Carbyne complexes of the group 6 metals containing 1,4,7-triazacyclononane and its 1,4,7-trimethyl derivative

DOI: 10.1016/S0022-328X(97)00578-0

Source and publish data:

Journal of Organometallic Chemistry p. 255 - 263 (1998)

Update date:2022-08-03

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Authors:

Lee, Fu-Wa

Chan, Michael Chi-Wang

Cheung, Kung-Kai

Che, Chi-Ming

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Article abstract of DOI:10.1016/S0022-328X(97)00578-0

Interaction of Cl(CO)₂py₂MCPh (M=Mo, W) with 1,4,7-trimethyl-1,4,7-triazacyclononane (Me₃TACN) in THF, followed by metathesis using NaBPh₄ in aqueous medium, readily afford [(Me₃TACN)M(CO)₂(CPh)]BPh₄ (M=Mo (1a), W (2)). [(TACN)Mo(CO)₂(CPh)]BPh₄ (1b) is similarly prepared using the molybdenum precursor and 1,4,7-triazacyclononane (TACN). Complex 1a, 1b and 2 are stable in the presence of concentrated hydrochloric acid at room temperature. The crystal structures of 1a and 2 both show that the three nitrogen atoms of Me₃TACN are not equidistant from the metal centre as a consequence of the different trans influences of the carbyne and carbonyl groups. Complexes 1a, 1b and 2 exhibit intense absorption bands at 320-340 nm and weak absorptions in the 400-500 nm region, while excitation of 2 at 330 nm in acetonitrile gives an emission at 630 nm with a lifetime of 83 ns (Φ_em=1.6×10^-4) at room temperature. The cyclic voltammograms of 1a and 2 in acetonitrile consist of a quasi-reversible couple (-2.15 V vs. Cp₂Fe^0/+) and an irreversible wave (+0.77 V vs. Cp₂Fe^0/+). Both couples are assigned to ligand-centred processes. Reaction of Me₃TACN with Cl(CO)₂py₂CrCPh in THF resulted in cleavage of the carbyne moiety to yield a binuclear product.

Full text of DOI:10.1016/S0022-328X(97)00578-0

Journal of Organometallic Chemistry 552 1998 255–263

Carbyne complexes of the group 6 metals containing

1,4,7-triazacyclononane and its 1,4,7-trimethyl derivative

)

Fu-Wa Lee, Michael Chi-Wang Chan, Kung-Kai Cheung, Chi-Ming Che

Department of Chemistry, The UniÕersity of Hong Kong, Pokfulam Road, Hong Kong, China

Received 21 July 1997

Abstract

Interaction of Cl CO ₂py₂M[CPh MsMo, W with 1,4,7-trimethyl-1,4,7-triazacyclononane Me₃TACN in THF, followed by

wŽ . Ž .x Ž ..

Ž .

metathesis using NaBPh₄in aqueous medium, readily afford Me₃TACN M CO [CPh BPh₄M s Mo 1a , 2 .

TACN Mo CO [CPh BPh₄1b is similarly prepared using the molybdenum precursor and 1,4,7-triazacyclononane TACN .

wŽ

. Ž

Complex 1a, 1b and 2 are stable in the presence of concentrated hydrochloric acid at room temperature. The crystal structures of 1a and 2

both show that the three nitrogen atoms of Me₃TACN are not equidistant from the metal centre as a consequence of the different trans

influences of the carbyne and carbonyl groups. Complexes 1a, 1b and 2 exhibit intense absorption bands at 320–340 nm and weak

absorptions in the 400–500 nm region, while excitation of 2 at 330 nm in acetonitrile gives an emission at 630 nm with a lifetime of 83 ns

F_ems1.6=10^yat room temperature. The cyclic voltammograms of 1a and 2 in acetonitrile consist of a quasi-reversible couple

0rq

. Both couples are assigned to ligand-centred processes.

y2.15 V vs. Cp₂Fe

and an irreversible wave q0.77 V vs. Cp₂Fe

Reaction of Me₃TACN with Cl CO ₂py₂Cr[CPh in THF resulted in cleavage of the carbyne moiety to yield a binuclear product. q 1998

Elsevier Science S.A.

Keywords: Carbyne complexes; Group 6 metals; Macrocyclic amine ligands; Photochemistry; Electrochemistry

1. Introduction

plexes are evidently more stable than their acyclic con-

geners 21 . Herein is described the products from the

Investigation into the carbyne chemistry of Group 6

metals has proliferated in the last decade 1,2 . Many

neutral carbyne complexes with facial monoanionic lig-

reaction of Cl CO py₂M[CPh MsCr, Mo, W with

the triamine ligands and their structural, photophysical

and electrochemical properties.

. Ž

.x Ž

ands of the type LM CO [CR MsMo, W; Rs

alkyl, aryl, ferrocenyl; LsCp, Cp⁾or indenyl 3–6 ,

)

Tp Tris pyrazolyl borate 7,8 , Tp Tris 3,5-dimeth-

w x w

Ž . 4₃x w

ylpyrazolyl borate 9 , C₅H₅Co P O R₂

10 have

2. Results and discussion

been studied. Amino and thio-stabilized derivatives have

Reaction of Me₃TACN or TACN with

Cl CO py₂Mo[CPh in THF, followed by metathesis

et al. have described the synthesis and structure of the

heteroatom-stabilized complex Tp W CPMe₂Ph

CO PF₆16 . The ability of the tridentate macrocy-

cles 1,4,7-trim ethyl-1,4,7-triazacyclononane

Me₃TACN and 1,4,7-triazacyclononane TACN to

accommodate metal centres in high and low oxidation

states is well documented 17–20 . The resultant com-

with sodium tetraphenylborate, afford the yellow com-

. Ž

plexes Me₃TACN Mo CO [CPh BPh₄1a and

. Ž

TACN Mo CO [CPh BPh₄1b respectively. Sim-

ilarly, interaction of Me₃TACN with Cl CO

py₂W[CPh yields Me₃TACN W CO [CPh BPh₄

. Ž

Ž . Ž

Ä¹

Scheme 1 . The H and C H NMR data suggest

that complexes 1a, 1b and 2 contain a mirror plane

along the metal–carbyne bond which bisects the tri-

amine ligand and the two terminal carbonyl groups as

expected. The high carbyne carbon chemical shifts in

Corresponding author.

