Conformational dependence of through-space tellurium-tellurium spin-spin coupling in peri-substituted bis(tellurides)

DOI: 10.1002/chem.201405599

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Conformation Analysis |Hot Paper|

Conformational Dependence of Through-Space Tellurium–

Tellurium Spin–Spin Coupling in Peri-Substituted Bis(Tellurides)

Fergus R. Knight, Louise M. Diamond, Kasun S. Athukorala Arachchige, Paula Sanz Camacho,

Rebecca A. M. Randall, Sharon E. Ashbrook, Michael Bꢀhl, Alexandra M. Z. Slawin, and

J. Derek Woollins*^[a]

Abstract: Three related series of peri-substituted bis(tellur-

ides) bearing naphthalene, acenaphthene and acenaphthy-

lene backbones (Nap/Acenap/Aceyl(TeY)₂(Nap=naphtha-

lene-1,8-diyl N; Acenap=acenaphthene-5,6-diyl A; Aceyl=

acenaphthylene-5,6-diyl Ay; Y=Ph 1; Fp 2; Tol 3; An-p 4;

An-o 5; Tp 6; Mes 7; Tip 8) have been synthesised and their

solid-state structures determined by X-ray crystallography.

Molecular conformations were classified as a function of the

two C9-C-Te-C(Y) dihedral angles (q); in the solid all mem-

bers adopt AB or CCt configurations, with larger Te(aryl) moi-

eties exclusively imposing the CCt variant. Exceptionally

large J(¹²⁵Te,¹²⁵Te) spin–spin coupling constants between

3289–3848 Hz were obtained for compounds substituted by

bulky Te(aryl) groups, implying these species are locked in

a CCt-type conformation. In contrast, compounds incorpo-

rating smaller Te(aryl) moieties are predicted to be rather dy-

namic in solution and afford much smaller J values (2050–

2676 Hz), characteristic of greater populations of AB con-

formers with lower couplings. This conformational depend-

ence of through-space coupling is supported by DFT calcula-

tions.

acteristically large J values for formally four-bond (⁴J) and even

longer coupling.^[1,4–9]Naturally, the extent of through-space

spin–spin coupling is determined by the strength of the lone-

pair interaction, which relies on the efficient overlap of orbitals,

and is thus strongly dependent on the internuclear dis-

tance.^[1–4]

Introduction

Spin–spin coupling constants (SSCCs) provide valuable infor-

mation about the environment surrounding coupled atomic

nuclei within a molecule and are becoming an increasingly im-

portant tool for analysing structures. The extent of spin–spin

coupling is governed by the amount of contact between nu-

clear magnetic dipoles and gives an insight into the underlying

connectivity and spacial arrangement of the coupled atoms.^[1–4]

Indirect (scalar) coupling is transmitted by the intervening net-

work of bonds linking the coupled nuclei (through-bond cou-

pling) and is thus dependent upon the degree of s-orbital par-

ticipation in the bonding and the polarisability of the s-elec-

trons. Through-bond coupling naturally recedes as additional

bonds are added and the nuclei become more detached, with

coupling through more than four bonds rarely observed.^[1–4]

Nevertheless, when NMR active atomic nuclei are forced to

lie within the sum of their van der Waals radii, but still remain

many bonds apart (formally non-bonded), additional coupling

can be transmitted through the interaction of overlapping

lone-pair orbitals (through-space coupling), leading to unchar-

Several studies of J(¹⁹F,¹⁹F) SSCCs have been undertaken to

try and quantify the dependency of through-space J_FFcoupling

and the intramolecular non-bonding distance d_FF.^[5–7]For exam-

ple, Mallory and co-workers derived an exponential correlation

of d_FFand J_FFfor a series of 1,8-difluoronaphthalenes (A&B;

Figure 1) which exhibit exceptionally large J(¹⁹F,¹⁹F) SSCCs in

the range 65–85 Hz.^[6]In these compounds, the exocyclic CÀF

bonds are coplanar and align virtually parallel, resulting in F···F

separations of around 2.58 ꢁ (r_vdW(F) 1.35 ꢁ).^[10]Interestingly,

the 1,8-difluoroacenaphthylenes investigated as part of the

study, containing a semi-rigid unsaturated ethene bridge, did

not conform to the correlation and were subsequently omit-

ted. Acenaphthenes with significant double bond character as-

sociated with their saturated ethane linkers similarly afforded

anomalous J_FFvalues and were also excluded. The deviation

observed for these derivatives compared to the remaining

members of the series was attributed to the difference in aro-

maticity of the acenaphthylene backbone and a greater inter-

action between the fluorine lone-pair orbitals and the p-

system. Confirmed by a later DFT study, the elevated J_FFvalues

resulted from a greater through-bond contribution to the over-

all coupling due to the increased p-interactions, subsequently

causing the observed deviation from the d_FF/J_FFexponential

curve.^[6]

[a] Dr. F. R. Knight, Dr. L. M. Diamond, Dr. K. S. A. Arachchige, P. Sanz Camacho,

R. A. M. Randall, Prof. S. E. Ashbrook, Prof. M. Bꢀhl, Prof. A. M. Z. Slawin,

Prof. J. D. Woollins

EaStCHEM School of Chemistry and Centre for Magnetic Resonance

University of St Andrews

St Andrews, KY16 9ST (UK)

E-mail: jdw3@st-andrews.ac.uk

Supporting information for this article is available on the WWW under

http://dx.doi.org/10.1002/chem.201405599.

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sional (2D) plot of potential energy as a function of the two C-

C-Te-C_Medihedral angles displayed a vast area within just 1 kcal

mol^À1which extended from the global minimum (CCt) into the

region classified as AB.^[11]In their study of corresponding sele-

nium derivatives, Nakanishi and colleagues concluded that this

small energy difference must result in an equilibrium existing

between the AB and CCt conformers in solution.^[9]This hypoth-

esis was supported in our own study, in which the experimen-

tally observed J value for Acenap(TePh)₂(2110 Hz; G, Figure 1)

was found to lie intermediate between the predicted

⁴J(¹²⁵Te,¹²⁵Te) SSCCs for the two conformers (CCt 2604 Hz; AB

1543 Hz).^[11]

Interestingly, when the phenyl moiety was replaced by

a much larger mesityl group (H, Figure 1), a conformational

change was observed in the solid from AB to CCt, and despite

only a 0.03 ꢁ reduction in the Te···Te internuclear distance, this

4

was accompanied by a significant increase in the J(¹²⁵Te,¹²⁵Te)

through-space coupling (3398 Hz).^[11]This implies that the ef-

fective overlap of the interacting lone-pairs and hence the size

of the SSCCs, depends not only on the internuclear distance,

but also on the orientation of the lone-pairs and hence the

conformation of the molecule. It therefore transpires that

through-space spin–spin coupling not only probes the bond-

ing situation between coupled nuclei, but also has the poten-

tial as an analytical tool for distinguishing between different

structural conformers of a molecule.

Figure 1. Systems exhibiting through-space spin–spin coupling between

closely aligned, but formally non-bonded NMR active nuclei.

Whilst the efficiency of lone-pair orbital overlap, and the

magnitude of through-space coupling, is greatly influenced by

the non-bonded internuclear distance, it is also sensitive to the

angular orientation of the overlapping lone-pairs. For instance,

4,5-difluorophenanthrene derivatives of type C (Figure 1), in

which the exocyclic CÀF bonds are no longer coplanar, nor

parallel, produce much larger J(¹⁹F,¹⁹F) SSCCs than their naph-

thalene equivalents, with J values of 165–175 Hz truly massive

for formally five-bond (⁵J_FF) couplings.^[6]

The current study aims to develop our understanding of the

conformational dependence of through-space spin–spin cou-

pling by investigating how the electronics and sterics of sub-

stituents at Te and the architecture of the backbone, can mod-

ulate the molecular structures, intramolecular bonding interac-

tions and NMR properties in a series of peri-substituted bis(tel-

lurides). For our study we chose to compare 1,8-disubstituted

naphthalenes N with bridged acenaphthene A and acenaph-

thylene Ay systems, in total synthesising 23 bis(tellurides);

With the aid of quantum-chemical computations, torsional

angular dependence of ¹J(⁷⁷Se,⁷⁷Se) spin–spin coupling has

been predicted in a model diselenide, MeSeSeMe, justifying

the substantial J values (331–379 Hz) observed experimentally

for restricted naphtho[1,8-c,d]-1,2-diselenoles of type

D

Nap/Acenap/Aceyl(TeY)₂

(Nap=naphthalene-1,8-diyl

N;

(Figure 1).^[9]In the same study, substantial J(⁷⁷Se,⁷⁷Se) coupling

constants of equivalent or even greater magnitude were re-

ported for naphthalenes containing non-bonded Se···Se

(332 Hz) and O=Se···Se=O (456 Hz) interactions (E, Figure 1),

Acenap=acenaphthene-5,6-diyl A; Aceyl=acenaphthylene-

5,6-diyl Ay; Y=Ph 1; Fp 2; Tol 3; An-p 4; An-o 5; Tp 6; Mes 7;

Tip 8; Figure 2).

4

the latter the largest known J-coupling between formally non-

bonded Se atoms. Further computational conformational anal-

ysis of through-space coupling in these systems revealed

4

a striking difference in the predicted J(Se,Se) values depend-

ing on the conformation of the optimized structure of the mol-

4

ecule. For example, calculated J(Se,Se) SSCCs for the four opti-

mized structures of Nap(SeMe)₂span a range between 19.5–

564.8 Hz.^[9]

Our own detailed conformational analyses of the related

bis(tellurium) compound Nap(TeMe)₂(F, Figure 1) revealed

4

a similar conformational dependence of J(Te,Te) through-space

4

coupling, with a dramatic change in the magnitude of J(Te,Te)

SSCCs predicted upon subtle changes to the structural confor-

mation.^[11]The optimised CCt conformer (vide infra) is the

4

global minimum and is predicted to have J(¹²⁵Te,¹²⁵Te) values

around 2500 Hz, whilst a conformer in the AB region is predict-

ed to have a much lower J value (ca. 1500 Hz). A two-dimen-

Figure 2. Peri-substituted bis(tellurides) N1–N8, A1–A8 and Ay1–Ay8.

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In these compounds the tellurium moieties are formally

non-bonded, but lie at distances significantly shorter than the

sum of van der Waals radii, inducing weak donor-acceptor 3-

center-4-electron (3c–4e) interactions to transpire, reinforcing

the through-space coupling and leading to exceptionally large

⁴J(¹²⁵Te,¹²⁵Te) SSCCs.^[11–14]Considering the shortest through-

bond pathway connecting the two tellurium atoms in these

systems is four bonds long, it was assumed that the contribu-

tion from through-bond coupling would be sufficiently small

Scheme 2. Preparation of acenaphthenes A1–A8 and acenaphthylenes Ay1–

Ay8: i) TMEDA (2.6 equiv), nBuLi (2.4 equiv, dropwise), Et₂O, À10-08C, 1 h;

ii) RTeTeR (2 equiv), Et₂O, À788C, 1 h; iii) DDQ (1.5 equiv), benzene, reflux,

24 h.

enough to be able to determine experimentally the conforma-

[1–4,6]

tional dependence of J_TeTe

.

All compounds obtained were characterized by multinuclear

magnetic resonance and IR spectroscopies and mass spectrom-

etry, and the homogeneity of the new compounds was con-

firmed by microanalysis. ¹²⁵Te and ¹²³Te NMR spectroscopic

data for all three series of bis(telluride) derivatives and their re-

spective ditelluride starting materials is displayed in Table 1.

