Multivalent 1-Oxa-3,5,7-triazahepta-1,3,5-trienes: Synthesis, structural properties and metal coordination

FULL PAPER

DOI: 10.1002/ejoc.200800778

Multivalent 1-Oxa-3,5,7-triazahepta-1,3,5-trienes: Synthesis, Structural

Properties and Metal Coordination^[‡]

Jan-Bernd Greving,^[a]Henrik Behrens,^[a]Roland Fröhlich,^[a]and Ernst-Ulrich Würthwein*^[a]

Keywords: Ligand design / Oligonitriles / N ligands / Pincer complexes / Ring-opening reaction

Nucleophilic ring opening of bis- and tris(1-oxa-3,5-diazin-

ium) salts 1 with n-propylamine leads to the bis- and tris-

(armed) oligonitrile derivatives 3 and 8 with secondary amino

groups in the side chain. Alternatively, treatment of simple

1-oxa-3,5-diazinium salts 2 with primary and secondary di-

and triamines offers a convenient pathway for the synthesis

of bis- and tris(armed) oligonitriles 4, 5 and 7. 2,6-Diami-

nopyridine furnishes the new pincer-type ligand 6 upon reac-

tion with 1-oxa-3,5-diazinium salt 2a. Multivalent oligoni-

triles 4, 6, 7 and 8 containing secondary amino groups are

able to form intra- and intermolecular hydrogen bonds in the

solid state as detected by X-ray crystallography. The oligoni-

triles 3a,b, 4b,d,h, 6 and 7a form coordination complexes with

various Zn^II, Cu^II, Co^II, Ni^IIand Pd^IIsalts acting as bidentate

ligands to give six-membered chelates of 1:1, 1:2 and 2:2 li-

gand/metal ion ratios. More complex structures are obtained

from pincer ligand 6 with PdCl₂[compound 6·(PdCl₂)₂] and

from the tridentate ligand 7a in reactions with Ni(ClO₄)₂

(compound 9). All new complexes were characterized by X-

ray crystallography.

Germany, 2008)

The shorter homologues of oligonitriles, e.g. 1,3,5-triaza-

pentadienes^[4]and N-acylamidines^[5]as nitrogen analogues

of the intensively investigated β-diketimines and β-imino

ketones, respectively, have also found applications in coor-

dination chemistry, as they are quite potent bidentate che-

lating ligands.^[6,7]In general, treatment of these ligands with

transition metal ions leads to six-membered chelate com-

plexes. These compounds also show activity as pre-catalysts

in Heck, Suzuki–Miyaura and Sonogashira cross-coupling

reactions.^[4,5]

In this paper we extend our studies on oligonitriles to

such novel polyfunctional bis- and tris(armed) derivatives,

which may find use in supramolecular chemistry. For their

synthesis we are describing two different, yet alternative

routes for examples with two or three binding sites of the

1-oxa-3,5,7-triazahepta-1,3,5-triene type. Using both com-

plementary routes, we obtained the title compounds con-

taining two or three nonplanar, three-dimensional C=N–

C=N–C=O chains, which are interconnected by various

flexible or stiff, aliphatic or aromatic linkers. As in the other

known examples, each chain with its lone pairs at the nitro-

gen and oxygen atoms is expected to serve as potent multi-

dentate ligand, thus building up a multivalent complexation

environment. Furthermore, the numerous C=N bonds may

give rise to π-complexation. Depending on one hand on the

nature of the spacer between the chains and on the other

hand on the transition metal ion, it was possible to synthe-

sise both mononuclear and dinuclear metal complexes with

individual or cooperative properties. The structures in the

solid state of some of the new ligands and all of the new

complexes were studied by X-ray diffraction.

Introduction

In recent years, oligonitriles as heteroanalogues of poly-

acetylenes have found our synthetic and theoretical interest

for various reasons. Due to the polyunsaturated chain of

adjacent C=N units, special electronic and molecular struc-

tures as well as interesting redox and NLO properties are

observed.^[1]These oligomers offer oxygen and nitrogen lone

pairs as potential binding sites for metal complexation.^[1,2]

In particular, branched pyridine-based pincer ligands

(Scheme 1) have found applications as powerful ligands for

the complexation of various transition metal ions.^[3]Such

novel pincer-type ligands are thermally, moisture- as well

as air-stable, and their palladium complexes display high

catalytic activity, e.g. in Suzuki–Miyaura cross-coupling re-

actions.

Scheme 1.

[‡] Unsaturated Hetero Chains, XVI. Part XV: Ref.^[12]

[a] Organisch-Chemisches Institut, Westfälische Wilhelms-Uni-

versität,

Corrensstraße 40, 48149 Münster, Germany

Fax: +49-251-83-39772

E-mail: wurthwe@uni-muenster.de

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Eur. J. Org. Chem. 2008, 5740–5754

Multivalent 1-Oxa-3,5,7-triazahepta-1,3,5-trienes

dichlorides like terephthalic dichloride, adipic dichloride or

sebacic dichloride, disubstituted cyanamides and a Lewis

acid (tin tetrachloride in dichloromethane as solvent or neat

tin tetrachloride). The subsequent nucleophilic ring opening

by treatment with n-propylamine leads to the bis(armed)

compounds 3a–c (Scheme 3) in 37 to 79% yield.

On the other hand, the use of monoacyl chlorides, cyan-

amides and Lewis acids in the first reaction step leads to

simple 1-oxa-3,5-diazinium salts 2.^[8,9]Treatment of such

heterocycles (2a) with suitable diamines (aliphatic diamines,

trans-1,2- and trans-1,4-cyclohexanediamines and m- and p-

xylylenediamines) provides access to two-armed ligands 4a–

h (Scheme 4) in 34–65% yield.

Results and Discussion

Synthesis of the Di- and Trifunctional 1-Oxa-3,5,7-triaza-

heptatrienes

For a detailed study of the properties of di- and trifunc-

tional oligonitriles with multiple 1-oxa-3,5,7-triazaheptatri-

ene subunits we developed two alternative synthetic ap-

proaches based on the nucleophilic ring opening reaction

of 1-oxa-3,5-diazinium salts, as first reported by Fuks, Stre-

belle and Wenders,^[8]and then further investigated in our

group.^[9]Both these synthetic pathways are based on the

modular use of amines and 1-oxa-3,5-diazinium salts. On

one hand monoamines as nucleophiles were treated with

bis- and tris(1-oxa-3,5-diazinium) salts 1 as the respective

bis- and tris(electrophiles), leading to the corresponding

polyfunctional 1-oxa-3,5-diazahexatriene derivatives 3 with

peripheral amino groups at carbon atom C6, originating

from the applied amine. On the other hand, we applied di-

and triamines as bis- or tris(nucleophiles) in ring opening

reactions of simple 1-oxa-3,5-diazinium salts 2 for the syn-

thesis of the respective 1-oxa-3,5,7-triazahepta-1,3,5-trienes

4 (Scheme 2), where the amino functions (N7) are part of

the molecular backbone.

The bis(electrophilic) pathway starts with the synthesis

of bis(1-oxa-3,5-diazinium) salts 1a–c^[10]from dicarbonyl Scheme 4.

Scheme 2.

Scheme 3.

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J.-B. Greving, H. Behrens, R. Fröhlich, E.-U. Würthwein

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Scheme 5.

In order to extend the scope of this bis(nucleophilic) bamoyl functions (Scheme 6). This type of compounds may

route, 1-oxa-3,5-diazinium salts 2a and 2b were also treated well serve as a polyvalent ligand for metal coordination (see

with secondary amines like piperazine, N,NЈ-dimethylethyl- below).

enediamine or N,NЈ-diethyl- and N,NЈ-diphenyl-p-xylylene-

diamine. In all cases, we obtained the respective divalent

oligonitriles 5a–e in yields of 9–79% (Scheme 5, Table 1).

Sterically demanding nucleophiles gave the lowest yields.

Table 1. Substitution patterns for compounds 2 and 5 and (isolated)

yields for compounds 5.

Scheme 6.

2

5

R¹

R²

–Z–

R³

Yield

For the synthesis of oligonitrile derivatives with three

a

b

a

b

a

b

c

d

e

f

NEt₂

Ph

–(CH₂CH₂)–

–(1,4-CH₂C₆H₄CH₂)–

–(CH₂CH₂)– 77%

arms we also used the two approaches mentioned above.

By treatment of 1,3,5-oxadiazinium salts 2 with a suitable

triamine we were able to prepare a series of crystalline tris-

(armed) 1-oxa-3,5-diazahexatrienes 7a–d with a different

number and locations of amino groups and, consequently,

differing electronic properties, in yields of 18–63%

Me

Et

Ph

79%

50%

10%

9%

4-BrC₆H₄4-BrC₆H₄–(1,4-CH₂C₆H₄CH₂)–

NEt₂Ph –(1,4-CH₂C₆H₄CH₂)–

4-BrC₆H₄4-BrC₆H₄–(1,4-CH₂C₆H₄CH₂)–

12%

Interestingly, this approach is also applicable to the syn- (Scheme 7).

thesis of pincer ligands. Treatment of 2a with 2,6-diami-

In an analogous manner, tris(electrophiles) like 1d^[11]re-

nopyridine affords compound 6, which for the first time act with primary amines to give the corresponding tris-

offers seven adjacent C–N subunits with two terminal car- (armed) 1-oxa-3,5-diazahexatriene derivative 8 (Scheme 8)

Scheme 7.

Scheme 8.

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Multivalent 1-Oxa-3,5,7-triazahepta-1,3,5-trienes

in 37% yield. The crystal diffraction study of 1d, carried sulting in a supramolecular grid (Figure 1). For 4g, in the

out in our laboratory, indicates a perfect planar molecular –N–H···O=C subunit the N–O distance amounts to

structure of the trication of 1d.

3.058 Å.

In contrast, due to the close neighbourhood of the oli-

gonitrile chains, 4h prefers intramolecular N–H···O interac-

tions (N–O distance 2.824, 2.995 Å) between the nonplanar,

strongly twisted three-dimensional chains resulting in a

doubly bridged pseudo-polyazamacrocyle (Figure 2) with-

out intermolecular aggregation.

Structural Properties of the Di- and Trifunctional 1-Oxa-

3,5,7-triazaheptatrienes

Recently,^[12]we reported on the formation of hydrogen-

bonded superstructures, which were observed in the case of

monofunctional oligonitriles containing primary or second-

ary amino groups. In those structures intermolecular hydro-

gen bonds were formed by the amine hydrogen atom of one

molecule and the carbonyl oxygen atom of the neighbour-

ing molecules as hydrogen-bond acceptors. Analogously,

oligonitriles containing secondary amino groups like 4, 6, 7

and 8 are expected to form intra- and intermolecular hydro-

gen bonds. Indeed, such hydrogen bonds are observed in

the solid state by X-ray diffraction for 4d,g,h and 7b causing

interesting aggregation phenomena in the solid state.

Due to the difunctional nature of the 1,4-diaminocyclo-

hexane-based oligonitrile 4g four intermolecular N–H···O

hydrogen bonds to four different molecules are found re-

Figure 2. Molecular structure of 4h in the solid state.

Intramolecular interactions are also observed in solid-

state structures for the examples of the two trimethylene-

based oligonitriles 4b and the corresponding tris(armed)

compound 7b. In 7b, due to the flexibility of the spacers,

the amine protons are in plane with the carbonyl oxygen

atoms and contribute to three intramolecular hydrogen

bonds resulting in three pseudo-polyazamacrocycles, which

are interconnected by the central tris(2-aminoethylamine)

unit (Figure 3). For 7b, the N–O distances are found to be

between 2.827 and 2.860 Å and for 4b at 2.775 Å.

Figure 3. Molecular structure of 7b in the solid state.

Complexation Reactions

Various metal complexes of difunctional oligonitriles

were easily obtained by co-dissolving the metal salts with

the ligands 3–7 and subsequent crystallization, which was

usually induced by adding less polar solvents to the reaction

mixture.

Figure 1. Molecular structure of 4g in the solid state (top) and

aggregation by hydrogen bonding (bottom).

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J.-B. Greving, H. Behrens, R. Fröhlich, E.-U. Würthwein

FULL PAPER

Thus, 3a and 3b form a common type of a dinuclear che-

late complex with Zn^II, Co^IIund Cu^IIhalogenides, indepen-

dent of the nature of the metal salt and the linker separating

the two functional oligonitrile chains (Scheme 9).

Figure 5. Molecular structures of 3b·CuCl₂in the solid state.

Scheme 9.

According to Scheme 9 and Figures 4 and 5 the metal

centres coordinate in all cases to the oxygen atom of the

carbamoyl mojety and to the nitrogen atom N5 forming a

six-membered non-planar chelate structure with a tetrava-

lent metal centre. Interestingly, the metal–metal distances

of 3a·ZnBr₂(Figure 4) and 3a·CoCl₂(Zn–Zn 11.561 Å; Co–

Co 11.487 Å) are longer than in the complexes 3b·ZnBr₂

and 3b·CuCl₂(Zn–Zn 8.959 Å; Cu–Cu 7.686 Å). This ob-

servation might be explained by the stiffness of the phenyl-

derived spacer in 3a. Consequently, the metal ions of

3b·ZnBr₂and 3b·CuCl₂are bonded more on the inside of

the ligand, while 3a acts more as an exo-receptor. As ex-

pected, the Zn^IIand Co^IIions show a tetrahedral environ-

ment, whereas in 3b·CuCl₂a strongly distorted Cu^IIligand

sphere is observed (Figure 5).

Scheme 10.

Figure 4. Molecular structures of 3a·ZnBr₂in the solid state.

Due to the mobility of the amine protons the multi-

armed oligonitriles 4 with secondary amines as part of the

CN backbone offer an even larger structural variety. De-

pending on the nature of the spacer between the chains it

is possible to synthesize 1:1 as well as 2:2 metal complexes

(Scheme 10).

In the dinuclear 2:2 oligonitrile/metal complex

4b·Ni(ClO₄)₂two of the bis(armed) oligonitriles 4b act as

bis(bidentate) chelate ligands with the individual oligoni-

trile chains linked together by two octahedrally coordinated

Figure 6. Molecular structure of 4b·Ni(ClO₄)₂in the solid state.

If the alkyl spacer between the individual oligonitrile

nickel(II) ions (Figure 6). Here, the metal–metal distance chains of the ligand is elongated to eight methylene groups

amounts to 7.75 Å. (4d), cooperative effects between both oligonitrile chains are

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Multivalent 1-Oxa-3,5,7-triazahepta-1,3,5-trienes

observed. In this case the bis(armed) oligonitrile ligand acts

as a tetradentate “pincer” ligand and forms a cyclic struc-

ture [4d·Ni(NO₃)₂] coordinating the metal centre. This com-

plex is further stabilized by intramolecular N–H···O interac-

tions, caused by the amine protons and the coordinated ni-

trate ions (Figure 7).

Scheme 11.

The Pd^IIcentres of 6·(PdCl₂)₂are coordinated by four

different nitrogen donor atoms of the symmetrical, bifunc-

tional ligand 6 (Figure 9). Each binding site forms a six-

membered chelate ring. Similar as in the other dinuclear

complexes, the Pd–Pd distance of 3.338 Å excludes any

stronger metal–metal interaction.

Figure 7. Molecular structure of 4d·Ni(NO₃)₂in the solid state.