0022-328X

(

)

256

F.-W. Lee et al.rJournal of Organometallic Chemistry 552 1998 255–263

Scheme 1.

Ä¹

the C H NMR spectra of 1a, 1b and 2 show that

Complexes 1a, 1b and 2 showed no observable

changes after 3 months in aerobic dichloromethane,

acetonitrile, acetone or water. Indeed, they are stable in

the presence of concentrated HCl at ambient tempera-

ture for several hours. No reaction is observed upon

treatment of 1a or 2 with alkylating reagents such as

PhLi and MeLi or LiAlH₄in THF. Attempts to prepare

carbonyl-free carbyne complexes from 1a and 2 through

they are more electron-deficient than the terminal car-

bonyl carbons Table 1 .

The higher n CO values in the IR spectrum of 1a

compared to 2 are consistent with the greater electron

density associated with W at the same oxidation state.

Complex 2 exhibits lower carbonyl stretching energies

than other carbyne complexes of the respective metals

listed in Table 1. This implies that the electron-donating

strength of the ligands are in the order Me₃TACN)

TACN)TpGCp, and the metal centres of complexes

substitution in refluxing neat P OMe or by oxidation

using bromine failed.

Since no cationic carbyne complexes containing

purely s-donor facial ligands have been structurally

characterized, the X-ray crystal structures of 1a and 2

containing Me₃TACN are more nucleophilic 15 . A

comparison of n CO in Table 1 shows that the carbyne

moiety is a stronger p-acidic ligand than a terminal

carbonyl, but weaker than a nitrosyl group in

Me₃TACN Mo CO NO

W CO NO . We have therefore demonstrated that

have been determined Table 2 . The ORTEP plot of

. Ž

x^q

1a and the atomic

Me₃TACN Mo CO [CPh

. Ž

x^q

and

Me₃TACN

numbering scheme are shown in Fig. 1. Selected bond

distances and angles and atomic coordinates are col-

lected in Tables 3 and 4. The molybdenum centre is in a

distorted octahedral environment and is bonded to three

. Ž

x^q

carbyne complexes can be prepared using pure s-donor

facial ligands.

Table 1

Ä¹

Carbonyl stretching frequencies and selected

H NMR data for Group 6 complexes containing Me₃TACN, TACN and related ligands

.^aŽ

.Ž

.^dŽ

Complex

n CO cm

d M[C ppm

d M–CO ppm

References

wŽ

.Ž .

x^qŽ

Me₃TACN CO ₂Mo[CPh 1a

1980s, 1906s

1997s, 1914s

1975s, 1879s

1992s, 1922s^b

1986s, 1903s^c

1880vs, 1750s

1880vs, 1744s

2010vs, 1920s

1995vs, 1900s

298.0

294.3

288.0

299.3^e

284.8^f

225.2

225.8

224.6

221.3^e

224.9^f

.Ž

x^qŽ

TACN CO ₂Mo[CPh 1b

.Ž

x^qŽ .

Me₃TACN CO W[CPh

w x

Cp CO W[CPh

Tp CO W[CC₆H₄Me-4

wŽ

. x

Me₃TACN Mo CO

. x

Me₃TACN W CO

. Ž .x^q

Me₃TACN Mo CO NO

. Ž .x^q

Me₃TACN W CO NO

^aKBr unless specified otherwise.

^bIn n-hexane.

^cIn CH₂Cl₂.

^dIn d₆-acetone unless specified otherwise.

^eIn CD₂Cl₂.

^fIn CD₂Cl₂–CH₂Cl₂.

d M–CO not assigned.

(

)

F.-W. Lee et al.rJournal of Organometallic Chemistry 552 1998 255–263

257

Table 2

Crystal data for 1a and 2

2. Selected bond distances and atomic coordinates are

Ž . Ž .

listed in Tables 5 and 6 respectively. The W 1 –C 3

Ž .

Ž . Ž . Ž .

distance of 1.800 6 A and the W 1 –C 3 –C 4 angle

Ž .

w x

C₁₈H₂₆N₃O₂W

Formula

C₁₈H₂₆N₃O₂Mo

of 174.4 4 8 correspond to sp-hybridization at the C 3

carbon. In comparison with the carbyne bond distance

C₂₄H₂₀B

Formula

Crystal system

Space group

C₂₄H₂₀

Triclinic

Ž .

Ž . .

Triclinic

1 .8 2 2

a n d a n g le

1 7 6 2 8

Ž .

Pı No. 2

w x

Cp CO W[CC₆H₄Me-4 5 , it appears that the more

electron-donating Me₃TACN ligand has little structural

Ž .

a A

Ž .

13.216 2

13.204 2

Ž .

b A

14.331 4

Ž .

10.774 2

Ž .

96.56 2

110.21 1

98.41 2

14.315 2

Ž .

10.7754 9

Ž .

