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

Article abstract of DOI:10.1016/j.jorganchem.2003.10.020

The compounds [MoCl(NAr)₂R] (R=CH₂CMe₂ Ph(1) or CH₂CMe₃(2); Ar=2,6-Prⁱ ₂C₆H₃) have been prepared from [MoCl₂(NAr)₂(dme)] (dme=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 substitution reactions of 1 with the appropriate lithium reagents afford the compounds [MoCp(NAr)₂ (CH₂CMe₂Ph)] (4) (Cp=cyclopentadienyl), [MoInd(NAr)₂(CH₂ CMe₂Ph)] (5) (Ind=Indenyl), [Mo(OBu^t)(NAr) ₂(CH₂CMe ₂Ph)] (6), [MoMe(NAr)₂(CH₂ CMe₂Ph)] (7), [MoMe(PMe₃)(NAr)₂ (CH₂CMe ₂Ph)] (8) (formed in the presence of PMe₃) and [Mo(NHAr)(NAr)₂(CH₂ CMe₂P h)](9). In the latter case, a by-product {[Mo(NAr)₂(CH₂ CMe₂Ph) ]₂ (μ-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 α-agostic interactions present.

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

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)(NBut)(dme)] affords [MoCl(NAr)(NBut)(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(OBut)(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.
Ó 2003 Elsevier B.V. All rights reserved.
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 CH2 CMe3)
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] (R1 ¼ CMe3,
R2 ¼ 2,6-Pri2C6H3), R3 ¼ 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] (R1 ¼ CMe3,
R2 ¼ C6F5, R3 ¼ CH2CMe2Ph) [1b]. Subsequently, some
related compounds such as {MoCpCl[(CH2)n(2-C6
H4N)2]} and {Mo(OBut)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).
0022-328X/$ - see front matter Ó 2003 Elsevier B.V. All rights reserved.
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)(NBut)(CH2CMe3)2] [1].
The mixed-imido complex [MoCl(NAr)(NBut)(CH2
CMe2Ph)] (3) is similarly formed from [MoCl2(NAr)
(NBut)(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
Pri
Pri
Pri
Pri Pri
Pri
Pri
Pri
Pri
Pri
Pri
v)
Pri
N
vi)
N
N
N
N
Pri
R
Pri
Pri
R
R
Mo
Mo
Mo
Mo
Mo
O
N
Me
N
N
N
HN
N
Me
PMe3
R
R
Pri
Pri
Pri
Pri
Pri
Pri
8
7
9
10
iv)
vi)
Pri
Pri
N
Pri
R
Mo
N
Cl
1
Pri
i)
iii)
ii)
Pri
Pri
Pri
Pri
Pri
Pri
N
N
N
Pri
R
OBut
Pri
Pri
R
R
Mo
Mo
Mo
N
N
N
Pri
Pri
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) LiOBut, )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,a CDCl3,b 298 K)
Compound
Shift
Rel. integration
Multiplicity
J (Hz)
Assignment
1a
7.43
7.24
2
2
d
3JHH 8.5
3JHH 7.7
*
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
3JHH 6.9
2
s
s
t
CH2CMe2Ph
CH2CMe2Ph