Furthermore, we were also able to isolate a chiral

nickel(II) complex, 4h·Ni(NO₃)₂, (Figure 8) from the chiral

trans-1,2-cyclohexanediamine-derived ligand 4h and

nickel(II) nitrate in acetonitrile after precipitation with di-

ethyl ether in 88% yield. The structure displays the mutual

coordination abilities of both triazapentadienes and N-acyl-

amidines. Hence, one chain coordinates using the oxygen

atom of the carbamoyl mojety and the nitrogen atom N5

(as in 3a·ZnBr₂and 3a·CoCl₂, Figure 4). The second bind-

ing site coordinates to the nickel ion involving two nitrogen

atoms, thus forming a typical six-membered chelate ring as

in 1,3,5-triazapentadiene complexes described in the litera-

ture.^[4]This coordination mode produces an additional

seven-membered chelate ring incorporating the cyclohexyl

moiety.

Figure 9. Molecular structure of 6·(PdCl₂)₂in the solid state.

The solid-state structure of the octahedral complex

6·Ni(NO₃)₂shows many similarities with other pyridine-

based pincer complexes reported recently from our labora-

tory:^[3]here, the ligand 6 acts in a pentadentate fashion,

while one solvent molecule (methanol) occupies the sixth

coordination site (Figure 10).

Figure 8. Molecular structure of 4h·Ni(NO₃)₂in the solid state.

Some of the polyvalent, structurally flexible ligands are

able to interact with different metal ions, each in an individ-

ual manner. Thus, treatment of the pincer ligand 6 with

bis(benzonitrile)palladium(II) dichloride yielded to the di-

nuclear coordination compound 6·(PdCl₂)₂, whereas nicke-

l(II) chloride produced the mononuclear complex

6·Ni(NO₃)₂(Scheme 11).

Figure 10. Molecular structure of the dication of 6·Ni(NO₃)₂in the

solid state.

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J.-B. Greving, H. Behrens, R. Fröhlich, E.-U. Würthwein

FULL PAPER

Similar to 4h, the tris(armed) ligand 7a forms a 1:1 tris- has been employed for a new pincer-type ligand 6 in the

(chelate) complex, 7a·Ni(ClO₄)₂, featuring a 1,3,5-triaza- reaction with 1-oxa-3,5-diaziniuim salt 2a. Aggregation

pentadiene-derived chelate ring as well as a typical N-acyl- properties of the multivalent oligonitriles 4, 6, 7 and 8 con-

amidine coordination (Scheme 12, Figure 11). Interestingly, taining secondary amino groups have been recognized by

one of the three arms of the ligand is shortened during the X-ray crystallography. These compounds are able to form

complexation reaction: If 7a is treated with nickel(II) per- intra- and intermolecular hydrogen bonds in the solid state.

chlorate and triethylamine in methanol as solvent at 55 °C, The oligonitriles 3a,b, 4d,h, 6 and 7a form coordination

one of the three diethylcarbamoyl groups is cleaved off by complexes with various Zn^II, Cu^II, Co^II, Ni^IIand Pd^IIsalts

nucleophilic attack producing an N-benzoylbenzamidine acting as bidentate ligands to give six-membered chelates.

subunit resulting in compound 9 in 37% yield. Another More complex structures are obtained from pincer ligand 6

interesting feature of this complex is a free oligonitrile chain with PdCl₂[compound 6·(PdCl₂)₂] and from the tridentate

not used for coordination, which possibly can be used for ligand 7a in reactions with Ni(ClO₄)₂[compound

further complexation reactions.

7a·Ni(ClO₄)₂]. At present, we are interested in possible cata-

lytic properties of the coordination compounds in organic

synthesis.

Experimental Section

Materials and Methods: IR: Nicolet 5DXC. ¹H NMR: Bruker WM

300 (300.13 MHz), Bruker AMX 400 (400.13 MHz), Varian IN-

OVA 500 (499.8 MHz) and Varian Unity 600 (599.86 MHz); in-

ternal reference tetramethylsilane. ¹³C NMR: Bruker WM 300

(75.47 MHz), Bruker AMX 400 (100.61 MHz), Varian INOVA 500

(125.7 MHz) and Varian Unity 600 (150.84 MHz); internal refer-

ence solvent. CHN elemental analysis: Elementar Vario El III.

Melting points are uncorrected. All solvents were rigorously dried

by standard methods. When necessary, the experiments were car-

ried out with complete exclusion of moisture (argon, septum-sy-

ringe technique) in glassware that had been thoroughly dried by

repeated heating under argon and subsequent evacuation.

Scheme 12.

2,2Ј,2ЈЈ-(1,3,5-Phenylene)tris[4,6-bis(diisopropylamino)-1-oxa-3,5-di-

azinium] Tripentachlorostannate (1d): According to the procedure

described by Tashtoush and Al-Talib^[11]2b was prepared from tri-

mesic trichloride (2.66 g, 10.0 mmol), diisopropylcyanamide

(7.60 g, 60.0 mmol) and tin tetrachloride (2.4 mL, 30.0 mmol).

Yield: 14.87 g (8.3 mmol, 83 %, ref.^[11]87 %), orange solid, m.p.

184 °C (ref.^[11]187–189 °C).

X -ray C r y st a l S tr u c t u re A n a l y s i s o f 1 d : ^{[ 1 3 ]}For mu la

C₅₁H₈₇N₁₂O₃·3SnCl₅OH₂·CH₃CN, M = 1899.25, orange crystal

0.20ϫ0.20ϫ0.15 mm, a = 49.978(1), b = 9.972(1), c = 17.696(1) Å,

V = 8819.3(10) Å³, ρ_calcd.= 1.430 gcm^–3, µ = 1.343 mm^–1, empirical

absorption correction (0.775ՅTՅ0.824), Z = 4, orthorhombic,

space group Pnma (No. 62), λ = 0.71073 Å, T = 198(2) K, ω and

φ scans, 60198 reflections collected (Ϯh, Ϯ k, Ϯl), [(sinθ)/λ] =

0.67 Å^–1, 10946 independent (R_int= 0.044) and 8289 observed re-

Figure 11. Molecular structure of 9 in the solid state.

flections [I Ն 2 σ(I)], 499 refined parameters, R = 0.059, wR²

=

0.211, max./min. residual electron density 2.32/–1.08 eÅ^–3, the re-

maining density (probably disordered acetonitrile) could not be de-

scribed in a chemically meaningful way, hydrogen atoms calculated

and refined as riding atoms.

Conclusions

We have developed two alternative synthetic pathways for

the synthesis of branched bis- and tris(armed) oligonitrile

compounds. They are both based on nucleophilic ring

opening reactions of 1-oxa-3,5-diazinium salts. Thus, on

one hand reactions of bis- and tris(1-oxa-3,5-diazinium)

salts 1 with n-propylamine lead to the bis- and tris(armed)

oligonitrile derivatives 3 and 8 with secondary amino

groups in the side chain. On the other hand, treatment of

simple 1-oxa-3,5-diazinium salts 2 with primary and sec-

ondary di- and triamines provides access to the bis- and

2,4,6-Tris(4-bromophenyl)-1-oxa-3,5-diazinium Pentachlorostannate

(2b): In analogy to the procedure described by Tashtoush and Al-

Talib^[10]2b was prepared from 4-bromobenzoic chloride (32.10 g,

147 mmol), 4-bromobenzonitrile (53.30 g, 294 mmol) and tin tetra-

chloride (17.2 mL, 147 mmol). Yield: 111.79 g (134.0 mmol, 91%),

yellow solid, m.p. 195 °C. IR (KBr): ν = 3085 (w, CH_arom.), 1733

˜

(m, C=O), 1647 (m, C=N), 1614 (m, C=N), 1585 (s, C=C), 1571

(s, C=C), 1544 (m), 1490 (m), 1465 (m), 1446 (m), 1419 (m), 1396

(m), 1375 (m), 1332 (m), 1299 (m), 1224 (m), 1174 (m), 1114 (w),

tris(armed) oligonitriles 4, 5 and 7. 2,6-Diaminopyridine 1066 (m), 1004 (m), 935 (w), 835 (w), 792 (m), 748 (w), 723 (w), 661

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Multivalent 1-Oxa-3,5,7-triazahepta-1,3,5-trienes

(w), 644 (w), 622 (w) cm^–1. C₂₁H₁₂Br₃Cl₅N₂OSn (844.00): calcd. C

29.88, H 1.43, N 3.32; found C 30.14, H 1.68, N 3.21.

uct was purified by column chromatography with tert-butyl methyl

ether as eluent. Yield: 6.21 g (11.0 mmol, 37%), colourless solid,

m.p. 138 °C. R_f= 0.15 (tert-butyl methyl ether). ¹H NMR

(300.13 MHz, CDCl₃): δ = 0.89–0.94 (m, 6 H, NCH₂CH₂CH₃),

1.25 (br., 8 H, CH₂), 1.48 (br., 4 H, CH₂), 1.50–1.63 (m, 4 H,

NCH₂CH₂CH₃), 2.25–2.30 (br., 4 H, CH₂), 2.95 (br., 24 H, NCH₃),

3.20 (br., 4 H, NCH₂CH₂CH₃), 5.46 (br., 2 H, NH) ppm. ¹³C NMR

(75.47 MHz, CDCl₃): δ = 11.3 (NCH₂CH₂CH₃), 22.2, 26.5, 28.9,

29.1, 33.1, 37.1, 43.1 (CH₂, NCH₃, NCH₂CH₂CH₃), 160.2, 161.3

1-Oxa-3,5-diazahexatrienes 2–5. General Procedure: A suspension

of the 1-oxa-3,5-diazinium salt^[1,10,12]in dry dichloromethane was

treated with the respective amine at 0 °C. The reaction mixture was

warmed slowly to room temperature and was then stirred over-

night. The next day, the resulting solution was washed with sodium

hydroxide solution, and the aqueous layer was extracted three times

with dichloromethane. The combined organic layers were dried

with potassium sulfate, and the solvent was removed in vacuo. The

crude product was purified by column chromatography or

recrystallisation.

(CN), 163.2 (CO) ppm. IR (KBr): ν = 3239 (m, NH), 2936 (m,

˜

CH_aliph.), 2893 (m, CH_aliph.), 2852 (w, CH_aliph.), 1623 (s, C=O),

1606 (s, C=N), 1555 (s), 1523 (s), 1468 (s), 1441 (s), 1385 (s), 1312

(s), 1289 (m), 1182 (m), 1176 (m), 1140 (m), 1082 (w), 1027 (m),

929 (w), 874 (w), 817 (w), 780 (w), 746 (w), 667 (w), 656 (w), 548

(w), 482 (w) cm^–1. MS (EI, 70 eV): m/z (%) = 474 (8) [M –

2 NMe₂]⁺, 431 (5) [474 – Pr]⁺, 389 (1) [431 – Pr]⁺, 362 (2), 320 (11),

279 (63), 223 (16), 209 (100), 154 (42), 114 (11), 71 (31).

C₂₈H₅₆N₁₀O₂(564.81): calcd. C 59.54, H 9.99, N 24.80; found C

59.38, H 9.94, N 24.68.

1,4-Bis[3,5-bis(diisopropylamino)-1-propylamino-6-oxa-2,4-diaza-

1,3,5-hexatrienyl]benzene (3a): From 2,2Ј-(1,4-phenylene)bis[4,6-

bis(diisopropylamino)-1-oxa-3,5-diazinium] dipentachlorostannate

(1a)^[10](4.52 g, 3.7 mmol) and n-propylamine (1.5 mL, 14.8 mmol).

The crude product was purified by column chromatography with

tert-butyl methyl ether as eluent. Yield: 2.21 g (2.9 mmol, 79%),

colourless solid, m.p. 154 °C. R_f= 0.06 (tert-butyl methyl ether).

¹H NMR (300.13 MHz, CDCl₃): δ = 1.05–1.10 (br., 18 H,

NCH₂CH₂CH₃/NCHCH₃), 1.32–1.42 (br., 36 H, NCHCH₃) 1.73–

1 . 8 0 ( b r. , 4 H , N C H ₂C H ₂C H ₃) , 3 . 4 9– 3 . 5 5 ( b r. , 4 H ,

NCH₂CH₂CH₃), 3.74–4.17 (br., 8 H, NCHCH₃), 5.03 (br., 2 H,

NH), 7.67 (s, 4 H, CH_arom.) ppm. ¹³C NMR (75.47 MHz, CDCl₃):

δ = 11.2, 20.9, 22.6, 44.1, 46.1 (br., CH_aliph.), 127.3 (CH_arom.), 136.8

N,NЈ-Bis(3,5-dimorpholino-1-phenyl-2,4-diaza-6-oxa-1,3,5-hexatri-

enyl)ethylenediamine (4a): From a solution of 2-(diethylamino)-4,6-

diphenyl-1,3,5-oxadiazinium pentachlorostannate (2a)^[1](6.07 g,

10.0 mmol) in 40 mL of dry dichloromethane and ethylenediamine

(0.30 g, 5.0 mmol). Purification by medium-pressure chromatog-

raphy (cyclohexane/ethyl acetate, 2:1 + 5% of triethylamine) and

recrystallisation from acetone. Yield: 2.18 g (3.3 mmol, 65 %),

colourless solid, m.p. 208 °C. R_f= 0.36 (cyclohexane/ethyl acetate,

(i-C_arom.), 156.8, 158.1 (CN), 161.9 (CO) ppm. IR (KBr): ν = 3298

˜

(m, NH), 3066 (s, CH_arom.), 2964 (s, CH_aliph.), 2927 (s, CH_aliph.),

2873 (s, CH_aliph.), 1623 (vs, C=O/C=N), 1569 (vs, C=C), 1519 (s),

1467 (s), 1438 (s), 1431 (s), 1369 (s), 1313 (s), 1220 (s), 1149 (m),

1130 (m), 1055 (sh), 1041 (m), 966 (w), 919 (w), 885 (w), 860 (w),

846 (w), 781 (w), 761 (w), 653 (w), 611 (w), 580 (w), 511 (w) cm^–1.

MS (EI, 70 eV): m/z (%) = 753 (1) [M]⁺, 653 (2) [M – NiPr₂]⁺, 551

(7) [M – 2 NiPr₂]⁺, 507 (2), 400 (11), 340 (80), 296 (9), 171 (9),

128 (30) [iPr₂NCO]⁺, 100 (20) [iPr₂N]⁺, 86 (100), 58 (20) [NHPr]⁺.

C₄₂H₇₆N₁₀O₂(753.13): calcd. C 66.98, H 10.17, N 18.60; found C

67.21, H 10.02, N 18.48.

1

2:1 + 5% of triethylamine). H NMR (400.13 MHz, CDCl₃): δ =

0.85–0.92 (m, 12 H, CH₃), 1.86 (br., 1 H, NH), 2.83 [s (br.), 4 H,

3

NCH₂CH₃], 2.96 (q, J = 7.2 Hz, 4 H, NHCH₂), 3.49 [s (br.), 4 H,

NCH₂CH₃], 7.18–7.39 (m, 12 H, CH_arom.), 7.55–7.57 (m, 4 H, o-

CH_arom.), 8.03–8.05 (m, 4 H, o-CH_arom.) ppm. ¹³C NMR

(100.61 MHz, CDCl₃): δ = 13.3, 13.5 (CH₃), 38.9 (NCH₂), 39.7,

41.5 (NCH₂CH₃), 127.6, 127.7, 128.1, 128.6, 130.1, 130.3,

(CH_arom.), 134.3, 137.8 (i-C_arom.), 159.8 163.4 (CN), 163.8 (CO)

ppm. IR (KBr): ν = 3340 (m, NH), 3062 (w, CH_arom.), 3026 (w,

˜

CH_arom), 2972 (m, CH_aliph.), 2925 (m, CH_aliph.), 2868 (w, CH_aliph.),

1598 (vs, C=O), 1564 (vs, C=C), 1539 (vs, C=C), 1490 (m, C=C),

1463 (s), 1452 (s), 1429 (s), 1415 (s), 1375 (s), 1359 (s), 1313 (s),

1299 (m), 1272 (vs), 1224 (m), 1193 (w), 1159 (m), 1130 (m), 1099

(w), 1080 (w), 1070 (w), 1047 (w), 896 (m), 846 (w), 810 (w), 773

(m), 707 (m), 692 (s), 663 (m) cm^–1. MS (ESI): m/z = 671 [M +

H]⁺, 379 [C₂₃H₃₀N₄OH]⁺. HR ESI MS [M + H]⁺: calcd. 671.3816;

found 671.3817. C₄₀H₄₆N₈O₂(670.37): calcd. C 71.62, H 6.91, N

16.70; found C 71.41, H 6.91, N 16.32.