Results and Discussion

Synthetic aspects

The three corresponding series of peri-substituted aryl tellur-

ides were prepared from diaryl ditellurides bis(4-fluorophenyl)

ditelluride (FpTeTeFp), bis(4-methylphenyl) ditelluride (TolTeTe-

Tol), bis(4-methoxyphenyl) ditelluride (An-pTeTeAn-p), bis(2-me-

thoxyphenyl) ditelluride (An-oTeTeAn-o), bis(4-tertbutylphenyl)

ditelluride (TpTeTeTp), bis(2,4,6-trimethylphenyl) ditelluride

(MesTeTeMes) and bis(2,4,6-triisopropanylphenyl) ditelluride

(TipTeTeTip).^[15]Naphthalenes N2–N8 were prepared by follow-

ing the same procedure to that previously reported for the

synthesis of 1,8-bis(phenyltelluro)naphthalene N1;^[12]under an

oxygen- and a moisture-free nitrogen atmosphere, 1,8-diiodo-

naphthalene was independently treated with two molar equiv-

alents of n-butyllithium in diethyl ether to afford the precursor

1,8-dilithionaphthalene, which when reacted with the appro-

priate diaryl ditelluride afforded N2–N8 in moderate to good

yield (yield: 65 (N2), 13 (N3), 45 (N4), 15 (N5), 51 (N6), 11 (N7),

26% (N8); Scheme 1).

Table 1. ¹²⁵Te and ¹²³Te NMR spectroscopy data.

RTeTeR

Ph

Fp

Tol

An-P An-o Tp

Mes

Tip

¹²⁵Te NMR

¹²³Te NMR

428

434

463

464

129

156

N2

432

787

949

N3

461

216

260

N4

176

279

336

N5

409

410

198

239

N6

202

532

642

N7

183

650

784

N8

J(¹²³Te,¹²⁵Te) 268

J(¹²⁵Te,¹²⁵Te) 323

N1^[12]

620

¹²⁵Te NMR

¹²³Te NMR

616

608

607

602

515

514

604

605

397

346

J(¹²³Te,¹²⁵Te) 2077

J(¹²⁵Te,¹²⁵Te) 2505

A1^[13]

2082 2145 2189 2219 2097 3191 3095

2511 2587 2640 2676 2529 3848 3733

A2

A3

A4

A5

A6

A7

A8

¹²⁵Te NMR

¹²³Te NMR

586

587

582

580

574

568

482

571

572

363

316

J(¹²³Te,¹²⁵Te) 1750

J(¹²⁵Te,¹²⁵Te) 2110

1746 1780 1835 1796 1766 2818 2727

2106 2147 2213 2166 2130 3398 3289

Ay1^[14]Ay2

619

Ay3

606

605

Ay4

541

–

Ay6

601

600

Ay7

407

406

Ay8

354

353

¹²⁵Te NMR

¹²³Te NMR

610

J(¹²³Te,¹²⁵Te) 1706

J(¹²⁵Te,¹²⁵Te) 2057

1700 1796

2050 2166

1772 2956 2958

2137 3565 3567

–

X-ray investigations

Scheme 1. Preparation of naphthalenes N1–N8: i) nBuLi (2.03 equiv, drop-

wise), Et₂O, À788C, 1 h; ii) RTeTeR (2 equiv), Et₂O, À788C, 1 h.

Suitable single crystals were obtained for N2–N7, A2–A7 and

Ay2 by diffusion of hexane into a saturated solution of the

compound in dichloromethane. Crystals for Ay3, Ay4, Ay7 and

Ay8 were obtained by evaporation of a dichloromethane solu-

tion of the product, for A8 by evaporation of a hexane solution

and similarly for Ay5 from a chloroform solution. All com-

pounds contain only one molecule in the asymmetric unit. Se-

lected interatomic bond lengths and angles are listed in Tables

S1–S3 (Supporting Information) and further crystallographic in-

formation can be found in the Supporting Information.

Acenaphthenes A2–A8 were synthesised by following

a slightly modified route, instead proceeding by a 5,6-dilithioa-

cenaphthene·2TMEDA intermediate complex, as previously de-

scribed for the preparation of 5,6-bis(phenyltelluro)acenaph-

thene A1 (yield: 54 (A2), 38 (A3), 53 (A4), 39 (A5), 61 (A6), 22

(A7), 54% (A8); Scheme 2).^[13]Except for A5, treatment of the

respective acenaphthene derivative with 2,3-dichloro-5,6-dicya-

no-1,4-benzoquinone (DDQ) in refluxing benzene^[14]resulted in

the effective dehydrogenation of the ethane backbone, afford-

ing the corresponding acenaphthylene derivative Ay2–Ay4,

Ay6–Ay8 (yield: 18 (Ay2), 23 (Ay3), 23 (Ay4), 12 (Ay6), 9 (Ay7),

14% (Ay8); Scheme 2).

The molecular structures of peri-substituted systems are reg-

ularly categorised using the classification system devised by

Nakanishi et al.^[16]and Nagy et al.,^[17]whereby the conformation

of the peri-atom-substituent bond (with respect to the mean

plane of the organic backbone) is described as either perpen-

dicular (A or axial), coplanar (B or equatorial) or intermediate

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Table 2. Torsion angles [8] categorising the aromatic-ring conformations

in N1–N8, A1–A8 and Ay1–Ay8.

Comp.

C(10)-C(1)-Te(1)-C(11)

C(10)-C(9)-Te(2)-C(18)

N1

N2

N3

N4

N5

N6

N7

q₁À124.79(1) twist^[c]

q₁À145.4(4) twist

q₁À148.5(4) twist

q₁À125.1(8) twist

q₁177.2(6) equatorial^[b]

q₁À77.0(3) axial^[a]

q₁138.8(4) twist

q₂À132.46(1) twist

q₂À146.2(4) twist

q₂À149.4(4) twist

q₂À134.8(8) twist

q₂À110.1(6) axial

q₂À169.3(3) equatorial

q₂À142.8(4) twist

CCt

AB

CCt

Comp.

C(10)-C(1)-Te(1)-C(13)

C(10)-C(9)-Te(2)-C(19)

A1

A2

A3

A4

A5

A6

A7

A8

q₁166.60(1) equatorial

q₁À167.3(6) equatorial

q₁À153.3(5) twist

q₂79.56(1) axial

q₂À80.3(5) axial

q₂À142.0(5) twist

q₂144.2(9) twist

q₂À84.4(4) axial

q₂72.5(8) axial

q₂À136.4(6) twist

q₂À169.4(4) equatorial

AB

CCt

AB

CCt

BCc

q₁153.3(9) twist

q₁À165.8(4) equatorial

q₁169.3(6) equatorial

q₁À152.1(6) twist

q₁142.6(4) twist

Figure 3. The absolute conformation of aromatic rings is calculated from tor-

sion angles q (defining rotation around the TeÀC_’Nap’bond) and classified by

types A (axial, perpendicular), B (equatorial, planar) or C (twist).^[16,17]

Comp.

C(10)-C(1)-Te(1)-C(13)

C(10)-C(9)-Te(2)-C(19)

Ay1

Ay2

Ay3

Ay4

Ay6

Ay7

Ay8

q₁78.8(7) axial

q₂166.2(7) equatorial

q₂90.5(3) axial

q₂145.7(9) twist

q₂À152.0(7) twist

q₂À164.5(19) equatorial

q₂152.9(7) twist

AB

q₁165.4(3) equatorial

q₁152.2(9) twist

q₁À142.6(7) twist

q₁68.2(17) axial

q₁145.3(7) twist

q₁133.1(3) twist

CCt

AB

CCt

between these two scenarios (C or twist; Figure 3). A double

substitution can subsequently result in either a cis (c) or trans

(t) arrangement of the two substituent bonds relative to the

naphthalene plane. The absolute conformation of the Te(aryl)

groups is calculated from torsion angles q, which defines the

degree of rotation around each TeÀC_’Nap’bond (Table 2,

Figure 3).

q₂133.1(3) twist

[a] axial: perpendicular to C(ar)-Te-C(ar) plane. [b] equatorial: coplanar

with C(ar)-Te-C(ar) plane. [c] twist: intermediate between axial and equa-

torial.

In the solid, all bis(tellurides) investigated as part of this

study adopt either a CCt conformation, similar to what is

found for N1^[11,12]and A7,^[11]or an AB conformation compara-

ble to that observed for A1^[11,13](Figure 3–5, Table 2). Com-

pound A8 (Tip) is the one anomaly in the series, adopting

a slightly modified BCc type arrangement in the solid (Figure 5,

Table 2). The structural variation observed in the solid for this

family of compounds is consistent with the conformational

is shown to increase in the order 81 (Ph, Fp, Tol, An-p, Tp)<

105 (An-o)<123 (Mes)<1348 (Tip), which helps to illustrate

the lack of correlation between the size of the substituents

bound to Te and the conformation adopted in the solid. For in-

stance, Te(Tol) (3) and Te(An-p) (4) derivatives favour CCt con-

formations, contrasting with the AB conformation imposed by

the similarly sized Te(Tp) (6) moiety. It is worth noting, howev-

er, that derivatives substituted with larger moieties, such as

Te(Mes) (7) and Te(Tip) (8), prefer to adopt CCt conformations

in the solid, a result which became more apparent during the

analysis of the solution-state structures (vide infra).

[11]

analysis carried out on Nap(TeMe)₂and related selenium de-

rivatives,^[9]which revealed that AB and CCt-type conformers

are the most stable and very close in energy (within 1 kcal

mol^À1), and as such can thus be controlled by subtle changes

to the steric and electronic properties of the peri-substituents.

Nevertheless, certain trends are observed across the three

series, with, for example, mesityl (Mes), para-anisole (An-p) and

toluene (Tol) derivatives invariably adopting CCt type arrange-

ments (Figure 4 and 5) and ortho-anisole (An-o) and tert-butyl-

phenyl (Tp) analogues favouring AB configurations (Figure 4

and 5). Whilst this suggests the nature of the Te(aryl) moiety

rather than the type of organic backbone dictates the final mo-

lecular conformation in these compounds, substituent size is

certainly not the only factor involved. The steric bulk of the

aryl functionalities can be quantified by measuring the Te(aryl)

group cone angle, with the steric parameter (q) defined as the

apex angle that extends from the hydrogen atoms at the ex-

treme edges of the cone to the central Te atom at the

vertex.^[18]Using this method, the steric bulk of the aryl groups

The double substitution of increasingly large atoms or

groups on a peri-backbone invariably causes greater repulsion

and an increase in steric pressure within the bay region due to

the overlap of closely aligned orbitals.^[19–21]With this in mind, it

would be expected that as larger Te(aryl) groups, such as

Te(Mes) (7) and Te(Tip) (8), are located at the proximal peri-po-

sitions greater deformation of the carbon framework would be

required to accommodate the extra bulk,^[19–21]as discovered re-

cently in a series of analogous tellurium–selenium acenaph-

thenes;^[18]however, no apparent correlation is found between

the steric bulk of the Te(aryl) functionality (steric parameter, q)

and the degree of molecular distortion occurring within the or-

ganic framework. Non-bonded Te···Te peri-separations for the

naphthalene series are within just 0.08 ꢁ and span a range

from 3.2623(7) ꢁ in N7 (Te(Mes); q=1208) to 3.3436(6) ꢁ in N6

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for the three series of bis(tellur-

ides) and whilst d_TeTevalues only

vary by 0.17 ꢁ, the effect each

organic backbone has on the

Te···Te interaction is clearly illus-

trated. Similar trends are ob-

served across all three series,

with Te(Mes) and Te(An-p) deriv-

atives providing the smallest

Te···Te separations and maximum

d_TeTevalues observed for Te(Tp)

analogues. Interestingly, CCt

conformers constantly exhibit

shorter Te···Te distances than AB

variants. This is consistent with

the findings from previous stud-

ies of related chalcogen-substi-

tuted compounds^[12–14]and the

computational

conformational

analysis previously carried out

on Nap(TeMe)₂.^[11]

For instance, the two-dimen-

sional (2D) Ramachandran-type

plot in Figure 7 represents the

nonbonded Te···Te peri-distance

in Nap(TeMe)₂as a function of

the two C9-C-Te-C(Me) dihedral

angles. Here a structure with CCt

conformation is computed to

have a relatively short peri-sepa-

ration of around 3.3 ꢁ, with

structures in the AB region pre-

dicted to have notably longer

Te···Te distances up to 3.5 ꢁ.^[11]

Whilst the computed values

from the computational analysis

of Nap(TeMe)₂are marginally

overestimated with respect to

experimental values obtained for

the three series, the predicted

tendency is confirmed qualita-

tively (Figure 8).

