Synthesis and reactions of cycloheptadienyl and cyclooctadienyl tungsten complexes: X-ray crystal structure of [W(CO)2 (PPh3)2(η5-C7 H9)][BF4]

Article abstract of DOI:10.1016/j.jorganchem.2003.12.017

Protonation of the cycloheptatriene complex [W(CO)₃ (η⁶-C₇H₈)] with H[BF₄] ·Et₂O in CH₂Cl₂ affords the cycloheptadienyl system [W(CO)₃(η⁵ -C₇H₉)][BF₄] (1). Complex 1 reacts with NaI to yield [WI(CO)₃(η⁵ -C₇H₉)], which is a precursor to [W(CO) ₂(NCMe)₃(η³-C₇ H₉)][BF₄], albeit in very low yield. The dicarbonyl derivatives [W(CO)₂L₂(η⁵ -C₇H₉)]⁺ (L₂ =2PPh₃, 4, or dppm, 5) were obtained, respectively, by H[BF₄]·Et₂O protonation of [W(CO) ₂(PPh₃)(η⁶-C₇ H₈)] in the presence of PPh₃ and reaction of 1 with dppm. The X-ray crystal structure of 4 (as a 1/2 CH₂ Cl₂ solvate) reveals that the two PPh₃ ligands are mutually trans and are located beneath the central dienyl carbon and the centre of the edge bridge. The first examples of cyclooctadienyl tungsten complexes [WBr(CO)₂(NCMe)₂(1-3-η:5, 6-C₈H₁₁)] (6) and [WBr(CO)₂(NCMe) ₂(1-3-η:4,5-C₈H₁₁)] (7) were synthesised by reaction of [W(CO)₃(NCR)₃] (R=Me or Prⁿ) with 3-Br-1,5-cod/6-Br-1,4-cod or 5-Br-1,3-cod/3-Br-1,4-cod (cod=cyclooctadiene), respectively. Complexes 6 and 7 are precursors to the pentahapto-bonded cyclooctadienyl tungsten species [W(CO)₂(dppm)(1-3:5,6-η-C₈ H₁₁)][BF₄] and [W(CO)₂(dppe) (1-5-η-C₈H₁₁)][BF₄]· CH₂Cl₂.

Full text of DOI:10.1016/j.jorganchem.2003.12.017

Journal of Organometallic Chemistry 689 (2004) 848–859
www.elsevier.com/locate/jorganchem
Synthesis and reactions of cycloheptadienyl and
cyclooctadienyl tungsten complexes: X-ray crystal structure
of [W(CO)2(PPh3)2(g5-C7H9)][BF4]
Keith P. Carruthers, Madeleine Helliwell, Jonathan R. Hinchliffe,
*
Ana-Lucia A.B. deSouza, Dale M. Spencer, Mark W. Whiteley
Department of Chemistry, University of Manchester, Manchester M13 9PL, UK
Received 26 September 2003; accepted 1 December 2003
Abstract
Protonation of the cycloheptatriene complex [W(CO)3(g6-C7H8)] with H[BF4] ꢀ Et2O in CH2Cl2 affords the cycloheptadienyl
system [W(CO)3(g5-C7H9)][BF4] (1). Complex 1 reacts with NaI to yield [WI(CO)3(g5-C7H9)], which is a precursor to
[W(CO)2(NCMe)3(g3-C7H9)][BF4], albeit in very low yield. The dicarbonyl derivatives [W(CO)2L2(g5-C7H9)]þ (L2 ¼ 2PPh3, 4, or
dppm, 5) were obtained, respectively, by H[BF4] ꢀ Et2O protonation of [W(CO)2(PPh3)(g6-C7H8)] in the presence of PPh3 and
reaction of 1 with dppm. The X-ray crystal structure of 4 (as a 1/2 CH2Cl2 solvate) reveals that the two PPh3 ligands are mutually
trans and are located beneath the central dienyl carbon and the centre of the edge bridge. The first examples of cyclooctadienyl
tungsten complexes [WBr(CO)2(NCMe)2(1–3-g:5,6-C8H11)] (6) and [WBr(CO)2(NCMe)2(1–3-g:4,5-C8H11)] (7) were synthesised by
reaction of [W(CO)3(NCR)3] (R ¼ Me or Prn) with 3-Br-1,5-cod/6-Br-1,4-cod or 5-Br-1,3-cod/3-Br-1,4-cod (cod ¼ cyclooctadiene),
respectively. Complexes 6 and 7 are precursors to the pentahapto-bonded cyclooctadienyl tungsten species [W(CO)2(dppm)(1–3:5,6-
g-C8H11)][BF4] and [W(CO)2(dppe)(1–5-g-C8H11)][BF4] ꢀ CH2Cl2.
Ó 2004 Elsevier B.V. All rights reserved.
Keywords: Dienyl; Tungsten; Cycloheptadienyl; Cyclooctadienyl; Edge bridge
1. Introduction
we extend our investigations to the chemistry of the
analogous tungsten systems. It is not our intention to
provide a comprehensive and exhaustive account of
cycloheptadienyl and cyclooctadienyl tungsten chemistry
but rather our objectives are (i) to describe synthetic
routes to the tungsten complexes and (ii) to highlight
differences in reactivity resulting from exchange of
molybdenum for tungsten especially with respect to
g5 ! g3 hapticity conversion processes. In addition to
our preliminary account of this work [7], some aspects of
cycloheptadienyl tungsten chemistry have been devel-
oped previously. These comprise the synthesis of the mon
osubstituted, pentahapto-cycloheptadienyl complexes
(i) [W(CO)3L(g5-C7H9)]þ (L ¼ P-, As- or Sb-donor
ligand) via reaction of L with [W(CO)3(g5-C7H9)]þ [8]
and (ii) [WX(CO)3(g5-C7H9)] (X ¼ Me [9] or SnPh3 [10])
derived from the anion [W(CO)3(g5-C7H9)]ꢁ. One case
of the C7H9 ligand-bonded trihapto to tungsten,
The cyclohexadienyl (C6H7), cycloheptadienyl (C7H9)
and cyclooctadienyl (C8H11) ligands constitute a sub-
class of dienyl ligands in which the terminal dienyl car-
bons are linked by an edge bridge consisting of one, two
or three methylene groups, respectively. Edge-bridged
dienyl ligands are of interest because of the structural
effects of the edge bridge and their ability to coordinate
to a metal centre both as g5 and g3 ligands with inter-
conversion between the two hapticity types in selected
examples [1,2]. The focus of our work in this area to date
has been with cycloheptadienyl [3,4] and cyclooctadienyl
[5,6] complexes of molybdenum but in the current paper
* Corresponding author. Tel.: +44-161-275-4634; fax: +44-161-275-
4598.
E-mail address: mark.whiteley@man.ac.uk (M.W. Whiteley).
0022-328X/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2003.12.017

