Synthesis, characterization and reactivity of the molybdenum(VI) complex [MoCl(NAr)2(CH2CMe2Ph)] (Ar=2,6-Pri2C6H3)

Journal of Organometallic Chemistry 689 (2004) 332–344

www.elsevier.com/locate/jorganchem

Synthesis, characterization and reactivity of the

molybdenum(VI) complex [MoCl(NAr)₂(CH₂CMe₂Ph)]

(Ar ¼ 2,6-Prⁱ₂C₆H₃)

a

b,

a

Vernon C. Gibson , Carl Redshaw ^*, Gary L.P. Walker ,

c

William Clegg , Mark R.J. Elsegood

d

a

Department of Chemistry, Imperial College, South Kensington, London SW7 2AY, UK

Wolfson Materials and Catalysis Centre, School of Chemical Sciences and Pharmacy, The University of East Anglia, Norwich NR4 7TJ, UK

b

c

School of Natural Sciences (Chemistry), University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU, UK

d

Chemistry Department, Loughborough University, Loughborough, Leicestershire LE11 3TU, UK

Received 15 September 2003; accepted 18 October 2003

Abstract

The compounds [MoCl(NAr)₂R] (R ¼ CH₂CMe₂Ph (1) or CH₂CMe₃(2); Ar ¼ 2,6-Prⁱ₂C₆H₃) have been prepared from

[MoCl₂(NAr)₂(dme)] (dme ¼ 1,2-dimethoxyethane) and one equivalent of the respective Grignard reagent RMgCl in diethyl ether.

Similarly, the mixed-imido complex [MoCl₂(NAr)(NBu^t)(dme)] aﬀords [MoCl(NAr)(NBu^t)(CH₂CMe₂Ph)] (3). Chloride substitu-

tion reactions of 1 with the appropriate lithium reagents aﬀord the compounds [MoCp(NAr)₂(CH₂CMe₂Ph)] (4) (Cp ¼ cyclopen-

tadienyl), [MoInd(NAr)₂(CH₂CMe₂Ph)] (5) (Ind ¼ Indenyl), [Mo(OBu^t)(NAr)₂(CH₂CMe Ph)] (6), [MoMe(NAr)₂(CH₂CMe₂Ph)]

2

(7), [MoMe(PMe₃)(NAr)₂(CH₂CMe Ph)] (8) (formed in the presence of PMe₃) and [Mo(NHAr)(NAr)₂(CH₂CMe₂P h)](9). In the

2

latter case, a by-product {[Mo(NAr)₂(CH₂CMe₂Ph) ]₂(l-O)}(10) has also been isolated. The crystal structures of 1, 4, 5 and 10 have

been determined. All possess distorted tetrahedral metal centres with cis near-linear arylimido ligands; in each case (except 5, for

which the evidence is unclear) there are a-agostic interactions present.

Keywords: Synthesis; Bis(imido) molybdenum; Monoalkyl; Crystal structures; Agostic interactions

1. Introduction

sively studied by Morrison and Wigley [3]. We have now

extended our studies to the monoalkyl complexes

[MoCl(NAr)₂(R)] (R ¼ CH₂CMe₂Ph and CH₂CMe₃)

and describe a number of derivatives made by replacing

Cl with carbon, oxygen and nitrogen ligands.

We have reported the synthesis and characterization

of a number of four-coordinate bis(imido) dialkyl com-

plexes of the form [Mo(NR¹)(NR²)(R³)₂] (R¹¼ CMe₃,

R²¼ 2,6-Prⁱ₂C₆H₃), R³¼ CH₂CMe₃) and their sub-

sequent reactions with phenols to yield well-deﬁned

metathesis catalysts [1a]. We have also described the

mixed-imido dialkyls [Mo(NR¹)(NR²)(R³)₂] (R¹¼ CMe₃,

R²¼ C₆F₅, R³¼ CH₂CMe₂Ph) [1b]. Subsequently, some

related compounds such as {MoCpCl[(CH₂)_n(2-C₆

H₄N)₂]} and {Mo(OBu^t)₂[(CH₂)_n(2-C₆H₄N)₂]} (n ¼ 1;2)

were prepared [2]. The synthesis and reactivity of the d⁰

[Mo(NAr)₃] core (Ar ¼ 2,6-Prⁱ₂C₆H₃) has been exten-

2. Results and discussion

Interaction of [MoCl₂(NAr)₂(dme)] (Ar ¼ 2,6-Prⁱ₂C₆

H₃) with one equivalent of Grignard reagent RMgCl in

diethyl ether at )78 °C aﬀords, after work-up, multigram

quantities of the monoalkyl complexes [MoCl(NAr)₂R]

(R ¼ CH₂CMe₂Ph (1) or CH₂CMe₃(2)) as orange–red

crystalline solids. The compounds doubtless have the

same basic structure; the molecular structure of 1, deter-

mined by X-ray crystallography, is shown in Fig. 1, and

selected bond lengths and angles are given in Table 1.

^*Corresponding author. Tel.: +44-1603-593137; fax: +44-1603-

592003.

E-mail address: Carl.Redshaw@uea.ac.uk (C. Redshaw).

doi:10.1016/j.jorganchem.2003.10.020

V.C. Gibson et al. / Journal of Organometallic Chemistry 689 (2004) 332–344

333

The coordination geometry about the metal centre is

best described as distorted tetrahedral with angles in the

range 99.91(7)°–122.67(5)°. The two cis imido groups

are similar; the Mo–N distances are essentially equal,

ꢀ

1.7364(15) and 1.7435(15) A, with Mo–N–C angles of

161.59(13)° and 152.94(12)°, respectively. The latter is

considered to be at the lower limit regarded as a ÔlinearÕ

imido group acting as a four-electron donor [4]. An in-

teresting feature is the presence of an a-agostic interac-

tion involving a hydrogen atom H(1A) on the neophyl

methylene carbon. The metal–hydrogen distance (re-

ꢀ

sulting from free reﬁnement) is 2.46(2) A with an Mo–

C(1)–H(1A) angle of 100.0(13)°, comparable with the

two a-agostic interactions found in the related mixed-

imido complex [Mo(NAr)(NBu^t)(CH₂CMe₃)₂] [1].

The mixed-imido complex [MoCl(NAr)(NBu^t)(CH₂

CMe₂Ph)] (3) is similarly formed from [MoCl₂(NAr)

(NBu^t)(dme)] and neophyl Grignard in diethyl ether.

The mono-neophyl complex 1 is a useful starting

material for the synthesis of four- and ﬁve-coordinate

Fig. 1. Molecular structure of 1, without most H atoms and minor

disorder components, and with key atoms labelled. Displacement el-

lipsoids here and in other ﬁgures are drawn at the 50% probability level.