Figure 4. Molecular conformations of Te(Ph) (1), Te(Fp) (2), Te(Tol) (3) and Te(An-p) (4) derivatives substituted on

naphthalene (N), acenaphthene (A) and acenaphthylene (Ay) organic backbones, showing the orientation of the

substituents bound to Te. All compounds adopt either a CCt or AB configuration in the solid.

Despite the apparent confor-

mational dependence of d(Te,Te),

nonbonded Te···Te peri-distances

(Te(Tp); q=818). As expected,^[13,14]marginally longer Te···Te

peri-distances are observed in corresponding acenaphthene

(3.3204(15) ꢁ A4 Te(An-p)—3.933(13) ꢁ A6 Te(Tp)) and ace-

naphthylene (3.3337(12) ꢁ Ay4 Te(An-p)—3.437(3) ꢁ Ay6

Te(Tp)) derivatives due to the additional constraints of the

bridging ethane/ethene organic linkers that naturally widen

the bay region. Nevertheless, little variation is observed in d_TeTe

for different molecular conformations or Te(aryl) functionalities,

with separations differing by only 0.07 and 0.10 ꢁ in the two

series, respectively.

for all bis(tellurides) of this study are 17–21% shorter than

twice the van der Waals radii of Te (4.12 ꢁ).^[10]In all cases, the

close proximity of the tellurium atoms and the orientation of

the molecule provides the correct geometry to promote deloc-

alization of a tellurium lone pair to an antibonding s*(TeÀC_Ar)

orbital to form an energy-lowering, donor–acceptor three-

center–four-electron (3c–4e)-type interaction. Such nonbonded

interactions provide a convenient pathway through which

scalar J spin couplings can operate, and result in exceptionally

large through-space J(¹²⁵Te,¹²⁵Te) SSCCs.

The plot in Figure 6 displays the relationship between the

nonbonded Te···Te distance and the form of the Te(aryl) group

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between the two values arising

from subtle differences in the

molecular dynamics of the two

compounds in solution.^[11]In the

solid, N1^[11,12]and A1^[11,13]adopt

conformations in the CCt and AB

regions, but in solution both

compounds appear to be rather

fluxional due to the negligible

energy difference predicted be-

tween these two types of con-

formers.^[11]Considering such

a dramatic variation in through-

space J(¹²⁵Te,¹²⁵Te) spin–spin cou-

pling is achieved with only

a minor change to the confor-

mation (~1000 Hz between CCt

and AB),^[11]the relatively small

deviation observed in the

J

values for N1 and A1 is thus

likely to arise from subtle shifts

in conformer equilibrium, rather

than reflecting the conformation

of each compound in the solid.

By contrast, the truly massive

J(¹²⁵Te,¹²⁵Te) value of 3398 Hz ob-

tained for the mesityl derivative

A8,^[11]indicates a considerable

shift in the conformer popula-

tions in solution towards a CCt

type arrangement, now consis-

tent with the structure found in

the solid.^[11]

The plot in Figure 9 shows the

relationship between J(¹²⁵Te,¹²⁵Te)

and the aryl moiety for all three

series, again illustrating the

effect each backbone has on the

coupling value. Interestingly the

naphthalene series exhibits nota-

bly larger through-space cou-

pling compared to the values

obtained for corresponding ace-

naphthene and acenaphthylene

analogues, which is consistent

with the shorter Te···Te peri-dis-

Figure 5. Molecular conformations of Te(An-o) (5), Te(Tp) (6), Te(Mes) (7) and Te(Tip) (8) derivatives substituted on

naphthalene (N), acenaphthene (A) and acenaphthylene (Ay) organic backbones, showing the orientation of the

substituents bound to Te. All compounds except A8 adopt either a CCt or AB configuration in the solid.

Solution NMR spectroscopic studies

tances naturally found in naphthalene derivatives (Figure 6),

and thus shows a form of distance dependence on J_TeTe

.

For symmetrical systems, such as ditellurides or the series of

bis(tellurides) of this study, the magnetic equivalence of two Te

nuclei impedes direct observation of J(¹²⁵Te,¹²⁵Te) coupling in

solution-state ¹²⁵Te NMR spectra. Nevertheless, J(¹²⁵Te,¹²⁵Te)

values can be converted from experimentally obtained

J(¹²³Te,¹²⁵Te) coupling, detected as satellites in the ¹²³Te NMR

spectra. Using this technique, exceptionally large J(¹²⁵Te,¹²⁵Te)

SSCCs have previously been obtained for phenyl derivatives

N1 (2505 Hz) and A1 (2110 Hz), with the large discrimination

Within all three series a striking variation is observed in

through-space J(¹²⁵Te,¹²⁵Te) spin–spin coupling (2050-3848 Hz)

depending on the nature of the Te(aryl) functionality em-

ployed. For compounds substituted with smaller Te(aryl)

groups (Ph, Fp, Tol, An-p, An-o, Tp; q=81–1058), J(¹²⁵Te,¹²⁵Te)

values of 2505–2676 (N1–N6), 2106–2213 (A1–A6) and 2050–

2166 Hz (Ay1–Ay6) are found, whilst bulkier Mes and Tip deriv-

atives (q=123–1348) afford substantially higher

J values

(3289–3848 Hz). Because the J coupling changes so dramatical-

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Figure 6. Plot showing the variation in the nonbonded Te···Te peri’distances

~

&

for the three series of analogous bis(tellurides). : acenaphthylene; : ace-

*

naphthalene; : naphthalene.

Figure 7. Non-bonded Te···Te distances (B3LYP/SDD/6-31G* level) in Nap(-

TeMe)₂as a function of the conformation, as defined by the two C9-C-Te-

C(Me) dihedral angles (q).^[11]

ly with conformation,^[11]the extremely small range of SSCCs

found between Ph, Fp, Tol, An-p, An-o and Tp derivatives in all

three series (DJ_TeTeN1–N6 171 Hz; DJ_TeTeA1–A6 107 Hz; DJ_TeTe

Ay1–Ay6 116 Hz) indicates the conformational similarity of the

structures in solution. This is in stark contrast to their behav-

iour in the solid-state (vide supra), in which a mixture of AB

and CCt conformations are obtained, but it is consistent with

the theory that an equilibrium must exist between AB and CCt

conformers in solution due to the small difference in their po-

tential energies.^[10,11]In spite of this, an excellent correlation is

observed between the d(¹²⁵Te) values for the naphthalene

series and those of their acenaphthene analogues (Figure S3,

Supporting Information), which indicates that in solution the

structural conformation around the two Te atoms in related

compounds must be very close.^{[16 g]}

Figure 8. Experimentally obtained Te···Te peri-distances in naphthalene (top),

acenaphthene (middle) and acenaphthylene (bottom) derivatives as a func-

tion of the two C9-C-Te-C(R) dihedral angles.

Considering the J(¹²⁵Te,¹²⁵Te) values for the less bulky deriva-

tives are significantly smaller than for Mes and Tip analogues

(by 1057–1399 Hz), it is assumed that the conformer equilibri-

um is shifted towards greater populations of AB conformers,

and thus the J values obtained from solution-state NMR spec-

tra may not necessarily reflect the structural conformations

found in the solid for these compounds. Conversely, the excep-

tionally large J(¹²⁵Te,¹²⁵Te) values obtained for the Mes and Tip

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al information on both interactions. As an example, the ¹²⁵Te

spectra of compound Ay8 (at 9.4 T and 14.1 T) are shown in

Figure 10.

DFT calculations

To probe how well the findings from X-ray structural analysis

and solution-state NMR studies could be reproduced and ra-

tionalised computationally, and specifically to assess the extent

of conformational dependence of through-space J(¹²⁵Te,¹²⁵Te)

spin–spin coupling in these peri-substituted bis(telluride) sys-

tems, DFT calculations were performed for the phenyl (N1, A1,

Ay1), tolyl (N3, A3, Ay3), para-anisyl (N4, A4, Ay4) and mesityl

(N7, A7, Ay7) derivatives of this study (Table 3).

Figure 9. Plot showing the dramatic change in J(¹²⁵Te,¹²⁵Te) for different

members of all three series of bis(tellurides).

First, atomic coordinates obtained from X-ray crystallography

were optimized at the B3LYP/SDD/6-31G* level, which was

chosen for compatibility with our previous calculations on re-

lated bis(chalcogen) species.^[11–14]At this level all four naphtha-

lenes (N1, N3, N4 and N7) and the two additional mesityl de-

rivatives (A7 and Ay7) optimise to a CCt conformation in

which both dihedral angles (q) align close to 1408, correspond-

ing to the structure found in the solid in each case. In contrast,

both AB and CCt minima are found for the remaining acenaph-

thene (A1, A3, A4) and acenaphthylene (Ay1, Ay3, Ay4) deriva-

tives.

compounds are consistent with a CCt conformation in solu-

tion,^[11]in agreement with the molecular structures determined

by X-ray crystallography.

To the best of our knowledge, the value of 3848 Hz obtained

for N7 is the largest SSCC observed to date between formally

non-bonded Te atoms. In fact J(¹²⁵Te,¹²⁵Te) values with a mean

greater than 2000 Hz, as observed for all members of this

4

study, are quite considerable for formal J coupling. For com-

In all cases the computed Te···Te nonbonded peri-distance is

notably overestimated compared to that observed in the solid

(by up to 0.09 ꢁ); however, this is a common DFT problem and

a good linear correlation is found between the computed dis-

tances and those obtained experimentally from X-ray data (Fig-

1

parison, J through-bond SSCCs of only 156–949 Hz were ob-

tained for the parent ditellurides (RTeTeR; R=Ph, Fp, Tol, An-p,

An-o, Tp, Mes, Tip; Table 1),

Solid-state NMR spectroscopy

The crystal structure of com-

pound Ay8 contains one crystal-

lographically distinct molecule

per asymmetric unit, but the

two tellurium atoms within this

molecule are crystallography in-

equivalent, and so it is possible

to estimate the through-space J

coupling between the two peri

atoms using solid-state NMR

spectroscopy. However, the pres-

ence of a significant ¹²⁵Te chemi-

cal shift anisotropy (CSA) results

in a significant number of spin-

ning sidebands, hindering the

accurate analysis of both shield-

ing and coupling tensors.

Table 3. Selected bond distances (ꢁ) from X-ray crystallography and B3LYP optimisations (in brackets: Wiberg

bond indices at the B3LYP level) and J(¹²⁵Te,¹²⁵Te) couplings from solution-state NMR studies and ZORA-SO/BP//

B3LYP computations.

N1^[12]

N3

N4

N7

Aryl Group

Ph

Tol

An-p

Mes

Exptl. Te···Te [Conf.]

Calcd Te···Te [WBI] AB

CCt

Exptl. J(¹²⁵Te,¹²⁵Te)

Calcd J(¹²⁵Te,¹²⁵Te) CCt

3.287(1) [CCt]

n/a

3.341 [0.15]

2505

3.2706(8) [CCt]

n/a

3.351 [0.14]

2587

3.2657(15) [CCt]

n/a

3.355 [0.14]

2640

3.2623(7) [CCt]

n/a

3.356 [0.14]

3848

2779

3078

3191

3153

A1^[13]

A3

A4

A7

Aryl Group

Ph

Tol

An-p

Mes

Exptl. Te···Te [Conf.]