CHMe2
1.57
1.08
6
24
3JHH 7.1
i
2a
6.96–6.88
3.67
2.79
6
4
m
sept
s
m, p-C6H3 Pr2
CHMe2
3JHH 6.9
2
CH2CMe3
CH2CMe3
CHMe2
1.23
1.13
6
s
12
12
d
3JHH 6.9
3JHH 6.9
1.09
d
CHMe2
3a
7.39
2
dd
3JHH 8.0
4JHH 0.8
3JHH 7.7
3JHH 7.3
o-C6H5
7.22
7.09
2
2
3
2
1
1
3
3
6
6
9
t
m-C6H5
p-C6H5
m, p-C6H3 Pr2
t
i
7.04–6.90
3.58
3.18
m
sept
d
d
s
3JHH 6.8
2JHH 13.5
2JHH 13.5
CHMe2
CH2CMe2Ph
CH2CMe2Ph
CH2CMe2Ph
CH2CMe2Ph
CHMe2
2.37
1.58
1.54
1.28
s
d
d
s
3JHH 6.8
3JHH 6.8
1.23
1.00
CHMe2
NCMe3
4b
7.62
7.46
2
2
d
3JHH 7.6
3JHH 7.7
3JHH 7.2
3JHH 7.7
o-C6H5
m-C6H5
p-C6H5
t
7.32
7.02
1
t
i
4
d
m-C6H3 Pr2
i
6.95–6.91
5.77
3.54
2
m
s
p-C6H3 Pr2
C5H5
CHMe2
5
4
sept
s
3JHH 6.9
3.02
1.42
2
CH2CMe2Ph
CH2CMe2Ph
CHMe2
6
12
s
1.14
d
3JHH 6.9
5b
7.79
7.59
2
2
1
2
8
d
t
3JHH 7.8
3JHH 7.7
3JHH 7.3
o-C6H5
m-C6H5
p-C6H5
H5;6-C9H7
7.40
7.06
t
m
m
i
6.96–6.82
m, p-C6H3 Pr2
H4;7-C9H7
H1;3-C9H7
H2-C9H7
6.10
5.93
3.19
2.66
1.49
1.06
2
1
d
3JHH 3.0
3JHH 3.3
t
br. sept
4
CHMe2
2
s
CH2CMe2Ph
CH2CMe2Ph
CHMe2
6
24
s
pseudo t
3JHH 6.5
6a
7.53
2
dd
3JHH 8.1
4JHH 1.1
3JHH 7.8
o-C6H5
7.21
7.08–6.90
2
7
t
m-C6H5
m-C6H5
m, p-C6H3 Pr2
m
i
3.73
3.06
1.68
1.29
1.14
4
2
sept
s
3JHH 6.9
CHMe2
CH2CMe2Ph
CH2CMe2Ph
OCMe3
6
s
9
24
s
d
3JHH 6.9
CHMe2

V.C. Gibson et al. / Journal of Organometallic Chemistry 689 (2004) 332–344
335
Table 2 (continued)
Compound
7b
Shift
Rel. integration
Multiplicity
J (Hz)
Assignment
7.65
7.43
2
2
d
3JHH 7.5
3JHH 7.3
3JHH 7.1
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-C6H3 Pr2
CHMe2
4
3JHH 6.8
2
CH2CMe2Ph
CH2CMe2Ph
CHMe2
1.65
1.11
6
s
12
12
3
d
3JHH 6.8
3JHH 6.8
1.08
0.37
d
CHMe2
CH3
s
8a
7.51
2
dd
3JHH 8.4
4JHH 1.2
3JHH 7.3
o-C6H5
7.18
7.04–6.95
2
7
t
m-C6H5
p-C6H5
m, p-C6H3 Pr2
m
i
3.89
2.53
1.51
1.24
1.17
0.91
0.79
4
2
sept
s
3JHH 6.8
CHMe2
CH2CMe2Ph
CH2CMe2Ph
CHMe2
6
s
12
12
3
d
d
s
3JHH 6.8
3JHH 6.8
CHMe2
CH3
PMe3
9
d
3JHP 4.5
9b
7.61
7.32
2
2
s
o-C6H5
m-C6H5
p-C6H5
NHAr
t
7.20–6.80
11
m
i
C6H3 Pr2
NHAr
NAr
CHMe2
CHMe2
3.46
3.40
2.81
1.65
1.32
1.26
2
4
t
sept
3JHH 6.8
2
s
CH2CMe2Ph
CH2CMe2Ph
CHMe2
6
s
12
12
d
d
3JHH 6.8
3JHH 6.8
CHMe2
10a
7.58
2
dd
3JHH 8.4
4JHH 1.0
3JHH 7.3
3JHH 7.4
o-C6H5
7.21
7.04
2
1
t
m-C6H5
p-C6H5
m, p-C6H3 Pr2
d
i
6.92–6.85
3.71
3.29
6
m
sept
s
4
3JHH 6.8
CHMe2
2
CH2CMe2Ph
CH2CMe2Ph
CHMe2
1.86
1.15
6
s
12
12
d
3JHH 6.8
3JHH 6.8
1.07
d
CHMe2
11b
7.49
7.30
2
2
1
7
d
t
3JHH 8.4
3JHH 7.7
3JHH 7.5
o-C6H5
m-C6H5
p-C6H5
NHtBu
7.15
7.10–6.80
t
m
i
m, p-C6H3 Pr2
CHMe2
3.48
2.55
1.55
1.18