K.P. Carruthers et al. / Journal of Organometallic Chemistry 689 (2004) 848–859
849
[W(CO)2(g3-C7H9)(g-C5H4Me)], has also been reported
[11]. The cyclooctadienyl tungsten complexes described
here represent the first examples of this system.
availability of [Mo(CO)2(NCMe)3(g3-C7H9)]þ which is
a versatile precursor to a wide range of derivatives
[Mo(CO)2L2(g5-C7H9)]þ (L2 ¼ 2 PR3, Ph2P(CH2)nPPh2
(n ¼ 1, dppm, n ¼ 2, dppe), 2,20 -bipyridine, diene, etc.)
[3]. The synthesis of [Mo(CO)2(NCMe)3(g3-C7H9)]þ
was effected in a two-step process involving protonation
of [Mo(CO)3(g6-C7H8)] with H[BF4] ꢀ Et2O in CO sat-
urated CH2Cl2 to give [Mo(CO)4(g5-C7H9)]þ followed
by reaction with NCMe to yield [Mo(CO)2(NCMe)3(g3-
C7H9)]þ. The initial strategy in the current investigation
was therefore to synthesise [W(CO)2(NCMe)3(g3-
C7H9)]þ starting from [W(CO)3(g6-C7H8)] and to apply
this as a precursor to a range of novel dicarbonyl cy-
cloheptadienyl tungsten complexes of the type [W(CO)2
L2(g5-C7H9)]þ. As discussed in Section 1, previously
reported examples of cycloheptadienyl tungsten com-
plexes are limited to tricarbonyl derivatives of the
type [W(CO)3L(g5-C7H9)]þ and [WX(CO)3(g5-C7H9)]
[8–10].
2. Results and discussion
2.1. Cycloheptadienyl complexes
Our investigations on the chemistry of the cyclohep-
tadienyl tungsten system are summarised in Scheme 1.
Microanalytical, infrared and mass spectroscopic data
for each of the complexes are presented in Table 1 and
1H, 13C{1H} and 31P{1H} NMR data are given in
Table 2. A full account of the spectroscopic data for
analogous molybdenum complexes has been presented
previously [3,4] and therefore discussion here is re-
stricted to specific, salient points.
Progress in the development of cycloheptadienyl
molybdenum chemistry has been facilitated by the
Treatment of a CO saturated, CH2Cl2 solution of
[W(CO)3(g6-C7H8)] with H[BF4] ꢀ Et2O at 0 °C followed
by slow warming to ambient temperature afforded an
orange-yellow solution. In contrast to the molybdenum
system, no precipitate formed directly from the reaction
mixture but subsequent work up led to isolation of the
product as an orange oil or, on occasions, as an orange
solid. Infrared spectroscopic data indicated that the
isolated material was not [W(CO)4(g5-C7H9)][BF4] but
the formally 16-electron, tricarbonyl species [W(CO)3
(g5-C7H9)][BF4] (1). Thus, the CH2Cl2 solution infrared
spectrum of 1 has two strong bands (m(CO) (cmꢁ1) 2058,
1980), in contrast to the three band spectrum of
[Mo(CO)4(g-C7H9)][BF4] (m(CO), CH2Cl2 (cmꢁ1), 2112,
2065, 2008), but comparable with related cyclopenta-
dienyl complexes [M(CO)3(g-C5H5)][BF4] (m(CO),
CH2Cl2 (cmꢁ1), M ¼ Mo, 2071, 1988; M ¼ W, 2067,
1975) [12], which also possess formal 16-electron con-
figurations although it has been suggested that these
latter complexes incorporate an F-coordinated BF4 li-
gand. In fact the tricarbonyl cycloheptadienyl complexes
[M(CO)3(g5-C7H9)][BF4] (M ¼ Mo [13] or W [8]) have
been prepared previously by protonation of [M(CO)3
(g6-C7H8)] in propionic anhydride but the tungsten
derivative could not be isolated free from solvent resi-
dues. The modified synthesis described here led to iso-
lation of solvent free [W(CO)3(g5-C7H9)][BF4] and this
allowed us to confirm its identity by microanalysis and
1H NMR spectroscopy. It is probable that in our pre-
vious work, the tetracarbonyl [Mo(CO)4(g5-C7H9)]
[BF4] was generated by in situ carbonylation of [Mo
(CO)3(g5-C7H9)][BF4] so paralleling the reactions of the
cyclopentadienyl complexes [M(CO)3(g-C5H5)][BF4]
(M ¼ Mo or W) with carbon monoxide to yield [M(CO)4
(g-C5H5)][BF4] [12]. However, [W(CO)3(g5-C7H9)]
[BF4] appears to be unreactive towards addition of CO
and complex 1 was isolated independent of whether
Scheme 1. Reagents and conditions: (i) L ¼ CO; H[BF4] ꢀ Et2O in
CH2Cl2, 30 min. (ii) NaI in acetone, )78 °C, 1 h. (iii) Ag[BF4] in
NCMe, 30 min. (iv) L ¼ PPh3; H[BF4] ꢀ Et2O/PPh3 in THF, 1 h. (v) (a)
dppm in CH2Cl2, 1 h. (b) Reflux in 2-butanone, 30 min.

Table 1
Microanalytical, infrared and mass spectroscopic data
Complex
Analysis (%)a
C
Infraredb
m(CO) (cmꢁ1
Mass spectral datac
)
H
N
1 [W(CO)3(g5-C7H9)][BF4]
2 [WI(CO)3(g5-C7H9)]
27.1 (26.8)
2.3 (2.0)
2058, 1980
2035, 1959
24.7 (24.6)
2.0d (1.8)
488 (MþÞ, 460 ([M ) CO]þ), 432 ([M ) 2CO]þ),
404 ([M ) 3CO]þ), 363 ([M ) I]þ)
3 [W(CO)2(NCMe)3(g3-C7H9)][BF4]
32.9 (33.2)
3.3 (3.3)
7.8 (7.7)
1952, 1869e
415 ([M ) NCMe]þ), 374 ([M ) 2NCMe]þ),
318 ([M ) 2NCMe ) 2CO]þ)
4 [W(CO)2(PPh3)2(g5-C7H9)][BF4]
5 [W(CO)2(dppm)(g5-C7H9)][BF4]
6 [WBr(CO)2(NCMe)2(1–3-g:5,6-C8H11)]
57.3 (57.2)
50.5 (50.8)
33.4 (33.0)
4.3 (4.1)
4.1 (3.9)
3.5 (3.4)
1974, 1898
2013, 1919
1936, 1847e
857 (MþÞ, 595 ([M ) PPh3]þ)f
717 (MþÞ, 687 ([M ) CO ) 2H]þ), 659 ([M ) 2CO ) 2H]þ)
5.7 (5.5)
5.7 (5.5)
469 ([M ) NCMe]þ), 428 ([M ) 2NCMe]þ or [M ) Br]þ,
400 ([M ) 2NCMe ) CO]þ), 388 ([M ) NCMe ) Br]þ)
7 [WBr(CO)2(NCMe)2(1–3-g:4,5-C8H11)]
8 [WBr(CO)2(dppm)(1–3-g:5,6-C8H11)]
33.3 (33.0)
51.5 (51.8)
3.6 (3.4)
4.1 (4.1)
1937, 1848e
1932, 1843
469 ([M ) NCMe]þ), 428 ([M ) 2NCMe]þ or [M ) Br]þ,
400 ([M ) 2NCMe ) CO]þ), 388 ([M ) NCMe ) Br]þ)
812 (MþÞ, 784 ([M ) CO]þ), 754 ([M ) 2CO ) 2H]þ),
731 ([M ) Br]þ), 703 ([M ) Br ) CO]þ),
676 ([M ) Br ) 2CO]þ), 647 ([M ) 2CO ) C8H11]þ)
9 [W(CO)2(dppm)(1–3:5,6-g-C8H11)][BF4]
51.7 (51.4)
51.8 (51.7)
4.2 (4.1)
4.3 (4.2)
1995, 1891
1951, 1862e
731 (MþÞ, 701 ([M ) CO ) 2H]þ), 673 ([M ) 2CO ) 2H]þ)
10 [W(CO)2(NCMe)(dppm)(1–3-g:5,6-C8H11)][BF4]
1.6 (1.6)
772 (MþÞ, 731 ([M ) NCMe]þ) 701
([M ) NCMe ) CO ) 2H]þ), 673 ([M ) NCMe ) 2CO ) 2H]þ)
11 [WBr(CO)2(dppe)(1–3-g:4,5-C8H11)]
51.9 (52.4)
48.5 (48.4)
4.3 (4.2)
1926, 1833
1991, 1916
824 (MþÞ, 768 ([M ) 2CO]þ), 745 ([M ) Br]þ),
716 ([M ) Br ) CO]þ), 660 ([M ) 2CO ) C8H11]þ)
12 [W(CO)2(dppe)(1–5-g-C8H11)][BF4] ꢀ CH2Cl2
3.9g (4.0)
745 (MþÞ, 715 ([M ) CO ) 2H]þ), 685 ([M ) 2CO ) 4H]þ)
a Calculated values in parentheses.
b Solution spectra in CH2Cl2 unless stated otherwise.
c FAB mass spectra unless stated otherwise, m=z values based on 184W.
d I, 26.9 (26.0).
e In CH3CN.
f Electrospray mass spectrum in NCMe.
g Cl 6.8 (7.7).