1,4-Bis[3,5-bis(dimethylamino)-1-propylamino-6-oxa-2,4-diaza-

1,3,5-hexatrienyl]butane (3b): From 2,2Ј-(1,4-butylene)bis[4,6-

bis(dimethylamino)-1-oxa-3,5-diazinium] dihexachloroantimonate

(1b)^[10](4.41 g, 4.2 mmol) and n-propylamine (1.5 mL, 16.8 mmol).

The crude product was purified by column chromatography with

acetone with 3% triethylamine as eluent. Yield: 1.15 g (2.3 mmol,

50%), colourless solid, m.p. 173 °C. R_f= 0.14 (acetone with 3%

triethylamine). ¹H NMR (300.13 MHz, CDCl₃): δ = 0.80–0.85 (br.,

6 H, NCH₂CH₂CH₃), 1.44–1.51 (m, 8 H, NCH₂CH₂CH₃/

CH₂CH₂CH₂CH₂), 2.19–2.24 (br., 4 H, CH₂CH₂CH₂CH₂), 2.85

(br., 24 H, NCH₃), 3.07–3.12 (br., 4 H, NCH₂CH₂CH₃), 5.73 (br.,

2 H, NH) ppm. ¹³C NMR (75.47 MHz, CDCl₃): δ = 11.3, 22.2,

25.4, 29.1, 32.1, 37.0, 43.0 (br., CH_aliph.), 159.8, 160.1 (CN), 164.0

N,NЈ-Bis[5-(diethylamino)-1,3-diphenyl-2,4-diaza-6-oxa-1,3,5-hexa-

trienyl]-1,3-propylenediamine (4b): From 2-(diethylamino)-4,6-di-

phenyl-1,3,5-oxadiazinium pentachlorostannate (2a)^[1](6.07 g,

10.0 mmol) in dry dichloromethane (40 mL) and 1,3-diaminopro-

pane (0.37 g, 5.0 mmol). The crude solid product was purified by

recrystallisation from acetone. Yield: 1.71 g (2.5 mmol, 50 %),

(CO) ppm. IR (KBr): ν = 3243 (m, NH), 2927 (m, CH_aliph.), 2886

˜

(m, CH_aliph.), 2848 (w, CH_aliph.), 1619 (s, C=O), 1610 (s, C=N),

1552 (s), 1521 (s), 1475 (s), 1434 (s), 1386 (s), 1342 (s), 1270 (m),

1193 (m), 1176 (m), 1139 (m), 1079 (w), 1033 (m), 921 (w), 883 (w),

815 (w), 779 (w), 730 (w), 663 (w), 636 (w), 553 (w), 482 (w) cm^–1.

MS (EI, 70 eV): m/z (%) = 508 (5) [M]⁺, 464 (4) [M – NMe₂]⁺, 419

(64) [M – 2 NMe₂]⁺, 360 (6), 306 (17), 264 (21), 223 (23), 210 (17),

193 (15), 139 (13), 114 (19), 72 (100). C₂₄H₄₈N₁₀O₂(508.71): calcd.

C 56.67, H 9.51, N 27.53; found C 56.61, H 9.38, N 27.47.

1

colourless solid, m.p. 148 °C. H NMR (400.13 MHz, CDCl₃): δ =

1.01 (t, ³J = 6.6 Hz, 6 H, CH₃), 1.09 (t, ³J = 7.8 Hz, 6 H, CH₃),

2.23 (br., 2 H, CH₂), 2.78 (q, ³J = 7.1 Hz, 4 H, NCH₂CH₃), 3.06

(q, ³J = 7.8 Hz, 4 H, NCH₂CH₃), 3.78 (br., 4 H, NCH₂), 7.03–7.42

(m, 12 H, CH_arom.), 7.40–7.43 (m, 4 H, o-CH_arom.), 7.93–7.96 (m,

4 H, o-CH_arom.) ppm. ¹³C NMR (100.63 MHz, CDCl₃): δ = 13.8

(CH₃), 26.8 (CH₂), 39.9, 40.6, 41.5 (NCH₂), 127.8, 128.2, 128.6,

130.1, 130.3, (CH_arom.), 135.0, 137.9 (i-C_arom.), 158.3, 163.1 (CN),

1,8-Bis[3,5-bis(dimethylamino)-1-propylamino-6-oxa-2,4-diaza-

1,3,5-hexatrienyl]octane (3c): From 2,2Ј-(1,8-octylene)bis[4,6-bis(di-

methylamino)-1-oxa-3,5-diazinium] dihexachloroantimonate

(1c)^[10]and n-propylamine (9.8 mL, 120.0 mmol). The crude prod-

164.0 (CO) ppm. IR (KBr): ν = 3264 (br., NH), 3064 (w, CH_arom.),

˜

2969 (m, CH_aliph.), 2930 (m, CH_aliph.), 1596 (br., C=O), 1573 (br.,

C=N), 1534 (br., C=N), 1489 (w, C=C), 1460 (br), 1418 (m), 1376

(s), 1313 (m), 1276 (vs), 1226 (w), 1154 (w), 1092 (w), 1023 (w),

Eur. J. Org. Chem. 2008, 5740–5754

www.eurjoc.org

5747

J.-B. Greving, H. Behrens, R. Fröhlich, E.-U. Würthwein

FULL PAPER

978 (w), 907 (w), 811 (w), 773 (m), 693 (s), 659 (w), 605 (w), 537

1027 (w), 953 (w), 908 (w), 858 (w), 775 (s), 711 (m), 695 (s), 658

(w) cm^–1. MS (EI, 70 eV): m/z (%) = 684 (8) [M]⁺, 613 (15) [M –

(w), 604 (w), 539 (w) cm^–1. MS (ESI): m/z = 794 [M + K]⁺, 777

NEt₂]⁺, 539 (6) [M – 2(NEt₂)]⁺, 290 (32) [C₁₈H₁₆N₃O]⁺, 213 (5.8) [M + Na]⁺, 755 [M + H]⁺, 682 [(M + H) – NEt₂]⁺, 609 [(M + H) –

[C₁₂H₁₁N₃O]⁺. C₄₁H₄₈N₈O₂(684.88): calcd. C 71.90, H 7.06, N

16.36; found C 71.59, H 6.80, N 16.32.

2 (NEt₂)]⁺, 377. MS (EI, 70 eV): m/z (%) = 608 (13), 403 (14), 360

(25), 346 (22), 249 (43), 159 (11), 103 (100). C₄₄H₅₄N₈O₂(754.46):

calcd. C 73.18, H 7.74, N 14.84; found C 72.64, H 7.47, N 14.73.

X-ray Crystal Structure Analysis of 4b:^[13]Formula C₄₁H₄₈N₈O₂, M

= 684.87, colourless crystal 0.30ϫ0.20ϫ0.20 mm, a = 17.960(1),

b = 13.800(1), c = 16.222(1) Å, β = 107.80(1)°, V = 3828.1(4) Å³,

ρ_calcd.= 1.188 gcm^–3, µ = 0.597 mm^–1, empirical absorption correc-

tion (0.841ՅTՅ0.890), Z = 4, monoclinic, space group Cc (No.

9), λ = 1.54178 Å, T = 223 K, ω/2θ scans, 4036 reflections collected

(Ϯh, Ϯk, Ϯl), [(sinθ)/λ] = 0.62 Å^–1, 4036 independent and 3826

observed reflections [IՆ2σ(I)], 478 refined parameters, R = 0.036,

wR²= 0.119, max./min. residual electron density 0.23/–0.20 eÅ^–3,

Flack parameter –0.3(3), hydrogen atoms at N from difference Fou-

rier calculations, others calculated and all refined as riding atoms.

N,NЈ-Bis[5-(diethylamino)-1,3-diphenyl-2,4-diaza-6-oxa-1,3,5-hexa-

trienyl]-m-xylylenediamine (4e): From 2-(diethylamino)-4,6-di-

phenyl-1,3,5-oxadiazinium pentachlorostannate (2a)^[1](3.6 g,

6.0 mmol) in dry dichloromethane (30 mL) and m-xylylenediamine

(0.4 g, 3.0 mmol). The crude solid product was purified by

recrystallisation from acetone. Yield: 0.8 g (1.1 mol, 37%), colour-

less solid, m.p. 74 °C. ¹H NMR (300.13 MHz, CDCl₃): δ = 1.01 (t,

3

³J = 11.7 Hz, 12 H, CH₃), 3.10 (q, J = 11.7 Hz, 8 H, CH₂), 4.71

3

(d, J = 2.7 Hz, 4 H, CH₂), 6.10 (s, 2 H, NH), 7.10–7.81 (m, 24 H,

CH_arom.) ppm. ¹³C NMR (75.47 MHz, CDCl₃): δ = 13.4, 13.9

(CH₃), 39.9, 41.7 (NCH₂), 46.1 (Aryl-CH₂), 126.7, 127.4, 127.5,

127.7, 128.4, 128.5, 128.6 (C_arom.), 130.2, 131.8 (p-C_arom.), 134.9,

137.4, 138.9 (i-C_arom.), 158.1, 162.9 (CN), 164.1 (CO) ppm. IR

N,NЈ-Bis[5-(diethylamino)-1,3-diphenyl-2,4-diaza-6-oxa-1,3,5-hexa-

trienyl]-1,6-hexylenediamine (4c): From a solution of 2-(dieth-

ylamino)-4,6-diphenyl-1,3,5-oxadiazinium pentachlorostannate

(2a)^[1](6.07 g, 10.0 mmol) in dry dichloromethane and 1,6-hexane-

diamine (0.64 g, 5 mmol). The resultant precipitate was purified by

recrystallisation from hot acetone. Yield: 1.23 g (1.7 mmol, 34%),

(KBr): ν = 3275 (m, NH), 3058 (m, CH_arom.), 2970 (m, CH_aliph.),

˜

2927 (s, CH_aliph.), 1612 (vs, C=O), 1573 (s, C=N), 1529 (s, C=N),

1490 (m, C=C), 1460 (s, C=C), 1454 (s, C=C), 1375 (s), 1311 (s),

1274 (s), 1153 (m), 1099 (m), 900 (w), 775 (m), 694 (s) cm^–1. MS

(ESI): m/z = 769 [M + Na]⁺, 747 [M + H], 674.3 [(M + H) –

NEt₂]⁺. C₄₆H₅₀N₈O₂(746.41). calcd. C 73.97 H 6.75 N 15.00;

found C 73.56 H 6.61 N 14.98.

1

colourless solid, m.p. 164 °C. H NMR (400.13 MHz, CDCl₃): δ =

0.98 (t, ³J = 7.6 Hz, 6 H, CH₃), 1.09 (t, ³J = 6.8 Hz, 6 H, CH₃),

1.46 (br., 4 H, CH₂), 1.71 (br., 4 H, CH₂), 3.04 (q, ³J = 7.1 Hz, 4 H,

NCH₂CH₃), 3.29 (q, ³J = 6.4 Hz, 4 H, NCH₂CH₃), 3.47 [q, ³J =

6.9 Hz, 4 H, NCH_2(hexane)], 5.38 (br., NH), 7.20–7.29 (m, 12 H, N,NЈ-Bis[5-(diethylamino)-1,3-diphenyl-2,4-diaza-6-oxa-1,3,5-hexa-

CH_arom.), 7.51–7.53 (m, 4 H, o-CH_arom.), 7.79–7.81 (m, J = 7.6 Hz,

4 H, o-CH_arom.) ppm. ¹³C NMR (100.63 MHz, CDCl₃): δ = 13.5,

13.9 (CH₃), 26.8, 27.9, 28.8 (CH₂), 40.0, 41.8, 42.4 (NCH₂), 127.5,

1 127.8, 128.4, 128.4, 130.2 (CH_arom.), 135.3, 137.5 (i-C_arom.), 158.3,

trienyl]-p-xylylenediamine (4f): From 2-(diethylamino)-4,6-di-

phenyl-1,3,5-oxadiazinium pentachlorostannate (2a)^[1](6.07 g,

10.0 mmol) in dry dichloromethane (40 mL) and p-xylylenediamine

(0.67 g, 5.0 mmol). The crude solid product was purified by

162.9 (CN), 164.1 (CO) ppm. IR (KBr): ν = 3253 (br., NH), 3056

recrystallisation from acetone. Yield: 1.66 g (2.3 mmol, 46 %),

˜

1

(w, CH_arom.), 2970 (s, CH_aliph.), 2931 (s, CH_aliph.), 2871 (w, colourless solid, m.p. 138 °C. H NMR (300.13 MHz, CDCl₃): δ =

CH_aliph.), 1617 (br., C=O), 1560 (br., C=N), 1540 (br., C=N), 1490 0.96 (t, ³J = 7.6 Hz, 6 H, CH₃), 1.05 (t, ³J = 6.8 Hz, 6 H, CH₃),

3

(m, C=C), 1468 (s), 1425 (br), 1377 (s), 1351 (w), 1332 (w), 1311 3.00 (q, J = 7.6 Hz, 4 H, NCH₂CH₃), 3.26 (q, J = 6.8 Hz, 4 H,

(s) 1276 (vs), 1231 (w), 1185 (w), 1152 (s), 1118 (w), 1106 (m), 1079

NCH₂CH₃), 4.55 (d, ³J = 7.12 Hz, 4 H, NCH₂), 7.12–7.30 (m,

(w), 1055 (m), 1022 (m), 978 (w), 959 (w), 923 (w), 899 (s), 849 (w), 12 H, CH_arom.), 7.46 (br., 8 H, o-CH_arom.), 7.58–7.61 (m, 4 H,

809 (m), 793 (w), 780 (s), 725 (w), 695 (s), 661 (m), 618 (w), 607 CH_arom.) ppm. ¹³C NMR (75.47 MHz,CDCl₃): δ = 13.4, 13.9

(w), 570 (w) cm^–1. MS (ESI): m/z = 765 [M + K]⁺, 749 [M +

Na]⁺, 727 [M + H]⁺, 693 [(M + K) – NEt₂]⁺, 654 [(M + H) –

(CH₃), 38.7, 38.9, 39.2, 39.5, 39.8, 40.1, 40.4, 40.9, 44.6 (NCH₂),

127.6, 127.9, 129.9, 130.1 (CH_arom.), 134.7, 136.81, 137.9 (i-C_arom.),

NEt₂]⁺. MS (EI, 70 eV): m/z (%) = 580 (40), 318 (100), 274 (59), 157.9, 161.8 (CN), 163.4 (CO) ppm. IR (KBr): ν = 3420 (br., NH),

˜

234 (27), 159 (22), 103 (97), 56 (68). C₄₄H₅₄N₈O₂(726.44): calcd.

C 72.70, H 7.49, N 15.41; found C 72.55, H 7.39, N 15.40.