1.07
1.04
4
2
sept
s
3JHH 6.8
CH2CMe2Ph
CH2CMe2Ph
NCMe3
6
s
9
s
12
12
d
d
3JHH 6.9
3JHH 6.9
CHMe2
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,a CdCl3, 298 K)
b
Compound
Shift
Multiplicity
J (Hz)
Assignment
1a
153.17
148.31
143.31s
129.30
m
m
o-C6Hi3Pr2
ipso-C6H5
ipso-C6Hi3Pr2
p-C6Hi3Pr2
dd
1JCH 160.2
2JCH 8.1
*
127.49
127.19
126.33
123.02
73.87
m
dt
dt
m
th
m-C6H5
p-C6H5
o-C6H5
m-C6Hi3Pr2
CH2CMe2Ph
*
1JCH 157.74
1JCH 159.3
1JCH 126.4
3JCH 4.8
39.58
31.99
s
qq
CH2CMe2Ph
CH2CMe2Ph
1JCH 126.0
3JCH 4.4
28.70
23.70
d
1JCH 128.3
1JCH 126.2
3JCH 5.0
CHMe2
CHMe2
qt
23.54
qt
1JCH 126.2
3JCH 5.0
CHMe2
2a
155.22
143.22
127.58
123.05
77.51
s
ipso-C6Hi3Pr2
o-C6Hi3Pr2
p-C6Hi3Pr2
m-C6Hi3Pr2
CH2CMe3
CH2CMe3
CH2CMe3
CHCMe2
s
d
d
t
*
1JCH 157.8
1JCH 120.7
33.53
32.62
s
q
d
q
s
1JCH 124.2
1JCH 127.5
1JCH 127.9
28.93
23.49
CHCMe2
3a
153.69
149.96
141.79
128.94
ipso-C6Hi3Pr2
ipso-C6H5
o-C6Hi3Pr2
o-C6H5
s
s
dd
1JCH
*
2JCH 7.6
126.67
126.49
d
1JCH 160.1
1JCH 160.4
2JCH 7.5
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
1JCH 159.9
1JCH 157.1
m-C6H5
m-C6Hi3Pr2
NCMe3
t
1JCH 125.6
CH2CMe2Ph
CH2CMe2Ph
CH2CMe2Ph
CH2CMe2Ph
NCMe3
s
q
q
q
d
q
q
s
1JCH 126.3
1JCH 126.2
1JCH 127.4
1JCH 128.2
1JCH 125.9
1JCH 125.9
CHMe2
CHMe2
CHMe2
4b
ipso-C6Hi3Pr2
ipso-C6H5
o-C6Hi3Pr2
o-C6H5
s
s
dd
1JCH 160.0
2JCH 7.7
126.04
125.73
dt
dt
1JCH 156.5
2JCH 6.9
1JCH 160.8
2JCH 7.4
p-C6Hi3Pr2
p-C6H5
123.74
122.38
d
ddd
1JCH 159.8
1JCH 155.1
2JCH 7.2
m-C6H5
m-C6Hi3Pr2
3JCH 5.1
105.91
47.60
41.80
m
t
1JCH 175.2
1JCH 126.3
C5H5
CH2CMe2Ph
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
q
s
1JCH 126.0
1JCH 126.3
1JCH 126.3
1JCH 126.3
CH2CMe2Ph
CHMe2
CHMe2
27.68
23.88
23.83
CHMe2
5b
153.17
152.64
141.00
128.26
127.68
126.60
125.96
ipso-C6Hi3Pr2
ipso-C6H5
o-C6Hi3Pr2
o-C6H5
s
s
m
s
*
ipso-C9H7
m-C6H5
p-C6H5
m
dt
*
1JCH 162.4
2JCH 7.0
125.61
dd
1JCH 160.4
2JCH 7.6
C4;7-C9H7
123.88
122.06
121.31
m
1JCH 159.6
1JCH 155.5
1JCH 164.4
2JCH 4.9
p-C6Hi3Pr2
m-C6Hi3Pr2
C5;6-C9H7
m
dd
110.44
dt
1JCH 171.7
2JCH 4.2
C2-C9H7
89.94
51.29
41.32
Br. d
t
1JCH 172.5
1JCH 126.3
C1;3-C9H7
CH2CMe2Ph
CH2CMe2Ph
CH2CMe2Ph
CHMe2
s
34.58
27.63
q
1JCH 126.0
1JCH 128.3
1JCH 125.7
1JCH 125.5
d
24.56
22.90
qt
qt
s
CHMe2
CHMe2
6a
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
s
dd
m
m
d
2JCH 16.2
*
p-C6Hi3Pr2
*
p-C6H5
1JCH 160.1
1JCH 155.9
m-C6H5
m
s
m-C6Hi3Pr2
OC(CH3)3
CH2CMe2Ph
CH2CMe2Ph
CH2CMe2Ph
OC(CH3)3
CHMe2
63.68
39.71
t
1JCH 125.6
s
32.62