Table 2
1H, 13C{1H} and 31P{1H} NMR dataa;b
1H NMR
13C{1H} NMR
CO
Hdienyl
Hmethylene
L
Cdienyl
Cmethylene
L
1c
6.40, 1H, m, H5; 6.02,
2H, m, H4;6; 5.58, 2H,
d, H3;7 J(H3=7–H4=6) 8
2.50, 4H, br, H1;2
2de
5.78, 1H, br, H5; 5.31,
2H, m, H4;6; 4.88, 2H,
d, H3;7 J(H3=7–H4=6) 9
2.62, 4H, br, H1;2
215.5, 202.9
214.6, 213.0
101.1, 91.7, 88.5
131.3, 128.2, C6;7
33.5
3ef
6.21, 1H, dd, H6, J(H5– 2.65, 1H, m, H2;
;
30.0, 27.8
H6) 7, J(H6–H7) 11;
5.26, 1H, m, H7, 4.69,
1H, m, 4.66, 1H, m, H3
and H5; 3.61, 1H, at,
H4, J(H4–H3=5) 8
2.11, 2H, m, H1 and
H2; 1.40, 1H, m, H1
70.6, 69.4, 68.4, C3;4;5
4
5.34, 3H, m, H4;5;6
4.62, 2H, br, H3;7
;
1.90, 2H, m, 1.17,
2H, m, H1;2
7.54, 7.48, 30H, m,
Ph (PPh3)
220.9, t, J(P–C) 19
102.6, 101.0, 91.5
34.2
133.7, 132.1,
129.4 (PPh3)
5g
6.15, 1H, 5.35, 1H,
2.45, 1H, m, 2.33,
7.86–7.06, 6.62, 20H,
m, Ph(dppm)
5.23, 1H, 5.12 1H, 4.58, 1H, m, 2,12, 1H, m,
1H, 4.33, 1H, 4.17, 1H, 2.08, 1H, m, H1;2
H3–7 and dppm CH2
6f
5.86, 1H, m, H5; 5.51,
2.50, 1H, m, H4;
218.4, 218.2
130.7, 130.4, C5;6
65.4, 65.1, 64.3 C1;2;3
;
33.6, 32.4, C4;7;8
1H, m, H6, 4.24, 1H, m, 2.39–2.03, 4H, m,
4.05, 1H, m, H1 and
H3; 3.22, 1H, at, H2,
J(H2–H1=3) 8
H4;7;8; 1.76, 1H, m,
H8
7f
6.28, 1H, dd, H4, J(H4– 2.97, 1H, m, 1H, H6;
Not observed
136.5, 126.2, C5;6
66.2, 59.9, 59.5, C1;2;3
;
33.2, 31.5, 25.4, C6;7;8
H5) 10; 5.22, 1H, m,
H5, 4.31, 1H, br, 3.69,
1H, m, H1 and H3;
3.56, 1H, at, H2,
J(H2–H1=3) 7
2.10, 2H, m, H6;8
;
1.65, 1H, m, 1.28, 1H,
m, H7; 0.90, 1H,
m, H8
8
5.83, 1H, m, H5; 5.49,
1H, m, H6, 4.82, 1H,
2.59, 1H, m, H4;
7.58–7.29, 20H, m,
Ph; 4.87, 1H, m,
4.51, 1H, m,
219.1, m; 218.4, m
74.7, C2h
33.5, 31.6
133.7–128.9, Ph;
37.2, t, J(C–P) 24,
CH2(dppm)
2.51, 2H, m, H4 and
br, 4.67, 1H, br, H1 and H8; 2.27, 2H, m, H7;
H3; 3.29, 1H, m, H2
2.10, 1H, m, H8
CH2(dppm)
9i
5.26, 1H, at, H2,
3.76, 1H, m, H4;
2.68, 3H, m, H7,
H8; 2.38, 1H, m,
H4; 2.27, 1H, m, H8
7.76–7.24, 20H, m,
Ph; 5.64, 1H, m;
4.53, 1H, m,
219.7, dd, J(C–P) 22,
5; 209.4, dd, J(C–P)
10, 3
111.4, C6; 104.9, C2;
71.4, C1; 63.9, C3;
57.2, C5
32.8, C7; 29.4, C8;
21.8, C4
134.3–129.2, Ph;
43.9, t, J(P–C) 29,
CH2(dppm)
J(H2–H1=3) 8; 5.13,
1H, m, H1; 4.82, 1H,
m, H6; 4.69, 1H, m,
H3, 2.98, 1H, m, H5
CH2(dppm)

Table 2 (continued)
1H NMR
13C{1H} NMR
CO
Hdienyl
Hmethylene
L
Cdienyl
Cmethylene
L
10f ;g;j
5.82, 1H, br, H5;
5.55, 1H, m, H6,
4.95, 1H, br, 4.57,
1H, br, H1 and H3;
4.19, 1H, br, H2
2.68–2.15, 6H, br,
H4, H7, H8
7.94–7.51, 20H, m,
Ph; 5.09, m, 1H,
4.76, 1H, m,
216.9, m; 211.9, m
84.2, 82.7, 67.8 82.5ꢂ,
79.8ꢂ, 68.8ꢂj
32.4, 30.8, 29.6
132.5–125.5, Ph;
37.0, t, J(C–P) 26,
CH2(dppm)
CH2(dppm)
11
6.25, 1H, dd, H4,
J(H4–H5) 11; 5.24,
1H, m, H5, 4.90, 1H,
br, H3; 4.18, 1H, br,
H1; 3.50, 1H, at, H2,
J(H2–H1=3) 8
2.79, 1H, m, 2.03,
1H, m, H6; 2.25, m,
1H, H8; 1.54, 1H,
H7, 1.23, 2H, m, H7,
H8
7.72–7.44, 20H, m,
Ph; 3.07, m, 2H,
CH2, 2.41, m, 2H,
CH2(dppe)
218.1, at, J(C–P) 11
215.1 at, J(C–P) 7
76.4, 66.3, 64.6, C1,
C2, C3k
31.3, 29.4, 24.5
134.4–126.4, Ph,
26.7, m, CH2(dppe)
12g
5.44, 1H, m, H3;
2.57, 1H, m, 2.29,
1H, br, 1.60, 2H, br,
H6, H8; 1.18, 1H, br,
0.38, 1H, m, H7
7.62–7.04, Ph; 2.96,
1H, m, 2.63, 3H, m,
CH2(dppe)
220.4, 210.6
106.8, C3; 88.5, br,
86.3, br, 84.5, br,
59.2, br, C1;2;4;5
27.9, br, 25.5,
br, C6;8; 18.8, C7
133.0–129.6, Ph;
29.5, m, CH2(dppe)
5.35, 1H, br, 4.43,
1H, br, 4.33, 1H, br,
3.73, 1H, br, H1;2;4;5
d, doublet; t, triplet; at, apparent triplet; m, multiplet; br, broad; chemical shifts downfield from SiMe4, coupling constants in hertz; in CD2Cl2 solution unless stated otherwise, numbering as in
Schemes 1 and 2. All spectra recorded at room temperature unless stated otherwise.
a 300 MHz 1H, 75 MHz 13C{1H}, 121.5 MHz 31P{1H} NMR spectra unless stated otherwise.
b
31P{1H} NMR data: 4, (25 °C) 18.3; ()50 °C) 20.9, d, J(P–P) 18, J(183W–P) 169, 16.5, d, J(P–P) 18, J(183W–P) 223; 5, (25 °C) )31.7, br; ()70 °C) AB doublet of doublets, )32.3, d, J(P–P) 63;
)33.2, d, J(P–P) 63; 8, (30 °C) )21.5, br; ()80 °C) isomer 1: )7.1, d, J(P–P) 25, J(183W–P) 189, )30.1, d, J(P–P) 25, J(183W–P) 145; isomer 2: )8.1, d, J(P–P) 23, J(183W–P) 188; )30.7, d, J(P–P) 23,
J(183W–P) 146; (approximate ratio, isomer 1 to isomer 2, 2:1). 9, )35.2, d, J(P–P) 49, J(183W–P) 201; )36.5, d, J(P–P) 49, J(183W–P) 187; 12, ()30 °C), 43.8, d, J(P–P) 23, J(183W–P) 263; 35.2, d,
J(P–P) 22, J(183W–P) 183, J(P–P) not resolved at room temperature.
c In acetone-D-6.
d In CDCl3.
e Assignments with the aid of 1H-1H decoupling experiments.
f In CD3CN.
g Low temperature spectra, 5: 1H ()70 °C); 10: 13C ()30 °C); 12: 1H ()30 °C).
h C5;6 obscurred by dppm Ph carbons, C1;3 not observed.
i 500 MHz 1H, 125 MHz 13C{1H} NMR spectra, assignments made with the aid of standard 2D techniques.
j Resonances for minor isomer marked with asterisk.
k C4;5 obscurred by dppe Ph carbons.