Calcd Te···Te [WBI] AB

CCt

Exptl. J(¹²⁵Te,¹²⁵Te)

Calcd J(¹²⁵Te,¹²⁵Te) AB

CCt

3.3674(19) [AB]

3.438 [0.13]

3.412 [0.13]

2110

1543

2604

3.3285(7) [CCt]

3.440 [0.13]

3.414 [0.13]

2147

1591

2699

3.3204(15) [CCt]

3.448 [0.13]

3.415 [0.13]

2213

1375

2842

3.3380(11) [CCt]

n/a

3.422 [0.12]

3398

n/a

2738

The splittings observed in the

isotropic peaks (at 354 and

316 ppm) although not com-

pletely resolved, can be estimat-

ed as between 3600 and

4000 Hz, although a more de-

tailed analysis would be re-

quired to extract the full tensori-

Ay1^[14]

Ay3

Ay4

Ay7

Aryl Group

Ph

Tol

An-p

Mes

3.3415(11) [CCt]

n/a

3.432 [0.11]

3565

Exptl. Te···Te [Conf.]

Calcd Te···Te [WBI] AB

CCt

Exptl. J(¹²⁵Te,¹²⁵Te)

Calcd. J(¹²⁵Te,¹²⁵Te) AB

CCt

3.393(3) [AB]

3.451 [0.13]

3.425 [0.12]

2057

1465

2798

3.3527(14) [CCt]

3.453 [0.13]

3.423 [0.12]

2166

1438

2879

3.3337(12) [CCt]

3.466 [0.12]

3.427 [0.12]

–

1317

2978

n/a

2918

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The first is made up by the three points on the right-hand

side representing the bulky mesityl derivatives N7, A7 and

Ay7, and whilst the observed couplings are significantly under-

estimated (systematically by ca. 650 Hz), the computed trend

fits well to the experimentally obtained J values. Theoretical J

values are, amongst other variables, rather sensitive to the

level of geometry optimization employed in the NMR calcula-

tion, and in line with previous results,^[11]going from B3LYP- to

PBE0-optimised geometries brings down the error to approxi-

mately 400 Hz (results not shown). Nevertheless, the computa-

tional results support the findings from X-ray data and solu-

tion-state NMR spectroscopy, which indicates that these three

bulky species are essentially locked in the CCt conformation.

The second region is comprised of the remaining naphtha-

lene species N1, N3 and N4. Similar to the three mesityl deriva-

tives, only a single minimum is found for each compound in

the region classed as CCt (corresponding to the structure

found in the solid) and correspondingly, computed J values are

naturally relatively large. In fact the couplings are significantly

overestimated with respect to experiment indicating these sys-

tems are quite dynamic and explore a significant region in

phase space extending toward AB conformers with their lower

couplings.^[11]The J coupling has been traced back to the over-

lap between the “sp²”-type lone pairs on the Te atoms.^[11]Ap-

parently this overlap is somewhat reduced in the AB conform-

ers compared to that in the CCt forms (see Figure S1 in the

Supporting Information).

Finally the third region formed by the clusters on the left

corresponds to the remaining acenaphthene and acenaphthy-

lene species substituted by Te(Ph), Te(Tol) and Te(An-p) groups.

Here we can find both AB and CCt minima, and the observed

couplings are “bracketed” by the values computed for CCt,

which are overestimated, and for AB, which are underestimat-

ed. Neither set shows any correlation with experiment, nor

does the 50:50 average between the two (* in Figure 11).

These species are thus predicted to be even “more dynamic”

than the second group and explore an even larger region in

phase space. The actual coupling is not only governed by the

“intrinsic” substituent effects, but will also depend on the dy-

namic averaging. On going from, for example, Ph to Tol to An-

p the aryl rings not only become more electron rich, their

moment of inertia is bound to change as well (i.e. the angular

momentum about the peri-Te bonds), and that may influence

the dynamics. Averaging the chemical shifts over long enough

trajectories from molecular dynamics simulations would be re-

quired to address this question more quantitatively, but this

would be a formidable computational effort exceeding the

scope of the present paper.

Figure 10. ¹²⁵Te solid-state (B₀=9.4 T) NMR spectra of Ay8, recorded using

a) MAS rates of 14 kHz. b) ¹²⁵Te solid-state (B₀=14.1 T); MAS rates of 14 kHz.

c) using MAS rates of 40 kHz (B₀=14.1 T).

ure S2, Supporting Information). Consistent with the findings

from our previous conformational analysis of Nap(TeMe)₂, the

trend towards longer Te···Te separations on going from CCt to

AB conformations is captured well in the computations for ace-

naphthenes (A1, A3, A4) and acenaphthylenes (Ay1, Ay3, Ay4),

with distances increasing by approximately 0.04 ꢁ. Neverthe-

less, the extent of covalent bonding between the two Te cen-

tres is predicted to be fairly similar throughout the three series

of compounds, with calculated Wiberg Bond Indices (WBI)^[22]

decreasing only marginally from 0.15–0.14 for the set of naph-

thalene compounds (N1, N3, N4, N7) to 0.13–0.11 for their ace-

naphthene and acenaphthylene analogues.

Conclusions

Next, computed (ZORA-SO/BP//B3LYP level) J(¹²⁵Te,¹²⁵Te)

SSCCs were obtained for all twelve compounds, including pre-

dicted J values for AB and CCt variants in which both conform-

ers are found. Figure 11 displays a plot of the computed versus

the experimental data, with three distinct regions clearly de-

fined.

A combination of X-ray crystallography, NMR spectroscopy and

DFT calculations has been used to investigate the conforma-

tional dependence of through-space J(¹²⁵Te,¹²⁵Te) spin–spin

coupling in three analogous series of peri-substituted bis(tellur-

ides); Nap/Acenap/Aceyl(TeY)₂(Nap=naphthalene-1,8-diyl N;

Acenap=acenaphthene-5,6-diyl A; Aceyl=acenaphthylene-

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lar conformation, the dynamics of species and thus their con-

former populations in solution.

Experimental Section

All experiments were carried out under an oxygen- and moisture-

free nitrogen atmosphere using standard Schlenk techniques and

glassware. Reagents were obtained from commercial sources and

used as received. Dry solvents were collected from a MBraun sol-

vent system. Elemental analyses were performed by Stephen Boyer

at the London Metropolitan University. IR spectra were recorded as

KBr discs in the range 4000–300 cm^À1on

a Perkin–Elmer

System 2000 Fourier transform spectrometer. ¹H, ¹³C and ¹⁹F NMR

spectra were recorded on a Bruker AVANCE 300 MHz spectrometer

with d(H) and d(C) referenced to external tetramethylsilane and

d(F) referenced to external trichlorofluoromethane. ¹²³Te and ¹²⁵Te

NMR spectra were recorded on a Jeol GSX 270 MHz spectrometer

with d(Te) referenced to Me₂Te, with a secondary reference for

d(Te) to diphenyl ditelluride (d(Te)=428 ppm). J(¹²⁵Te, ¹²⁵Te) values

are obtained by multiplying the experimentally obtained J(¹²³Te,

¹²⁵Te) values by 1.206, the ratio of the gyromagnetic ratios for ¹²⁵Te

(À8.51ꢃ107 rad T-1 S-1)^[3]and ¹²³Te (À7.06ꢃ107 rad T-1 S-1).^[3]As-

Figure 11. Plot of optimized (ZORA-SO/BP//B3LYP) vs. observed (solution-

state NMR spectra) J(¹²⁵Te,¹²⁵Te) SSCCs. : AB; : CCt; x: av.[a] All spectra run

in CDCl₃; d (ppm), J (Hz).

*

1

signments of ¹³C and H NMR spectra were made with the help of

H-H COSY and HSQC experiments. All measurements were per-

formed at 258C. All values reported for NMR spectroscopy are in

parts per million (ppm). Coupling constants (J) are given in Hertz

(Hz). Mass spectrometry was performed by the University of St An-

drews Mass Spectrometry Service. Electrospray Mass Spectrometry

(ESMS) was carried out on a Micromass LCT orthogonal accelerator

time of flight mass spectrometer. 1,8-diiodonaphthalene^[23]and 5,6-

dibromoacenaphthene^[24]were prepared following standard litera-

ture procedures.

5,6-diyl Ay; Y=Ph 1; Fp 2; Tol 3; An-p 4; An-o 5; Tp 6; Mes 7;

Tip 8).

In the solid, all compounds adopt AB or CCt conformations,

with larger mesityl and triisopropyl derivatives invariably fa-

vouring the CCt variant. The one anomaly in the series is A8

which adopts a BCc arrangement, but DFT calculations confirm

this optimizes to a CCt conformation and thus the structure

observed is likely to result from intermolecular interactions or

packing forces.

Diaryl ditellurides: (ArTeTeAr)

Exceptionally large through-space J(¹²⁵Te,¹²⁵Te) spin–spin

couplings (3289–3848 Hz) are observed experimentally for de-

rivatives substituted with bulky mesityl and triisopropyl

groups, consistent with the structure found in the solid and in-

dicating these species are permanently locked in a CCt-type

conformation. This is supported by DFT calculations with the

computed trend fitting well to the experimentally obtained J

values and a single minima found for each compound (CCt).

In contrast, compounds substituted by smaller Te(aryl)

groups display much lower J values (2050–2676 Hz), which

suggests in solution these species are rather fluxional and ex-

plore a significant region in phase space extending toward AB

conformers with their lower couplings. Computed J values for

naphthalenes N1, N3 and N4 are significantly overestimated,

whilst the observed couplings for the remaining set of com-

pounds, for which both AB and CCt minima are found, are

“bracketed” by the values computed for CCt (too high) and AB

(too low). This is consistent with previous findings that an

equilibrium must exist between AB and CCt conformers in so-

lution due to the small difference in their potential ener-

gies.^[10,11]

Diphenyl ditelluride was obtained from commercial sources and

used as received. Bis(4-methylphenyl) ditelluride (TolTeTeTol), bis(4-

methoxyphenyl) ditelluride (An-pTeTeAn-p), bis(2-methoxyphenyl)

ditelluride (An-oTeTeAn-o), bis(4-tertbutylphenyl) ditelluride (TpTe-

TeTp), bis(2,4,6-trimethylphenyl) ditelluride (MesTeTeMes) and

bis(2,4,6-triisopropanylphenyl) ditelluride (TipTeTeTip) were synthes-

ised from the respective aryl bromides following the procedure

outlined by Ando and co-workers.^[14]

PhTeTePh: ¹²⁵Te NMR (85.2 MHz, CDCl₃, 258C, PhTeTePh): d=

427.6 ppm (s); ¹²³Te NMR (70.7 MHz, CDCl₃, 258C, PhTeTePh): d=

1

434.1 ppm (s, J(¹²³Te,¹²⁵Te) =268 Hz).

TolTeTeTol: ¹²⁵Te NMR (85.2 MHz, CDCl₃, 258C, PhTeTePh): d=

432.8 ppm (s); ¹²³Te NMR (70.7 MHz, CDCl₃, 258C, PhTeTePh): d=

1

432.3 ppm (s, J(¹²³Te,¹²⁵Te) =787 Hz).

An-pTeTeAn-p: ¹²⁵Te NMR (85.2 MHz, CDCl₃, 258C, PhTeTePh): d=

461.3 ppm (s); ¹²³Te NMR (70.7 MHz, CDCl₃, 258C, PhTeTePh): d=

1

461.0 ppm (s, J(¹²³Te,¹²⁵Te) =216 Hz).

An-oTeTeAn-o: ¹²⁵Te NMR (85.2 MHz, CDCl₃, 258C, PhTeTePh): d=

175.9 ppm (s); ¹²³Te NMR (70.7 MHz, CDCl₃, 258C, PhTeTePh): d=

1

175.9 ppm (s, J(¹²³Te,¹²⁵Te) =279 Hz).

TpTeTeTp: ¹²⁵Te NMR (85.2 MHz, CDCl₃, 258C, PhTeTePh): d=

408.9 ppm (s); ¹²³Te NMR (70.7 MHz, CDCl₃, 258C, PhTeTePh): d=

1

409.9 ppm (s, J(¹²³Te,¹²⁵Te) =198 Hz).