Table 1

ꢀ

Selected bond lengths (A) and angles (°) for 1

Mo–Cl

Mo–N(1)

2.3295(5)

1.7364(15)

1.401(2)

Mo–C(1)

Mo–N(2)

N(2)–C(23)

2.1296(18)

1.7435(15)

1.399(2)

N(1)–C(11)

Cl–Mo–C(1)

Cl–Mo–N(2)

C(1)–Mo–N(2)

Mo–C(1)–C(2)

Mo–N(2)–C(23)

122.67(5)

108.24(5)

99.91(7)

Cl–Mo–N(1)

C(1)–Mo–N(1)

N(1)–Mo–N(2)

Mo–N(1)–C(11)

111.53(5)

105.07(7)

108.21(7)

161.59(13)

115.55(12)

152.94(12)

Prⁱ

PrⁱPrⁱ

Prⁱ

v)

Prⁱ

N

vi)

N

Prⁱ

R

Prⁱ

R

Mo

O

N

Me

N

HN

N

Me

PMe₃

R

Prⁱ

8

7

9

10

iv)

vi)

Prⁱ

N

Prⁱ

R

Mo

N

Cl

1

Prⁱ

i)

iii)

ii)

Prⁱ

N

Prⁱ

R

OBu^t

Prⁱ

R

Mo

N

Prⁱ

6

4

5

Scheme 1. Reagents and conditions. (i) LiCp, )78 °C, Et₂O, 24 h; (ii) Li(Indenyl), )78 °C, Et₂O, 24 h; (iii) LiOBu^t, )78 °C, Et₂O, 12 h; (iv) MeMgI,

78 °C, Et₂O, 12 h; (v) PMe₃, )198 °C, pentane; (vi) LiNHAr, Et₂O, 1 h; (vii) [dried in vacuo, 50 °C, 12 h; Et₂O, 48 h, 25 °C] ꢀ 3.

334

V.C. Gibson et al. / Journal of Organometallic Chemistry 689 (2004) 332–344

Table 2

¹H NMR data (benzene-d₆,^aCDCl₃,^b298 K)

Compound

Shift

Rel. integration

Multiplicity

J (Hz)

Assignment

1^a

7.43

7.24

2

d

³J_HH8.5

³J_HH7.7

*

o-C₆H₅

m-C₆H₅

t

7.12

1

d

p-C₆H₅

o, m, p-C₆H₅

CHMe₂

6.92–6.85

3.59

3.01

5

m

sept

4

³J_HH6.9

2

s

t

CH₂CMe₂Ph

CHMe₂

1.57

1.08

6

24

³J_HH7.1

i

2^a

6.96–6.88

3.67

2.79

6

4

m

sept

s

m, p-C₆H₃Pr₂

CHMe₂

³J_HH6.9

2

CH₂CMe₃

CHMe₂

1.23

1.13

6

s

12

d

³J_HH6.9

1.09

d

CHMe₂

3^a

7.39

2

dd

³J_HH8.0

⁴J_HH0.8

³J_HH7.7

³J_HH7.3

o-C₆H₅

7.22

7.09

2

3

2

1

3

6

9

t

m-C₆H₅

p-C₆H₅

m, p-C₆H₃Pr₂

t

i

7.04–6.90

3.58

3.18

m

sept

d

s

³J_HH6.8

²J_HH13.5

CHMe₂

CH₂CMe₂Ph

CHMe₂

2.37

1.58

1.54

1.28

s

d

s

³J_HH6.8

1.23

1.00

CHMe₂

NCMe₃

4^b

7.62

7.46

2

d

³J_HH7.6

³J_HH7.7

³J_HH7.2

³J_HH7.7

o-C₆H₅

m-C₆H₅

p-C₆H₅

t

7.32

7.02

1

t

i

4

d

m-C₆H₃Pr₂

i

6.95–6.91

5.77

3.54

2

m

s

p-C₆H₃Pr₂

C₅H₅

CHMe₂

5

4

sept

s

³J_HH6.9

3.02

1.42

2

CH₂CMe₂Ph

CHMe₂

6

12

s

1.14

d

³J_HH6.9

5^b

7.79

7.59

2

1

2

8

d

t

³J_HH7.8

³J_HH7.7

³J_HH7.3

o-C₆H₅

m-C₆H₅

p-C₆H₅

H_5;6-C₉H₇

7.40

7.06

t

m

i

6.96–6.82

m, p-C₆H₃Pr₂

H_4;7-C₉H₇

H_1;3-C₉H₇

H₂-C₉H₇

6.10

5.93

3.19

2.66

1.49

1.06

2

1

d

³J_HH3.0

³J_HH3.3

t

br. sept

4

CHMe₂

2

s

CH₂CMe₂Ph

CHMe₂

6

24

s

pseudo t

³J_HH6.5

6^a

7.53

2

dd

³J_HH8.1

⁴J_HH1.1

³J_HH7.8

o-C₆H₅

7.21

7.08–6.90

2

7

t

m-C₆H₅

m, p-C₆H₃Pr₂

m

i

3.73

3.06

1.68

1.29

1.14

4

2

sept

s

³J_HH6.9

CHMe₂

CH₂CMe₂Ph

OCMe₃

6

s

9

24

s

d

³J_HH6.9

CHMe₂

V.C. Gibson et al. / Journal of Organometallic Chemistry 689 (2004) 332–344

335

Table 2 (continued)

Compound

7^b

Shift

Rel. integration

Multiplicity

J (Hz)

Assignment

7.65

7.43

2

d

³J_HH7.5

³J_HH7.3

³J_HH7.1

o-C₆H₅

m-C₆H₅

p-C₆H₅

t

7.34

1

t

i

7.10–6.95

3.47

2.48

6

m

sept

s

m, p-C₆H₃Pr₂

CHMe₂

4

³J_HH6.8

2

CH₂CMe₂Ph

CHMe₂

1.65

1.11

6

s

12

3

d

³J_HH6.8

1.08

0.37

d

CHMe₂

CH₃

s

8^a

7.51

2

dd

³J_HH8.4

⁴J_HH1.2

³J_HH7.3

o-C₆H₅

7.18

7.04–6.95

2

7

t

m-C₆H₅

p-C₆H₅

m, p-C₆H₃Pr₂

m

i

3.89

2.53

1.51

1.24

1.17

0.91

0.79

4

2

sept

s

³J_HH6.8

CHMe₂

CH₂CMe₂Ph

CHMe₂

6

s

12

3

d

s

³J_HH6.8

CHMe₂

CH₃

PMe₃

9

d

³J_HP4.5

9^b

7.61

7.32

2

s

o-C₆H₅

m-C₆H₅

p-C₆H₅

NHAr

t

7.20–6.80

11

m

i

C₆H₃Pr₂

NHAr

NAr

CHMe₂

3.46

3.40

2.81

1.65

1.32

1.26

2

4

t

sept

³J_HH6.8

2

s

CH₂CMe₂Ph

CHMe₂

6

s

12

d

³J_HH6.8

CHMe₂

10^a

7.58

2

dd

³J_HH8.4

⁴J_HH1.0

³J_HH7.3

³J_HH7.4

o-C₆H₅

7.21

7.04

2

1

t

m-C₆H₅

p-C₆H₅

m, p-C₆H₃Pr₂

d

i

6.92–6.85

3.71

3.29

6

m

sept

s

4

³J_HH6.8

CHMe₂

2

CH₂CMe₂Ph

CHMe₂

1.86

1.15

6

s

12

d

³J_HH6.8

1.07

d

CHMe₂

11^b

7.49

7.30

2

1

7

d

t

³J_HH8.4

³J_HH7.7

³J_HH7.5

o-C₆H₅

m-C₆H₅

p-C₆H₅

NH^tBu

7.15

7.10–6.80

t

m

i

m, p-C₆H₃Pr₂

CHMe₂

3.48

2.55

1.55

1.18

1.07

1.04

4

2

sept

s

³J_HH6.8

CH₂CMe₂Ph

NCMe₃

6

s

9

s

12

d

³J_HH6.9

CHMe₂

s, Singlet; d, doublet; t, triplet; q, quartet; sept, septet; m, multiplet; br, broad; *, obscured.