K.P. Carruthers et al. / Journal of Organometallic Chemistry 689 (2004) 848–859
853
protonation of [W(CO)3(g6-C7H8)] was carried out
under a CO or nitrogen atmosphere.
The second step of the synthesis of [W(CO)2
(NCMe)3(g3-C7H9)][BF4] (3) was attempted by disso-
lution of [W(CO)3(g5-C7H9)][BF4] in stirred NCMe.
Work up of the reaction mixture gave an orange solid
with infrared active carbonyl stretching frequencies
(m(CO), CH3CN (cmꢁ1) 1952, 1869) consistent with the
formation of 3 (cf. [Mo(CO)2(NCMe)3(g3-C7H9)][BF4]
(m(CO), CH3CN (cmꢁ1) 1958, 1877) [3]. However, at-
tempts to generate a pure form of this material were
unsuccessful and ultimately complex 3 was obtained in a
two step synthesis from 1. First, reaction of [W
(CO)3(g5-C7H9)][BF4] with excess NaI in acetone at
)78 °C afforded [WI(CO)3(g5-C7H9)] (2). Subsequent
reaction of complex 2 with Ag[BF4] in NCMe resulted in
iodide abstraction and formation of low yields of an
analytically pure sample of 3. Complex 3 is a rare ex-
ample of the cycloheptadienyl ligand-bonded trihapto to
tungsten; its identity as an g3-C7H9 complex was es-
tablished conclusively by the 13C{1H} NMR data which
reveal characteristic shifts for the olefin (C(6), C(7)) and
allyl (C(3)–C(5)) carbons.
Although a synthesis of [W(CO)2(NCMe)3(g3-C7H9)]
[BF4] (3) was developed, the overall yield from
[W(CO)3(g6-C7H8)] was too low for 3 to be an effective
precursor to further cycloheptadienyl tungsten com-
plexes. Two alternative synthetic routes to dicarbonyl
complexes [W(CO)2L2(g5-C7H9)]þ were therefore ex-
plored. First, the protonation of substituted cyclohept-
atriene complexes [W(CO)2L(g6-C7H8)] (L ¼ P-donor
ligand) in the presence of L was investigated. [W(CO)2
(PPh3)(g6-C7H8)] was prepared by reaction of [W(CO)2
(PPh3)(g-C7H7)][BF4] [14,15] with Na[BH4] in THF.
Subsequent protonation with H[BF4] ꢀ Et2O in THF in
the presence of PPh3 afforded [W(CO)2 (PPh3)2(g5-
C7H9)][BF4] (4) which precipitated from the reaction
mixture as a bright yellow solid. Complex 4 is the first
example of the general formulation [W(CO)2L2(g5-
C7H9)]þ and is reported not to be accessible by direct
reaction of PPh3 with substitution inert [W(CO)3(PPh3)
(g5-C7H9)][BF4] [8].
Fig. 1. (a,b) Structure types of [M(L)2(PR3)2(g5-dienyl)]nþ (dienyl ¼
‘‘open’’ or edge-bridged ligand).
logues [Re(H)2(PMe2Ph)2(g5-dienyl)] are found to have
structure (b) [17,18]. It might be speculated that the edge
bridge in 4 could also promote the adoption of structure
(b) – to our knowledge there are no crystallographically
characterised examples of [M(CO)2(PR3)2(g5-dienyl)]nþ
incorporating an edge-bridged dienyl ligand. Infrared
data for 4 were consistent with a trans arrangement of
the carbonyl ligands and this observation encouraged
more detailed structural studies.
A spectroscopic handle on this problem is to employ
variable temperature 31P{1H} NMR methods [19]. At
ambient temperature only a singlet resonance was ap-
parent in the 31P{1H} NMR spectrum of 4 but at )50 °C,
a clearly resolved doublet of doublets pattern with as-
sociated 183W satellites was observed. The implication
that structure (a), with inequivalent 31P environments, is
adopted was confirmed by an X-ray crystallographic
study. The X-ray crystal structure of [W(CO)2(PPh3)2
(g5-C7H9)][BF4] ꢀ 0.5CH2Cl2, and the crystallographic
numbering scheme are presented in Fig. 2 and important
bond lengths and angles are given in Table 3. It is clear
that 4 adopts structure type (a) with P(1) located beneath
the edge-bridge carbons C(4) and C(5) (crystallographic
numbering scheme) and P(2) placed under the central
dienyl carbon C(1). The structure was examined for
unusual features or distortions resulting from accom-
modation of P(1) under the edge bridge. One response of
The structure of complex 4 is of particular interest
with regard to the orientation of the W(CO)2(PPh3)2
unit with respect to the edge bridge of the dienyl ligand.
In the solid state, dienyl complexes of the type [M(L)2
(PR3)2(g5-dienyl)]nþ (dienyl ¼ acyclic or edge-bridged
ligand) exhibit two alternative arrangements of the
M(L)2(PR3)2 unit with respect to the dienyl ligand –
Figs. 1(a) and (b). Structure type (a) is adopted by all
complexes in which the dienyl ligand is an ‘‘open’’ acy-
clic pentadienyl ligand of the type C5H7 (pentadienyl) or
2,4-Me2-pentadienyl. However, whilst the ‘‘open’’ pen-
tadienyl system [Re(H)2(PMe2Ph)2(g5-2,4-Me2-penta-
dienyl)] assumes structure (a) in the solid state [16], the
edge-bridged cyclohexadienyl and cyclooctadienyl ana-
Fig. 2. Molecular structure of complex 4; BF4 counter anion and
CH2Cl2 omitted.