Through-space spin–spin coupling can thus act not only as

a sensitive probe for investigating the underlying bonding sit-

uation between two interacting NMR spectroscopic active

nuclei, but can also be used as a tool for determining molecu-

FpTeTeFp: ¹²⁵Te NMR (85.2 MHz, CDCl₃, 258C, PhTeTePh): d=

463.1 ppm (s); ¹²³Te NMR (70.7 MHz, CDCl₃, 258C, PhTeTePh): d=

1

463.9 ppm (s, J(¹²³Te,¹²⁵Te) =129 Hz).

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MesTeTeMes: ¹²⁵Te NMR (85.2 MHz, CDCl₃, 258C, PhTeTePh): d=

201.6(s); ¹²³Te NMR (70.7 MHz, CDCl₃, 258C, PhTeTePh): d=

201.6 ppm (s, ¹J(¹²³Te,¹²⁵Te) =532 Hz).

to afford the purified target compound as a brown solid. An ana-

lytically pure sample was obtained from recrystallisation by diffu-

sion of hexane into a saturated solution of the compound in di-

chloromethane (0.67 g, 45%). M.p. 137–1398C; ¹H NMR (300 MHz,

TipTeTeTip: ¹²⁵Te NMR (85.2 MHz, CDCl₃, 258C, PhTeTePh): d=

3

4

183.2 ppm (s); ¹²³Te NMR (70.7 MHz, CDCl₃, 258C, PhTeTePh): d=

CDCl₃, 258C, Me₄Si): d=7.94 (dd, J(H,H)=7.2, J(H,H)=1.2 Hz, 2H;

3

4

1

182.6 ppm (s, J(¹²³Te,¹²⁵Te) =650 Hz).

Nap 4,5-H), 7.60 (dd, J(H,H)=8.2, J(H,H)=1.1 Hz, 2H; Nap 2,7-H),

7.55 (d, ³J(H,H)=8.8 Hz, 4H: TeAn-p 11,13,18,20-H), 7.06 (dd,

³J(H,H)=8.0,7.2 Hz, 2H; Nap 3,6-H), 6.67 (d, ³J(H,H)=8.8 Hz, 4H;

TeAn-p 10,14,17,21-H), 3.69 ppm (s, 6H; 2ꢃTeAn-p OCH₃); ¹²⁵Te NMR

(85.2 MHz, CDCl₃, 258C, PhTeTePh): d=601.9 ppm (s); ¹²³Te NMR

1,8-Bis(4-fluorophenyltelluro)naphthalene [Nap(TeFp)₂] (N2)

A solution of n-butyllithium in hexane (2.5m, 2.3 mL, 5.83 mmol)

4

(70.7 MHz, CDCl₃, 258C, PhTeTePh): d=601.8 ppm (s, J(¹²³Te,¹²⁵Te) =

was added dropwise to

a solution of 1,8-diiodonaphthalene

2189 Hz); MS (ES⁺): m/z (%): 626.97 (40) [M+OMe⁺], 612.96 (100)

[M+OH⁺]; elemental analysis calcd (%) for C₂₄H₂₀O₂Te₂: C 48.4, H

3.4; found: C 48.3, H 3.5.

(1.09 g, 2.87 mmol) in diethyl ether (50 mL) at À788C was added.

The mixture was stirred at this temperature for 1 h after which a so-

lution of bis(4-fluorophenyl) ditelluride (FpTeTeFp) (2.56 g,

5.74 mmol) in diethyl ether (200 mL) was added dropwise to the

mixture. The resulting mixture was stirred at À788C for a further

2 h. The reaction mixture was washed with 0.1m sodium hydroxide

(2ꢃ200 mL). The organic layer was dried with magnesium sulfate,

concentrated under reduced pressure, and purified by column

chromatography on silica gel (hexane) to give the title compound

as a brown solid. An analytically pure sample was obtained from

recrystallisation by diffusion of hexane into a saturated solution of

the compound in dichloromethane (1.07 g, 65%). M.p. 98–1008C;

¹H NMR (300 MHz, CDCl₃, 258C, Me₄Si): d=7.88 (dd, ³J(H,H)=

7.2 Hz, ⁴J(H,H)=1.2 Hz, 2H; Nap 4,5-H), 7.54 (dd, ³J(H,H)=8.2,

⁴J(H,H)=1.1 Hz, 2H; Nap 2,7-H), 7.49–7.39 (m, 4H; TeFp

1,8-Bis(2-methoxyphenyltelluro)naphthalene [Nap(TeAn-o)₂]

(N5)

1,8-Bis(2-methoxyphenyltelluro)naphthalene [Nap(TeAn-o)₂] (N5)

was prepared following the procedure described previously for N2,

with 1,8-diiodonaphthalene (0.81 g, 2.12 mmol), a solution of n-bu-

tyllithium in hexane (2.5m, 1.7 mL, 4.31 mmol) and (An-oTeTeAn-o)

(2.01 g, 4.24 mmol). The crude product was purified by column

chromatography on silica gel (hexane) to give the title compound

as a brown solid. An analytically pure sample was obtained from

recrystallisation by diffusion of hexane into a saturated solution of

the compound in dichloromethane (0.19 g, 15%). M.p. 58–608C;

¹H NMR (300 MHz, CDCl₃, 258C, Me₄Si): d=8.02 (dd, ³J(H,H)=7.1,

⁴J(H,H)=1.2 Hz, 2H; Nap 4,5-H), 7.71 (dd, ³J(H,H)=8.2, ⁴J(H,H)=

1.1 Hz, 2H; Nap 2,7-H), 7.18–7.04 (m, 4H; TeAn-o 13,19-H, Nap 3,6-

H), 6.78–6.67 (m, 4H; TeAn-o 11,14,17,20-H), 6.61–6.53 (m, 2H,

TeAn-o 12,18-H), 3.68 ppm (s, 6H; 2xTeAn-o OCH₃); ¹²⁵Te NMR

(85.2 MHz, CDCl₃, 258C, PhTeTePh): d=514.6 ppm (s); ¹²³Te NMR

3

10,14,16,20-H), 7.00 (dd, J(H,H)=8.0,7.2 Hz, 2H; Nap 3,6-H), 6.75–

6.65 ppm (m, 4H; TeFp 11,13,17,19-H); ¹⁹F NMR (282.3 MHz, CDCl₃,

258C, CCl₃F): d=À113.1 ppm (s); ¹²⁵Te NMR (85.2 MHz, CDCl₃, 258C,

PhTeTePh): d=615.8 ppm (s); ¹²³Te NMR (70.7 MHz, CDCl₃, 258C,

4

PhTeTePh): d=616.1 ppm (s, J(¹²³Te,¹²⁵Te) =2082 Hz); MS (ES⁺): m/z

(%): 602.93 (100) [M+OMe⁺]; elemental analysis calcd (%) for

C₂₂H₁₄F₂Te₂: C 46.2, H 2.5; found: C 46.4, H 2.3.

1,8-Bis(4-methylphenyltelluro)naphthalene [Nap(TeTol)₂]

(N3)

4

(70.7 MHz, CDCl₃, 258C, PhTeTePh): d=514.0 ppm (s, J(¹²³Te,¹²⁵Te) =

2219 Hz); MS (ES⁺): m/z (%): 626.99 (100) [M+OMe⁺]; elemental

analysis calcd (%) for C₂₄H₂₀O₂Te₂: C 48.4, H 3.4; found: C 48.5, H

3.3.

1,8-Bis(4-methylphenyltelluro)naphthalene [Nap(TeTol)₂] (N3) was

prepared by following the procedure described previously for N2

with 1,8-diiodonaphthalene (0.99 g, 2.63 mmol), a solution of n-bu-

tyllithium in hexane (2.5m, 2.1 mL, 5.34 mmol) and (TolTeTeTol)

(2.32 g, 5.26 mmol). The crude product was triturated with hexane

to afford the target compound as a brown solid. An analytically

pure sample was obtained from recrystallisation by diffusion of

hexane into a saturated solution of the compound in dichlorome-

1,8-Bis(4-tert-butylphenyltelluro)naphthalene [Nap(TeTp)₂]

(N6)

1

1,8-Bis(4-tert-butylphenyltelluro)naphthalene [Nap(TeTp)₂] (N6) was

prepared by following the procedure described previously for N2,

with 1,8-diiodonaphthalene (1.10 g, 2.90 mmol), a solution of n-bu-

tyllithium in hexane (2.5m, 2.4 mL, 5.90 mmol) and (TpTeTeTp)

(3.03 g, 5.81 mmol). The crude product was purified by column

chromatography on silica gel (hexane) to give the title compound

as a brown solid. An analytically pure sample was obtained from

recrystallisation by diffusion of hexane into a saturated solution of

the compound in CDCl₃(0.96 g, 51%). M.p. 72–748C; ¹H NMR

thane (0.19 g, 13%). M.p. 160–1628C (decomp); H NMR (300 MHz,

3

4

CDCl₃, 258C, Me₄Si): d=8.08 (dd, J(H,H)=7.2, J(H,H)=1.2 Hz, 2H;

3

4

Nap 4,5-H), 7.74 (dd, J(H,H)=8.2, J(H,H)=1.1 Hz, 2H; Nap 2,7-H),

3

7.56 (d, J(H,H)=8.2 Hz, 4H; TeTol 11,13,18,20-H), 7.19 (dd, J(H,H)=

8.0,7.2 Hz, 2H; Nap 3,6-H), 7.04 (d, ³J(H,H)=7.6 Hz, 4H; TeTol

10,14,17,21-H), 2.34 ppm (s, 6H; 2xTeTol p-CH₃); ¹²⁵Te NMR

(85.2 MHz, CDCl₃, 258C, PhTeTePh): d=607.6 ppm (s); ¹²³Te NMR

4

(70.7 MHz, CDCl₃, 258C, PhTeTePh): d=607.4 ppm (s, J(¹²³Te,¹²⁵Te) =

2145 Hz); MS (ES⁺): m/z (%): 594.98 (100) [M+OMe⁺]; elemental

3

4

analysis calcd (%) for C₂₄H₂₀Te₂: C 51.1, H 3.6; found: C 50.9, H 3.5.

(300 MHz, CDCl₃, 258C, Me₄Si): d=8.23 (dd, J(H,H)=7.2, J(H,H)=

1.2 Hz, 2H; Nap 4,5-H), 7.79 (dd, ³J(H,H)=8.2 Hz, ⁴J(H,H)=1.1 Hz,

2H; Nap 2,7-H), 7.69 (d, ³J(H,H)=8.4 Hz, 4H; TeTp11,13,21,23-H),

1,8-Bis(4-methoxyphenyltelluro)naphthalene [Nap(TeAn-p)₂]

3

7.33 (d, J(H,H)=8.4 Hz, 4H; TeTp 10,14,20,24-H), 7.24 (dd, J(H,H)=

8.0,7.2 Hz, 2H; Nap 3,6-H), 1.41 ppm (s, 18H; 2ꢃTeTp p-tBu);

¹²⁵Te NMR (85.2 MHz, CDCl₃, 258C, PhTeTePh): d=603.8 ppm (s);

¹²³Te NMR (70.7 MHz, CDCl₃, 258C, PhTeTePh): d=604.9 ppm (s,

⁴J(¹²³Te,¹²⁵Te) =2097 Hz); MS (ES⁺): m/z (%): 678.50 (100) [M+OMe⁺

]; elemental analysis calcd (%) for C₃₀H₃₂Te₂: C 55.6, H 5.0; found: C

55.7, H 4.9.