97.253 8

110.231 9

Ž .

98.54 1

impact upon the metal–carbyne interaction. The rela-

Ž .

c A

Ž . Ž .

Ž .

tively long W 1 –N 3 distance 2.316 5 A is again

Ž .

a 8

ascribed to the trans influence of the carbyne moiety.

Ž .

b 8

Treatment of Me₃TACN with Cl CO py₂Cr[CPh

Ž .

^IIIŽ

yields the binuclear species Me₃TACN Cr₂m-

Ž .

V A

1864.2 8

731.60

1.303

3.90

764

301

442

0.042, 0.051

1854.9 4

819.51

1.467

32.17

828

301

442

0.031, 0.037

.Ž

Ž .

3 as the major product

OH m-O₂CCH₂Ph PF₆

Scheme 1 . The precise mechanism for its formation is

M_r

d_cg cm

unclear, although coupling of the carbyne and carbonyl

ligands is apparently involved. Formation of new car-

bon–carbon bond by intramolecular carbonyl–carbyne

. Ž

m Mo–K a cm

F 000

Ž .

T K

coupling is rare in chromium chemistry 26 . The trans-

formation also entails reduction of the metal centre, and

in the absence of a reducing agent, the change in

Refined parameters

R, wR

oxidation state may be the result of Cr IV dispropor-

x²

tionation 27 . Isolation of the dinuclear complex

Me₃TACN nitrogen atoms, two terminal carbonyl lig-

Ž .

^IIIŽ

.Ž

₂x

Me₃TACN Cr₂m-OH m-O₂CMe

has been

ands and one phenyl carbyne moiety. The Mo–C 3 –

Ž . Ž . . Ž .

reported 28 . A minor product isolated in 2% yield

displays carbonyl stretching bands at 1980 and 1901

cm^y1in the IR spectrum and a molecular cluster at

mrz 368 in the mass spectrum. These data correspond

C 4 angle 174.7 5 8 and short Mo–C 3 bond

Ž .

1.797 6

are comparable to those in

. w x

Ž .

Regarding the Mo–N TACN distances, the signifi-

Ž . Ž .

Br CO py₂Mo[CPh 165.5 5 8 and 1.799 4 A 24 .

. Ž

x^q

to the desired Me₃TACN Cr CO [CPh frag-

cantly longer Mo 1 –N 3 bond is attributed to the

ment, but further characterisation was precluded due to

its unstable nature.

greater trans influence of the carbyne group 25 . The

short Mo 1 –N 1 and Mo 1 –N 2 bonds are consis-

tent with the high degree of back-bonding and relatively

Ž . Ž .

The molecular structure of 3 has been determined,

although the quality of data is poor Section 4 . The

Ž . Ž .

low n CO values in 1a. The long Mo 1 -N 3 bond

chromium atoms are linked by two PhCH₂CO₂groups

and one OH bridge while each metal centre is in a

distorted octahedral environment and bonded to three

also explains the deshielded C_carbynechemical shift in

Ä¹

the C H NMR spectrum.

wŽ

. Ž

x^q

2 and the atomic numbering scheme are shown in Fig.

The ORTEP plot of Me₃TACN W CO [CPh

Ž .

nitrogen atoms of Me₃TACN. The PhCH₂CO₂and

OH bridging modes are similar to those in the related

Table 3

Selected bond lengths A and angles 8 for 1a

Ž . Ž . Ž .

Ž .

Mo 1 –C 1 1.997 7

Ž . Ž .

Ž .

Mo 1 –C 2 1.976 7

Ž . Ž .

Ž .

Mo 1 –C 3 1.797 6

Ž . Ž .

Ž .

Mo 1 –N 1 2.276 4

Ž . Ž .

Ž .

Mo 1 –N 2 2.280 4

Ž . Ž .

Ž .

Mo 1 –N 3 2.351 4

Ž . Ž .

Ž .

C 3 –C 4 1.459 7

Ž . Ž .

Ž .

C 1 –O 1 1.146 7

Ž . Ž .

Ž .

C 2 –O 2 1.151 7

Ž . Ž . Ž .

Ž .

Mo 1 –C 3 –C 4 174.7 5

Ž . Ž . Ž .

Ž .

Mo 1 –C 1 –O 1 176.2 6

Ž . Ž . Ž .

Ž .

Mo 1 –C 2 –O 2 175.8 6

Ž . Ž . Ž . Ž .

N 1 –Mo 1 –C 1 169.1 2

Ž . Ž . Ž . Ž .

N 2 –Mo 1 –C 2 172.4 2

wŽ Ž

.x^q

Fig. 1. ORTEP plot of Me₃TACN Mo CO [CPh 40% proba-

. Ž

Ž . Ž . Ž . Ž .

N 3 –Mo 1 –C 3 177.2 2

bility ellipsoids .

(

)

258

F.-W. Lee et al.rJournal of Organometallic Chemistry 552 1998 255–263

Table 4

Atomic coordinates and B_isorB_eqfor 1a

Atom

Ž .

B_eq

Ž .

3.42 1

Mo 1

Ž .

0.26237 4

0.17040 4

y0.00209 5

Ž .

y0.1635 5

Ž .

7.4 2

O 1

0.3777 4

0.0578 4

Ž .

7.5 2

O 2

0.0891 4

y0.0215 4

y0.0902 5

Ž .

0.2435 3

Ž .

0.1488 5

Ž .

4.2 1

N 1

Ž .

0.2008 4

Ž .

3.9 1

N 2

0.3882 4

0.3107 3

0.0845 4

Ž .