32.32
q
1JCH 125.9
1JCH 125.9
1JCH 128.0
1JCH 125.5
q
28.60
23.74
d
q
CHMe2
7b
152.73
148.52
142.33
128.98
s
ipso-C6Hi3Pr2
ipso-C6H5
o-C6Hi3Pr2
o-C6H5
s
s
dd
1JCH
*
2JCH 7.4
1JCH 160.8
2JCH 7.1
126.84
126.25
dt
dt
p-C6H5
1JCH
*
p-C6Hi3Pr2
2JCH 5.9
125.24
122.32
72.03
d
d
t
1JCH 159.2
1JCH 155.3
1JCH 123.4
m-C6H5
m-C6Hi3Pr2
CH2CMe2Ph
CH2CMe2Ph
CH3
38.70
34.86
s
q
m
d
q
q
s
1JCH 126.8
1JCH 128.8
1JCH 128.4
1JCH 126.3
1JCH 125.0
32.75
28.13
CH2CMe2Ph
CHMe2
CHMe2
23.47
23.13
CHMe2
8a
153.46
153.19
143.36
128.78
ipso-C6Hi3Pr2
ipso-C6H5
o-C6Hi3Pr2
o-C6H5
s
s
dd
2JCH 6.1

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
d
m
t
*
p-C6Hi3Pr2
p-C6H5
*
1JCH 159.2
1JCH 159.7
1JCH 125.9
m-C6H5
m-C6Hi3Pr2
CH2CMe2Ph
CH2CMe2Ph
CH2CMe2Ph
CHMe2
41.09
33.13
s
m
d
q
q
q
dq
s
1JCH 123.6
1JCH 126.2
1JCH 125.9
1JCH 125.8
1JCH 125.8
2JCP 5.2
28.18
24.70
CHMe2
CH3
CHMe2
23.98
23.55
14.74
PMe3
9b
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
CH2CMe2Ph
CH2CMe2Ph
CHMe2
s
s
s
d
d
m
m
t
1JCH 159.9
1JCH 160.1
*
*
1JCH 121.8
39.84
32.18
s
q
d
q
q
q
s
1JCH 126.5
1JCH 127.4
1JCH 125.9
1JCH 125.8
1JCH 125.9
28.28
24.05
CHMe2
CHMe2
23.61
23.23
CHMe2
10a
153.69
153.01
142.52
128.59
ipso-C6Hi3Pr2
ipso-C6H5
o-C6Hi3Pr2
o-C6H5
s
s
dd
1JCH
*
2JCH 7.6
126.40
125.96
d
1JCH 159.9
1JCH 161.2
2JCH 7.6
p-C6Hi3Pr2
p-C6H5
dt
125.49
dt
1JCH 154.3
2JCH 6.9
m-C6H5
122.86
68.54
39.88
m
t
1JCH 156.3
1JCH 124.3
m-C6Hi3Pr2
CH2CMe2Ph
CH2CMe2Ph
CH2CMe2Ph
C HMe2
s
31.83
28.78
q
d
qt
qt
s
1JCH 128.6
1JCH 127.6
1JCH 125.9
1JCH 125.7
23.78
23.51
CHMe2
CHMe2
11b
152.96
152.62
141.59
128.00
126.02
ipso-C6Hi3Pr2
ipso-C6H5
o-C6Hi3Pr2
m-C6H5
s
s
m
dt
1JCH 149.0
1JCH 156.2
2JCH 7.0
p-C6Hi3Pr2
125.25
dt
1JCH 159.9
2JCH 7.3
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
1JCH 159.4
1JCH 156.8
o-C6H5
m-C6Hi3Pr2
NCMe3
t
1JCH 120.9
CH2CMe2Ph
CH2CMe2Ph
NCMe3
s
q
q
d
m
m
1JCH 125.8
1JCH 126.5
1JCH 127.4
1JCH 125.8
1JCH 125.9
CH2CMe2Ph
CHMe2
CHMe2
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)]
(R0 ¼ 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 LiOBut to give the corresponding four-
coordinate species [Mo(OBut)(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(CH2 CMe2Ph)] (8), the NMR data of which
contain a doublet (3JHP 4.5 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 C2 axis
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%.
MoClN2C29H45 requires 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(NBut)(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)(NBut)(CH2CMe2 Ph)]