(N4)

1,8-Bis(4-methoxyphenyltelluro)naphthalene [Nap(TeAn-p)₂] (N4)

was prepared following the procedure described previously for N2,

with 1,8-diiodonaphthalene (0.95 g, 2.50 mmol), 2.5m solution of

n-butyllithium in hexane (2.0 mL, 5.10 mmol) and (An-pTeTeAn-p)

(2.37 g, 5.00 mmol). The crude product was triturated with hexane

Chem. Eur. J. 2015, 21, 3613 – 3627

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Full Paper

of hexane into a saturated solution of the compound in dichloro-

1,8-Bis(2,4,6-trimethylphenyltelluro)naphthalene

[Nap(TeMes)₂] (N7)

1

methane (1.21 g, 54%). M.p. 140–1428C; H NMR (300 MHz, CDCl₃,

3

258C, Me₄Si): d=7.73 (d, J(H,H)=7.2 Hz, 2H; Acenap 4,7-H), 7.60–

7.50 (m, 4H; TeFb 12,16,18,22-H), 6.94 (d, ³J(H,H)=7.2 Hz, 2H;

Acenap 3,8-H), 6.85–6.74 (m, 4H; TeFb 13,15,19,21-H), 3.22 ppm (s,

4H, 2ꢃCH₂); ¹⁹F NMR (282.3 MHz, CDCl₃, 258C, CCl₃F): d=

À113.6 ppm (s); ¹²⁵Te NMR (85.2 MHz, CDCl₃, 258C, PhTeTePh): d=

581.7 ppm (s); ¹²³Te NMR (70.7 MHz, CDCl₃, 258C, PhTeTePh): d=

579.9 ppm (s, ⁴J(¹²³Te,¹²⁵Te) =1746 Hz); MS (ES⁺): m/z (%): 628.95

(100) [M+OMe⁺]; elemental analysis calcd (%) for C₂₄H₁₆F₂Te₂: C

48.2, H 2.7; found: C 48.3, H 2.6.

1,8-Bis(2,4,6-trimethylphenyltelluro)naphthalene [Nap(TeMes)₂] (N7)

was prepared following the procedure described previously for N2,

with 1,8-diiodonaphthalene (0.92 g, 2.41 mmol), a solution of n-bu-

tyllithium in hexane (2.5m, 2.0 mL, 4.89 mmol) and (MesTeTeMes)

(2.40 g, 4.82 mmol). The crude product was purified by column

chromatography on silica gel (hexane) to give a yellow solid. An

analytically pure sample was obtained from recrystallisation by dif-

fusion of hexane into a saturated solution of the compound in di-

chloromethane (0.17 g, 11%). M.p. 188–1908C; ¹H NMR (300 MHz,

3

4

CDCl₃, 258C, Me₄Si): d=7.57 (dd, J(H,H)=7.2, J(H,H)=1.2 Hz, 2H;

5,6-Bis(4-methylphenyltelluro)acenaphthene [Acenap(Te-

Tol)₂] (A3)

3

4

Nap 4,5-H), 7.51 (dd, J(H,H)=8.2, J(H,H)=1.1 Hz, 2H; Nap 2,7-H),

6.92 (m, 2H; Nap 3,6-H), 6.82 (s, 4H; TeMes 11,13,20,22-H), 2.27 (s,

12H, 4ꢃTeMes o-CH₃), 2.18 ppm (s, 6H; 2ꢃTeMes p-CH₃); ¹²⁵Te NMR

(85.2 MHz, CDCl₃, 258C, PhTeTePh): d=397.4 ppm (s); ¹²³Te NMR

5,6-Bis(4-methylphenyltelluro)acenaphthene [Acenap(TeTol)₂] (A3)

was prepared following the procedure described previously for A2,

with 5,6-dibromoacenaphthene (0.36 g, 1.14 mmol), TMEDA

(0.5 mL, 3.03 mmol), a solution of n-butyllithium (2.5m) in hexane

(1.1 mL, 2.74 mmol) and (TolTeTeTol) (1.01 g, 2.28 mmol). The crude

product was washed with hexane affording a yellow solid which

was collected by filtration. An analytically pure sample was ob-

tained from recrystallisation by diffusion of hexane into a saturated

solution of the compound in dichloromethane (0.26 g, 38%). M.p.

155–1578C; ¹H NMR (300 MHz, CDCl₃, 258C, Me₄Si): d=7.78 (d,

³J(H,H)=7.2 Hz, 2H; Acenap 4,7-H), 7.55–7.46 (m, 4H; TeTol

12,16,18,22-H), 6.98–6.89 (m, 6H; Acenap 3,8-H, TeTol 13,15,19,21-

H), 3.23 (s, 4H; 2ꢃCH₂), 2.23 ppm (s, 6H; 2ꢃCH₃); ¹²⁵Te NMR

(85.2 MHz, CDCl₃, 258C, PhTeTePh): d=574.4 ppm (s); ¹²³Te NMR

4

(70.7 MHz, CDCl₃, 258C, PhTeTePh): d=396.7 ppm (s, J(¹²³Te,¹²⁵Te) =

3191 Hz); MS (ES⁺): m/z (%): 651.05 (100) [M+OMe⁺]; elemental

analysis calcd (%) for C₂₈H₂₈Te₂: C 54.3, H 4.6; found: C 54.3, H 4.7.

1,8-Bis(2,4,6-triisopropanylphenyltelluro)naphthalene [Nap(-

TeTip)₂] (N8)

1,8-Bis(2,4,6-triisopropanylphenyltelluro)naphthalene [Nap(TeTip)₂]

(N8) was prepared following the procedure described previously

for N2, with 1,8-diiodonaphthalene (0.98 g, 2.58 mmol), a solution

of n-butyllithium in hexane (2.5m, 2.1 mL, 5.24 mmol) and (TipTeTe-

Tip) (3.41 g, 5.16 mmol). The crude product was purified by column

chromatography on silica gel (hexane) to give the title compound

as a yellow oil (0.53 g, 26%). M.p. 48–508C; ¹H NMR (300 MHz,

4

(70.7 MHz, CDCl₃, 258C, PhTeTePh): d=574.1 ppm (s, J(¹²³Te,¹²⁵Te) =

1781 Hz); MS (ES⁺): m/z (%): 606.98 (100) [M+OH⁺]; elemental

3

4

CDCl₃, 258C, Me₄Si): d=7.91 (dd, J(H,H)=7.2, J(H,H)=1.0 Hz, 2H;

analysis calcd (%) for C₂₆H₂₂Te₂: C 53.0, H 3.8; found: C 52.7, H 3.8.

3

4

Nap 4,5-H), 7.75 (dd, J(H,H)=8.1, J(H,H)=1.0 Hz, 2H; Nap 2,7-H),

7.28 (s, 4H; TeTip 11,13,26,28,-H), 7.22–7.14 (m, 2H; Nap 3,6-H),

3.98 (septet, ³J(H,H)=6.8 Hz, 4H; TeTip o-CHMe₂), 3.13 (septet,

5,6-Bis(4-methoxyphenyltelluro)acenaphthene

[Acenap(TeAn-p)₂] (A4)

3

³J(H,H)=6.9 Hz, 2H; TeTip p-CHMe₂), 1.49 (d, J(H,H)=6.9 Hz, 12H;

3

TeTip p-CHMe₂), 1.29 ppm (d, J(H,H)=6.8 Hz, 24H; TeTip o-CHMe₂);

5,6-Bis(4-methoxyphenyltelluro)acenaphthene

[Acenap(TeAn-p)₂]

¹²⁵Te NMR (85.2 MHz, CDCl₃, 258C, PhTeTePh): d=346.4 ppm (s);

¹²³Te NMR (70.7 MHz, CDCl₃, 258C, PhTeTePh): d=346.1 ppm (s,

⁴J(¹²³Te,¹²⁵Te) =3095 Hz); MS (ES⁺): m/z (%): 819.23 (100) [M+OMe⁺

], 805.22 (60) [M+OH⁺]; elemental analysis calcd (%) for C₄₀H₅₂Te₂:

C 61.0, H 6.65; found: C 60.8, H 6.7.

(A4) was prepared following the procedure described previously

for A2, with 5,6-dibromoacenaphthene (0.36 g, 1.16 mmol), TMEDA

(0.5 mL, 3.09 mmol), a solution of n-butyllithium (2.5m) in hexane

(1.1 mL, 2.79 mmol) and (An-pTeTeAn-p) (1.10 g, 2.33 mmol). The

crude product was washed with hexane affording a brown solid

which was collected by filtration. An analytically pure sample was

obtained from recrystallisation by diffusion of hexane into a saturat-

ed solution of the compound in dichloromethane (0.39 g, 53%).

5,6-Bis(4-fluorophenyltelluro)acenaphthene [Acenap(TeFp)₂]

(A2)

1

M.p. 140–1428C (decomp); H NMR (300 MHz, CDCl₃, 258C, Me₄Si):

3

A solution of 5,6-dibromoacenaphthene (1.17 g, 3.74 mmol) in di-

ethyl ether (40 mL) was cooled to À10–08C on an ice-ethanol bath

and to this was added a solution of tetramethylethylenediamine

(TMEDA) (1.7 mL, 9.92 mmol). The mixture was allowed to stir for

15 min before a solution of n-butyllithium (2.5m) in hexane

(3.6 mL, 8.97 mmol) was added dropwise over a period of 15 min.

During these operations, the temperature of the mixture was main-

tained at À10–08C. The mixture was stirred at this temperature for

a further 1 h, before being cooled to À788C. A solution of bis(4-flu-

orophenyl) ditelluride (FpTeTeFp) (3.33 g, 7.47 mmol) in diethyl

ether (150 mL) was then added dropwise and the resulting solu-

tion was stirred at À788C for a further 2 h. The mixture was al-

lowed to warm to room temperature and then washed with 0.1n

sodium hydroxide (2ꢃ60 mL). The organic layer was dried over

magnesium sulfate and concentrated under reduced pressure to

afford a red solid. The crude product was washed with hexane af-

fording a cream solid which was collected by filtration. An analyti-

cally pure sample was obtained from recrystallisation by diffusion

d=7.88 (d, J(H,H)=7.3 Hz, 2H; Acenap 4,7-H), 7.75–7.66 (m, 4H;

3

TeAn-p 12,16,18,22-H), 7.06 (d, J(H,H)=7.3 Hz, 2H; Acenap 3,8-H),

6.84–6.77 (m, 4H; TeAn-p 13,15,19,21-H), 3.82 (s, 6H, 2ꢃTeAn-p

OCH₃), 3.35 ppm (s, 4H, 2ꢃCH₂); ¹²⁵Te NMR (85.2 MHz, CDCl₃, 258C,

PhTeTePh): d=567.8 ppm (s); ¹²³Te NMR (70.7 MHz, CDCl₃, 258C,

4

PhTeTePh): d=567.8 ppm (s, J(¹²³Te,¹²⁵Te) =1835 Hz); MS (ES⁺): m/z

(%): 652.99 (72) [M+OMe⁺], 638.97 (100) [M+OH⁺]; elemental

analysis calcd (%) for C₂₆H₂₂O₂Te₂: C 50.2, H 3.6; found: C 50.0, H

3.6.

5,6-Bis(2-methoxyphenyltelluro)acenaphthene

[Acenap(TeAn-o)₂] (A5)

5,6-Bis(2-methoxyphenyltelluro)acenaphthene

[Acenap(TeAn-o)₂]

(A5) was prepared following the procedure described previously

for A2, with 5,6-dibromoacenaphthene (1.32 g, 4.24 mmol), TMEDA

(1.8 mL, 11.27 mmol), a solution of n-butyllithium (2.5m) in hexane

(4.1 mL, 10.19 mmol) and (An-oTeTeAn-o) (4.02 g, 8.48 mmol). The

Chem. Eur. J. 2015, 21, 3613 – 3627

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3624

ꢂ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper

crude product was washed with hexane affording a cream solid

which was collected by filtration. An analytically pure sample was

obtained from recrystallisation by diffusion of hexane into a saturat-

ed solution of the compound in dichloromethane (1.03 g, 39%).