336

V.C. Gibson et al. / Journal of Organometallic Chemistry 689 (2004) 332–344

Table 3

¹³C NMR data (benzene-d₆,^aCdCl₃, 298 K)

b

Compound

Shift

Multiplicity

J (Hz)

Assignment

1^a

153.17

148.31

143.31s

129.30

m

o-C₆Hⁱ₃Pr₂

ipso-C₆H₅

ipso-C₆Hⁱ₃Pr₂

p-C₆Hⁱ₃Pr₂

dd

¹J_CH160.2

²J_CH8.1

*

127.49

127.19

126.33

123.02

73.87

m

dt

m

th

m-C₆H₅

p-C₆H₅

o-C₆H₅

m-C₆Hⁱ₃Pr₂

CH₂CMe₂Ph

*

¹J_CH157.74

¹J_CH159.3

¹J_CH126.4

³J_CH4.8

39.58

31.99

s

qq

CH₂CMe₂Ph

¹J_CH126.0

³J_CH4.4

28.70

23.70

d

¹J_CH128.3

¹J_CH126.2

³J_CH5.0

CHMe₂

qt

23.54

qt

¹J_CH126.2

³J_CH5.0

CHMe₂

2^a

155.22

143.22

127.58

123.05

77.51

s

ipso-C₆Hⁱ₃Pr₂

o-C₆Hⁱ₃Pr₂

p-C₆Hⁱ₃Pr₂

m-C₆Hⁱ₃Pr₂

CH₂CMe₃

CHCMe₂

s

d

t

*

¹J_CH157.8

¹J_CH120.7

33.53

32.62

s

q

d

q

s

¹J_CH124.2

¹J_CH127.5

¹J_CH127.9

28.93

23.49

CHCMe₂

3^a

153.69

149.96

141.79

128.94

ipso-C₆Hⁱ₃Pr₂

ipso-C₆H₅

o-C₆Hⁱ₃Pr₂

o-C₆H₅

s

dd

¹J_CH

*

²J_CH7.6

126.67

126.49

d

¹J_CH160.1

¹J_CH160.4

²J_CH7.5

p-C₆H₅

p-C₆Hⁱ₃Pr₂

dt

126.01

122.93

73.41

71.16

39.41

32.57

32.04

30.98

28.81

23.76

23.33

153.60

152.56

140.98

128.20

dt

m

s

¹J_CH159.9

¹J_CH157.1

m-C₆H₅

m-C₆Hⁱ₃Pr₂

NCMe₃

t

¹J_CH125.6

CH₂CMe₂Ph

NCMe₃

s

q

d

q

s

¹J_CH126.3

¹J_CH126.2

¹J_CH127.4

¹J_CH128.2

¹J_CH125.9

CHMe₂

4^b

ipso-C₆Hⁱ₃Pr₂

ipso-C₆H₅

o-C₆Hⁱ₃Pr₂

o-C₆H₅

s

dd

¹J_CH160.0

²J_CH7.7

126.04

125.73

dt

¹J_CH156.5

²J_CH6.9

¹J_CH160.8

²J_CH7.4

p-C₆Hⁱ₃Pr₂

p-C₆H₅

123.74

122.38

d

ddd

¹J_CH159.8

¹J_CH155.1

²J_CH7.2

m-C₆H₅

m-C₆Hⁱ₃Pr₂

³J_CH5.1

105.91

47.60

41.80

m

t

¹J_CH175.2

¹J_CH126.3

C₅H₅

CH₂CMe₂Ph

s

V.C. Gibson et al. / Journal of Organometallic Chemistry 689 (2004) 332–344

337

Table 3 (continued)

Compound

Shift

34.16

Multiplicity

J (Hz)

Assignment

q

d

q

s

¹J_CH126.0

¹J_CH126.3

CH₂CMe₂Ph

CHMe₂

27.68

23.88

23.83

CHMe₂

5^b

153.17

152.64

141.00

128.26

127.68

126.60

125.96

ipso-C₆Hⁱ₃Pr₂

ipso-C₆H₅

o-C₆Hⁱ₃Pr₂

o-C₆H₅

s

m

s

*

ipso-C₉H₇

m-C₆H₅

p-C₆H₅

m

dt

*

¹J_CH162.4

²J_CH7.0

125.61

dd

¹J_CH160.4

²J_CH7.6

C_4;7-C₉H₇

123.88

122.06

121.31

m

¹J_CH159.6

¹J_CH155.5

¹J_CH164.4

²J_CH4.9

p-C₆Hⁱ₃Pr₂

m-C₆Hⁱ₃Pr₂

C_5;6-C₉H₇

m

dd

110.44

dt

¹J_CH171.7

²J_CH4.2

C₂-C₉H₇

89.94

51.29

41.32

Br. d

t

¹J_CH172.5

¹J_CH126.3

C_1;3-C₉H₇

CH₂CMe₂Ph

CHMe₂

s

34.58

27.63

q

¹J_CH126.0

¹J_CH128.3

¹J_CH125.7

¹J_CH125.5

d

24.56

22.90

qt

s

CHMe₂

6^a

153.47

152.37

142.28

128.49

125.87

125.79

125.75

122.84

81.84

ipso-C₆Hⁱ₃Pr₂

ipso-C₆H₅

o-C₆Hⁱ₃Pr₂

o-C₆H₅

s

dd

m

d

²J_CH16.2

*

p-C₆Hⁱ₃Pr₂

*

p-C₆H₅

¹J_CH160.1

¹J_CH155.9

m-C₆H₅

m

s

m-C₆Hⁱ₃Pr₂

OC(CH₃)₃

CH₂CMe₂Ph

OC(CH₃)₃

CHMe₂

63.68

39.71

t

¹J_CH125.6

s

32.62

32.32

q

¹J_CH125.9

¹J_CH128.0

¹J_CH125.5

q

28.60

23.74

d

q

CHMe₂

7^b

152.73

148.52

142.33

128.98

s

ipso-C₆Hⁱ₃Pr₂

ipso-C₆H₅

o-C₆Hⁱ₃Pr₂

o-C₆H₅

s

dd

¹J_CH

*

²J_CH7.4

¹J_CH160.8

²J_CH7.1

126.84

126.25

dt

p-C₆H₅

¹J_CH

*

p-C₆Hⁱ₃Pr₂

²J_CH5.9

125.24

122.32

72.03

d

t

¹J_CH159.2

¹J_CH155.3

¹J_CH123.4

m-C₆H₅

m-C₆Hⁱ₃Pr₂

CH₂CMe₂Ph

CH₃

38.70

34.86

s

q

m

d

q

s

¹J_CH126.8

¹J_CH128.8

¹J_CH128.4

¹J_CH126.3

¹J_CH125.0

32.75

28.13

CH₂CMe₂Ph

CHMe₂

23.47

23.13

CHMe₂

8^a

153.46

153.19

143.36

128.78

ipso-C₆Hⁱ₃Pr₂

ipso-C₆H₅

o-C₆Hⁱ₃Pr₂

o-C₆H₅

s

dd

²J_CH6.1

338

V.C. Gibson et al. / Journal of Organometallic Chemistry 689 (2004) 332–344

Table 3 (continued)