854
K.P. Carruthers et al. / Journal of Organometallic Chemistry 689 (2004) 848–859
Table 3
ꢀ
Important bond lengths (A) and angles (°) for complex 4
W(1)–P(1)
W(1)–P(2)
W(1)–C(1)
W(1)–C(2)
W(1)–C(3)
W(1)–C(6)
W(1)–C(7)
W(1)–C(44)
W(1)–C(45)
2.568(3)
2.522(3)
C(44)–O(1)
C(45)–O(2)
C(1)–C(2)
C(2)–C(3)
C(3)–C(4)
C(4)–C(5)
C(5)–C(6)
C(6)–C(7)
C(7)–C(1)
1.131(13)
1.135(12)
1.422(17)
1.358(16)
1.448(17)
1.542(19)
1.516(17)
1.387(16)
1.403(17)
2.334(12)
2.350(12)
2.399(13)
2.371(11)
2.339(11)
1.994(14)
1.984(12)
P(1)–W(1)–P(2)
C(44)–W(1)–C(45)
P(1)–W(1)–C(44)
P(1)–W(1)–C(45)
P(2)–W(1)–C(44)
P(2)–W(1)–C(45)
W(1)–C(44)–O(1)
W(1)–C(45)–O(2)
136.46(9)
C(1)–C(2)–C(3)
C(2)–C(3)–C(4)
C(3)–C(4)–C(5)
C(4)–C(5)–C(6)
C(5)–C(6)–C(7)
C(6)–C(7)–C(1)
C(7)–C(1)–C(2)
128.1(13)
128.4(13)
115.5(11)
111.3(11)
122.5(12)
121.1(11)
123.5(12)
106.4(5)
79.0(3)
74.8(3)
79.8(3)
75.4(3)
179.3(11)
178.5(11)
the cycloheptadienyl ligand could be to bend the edge
bridge C(4)–C(5) away from P(1) and the associated
phenyl groups by increasing the fold angle a between the
best planes defined by [C(3)–C(4)–C(5)–C(6)] and [C(3)–
C(2)–C(1)–C(7)–C(6)]. For 4, the fold angle a is esti-
mated as 135.3° (measured on the face of the ligand re-
mote from the metal centre). The equivalent angle in
[Mo(CO)2(dppm)(g5-C7H9)][BF4], in which a carbonyl
ligand is located beneath the edge bridge is 133.4°, in-
dicating no significant effect on this parameter. An al-
ternative response could be manifest in distortion of the
W(CO)2(PPh3)2 unit through elongation of W–P bond
lengths or a decrease in the P(1)–W(1)–P(2) angle.
However, yet again no unusual parameters were ob-
served. The W–P bond lengths in 4 (W(1)–P(1) 2.568(3)
To complete our investigations on the cyclohepta-
dienyl tungsten system, the synthesis of the chelate
phosphine derivatives [W(CO)2(P-P)(g5-C7H9)]þ (P-
P ¼ dppm or dppe) was explored. The initial synthetic
approach, which attempted to employ 0cycloheptatriene
complexes of the type [W(CO)2(P-P )(g6-C7H8)] (P-
P0 ¼ pendant dppm or dppe) in a synthesis analogous to
that of complex 4 was unproductive. The alternative,
successful strategy is based on the direct reaction of
[W(CO)3(g5-C7H9)][BF4] with phosphines L, which is
reported to give [W(CO)3L(g5-C7H9)][BF4] (with the
exception of the bidentate phosphine, dppe, for which a
ligand-bridged product, [{W(CO)3(g5-C7H9)}2(l-dppe)]
[BF4]2 is obtained) [8]. When a CH2Cl2 solution of
[W(CO)3(g5-C7H9)][BF4], generated in situ from
[W(CO)3(g6-C7H8)] and H[BF4] ꢀ Et2O, was treated with
dppm, a product tentatively formulated as the pendant
phosphine complex [W(CO)3(dppm-P0 )(g5- C7H9)][BF4]
was obtained (m(CO) CH2Cl2, cmꢁ1, 2041, 1978, 1938).
Subsequent reflux of this intermediate in butanone re-
sulted in chelation of the dppm ligand and formation of
[W(CO)2(dppm)(g5-C7H9)][BF4], 5, which was isolated
as an orange solid following purification by column
chromatography on silica. Spectroscopic data for 5 are
similar to the molybdenum analogue including the re-
quirement to acquire NMR spectroscopic data at low
temperature to obtain well resolved spectra.
ꢀ
ꢀ
A; W(1)–P(2) 2.552(3) A) lie within a range of W–P
ꢀ
distances reported for [WBr2(CO)2(PPh3)2] (2.481(9) A;
ꢀ
2.486(9) A) [20] and [NEt4][WCl2(CO)2(PPh3)(g-C3H5)]
ꢀ
(2.581(3) A) [21]. Moreover, the geometry of the
W(CO)2(PPh3)2 as defined by the angles P(1)–W–P(2)
(b ¼ 136:46ð9Þ°) and C(44)–W(1)–C(45) (c ¼ 106:4ð5Þ°)
is remarkably similar to the geometry of the Nb(CO)2
(PMe2Ph)2 unit in [Nb(CO)2(PMe2Ph)2(g5-2,4-Me2-
pentadienyl)] for which the corresponding angles are:
b ¼ 135:5ð1Þ°, c ¼ 107:0ð2Þ° [19]. There is, however,
some difference in the barrier to dienyl rotation for
[Nb(CO)2(PMe2Ph)2(g5-2,4-Me2-pentadienyl)]
and
complex 4. Variable temperature 31P{1H} NMR studies
on 4 reveal a coalescence temperature for the two
phosphorus environments of 260 K leading to an esti-
Complex 5 is of particular interest for potential
g5 ! g3 hapticity conversion at the cycloheptadienyl
ligand. In the case of the analogous molybdenum com-
plexes [Mo(CO)2{Ph2P(CH2)nPPh2}(g5-C7H9)]þ, the
dppe derivative dissolves in NCMe to give an equilib-
rium mixture of the ring slipped, trihapto-bonded
cycloheptadienyl complex [Mo(CO)2(NCMe)(dppe)(g3-
C7H9)]þ and starting material. By contrast the dppm
derivative remains unchanged as [Mo(CO)2(dppm)(g5-
C7H9)]þ when dissolved in NCMe [4]. It has been shown
mate of DGz for dienyl rotation as 48.1 ꢃ 1 kJ molꢁ1
.
This is higher than the value of DGz ¼ 43:9 ꢃ 1 kJ molꢁ1
calculated [19] for the equivalent process in
[Nb(CO)2(PMe2Ph)2(g5-2,4-Me2-pentadienyl)] although
clearly the different identities of M(CO)2(PR3)2 units
preclude a direct comparison of the effect of the dienyl
ligand.

K.P. Carruthers et al. / Journal of Organometallic Chemistry 689 (2004) 848–859
855
that hapticity conversions in cycloheptatrienyl com-
plexes, driven by addition of NCMe at the metal centre,
are facilitated by exchange of Mo for W [22]. However,
when 5 was dissolved in NCMe, there was no spectro-
scopic evidence for the formation of the ring slipped
acetonitrile adduct [W(CO)2(NCMe)(dppm)(g3-C7H9)]
[BF4]. We conclude, therefore, that exchange of Mo for
W has a relatively small effect on the preferred hapticity
of the cycloheptadienyl ligand and, in this example, the
g5 bonding mode is retained for both Mo and W.
2.2. Cyclooctadienyl complexes
Our investigations on the chemistry of the cyclooc-
tadienyl tungsten system are summarised in Scheme 2(a)
and (b). Microanalytical, infrared and mass spectro-
scopic data for each of the complexes are presented in
1
Table 1, and H, 13C{1H} and 31P{1H} NMR data are
given in Table 2. Again, a full account of the spectro-
scopic data for analogous molybdenum complexes has
been presented previously [5,6] and, therefore, further
discussion here is restricted. Both commonly observed
forms of the cyclooctadienyl ligand are included in this
study. In the first case (1–5-g-C8H11) all three methy-
lene carbons are adjacent and these bridge the terminal
dienyl carbons but in the second isomeric form
(1–3:5,6-g-C8H11) one methylene group is located
between isolated allyl and olefin components of the
‘‘dienyl’’ unit.
The synthetic route that we developed to cycloocta-
dienyl molybdenum complexes [5] is closely paralleled in
the corresponding tungsten chemistry. Thus reaction of
acetonitrile solutions of [W(CO)3(NCR)3] (R ¼ Me or
Prn) with mixtures of either 3-Br-1,5-cod/6-Br-1,4-cod or
5-Br-1,3-cod/3-Br-1,4-cod (cod ¼ cyclooctadiene) led,
respectively, to the formation and precipitation of [WBr
(CO)2(NCMe)2(1–3-g:5,6-C8H11)] (6) and [WBr (CO)2
(NCMe)2(1–3-g:4,5-C8H11)] (7). As in the analogous
chemistry of molybdenum, complexes 6 and 7 are po-
tential precursors to an extensive chemistry of the cy-
clooctadienyl tungsten system. However, our studies
focus on two investigations which explore possible
modifications in reactivity imposed by the exchange of
molybdenum for tungsten.
We have previously described the synthesis and re-
activity of three pentahapto-bonded cyclooctadienyl
molybdenum complexes [Mo(CO)2(P-P)(g5-C8H11)]þ
(g5-C8H11 ¼ 1–3:5,6-g-C8H11, P-P ¼ dppe or dppm; g5-
C8H11 ¼ 1–5-g-C8H11, P-P ¼ dppm) [6]. The fourth
combination (g5-C8H11 ¼ 1–5-g-C8H11, P-P ¼ dppe)
was not accessible; attempts to generate this complex led
instead to isolation of [Mo(CO)3(dppe)(1–3-g:4,5-
C8H11)]þ probably via partial decomposition of [Mo
(CO)2(dppe)(g5-1–5-C8H11)]þ and CO exchange. We
have also described the reactions of these complexes
with 2-electron donor ligands L0 such as NCMe or CO
Scheme 2. (a) Reagents and conditions: (i) dppm in CH2Cl2, 20 min;
(ii) Ag[BF4] in CH2Cl2, 112 h; (iii) Stir in NCMe, 2 h; (iv) Stir in
CH2Cl2, 18 h. (b) Reagents and conditions: (i) dppe in CH2Cl2, 112 h;
(ii) Ag[BF4] in CH2Cl2, 1 h.
leading to adducts of the type [Mo(CO)2L0 (P-P)(g3-
C8H11)]þ with accompanying g5 ! g3 hapticity con-
version at the cyclooctadienyl ring [6]. However, this
reactivity is moderated both by the identity of the
cyclooctadienyl ligand and the supporting phosphine
ligand with the combination g5-C8H11 ¼ 1–3:5,6-g-
C8H11, P-P ¼ dppm, least reactive towards addition of
L0 . These observations suggested two objectives for our
work with the cyclooctadienyl tungsten system: (i) an
investigation of the synthesis of [W(CO)2(dppm)(1–
3:5,6-g-C8H11)]þ and the stability of its ligand adducts
[W(CO)2L0 (dppm)(1–3-g:5,6-C8H11)]þ and (ii) the
synthesis of [W(CO)2(dppe)(1–5-g-C8H11)]þ, a complex
which has no direct analogue in molybdenum chemistry.