3.7 1

N 3

0.3797 4

0.1424 3

0.2047 4

Ž .

4.8 2

C 1

0.3385 5

0.1016 5

y0.1037 6

Ž .

y0.0526 6

Ž .

4.6 2

C 2

Ž .

0.1534 5

0.0490 5

Ž .

3.9 1

C 3

0.1781 5

0.1916 4

y0.1632 6

Ž .

y0.2989 5

Ž .

3.2 1

C 4

0.1098 4

0.1999 4

Ž .

4.0 1

C 5

0.0925 5

0.1262 4

y0.4060 6

Ž .

y0.5343 6

Ž .

5.2 2

C 6

Ž .

0.0290 5

0.1346 5

Ž .

6.8 2

wŽ Ž

.x^q

Fig. 2. ORTEP plot of Me₃TACN W CO [CPh 30% proba-

. Ž

C 7

y0.0179 6

0.2139 7

y0.5570 7

Ž .

y0.0020 6

Ž .

y0.4532 8

Ž .

7.0 3

C 8

0.2865 6

bility ellipsoids .

Ž .

5.2 2

C 9

0.0614 6

0.2789 5

y0.3236 7

Ž .

0.0891 7

Ž .

5.9 2

C 10

0.0809 5

0.2428 5

Ž .

5.0 2

C 11

0.2626 5

0.3470 5

0.2006 6

Ž .

4.8 2

C 12

0.3221 5

0.3801 4

0.1132 6

Complexes 1a, 1b and 2 exhibit intense absorption

Ž .

5.9 2

C 13

0.4360 6

0.3443 5

y0.0136 7

Ž .

0.2109 6

Ž .

4.5 2

C 14

0.4809 5

0.3042 5

bands at 320–340 nm and weak absorptions in the

Ž .

4.5 2

C 15

0.4884 5

0.2012 5

0.2230 6

400–500 nm region Fig. 3 . The large extinction coef-

ficients observed for the high energy bands at 324, 336

and 328 nm for 1a, 1b and 2 respectively suggest that

Ž .

5.2 2

C 16

0.3883 5

0.0407 5

0.2022 6

Ž .

4.4 2

C 17

0.3409 5

0.1741 4

0.3148 6

Ž .

4.6 2

C 18

0.2220 5

0.1857 5

0.2575 6

they originate from charge transfer transitions 31 , pre-

sumably MLCT. With reference to previous studies by

Ž .

3.3 1

C 19

0.7794 4

0.3835 4

0.7207 5

Ž .

C 20

0.8815 5

0.4319 4

0.8155 6

4.2 1

Ž .

5.0 2

Ž .

C 21

0.9535 5

0.4979 5

0.7843 7

w x

Bocarsly et al. 32 , Schoch et al. 33 and Xue et al.

Ž .

5.3 2

Ž .

5.0 2

C 22

0.9274 5

Ž .

0.5186 5

Ž .

0.6576 8

Ž .

31 on Mo IV , W IV and Re V carbyne complexes,

C 23

0.8277 6

0.4719 5

0.5602 6

it is likely that the low energy absorptions at l)400

nm with low ´_maxare due to a d_{x y}™d_pd_{x z}, d _{y z}

Ž .

4.0 1

Ž .

3.0 1

Ž .

4.1 1

Ž .

4.8 2

Ž .

5.0 2

Ž .

4.6 2

C 24

0.7577 5

0.4050 4

0.5922 6

⁾Ž

Ž .

C 25

0.5667 4

0.3111 4

0.6865 5

Ž .

C 26

0.5316 5

Ž .

0.3915 4

Ž .

0.6401 6

Ž .

transition.

C 27

0.4214 5

0.4027 5

0.5985 6

Excitation of complex 2 at 330 nm in acetonitrile

Ž .

C 28

0.3425 5

0.3284 6

0.6021 6

gives an emission at 630 nm with a lifetime of 83 ns

Ž .

C 29

0.3735 5

0.2481 5

0.6450 6

Ž .

F_ems1.6=10

at room temperature Fig. 4 . The

Ž .

C 30

0.4826 5

Ž .

0.2387 4

Ž .

0.6880 5

Ž .

4.0 1

Ž .

3.4 1

large difference in emission and lowest allowed adsorp-

tion energies and the relatively long emission lifetime

suggest that the transitions involved are due to spin-for-

C 31

0.7166 4

0.1995 4

0.6849 5

Ž .

C 32

0.6432 5

0.1376 4

0.5707 6

4.2 2

Ž .

5.6 2

Ž .

C 33

0.6696 6

0.0561 5

0.5149 6

Ž .

C 34

0.7700 6

Ž .

0.0319 5

Ž .

0.5749 7

Ž .

5.4 2

Ž .

6.1 2

bidden processes 33 . The emissive state is most likely

C 35

0.8435 5

0.0904 5

0.6879 8

)

.¹Ž

. x

to be d_{x y}d_p.

Ž .

5.2 2

C 36

0.8185 5

0.1713 5

0.7425 7

Ž .

3.5 1

C 37

0.7215 4

0.3044 4

0.9130 5

Ž .

5.2 2

C 38

0.7231 6

0.2245 5

0.9753 6

Ž .

6.1 2

C 39

0.7387 6

0.2285 5

1.1098 7

Ž .

5.5 2

C 40

0.7539 5

0.3143 6

1.1895 6

Table 5

Ž .

5.3 2

C 41

0.7519 5

0.3948 5

1.1349 7

Ž .

Selected bond lengths A and angles 8 for 2

Ž .

0.3894 4

Ž .