3059 (m, CH_arom.), 2972 (m, CH_aliph.), 2930 (m, CH_aliph.), 1613 (vs,

C=O), 1571 (m, C=N), 1536 (br., C=N), 1490 (w, C=C), 1468 (s),

1422 (m), 1376 (m), 1338 (w) 1275 (vs), 1224 (w), 1155 (m), 1097

(m), 1019 (w), 928 (w), 896 (w), 776 (m), 728 (w), 696 (s), 661 (w),

603 (w) cm^–1. MS (ESI): m/z = 785 [M + K]⁺, 769 [M + Na]⁺, 747

[M + H]⁺, 674 [(M + H) – NEt₂]⁺, 601 [(M + H) – 2 NEt₂]⁺. MS

(EI, 70 eV): m/z (%) = 329 (23), 262 (2), 250 (100), 183 (3), 147 (8),

104.1 (42), 80 (45). C₄₆H₅₀N₈O₂(746.41): calcd. C 73.97, H 6.75,

N 15.00; found C 73.72, H 6.55, N 15.06.

N,NЈ-Bis[5-(diethylamino)-1,3-diphenyl-2,4-diaza-6-oxa-1,3,5-hexa-

trienyl]-1,8-octylenediamine (4d): From 2-(diethylamino)-4,6-di-

phenyl-1,3,5-oxadiazinium pentachlorostannate (2a)^[1](6.07 g,

10.0 mmol) in dry dichloromethane (40 mL) and 1,8-octanediam-

ine (0.72 g, 5.0 mmol). The crude solid product was purified by

recrystallisation from acetone. Yield: 2.30 g (3.0 mmol, 60 %),

1

colourless solid, m.p. 185 °C. H NMR (300.13 MHz, CDCl₃): δ =

1.03 (t, ³J = 8.4 Hz, 6 H, CH₃), 1.14 (t, ³J = 7.1 Hz, 6 H, CH₃),

N,NЈ-Bis[5-(diethylamino)-1,3-diphenyl-2,4-diaza-6-oxa-1,3,5-hexa-

1.37 (br., 8 H, CH₂), 1.68 (br., 4 H, CH₂), 3.08 (q, ³J = 8.4 Hz, 4 H, trienyl]-1,4-cyclohexanediamine (4g): From a solution of 2-(dieth-

3

NCH₂CH₃), 3.33 (q, J = 9.2 Hz, 4 H, NCH₂CH₃), 3.46 [br., 4 H,

ylamino)-4,6-diphenyl-1,3,5-oxadiazinium pentachlorostannate

NCH_2(octane)], 5.19 (br., NH), 7.21–7.30 (m, 12 H, CH_arom.), 7.52– (2a)^[1](6.07 g, 10.0 mmol) in 40 mL of dry dichloromethane and

7.54 (m, 4 H, o-CH_arom.), 7.78–7.80 (m, 4 H, o-CH_arom.) ppm. ¹³C 1,4-trans-diaminocyclohexane (0.6 g, 5.0 mmol). The resultant pre-

NMR (75.47 MHz, CDCl₃): δ = 13.5, 13.9 (CH₃), 27.0, 29.0, 29.2

(CH₂), 40.7, 41.8, 42.6 (NCH₂), 127.5, 127.8, 128.4, 128.5, 130.2

(CH_arom.), 135.3, 137.4 (i-C_arom.), 158.3, 162.9 (CN), 164.2 (CO) (599.86 MHz, CDCl₃): δ = 1.04 (t, J = 7.1 Hz, 6 H, CH₃), 1.38 (t,

cipitate was purified by recrystallisation from hot acetone. Yield:

2.30 g (2.3 mol, 64 %), colourless solid, m.p. 211 °C. ¹H NMR

3

ppm. IR (KBr): ν = 3259 (br., NH), 3061 (m, CH_arom.), 2971 (m,

³J = 7.1 Hz, 6 H, CH₃), 1.38–1.41 (m, 4 H, CH₂), 2.35 (d, ³J =

˜

3

CH_aliph.), 2930 (s, CH_aliph.), 2856 (m, CH_aliph.), 1595 (vs, C=O),

1572 (br., C=N), 1533 (br., C=N), 1490 (m, C=C), 1458 (s), 1418

5.9 Hz, 4 H, CH₂), 3.04 (q, J = 7.1 Hz, 4 H, NCH₂CH₃), 3.31 (q,

³J = 7.1 Hz, 4 H, NCH₂CH₃), 3.89 [br., 2 H, NCH_{(cyclohexane)}], 5.11

(m), 1376 (m), 1315 (m) 1276 (vs), 1226 (w), 1156 (s), 1096 (m), (br., NH), 7.17–7.29 (m, 12 H, CH_arom.), 7.52–7.54 (m, 4 H, o-

5748

www.eurjoc.org

Eur. J. Org. Chem. 2008, 5740–5754

Multivalent 1-Oxa-3,5,7-triazahepta-1,3,5-trienes

CH_arom.), 7.65–7.78 (m, 4 H, o-CH_arom.) ppm. ¹³C NMR diazinium pentachlorostannate (2a)^[1](3.61 g, 6.0 mmol), 0.6 mL

(150.84 MHz, CDCl₃): δ = 13.5 (CH₃), 13.9 (CH₃), 31.1 (CH₂), (6.0 mmol) triethylamine and piperazine (0.26 g, 3.0 mmol) in

39.9 (NCH₂CH₃), 41.7 (NCH₂CH₃), 50.5 [NCH_{(cyclohexane)}], 127.4, 40 mL of dry dichloromethane. The crude solid product was puri-

127.7, 128.3, 128.3, 130.1, 130.1, (CH_arom.), 135.1, 137.1 (i-C_arom.),

fied by recrystallisation from acetone. Yield: 3.23 g (4.7 mmol,

157.4, 162.7 (CN), 164.2 (CO) ppm. IR (KBr): ν = 3259 (br., NH),

77 %), colourless solid, m.p. 231 °C. ¹H NMR (300.13 MHz,

˜

3

3061 (m, CH_arom.), 2967 (m, CH_aliph.), 2931 (s, CH_aliph.), 2868 (w,

CDCl₃): δ = 0.98–1.02 (t, J = 7.1 Hz, 6 H, NCH₃), 1.19–1.23 (t,

CH_aliph.), 1619 (br., C=O), 1558 (br., C=N), 1538 (br., C=N), 1490 ³J = 7.1 Hz, 6 H, NCH₃), 3.05–3.12 (q, J = 7.1 Hz, 4 H, NCH₃),

3

(m, C=C), 1447 (br), 1421 (s), 1376 (m), 1361 (m), 1315 (vs), 1274

(vs), 1237 (w), 1154 (vs), 1116 (s), 951 (m), 925 (m), 877 (m), 792

(w), 777 (vs), 695 (vs), 639 (w), 603 (w), 509 (w) cm^–1. MS (ESI):

m/z = 764 [M + K]⁺, 747 [M + Na]⁺, 725 [M + H]⁺, 652 [(M +

3.38–3.44 (q, J = 7.1 Hz, 4 H, NCH₃), 3.57 (br., 8 H, CH₂), 7.17–

7.39 (m, 16 H, CH_arom.), 7.64–7.66 (d, ³J = 6.9 Hz, 4 H, o-CH_arom.

)

ppm. ¹³C NMR (75.47 MHz, CDCl₃): δ = 13.9, 14.4 (NCH₂CH₃),

40.7, 42.3 (NCH₂), 46.5–46.8 (br., CH₂), 128.1, 128.6, 130.1, 130.6,

H) – NEt₂]⁺, 379, 249. MS (EI, 70 eV): m/z (%): 329 (23), 262 (2), 133.5 (C_arom.), 137.7 (i-C_arom.), 160.6, 163.4 (CN), 164.3 (CO) ppm.

250 (100), 183 (3), 147 (8), 104 (42), 80 (45). C₄₄H₅₂N₈O₂(724.94): IR (KBr): ν = 3058 (m, CH_arom.), 3024 (m, CH_arom.), 2970 (m,

˜

calcd. C 72.90, H 7.23, N 15.46; found C 72.84, H 7.01, N 15.49.

CH_aliph.), 2931 (m, CH_aliph.), 2871 (m, CH_aliph.), 1639 (vs, C=O),

1610 (vs, C=N), 1593 (vs, C=N), 1573 (vs, C=N), 1492 (m, C=C),

1438 (s), 1419 (vs), 1365 (s), 1313 (s), 1265 (vs), 1245 (vs), 1164

(m), 1153 (s), 1082 (s), 1008 (s), 974 (m), 943 (m), 779 (s), 732 (m),

698 (s) cm^–1. MS (ESI): m/z (%) = 719 [M + Na]⁺, 697 [M + H]⁺.

C₄₂H₄₈N₈O₂(696.39): calcd. C 72.39, H 6.94, N 16.08; found C

72.32, H 6.85, N 16.07.

X-ray Crystal Structure Analysis of 4g:^[13]Formula C₄₄H₅₂N₈O₂·

3C₃H₆O, M = 841.09, colourless crystal 0.35ϫ0.30ϫ0.10 mm, a

= 11.733(1), b = 12.413(1), c = 16.363(1) Å, β = 98.43(1)°, V =

2357.4(4) Å³, ρ_calcd.= 1.185 gcm^–3, µ = 0.605 mm^–1, empirical ab-

sorption correction (0.816ՅTՅ0.942), Z = 2, monoclinic, space

group P2₁/c (No. 14), λ = 1.54178 Å, T = 223 K, ω/2θ scans, 9715

reflections collected (Ϯh, Ϯk, Ϯl), [(sinθ)/λ] = 0.62 Å^–1, 4808 inde-

pendent (R_int= 0.031) and 3813 observed reflections [IՆ2σ(I)],

288 refined parameters, R = 0.042, wR²= 0.124, max./min. residual

electron density 0.26/–0.22 eÅ^–3, hydrogen atom at N7 from differ-

ence Fourier calculations, other calculated and all refined as riding

atoms.

N,NЈ-Bis[5-(diethylamino)-1,3-phenyl-2,4-diaza-6-oxa-1,3,5-hexatri-

enyl]-N,NЈ-dimethylethylenediamine (5b): From 2-(diethylamino)-

4,6-diphenyl-1,3,5-oxadiazinium pentachlorostannate (2a)^[1]

(3.61 g, 6.0 mmol) in dry dichloromethane (30 mL), 0.6 mL

(6.0 mmol) triethylamine and N,NЈ-dimethylethylenediamine

(0.26 g, 3 mmol). The crude solid product was purified by column

chromatography (ethyl acetate/cyclohexane, 1:2 + 5 % triethyl-

amine) following recrystallisation from acetone. Yield: 1.67 g

(2.4 mmol, 79%), colourless solid. m.p. 107 °C. R_f= 0.08 (cyclo-

hexane/ethyl acetate, 2:1 with 5 % triethylamine). ¹H NMR

(300.13 MHz, CDCl₃): δ = 0.98–1.02 (t, ³J = 7.1 Hz, 6 H, CH₃),

1.19–1.23 (t, ³J = 7.1 Hz, 6 H, CH₃), 3.05–3.12 (q, ³J = 7.1 Hz,

4 H, NCH₂), 3.38–3.44 (q, ³J = 7.1 Hz, 4 H, NCH₂), 3.57 [br., 8 H,

NCH_2(pip.)], 7.17–7.39 (m, 16 H, CH_arom.), 7.64–7.66 (d, ³J = 6.9 Hz

4 H, p-CH_arom.) ppm. ¹³C NMR (75.47 MHz, CDCl₃): δ = 13.3,

N,NЈ-Bis[5-(diethylamino)-1,3-diphenyl-2,4-diaza-6-oxa-1,3,5-hexa-

trienyl]-1,2-trans-cyclohexanediamine (4h): To a solution of 2-(di-

ethylamino)-4,6-diphenyl-1,3,5-oxadiazinium pentachlorostannate

(2a)^[1](3.61 g, 6.0 mmol) in dry dichloromethane trans-1,2-diami-

nocyclohexane (0.32 g, 3.0 mmol) was added. The resultant precipi-

tate was purified by recrystallisation from hot aceton. Yield: 1.27 g

(1.3 mmol, 46 %), colourless solid, m.p. 175 °C. ¹H NMR

3

(300.13 MHz, CDCl₃): δ = 0.86 (t, J = 7.1 Hz, 6 H, NCH₂CH₃),

0.99 (t, ³J = 7.1 Hz, 6 H, NCH₂CH₃), 0.99 (br., 2 H, CH₂), 1.25,

1.38, 1.52 (br., 6 H, CH₂), 3.05 (m, 8 H, NCH₂), 4.03 (s, 2 H, NCH) 13.5 (CH₃), 38.9 (NCH₃), 39.7, 41.5 (NCH₂CH₃), 45.7 (NCH₂),

7.22–7.42 (m, 12 H, CH_arom.), 7.73–7.86 (m, 4 H, CH_arom.), 7.98–

127.6, 128.1, 128.6, 130.1, 130.3 (C_arom.), 134.3, 137.84 (i-C_arom.),

8.00 (m, 4 H, o-CH_arom.) ppm. ¹³C NMR (75.47 MHz, CDCl₃): δ

159.8, 163.4 (CN), 163.8 (CO) ppm. IR (KBr): ν = 3062 (m,

˜

= 13.5, 13.9 (CH₃), 24.7, 33.0 (CH₂), 39.7, 41.5 (NCH₂), 55.1 CH_arom.), 3028 (w, CH_arom.), 2972 (s, CH_aliph.), 2925 (s, CH_aliph.),

(NCH), 127.9, 128.2, 128.5, 130.3, 130.6 (C_arom.), 135.4, 136.5 (i- 2868 (m, CH_aliph.), 1600 (vs, C=O), 1566 (vs, C=C), 1565 (vs, C=C),

C_arom.), 156.1, 162.3 (CN), 164.7 (CO) ppm. IR (KBr): ν = 3298 1539 (vs, C=C), 1490 (s, C=C), 1463 (vs), 1452 (vs), 1429 (vs), 1415

˜

(s, NH), 3060 (m, CH_arom.), 2976 (m, CH_aliph.), 2931 (s, CH_aliph.), (vs, C=C), 1377 (vs), 1313 (vs), 1299 (s), 1272 (vs), 1224 (m), 1193

2858 (m, CH_aliph.), 1654 (vs, C=O), 1604 (vs, C=N), 1548 (vs,

(m), 1154 (m), 1130 (s), 1099 (m), 1080 (m), 1047 (s) 1026 (m), 1016

C=N), 1502 (vs, C=C), 1490 (s, C=C), 1448 (s, C=C), 1417 (s), (m), 952 (w), 927 (w), 896 (s), 846 (m), 810 (m), 773 (s), 742 (w),

1377 (s), 1326 (s), 1271 (vs), 1224 (m), 1190 (m), 1157 (s), 1101 (m), 707 (vs), 692 (vs), 663 (s) cm^–1. MS (ESI): m/z = 721 [M + Na]⁺,

1072 (m), 1026 (m), 927 (m), 900 (m), 877 (m), 755 (m), 694 (s)

699 [M + H]⁺. C₄₂H₅₀N₈O₂(698.41): calcd. C 72.18, H 7.21, N

cm^–1. MS (ESI): m/z (%) = 747 [M + Na]⁺, 725 [M + H]⁺, 182. 16.03; found C 72.20, H 6.78, N 16.18.

C₄₄H₅₂N₈O₂(724.42): calcd. C 72.90, H 7.23, N 15.46; found C

73.82, H 7.13, N 15.49.

X-ray Crystal Structure Analysis of 4h:^[13]Formula C₄₄H₅₂N₈O₂, M

N,NЈ-Diethyl-N,NЈ-bis[5-(diethylamino)-1,3-phenyl-2,4-diaza-6-oxa-

1,3,5-hexatrienyl]-p-xylylenediamine (5c): From a solution of 2-(di-

ethylamino)-4,6-diphenyl-1,3,5-oxadiazinium pentachlorostannate

(2a)^[1](3.61 g, 6.0 mmol) in dry dichloromethane, 0.6 mL

(6.0 mmol) triethylamine and N,NЈ-diethyl-p-xylylenediamine

(0.58 g, 3.0 mmol). The crude product was purified by column

chromatography (cyclohexane/ethyl acetate, 5:1 with 5% triethyl-

amine), and the resultant precipitate was purified by recrystalli-

sation from hot acetone. Yield: 1.23 g (1.5 mmol, 50%), colourless

solid, m.p. 138 °C. R_f= 0.03 (cyclohexane/ethyl acetate, 5:1 with

= 724.94, light yellow crystal 0.25ϫ0.25ϫ0.15 mm, a = 10.138(1),

b = 16.362(1), c = 23.918(1) Å, V = 3967.5(5) Å³, ρ_calcd.