856
K.P. Carruthers et al. / Journal of Organometallic Chemistry 689 (2004) 848–859
Reaction of [WBr(CO)2(NCMe)2(1–3-g:5,6-C8H11)]
3. Conclusions
(6) with dppm in CH2Cl2 affords [WBr(CO)2(dppm)(1–
3-g:5,6-C8H11)] (8), which is a precursor to [W(CO)2
(dppm)(1–3:5,6-g-C8H11)][BF4] (9) by treatment with
Ag[BF4] in CH2Cl2. Complex 9, which was isolated as
an orange-pink solid, is a unique example of the 1–
3:5,6-g-C8H11 ligand co-ordinated to tungsten. When 9
was dissolved in NCMe, the ligand adduct [W
(CO)2(NCMe)(dppm)(1–3-g:5,6-C8H11)][BF4] (10) was
fully formed and isolable as a stable yellow solid. The
purpose of the synthesis of 10 was to establish the effect
New synthetic routes to cycloheptadienyl and cyclo-
octadienyl tungsten complexes have been developed.
The synthetic route previously applied to a range of
dicarbonyl cycloheptadienyl molybdenum complexes
of the type [Mo(CO)2L2(g5-C7H9)]þ (based on reaction
of ligands L2 with [Mo(CO)2(NCMe)3(g3-C7H9)]þ) was
not viable in the corresponding chemistry of tungsten.
However, representative examples of the hitherto un-
known general formulation [W(CO)2L2(g5-C7H9)]þ
(L2 ¼ 2 PPh3, dppm) were obtained via specific methods.
The solid-state structure of [W(CO)2(PPh3)2(g5-C7H9)]
[BF4] shows no unusual features attributable to the edge
bridge of the cycloheptadienyl ligand. The first examples
of cyclooctadienyl tungsten complexes [WBr(CO)2(NC
Me)2(1–3-g:5,6-C8H11)] and [WBr(CO)2(NCMe)2(1–3-
g:4,5-C8H11)] were synthesised by reaction of [W(CO)3
(NCR)3] with appropriate bromo-cyclooctadienes in a
procedure directly analogous to that employed for mo-
lybdenum. These complexes served as precursors to
the first examples of the pentahapto-bonded ligands
1–3:5,6-g-C8H11 and 1–5-g-C8H11 coordinated to
tungsten.
Three examples of differences between the chemistry
of analogous molybdenum and tungsten systems have
been noted. First, the reactivity of [M(CO)3(g5-C7H9)]þ
(M ¼ Mo or W) towards CO addition and formation of
[M(CO)4(g5-C7H9)]þ is M dependent and proceeds only
for M ¼ Mo. This proved to be a major limitation on the
development of cycloheptadienyl tungsten chemistry
because [W(CO)3(g5-C7H9)]þ is isolable only in rela-
tively low yield. Second, comparison of the stability of
[M(CO)2(NCMe)(dppm)(1–3-g:5,6-C8H11)][BF4] (M ¼
Mo or W) towards loss of NCMe suggests that the g3-
C8H11 acetonitrile adduct is marginally stabilised by
M ¼ W. However, the effect is insufficient to promote
significant differences in reactivity between [M(CO)2
(dppm)(g5-C7H9)]þ (M ¼ Mo or W) both of which are
inert towards adduct formation with NCMe. Finally the
contrasting stability of [M(CO)2(dppe)(1–5-g-C8H11)]þ
(M ¼ Mo or W) towards decomposition to [M(CO)3
(dppe)(1–3-g:4,5-C8H11)]þ may be accounted for in
part, by the enhanced metal carbonyl bond strength in
the tungsten derivative.
of
M
(M ¼ Mo or W) on the stability of [M
(CO)2(NCMe)(dppm)(1–3-g:5,6-C8H11)][BF4] with re-
spect to dissociation of NCMe and accompanying
g3 ! g5 hapticity conversion of the cyclooctadienyl li-
gand. When [Mo(CO)2(NCMe)(dppm)(1–3-g:5,6-C8
H11)][BF4] is dissolved in CH2Cl2, it rapidly eliminates
NCMe with complete conversion to [Mo(CO)2
(dppm)(1–3:5,6-g-C8H11)][BF4] [6]. However, when 10
was dissolved in CH2Cl2, reversion to [W(CO)2
(dppm)(1–3:5,6-g-C8H11)][BF4] (9) proceeded much
more slowly. Thus, for similar concentrations (ca. 0.05 g
in 5 cm3), the molybdenum derivative lost NCMe al-
most instantaneously whereas monitoring by infrared
spectroscopy in CH2Cl2 revealed that the tungsten
complex 10, required several hours to complete con-
version to 9.
The second target of this investigation was to prepare
[W(CO)2(dppe)(1–5-g-C8H11)][BF4]. The molybdenum
analogue of this complex is unstable with respect to
decomposition to [Mo(CO)3(dppe)(1–3-g:4,5-C8H11)]þ
[6]; however, we anticipated that stronger W–CO bonds
might render the tungsten derivative more resistant to
this decomposition pathway. Reaction of [WBr(CO)2
(NCMe)2(1–3-g:4,5-C8H11)] (7) with dppe in CH2Cl2
gave [WBr(CO)2(dppe)(1–3-g:4,5-C8H11)] (11) via li-
gand substitution. Subsequent reaction of 11 with
Ag[BF4] in CH2Cl2 led to the successful isolation of
[W(CO)2(dppe)(1–5-g-C8H11)][BF4]. CH2Cl2 (12) as an
orange-pink solid. The CH2Cl2 solvation of 12 is con-
sistent with our observations for [Mo(CO)2(dppe)(1–
3:5,6-g-C8H11)][BF4]. CH2Cl2 [6]. Complex 12 provides
the first example of the 1–5-g-C8H11 coordinated to
tungsten and has no direct analogue in cyclooctadienyl
molybdenum chemistry. Its successful synthesis high-
lights a further effect of the exchange of molybdenum
for tungsten.
The NMR spectroscopic data for the g3-C8H11 com-
plexes 6–8, 10 and 11 are very similar to the Mo ana-
logues including the observation of isomeric forms of
[WBr(CO)2(dppm)(1–3-g:5,6-C8H11)] (8) and [W(CO)2
(NCMe)(dppm)(1–3-g:5,6-C8H11)][BF4] (10) at low
temperature. The NMR data for the g5-C8H11 com-
plexes 9 and 12 are again typical of 1–3:5,6-g-C8H11 and
1–5-g-C8H11 ligands although well resolved spectra for
12 were obtained only on cooling to )30 °C.
4. Experimental
4.1. General procedures
The preparation, purification and reactions of the
complexes described were carried out under dry nitro-
gen. All solvents were dried by standard methods, dis-
tilled and deoxygenated before use. The compound
[W(CO)3(g6-C7H8)] [23] and bromocyclooctadienes

