The synthesis and characterisation of a series of linear triphos {PhP(CH2CH2PPh2)2} bridged iron/tungsten or molybdenum bimetallic complexes

Article abstract of DOI:10.1016/S0020-1693(99)00490-9

The reaction of [Fe₂(CO)₉] with 2 equiv. of L(a,b.c) {L(a.b,c) = [MX₂(CO){PhP(CH₂CH₂PPh₂)₂-P,P'}(η²-RC₂R')] {M = W, X = I; L(a), R = R' = Me; L(b) = R = R' = Ph; L(c) = R = Me, R' = Ph} in CH₂Cl₂ at room temperature gives the bimetallic linear triphosbridged complexes [Fe(CO)₄L(a.b,c)] (1-3) in good yield. Equimolar quantities of [FeI(CO)₂Cp or Cp'] and L(a,b,c,d,e,f (L(d), M = Mo, X = I, R = R' = Me; L(e), M = Mo, X = I, R = R' = Ph; L(f), M = W, X = Br, R = R' = Ph) react in CH₂Cl₂ at room temperature to afford the cationic phosphine-bridged complexes [Fe(CO)₂(L(a.b,c.d.e.f))(Cp or Cp')]I (for L(a.b.c), Cp or Cp'; for L(d,e.f), Cp only) 4-12 in good yield. Treatment of [Fe(CO)₂L(a)Cp]I with 1 equiv. of Na[BPh₄] in CH₂Cl₂ at room temperature yields the iodide exchanged product, [Fe(CO)₂L(a)Cp][BPh₄] (13). Equimolar quantities of [Fe(CO)₄L(a)] and L {L = CNBu(t) or P(OMe)₃ gives the iron-carbonyl substituted products [Fe(CO)₃LL(a)] (14-15) in good yield. Complexes 1-15 have been characterised by elemental analysis (C, H and N), IR and ¹H and ³¹P NMR spectroscopy. (C) 2000 Elsevier Science S.A.

Full text of DOI:10.1016/S0020-1693(99)00490-9

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Inorganica Chimica Acta 303 (2000) 17–23
The synthesis and characterisation of a series of linear triphos
{PhP(CH2CH2PPh2)2} bridged iron/tungsten or molybdenum
bimetallic complexes
Paul K. Baker *, Margaret M. Meehan
Department of Chemistry, Uni6ersity of Wales, Bangor, Gwynedd LL57 2UW, Wales, UK
Received 14 July 1999; accepted 27 September 1999
Abstract
The reaction of [Fe2(CO)9] with 2 equiv. of La,b,c {La,b,c=[MX2(CO){PhP(CH2CH2PPh2)2-P,P%}(h2-RC2R%)] {M=W, X=I;
La, R=R%=Me; Lb=R=R%=Ph; Lc=R=Me, R%=Ph} in CH2Cl2 at room temperature gives the bimetallic linear triphos-
bridged complexes [Fe(CO)4La,b,c] (1–3) in good yield. Equimolar quantities of [FeI(CO)2Cp or Cp%] and La,b,c,d,e,f (Ld, M=Mo,
X=I, R=R%=Me; Le, M=Mo, X=I, R=R%=Ph; Lf, M=W, X=Br, R=R%=Ph) react in CH2Cl2 at room temperature to
afford the cationic phosphine-bridged complexes [Fe(CO)2(La,b,c,d,e,f)(Cp or Cp%)]I (for La,b,c, Cp or Cp%; for Ld,e,f, Cp only) 4–12
in good yield. Treatment of [Fe(CO)2LaCp]I with 1 equiv. of Na[BPh4] in CH2Cl2 at room temperature yields the iodide exchanged
product, [Fe(CO)2LaCp][BPh4] (13). Equimolar quantities of [Fe(CO)4La] and L {L=CNBut or P(OMe)3} gives the iron-carbonyl
substituted products [Fe(CO)3LLa] (14–15) in good yield. Complexes 1–15 have been characterised by elemental analysis (C, H
1
and N), IR and H and 31P NMR spectroscopy. © 2000 Elsevier Science S.A. All rights reserved.