Compound

Shift

Multiplicity

J (Hz)

Assignment

125.98

125.91

125.43

122.90

59.19

m

d

m

t

*

p-C₆Hⁱ₃Pr₂

p-C₆H₅

*

¹J_CH159.2

¹J_CH159.7

¹J_CH125.9

m-C₆H₅

m-C₆Hⁱ₃Pr₂

CH₂CMe₂Ph

CHMe₂

41.09

33.13

s

m

d

q

dq

s

¹J_CH123.6

¹J_CH126.2

¹J_CH125.9

¹J_CH125.8

²J_CP5.2

28.18

24.70

CHMe₂

CH₃

CHMe₂

23.98

23.55

14.74

PMe₃

9^b

152.54

148.63

142.41

138.99

125.13

123.38

122.92

122.31

66.57

ipso-NHC₆Hⁱ₃Pr₂

ipso-NC₆Hⁱ₃Pr₂

o-NC₆Hⁱ₃Pr₂

o-NHC₆Hⁱ₃Pr₂

p-NC₆Hⁱ₃Pr₂

p-NHC₆Hⁱ₃Pr₂

m-NHC₆Hⁱ₃Pr₂

m-NC₆Hⁱ₃Pr₂

CH₂CMe₂Ph

CHMe₂

s

d

m

t

¹J_CH159.9

¹J_CH160.1

*

¹J_CH121.8

39.84

32.18

s

q

d

q

s

¹J_CH126.5

¹J_CH127.4

¹J_CH125.9

¹J_CH125.8

¹J_CH125.9

28.28

24.05

CHMe₂

23.61

23.23

CHMe₂

10^a

153.69

153.01

142.52

128.59

ipso-C₆Hⁱ₃Pr₂

ipso-C₆H₅

o-C₆Hⁱ₃Pr₂

o-C₆H₅

s

dd

¹J_CH

*

²J_CH7.6

126.40

125.96

d

¹J_CH159.9

¹J_CH161.2

²J_CH7.6

p-C₆Hⁱ₃Pr₂

p-C₆H₅

dt

125.49

dt

¹J_CH154.3

²J_CH6.9

m-C₆H₅

122.86

68.54

39.88

m

t

¹J_CH156.3

¹J_CH124.3

m-C₆Hⁱ₃Pr₂

CH₂CMe₂Ph

C HMe₂

s

31.83

28.78

q

d

qt

s

¹J_CH128.6

¹J_CH127.6

¹J_CH125.9

¹J_CH125.7

23.78

23.51

CHMe₂

11^b

152.96

152.62

141.59

128.00

126.02

ipso-C₆Hⁱ₃Pr₂

ipso-C₆H₅

o-C₆Hⁱ₃Pr₂

m-C₆H₅

s

m

dt

¹J_CH149.0

¹J_CH156.2

²J_CH7.0

p-C₆Hⁱ₃Pr₂

125.25

dt

¹J_CH159.9

²J_CH7.3

p-C₆H₅

124.40

122.26

61.55

57.78

39.91

33.18

32.80

28.29

23.42

23.09

d

m

s

¹J_CH159.4

¹J_CH156.8

o-C₆H₅

m-C₆Hⁱ₃Pr₂

NCMe₃

t

¹J_CH120.9

CH₂CMe₂Ph

NCMe₃

s

q

d

m

¹J_CH125.8

¹J_CH126.5

¹J_CH127.4

¹J_CH125.8

¹J_CH125.9

CH₂CMe₂Ph

CHMe₂

s, Singlet; d, doublet; t, triplet; q, quartet; sept, septet; m, multiplet; br, broad; *, obscured.

V.C. Gibson et al. / Journal of Organometallic Chemistry 689 (2004) 332–344

339

bis(imido) complexes of molybdenum(VI); see Scheme 1.

NMR data (¹H and ¹³C) of complexes 1 through 11 are

presented in Tables 2 and 3.

171.11(14)°. Interestingly, there is also a similar a-agostic

interaction involving H(1B) and the metal centre: Mo–

ꢀ

H(1B) ¼ 2.56(2) A, Mo–C(1)–H(1B) ¼ 99.0(11)°. The

Interaction of 1 with LiCp (Cp ¼ cyclopentadienyl)

or LiInd (Ind ¼ Indenyl) in diethyl ether at )78 °C

gives the compounds [MoR⁰(NAr)₂(CH₂CMe₂Ph)]

(R⁰¼ Cp (4) or Ind (5)), respectively, in high yields.

These compounds are very soluble in hydrocarbons

and can be crystallized from pentane at )40 °C. The

molecular structure of 4 is shown in Fig. 2, with se-

lected bond lengths and angles in Table 4. The mole-

cule has a distorted tetrahedral geometry with an

approximate (i.e. non-crystallographic) mirror plane

of symmetry containing the metal and the methylene

C(1) atom of the neophyl group and bisecting the Cp

ligand.

related compound [CpMo(NAr)₂(NHAr)] has been

reported previously [3].

The structure of the compound [MoInd(NAr)₂

(CH₂CMe₂Ph)] (5) is shown in Fig. 3; selected bond

lengths and angles are given in Table 5. As previously

observed in compounds 1 and 4, the geometry about the

molybdenum centre is distorted tetrahedral with near-

linear cis arylimido ligands (Mo–N–C ¼ 157.41(14)° and

169.35(16)°). The bonding of the indenyl ring, for which

the Mo–C distances diﬀer signiﬁcantly, in the range

3

ꢀ

2.350(2)–2.641(2) A, is best described as slipped, i.e. g .

The indenyl ring also displays a slight puckering; the

greatest deviations from the mean plane of the ring at-

ꢀ

The angles around the molybdenum centre vary from

95.85(6)° to 106.33(7)°, excluding the angles involving

the Cp ring carbon atoms. The Mo–C (Cp) bond lengths

ꢀ

range from 2.3927(18) to 2.5081(18) A, indicating a

slight tilting away from the sterically bulky neophyl

group. As in 1, the two imido groups are similar: Mo–N

oms are for C(36) ()0.0451 A) and C(37) (+0.0450 A) (+

denotes closer to the metal). There is no clear evidence

ꢀ

of a-agostic bonding in 5 (Mo–H(1A) ¼ 2.61(3) A, Mo–

ꢀ

H(1B) ¼ 2.58(3) A). We note that Sundermeyer and

coworkers [5] have recently reported a number of

bis(imido) indenyl complexes of molybdenum.

ꢀ

1.7610(15) and 1.7693(14) A, Mo–N–C 163.99(14)° and

Fig. 2. Molecular structure of 4, without most H atoms and minor

disorder components, and with key atoms labelled.

Fig. 3. Molecular structure of 5, without most H atoms, and with key

atoms labelled.