K.P. Carruthers et al. / Journal of Organometallic Chemistry 689 (2004) 848–859
857
[24,25] were prepared by published procedures. Silica for
column chromatography (70–230 mesh) was purchased
from Lancaster Synthesis and HBF4 (as a 54 wt% so-
lution in diethyl ether) was supplied by Aldrich. 300
sequent recrystallisation from NCMe-diethyl ether fol-
lowed by CH2Cl2-diethyl ether yielded 3 as an orange
solid; yield 0.050 g (9%).
MHz H and 75 MHz 13C{1H} NMR spectra were re-
4.5. Preparation of [W(CO)2(PPh3)(g6-C7H8)]
1
corded on Bruker AC 300 E, Varian Associates XL 300
or Varian Unity Inova 300 spectrometers; 121.5 MHz
31P{1H} NMR spectra were recorded on the Varian
Unity Inova 300 instrument. Infrared spectra were ob-
tained on a Perkin–Elmer FT 1710 spectrometer and
mass spectra were recorded using Kratos Concept 1S
(FAB spectra) or Micromass Platform II (ES spectra)
instruments. Microanalyses were by the staff of the
Microanalytical Service of the Department of Chemis-
try, University of Manchester.
A stirred suspension of [W(CO)2(PPh3)(g-C7H7)]
[BF4] (2.704 g, 3.98 mmol) in THF (120 cm3) was cooled
to 0 °C and treated with Na[BH4] (0.227 g, 5.96 mmol)
over a period of 20 min. The reaction mixture was then
allowed to warm to room temperature and stirred for
1 h to give a deep red solution which was filtered and
evaporated to dryness. The residue was recrystallised
from CH2Cl2-n-hexane to give [W(CO)2(PPh3)(g6-
C7H8)] as a bright red solid; yield 1.445 g (61%).
IRm(CO)(CH2Cl2)(cmꢁ1) 1903, 1817; Microanalysis:
Found (Calc.) C, 54.0 (54.5); H, 3.8 (3.9); 1H NMR
(CDCl3, 300 MHz), numbering as in Scheme 1: 7.50,
4.2. Preparation of [W(CO)3(g5-C7H9)][BF4] (1)
A purple solution of [W(CO)3(g6-C7H8)] (0.148 g,
0.41 mmol) in CH2Cl2 (20 cm3) was treated with
H[BF4] ꢀ Et2O (0.330 g of a 54 wt% solution in diethyl
ether) at 0 °C. The reaction mixture was allowed to
warm to room temperature, stirred for 30 min, then
reduced in volume to initiate precipitation of a pale
orange solid which was completed by addition of 40 cm3
of diethyl ether. The mother liquors were removed and
the product was washed with diethyl ether and then
recrystallised from CH2Cl2-diethyl ether; yield 0.046 g
(25%).
7.40, m, 15H, Ph; 5.70, m, 2H, H3;4; 4.68, m, 2H, H2;5
;
0
3.20, m, 2H, H1;6; 2.94, m, 2H, H7;7
.
4.6. Preparation of [W(CO)2(PPh3)2(g5-C7H9)][BF4]
(4)
A mixture of [W(CO)2(PPh3)(g6-C7H8)] (1.445 g,
2.43 mmol) and PPh3 (0.637 g, 2.43 mmol) in solution in
THF (50 cm3) was cooled in ice. The reaction mixture
was treated with HBF4 ꢀ Et2O (0.648 g of a 54 wt% so-
lution in diethyl ether) resulting in a rapid colour change
from red to yellow brown and after 10 min the ice bath
was removed. Further stirring for 1 h resulted in pre-
cipitation of the product as a bright yellow solid which
was collected by filtration and washed with THF (15
cm3) then diethyl ether; yield 1.731 g (75%).
4.3. Preparation of [WI(CO)3(g5-C7H9)] (2)
A purple solution of [W(CO)3(g6-C7H8)] (0.501 g,
1.39 mmol) in diethyl ether (30 cm3) was cooled to 0 °C,
then treated with H[BF4] ꢀ Et2O (0.260 g of a 54 wt%
solution in diethyl ether). The reaction mixture was
stirred for 1 h at 0 °C. Then the volume was reduced to
ca. 2 cm3. The reaction mixture was redissolved in AR
acetone (50 cm3), cooled to )78 °C and NaI (0.625 g,
4.17 mmol) added. After stirring for 1 h, solvent was
removed and the residue recrystallised from CH2Cl2-
hexane then diethyl ether-hexane to give 2 as a yellow-
orange solid; yield 0.262 g (39%). Complex 2 can also be
purified by chromatography on a silica-n-hexane column
from which it is eluted as a yellow band with CH2Cl2/n-
hexane (1:1).
4.7. Preparation of [W(CO)2(dppm)(g5-C7H9)][BF4]
(5)
A purple solution of [W(CO)3(g6-C7H8)] (0.500 g,
1.39 mmol) in CH2Cl2 (40 cm3), cooled in an ice bath (0
°C), was treated with H[BF4] ꢀ Et2O (0.40 g of a 54 wt%
solution in diethyl ether). The reaction mixture was
stirred for 30 min. Then, dppm (0.64 g 1.67 mmol) was
added followed by warming to room temperature and
stirring for 40 min. After this time the solution was re-
duced in volume and transferred to a silica-CH2Cl2
chromatography column. Elution with CH2Cl2/acetone
(1:1) gave a yellow band followed by an orange band,
which was collected and evaporated to dryness. The
residue, tentatively formulated as [W(CO)3(dppm-
P0 )(g5-C7H9)][BF4], was dissolved in 2-butanone (40
cm3) and the solution refluxed for 30 min, then evapo-
rated to dryness. The residue was dissolved in CH2Cl2
and transferred to a silica-CH2Cl2 chromatography
column and the product eluted as an orange-red band
with CH2Cl2/acetone (1:1). The band was collected,
4.4. Preparation of [W(CO)2(NCMe)3(g3-C7H9)]
[BF4] (3)
An orange solution of [WI(CO)3(g5-C7H9)] (0.506 g,
1.04 mmol) in NCMe (40 cm3) was treated with Ag[BF4]
(0.201 g, 1.03 mmol). The solution turned green with
precipitation of AgI and after 30 min, the reaction
mixture was filtered, reduced in volume and diethyl
ether added to precipitate the crude product. Sub-