Keywords: Iron complexes; Tungsten complexes; Alkyne complexes; Bimetallic complexes; Linear triphos-bridged complexes; Carbonyl complexes
1. Introduction
R%=Ph) of the organotungsten–phosphine ligands,
[WI2(CO){PhP(CH2CH2PPh2)2-P,P%}(h2-RC2R%)] (R=
R%=Me, Ph; R=Me, R%=Ph). In this paper we de-
scribe the reactions of these organotungsten–phosphine
ligands, La,b,c{[WI2(CO){PhP(CH2CH2PPh2)2-P,P%}(h2-
RC2R%)]; La, R=R%=Me; Lb, R=R%=Ph; Lc, R=Me,
R%=Ph} and the related complexes, Ld,e,f{[MX2-
(CO){PhP(CH2CH2PPh2)2-P,P%}(h2-RC2R)]; Ld, M=
Mo, X=I, R=Me; Le, M=Mo, X=I, R=Ph; Lf,
M=W, X=Br, R=Ph}, which have recently been de-
scribed [30] with [Fe2(CO)9], [FeI(CO)2Cp or Cp%] to give
a range of new bimetallic linear triphos-bridged com-
plexes.
Since the early reports of the synthesis of
trimethylphosphine by Thenard and Hebd [1] in 1847
and triphenylphosphine by Michaelis and Soden [2] in
1885, phosphine donor ligands have played a very sig-
nificant role in transition metal chemistry over many
years [3–5], including homogeneous catalysis [6–10]. In
recent years, the development of bi- and multimetallic
complexes containing phosphine bridges has flourished
[11–27]. Very recent examples of Fe/Cr, Mo and W
dppm-bridged {dppm=Ph2P(CH2)PPh2} complexes
[CpFe(CO)(m-I)(m-dppm)M(CO)4] (M=Cr, Mo, W)
have been reported in 1998 [28]. Up until this paper, no
examples of Fe, W or Mo bimetallic complexes contain-
ing bridging linear triphos {PhP(CH2CH2PPh2)2} have
been reported.
2. Experimental
In 1996 [29], we described the synthesis and crystallo-
graphic characterisation (for R=R%=Me; R=Me,
All reactions described in this paper were carried out
using standard vacuum/Schlenk line techniques under an
atmosphere of dry nitrogen. The starting materials, [Fe-
I(CO)2Cp or Cp%] (Cp=C5H5; Cp%=C5H4Me) [31]
and [WI2(CO){PhP(CH2CH2PPh2)2-P,P%}(h2-RC2R%)]
* Corresponding author. Tel.: +44-1248-382 379; fax: +44-1248-
370 528.
E-mail address: chs018@bangor.ac.uk (P.K. Baker)
0020-1693/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0020-1693(99)00490-9

18
P.K. Baker, M.M. Meehan / Inorganica Chimica Acta 303 (2000) 17–23
[Fe(CO)4(La or Lb)] (1) and 2. For physical and analyt-
ical data see Table 1.
(R=R%=Me, Ph; R=Me, R%=Ph) [29] and [MX2-
(CO){PhP(CH2CH2PPh2)2-P,P%}(h2-RC2R)] (M=Mo,
X=I, R=Me or Ph; M=W, X=Br, R=Ph) [30]
were prepared by published methods. All other chemi-
cals used were purchased from commercial sources. All
solvents used were dried and distilled before use.
2.2. Preparation of [Fe(CO)2LaCp]I {La=[WI2(CO)-
{PhP(CH2CH2PPh2)2-P,P%}(p2-MeC2Me)]} (4)
To a solution of [FeI(CO)2Cp] (0.14 g, 0.47 mmol)
dissolved in CH2Cl2 (30 cm3) in a Schlenk tube in a
warm water bath (40°C) [WI2(CO){PhP(CH2CH2-
PPh2)2-P,P%}(h2-MeC2Me)] (0.5 g, 0.47 mmol) was
added and the reaction mixture was stirred for 2 h. The
resulting green solution was filtered through Celite and
the solvent was removed in vacuo giving a green crys-
talline powder of [Fe(CO)2LaCp]I {La=WI2(CO)-
{PhP(CH2CH2PPh2)2-P,P%}(h2-MeC2Me)]} (4), which
was recrystallised from CH2Cl2/Et2O. The yield of pure
product was 0.51 g, 81%.
Similar reactions of equimolar quantities of [Fe-
I(CO)2(Cp or Cp%)] (Cp=C5H5; Cp%=C5H4Me), and
La, Lb, Lc, Ld, Le or Lf (see Section 1 for definition of
La to Lf; for La,b,c, Cp or Cp%; Ld,e,f, Cp only) in CH2Cl2
gives the bimetallic complexes [Fe(CO)2(La,Lb,Lc,Ld,Le
or Lf) (Cp or Cp%)]I (5–12). See Table 1 for physical
and analytical data.