M.p. 75–778C; ¹H NMR (300 MHz, CDCl₃, 258C, Me₄Si): d=7.94 (d,

³J(H,H)=7.2 Hz, 2H; Acenap 4,7-H), 7.31–7.20 (m, 2H; TeAn-o

15,22-H), 7.16–7.06 (m, 4H; TeAn-o 13,20-H, Acenap 3,8-H), 6.87

(dd, ³J(H,H)=8.2, ⁴J(H,H)=0.8 Hz, 2H; TeAn-o 16,23-H), 6.79–6.69

(m, 2H; TeAn-o 14,21-H), 3.86 (s, 6H; 2ꢃTeAn-o OCH₃), 3.42 ppm (s,

4H; 2ꢃCH₂); ¹²⁵Te NMR (85.2 MHz, CDCl₃, 258C, PhTeTePh): d=

482.4 ppm (s); ¹²³Te NMR (70.7 MHz, CDCl₃, 258C, PhTeTePh): d=

481.9 ppm (s, ⁴J(¹²³Te,¹²⁵Te) =1796 Hz); MS (ES⁺): m/z (%): 652.98

(100) [M+OMe⁺]; elemental analysis calcd (%) for C₂₆H₂₂O₂Te₂: C

50.2, H 3.6; found: C 50.0, H 3.6.

ously for A2, with 5,6-dibromoacenaphthene (1.13 g, 3.63 mmol),

TMEDA (1.5 mL, 9.55 mmol), a solution of n-butyllithium (2.5m) in

hexane (3.5 mL, 8.63 mmol) and (TipTeTeTip) (4.78 g, 7.23 mmol).

The crude product was purified by column chromatography on

silica gel (hexane) to give the title compound as a brown solid. An

analytically pure sample was recrystallised from hexane (1.60 g,

54%). M.p. 164–1668C (decomp); ¹H NMR (300 MHz, CDCl₃, 258C,

3

Me₄Si): d=7.69 (d, J(H,H)=7.3 Hz, 2H; Acenap 4,7-H), 7.27 (s, 4H;

TeTip 13,15,28,30-H), 7.07 (d, ³J(H,H)=7.3 Hz, 2H; Acenap 3,8-H),

4.02 (septet, ³J(H,H)=6.8 Hz, 4H; TeTip o-CHMe₂), 3.39 (s, 4H;

3

Acenap 2ꢃCH₂), 3.12 (septet, J(H,H)=6.9 Hz, 2H; TeTip p-CHMe₂),

1.49 (d, ³J(H,H)=6.9 Hz, 12H; TeTip p-CHMe₂), 1.31 ppm (d,

³J(H,H)=6.8 Hz, 24H; TeTip o-CHMe₂); ¹²⁵Te NMR (85.2 MHz, CDCl₃,

258C, PhTeTePh): d=316.0 ppm (s); ¹²³Te NMR (70.7 MHz, CDCl₃,

258C, PhTeTePh): d=315.8 ppm (s, ⁴J(¹²³Te,¹²⁵Te) =2727 Hz); MS

(ES⁺): m/z (%): 847.23 (100) [M+H₂OMe⁺], 831.23 (85) [M+OH⁺],

814.23 (20) [M⁺]; elemental analysis calcd (%) for C₄₂H₅₂Te₂: C 62.0,

H 6.7; found: C 62.0, H 6.4.

5,6-Bis(4-tert-butylphenyltelluro)acenaphthene

[Acenap(TeTp)₂] (A6)

5,6-Bis(4-tert-butylphenyltelluro)acenaphthene [Acenap(TeTp)₂] (A6)

was prepared following the procedure described previously for A2

with 5,6-dibromoacenaphthene (1.10 g, 3.53 mmol), TMEDA

(1.6 mL, 9.37 mmol), a solution of n-butyllithium (2.5m) in hexane

(3.4 mL, 8.48 mmol) and (TpTeTeTp) (3.68 g, 7.06 mmol). The crude

product was purified by column chromatography on silica gel

(hexane) to give the title compound as a brown solid. An analyti-

cally pure sample was recrystallised by diffusion of hexane into

a saturated solution of the compound in dichloromethane (1.56 g,

61%). M.p. 55–578C; ¹H NMR (300 MHz, CDCl₃, 258C, Me₄Si): d=

5,6-Bis(4-fluorophenyltelluro)acenaphthylene

[Acenapyl(TeFp)₂] (Ay2)

2,3-Dichloro-5,6-dicyano-1,4-benzoquinone

(DDQ)

(1.5 g,

6.65 mmol) was added in one batch to a stirred solution of 5,6-

bis(4-fluorophenyltelluro)acenaphthene (A2) (2.65 g, 4.43 mmol) in

benzene (200 mL) and the mixture heated under reflux for 24 h.

After cooling to room temperature, pentane (200 mL) was added

and the mixture was filtered. The filtrate was passed through

a short column of silica with a pentane eluent and concentrated

under reduced pressure to yield the title compound as an orange

solid. An analytically pure sample was obtained from recrystallisa-

tion by diffusion of hexane into a saturated solution of the com-

3

7.83 (d, J(H,H)=7.3 Hz, 2H; Acenap 4,7-H), 7.54 (d, J(H,H)=8.4 Hz,

4H; TeTp 13,15,23,25-H), 7.34 (d, ³J(H,H)=8.4 Hz, 4H; TeTp

3

12,16,22,26-H), 6.96 (d, J(H,H)=7.3 Hz, 2H; Acenap 3,8-H), 3.24 (s,

4H; 2ꢃCH₂), 1.21 ppm (s, 18H; 2ꢃp-tBu); ¹²⁵Te NMR (85.2 MHz,

CDCl₃, 258C, PhTeTePh): d=571.4 ppm (s); ¹²³Te NMR (70.7 MHz,

CDCl₃, 258C, PhTeTePh): d=571.6 ppm (s, ⁴J(¹²³Te,¹²⁵Te) =1766 Hz);

MS (ES⁺): m/z (%): 705.09 (100) [M+OMe⁺]; elemental analysis

calcd (%) for C₃₂H₃₄Te₂: C 57.0, H 5.1; found: C 56.8, H 5.0.

1

pound in dichloromethane (0.48 g, 18%). M.p. 150–1528C; H NMR

3

(300 MHz, CDCl₃, 258C, Me₄Si): d=7.71 (d, J(H,H)=7.2 Hz, 2H; Ace-

napyl 4,7-H), 7.62–7.57 (m, 4H; TeFp 12,16-H), 7.17 (d, ³J(H,H)=

7.2 Hz, 2H; Acenapyl 3,8-H), 6.86–6.79 (m, 6H; TeFp 13–15-H),

6.75 ppm (s, 2H, Acenapyl 2ꢃCH); ¹⁹F NMR (282.3 MHz, CDCl₃,

258C, CCl₃F): d=À112.9 ppm (s); ¹²⁵Te NMR (85.2 MHz, CDCl₃, 258C,

PhTeTePh): d=610.3 ppm (s); ¹²³Te NMR (70.7 MHz, CDCl₃, 258C,

5,6-Bis(2,4,6-trimethylphenyltelluro)acenaphthene

[Acenap(TeMes)₂] (A7)

5,6-Bis(2,4,6-trimethylphenyltelluro)acenaphthene [Acenap(TeMes)₂]

(A7) was prepared following the procedure described previously

for A2, with 5,6-dibromoacenaphthene (0.23 g, 0.96 mmol), TMEDA

(0.4 mL, 2.55 mmol), a solution of n-butyllithium in hexane (2.5m,

0.9 mL, 2.31 mmol) and (MesTeTeMes) (0.96 g, 1.92 mmol). The

crude product was washed with hexane affording a yellow crystal-

line solid that was collected by filtration. An analytically pure

sample was obtained from recrystallisation by diffusion of hexane

into a saturated solution of the compound in dichloromethane

4

PhTeTePh): d=610.1 ppm (s, J(¹²³Te,¹²⁵Te) =1700 Hz); MS (ES⁺): m/z

(%): 628.93 (100) [M+OMe⁺], 614.92 (93) [M+OH⁺]; elemental

analysis calcd (%) for C₂₄H₁₄F₂Te₂: C 48.4, H 2.4; found C 48.2, H 2.3.

5,6-Bis(4-methylphenyltelluro)acenaphthylene

[Acenapyl(TeTol)₂] (Ay3)

1

(0.14 g, 22%). M.p. 125–1278C (decomp). H NMR (300 MHz, CDCl₃,

5,6-Bis(4-methylphenyltelluro)acenaphthylene

[Acenapyl(TeTol)₂]

3

258C, Me₄Si): d=7.33 (d, J(H,H)=7.3 Hz, 2H; Acenap 4,7-H), 6.80

(Ay3) was prepared following the procedure described previously

for Ay2, with DDQ (0.32 g, 1.41 mmol) and [Acenap(TeTol)₂] A3

(0.56 g, 0.94 mmol), yielding a red solid, which was recrystallized

by evaporation of a dichloromethane solution of the product to

afford red crystals (0.13 g, 23%). M.p. 180–1828C; ¹H NMR

3

(s, 4H; TeMes 13,15,18,22-H), 6.75 (d, J(H,H)=7.3 Hz, 2H; Acenap

3,8-H), 3.12 (s, 4H, 2ꢃCH₂), 2.30 (s, 12H; 4ꢃCH₃), 2.15 ppm (s, 6H;

2ꢃCH₃); ¹²⁵Te NMR (85.2 MHz, CDCl₃, 258C, PhTeTePh): d=

363.3 ppm (s); ¹²³Te NMR (70.7 MHz, CDCl₃, 258C, PhTeTePh): d=

362.9 ppm (s, ⁴J(¹²³Te,¹²⁵Te) =2819 Hz); MS (ES⁺): m/z (%): 677.06

(100) [M+OMe⁺]; elemental analysis calcd (%) for C₃₀H₃₀Te₂: C 55.8,

H 4.7; found: C 55.6, H 4.6.

3

(300 MHz, CDCl₃, 258C, Me₄Si): d=7.79 (d, J(H,H)=7.2 Hz, 2H; Ace-

napyl 4,7-H), 7.59 (d, ³J(H,H)=8.0, 2H; TeTol 12,16-H), 7.22 (d,

³J(H,H)=7.2, 2H; Acenapyl 3,8-H), 7.00 (d, ³J(H,H)=7.6, 2H; TeTol

13,15-H), 6.78 (s, 2H; Acenapyl 2ꢃCH), 2.28 ppm (s, 6H; TeTol 2ꢃ

CH₃); ¹²⁵Te NMR (85.2 MHz, CDCl₃, 258C, PhTeTePh): d=605.7 ppm

(s); ¹²³Te NMR (70.7 MHz, CDCl₃, 258C, PhTeTePh): d=605.9 ppm (s,

⁴J(¹²³Te,¹²⁵Te) =1785 Hz); MS (ES⁺): m/z (%): 618.98 (100) [M+OMe⁺

]; elemental analysis calcd (%) for C₂₆H₂₀Te₂: C 53.1; H 3.4; found C

52.9, H 3.4.