858
K.P. Carruthers et al. / Journal of Organometallic Chemistry 689 (2004) 848–859
evaporated to dryness and the residue recrystallised
from CH2Cl2- diethyl ether to give 5 as an orange-red
solid; yield 0.116 g (10% based on [W(CO)3(g6-C7H8)]).
crude product as an orange solid. Subsequent recrys-
tallisation from CH2Cl2 afforded 9 as an orange solid;
yield 0.544 g (54%). Orange-pink [W(CO)2(dppe)(1–5-g-
C8H11)][BF4]. CH2Cl2 (12) was similarly prepared in
40% yield starting from [WBr(CO)2(dppe)(1–3-g:4,5-
C8H11)] (0.186 g, 0.225 mmol) and Ag[BF4] (0.044 g,
0.226 mmol) stirred in CH2Cl2 for 1 h.
4.8. Preparation of [WBr(CO)2(NCMe)2(1–3-g:5,6-
C8H11)] (6)
W(CO)6 (4.15 g, 11.79 mmol) was refluxed in NCMe
(50 cm3) for 4 days after which time a yellow solution of
[W(CO)3(NCMe)3] had formed. This was cooled to
room temperature and a mixture of 3-Br-1,5-cod and 6-
Br-1,4-cod (2.30 g, 12.30 mmol) added, resulting in an
orange solution. The solution was stirred for 1 h and
then the volume was reduced under vacuum, initiating
precipitation of the product. The reaction mixture was
refrigerated for 24 h. Then the mother liquors were re-
moved giving 6 as an orange solid; yield 1.60 g (27%
based on W(CO)6).
4.12. Preparation of [W(CO)2(NCMe)(dppm)(1–3-
g:5,6-C8H11)][BF4] (10)
A
solution of [W(CO)2(dppm)(1–3:5,6-g-C8H11)]
[BF4] (9) (0.540 g, 0.66 mmol) in NCMe (30 cm3) was
stirred for 2 h, then reduced in volume and treated with
diethyl ether to precipitate 10 as a bright yellow solid;
yield 0.454 g (80%).
4.13. X-ray crystal structure of [W(CO)2(PPh3)2(g5-
C7H9)][BF4] ꢀ 0.5CH2Cl2 (4)
4.9. Preparation of [WBr(CO)2(NCMe)2(1–3-g:4,5-
C8H11)] (7)
The majority of details of the structure analyses car-
ried out on 4 are given in Table 4; data were collected on
a Bruker APEX diffractometer. Data collection, cell
refinement and data reduction were carried out with
BRUKER SMART and BRUKER SAINT software; SHELXS
97 [26] was employed for the computing structure so-
lution and SHELXL 97 [27] for the computing structure
refinement. Single crystals of 4 ꢀ 0.5CH2Cl2 were ob-
tained as yellow needles by vapour diffusion of diethyl
ether into a CH2Cl2 solution of the complex. A crystal
of dimensions 0.20 ꢄ 0.08 ꢄ 0.02 mm was selected for
analysis. An absorption correction was applied with the
A stirred solution of [W(CO)3(NCPrn)3] (0.919 g, 1.93
mmol) in NCMe (30 cm3) was treated with a mixture of
5-Br-1,3-cod and 3-Br-1,4-cod (0.470 g, 2.51 mmol) re-
sulting in an orange solution. The solution was stirred
for 1 h and then the volume was reduced under vacuum,
initiating precipitation of the product. The mother li-
quors were separated giving 7 as an orange-yellow solid;
yield 0.362 g (37%).
4.10. Preparation of [WBr(CO)2(dppm)(1–3-g:5,6-
C8H11)] (8)
Reaction of [WBr(CO)2(NCMe)2(1–3-g:5,6-C8H11)]
(0.992 g, 1.95 mmol) with dppm (0.748 g, 1.95 mmol) in
CH2Cl2 (40 cm3) gave a red solution which was stirred
at room temperature for 20 min. The reaction mixture
was then filtered and the product precipitated as an
orange solid by addition of hexane and reduction of the
volume of the solution in vacuo; yield 1.42 g (90%).
Orange [WBr(CO)2(dppe)(1–3-g:4,5-C8H11)] (11) was
similarly prepared in 89% yield starting from
[WBr(CO)2(NCMe)2(1–3-g:4,5-C8H11)] (0.248 g, 0.487
mmol) and dppe (0.198 g, 0.497 mmol) stirred in CH2Cl2
for 1 h and 30 min.
Table 4
Crystal data and refinement parameters for [W(CO)2(PPh3)2(g5-
C7H9)][BF4] ꢀ 0.5CH2Cl2
Formula
C45H39P2O2BF4 ꢀ 0.5CH2Cl2
986.83
Mass
Crystal system
Monoclinic
293(2)
Temperature (K)
ꢀ
k (A)
Crystal system
0.71073 (Mo Ka)
monoclinic
C2=c
35.267(4)
11.2128(13)
23.720(3)
Space group
ꢀ
a (A)
ꢀ
b (A)
ꢀ
c (A)
b (°)
120.395(2)
8090.7(17); 8
30.58
V (A3); Z
Absorption coefficient (cmꢁ1
)
4.11. Preparation of [W(CO)2(dppm)(1–3:5,6-g-
C8H11)][BF4] (9)
h range (°)
1.75–25.03
ꢃ41, ꢃ13, ꢃ28
7132
Limiting indices (h, k, l)
Total reflections
Independent reflections,
I > 2rðIÞ
A yellow-orange solution of [WBr(CO)2(dppm)(1–3-
g:5,6-C8H11)] (1.00 g, 1.23 mmol) was dissolved in
CH2Cl2 (40 cm3) and treated with Ag[BF4] (0.30 g, 1.54
mmol). After stirring for 1 h and 30 min, the reaction
mixture was filtered to give a red solution which was
reduced in volume and diethyl ether added to give the
5455
R1
0.0792
0.1402
wR2
Maximum and minimum
difference Fourier peaks (e A3)
2.601/)3.457

K.P. Carruthers et al. / Journal of Organometallic Chemistry 689 (2004) 848–859
859
[4] R.L. Beddoes, J.R. Hinchliffe, A.-L.A.B. de Souza, M.W.
Whiteley, J. Chem. Soc., Dalton Trans. (1994) 2303.
[5] D.M. Spencer, R.L. Beddoes, R.K. Dissanayake, M. Helliwell,
M.W. Whiteley, J. Chem. Soc., Dalton Trans. (2002) 1009.
[6] D.M. Spencer, R.L. Beddoes, M. Helliwell, M.W. Whiteley,
J. Chem. Soc., Dalton Trans. (2003) 638.
aid of the SADBS programme [28]. The structure was
solved by the Patterson method with refinement by full-
matrix least squares based on F 2. The asymmetric unit
contains the W complex, a BF4 ion and one half of a
CH2Cl2 molecule. The F atoms of the BF4 ion were
disordered such that there were two sites for each F and
the occupancies were constrained to sum to 1.0. All non-
hydrogen atoms were refined anisotropically with the
exception of F(1A); hydrogen atoms were included in
calculated positions.
[7] J.R. Hinchliffe, M.W. Whiteley, J. Organomet. Chem. 402 (1991)
C50.
[8] A. Salzer, H. Werner, Z. Anorg. Allg. Chem. 418 (1975) 88.
ꢁ
[9] N. ElMurr, M. Riveccie, A. Salzer, Inorg. Chim. Acta 29 (1978)
L213.
[10] W. Chen, J.B. Sheridan, M.L. Cote, R.A. Lalancette, Organo-
metallics 15 (1996) 2700.
ꢁ
[11] C.G. Krieter, G. Wendt, J. Kaub, Chem. Ber. 122 (1989) 215.
[12] W. Beck, K. Schloter, Z. Naturforsch. 33b (1978) 1214.
[13] A. Salzer, H. Werner, J. Organomet. Chem. 87 (1975) 101.
[14] V.R. Panter, M.L. Ziegler, Z. Anorg. Allg. Chem. 453 (1979)
14.
5. Supplementary material
Crystallographic data for the structural analysis has
been deposited with the Cambridge Crystallographic
Data Centre, CCDC No. 219846 for compound 4. These
data can be obtained free of charge via www.ccdc.cam.
ac.uk/conts/retrieving.html (or from the CCDC, 12
Union Road, Cambridge, CB2 1EZ, UK; fax: +44 1223
336033; e-mail: deposit@ccdc.cam.ac.uk.
[15] R. Breeze, M.S. Plant, A. Ricalton, D.J. Sutton, M.W. Whiteley,
J. Organomet. Chem. 356 (1988) 343.
[16] T.E. Waldman, A.L. Rheingold, R.D. Ernst, J. Organomet.
Chem. 401 (1991) 331.
[17] D. Baudry, M. Ephritikhine, H. Felkin, Y. Jeannin, F. Robert,
J. Organomet. Chem. 220 (1981) C7.
[18] M.C.L. Trimarchi, M.A. Green, J.C. Huffman, K.G. Caulton,
Organometallics 4 (1985) 514.
[19] T.E. Waldman, B. Waltermire, A.L. Rheingold, R.D. Ernst,
Organometallics 12 (1993) 4161.
Acknowledgements
[20] F.A. Cotton, J.H. Meadows, Inorg. Chem. 23 (1984) 4688.
[21] M. Boyer, J.C. Daran, Y. Jeannin, J. Organomet. Chem. 190
(1980) 177.
We are grateful to the EPSRC for the award of Re-
search Studentships (to J.R.H. and D.M.S.).
[22] R.L. Beddoes, Z.I. Hussain, A. Roberts, C.R. Barraclough, M.W.
Whiteley, J. Chem. Soc., Dalton Trans. (1996) 3629.
[23] G. Kubas, Inorg. Chem. 22 (1983) 692.
[24] S. Moon, C.R. Ganz, J. Org. Chem. 34 (1969) 465.
[25] S. Moon, C.R. Ganz, J. Org. Chem. 35 (1970) 1241.
[26] G.M. Sheldrick, SHELXS 97, Program for Crystal Structure
References
€
€
[1] R.D. Ernst, Chem. Rev. 88 (1988) 1255.
Solution, Universitat Gottingen, Germany, 1997.
[27] G.M. Sheldrick, SHELXL 97, Program for Crystal Structure
[2] V. Kulsomphob, R. Tomaszewski, A.L. Rheingold, A.M. Arif,
R.D. Ernst, J. Organomet. Chem. 655 (2002) 158.
[3] R.L. Beddoes, J.R. Hinchliffe, M.W. Whiteley, J. Chem. Soc.,
Dalton Trans. (1993) 501.
€
€
Refinement, Universitat Gottingen, Germany, 1997.
[28] G.M. Sheldrick, SADABS, An Empirical Absorption Corrections
€
€
Program, Universitat Gottingen, Germany, 1997.