=

1.214 g cm^–3, µ = 0.077 mm^–1, empirical absorption correction

(0.981ՅTՅ0.989), Z = 4, orthorhombic, space group P2₁2₁2₁

(No. 19), λ = 0.71073 Å, T = 198 K, ω and φ scans, 16673 reflec-

tions collected (Ϯh, Ϯk, Ϯl), [(sinθ)/λ] = 0.67 Å^–1, 9548 indepen-

dent (R_int= 0.037) and 5926 observed reflections [IՆ2σ(I)], 499

refined parameters, R = 0.060, wR²= 0.118, max./min. residual

electron density 0.21/–0.17 eÅ^–3, Flack parameter –0.3(12), hydro-

gen atoms at N4 from difference Fourier calculations, others calcu-

lated and all refined as riding atoms.

1

5% of triethylamine). H NMR (300.13 MHz, CHCl₃): δ = 1.02–

3

1.24 (m, 18 H, NCH₂CH₃), 3.16 (q, J = 6.9 Hz, 6 H, NCH₂), 3.44

(q, ³J = 6.9 Hz, 6 H, NCH₂), 4.56–4.84 (br., 4 H, PhCH₂) 7.14–

7.42 (br., 24 H, CH_arom.) ppm. ¹³C NMR (75.47 MHz, CHCl₃): δ

= 13.5, 13.9 (CH₃), 40.2, 42.0 (NCH₂), 127.5, 127.9, 128.0, 128.1,

129.2, 129.8 (C_arom.), 133.9, 137.0, 137.9 (i-C), 163.5, 164.5 (NCO)

N,NЈ-Bis[5-(diethylamino)-1,3-phenyl-2,4-diaza-6-oxa-1,3,5-hexatri-

enyl]piperazine (5a): From 2-(diethylamino)-4,6-diphenyl-1,3,5-oxa-

Eur. J. Org. Chem. 2008, 5740–5754

www.eurjoc.org

5749

J.-B. Greving, H. Behrens, R. Fröhlich, E.-U. Würthwein

FULL PAPER

ppm. IR (KBr): ν = 3058 (m, CH_arom.), 3028 (m, CH_arom.), 2974

triethylamine (1.4 mL, 10 mmol) and N,NЈ-diphenyl-p-xylylenedi-

˜

(m, CH_aliph.), 2929 (m, CH_aliph.), 2869 (m, CH_aliph.), 1633 (vs, amine (5.26 g, 10 mmol). The crude product was purified by column

C=O), 1606 (vs, C=N), 1591 (vs, C=N), 1571 (vs, C=N), 1498 (m, chromatography with petroleum ether/tert-butyl methyl ether (3:1)

C=C), 1469 (s), 1417 (s), 1375 (s), 1321 (s), 1271 (s), 1255 (s), 1224 as eluent. Yield: 0.83 g (0.6 mmol, 12%), yellow solid, m.p. 199 °C.

1

(m), 1155 (m), 1064 (s), 1020 (m), 993 (m), 943 (m), 927 (w), 893

R_f= 0.12 (petroleum ether/tert-butyl methyl ether, 3:1). H NMR

(m), 856 (w), 808 (m), 792 (m), 775 (m), 732 (m), 696 (m) cm^–1. (300.13 MHz, CDCl₃): δ = 4.31–4.77 (br., 8 H, CH₂), 7.02–7.12 (m,

MS (ESI): m/z (%) = 825 [M + Na]⁺, 803 [M + H]⁺. C₅₀H₅₈N₈O₂

(803.47): calcd. C 74.78, H 7.28, N 13.95; found C 74.54, H 7.20,

N 13.95.

12 H, CH_arom.), 7.35–7.48 (m, 18 H, CH_arom.), 7.69–7.78 (m, 8 H,

CH_arom.) ppm. ¹³C NMR (75.47 MHz, CDCl₃): δ = 50.2, 50.6, 52.1

(CH₂), 125.1, 126.2, 126.9 (i-C_arom.), 127.0, 129.0, 129.4, 130.3,

130.5, 131.2, 131.4 (CH_arom.), 134.2, 136.0, 136.2 (i-C_arom.), 160.9,

N,NЈ-Diethyl-N,NЈ-bis[1,3,5-tris(4-bromophenyl)-6-oxa-2,4-diaza-

1,3,5-hexatrienyl]-p-xylylenediamine (5d): From 2b (0.98 g,

5.0 mmol), triethylamine (1.4 mL, 10.0 mmol) and N,NЈ-diethyl-p-

xylylenediamine (5.26 g, 10.0 mmol). The crude product was puri-

fied by column chromatography with petroleum ether/tert-butyl

methyl ether (1:1) as eluent. Yield: 0.67 g (0.5 mmol, 10%), yellow

solid, m.p. 178 °C. R_f= 0.13 (petroleum ether ether/tert-butyl

162.0 (CN), 174.1 (CO) ppm. IR (KBr): ν = 3085 (w, CH_arom.),

˜

3062 (w, CH_arom.), 3031 (w, CH_arom.), 2923 (w, CH_aliph.), 2854 (w,

CH_aliph.), 1662 (s, C=O), 1635 (s, C=N), 1558 (s, C=C), 1494 (m),

1452 (m), 1251 (m), 1163 (m), 1068 (m), 1008 (m), 906 (m), 831

( m ) , 7 3 0 ( w ) c m ^{– 1}. M S ( E S I ) : m / z = 1 4 1 1 [ M + H ] ⁺

.

C₆₄H₅₂Br₆N₆O₂(1416.57): calcd. C 54.26, H 3.70, N 5.93; found C

54.48, H 3.18, N 5.76.

1

methyl ether, 1:1). H NMR (300.13 MHz, CDCl₃): δ = 1.05–1.29

X-ray Crystal Structure Analysis of 5f:^[13]Formula C₆₄H₄₆Br₆N₆O₂,

M = 1410.53, colourless crystal 0.15 ϫ 0.07 ϫ 0.03 mm, a =

18.402(1), b = 9.055(1), c = 18.417(1) Å, β = 102.07(1)°, V =

3001.0(4) Å³, ρ_calcd.= 1.561 gcm^–3, µ = 4.062 mm^–1, empirical ab-

sorption correction (0.581ՅTՅ0.888), Z = 2, monoclinic, space

group P2/c (No. 13), λ = 0.71073 Å, T = 198 K, ω and φ scans,

7497 reflections collected (Ϯh, Ϯk, Ϯl), [(sinθ)/λ] = 0.59 Å^–1, 4792

independent (R_int= 0.058) and 2317 observed reflections

[IՆ2σ(I)], 352 refined parameters, R = 0.073, wR²= 0.212, max./

min. residual electron density 0.75/–0.67 eÅ^–3, weakly diffracting

crystal leading to reduced quality of the analysis, hydrogen atoms

calculated and refined as riding atoms.

(br., 6 H, NCH₂CH₃), 3.13–3.59 (br., 4 H, CH₂), 4.37–4.79 (br., 4

H, CH₂), 6.97–7.17 (m, 8 H, CH_arom.), 7.43–7.70 (m, 18 H,

CH_arom.), 7.93 (m, 2 H, CH_arom.) ppm. ¹³C NMR (75.47 MHz,

CDCl₃): δ = 13.8 (br., CH₃), 43.5, 51.2 (CH₂), 124.8, 126.02, 126.8

(i-C_arom.), 128.7, 129.3, 130.3, 130.5, 131.1, 131.3, 131.7 (CH_arom.),

136.0 (i-C_arom.), 160.9, 162.0 (CN), 178.0 (CO) ppm. IR (KBr): ν

˜

= 3083 (w, CH_arom.), 3060 (w, CH_arom.), 3031 (w, CH_arom.), 2962

(w, CH_aliph.), 2931 (w, CH_aliph.), 2871 (w), 1662 (s, C=O), 1635 (s,

C=N), 1558 (s, C=C), 1496 (m), 1461 (m), 1394 (m), 1280 (m), 1166

(m), 1087 (m), 1068 (m), 1031 (m), 906 (m), 825 (m), 730 (m) cm^–1.

MS (ESI): m/z = 1286 [M + H]⁺. C₅₄H₄₈Br₆N₆O₂(1292.43): calcd.

C 50.18, H 3.74, N 6.50; found C 50.61, H 3.24, N 6.32.

X-ray Crystal Structure Analysis of 5d:^[13]Formula C₅₄H₄₂Br₆N₆O₂,

M = 1286.40, colourless crystal 0.15 ϫ 0.10 ϫ 0.05 mm, a =

16.551(1), b = 7.818(1), c = 20.084(1) Å, β = 105.87(1)°, V =

2499.7(4) Å³, ρ_calcd.= 1.709 gcm^–3, µ = 4.867 mm^–1, empirical ab-

sorption correction (0.529ՅTՅ0.793), Z = 2, monoclinic, space

group P2₁/n (No. 14), λ = 0.71073 Å, T = 198 K, ω and φ scans,

20494 reflections collected (Ϯh, Ϯk, Ϯl), [(sinθ)/λ] = 0.66 Å^–1, 5928

independent (R_int= 0.062) and 3790 observed reflections [I ³2σ(I)],

308 refined parameters, R = 0.048, wR²= 0.109, max./min. residual

electron density 0.87/–0.73 eÅ^–3, hydrogen atoms calculated and

refined as riding atoms.

2,6-Bis{[5-(diethylamino)-1,3-diphenyl-2,4-diaza-6-oxa-1,3,5-

hexatrienyl]amino}pyridine (6): From a solution of 2-(dieth-

ylamino)-4,6-diphenyl-1,3,5-oxadiazinium pentachlorostannate

(2a)^[1](3.61 g, 6.0 mmol) in dry dichloromethane (40 mL) and 2,6-

diaminopyridine (0.65 g, 3.0 mmol). The resultant precipitate was

purified by recrystallisation from hot acetone. Yield: 1.51 g

(2.1 mmol, 70 %), light yellow solid, m.p. 165 °C. ¹H NMR

(300.13 MHz, CDCl₃): δ = 0.74 (t, ³J = 7.1 Hz, 3 H, CH₂CH₃),

3

1.06 (m, 6 H, CH₂CH₃), 1.25 (t, J = 7.1 Hz, 3 H, CH₂CH₃), 2.98

3

(m, 4 H, NCH₂), 3.47 (q, J = 7.0 Hz, 2 H, NCH₂), 3.47 (q, J =

3

7.0 Hz, 2 H, NCH₂), 3.58 (q, J = 7.1 Hz, 2 H, NCH₂), 7.02–7.15

(m, 6 H, CH_arom.), 7.25–7.35 (m, 9 H, CH_arom.), 7.44–7.46 (m, 2 H,

N,NЈ-Bis[5-(diethylamino)-1,3-phenyl-2,4-diaza-6-oxa-1,3,5-hexatri-

enyl]-N,NЈ-diphenyl-p-xylylenediamine (5e): From a solution of 2-

(diethylamino)-4,6-diphenyl-1,3,5-oxadiazinium pentachlorostann-

ate (2a)^[1](3.61 g, 6.0 mmol) in dry dichloromethane, 0.6 mL

(6.0 mmol) triethylamine and N,NЈ-diphenyl-p-xylylenediamine

(0.95 g, 3.0 mmol). The crude product was purified by column

chromatography (cyclohexane/ethyl acetate, 5:1 + 5% of triethyl-

amine), and the resultant precipitate was purified by recrystalli-

sation from hot acetone. Yield: 0.27 g (0.3 mmol, 9%), colourless

solid, m.p. 198 °C. R_f= 0.053 (cyclohexane/ethyl acetate, 5:1 + 5%

of triethylamine).¹H NMR (400.13 MHz, CDCl₃): δ = 1.04 (t, ³J =

CH_arom.), 7.76–7.89 (m, 5 H, CH_arom.), 8.32–8.35 (m, 1 H, CH_arom.

)

ppm. ¹³C NMR (75.47 MHz, CDCl₃): δ = 13.0, 13.4, 13.8, 14.6

(CH₃), 39.9, 40.3, 41.7, 42.1 (br., CH₂), 110.8 (CN), 117.5, 127.5,

127.7, 127.8, 128.0, 128.2, 128.3, 128.7, 128.8, 129.8, 130.4, 130.4

(C_arom.), 134.8, 136.4 139.9 (i-C_arom.), 149.9, 154.8, 157.6, 161.8

(CN), 163.5 (CO) ppm. IR (KBr): ν = 3298 (s, NH), 3060 (m,

˜

CH_arom.), 2976 (m, CH_aliph.), 2931 (m, CH_aliph.), 2858 (m, CH_aliph.),

1654 (vs, C=O), 1604 (vs, C=N), 1548 (vs, C=N), 1502 (m, C=C),

1490 (s, C=C), 1448 (s), 1417 (s), 1377 (s), 1326 (s), 1271 (vs), 1224

(m), 1190 (m), 1157 (s), 1101 (m), 1072 (m), 1026 (m), 927 (m), 900

(m), 877 (m), 755 (m), 695 (m) cm^–1. MS (ESI): m/z = 782, 742 [M

+ Na]⁺, 720 [M + H]⁺, 391. C₄₃H₄₅N₉O₂(719.37): calcd. C 71.74,

H 6.30, N 17.51; found C 71.60, H 6.20, N 17.45.

3

9.2 Hz, 6 H, CH₃), 1.22 (t, ³J = 9.2 Hz, 6 H, CH₃), 3.17 (q, J =

9.2 Hz, 4 H, NCH₂), 3.46 (q, ³J = 9.2 Hz, 4 H, NCH₂), 4.32 (s,

4 H, Aryl-CH₂), 4.77 (s, 4 H, Aryl-CH₂), 7.15–7.38 (m, 34 H,

CH_arom.) ppm. ¹³C NMR (100.61 MHz, CDCl₃): δ = 13.9, 14.4

(CH₃) 40.6, 42.3 (NCH₂), 52.9 (Aryl-CH₂), 127.9, 128.5, 129.1,

129.8, 130.3 (C_arom.), 133.9, 137.9 (i-C_arom.), 161.3, 163.6 (CN),

164.7 (CO) ppm. MS (ESI): m/z = 949 [M + Na]⁺, 927 [M + H]⁺,

622, 475 [M + 2 Na]⁺. C₆₀H₆₂N₈O₂(927.20): calcd. C 77.72, H

6.74, N 12.09; found C 77.93, H 6.38, N 12.08.