4.3 2

C 42

0.7357 5

0.9985 6

Ž . Ž .

Ž .

3.3 1

B 1

0.6958 5

0.3001 5

0.7511 6

W 1 –C 2 1.964 7

Ž . Ž .

Ž .

W 1 –C 3

1.800 6

Ž . Ž .

Ž .

2.264 5

W 1 –N 1

^IIIŽ

. Ž

w x

Ž . Ž .

Ž .

2.266 5

W 1 –N 2

complexes TACN Cr₂m-OH m-CO₃

29 and

w x

19 . For example,

^IIIŽ

. Ž

Ž . Ž .

Ž .

2.316 5

W 1 –N 3

TACN Cr₂m-OH m-SO₃

Ž . Ž .

Ž .

C 3 –C 4

1.456 8

the mean Cr–O hydroxyl distances in complex 3 and

Ž . Ž .

Ž .

C 1 –O 1

1.162 8

TACN Cr₂m-OH m-CO₃^2qare 1.963 and 1.995

^IIIŽ

. Ž

Ž . Ž .

Ž .

C 2 –O 2

1.163 8

A 29 respectively. There has been no previous report

on structures containing the PhCH₂CO₂moiety as a

bridging ligand, although a structural account of the

Ž . Ž . Ž .

Ž .

174.4 4

W 1 –C 3 –C 4

Ž . Ž . Ž .

W 1 –C 1 –O 1

Ž .

177.1 6

Ž . Ž . Ž .

Ž .

W 1 –C 2 –O 2

175.7 7

Ž . Ž . Ž .

Ž .

171.7 2

N 1 –W 1 –C 1

Me₃TACN ₂Cr₂^IIIm-O m-

. Ž .Ž

related derivative

Ž . Ž . Ž .

Ž .

168.9 2

N 2 –W 1 –C 2

Ž . Ž . Ž .

Ž .

mean Cr–O oxo contacts 1.850 A has

O₂CMe

²w

Ž .

178.1 2

N 3 –W 1 –C 3

appeared 30 .

(

)

F.-W. Lee et al.rJournal of Organometallic Chemistry 552 1998 255–263

259

Table 6

complex 2 causes a shorter-lived emissive state com-

Atomic coordinates and B_isorB_eqfor 2

Atom

pared to neutral analogues 33 . Compounds 1a and 1b

are not emissive in solution or solid state at room

temperature.

B_eq

Ž .

0.0883 5

Ž .

y0.00304 2

Ž .

3.339 7

W 1

0.26225 2

0.16814 2

Ž .

y0.0910 6

Ž .

7.5 2

O 1

Ž .

y0.0255 4

Compounds 1a and 2 exhibit identical electrochemi-

cal in acetonitrile; they are both reversibly reduced at

y2.15 V vs. Cp₂Fe^0rqand irreversibly oxidized at

0.77 V vs. Cp₂Fe^0rq. Metal-based processes are dis-

counted since the redox potentials are independent of

the metals. It is well established that Me₃TACN can

Ž .

y0.1612 6

Ž .

7.5 2

O 2

0.3819 5

0.0588 4

Ž .

0.0871 5

Ž .

3.8 1

N 1

0.3879 4

0.3083 3

Ž .

0.1471 5

Ž .

4.1 1

N 2

0.1995 4

0.2403 4

Ž .

0.2019 5

Ž .

3.9 1

N 3

Ž .

0.3777 4

0.1429 3

Ž .

y0.0548 7

Ž .

4.8 2

C 1

0.1535 6

0.0462 5

Ž .

y0.1022 6

Ž .

4.4 2

C 2

0.3400 6

0.1029 5

Ž .

y0.1639 6

Ž .

3.4 1

C 3

0.1764 4

0.1884 4

tolerate drastic redox conditions 17 . Hence the irre-

versible wave is assigned to oxidation of the terminal

carbonyl groups which leads to dissociation from the

metal centres. The reversible couple is ascribed to a

reduction centred at the phenyl ring. Complex 1b ex-

hibits only an irreversible wave at q0.86 V vs.

Cp₂Fe^0rqwhereas 3 does not display any couples in

the potential range accessible in acetonitrile.

Ž .

y0.2999 6

Ž .

3.2 1

C 4

Ž .

0.1121 5

0.1985 4

Ž .

y0.3210 7

Ž .

5.0 2

C 5

0.0656 6

0.2805 5

Ž .

y0.4502 10

Ž .

7.1 3

C 6

0.0007 7

0.2885 7

Ž .

6.7 3

C 7

y0.0176 6

0.2166 7

y0.5557 9

Ž .

0.0270 6

Ž .

y0.5372 7

Ž .

5.4 2

C 8

Ž .

C 10

0.1366 6

Ž .

4.1 2

C 9

0.0904 5

0.1296 5

y0.4088 6

Ž .

y0.0101 7

Ž .

5.6 2

0.4361 6

0.3427 5

Ž .

4.9 2

C 11

0.3239 6

0.3788 5

0.1173 7

Ž .

5.0 2

C 12

0.2631 6

0.3446 5

0.2039 7

Ž .

5.7 2

C 13

0.0800 6

0.2392 6

0.0865 7

Ž .

5.3 2

C 14

0.2193 6

0.1826 6

0.2558 7

Ž .

5.5 2

C 15

0.3419 7

0.1718 5

0.3133 6

Ž .

5.5 2

3. Experimental details

C 16

0.3871 6

0.0387 5

0.1985 7

Ž .

4.6 2

C 17

0.4876 5

0.1986 5

0.2246 6

Ž .

4.5 2

C 18

0.4812 5

0.3025 5

0.2131 6

3.1. General procedures

Ž .