Table 4

ꢀ

Selected bond lengths (A) and angles (°) for 4

Mo–C(1)

Mo–C(12)

2.2103(17)

2.4101(18)

2.5081(18)

1.7693(14)

1.385(2)

Mo–C(11)

Mo–C(13)

2.3927(18)

2.4983(18)

2.4690(18)

1.7610(15)

1.392(2)

Mo–C(14)

Mo–N(1)

Mo–C(15)

Mo–N(2)

N(1)–C(16)

C(1)–Mo–N(1)

N(1)–Mo–N(2)

Mo–N(1)–C(16)

N(2)–C(28)

C(1)–Mo–N(2)

Mo–C(1)–C(2)

Mo–N(2)–C(28)

95.85(6)

106.33(7)

163.99(14)

95.91(7)

126.49(12)

171.11(14)

340

V.C. Gibson et al. / Journal of Organometallic Chemistry 689 (2004) 332–344

Table 5

ꢀ

Selected bond lengths (A) and angles (°) for 5

Mo–C(1)

Mo–N(2)

2.209(2)

Mo–N(1)

Mo–C(35)

1.7674(16)

2.496(2)

2.350(2)

1.7568(15)

2.397(2)

2.594(2)

Mo–C(36)

Mo–C(38)

Mo–C(37)

Mo–C(39)

2.641(2)

98.76(8)

C(1)–Mo–N(1)

N(1)–Mo–N(2)

Mo–N(1)–C(11)

101.36(8)

106.90(8)

157.41(14)

C(1)–Mo–N(2)

Mo–C(1)–C(2)

Mo–N(2)–C(23)

125.87(14)

169.35(16)

The chloro ligands of 1 can be cleanly replaced by

treatment with LiOBu^tto give the corresponding four-

coordinate species [Mo(OBu^t)(NAr)₂(CH₂CMe₂Ph)]

(6), and with MeMgBr to give [MoMe(NAr)₂(CH₂

CMe₂Ph)] (7). In the presence of PMe₃, the latter reac-

tion gives a ﬁve-coordinate adduct [MoMe(PMe₃)

(NAr)₂(CH₂CMe₂Ph)] (8), the NMR data of which

contain a doublet (³J_HP4.5 Hz) for the methyl groups at

ca. 0.8 ppm (¹H), and a singlet (ca. )36.5 ppm) in the ³¹

NMR spectrum.

P

Interaction of 1 with LiNHAr in diethyl ether at

)78 °C gives an orange solution from which Mo(N-

HAr)(NAr)₂(CH₂CMe₂Ph)] (9) can be isolated together

with a second product {[Mo(NAr)₂(CH₂CMe₂Ph)]₂

(l-O)} (10), which has been structurally characterized

(Fig. 4, Table 6). The molecule (approximate C₂axis

through O(1)) consists of two tetrahedral [Mo(NAr)₂

(CH₂CMe₂Ph)] fragments linked by a pseudo-linear oxo

bridge (Mo–O–Mo ¼ 157.61(9)°). The similar Mo–

ꢀ

N(imido) bond lengths 1.7467(19)–1.7572(19) A and

Mo–N–C angles 156.23(16)°–164.57(18)° are consistent

with all imido ligands acting as four-electron donors.

There is evidence of an a-agostic interaction involving

ꢀ

Mo(2): Mo(2)–H(11A) 2.51(3) A, Mo(2)–H(11B) 2.67(3)

ꢀ

A. Disorder in the alkyl group attached to Mo(1) pre-

cludes an assessment of any a-agostic interaction for it.

The Mo–C–C angles of 117.37(17)° and 118.05(16)° are

somewhat smaller than those found in 4 (126.49(12)°)

and 5 (125.87(14)°), doubtless a reﬂection of the lack of

steric congestion provided by the presence of the oxo

ligand (cf. 1 (115.55(12)°). A number of systems in-

volving l-O ligation in the presence of terminal imido

groups have been structurally characterised [6]. The

origin of the oxo group in 10 is uncertain. It is possible

that oxygen could be extracted from the solvent diethyl

Fig. 4. Molecular structure of 10, without most H atoms and minor

disorder components, and with key atoms labelled.

Table 6

ꢀ

Selected bond lengths (A) and angles (°) for 10.C₅H₁₂

Mo(1)–O

Mo(1)–N(1)

Mo(2)–O

1.9010(15)

1.7572(19)

1.8996(15)

1.7528(19)

1.397(3)

Mo(1)–C(1)

Mo(1)–N(2)

Mo(2)–C(11)

Mo(2)–N(4)

N(2)–C(33)

N(4)–C(45)

2.150(2)

1.7467(19)

2.143(2)

1.7511(19)

1.392(3)

1.401(3)

Mo(2)–N(3)

N(1)–C(21)

N(3)–C(57)

1.395(3)

O–Mo(1)–C(1)

O–Mo(1)–N(2)

114.17(8)

O–Mo(1)–N(1)

113.77(8)

113.93(8)

101.92(9)

111.31(8)

113.19(8)

102.91(9)

157.61(9)

118.4(3)

C(1)–Mo(1)–N(1)

N(1)–Mo(1)–N(2)

O–Mo(2)–N(3)

102.11(8)

109.72(9)

113.43(8)

104.30(9)

110.84(9)

117.37(17)

118.05(15)

164.57(18)

162.46(18)

C(1)–Mo(1)–N(2)

O–Mo(2)–C(11)

O–Mo(2)–N(4)

C(11)–Mo(2)–N(3)

N(3)–Mo(2)–N(4)

Mo(1)–C(1)–C(2)

Mo(2)–C(11)–C(12)

Mo(1)–N(2)–C(33)

Mo(2)–N(4)–C(45)

C(11)–Mo(2)–N(4)

Mo(1)–O–Mo(2)

Mo(1)–C(1)–C(2A)

Mo(1)–N(1)–C(21)

Mo(2)–N(3)–C(57)

156.23(16)

160.24(17)

V.C. Gibson et al. / Journal of Organometallic Chemistry 689 (2004) 332–344

341

ether; however, the formation of oxo species from water

is well known; Sundermeyer et al. [7] have demonstrated

the complete conversion of imido molybdenum species

to their oxo counterparts.

1043s, 1029s, 982s, 933m, 903w, 840w, 798s, 768m, 753s,

723m, 701s, 649w, 631w, 619w, 593w, 568m, 550s, 537s.

3.3. Preparation of [MoCl(NAr)₂(CH₂CMe₃)] (2)

In conclusion, the chemistry described herein shows

that complexes of the form [MoCl(NAr)₂R] (R ¼ CH₂

CMe₂Ph or CH₂CMe₃; Ar ¼ 2,6-Prⁱ₂C₆H₃) provide a

useful entry, via chloride substitution reactions, to four-

and ﬁve-coordinate bis(imido) monoalkyl chemistry.

As for 1, but using [MoCl₂(NAr)₂(dme)] (5.04 g, 8.3

mmol) and Me₃CCH₂MgCl (10.4 cm³, 0.8 M, 8.3

mmol). Yield: 40%. Found: C, 61.37; H, 7.75; N, 5.47%.

MoClN₂C₂₉H₄₅requires C, 62.98; H, 8.20; N, 5.06%.