Tris(2-{[5-(diethylamino)-1,3-diphenyl-2,4-diaza-6-oxa-1,3,5-

hexatrienyl]amino}ethyl)amine (7a): From 2-(diethylamino)-4,6-di-

phenyl-1,3,5-oxadiazinium pentachlorostannate (2a)^[1](7.22 g,

12.0 mmol) in dry dichloromethane (30 mL) and tris(2-aminoethyl)

amine (0.58 g, 4.0 mmol). The crude solid product was purified by

recrystallisation from acetone. Yield: 2.68 g (2.5 mmol, 63 %),

1

N,NЈ-Dibenzyl-N,NЈ-bis[1,3,5-tris(4-bromophenyl)-6-oxa-2,4-diaza- colourless solid, m.p. 176 °C. H NMR (300.13 MHz, CDCl₃): δ =

1,3,5-hexatrienyl]-p-xylylenediamine (5f): From 2b (0.81 g, 5 mmol),

0.74 (t, ³J = 6.9 Hz, 9 H, CH₃), 0.84 (t, ³J = 6.9 Hz, 9 H, CH₃),

5750

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Eur. J. Org. Chem. 2008, 5740–5754

Multivalent 1-Oxa-3,5,7-triazahepta-1,3,5-trienes

2.80–2.90 (br., 18 H, NCH₂), 3.53 [s, 6 H, NCH_2(tren)] 7.01–7.44 (m, (w, CH_arom.), 3026 (w, CH_arom.), 2958 (m, CH_aliph.), 2918 (m,

24 H, CH_arom.), 7.81–7.83 (d, ³J = 6.7 Hz, 6 H, p-CH_arom.) ppm.

CH_aliph.), 2895 (m, CH_aliph.), 2852 (s, CH_aliph.), 1612 (vs, C=O),

1598 (vs, C=N), 1573 (vs, C=N), 1523 (vs, C=C), 1454 (vs), 1431

¹³C NMR (75.47 MHz, CDCl₃): δ = 12.3, 12.9 (CH₃), 38.8, 39.6,

40.8 (NCH₂), 52.09 [NCH_2(tren)], 126.8, 127.2, 127.4 (C_arom.), 129.0, (vs), 1404 (vs), 1359 (s), 1299 (s), 1284 (s), 1245 (vs), 1170 (s), 1112

129.3 (p-C_arom.), 134.3, 136.9 (i-C_arom.), 157.6, 162.0 (CN), 162.9 (vs), 1068 (m), 1020 (m), 999 (s), 966 (m), 927 (w), 893 (w), 848

(CO) ppm. IR (KBr): ν = 3286 (s, NH), 3078 (m, CH_arom.), 3060 (m), 802 (m), 773 (m), 756 (m), 696 (m) cm^–1. MS (ESI): m/z =

˜

(m, CH_arom.), 3028 (m, CH_arom.), 2974 (m, CH_aliph.), 2931 (m, CH_al-

1153 [M + Na]⁺, 1031 [M + H]⁺, 102 [NEt₃+ H]⁺, 76 [Ph]⁺.

_iph.), 2871 (m, CH_aliph.), 2792 (m, CH_aliph.), 1608 (vs, C=O), 1570 C₅₇H₇₈N₁₆O₉(1130.61): calcd. C 60.51, H 6.95, N 19.81; found C

(s, C=N), 1537 (vs, C=C), 1488 (m, C=C), 1463 (s), 1446 (s), 1417 60.01, H 7.03, N 19.63.

(s), 1373 (s), 1315 (m), 1274 (s), 1155 (m), 1116 (m), 1064 (m), 1026

1,3,5-Tris[3,5-bis(diisopropylamino)-1-(propylamino)-6-oxa-2,4-di-

(w), 954 (vw), 929 (w), 900 (w), 877 (w), 808 (w), 773 (m), 711 (m),

aza-1,3,5-hexatrienyl]benzene (8): From 2,2Ј,2ЈЈ-(1,3,5-phenylene)-

694 (m), 659 (m) cm^–1. MS (ESI): m/z = 1084.6 [M + Na]⁺, 1062

tris[4,6-bis(diisopropylamino)-1-oxa-3,5-diazinium] tris(pentachlo-

[M + H]⁺, 542 [M + H + Na]²⁺, 531 [M + 2 H]²⁺, 495, 220.

rostannate) (1d)^[11](14.87 g, 8.3 mmol) and n-propylamine (4.0 mL,

C₆₃H₇₅N₁₃O₃(1061.61): calcd. C 71.23, H 7.12, N 17.14; found C

50.0 mmol). The crude product was purified by column chromatog-

70.84, H 6.92, N 17.11.

raphy with pentane/tert-butyl methyl ether (3:1) with 1% triethyl-

amine as eluent. Yield: 4.00 g (3.1 mmol, 37%), light yellow solid,

Tris(2-{[3,5-bis(diethylamino)-1-phenyl-2,4-diaza-6-oxa-1,3,5-

hexatrienyl]amino}ethyl)amine (7b): From 2,4-bis(diethylamino)-6-

phenyl-1-oxa-3,5-diazinium pentachlorostannate (2c)^[14](7.15 g,

12.0 mmol) in dry dichloromethane (30 mL) and tris(2-aminoethyl)-

amine (0.58 g, 4.0 mmol). The crude product was purified by col-

umn chromatography with n-pentane/acetone (5:1) with 10% tri-

ethylamine as eluent. Yield: 0.81 g (0.7 mmol, 18%), colourless so-

lid, m.p. 182 °C. R_f= 0.55 (n-pentane/acetone, 5:1 with 10% trieth-

ylamine). ¹H NMR (300.13 MHz, CDCl₃): δ = 0.51 (s, 18 H, CH₃),

1.12 (s, 18 H, CH₃), 2.17–2.59 (br., 18 H, NCH₂), 3.44 (s, 12 H,

NCH₂), 3.73 [s, 6 H, NCH_2(tren)], 7.26–7.40 (br., 12 H, CH_arom.),

7.58–7.60 (br., 3 H, p-CH_arom.) ppm. ¹³C NMR (75.47 MHz,

CDCl₃): δ = 13.9 (CH₃), 27.8, 39.6 (NCH₂), 41.9 (NCH₂), 52.8

[NCH_2(tren)], 127.6, 127.7 (C_arom.), 129.0 (p-C_arom.) 136.7 (i-C_arom.),

m.p. 92 °C. R_f= 0.18 (pentane/tert-butyl methyl ether, 3:1 with 1%

1

triethylamine). H NMR (300.13 MHz, CDCl₃): δ = 0.92–0.97 (m,

9 H, NCH₂CH₂CH₃), 1.02–1.27 (br., 72 H, NCHCH₃), 1.58–1.70

(m, 6 H, NCH₂CH₂CH₃), 3.15–3.45 (br., 12 H, NCH), 3.72 (br.,

6 H, NCH₂CH₂CH₃), 4.31 (br., 3 H, NH), 6.69–8.64 (br., 3 H,

CH_arom.) ppm. ¹³C NMR (75.47 MHz, CDCl₃): δ = 11.6, 21.0, 21.3,

22.2 (CH₃), 44.1, 46.8, 50.9 (NCH, CH₂), 129.5, 133.7 (CH_arom.),

155.2, 156.4 (CN), 162.8 (CO) ppm. IR (KBr): ν = 3301 (w, NH),

˜

3064 (w, CH_arom.), 2966 (s, CH_aliph.), 2931 (s, CH_aliph.), 2873 (m,

CH_aliph.), 1631 (s, C=O), 1579 (s, C=N), 1552 (s, C=C), 1442 (s),

1423 (s), 1365 (s), 1328 (s), 1220 (m), 1151 (m), 1132 (m), 1066 (w),

1041 (w) cm^–1. MS (ESI): m/z = 1091 [M + H]⁺, 545 [(M + 2 H)/

2]⁺, daughters of 1091: 1032 [(M + H) – NHPr]⁺, 990 [(M + H) –

NiPr₂]⁺, 931 [(M + H) – 2 NHPr]⁺, 889 [(M + H) – NHPr –

NiPr₂]⁺, 787 [(M + H) – 3 NHPr]⁺. C₆₀H₁₁₁N₁₅O₃(1090.64): calcd.

C 66.08, H 10.26, N 19.26; found C 65.69, H 10.37, N 19.08.

160.3, 160.5 (CN), 161.8 (CO) ppm. IR (KBr): ν = 3263 (s, NH),

˜

3082 (m, CH_arom.), 3026 (m, CH_arom.), 2974 (s, CH_aliph.), 2927 (s,

CH_aliph.), 2868 (m, CH_aliph.), 2777 (m, CH_aliph.), 2723 (m, CH_aliph.),

1604 (vs, C=O), 1583 (s, C=N), 1523 (vs, C=C), 1467 (vs, C=C),

1406 (vs), 1363 (s), 1357 (s), 1344 (s), 1319 (s), 1282 (vs), 1234 (s),

1166 (s), 1141 (m), 1089 (s), 1060 (s), 947 (w), 920 (w), 896 (w),

833 (vw), 812 (m), 769 (m), 754 (m), 692 (m) cm^–1. MS (ESI): m/z

= 1047 [M + H]⁺, 659. C₅₇H₉₀N₁₆O₃(1046.73): calcd. C 65.36, H

8.66, N 21.40; found C 65.39, H 8.59, N 20.95.

Metal Complexes of the Ligands 3–7. General Procedure: The ligand

(0.05 mmol) and the metal salt (0.10 mmol) were co-dissolved in

DMF or ethanol (2 mL). After centrifugation, diethyl ether was

allowed to diffuse into the solution. Overnight coloured crystals

were formed. After one week, these were collected, washed with

diethyl ether, and dried under reduced pressure.

X-ray Crystal Structure Analysis of 7b:^[13]Formula C₅₇H₉₀N₁₆O₃,

M = 1047.45, colourless crystal 0.50 ϫ 0.320 ϫ 0.15 mm, a =

11.978(1), b = 26.591(1), c = 19.989(1) Å, β = 107.15(1)°, V =

6083.5(6) Å³, ρ_calcd.= 1.144 gcm^–3, µ = 0.583 mm^–1, empirical ab-

sorption correction (0.759ՅTՅ0.918), Z = 4, monoclinic, space

group P2₁/n (No. 14), λ = 1.54178 Å, T = 223 K, ω and φ scans,

{1,4-Bis[3,5-bis(diisopropylamino)-1-(propylamino)-6-oxa-2,4-diaza-

1,3,5-hexatrienyl]benzene}bis[zinc(II) dibromide] (3a·ZnBr₂): From

3a (38 mg, 0.05 mmol) and zinc(II) bromide (22 mg, 0.10 mmol) in

DMF (2 mL). Yield: 32 mg (0.03 mmol, 53%), colourless crystals,

m.p. 217 °C. IR (KBr): ν = 3251 (m, NH), 3051 (s, CH_arom.), 2969

˜

(s, CH_aliph.), 2941 (s, CH_aliph.), 2873 (s, CH_aliph.), 1616 (vs, C=O/

C=N), 1566 (vs, C=C), 1521 (vs), 1459 (s), 1431 (s), 1366 (s), 1331

(s), 1215 (m), 1166 (m), 1118 (m), 1069 (m), 969 (w), 894 (w), 863

(w), 844 (w), 792 (w), 758 (m), 723 (w), 633 (w), 573 (w), 555 (w)

cm^–1. MS (MALDI, matrix DCTB): m/z (%) = 978 (25) [M –

ZnBr₂]⁺, 896 (20) [M – ZnBr₃]⁺, 753 (35) [M – 2 ZnBr₂]⁺, 652 (100)

38310 reflections collected (Ϯh, Ϯk, Ϯl), [(sinθ)/λ] = 0.59 Å^–1

,

10071 independent (R_int= 0.047) and 6681 observed reflections

[IՆ2σ(I)], 706 refined parameters, R = 0.045, wR²= 0.126, max./

min. residual electron density 0.26/–0.20 eÅ^–3, hydrogen atoms at

N4 from difference Fourier calculations, others calculated and all

refined as riding atoms.

[M – 2 ZnBr₂– NiPr₂]⁺. UV/Vis (acetonitrile): λ_max(ν, ε) = 249

˜

(40160, 40933) 202 (49504 cm^{– 1}, 61000 ^{– 1}cm^{– 1}) n m.

C₄₂H₇₆Br₄N₁₀O₂Zn₂(1203.50): calcd. C 41.92, H 6.37, N 11.64;

found C 41.22, H 6.19, N 11.34.

Tris{2-[(3,5-dimorpholino-1-phenyl-2,4-diaza-6-oxa-1,3,5-hexatri-

enyl)amino]ethyl}amine (7c): From 2,4-dimorpholino-6-diphenyl-1-

oxa-3,5-diazinium pentachlorostannate (2d)^[14](7.49 g, 12.0 mmol)

and tris(2-aminoethyl)amine (0.58 g, 4.0 mmol). The crude product

was purified by recrystallisation from acetone. Yield: 1.93 g

(1.7 mmol, 43 %), colourless solid, m.p. 165 °C. ¹H NMR

X-ray Crystal Structure Analysis of 3a·ZnBr₂:^[13]Formula

C₄₂H₇₆Br₄N₁₀O₂Zn₂, M = 1203.51, light yellow crystal 0.10 ϫ 0.05

ϫ0.03 mm, a = 10.073(1), b = 10.748(1), c = 13.410(1) Å, α =

(300.13 MHz, CDCl₃): δ = 1.95 (br., 11 H, NCH₂), 3.00 (br., 15 H 75.43(1), β = 73.18(1), γ = 78.93(1)°, V = 1333.8(2) Å³, ρ_calcd.

=

NCH₂), 3.69 (br., 34 H, NCH₂, OCH₂), 7.37–7.46 (m, 15 H, 1.498 g cm^–3, µ = 3.937 mm^–1, empirical absorption correction

CH_arom.), 8.26 (s, 3 H, NH) ppm. ¹³C NMR (75.47 MHz, CDCl₃): (0.694ՅTՅ0.891), Z = 1, triclinic, space group P1 (No. 2), λ =

¯

δ = 38.6, 44.6 [NCH_2(mor.)], 52.4 [NCH_2(tren)], 66.3, 66.8 [OCH_2(mor.)], 0.71073 Å, T = 198 K, ω and φ scans, 14284 reflections collected

127.6, 129.7 (C_arom.), 136.7 (i-C_arom.), 161.5, 161.6 (CN), 161.8

(CO) ppm. IR (KBr): ν = 3286 (m, NH), 3101 (w, CH_arom.), 3060

(Ϯh, Ϯk, Ϯl), [(sinθ)/λ] = 0.66 Å^–1, 6298 independent (R_int= 0.045)

and 4335 observed reflections [IՆ2σ(I)], 284 refined parameters,

˜

Eur. J. Org. Chem. 2008, 5740–5754

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5751

J.-B. Greving, H. Behrens, R. Fröhlich, E.-U. Würthwein

FULL PAPER

R = 0.044, wR²= 0.087, max./min. residual electron density

0.60/–0.63 eÅ^–3, hydrogen atom at N61 from difference Fourier cal-

culations, others calculated and all refined as riding atoms.

in DMF (2.0 mL). Yield: 34 mg (0.04 mmol, 87%), green crystals,

m.p. 161 °C. IR (KBr): ν = 3273 (m, NH), 3197 (m, NH), 2954 (s,

˜

CH_aliph.), 2933 (s, CH_aliph.), 2873 (s, CH_aliph.), 1604 (vs, C=O/C=N),

1564 (vs, C=C), 1467 (s), 1407 (s), 1390 (s), 1292 (m), 1278 (m),

1263 (m), 1199 (m), 1157 (w), 1143 (w), 1093 (w), 1047 (w), 983

(w), 875 (w), 854 (w), 756 (w), 715 (w), 682 (w), 592 (w) cm^–1. MS

(MALDI, matrix DCTB): m/z (%) = 645 (20) [M – CuCl₂]⁺,

607 (15) [M – CuCl₃]⁺, 571 (55) [M – CuCl₄]⁺, 509 (50) [M –

2 CuCl₂]⁺, 464 (90) [M – 2 CuCl₂– NMe₂]⁺, 419 (100) [M –

{1,4-Bis[3,5-bis(diisopropylamino)-1-(propylamino)-6-oxa-2,4-diaza-

1,3,5-hexatrienyl]benzene}bis[cobalt(II) dichloride] (3a·CoCl₂):

From 3a (38 mg, 0.05 mmol) and cobalt(II) chloride hexahydrate

(23 mg, 0.10 mmol) in DMF (2 mL). Yield: 30 mg (0.03 mmol,

60%), dark blue crystals, m.p. 251 °C. IR (KBr): ν = 3255 (m, NH),

˜

3058 (s, CH_arom.), 2970 (s, CH_aliph.), 2935 (s, CH_aliph.), 2875 (s,

CH_aliph.), 1608 (vs, C=O/C=N), 1558 (vs, C=C), 1523 (vs), 1456

(s), 1423 (s), 1367 (s), 1336 (s), 1215 (m), 1149 (m), 1136 (m), 1068

(m), 1041 (m), 964 (w), 889 (w), 867 (w), 840 (w), 796 (w), 754 (m),

711 (w), 624 (w), 578 (w), 547 (w) cm^–1. MS (MALDI, matrix

DCTB): m/z (%) = 974 (10) [M – Cl]⁺, 939 (5) [M – 2 Cl]⁺, 881

(40) [M – CoCl₂]⁺, 846 (100) [M – CoCl₃]⁺, 810 (10) [M –

2 CuCl₂– 2 NMe₂]⁺. UV/Vis (acetonitrile): λ_max(ν, ε) = 465 (21505,

˜

101), 252 (39682, 7617), 216 (46296, 7904), 202 (49504 cm^–1

,

8489 ^–1cm^–1) nm. C₂₄H₄₈Cl₄Cu₂N₁₀O₂(777.61): calcd. C 37.07,

H 6.22, N 18.01; found C 36.90, H 6.08, N 17.62.