(3)
As for 1, but using [MoCl2(NAr)(NBut)(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%. MoN2C26H39 requires 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%. MoN2C39H52 requires 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; (FABþ, 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%.
MoClN2C34H47 requires 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%.
MoN2C34H51 requires 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; (FABþ, m/z) 695 [M]þ, 580 [M–
C9H7]þ, 443 [M–C9H7–C6H3i Pr2]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(OBut)(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%. MoN3C46H65 requires 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 LiOBut (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%. MoON2C38H56 re-
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 + OtBu]þ, 654 [M + H]þ,
596 [M–tBu]þ, 580 [M–OtBu]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–CH2Me2 Ph + 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 LiNHBut
Chilled ()78 °C) diethyl ether was added to a solid
mixture of 1 (0.95 g, 1.54 mmol) and LiNHBut (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
Dc (g cmꢂ3
)
1.197
0.41
l (mmꢂ1
)
0.51
19 428
7350
0.40
23 377
8096
0.38
24 256
8790
Data measured
Unique data
Rint
27 405
15 259
0.0168
854
0.0319
374
0.0266
422
0.0203
432
Parameters
R ðF ; F 2 > 2rÞ
Rw ðF 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%.
Mo2ON4C68H94 requires 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 F2 values 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)(NHBut)
(11)
Chilled ()78 °C) diethyl ether was added to a solid
mixture of 1 (0.95 g, 1.55 mmol) and LiNHBut (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
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(b) A.A. Danopoulos, G. Wilkinson, T.K.N. Sweet, M.B. Hurst-
house, Polyhedron 15 (1996) 873;
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(c) V. Saboonchian, A.A. Danopoulos, A. Gutierrez, G. Wilkin-
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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;
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White, D.J. Williams, J. Chem. Soc., Dalton Trans. (2002) 2597.
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2379.
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