IR: 3058m, 2724m, 2660m, 1921w, 1858w, 1619w,

1585w, 1572w, 1520w, 1364 s, 1261m, 1231w, 1177w,

1143w, 1098m, 1056m, 1045m, 1018m, 934w, 863w, 797

vs, 754s, 662vw, 634vw, 618vw, 580vw, 561vw, 535w,

505vw, 488vw, 461w, 386 vw, 374w, 352s, 328m. M.S.

(CI): 590 [M + H + Cl]^þ, 554 [M + H]^þ, 482 [M–

CH₂CMe₃]^þ, 440 [M–CH₂CMe₃–ⁱPr]^þ; (EI, m/z): 589

[M + Cl]^þ, 554 [M + H]^þ, 482 [M–CH₂CMe₃]^þ, 440 [M–

CH₂CMe₃–ⁱPr]^þ.

3. Experimental

3.1. General

All manipulations were carried out under an atmo-

sphere of nitrogen using standard Schlenk and cannula

techniques or in a conventional nitrogen-ﬁlled glove-

box. Solvents were reﬂuxed over an appropriate drying

agent, and distilled and degassed prior to use. Elemental

analyses were performed by the microanalytical services

of the Department of Chemistry at Durham, Medac

Ltd. and at Imperial College. NMR spectra were re-

corded on a Varian VXR 400 S spectrometer at 400.0

MHz (¹H), 100.6 MHz (¹³C) and 100.0 MHz (³¹P);

chemical shifts are referenced to the residual protio

impurity of the deuterated solvent. IR spectra (nujol

mulls, KBr or CsI windows) were recorded on Perkin–

Elmer 577 and 457 grating spectrophotometers.

[MoCl₂(NAr)₂(dme)] and [MoCl₂(NBu^t)(NAr)(dme)]

were prepared by literature methods [8,9]. Trimethyl-

phosphine was prepared by the method of Wolfsberger

and Schmidbaur [10]. Grignard reagents were prepared

from RCl and activated Mg in diethyl ether. All other

chemicals were obtained commercially and used as re-

ceived unless stated otherwise.

3.4. Preparation of [MoCl(NAr)(NBu^t)(CH₂CMe₂Ph)]

(3)

As for 1, but using [MoCl₂(NAr)(NBu^t)(dme)] (4.88

g, 9.7 mmol) and PhMe₂CCH₂MgCl (12.9 cm³, 0.75 M,

9.7 mmol). Yield: 3.5 g, 71%. Found: C, 60.96; H, 7.74;

N, 5.43%. MoN₂C₂₆H₃₉requires C, 61.11; H, 7.69; N,

5.48%. IR: 3057m, 2725m, 2670m, 1599m, 1581w,

1494m, 1452vs, 1361vs, 1331s, 1308 m, 1283 s, 1215vs,

1190m, 1158w, 1132m, 1116w, 1030m, 982s, 934m,

903w, 805w, 794w, 753s, 697s, 668w, 615w, 592w, 552w,

514w, 454w, 443w, 384m, 357w, 338s, 324m. M.S: (CI)

512 [M + H]^þ; (EI) 511 [M]^þ, 476 [M–Cl + H]^þ, 378 [M–

CH₂CMe₂Ph]^þ.

3.5. Preparation of [MoCp(NAr)₂(CH₂CMe₂Ph)] (4)

To 1 (1.02 g, 1.66 mmol) and LiCp (0.12 g, 1.66

mmol) was added cold ()78 °C) diethyl ether (ca. 30

cm³). After stirring for 24 h, the volatiles were removed

and the dark red solid was extracted into pentane;

cooling ()40 °C) aﬀorded 4. Yield: 0.52 g, 49%. Found:

C, 72.72; H, 8.35; N, 4.47%. MoN₂C₃₉H₅₂requires C,

72.65; H, 8.13; N, 4.56%. IR: 3129w, 3088w, 3052w,

1599w, 1586m, 1494m, 1422s, 1360s, 1336, 1262s,

1224m, 1192m, 1175m, 1159m, 1136m, 1098s, 1075m,

1062m, 1033m, 1020m, 966s, 931m, 834w, 806s, 768s,

746s, 704s, 615w, 599w, 561m, 538m. M.S. (CI) 647

[M + H]^þ, 513 [M–CH₂CMe₂Ph]^þ, 471 [M–CH₂CMe₂

Ph–CHCMe₂]^þ, 350 [M–CH₂CMe₂Ph–C₅H₅]^þ; (EI, m/z)

646 [M]^þ, 513 [M–CH₂CMe₂Ph]^þ; (FAB^þ, m/z) 646

[M]^þ, 513 [M–CH₂CMe₂Ph]^þ.

3.2. Preparation of [MoCl(NAr)₂CH₂CMe₂Ph] (1)

To a solution of [MoCl₂(NAr)₂(dme)] (5.04 g, 8.3

mmol) in diethyl ether (ca. 100 cm³) at )78 °C was

slowly added (over about 20 min) CH₂CMe₂PhMgCl

(12.2 cm³, 0.68 M solution, 8.3 mmol) in diethyl ether

(ca. 10 cm³). After slowly warming to ambient temper-

ature and stirring for 12 h the orange suspension was

ﬁltered. The remaining solid was further extracted with

diethyl ether (2 ꢀ 50 cm³) and pentane (50 cm³). The

volatiles were removed from the combined extracts, af-

fording a red solid. Extraction into pentane (ca. 60 cm³)

and cooling ()78 °C) gave 1 as orange–red crystals.

Yield: 3.28 g, 64%. Found: C, 66.17; H, 7.80; N, 4.71%.

MoClN₂C₃₄H₄₇requires C, 66.39; H, 7.70; N, 4.55%.

IR: 1599w, 1576m, 1569m, 1494m, 1467s, 1461s, 1456s,

1451s, 1446s, 1425s, 1377s, 1360s, 1324s, 1289s, 1273s,

1223m, 1190m, 1175m, 1158m, 1144m, 1103s, 1057s,

3.6. Preparation of [MoInd(NAr)₂(CH₂CMe₂Ph)] (5)

As for 4, but using 1 (0.77 g, 1.25 mmol) and Li(In-

denyl) (0.15 g, 1.25 mmol), aﬀording 5 as red prisms.

342

V.C. Gibson et al. / Journal of Organometallic Chemistry 689 (2004) 332–344

Yield: 0.56 g, 64%. Found: C, 66.42; H, 6.63; N, 4.59%.

MoN₂C₃₄H₅₁requires C, 66.38; H, 6.92; N, 4.69%. IR:

2556w, 2721w, 2692w, 2612w, 2360w, 2342w, 1949w,

1939w, 1912w, 1707w, 1694w, 1666w, 1651w, 1634w,

1622w, 1597m, 1596m, 1567m, 1539w, 1513w, 1493s,

1463s, 1456s, 1435s, 1429s, 1418s, 1377s, 1359s, 1322s,

1304s, 1284s, 1261s, 1224s, 1186s, 1178s, 1158m, 1151m,

1101s, 1087m, 1059s, 1045m, 1034s, 1001w, 975s, 942s,

909m, 841m, 805s, 798m, 765s, 757s. M.S. (CI) 696

[M + H]^þ; (EI, m/z) 695 [M]^þ, 580 [M–C₉H₇]^þ, 443 [M–

C₉H₇–C₆Hⁱ₃Pr₂]^þ; (FAB^þ, m/z) 695 [M]^þ, 580 [M–

C₉H₇]^þ, 443 [M–C₉H₇–C₆H₃ⁱPr₂]^þ.

solution obtained was ﬁltered and concentrated under

reduced pressure. Cooling ()35 °C) overnight aﬀorded 8

as an orange microcrystalline solid (Yield: 0.30 g, 53%).