X-ray Crystal Structure Analysis of 3b·CuCl₂:^[13]Formula

C₂₄H₄₈Cl₄Cu₂N₁₀O₂·2C₃H₇NO, M = 923.80, green crystal

0.10ϫ0.05ϫ0.03 mm, a = 7.591(1), b = 10.987(1), c = 13.858(1) Å,

α = 108.91(1), β = 96.37(1), γ = 90.12(1)°, V = 1085.8(2) Å³, ρ_calcd.

= 1.413 gcm^–3, µ = 1.273 mm^–1, empirical absorption correction

CoCl₄]⁺, 753 (65) [M – 2 CoCl₂]⁺, 652 (100) [M – 2 CoCl₂

–

NiPr₂]⁺. UV/Vis (acetonitrile): λ_max(ν, ε) = 685 (14598, 231), 587

˜

(17035, 180), 233 (42918 cm^–1, 17828 ^–1cm^–1) nm. C₄₂H₇₆Cl₄-

Co₂N₁₀O₂(1012.80): calcd. C 49.81, H 7.56, N 13.83; found C

48.76, H 7.47, N 13.52.

¯

(0.883ՅTՅ0.963), Z = 1, triclinic, space group P1 (No. 2), λ =

0.71073 Å, T = 198 K, ω and φ scans, 6094 reflections collected

(Ϯh, Ϯk, Ϯl), [(sinθ)/λ] = 0.59 Å^–1, 3786 independent (R_int= 0.057)

and 2534 observed reflections [IՆ2σ(I)], 245 refined parameters,

R = 0.066, wR²= 0.164, max./min. residual electron density 1.41/–

0.62 eÅ^–3, hydrogen atom at N61 from difference Fourier calcula-

tions, others calculated and all refined as riding atoms.

X-ray Crystal Structure Analysis of 3a·CoCl₂:^[13]Formula

C₄₂H₇₆Cl₄Co₂N₁₀O₂, M = 1012.79, blue crystal 0.40 ϫ 0.25 ϫ

0.10 mm, a = 9.972(1), b = 10.746(1), c = 13.226(1) Å, α = 75.09(1),

β = 73.20(1), γ = 78.82(1)°, V = 1300.1(2) Å³, ρ_calcd.= 1.294 gcm^–3,

µ = 0.886 mm^–1, empirical absorption correction (0.718 Յ T Յ

¯

0.917), Z = 1, triclinic, space group P1 (No. 2), λ = 0.71073 Å, T

Bis(acetonitrile)bis{N,NЈ-bis[5-(diethylamino)-1,3-diphenyl-2,4-di-

aza-6-oxa-1,3,5-hexatrienyl]-1,3-propylenediamine}dinickel(II)

Bis(perchlorate) [4b·Ni(ClO₄)₂]: A solution of 4b (68 mg, 0.1 mmol)

in acetonitrile (1.9 mL) was treated with nickel(II) perchlorate

(36 mg, 0.1 mmol). After removal of undissolved starting material

by filtration, diethyl ether (10 mL) was carefully added to the fil-

trate to form an upper layer. After 3 d, blue crystals were formed.

Yield: 50 mg (0.04 mol, 80%), blue crystals, m.p. 195 °C. ¹H NMR

(300.13 MHz, CDCl₃): δ = 0.85 (br.), 0.99 (br.), 2.07 (br.), 2.73 (br.)

3.14 (br.), 3.55 (br.), 7.32 (br.), 7.81 (br.), 8.03 (br.) ppm. ¹³C NMR

(75.47 MHz, CDCl₃): δ = 12.4, 12.6 (CH₃), 25.5 (CH₂), 38.7 (br.,

NCH₂), 126.4, 126.7, 126.8, 128.9, 129.1 (CH_arom.), 133.5, 136.2 (i-

= 198 K, ω and φ scans, 12324 reflections collected (Ϯh, Ϯk, Ϯl),

[(sinθ)/λ] = 0.66 Å^–1, 6162 independent (R_int= 0.035) and 5154 ob-

served reflections [IՆ2σ(I)], 283 refined parameters, R = 0.035,

wR²= 0.085, max./min. residual electron density 0.39/–0.39 eÅ^–3,

hydrogen atom at N61 from difference Fourier calculations, others

calculated and all refined as riding atoms.

{1,4-Bis[3,5-bis(dimethylamino)-1-(propylamino)-6-oxa-2,4-diaza-

1,3,5-hexatrienyl]butane}bis[zinc(II) dibromide] (3b·ZnBr₂): From 3b

(26 mg, 0.05 mmol) and zinc(II) bromide (22 mg, 0.10 mmol) in

DMF (2 mL). Yield: 28 mg (0.03 mmol, 58%), colourless crystals,

m.p. 190 °C. IR (KBr): ν = 3303 (s, NH), 2966 (s, CH_aliph.), 2935

˜

CH_arom.), 157.5, 160.7 (CN), 161.8 (CO) ppm. IR (KBr): ν = 3384

˜

(s, CH_aliph.), 2875 (s, CH_aliph.), 1610 (vs, C=O/C=N), 1558 (vs,

C=C), 1490 (s), 1411 (s), 1384 (s), 1286 (m), 1205 (m), 1141 (m),

1091 (w), 1043 (w), 972 (w), 896 (w), 846 (w), 827 (w), 756 (w), 707

(w), 676 (w) cm^–1. MS (MALDI, matrix DCTB): m/z (%) = 814

(10) [M – ZnBr]⁺, 734 (25) [M – ZnBr₂]⁺, 653 (30) [M – ZnBr₃]⁺,

509 (50) [M – 2 ZnBr₂]⁺, 464 (80) [M – 2 ZnBr₂– NMe₂]⁺, 419

(br., NH), 3075 (w, CH_arom.), 2932 (w, CH_aliph.), 1653 (m, C=O),

1623 (s, C=N), 1583 (s, C=N), 1473 (m, C=C), 1457 (m), 1436 (m),

1419 (m), 1298 (m), 1145 (vs), 1116 (vs), 1090 (vs), 700 (m), 637

(s), 629 (s) cm^–1. MS (ESI): m/z = 1630, 1528, 1185, 1134, 1013,

841, 685.5 [C H N O ], 371. UV/Vis (acetonitrile): λ (ν, ε) = 306

˜

41 48

8

2

(sh, 32679, 5472), 243 (41152 cm^–1, 15935 ^–1cm^–1) nm.

C₈₆H₁₀₈Cl₄N₁₈Ni₂O₂₂·2CH₃CN (2080.57): calcd. C 51.84, H 5.41,

N 13.43; found C 51.85, H 5.53, N 13.44.

(100) [M – 2 ZnBr₂– 2 NMe₂]⁺. UV/Vis (acetonitrile): λ_max(ν, ε)

˜

= 255 (39215, 26930), 217 (46082 cm^–1, sh, 24872 ^–1cm^–1) nm.

C₂₄H₄₈Br₄N₁₀O₂Zn₂(959.08): calcd. C 30.06, H 5.04, N 14.60;

found C 30.55, H 4.82, N 14.65.

X-ray Crystal Structure Analysis of 4b·Ni(ClO₄)₂:^[13]Formula

C₄₁H₄₆NiN₁₈O₂·2CH₃CN·H₂O·2ClO₄·2C₄H₁₀O, M = 1188.83,

blue crystal 0.30ϫ0.30ϫ0.20 mm, a = 12.620(1), b = 14.737(1),

c = 17.209(1) Å, α = 95.72(1), β = 101.72(1), γ = 91.89(1)°, V =

3113.6(4) Å³, ρ_calcd.= 1.268 gcm^–3, µ = 0.463 mm^–1, empirical ab-

sorption correction (0.874 Յ T Յ 0.913), Z = 2, triclinic, space

X-ray Crystal Structure Analysis of 3b·ZnBr₂:^[13]Formula

C₂₄H₄₈Br₄N₁₀O₂Zn₂, M = 959.10, colourless crystal 0.25ϫ0.15ϫ

0.05 mm, a = 12.514(1), b = 10.913(1), c = 13.939(1) Å, β =

102.67(1)°, V = 1857.2(3) Å³, ρ_{ca lc d.}= 1.715 g cm^{– 3}, µ =

5.631 mm^–1, empirical absorption correction (0.333ՅTՅ0.766), Z

= 2, monoclinic, space group P2₁/n (No. 14), λ = 0.71073 Å, T =

198 K, ω and φ scans, 12892 reflections collected (Ϯh, Ϯk, Ϯl),

[(sinθ)/λ] = 0.62 Å^–1, 3770 independent (R_int= 0.056) and 2488 ob-

served reflections [IՆ2σ(I)], 198 refined parameters, R = 0.047,

wR²= 0.103, max./min. residual electron density 0.82/–0.59 eÅ^–3,

hydrogen atom at N61 from difference Fourier calculations, others

calculated and all refined as riding atoms.

¯

group P1 (No. 2), λ = 0.71073 Å, T = 198 K, ω and φ scans, 34657

reflections collected (Ϯh, Ϯk, Ϯl), [(sinθ)/λ] = 0.66 Å^–1, 14757 inde-

pendent (R_int= 0.063) and 9480 observed reflections [IՆ2σ(I)],

667 refined parameters, R = 0.082, wR²= 0.259, max./min. residual

electron density 1.71/–0.72 eÅ^–3, ether and acetonitrile molecules

heavily disordered and refined with geometrical and thermal re-

straints, hydrogen atoms at O41 from difference Fourier calcula-

tions, others calculated and all refined as riding atoms.

{1,4-Bis[3,5-bis(dimethylamino)-1-(propylamino)-6-oxa-2,4-diaza-

1,3,5-hexatrienyl]butane}bis[copper(II) dichloride] (3b·CuCl₂): From

{N,NЈ-Bis[5-(diethylamino)-1,3-diphenyl-2,4-diaza-6-oxa-1,3,5-hexa-

3b (26 mg, 0.05 mmol) and copper(II) chloride (17 mg, 0.10 mmol) trienyl]-1,8-octylenediamine}nickel(II) Dinitrate [4d·Ni(NO₃)₂]: A

5752

www.eurjoc.org

Eur. J. Org. Chem. 2008, 5740–5754

Multivalent 1-Oxa-3,5,7-triazahepta-1,3,5-trienes

solution of 4d (34 mg, 0.05 mmol) in chloroform (1.9 mL) was

treated with nickel(II) nitrate (29 mg, 0.1 mmol). After removal of

undissolved starting material by filtration, diethyl ether (10 mL)

was carefully added to the filtrate to form an upper layer. After

3 d, green crystals were formed. Yield: 23 mg (0.03 mmol, 49%),

(2,6-Bis{[5-(diethylamino)-1,3-diphenyl-2,4-diaza-6-oxa-1,3,5-

hexatrienyl]amino}pyridine)(methanol)nickel(II) Dinitrate

[6·Ni(NO₃)₂]: 6 (36 mg, 0.05 mmol) and nickel(II) nitrate (29 mg,

0.1 mmol) were dissolved in methanol (1.9 mL). After centrifuga-

tion to remove any precipitate, diethyl ether was allowed to diffuse

into the solution. After 3 d, light pink crystals precipitated. Yield:

green crystals, m.p. 180–181 °C. IR (KBr): ν = 3425 (br., H O),

˜

2

3226 (br., NH), 3060 (m, CH_arom.), 2972 (s, CH_aliph.), 2935 (s, 38 mg (0.04 mmol, 82%), m.p. 211 °C. IR (KBr): ν = 3486 (m,

˜

CH_aliph.), 2869 (w, CH_aliph.), 1681 (s, C=O), 1624 (vs, C=O), 1612 NH), 3062 (w, CH_arom.), 2968 (m, CH_aliph.), 2927 (m, CH_aliph.),

(s, C=N) 1585 (vs, C=N), 1546 (vs, C=C), 1500 (vs, C=C), 1448 2871 (w, CH_aliph.), 2856 (w, CH_aliph.), 2360 (w), 2343 (w), 1577 (s,

(vs), 1431 (vs), 1382 (vs), 1301 (vs), 1276 (vs), 1217 (m), 1176 (w),

1139 (m), 1101 (m), 1076 (w), 1024 (m), 966 (vw), 833 (vw), 827

(vw), 817 (vw), 806 (w), 777 (w), 752 (vw), 725 (m), 698 (s), 669

(w), 624 (vw) cm^–1. MS (ESI): 874 [C₄₆H₅₈N₈NiO₂·NO₃]⁺, 811

C=O), 1566 (vs, C=N), 1467 (s, C=C), 1438 (m), 1417 (s), 1342

(m), 1282 (s), 1159 (w), 1099 (vs), 1078 (w), 1022 (w), 960 (vw),

914 (vw), 883 (vw), 777 (m), 698 (m) cm^–1. MS (ESI): m/z = 776

[C₄₃H₄₄N₉NiO₂]⁺. UV/Vis (acetonitrile): λ_max.(ν, ε) = 248

˜

[C₄₆H₅₇N₈Ni]⁺, 777 [C₄₆H₅₈N₈+ Na]⁺, 755 [C₄₆H₅₈N₈+ H]⁺, 442 (40322 cm^–1, 19100 ^–1cm^–1) nm. C₄₄H₄₉N₁₁NiO₉(934.65): calcd.

[C₄₆H₅₈N₈Ni·2H₂O]²⁺, 406 [C₄₆H₅₈N₈Ni]²⁺, 378 [C₄₆H₅₈N₈

+

,

C 57.22, H 5.03, N 17.07; found C 57.06, H 4.87, N 17.09.

2H]²⁺. UV/Vis (acetonitrile): λ_max.(ν, ε) = 241 (41493 cm^–1

˜

X-ray Crystal Structure Analysis of [6·Ni(NO₃)₂]:^[13]Formula

C₄₃H₄₅N₉NiO₂·CH₃OH·2NO₃, M = 934.65, colourless crystal

0.45 ϫ 0.20 ϫ 0.20 mm, a = 11.894(1), b = 13.522(1), c =

14.701(1) Å, α = 88.29(1), β = 80.43(1), γ = 80.34(1)°, V =

2298.4(3) Å³, ρ_calcd.= 1.351 gcm^–3, µ = 0.489 mm^–1, empirical ab-

sorption correction (0.810 Յ T Յ 0.909), Z = 2, triclinic, space

85100 ^–1cm^–1) nm. C₄₆H₅₈N₁₀NiO₈(936.37): calcd. C 58.92, H

6.23, N 14.94; found C 58.92, H 6.12, N 14.91.