5,6-Bis(2,4,6-triisopropanylphenyltelluro)acenaphthene

[Acenap(TeTip)₂] (A8)

5,6-Bis(2,4,6-triisopropanylphenyltelluro)acenaphthene [Acenap(Te-

Tip)₂] (A8) was prepared following the procedure described previ-

Chem. Eur. J. 2015, 21, 3613 – 3627

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ꢂ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper

product affording orange crystals (0.21 g, 14%). M.p. 75–778C;

5,6-Bis(4-methylphenyltelluro)acenaphthylene

[Acenapyl(TeAn-p)₂] (Ay4)

3

¹H NMR (300 MHz, CDCl₃, 258C, Me₄Si): d=7.58 (d, J(H,H)=7.3 Hz,

3

2H; Acenapyl 4,7-H), 7.32 (d, J(H,H)=7.3 Hz, 2H; Acenapyl 3,8-H),

5,6-Bis(4-methylphenyltelluro)acenaphthylene [Acenapyl(TeAn-p)₂]

(Ay4) was prepared following the procedure described previously

for Ay2, with DDQ (0.32 g, 1.41 mmol) and [Acenap(TeAn-p)₂] A4

(0.56 g, 0.94 mmol), yielding a red solid, which was recrystallized

by evaporation of a dichloromethane solution of the product to

afford red crystals (0.13 g, 23%). M.p. 180–1828C; ¹H NMR

7.27 (s, 4H; TeTip 13,15,28,30-H), 6.92 (s, 2H; Acenapyl 9,10-H), 3.09

3

(septet, J(H,H)=6.7 Hz, 4H; TeTip o-CHMe₂), 3.92 (septet, J(H,H)=

3

6.9 Hz, 4H; TeTip p-CHMe₂), 1.45 (d, J(H,H)=6.9 Hz, 12H; TeTip p-

CHMe₂), 1.30 ppm (d, ³J(H,H)=6.8 Hz, 24H; TeTip o-CHMe₂);

¹²⁵Te NMR (85.2 MHz, CDCl₃, 258C, PhTeTePh): d=353.7 ppm (s);

¹²³Te NMR (70.7 MHz, CDCl₃, 258C, PhTeTePh): d=353.3 ppm (s,

⁴J(¹²³Te,¹²⁵Te) =2958 Hz); MS (ES⁺): m/z (%): 833.19 (100) [M+Na⁺];

elemental analysis calcd (%) for C₄₂H₅₂Te₂: C 62.1, H 6.45; found C

62.25, H 6.4.

3

(300 MHz, CDCl₃, 258C, Me₄Si): d=7.79 (d, J(H,H)=7.2 Hz, 2H; Ace-

napyl 4,7-H), 7.59 (d, ³J(H,H)=8.0, 2H; TeAn-p 12,16-H), 7.22 (d,

3

³J(H,H)=7.2, 2H; Acenapyl 3,8-H), 7.00 (d, J(H,H)=7.6, 2H; TeAn-p

13,15-H), 6.78 (s, 2H; Acenapyl 2xCH), 2.28 ppm (s, 6H; TeAn-p 2ꢃ

CH₃); ¹²⁵Te NMR (85.2 MHz, CDCl₃, 258C, PhTeTePh): d=605.7 ppm

(s); ¹²³Te NMR (70.7 MHz, CDCl₃, 258C, PhTeTePh): d=605.9 ppm (s,

⁴J(¹²³Te,¹²⁵Te) =1785 Hz); MS (ES⁺): m/z (%): 618.98 (100) [M+OMe⁺

]; elemental analysis calcd (%) for C₂₆H₂₀Te₂: C 53.1; H 3.4; found C

52.9, H 3.4.

Crystal structure analyses

X-ray crystal structures for N3, N4, N5, N7, A8, Ay2 and Ay8 were

determined at À148(1)8C using a Rigaku MM007 high-brilliance RA

generator (Mo Ka radiation, confocal optic) and Saturn CCD

system. At least a full hemisphere of data was collected using w

scans. Intensities were corrected for Lorentz, polarization, and ab-

sorption. Data for compounds N2, N6, A2, A6 and Ay6 were col-

lected at À100(1)8C and for A5, Ay3, Ay4 and Ay7 at À180(1)8C

using a Rigaku MM007 high-brilliance RA generator (Mo_Karadia-

tion, confocal optic) and Mercury CCD system. At least a full hemi-

sphere of data was collected using w scans. Data for A3 and A4

were determined at À148(1)8C with the St Andrews Robotic Dif-

fractometer,^[25]a Rigaku ACTOR-SM, and a Saturn 724 CCD area de-

tector with graphite-monochromated Mo_Karadiation (l=

0.71073 ꢁ). Data were corrected for Lorentz, polarisation and ab-

sorption. Data for all compounds analyzed were collected and pro-

cessed using CrystalClear (Rigaku).^[26]Structures were solved by

direct methods^[27]and expanded using Fourier techniques.^[28]Non-

hydrogen atoms were refined anisotropically. Hydrogen atoms

were refined using the riding model. All calculations were per-

formed using the CrystalStructure^[29]crystallographic software

package except for refinement, which was performed using

SHELXL2013.^[30]

5,6-Bis(4-tert-butylphenyltelluro)acenaphthylene [

Acenapyl(TeTp)₂] (Ay6)

5,6-Bis(4-tert-butylphenyltelluro)acenaphthylene [Acenapyl(TeTp)₂]

(Ay6) was prepared following the procedure described previously

for Ay2, with DDQ (1.06 g, 4.66 mmol) and [Acenap(TeTp₂] A6

(2.00 g, 2.97 mmol), yielding a red solid, which was recrystallized

by evaporation of a chloroform solution of the product to afford

red crystals (0.23 g, 12%). M.p. 187–1898C; ¹H NMR (300 MHz,

3

CDCl₃, 258C, Me₄Si): d=7.83 (d, J(H,H)=7.2 Hz, 2H; Acenapyl 4,7-

H), 7.61 (d, ³J(H,H)=8.3 Hz, 2H; TeTp 12,16-H), 7.24–7.18 (m, 4H;

Acenapyl 3,8-H, TeTp 13,15-H), 6.77 (s, 2H; Acenapyl 2ꢃCH),

1.22 ppm (s, 18H; TeTp 2ꢃp-tBu); ¹²⁵Te NMR (85.2 MHz, CDCl₃,

258C, PhTeTePh): d=600.5 ppm (s); ¹²³Te NMR (70.7 MHz, CDCl₃,

258C, PhTeTePh): d=600.7 ppm (s, ⁴J(¹²³Te,¹²⁵Te) =1772 Hz); MS

(ES⁺): m/z (%): 703.08 (100) [M+OMe⁺]; elemental analysis calcd

(%) for C₃₂H₃₂Te₂: C 57.2; H 4.8; found C 57.1, H 4.9.

5,6-Bis(2,4,6-trimethylphenyltelluro)acenaphthylene

[Acenapyl(TeMes)₂] (Ay7)

CCDC-1027368 (A2), -1027388 (A3), -1027390 (A4), 1027391 (A5),

1027393 (A6), -1027369 (A8), -1027371 (Ay2), -1027373 (Ay3),

-1027375 (Ay4), -1027377 (Ay6), -1027379 (Ay7), -1027381 (Ay8),

-1027383 (N2), -1027385 (N3), -1027396 (N4), 1027398 (N5),

-1027400 (N6), 1027402 (N7). 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.

5,6-Bis(2,4,6-trimethylphenyltelluro)acenaphthylene

[Acenapyl(-

TeMes)₂] (Ay7) was prepared following the procedure described

previously for Ay2, with DDQ (0.19 g, 0.83 mmol) and [Acenap(-

TeMes)₂] A7 (0.36 g, 0.55 mmol), to yield a red solid that was re-

crystallized by evaporation of a dichloromethane solution of the

product affording red crystals (0.03 g, 9%). M.p. 171–1738C

(decomp); ¹H NMR (300 MHz, CDCl₃, 258C, Me₄Si): d=7.31 (d,

³J(H,H)=7.3, 2H; Acenapyl 4,7-H), 7.06 (d, ³J(H,H)=7.2, 2H; Ace-

napyl 3,8-H), 6.90 (s, 2H; TeMes 13,15-H), 6.70 (s, 2H; 2ꢃCH), 2.42

(s, 6H; TeMes 2ꢃCH₃), 2.22 ppm (s, 3H; TeMes 1ꢃCH₃); ¹²⁵Te NMR

(85.2 MHz, CDCl₃, 258C, PhTeTePh): d=406.9 ppm (s); ¹²³Te NMR

Solid-state NMR spectroscopy

¹²⁵Te solid-state NMR spectroscopic experiments were performed

using a Bruker Avance III spectrometer operating at a magnetic

field strengths of either 9.4 or 14.1 T, corresponding to a ¹²⁵Te

Larmor frequency of 126.2 MHz. Experiments were carried out

using conventional 4- and 1.9 mm MAS probes, with MAS rates be-

tween 14 and 40 kHz. Chemical shifts are referenced relative to

(CH₃)₂Te at 0 ppm, using the isotropic resonance of solid Te(OH)₆

(site 1) at 692.2 ppm as a secondary reference. Transverse magneti-

4

(70.7 MHz, CDCl₃, 258C, PhTeTePh): d=406.3 ppm (s, J(¹²³Te,¹²⁵Te) =

2956 Hz); MS (ES⁺): m/z (%): 690.94 (100) [M+Na₂⁺], 674.96 (55)

[M+OMe⁺]; elemental analysis calcd (%) for C₃₀H₂₈Te₂: C 56.0, H

4.4; found C 55.9, H 4.5.

5,6-Bis(2,4,6-triisopropanylphenyltelluro)acenaphthylene

[Acenapyl(TeTip)₂] (Ay8)

1

zation was obtained by cross polarization (CP) from H using opti-

mized contact pulse durations of 8 ms, and two-pulse phase mod-

1

5,6-Bis(2,4,6-triisopropanylphenyltelluro)acenaphthylene

[Acena-

ulation (TPPM) H decoupling during acquisition. Spectra were ac-

pyl(TeTip)₂] (Ay8) was prepared following the procedure described

previously for Ay2, with DDQ (0.66 g, 2.91 mmol) and [Acenap(Te-

Tip)₂] A8 (1.56 g, 1.92 mmol), to yield an orange solid that was re-

crystallized by evaporation of a dichloromethane solution of the

quired with a recycle interval of 50 and 55 s. The position of the

isotropic resonances within the spinning sidebands patterns were

unambiguously determined by recording a second spectrum at

a higher MAS rate. A more detailed description of the experimental

Chem. Eur. J. 2015, 21, 3613 – 3627

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3626

ꢂ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper

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Computational details

The same levels were employed as in our recent study on peri-

naphthyl ditellurides,^[11]that is, geometry optimisations were car-

ried out at the B3LYP/6-31G* level (SDD pseudopotential with aug-

mented valence basis on Te), J values computed^[30]at the ZORA-

Spinorbit/BP86/TZ2P level (which has performed well for the com-

putation of SSCCs involving fourth-row and heavier elements).^[31]

See the Supporting Information for further details and references.

Acknowledgements

Elemental analyses were performed by Stephen Boyer at the

London Metropolitan University. Mass spectrometry was per-

formed by Caroline Horsburgh at the University of St. Andrews

Mass Spectrometry Service. The author(s) would like to ac-

knowledge the use of the EPSRC UK National Service for Com-

putational Chemistry Software (NSCCS) at Imperial College

London in carrying out this work. Calculations were performed

using the EaStCHEM Research Computing Facility maintained

by Dr. H. Frꢀchtl and a Silicon Graphics Altix cluster at NSCCS.

The work in this project was supported by the Engineering

and Physical Sciences Research Council (EPSRC). M.B. wishes to

thank EaStCHEM and the University of St Andrews for support.

Keywords: bis(tellurides) · conformational dependence · DFT

calculations · NMR spectroscopy · spin–spin coupling · X-ray

crystallography

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ˇ

[11] M. Bꢀhl, F. R. Knight, A. Krꢄstkovꢅ, I. Malkin Ondꢄk, O. L. Malkina, R. A. M.

Received: October 10, 2014

Randall, A. M. Z. Slawin, J. D. Woollins, Angew. Chem. 2013 , 125 , 2555;

Angew. Chem. Int. Ed. 2013 , 52 , 2495.

Published online on December 22, 2014

Chem. Eur. J. 2015, 21, 3613 – 3627

www.chemeurj.org

3627

ꢂ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Article Doi

Conformational dependence of through-space tellurium-tellurium spin-spin coupling in peri-substituted bis(tellurides)

DOI: 10.1002/chem.201405599

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Article abstract of DOI:10.1002/chem.201405599

Full text of DOI:10.1002/chem.201405599

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