Found: C, 67.85; H, 8.96; N, 4.19%. MoPN₂C₃₈H₅₉

requires C, 68.04; H, 8.87; N, 4.18%. IR: 3028m, 2721w,

1597m, 1586m, 1567m, 1539w, 1493s, 1456vs, 1435vs,

1429vs, 1418vs, 1359vs, 1322vs, 1304s, 1284vs, 1261vs,

1224m, 1186m, 1178m, 1158m, 1151m, 1101s, 1087m,

1059s, 1045m, 1034s, 1001vw, 975vs, 942vs, 909m,

841m, 805m, 798m, 765vs, 757vs, 700vs, 667m, 615m.

³¹P NMR (C₆D₆, 298K): d )36.49 (s, PMe₃).

3.10. Preparation of [Mo(NHAr)(NAr)₂(CH₂CMe₂

Ph)] (9)

3.7. Preparation of [Mo(OBu^t)(NAr)₂(CH₂CMe₂Ph)]

(6)

Chilled ()78 °C) diethyl ether was added to a solid

mixture of 1 (0.59 g, 9.6 mmol) and LiNHAr (0.18 g, 9.6

mmol) at )78 °C. The resultant solution was allowed to

warm to room temperature, stirred for 1 h and then

ﬁltered. Volatiles were removed in vacuo and extraction

into pentane followed by cooling ()35 °C) aﬀorded or-

ange crystals of 9. Yield: 0.32 g, 44%. Found: C, 72.43;

H, 8.46; N, 5.35%. MoN₃C₄₆H₆₅requires C, 73.08; H,

8.67; N, 5.56%. IR: 3303m, 1569m, 1362m, 1320s,

1287m, 1267s, 1245m, 1223m, 1191s, 1158m, 1109m,

1071m, 1056m, 1044m, 1031m, 981s, 932m, 904m, 886m,

855s, 837w, 796s, 764m, 750vs, 697s, 634w, 625w, 552m,

508m, 480m, 456w, 421m. M.S. (CI) 756 [M]^þ; (EI, m/z)

756 [M]^þ, 624 [M–CH₂CMe₂Ph]^þ, 581 [M–CH₂CMe₂

Ph–CHCMe₂]^þ.

To 1 (0.98 g, 1.6 mmol) and LiOBu^t(0.13 g, 1.6 mmol)

was added cold ()78 °C) diethyl ether. After stirring at 25

°C for 12 h, the volatiles were removed in vacuo, and the

residue was extracted with pentane (ca. 20 cm³). Cooling

()40 °C) aﬀorded 6 as red needles. Yield 0.43 g, 42%.

Found: C, 69.96; H, 8.37; N, 4.60%. MoON₂C₃₈H₅₆re-

quires C, 69.92; H, 8.65; N, 4.29%. IR: 3056m, 2754w,

2722w, 2671w, 1599m, 1584m, 1569m, 1539w, 1516w,

1495m, 424s, 1361s, 1324s, 1278vs, 1250s, 1235m,

1224m, 1168s, 1100m, 1072m, 1057m, 1045m, 1032m,

982vs, 952vs, 838w, 787s, 751vs, 711m, 698s, 661w, 635w,

596m, 571m, 563m, 538w, 505m, 476vw, 449w, 428w.

M.S. (CI) 654 [M + H]^þ, 596 [M–^tBu]^þ; (EI, m/z) 786

[M + CH₂CMe₂Ph]^þ, 726 [M + O^tBu]^þ, 654 [M + H]^þ,

596 [M–^tBu]^þ, 580 [M–O^tBu]^þ, 520 [M–CH₂CMe₂Ph]^þ,

463 [M–CH₂CMe₂Ph–^tBu]^þ.

3.11. Preparation of {[Mo(NAr)₂(CH₂CMe₂Ph)]₂

(l-O)} (10)

3.8. Preparation of [MoMe(NAr)₂(CH₂CMe₂Ph)] (7)

3.11.1. From LiNHAr

As for 6, but using 1 (1.02 g, 1.66 mmol) and MeMgI

(0.55 cm³, 3.0 M solution, 1.66 mmol), aﬀording 7 as

orange crystals. Yield: 0.45 g, 46%. Sticky nature of

product resulted in inconsistent microanalysis. IR:

3054s, 2721m, 1599m, 1576m, 1569m, 1494m, 1467vs,

1456vs, 1451vs, 1446vs, 1425s, 1360s, 1324s, 1289m,

1273s, 1223m, 1190m, 1175m, 1158m, 1144m, 1103s,

1057m, 1043m, 1029m, 982m, 933m, 903w, 865w, 856w,

840w, 798s, 768m, 753vs, 701s, 666w, 649w, 631w, 619m,

593m. M.S. (CI) 596 [M + H]^þ, 581 [M–CH₃+ H]^þ, 477

[M– CMe₂Ph + H]^þ, 463 [M–CH₂Me₂Ph + H]^þ.

To an ampoule charged with a solid mixture of 1

(0.59 g, 0.96 mmol) and LiNHAr (0.18 g, 0.96 mmol)

at )78 °C was added chilled ()78 °C) diethyl ether

(50 cm³). The resultant solution was allowed to warm

to room temperature and stirred for 48 h. All volatile

components were removed under reduced pressure

and the mixture heated to 50 °C for 12 h. The re-

action mixture was then redissolved in diethyl ether

(50 cm³), stirred for a further 48 h, volatile compo-

nents removed under reduced pressure, then heated to

50 °C. This process was repeated a further three

times. The resultant dark red oil was extracted into

minimal pentane and cooled to )35 °C, aﬀording

red–orange, solvent-dependent crystals of 10 (Yield:

0.73 g, 65%).