Elemental analysis (C, H and N) results were
recorded on a Carlo Erba Elemental Analyser MOD
1108, using helium as a carrier gas. The IR spectra were
recorded as thin CHCl3 films between NaCl plates on a
Perkin–Elmer 1600 series FT IR spectrophotometer.
1H, 31P and the 11B NMR spectra were recorded on a
1
Bruker AC 250 NMR spectrometer; H NMR spectra
are referenced to SiMe4, 31P NMR spectra were refer-
enced to 85% H3PO4 and the 11B NMR spectrum to
50% boronic acid. Molecular weight measurements
were made using Rast’s method [32] using camphor as
the solvent.
2.1. Preparation of [Fe(CO)4Lc] {Lc=[WI2(CO)-
{PhP(CH2CH2PPh2)2-P,P%}(p2-MeC2Ph)]} (3)
To a solution of [Fe2(CO)9] (0.05 g, 0.15 mmol)
dissolved in CH2Cl2 (30 cm3) in a Schlenk tube at room
temperature (r.t.), [WI2(CO){PhP(CH2CH2PPh2)2-
P,P%}(h2-MeC2Ph)] (0.32 g, 0.29 mmol) was added and
the reaction mixture was stirred for 24 h. The resulting
green solution was filtered through Celite and the sol-
vent was removed in vacuo giving a green crystalline
powder of [Fe(CO)4Lc] (3), which was recrystallised
from CH2Cl2/Et2O. The yield of pure product was 0.27
g, 77%.
2.3. Preparation of [Fe(CO)2LaCp][BPh4] (13)
To a solution of [Fe(CO)3LaCp]I (4) (0.4 g, 0.25
mmol) in CH2Cl2 (30 cm3), Na[BPh4] (0.02 g, 0.29
mmol) was added and the solution was stirred for 17 h.
The resultant green solution was filtered through Celite
and the solvent was removed in vacuo to give the green
crystalline powder, [Fe(CO)2LaCp][BPh4] (13), which
was recrystallised from CH2Cl2/Et2O. The yield of pure
product was 0.28 g, 61%.
Similar reactions of 2 equiv. of La or Lb with
[Fe2(CO)9] in CH2Cl2 gave the bimetallic complexes
Table 1
Physical and analytical data a for the Fe/W or Mo bimetallic {PhP(CH2CH2PPh2)2}-bridged complexes 1–15
Complex no.
Complex
Colour
Yield
Analysis (%) a
C
H
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
[Fe(CO)4La]·CH2Cl2
[Fe(CO)4Lb]
[Fe(CO)4Lc]
[Fe(CO)2LaCp]I
[Fe(CO)2LbCp]I
[Fe(CO)2LcCp]I
[Fe(CO)2LdCp]I
[Fe(CO)2LeCp]I·0.5CH2Cl2
[Fe(CO)2LfCp]I·CH2Cl2
[Fe(CO)2LaCp%]I
[Fe(CO)2LbCp%]I
[Fe(CO)2LcCp%]I
[Fe(CO)2LaCp][BPh4]
trans-[Fe(CO)3(CNBut)La]
trans-[Fe(CO)3{P(OMe)3}La]
green
green
green
green
green
green
brown
brown
green
brown
green
green
green
green
green
84
81
77
81
85
82
85
87
84
86
83
81
61
74
85
40.4 (40.4)
47.3 (47.3)
44.3 (44.8)
40.8 (40.7)
45.1 (45.4)
43.3 (43.1)
44.3 (43.5)
47.3 (47.2)
46.3 (46.5)
43.3 (42.9)
47.0 (47.2)
45.1 (45.1)
54.5 (54.2)
42.9 (42.2)
42.3 (41.0)
3.0 (3.0)
3.6 (3.2)
3.5 (3.2)
3.7 (3.3)
3.4 (3.3)
3.7 (3.3)
3.7 (3.5)
3.6 (3.4)
3.5 (3.4)
3.7 (3.8)
4.1 (3.8)
3.4 (3.9)
4.0 (4.2)
3.8 (3.3)
4.0 (3.7)
a Calculated values in parentheses.