X-ray Crystal Structure Analysis of 4d·Ni(NO₃)₂:^[13]Formula

C₄₆H₅₈N₁₀NiO₈·2CHCl₃, M = 1176.47, green crystal 0.35ϫ0.30ϫ

0.30 mm, a = 11.915(1), b = 19.990(1), c = 23.904(1) Å, β =

100.57(1)°, V = 5596.9(6) Å³, ρ_{ca lc d.}= 1.396 g cm^{– 3}, µ =

0.692 mm^–1, empirical absorption correction (0.794ՅTՅ0.819), Z

= 4, monoclinic, space group P2₁/c (No. 14), λ = 0.71073 Å, T =

198 K, ω and φ scans, 47247 reflections collected (Ϯh, Ϯk, Ϯl),

[(sinθ)/λ] = 0.66 Å^–1, 13259 independent (R_int= 0.055) and 9464

observed reflections [IՆ2σ(I)], 670 refined parameters, R = 0.053,

wR²= 0.148, max./min. residual electron density 1.16/–0.57 eÅ^–3,

hydrogen atoms at N from difference Fourier calculations, others

calculated and all refined as riding atoms.

¯

group P1 (No. 2), λ = 0.71073 Å, T = 198 K, ω and φ scans, 25540

reflections collected (Ϯh, Ϯk, Ϯl), [(sinθ)/λ] = 0.66 Å^–1, 10912 inde-

pendent (R_int= 0.054) and 8787 observed reflections [IՆ2σ(I)],

603 refined parameters, R = 0.045, wR²= 0.116, max./min. residual

electron density 0.42/–0.46 eÅ^–3, hydrogen atoms at N4 from dif-

ference Fourier calculations, others calculated and all refined as

riding atoms.

(2,6-Bis{[5-(diethylamino)-1,3-diphenyl-2,4-diaza-6-oxa-1,3,5-

hexatrienyl]amino}pyridine)dipalladium(II) Tetrachloride

(6·2PdCl₂): 6 (36 mg, 0.05 mmol) and bis(benzonitrile)palladi-

um(II) dichloride (39 mg, 0.1 mmol) were dissolved in acetonitrile

(1.9 mL). After centrifugation to remove any precipitate, diethyl

ether was allowed to diffuse into the solution. After 1 week, orange

crystals were formed. Yield: 34 mg (0.03 mol, 63%), m.p. 218 °C.

{N,NЈ-Bis[5-(diethylamino)-1,3-diphenyl-2,4-diaza-6-oxa-1,3,5-hexa-

trienyl]-1,2-trans-cyclohexanediamine}nickel(II) Dinitrate

[4h·Ni(NO₃)₂]: Ligand 4h (36 mg, 0.05 mmol) and nickel(II) nitrate

(29 mg, 0.1 mmol) were dissolved in acetonitrile (2 mL). After cen-

trifugation to remove undissolved residues, diethyl ether was al-

lowed to diffuse into the solution. Green crystals were formed over-

night. After 5 d, they were collected, washed with diethyl ether and

dried under reduced pressure. Yield: 37 mg (0.04 mmol, 88%),

IR (KBr): ν = 3486 (m, NH), 3060 (m, CH_arom.), 3037 (m,

˜

CH_arom.), 2968 (m, CH_aliph.), 2927 (s, CH_aliph.), 2862 (m, CH_aliph.),

2854 (m, CH_aliph.), 2360 (m), 2341 (m), 1703 (vs, C=O), 1625

(s,C=O), 1598 (s, C=N), 1564 (s, C=N), 1546 (vs, C=N), 1512 (s,

C=N), 1492 (s, C=C), 1466 (vs, C=C), 1382 (m), 1344 (m), 1299

(m), 1261 (s), 1240 (s), 1218 (m), 1178 (w), 1136 (m), 1093 (m),

1026 (m), 981 (w), 889 (w), 823 (w), 765 (m), 700 (m) cm^–1. MS

(ESI): m/z = 1034 [C₄₃H₄₅Cl₃N₉O₂Pd₂]⁺, 1000 [C₄₃H₄₄N₉O₂-

PdCl₂]⁺, 824 [C₄₃H₄₄N₉O₂Pd]⁺. C₄₃H₄₅Cl₄N₉O₂Pd₂(1071.05):

calcd. C 48.06, H 4.22, N 11.73; found C 48.21, H 4.48, N 11.24.

green crystals, m.p. 205 °C. IR (KBr): ν = 3255 (m, NH), 3091 (w,

˜

CH_arom.), 3060 (w, CH_arom.), 3033 (w, CH_arom.), 2974 (m, CH_aliph.),

2931 (m, CH_aliph.), 2858 (s, CH_aliph.), 1652 (s, C=O), 1625 (s, C=O),

1604 (s, C=N), 1579 (s, C=N), 1560 (s, C=N), 1496 (s, C=N), 1458

(s, C=C), 1384 (vs, C=C), 1299 (s), 1278 (s), 1218 (w), 1139 (w),

1097 (w), 1078 (w), 1024 (w), 773 (w), 730 (w), 700 (m) cm^–1. MS

(ESI): m/z (%) = 844 [C₄₄H₅₂N₉NiO₅]⁺, 781 [C₄₄H₅₁N₈NiO₂]⁺, 748

[C₄₄H₅₂N₈O₂+ Na]⁺, 726 [C₄₄H₅₂N₈O₂+ H]⁺. UV/Vis (acetoni-

X-ray Crystal Structure Analysis of (6·2PdCl₂):^[13]Formula

C₄₃H₄₅Cl₄N₉O₂Pd₂·2C₄H₁₀O·CH₃CN, M = 1263.77, orange crystal

0.35 ϫ 0.20 ϫ 0.10 mm, a = 13.202(1), b = 15.628(1), c =

28.043(1) Å, β = 98.16(1)°, V = 5727.3(6) Å³, ρ_calcd.= 1.466 gcm^–3,

µ = 0.867 mm^–1, empirical absorption correction (0.751 Յ T Յ

0.918), Z = 4, monoclinic, space group P2₁/n (No. 14), λ =

0.71073 Å, T = 198 K, ω and φ scans, 28887 reflections collected

trile): λ_max.(ν , ε) = 237 (42194 cm^–1, 41000 ^–1cm^–1) nm.

˜

C₄₆H₅₆N₈NiO₄(842.37): calcd. C 58.48, H 6.08, N 14.83; found C

58.86, H 6.00, N 14.92.

X-ray Crystal Structure Analysis of 4h·Ni(NO₃)₂:^[13]Formula

C₄₄H₅₂N₈NiO₂·2NO₃, M = 907.67, green crystal 0.40 ϫ0.35ϫ

0.20 mm, a = 22.106(1), b = 12.231(1), c = 18.015(1) Å, β =

97.14(1)°, V = 4833.1(5) Å³, ρ_calcd.= 1.247 gcm^–3, µ = 0.461 mm^–1,

empirical absorption correction (0.837ՅTՅ0.914), Z = 4, mono-

clinic, space group P2₁/c (No. 14), λ = 0.71073 Å, T = 198 K, ω

and φ scans, 32485 reflections collected (Ϯh, Ϯk, Ϯl), [(sinθ)/λ] =

0.67 Å^–1, 11935 independent (R_int= 0.047) and 8256 observed re-

(Ϯh, Ϯk, Ϯl), [(sinθ)/λ] = 0.62 Å^–1, 11369 independent (R_int

=

0.072) and 7879 observed reflections [IՆ2σ(I)], 623 refined param-

eters, R = 0.063, wR²= 0.183, max./min. residual electron density

1.56/–0.81 eÅ^–3, hydrogen atoms at N from difference Fourier cal-

culations, others calculated and all refined as riding atoms.

(Aqua)[bis(2-{[5-(diethylamino)-1,3-diphenyl-2,4-diaza-6-oxa-1,3,5-

hexatrienyl]amino}ethyl)(2-{[1,3-diphenyl-2-aza-4-oxa-1,3-

butadienyl]amino}ethyl)amine]nickel(II) Bis(perchlorate) (9): To a

solution of 7a (53 mg, 0.05 mmol) and nickel(II) perchlorate

(36 mg, 0.1 mmol) in methanol (1.9 mL) triethylamine (50 µL) was

flections [I Ն 2 σ(I)], 600 refined parameters, R = 0.068, wR²

=

0.237, max./min. residual electron density 1.43/–0.62 eÅ^–3, hydro-

gen atoms at N from difference Fourier calculations, others calcu-

lated and all refined as riding atoms.

Eur. J. Org. Chem. 2008, 5740–5754

www.eurjoc.org

5753

J.-B. Greving, H. Behrens, R. Fröhlich, E.-U. Würthwein

FULL PAPER

[3] H. Behrens, R. Fröhlich, E.-U. Würthwein, Eur. J. Org. Chem.

2005, 3891–3899.

[4] N. Hesse, R. Fröhlich, I. Humelnicu, E.-U. Würthwein, Eur. J.

Inorg. Chem. 2005, 2189–2197.

[5] J. K. Eberhardt, R. Fröhlich, E.-U. Würthwein, J. Org. Chem.

2003, 68, 6690–6694.

[6] a) H. V. R. Dias, S. Singh, Inorg. Chem. 2004, 43, 5786–5788;

b) H. V. R. Dias, S. Singh, Angew. Chem. 2005, 117, 4985–4988;

Angew. Chem. Int. Ed. 2005, 44, 4907–4910.

added at 55 °C. After 2 h at 55 °C, the reaction mixture was cooled

slowly to room temperature, and diethyl ether was added to the

resulting solution to form an upper layer. After 2 d, colourless crys-

tals of 9 were collected. Yield: 23 mg (0.02 mmol, 37%), colourless

crystals, m.p. 172 °C. IR (KBr): ν = 3286 (m, NH), 3062 (m,

˜

CH_arom.), 2976 (m, CH_arom.), 2933 (m, CH_aliph.), 2875 (m, CH_aliph.),

1676 (s, C=O), 1618 (vs, C=O), 1600 (s, C=N), 1577 (s, C=N), 1510

(s, C=C), 1488 (vs, C=C), 1446 (vs), 1427 (vs), 1379 (s), 1271 (s),

1107 (vs), 1093 (vs), 916 (vw), 775 (w), 711 (w), 698 (m) cm^–1. MS

[7]

[8]

[9]

H. Ley, F. Müller, Ber. Dtsch. Chem. Ges. 1907, 40, 2950–2958.

R. Fuks, M. Strebelle, A. Wenders, Synthesis 1977, 788–799.

M. Buhmann, M. H. Möller, U. Rodewald, E.-U. Würthwein,

Angew. Chem. 1994, 106, 2386–2389; Angew. Chem. Int. Ed.

Engl. 1994, 33, 2337–2339.

(MALDI): m/z (%)

=

1123 [C₅₈H₆₄N₁₁NiO₃]⁺, 510.9

[C₅₈H₆₅N₁₁NiO₃]²⁺

.

C₅₈H₆₇Cl₂N₁₁NiO₁₂·2ClO₄·2C₄H₁₀O·MeOH

(1420.12): calcd. C 56.67, H 6.46, N 10.85; found C 56.39, H 6.13,

N 11.09.

[10]

[11]

[12]

[13]

M. Al-Talib, H. Tashtoush, J. Heterocycl. Chem. 1988, 25,

X-ray

[N(C₂₁H₂₅N₄O₂)₂(C₁₆H₁₅N₂O)]Ni·H₂O·2ClO₄·2C₄H₁₀O·CH₃OH,

1420.12, colourless crystal 0.30ϫ0.30ϫ0.20 mm,

Crystal

Structure

Analysis

of

9:^[13]

Formula

1023–1028.

H. Tashtoush, M. Al-Talib, Recl. Trav. Chim. Pays-Bas 1991,

110, 75–77.

E. A. Marihart, J.-B. Greving, R. Fröhlich, E.-U. Würthwein,

Eur. J. Org. Chem. 2007, 5071–5081.

M

=

a =

14.410(1), b = 14.851(1), c = 18.958(1) Å, α = 80.35(1), β =

74.70(1), γ = 68.85(1)°, V = 3637.8(4) Å³, ρ_calcd.= 1.296 gcm^–3, µ

= 0.410 mm^–1, empirical absorption correction (0.887ՅTՅ0.923),

Data sets were collected with Enraf Nonius CAD4 and Nonius

KappaCCD diffractometers, in case of Mo radiation equipped

with a rotating anode generator. Programs used: data collection

EXPRESS (Nonius B. V., 1994) and COLLECT (Nonius B. V.,

1998), data reduction MolEN (K. Fair, Enraf–Nonius B. V.,

1990) and Denzo-SMN (Z. Otwinowski, W. Minor, Methods

Enzymol. 1997, 276, 307–326) and Denzo (Z. Otwinowski, D.

Borek, W. Majewski, W. Minor, Acta Crystallogr., Sect. A 2003,

59, 228–234), structure solution SHELXS-97 (G. M. Sheldrick,

Acta Crystallogr., Sect. A 1990, 46, 467–473), structure refine-

ment SHELXL-97 (G. M. Sheldrick, Acta Crystallogr., Sect.

A 2008, 64, 112–122), graphics SCHAKAL (E. Keller, 1997).

CCDC-694201 (for 5d), -694202 (for 5f), -694203 (for

3a·CoCl₂), -694204 (for 3a·ZnBr₂), -694205 (for 3b·ZnBr₂),

-694206 (for 3b·CuCl₂), -694207 [for 4b·Ni(ClO₄)₂], -694208

(for 4g), -694209 [for 4d·Ni(NO₃)₂], -694210 (for 6b), -694211

[for 7a·Ni(ClO₄)₂], -694212 [for 6·Ni(NO₃)₂], -694213 (for 4h),

-694214 [for 4h·Ni(NO₃)₂], -694215 (for 6·2PdCl₂) -694348 (for

4b) and -697731 (for 1d) contain the supplementary crystallo-

graphic 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.

¯

Z = 2, triclinic, space group P1 (No. 2), λ = 0.71073 Å, T = 198 K,

ω and φ scans, 40555 reflections collected (Ϯh, Ϯk, Ϯl), [(sinθ)/λ]

= 0.60 Å^–1, 12810 independent (R_int= 0.056) and 8751 observed

reflections [IՆ2σ(I)], 893 refined parameters, R = 0.063, wR²

=

0.191, max./min. residual electron density 1.74/–0.55 eÅ^–3, hydro-

gen atoms at N and water from difference Fourier calculations,

others calculated and all refined as riding atoms.

Acknowledgments

The authors thank the Deutsche Forschungsgemeinschaft (Son-

derforschungsbereich 424 and European Graduate College “Tem-

plate Directed Chemical Synthesis”) and the Fonds der Chemi-

schen Industrie (Frankfurt) for financial support.

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yer, H. J. Schäfer, E. Schmälzlin, C. Bräuchle, K. Meerholz, E.-

U. Würthwein, Eur. J. Org. Chem. 2003, 1198–1208.

[2] N. C. Aust, A. Beckmann, R. Deters, R. Krämer, L. Terfloth,

S. Warzeska, E.-U. Würthwein, Eur. J. Inorg. Chem. 1999,

1189–1192.

[14]

W. Schroth, H. Kluge, Z. Chem. 1986, 26, 94–95.

Received: August 8, 2008

Published Online: October 27, 2008

5754

www.eurjoc.org

Eur. J. Org. Chem. 2008, 5740–5754

Article Doi

Multivalent 1-Oxa-3,5,7-triazahepta-1,3,5-trienes: Synthesis, structural properties and metal coordination

DOI: 10.1002/ejoc.200800778

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