3.7 2

C 19

0.7159 5

0.2001 4

0.6831 6

Ž .

C 20

0.6409 5

0.1361 5

0.5695 6

4.2 2

Ž .

5.7 2

Ž .

C 21

0.6669 7

0.0539 5

0.5142 7

All operations were carried out using standard

Schlenk techniques under an atmosphere of nitrogen.

Diethyl ether, n-pentane and tetrahydrofuran were dried

and distilled from sodiumrbenzophenone mixture.

Ž .

5.7 2

Ž .

6.0 2

C 22

0.7675 7

Ž .

0.0315 5

Ž .

0.5719 9

Ž .

0.6856 10

C 23

0.8432 6

0.0924 6

Ž .

5.6 2

Ž .

3.5 1

Ž .

5.5 2

Ž .

6.7 2

Ž .

5.6 2

Ž .

5.1 2

C 24

0.8182 5

0.1734 5

0.7379 8

Ž .

C 25

0.7213 4

0.3077 4

0.9122 6

Ž .

C 26

0.7250 6

Ž .

0.2277 5

Ž .

0.9741 7

Ž .

Dichloromethane for reactions was dried over phos-

C 27

0.7412 7

0.2333 6

1.1099 8

Ž .

phoric V oxide and stored in purified nitrogen, and

Ž .

C 28

0.7546 6

0.3182 7

1.1900 7

for photophysics washed with concentrated sulphuric

Ž .

C 29

0.7501 6

0.3990 6

1.1345 7

acid, 10% NaHCO₃and water, then dried by CaCl₂and

distilled over CaH₂. Acetonitrile was distilled over

KMnO₄and then CaH . The compounds

Ž .

C 30

0.7338 5

Ž .

0.3927 5

Ž .

0.9986 7

Ž .

4.4 2

Ž .

3.3 1

C 31

0.5654 5

0.3122 4

0.6855 6

Ž .

C 32

0.4820 5

0.2401 5

0.6886 6

3.9 2

Ž .

4.5 2

Ž . xw

x w x²

Ž .

C 33

0.3727 5

0.2489 5

0.6469 6

CO M5C O Ph NMe₄35 MsCr, Mo, W were

Ž .

C 34

0.3413 5

Ž .

0.3290 6

Ž .

0.6007 6

Ž .

4.7 2

Ž .

4.6 2

prepared according to literature methods. Oxalyl chlo-

ride was used as received. Pyridine was freshly distilled

from potassium hydroxide pellets prior to use. Com-

C 35

0.4197 6

0.4011 5

0.5964 7

Ž .

3.9 2

C 36

0.5293 5

0.3922 4

0.6371 6

Ž .

3.4 1

C 37

0.7787 5

0.3856 4

0.7198 6

Ž .

4.3 2

C 38

0.8808 5

0.4356 5

0.8149 6

pounds Cl CO py₂M[CPh MsCr, Mo, W were

Ž .

5.0 2

C 39

0.9521 5

0.5011 5

0.7842 7

prepared as described for the bromo analogue 36

except oxalyl chloride was used. TACN and Me₃TACN

Ž .

5.2 2

C 40

0.9250 6

0.5212 5

0.6580 8

Ž .

4.6 2

C 41

0.8267 6

0.4729 5

0.5596 7

were prepared by literature methods 37 .

Ž .

4.0 2

C 42

0.7571 5

0.4068 5

0.5908 6

Ž .

3.4 2

B 1

0.6948 5

0.3018 5

0.7489 7

Elementary analyses were performed by the Butter-

worth Laboratory, UK. IR spectra were recorded on a

BIO-RAD FTS-7 FT IR spectrophotometer. ¹H, ¹³C and

³¹P NMR spectra were recorded on Bruker SPX300 or

SPX500 Spectrometers. Chemical shifts were refer-

enced to tetramethylsilane. Mass spectra were obtained

from Finnigan Mat 95 mass spectrometer. UV–Vis

absorption spectra were measured on a Perkin Elmer

Lambda 19 UV–Vis–NIR spectrometer. Cyclic Voltam-

metry was performed on a Princeton Applied Research

w x

Bocarsly et al. 32 and Xue et al. 31 suggested that

auxiliary ligands on carbyne complexes should have a

significant effect on their luminescent properties. Kostic

and Fenske 34 reported that the LUMO of Group 6

phenylcarbyne analogues are antibonding combinations

of carbyne pp– and metal dp– orbitals and that UV–Vis

radiation could promote metal-based electrons to the

carbyne carbon. In this study, incorporation of a neutral

PAR model 273 potentiostat coupled to a Houseton

2000 x–y recorder. A conventional two compartment

macrocyclic ligand into the W IV cationic carbyne

cell was used with silver–silver nitrate 0.1 mol dm

(

)

260

F.-W. Lee et al.rJournal of Organometallic Chemistry 552 1998 255–263

Fig. 3. UV–Vis spectrum of complex 2 CH₂Cl₂

in acetonitrile as reference electrode. Ferrocenium–fer-

146.1 ipso-PhC , 136.7 o-PhB , 131.0 o-PhC , 130.0

0rq

rocene Cp₂Fe

standard. Edge-plane pyrolytic graphite and platinum

were used as working and auxiliary electrodes respec-

couple was used as the internal

m-PhC , 129.5 p-PhC , 126.6 m-PhB , 122.7 p-

PhB , 60.1, 59.7, 57.7 CH₂, 56.7, 51.4 CH₃; IR

n_COKBr : 1982s, 1906s cm^y1. UV–Vis l_max, nm log

tively. Tetra-n-butylammonium hexafluorophosphate

´ in CH₂Cl₂: 247 4.34 , 324 3.96 , 464 2.08 . Calc.

for C₄₂H₄₆N₃O₂BMo M_r731.60 : C, 68.95; H, 6.34;

0.1 mol dm

was used as the supporting electrolyte.