3.9. Preparation of [MoMe(PMe₃)(NAr)₂(CH₂CMe₂

Ph)] (8)

Pentane (30 cm³) was added to an ampoule charged

with 7 (0.5 g, 0.84 mmol). The resultant red solution was

frozen ()198 °C) and placed under vacuum. Trimeth-

ylphosphine (0.076 g, 1.0 mmol) was added to the so-

lution (vacuum-transfer) and the mixture was allowed to

warm slowly to room temperature. The dark orange

3.11.2. From LiNHBu^t

Chilled ()78 °C) diethyl ether was added to a solid

mixture of 1 (0.95 g, 1.54 mmol) and LiNHBu^t(0.122 g,

1.54 mmol) at )78 °C. The resultant solution was al-

V.C. Gibson et al. / Journal of Organometallic Chemistry 689 (2004) 332–344

343

Table 7

Crystallographic data

Compound

1

4

5

10 ꢁ pentane

Formula

M

C₃₄H₄₇ClMoN₂

615.1

C₃₉H₅₂MoN₂

644.8

C₄₃H₅₄MoN₂

694.8

C₆₈H₉₄Mo₂N₄O ꢁ C₅H₁₂

1247.5

triclinic

Crystal system

Space group

monoclinic

P2₁=c

16.6488(13)

16.2054(13)

11.9638(9)

monoclinic

P2₁=n

17.5013(12)

11.3724(8)

19.2673(14)

orthorhombic

P2₁2₁2₁

12.8531(9)

26.3545(17)

11.1511(8)

ꢁ

P1

ꢀ

a (A)

12.5275(5)

13.3471(6)

21.2886(9)

78.547(2)

ꢀ

b (A)

ꢀ

c (A)

a (°)

b (°)

c (°)

92.260(2)

113.065(1)

83.159(2)

86.315(2)

3460.8(3)

2

3

ꢀ

U (A )

3225.3(4)

4

1.267

3528.3(4)

4

1.214

3777.3(5)

4

1.222

Z

D_c(g cm^ꢂ3

)

1.197

0.41

l (mm^ꢂ1

)

0.51

19 428

7350

0.40

23 377

8096

0.38

24 256

8790

Data measured

Unique data

R_int

27 405

15 259

0.0168

854

0.0319

374

0.0266

422

0.0203

432

Parameters

R ðF ; F ²> 2rÞ

R_wðF ², all data)

0.0270

0.0712

0.38, )0.51

0.0297

0.0710

0.39, )0.55

0.0262

0.0650

0.48, )0.40

0.0350

0.0893

0.88, )0.56

ꢂ3

ꢀ

Max., min. el. density (eA

)

lowed to warm to room temperature and stirred for

2 days. All volatiles were removed in vacuo and the re-

sultant solid redissolved in diethyl ether (50 cm³) and

stirred for a further 2 days. This process was repeated a

further three times. The resultant orange solid was ex-

tracted into pentane and cooled ()35 °C) to aﬀord or-

ange, solvent-dependent crystals of 10 (Yield: 1.11 g,

61%). Found: C, 69.43; H, 8.26; N, 4.95%.

Mo₂ON₄C₆₈H₉₄requires C, 69.49; H, 8.06; N, 4.77%.

IR: 3054m, 1598w, 1568m, 1495m, 1424vs, 1362m,

1333s, 1322s, 1273s, 1223w, 1178w, 1158w, 1100m,

1076m, 1058m, 1045m, 1031m, 983m, 933w, 903w, 796s,

770vs, 698m, 644w, 594w, 559w, 537w, 456w. M.S. (EI)

604 [1/2M + O]^þ.

657m, 623m, 602m, 586m, 554m, 539w, 452w, 436w.

M.S. (EI): 595 [M–C(CH₃)₃]^þ.

3.13. X-ray crystallography

Table 7 gives information on the crystal structure

determinations for 1, 4, 5 and 10. All data were mea-

ꢀ

sured at 160 K with Mo Ka radiation (k ¼ 0:71073 A)

on a Siemens SMART CCD diﬀractometer, using ﬁne-

slice x scans [11]. Corrections for absorption were based

on multiple and symmetry-equivalent reﬂections [12].

The structures were solved by direct methods, and re-

ﬁned on F²values for all unique data. Anisotropic dis-

placement parameters were reﬁned for all non-hydrogen

atoms except low-occupancy disorder components, and

H atoms were constrained except for metal-bonded CH₂

groups, which were freely reﬁned to investigate a-agostic

interactions. Two-fold disorder was resolved and reﬁned

for some isopropyl substituents, and for one complete

ligand in 10, with the aid of restraints. For the non-

centrosymmetric 5, the absolute structure was conﬁrmed

by reﬁnement of an enantiopole parameter to 0.00(2) [13].

3.12. Preparation of Mo(NAr)₂(CH₂CMe₂Ph)(NHBu^t)

(11)

Chilled ()78 °C) diethyl ether was added to a solid

mixture of 1 (0.95 g, 1.55 mmol) and LiNHBu^t(0.12 g,

1.55 mmol) at )78 °C. The resultant solution was al-

lowed to warm to room temperature and stirred for 1 h.

The resultant dark orange solution was ﬁltered from the

white precipitate and all volatile components removed

under reduced pressure, yielding an orange solid. Ex-

traction into pentane followed by removal of volatiles in

vacuo aﬀorded 11 as an orange oil (yield: 0.41 g, 41%).

IR: 3265m, 3057s, 3021s, 2965–2869vs, 2802w, 1599m,

1586w, 1570vw, 1495s, 1446vs, 1425vs, 1382s, 1361s,

1337vs, 1324vs, 1275vs, 1262vs, 1206s, 1158m, 1143m,

1100, 1057s, 1045s, 1030vs, 1020vs, 983s, 970s, 933m,

909m, 867w, 840w, 797s, 785s, 768s, 751s, 736m 700s,

4. Supplementary material

Crystallographic data (excluding structure factors)

have been deposited with the Cambridge Crystallo-

graphic Data Centre, CCDC no. 217025, 217026,

217027 and 217028 for compounds 1, 4, 5 and 10, re-

spectively. Copies of this information may be obtained

free of charge from The Director, CCDC, 12 Union

Road, Cambridge CD2 1EZ, UK (fax: +44-1223-

344

V.C. Gibson et al. / Journal of Organometallic Chemistry 689 (2004) 332–344

[6] (a) A.A. Danopoulos, G. Wilkinson, B. Hussain-Bates, M.B.

Hursthouse, J. Chem. Soc., Dalton Trans. (1991) 269;

(b) A.A. Danopoulos, G. Wilkinson, T.K.N. Sweet, M.B. Hurst-

house, Polyhedron 15 (1996) 873;

336033; e-mail: deposit@ccdc.cam.ac.uk or www: http://

www.ccdc.cam.ac.uk).

(c) V. Saboonchian, A.A. Danopoulos, A. Gutierrez, G. Wilkin-

son, D.J. Williams, Polyhedron 10 (1991) 2241;

(d) A.A. Danopoulos, G. Wilkinson, D.J. Williams, J. Chem. Soc.,

Chem. Commun. (1991) 181;

Acknowledgements

(e) H.W. Lam, G. Wilkinson, D.J. Williams, Polyhedron 10 (1991)

2647;

The EPSRC is gratefully acknowledged for grants.

(f) A. Gutierrez, G. Wilkinson, B. Hussain-Bates, M.B. Hurst-

house, Polyhedron 9 (1990) 2081;

(g) J.B. Strong, B.S. Haggerty, A.L. Rheinhold, E.A. Maatta,

Chem. Commun. (1997) 1137, and references therein;

(h) V.C. Gibson, A.J. Graham, D.L. Ormsby, B.P. Ward, A.J.P.

White, D.J. Williams, J. Chem. Soc., Dalton Trans. (2002) 2597.

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2379.

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Article Doi

Synthesis, characterization and reactivity of the molybdenum(VI) complex [MoCl(NAr)2(CH2CMe2Ph)] (Ar=2,6-Pri2C6H3)

DOI: 10.1016/j.jorganchem.2003.10.020

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Full text of DOI:10.1016/j.jorganchem.2003.10.020

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