-M. Barbe, Z. Ou, J. Shao, K. M.

Kadish, C. R. Acad. Sci. Ser. IIc Chim. 2001, 4, 245; R. Guilard, C. P.

Gros, F. Bolze, F. Jerome, Z. Ou, J. Shao, J. Fischer, R. Weiss, K. M.

Kadish, Inorg. Chem. 2001, 40, 4845.

[16] R. Guilard, F. Jerome, J.-M. Barbe, C. P. Gros, Z. Ou, J. Shao, J.

Fischer, R. Weiss, K. M. Kadish, Inorg. Chem. 2001, 40, 4856.

[17] J. L. Sessler, D. Seidel, Angew. Chem. 2003, 115, 5292; Angew.

Chem. Int. Ed. 2003, 42, 5134; A. Jasat, D. Dolphin, Chem. Rev.

1997, 97, 2267.

[18] W. B. Callaway, J. M. Veauthier, J. L. Sessler, J. Porphyrins Phthalo-

cyanines 2004, 8, 1.

[19] N. N. Gerasimchuk, A. Gerges, T. Clifford, A. Danby, K. Bowman-

James, Inorg. Chem. 1999, 38, 5633.

[47] E. M. Schubert, J. Chem. Educ. 1992, 69, 62; D. F. Evans, J. Chem.

Soc. 1959, 2003.

[48] E. C. Constable, A. J. Edwards, M. J. Hannon, P. R. Raithby, J.

Chem. Soc. Chem. Commun. 1994, 1991; E. C. Constable, T. Kulke,

M. Neuburger, M. Zehnder, Chem. Commun. 1997, 489; M. G. B.

Drew, A. Lavery, V. McKee, S. M. Nelson, J. Chem. Soc. Dalton

Trans. 1985, 1771; C. Piguet, G. Bernardinelli, A. F. Williams, Inorg.

Chem. 1989, 28, 2920; K. T. Potts, M. Keshavarz, F. S. Tham, H. D.

Abruna, C. Arana, Inorg. Chem. 1993, 32, 4450; T. Yano, R. Tanaka,

I. Kinoshita, K. Isobe, L. J. Wright, T. J. Collins, Chem. Commun.

2002, 1396.

[20] W. A. Reiter, A. Gerges, S. Lee, T. Deffo, T. Clifford, A. Danby, K.

Bowman-James, Coord. Chem. Rev. 1998, 174, 343.

[21] F. V. Acholla, F. Takusagawa, K. Bowman-Mertes, J. Am. Chem.

Soc. 1985, 107, 6902.

[22] J. B. Love, A. J. Blake, C. Wilson, S. D. Reid, A. Novak, P. B. Hitch-

cock, Chem. Commun. 2003, 1682.

[49] C. J. Chang, Z.-H. Loh, Y. Deng, D. G. Nocera, Inorg. Chem. 2003,

42, 8262.

3722

www.chemeurj.org

ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Chem. Eur. J. 2007, 13, 3707 – 3723

Binucleating Macrocyclic Clefts

FULL PAPER

[50] D. Jokic, C. Boudon, G. Pognon, M. Bonin, K. J. Schenk, M. Gross,

J. Weiss, Chem. Eur. J. 2005, 11, 4199; S. Yagi, M. Ezoe, I. Yonekura,

T. Takagishi, H. Nakazumi, J. Am. Chem. Soc. 2003, 125, 4068.

[51] D. Sun, F. S. Tham, C. A. Reed, L. Chaker, M. Burgess, P. D. W.

Boyd, J. Am. Chem. Soc. 2000, 122, 10704.

[52] R. L. Belford, N. D. Chasteen, R. E. Tapscott, J. Am. Chem. Soc.

1969, 91, 4675; J. F. Boas, R. H. Dunhill, J. R. Pilbrow, R. C. Srivas-

tava, T. D. Smith, J. Chem. Soc. A 1969, 94; J. F. Boas, J. R. Pilbrow,

C. R. Hartzell, T. D. Smith, J. Chem. Soc. A 1969, 572; R. H. Dun-

hill, J. R. Pilbrow, T. D. Smith, J. Chem. Phys. 1966, 45, 1474; R. H.

Dunhill, J. R. Pilbrow, T. D. Smith, J. Chem. Soc. A 1968, 2189.

[53] S. S. Eaton, K. M. More, B. M. Sawant, G. R. Eaton, J. Am. Chem.

Soc. 1983, 105, 6560.

[57] F. Franchesci, G. Guillemot, E. Solari, C. Floriani, N. Re, H. Birke-

dal, P. Pattison, Chem. Eur. J. 2001, 7, 1468; E. Gallo, E. Solari, N.

Re, C. Floriani, A. Chiesi-Villa, C. Rizzoli, Angew. Chem. 1996, 108,

2113; Angew. Chem. Int. Ed. Engl. 1996, 35, 1981.

[58] H.-R. Chang, S. K. Larsen, P. D. W. Boyd, C. G. Pierpont, D. N. Hen-

drickson, J. Am. Chem. Soc. 1988, 110, 4565; S. Gou, Q. Zeng, Z.

Yu, M. Qian, J. Zhu, C. Duan, X. You, Inorg. Chim. Acta 2000, 303,

ˇ

175; N. Shaikh, A. Panja, S. Goswami, P. Banerjee, P. Vojtísek, Y.-Z.

Zhang, G. Su, S. Gao, Inorg. Chem. 2004, 43, 849.

[59] B. Horvath, R. Moeseler, E. G. Horvath, Z. Anorg. Allg. Chem.

1979, 450, 165.

[60] A. B. Pangborn, M. A. Giardello, R. H. Grubbs, R. K. Rosen, F. J.

Timmers, Organometallics 1996, 15, 1518.

[54] S. S. Eaton, G. R. Eaton, C. K. Chang, J. Am. Chem. Soc. 1985, 107,

3177.

[61] J. L. Sessler, E. Tomat, T. D. Mody, V. M. Lynch, J. M. Veauthier, U.

Mirsaidov, J. T. Markert, Inorg. Chem. 2005, 44, 2125.

[55] L. Nordenskiold, A. Laaksonen, J. Kowalewski, J. Am. Chem. Soc.

1982, 104, 379.

[56] J.-M. Barbe, F. Burdet, E. Espinosa, R. Guilard, Eur. J. Inorg.

Chem. 2005, 1032.

Received: July 11, 2006

Revised: October 5, 2006

Published online: January 24, 2007

Chem. Eur. J. 2007, 13, 3707 – 3723

ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.chemeurj.org

3723

Article Doi

Design and synthesis of binucleating macrocyclic clefts derived from schiff-base calixpyrroles

DOI: 10.1002/chem.200600989

Source and publish data:

Authors:

Article abstract of DOI:10.1002/chem.200600989

Full text of DOI:10.1002/chem.200600989

Products guided by the article

R&D Labs maybe for 943518-15-8

Relevant to this article

Hot Product