Steady-state emission spectra were recorded on a SPEX

1681 FLUOROLOG-2 series F111AI spectrometer. The

emission lifetimes were determined and flash-photolysis

measurements were performed with a Quanta Ray

N, 5.74. Found: C, 69.12; H, 6.40; N, 5.58. FAB-MS:

mrz 414 M –BPh₄.

[( ( )

)

(

) (

)]

3.3. TACN Mo CO ₂[CPh BPh₄1b

DCR-3 pulsed Nd-YAG laser system pulse output 355

nm, 8 ns . The emission signals were detected by a

Ž .

To a solution of TACN 0.130 g, 1.01 mmol in THF

Hamamatsu R928 photomultiplier tube and recorded on

a Tektronix model 2430 digital oscilloscope.

10 ml was added Cl CO py₂Mo[CPh 0.4 g, 0.92

mmol at ambient temperature. The orange–yellow so-

lution was stirred at 50 8C for 8 h. After cooling to

ambient temperature, the yellow precipitate was col-

lected and re-dissolved in warm water. The extract was

treated with a saturated aqueous solution of NaBPh₄to

precipitate the product. This was filtered and recrystal-

[( ( )

)

(

) (

)]

3.2. Me₃TACN Mo CO ₂[CPh BPh₄1a

To a solution of Me₃TACN 0.394 g, 2.3 mmol in

te tra h y d ro fu ra n

1 0 m l

w a s a d d e d

Cl CO py₂Mo[CPh 1.0 g, 2.3 mmol and the resul-

tant red solution was stirred at 50 8C for 8 h. After

cooling, the yellow precipitate was collected by filtra-

tion and extracted into distilled water. Addition of a

saturated aqueous solution of sodium tetraphenylborate

to this afforded a yellow microcrystalline solid. Suitable

crystals for X-ray crystallography were obtained from a

lized from acetone–n-pentane to yield a yellow crys-

talline product. Yield: 0.48 g 76% . H NMR d₆-

acetone : d 7.41y6.77 m, 25H, PhC and PhB ; 6.25

br, 2H, NH ; 4.92 br, 1H, NH ; 3.48y3.37 m, 8H,

C H₂C H₂; 3.15y2.94 m, 4H, C H₂; ¹³C

Ä¹

NMR d₆-acetone : d 294.3 CPh ; 225.8 CO ; 146.1

. Ž . Ž . Ž

ipso-PhC ; 136.7 o-PhB ; 130.1 o-PhC ; 129.7 m-

dichloromethane–n-pentane solution at y20 8C. Yield:

. Ž . Ž . Ž .

PhC ; 129.1 p-PhC ; 126.6 m-PhB ; 122.7 p-PhB ;

1.35 g 80% . H NMR d₆-acetone : d 7.54 m, 2H,

o-PhC , 7.47 m, 1H, p-PhC , 7.40 m, 2H, m-PhC ,

7.28 m, 8H, o-PhB , 7.00 t, 8H, m-PhB , 6.84 t, 4H,

p-PhB , 3.50 m, 4H, C H₂, 3.40 s, 6H, C H₃, 3.37

m, 4H, C H₂, 3.17 m, 4H, C H₂, 2.94 s, 3H, C H₃.

49.9, 49.8, 47.7 CH₂; n_COKBr : 1997s, 1914s cm

;

n_NHKBr : 3258s cm^y1; UV–Vis l_max, nm log ´ in

Ž . Ž .

CH₂Cl₂: 336 3.98 . Calc. for C₃₉H₄₀N₃O₂BMo M_r

689.52 : C, 67.94; H, 5.85; N, 6.09. Found: C, 68.02;

Ä¹

C H NMR d₆-acetone : d 298.0 CPh , 225.2 CO ,

H, 5.84; N, 5.98. FAB-MS: mrz 372 M –BPh₄.

(

)

F.-W. Lee et al.rJournal of Organometallic Chemistry 552 1998 255–263

261

Fig. 4. Emission spectrum of complex 2 at room temperature l_exs330 nm, CH₃CN .

[(

) ( ) (

)]

( )

. Ž . Ž . Ž

o-PhC , 129.9 m-PhC , 129.2 p-PhC , 126.6 m-

3.4. Me₃TACN W CO ₂[CPh BPh₄

PhB , 122.7 p-PhB , 61.1, 60.6, 58.6 CH₂, 57.6,

52.3 CH₃; IR n_COKBr : 1975s, 1879s cm^y1. UV–Vis

Ž . Ž .

A solution of Me₃TACN 0.654 g, 3.8 mmol in

tetrahydrofuran 10 ml was added to a solution of

Ž . Ž . Ž .

l_max, nm log ´ in CH₂Cl₂: 250 4.19 , 328 3.90 ,

Cl CO py₂W[CPh 2.0 g, 3.8 mmol in tetrahydrofu-

462 2.38 . Calc. for C₄₂H₄₆N₃O₂BW M_r819.51 : C,

61.56; H, 5.66; N, 5.13. Found: C, 61.66; H, 5.80; N,

5.02. FAB-MS: mrz 500 M –BPh₄.

ran 10 ml and the resulting red solution was stirred at

508C for 6 h. The yellow precipitate formed was col-

lected by filtration and dried in vacuo. The product was

extracted into distilled water and treatment with a satu-

rated aqueous solution of sodium tetraphenylborate af-

forded a yellow microcrystalline solid. Suitable crystals

for X-ray crystallography were obtained from cooling of

[(

)

(

)( )

Me₃TACN ₂Cr₂m-OH m-O₂CCH₂Ph ₂PF₆

) ](

3.5.

( )

A solution of Me₃TACN 0.096 g, 0.56 mmol in

a dichloromethane–n-pentane solution. Yield: 2.66 g

THF 10 ml was added to

Cl CO py₂Cr[CPh 0.20 g, 0.5 mmol in THF at 08C.

solution of

85% . H NMR d₆-acetone : d 7.40 m, 5H, PhC ,

7.28 m, 8H, o-PhB , 7.00 t, 8H, m-PhB , 6.84 t, 4H,

The resulting solution was allowed to warm to ambient

temperature and stirred for 2 days to give a pale green

precipitate and green solution. The precipitate was fil-

tered, washed with THF and re-dissolved in water. Solid

NH₄PF₆was added to the aqueous solution to precipi-

p-PhB , 3.95 m, 4H, C H₂, 3.45 s, 6H, C H₃, 3.37

m, 4H, C H₂, 3.15 m, 4H, C H₂, 2.92 s, 3H, C H₃.

Ä¹

C H NMR d₆-acetone : d 288.4 broad, CPh ,

224.6 CO , 149.9 ipso-PhC , 136.7 o-PhB , 130.0

(

)

262

F.-W. Lee et al.rJournal of Organometallic Chemistry 552 1998 255–263

tate a red product. Yield: 0.2 g 33% . Recrystallization

at ambient temperature by diffusion of diethyl ether into

an acetonitrile solution gave red crystals suitable for

reflections minimum and maximum transmission fac-

tors 0.340 and 1.000 . Upon averaging the 5095 reflec-

tions, 4844 of which were uniquely measured, R_ints

X-ray crystallography. n_CONujol : 1577 cm^y1. Calc.

for C₃₄H₅₇N₆O₅Cr₂F₁₈P₃M_r1168.78 : C, 34.94; H,

4.92; N, 7.19. Found: C, 35.31; H, 5.06; N, 7.04.

FAB-MS: mrz 358 Me₃TACN Cr PhCH₂CO₂

Ž .

0.014 . 4362 reflections with I)3s I were consid-

ered observed and used in the structural analysis. The

structure was solved by heavy-atom Patterson methods,

expanded using Fourier techniques 38 and refined by

full-matrix least squares using the MSC-Crystal Struc-

3.6. Structural determination of 1a

ture Package TeXsan 39 on a Silicon Graphics Indy

computer. The 49 non-H atoms were refined anisotropi-

cally and the 46H atoms at calculated positions with

thermal parameters equal to 1.3 times that of the at-

tached C atoms were not refined. Convergence for 442

variable parameters by least squares refinement on F

A pale yellow plate shaped crystal of dimensions

0.15=0.10=0.30 mm was used for data collection at

301 K on a Rigaku AFC7R diffractometer with graphite

monochromatized Mo–K a radiation ls0.71073 A

with ws4F_o²rs ²F_o, where s F_os s I q

²Ž

²Ž .

using v–2u scans with v-scan angle 0.68q0.35 tan

Ž .

for 4362 reflections with I)3s I was

u 8 at a scan speed of 16.0 deg min

up to 4 scans for

0.010 F_o

Ž ..

reflection I-15 s I . Intensity data in the range of

2u_maxs458; h: 0 to 14; k:y15 to 15; l: y11 to 11 and

3 standard reflections measured after every 300 reflec-

reached at Rs0.031 and wRs0.037 with a goodness-

of-fit of 2.46. Drs _maxs0.05. The final difference

Fourier map was featureless, with maximum positive

tions showed decay of 1.27% , were corrected for decay

and negative peaks of 1.24 and 1.16 e A respectively.

and for Lorentz and polarization effects, and empirical

absorption corrections based on the c-scan of four

strong reflections minimum and maximum transmis-

4. Supplementary material

sion factors 0.945 and 1.000 . Upon averaging the 5132

reflections, 4874 of which were uniquely measured,

Listings of crystal data and refinement, atomic coor-

dinates, calculated coordinates, thermal parameters,

bond lengths and angles and structure factors for 1a, 2

and 3 are available as Supplementary Material from the

authors.

Ž .

R_ints0.048 , 3780 reflections with I)3 s I were

considered observed and used in the structural analysis.

The structure was solved by Patterson methods, ex-

w x.

panded by Fourier methods PATTY 38 and refined

by full-matrix least squares using the software package

TeXsan 39 on a Silicon Graphics Indy computer. The

46 H atoms at calculated positions with thermal parame-

ters equal to 1.3 times that of the attached C atoms were

not refined. Convergence for 442 variable parameters

Acknowledgements

We thank The University of Hong Kong and the

Hong Kong Research Grants Council for financial sup-

port.

by least squares refinement on

with w s

4F_o²rs ²F_o, where s F_os s I q 0.010 F_o

2 2

²Ž

²Ž .

Ž .

. x

for 6327 reflections with I)3 s I was reached at

Rs0.042 and wRs0.051 with a goodness-of-fit of

2.02. Drs _maxs0.01. The final difference Fourier

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Products guided by the article

Product name:[Mo(CO)2(CPh)(1,4,7-trimethyl-1,4,7-triazacyclononane)]BPh₄

Cas No:206865-96-5

R&D Labs maybe for 206865-96-5

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