P.K. Baker, M.M. Meehan / Inorganica Chimica Acta 303 (2000) 17–23
19
2.4. Preparation of [Fe(CO)3(CNBut)La] (14)
Table 2
Infrared data a for the Fe/W or Mo bimetallic {PhP(CH2-
CH2PPh2)2}-bridged complexes 1–15
To a solution of [Fe(CO)4La] (1) (0.4 g, 0.33 mmol) in
CH2Cl2 (30 cm3), CNBut (0.03 g, 0.04 ml, 0.33 mmol)
was added and the solution was stirred for 30 min. The
resultant green solution was filtered through Celite and
the solvent was removed in vacuo to give the green
crystalline powder [Fe(CO)3(CNBut)La] (14), which was
recrystallised from CH2Cl2/Et2O. The yield of pure
product was 0.31 g, 74%.
A similar reaction of [Fe(CO)4La] (1) with an
equimolar amount of P(OMe)3 in CH2Cl2 gives the
product [Fe(CO)3{P(OMe)3}La] (15). See Table 1 for
physical and analytical data.
Complex
w(CꢀO) (cm−1
)
w(CꢀC) (cm−1
)
1
2
3
4
5
6
7
8
9
10
11
12
13
14 b
15
2049(m), 1978(br), 1958(sh)
2049(m), 1969(br), 1929(sh)
2039(m), 1992(br), 1963(sh)
2040(s), 1981(s), 1962(s)
2039(s), 1994(s), 1957(s)
2039(s), 1994(s), 1956(s)
2041(s), 1995(s), 1954(sh)
2039(s), 1993(s), 1960(sh)
2041(s), 1986(s), 1965(s)
2035(s), 1978(sh), 1950(s)
2036(s), 1978(br), 1963(s)
2035(s), 1988(br), 1955(s)
2040(s), 1981(s), 1961(s)
1956(s), 1886(m)
1589(w)
1658(w)
1589(w)
1588(w)
1587(w)
1587(w)
1601(w)
1573(w)
1601(w)
1588(w)
1686(w)
1601(w)
1601(w)
1590(w)
1589(w)
3. Results and discussion
1961(br), 1883(m)
a Spectra obtained in CHCl3 as thin films between NaCl plates; s,
strong; m, medium; brs, broad strong; sh, shoulder.
The molybdenum and tungsten–phosphine starting
materials used in this research, namely [MX2(CO)-
{PhP(CH2CH2PPh2)2-P,P%}(h2-RC2R%)] (M=W, X=I,
R=R%=Me, Ph; R=Me, R%=Ph [29]; M=Mo, X=
I, R=R%=Me or Ph; M=W, X=Br, R=R%=Ph
[30]) have been prepared by reacting the bis(alkyne)
b w(CꢀN)=2132 cm−1
.
Table 3
1H NMR data a for the Fe/W or Mo bimetallic {PhP(CH2-
CH2PPh2)2}-bridged complexes 1–15
complexes, [MX2(CO)(NCMe)(h2-RC2R%)2] with
1
equiv. of PhP(CH2CH2PPh2)2 in CH2Cl2 at r.t. La,b,c
{La,b,c=[WI2(CO){PhP(CH2CH2PPh2)2 - P,P%}(h2RC2-
R%)] (La, R=R%=Me; Lb, R=R%=Ph; Lc, R=Me,
R%=Ph) (2 equiv.) with [Fe2(CO)9] (1 equiv.) in CH2Cl2
at r.t. to afford the bimetallic Fe(0)/W(II) linear
Complex
1H NMR data [l (ppm)]
1
7.8–7.4 (m, 25H, Ph); 5.3 (s, 2H, CH2Cl2); 3.1 (s,
6H, C2Me); 2.6–2.4 (m, 8H, CH2)
7.8–7.4 (m, 35H, Ph); 2.6–2.4 (m, 8H, CH2)
7.9–7.6 (m, 30H, Ph); 3.0 (s, 3H, C2Me); 2.6–2.4
(m, 8H, CH2)
7.8–7.4 (m, 25H, Ph); 4.3 (m, 5H, Cp); 3.1 (s, 6H,
C2Me); 2.6–2.4 (m, 8H, CH2)
7.8–7.4 (m, 35H, Ph); 4.3 (m, 5H, Cp); 2.6–2.4 (m,
8H, CH2)
2
3
triphos-bridged complexes [Fe(CO)4La,b,c] (1–3) in
good yield. Complexes 1–3 have been characterised by
4
5
elemental analysis (C, H and N) (Table 1), IR (Table 2)
1
and H and 31P NMR spectroscopy (Tables 3 and 4).
Complex 1 was confirmed as a CH2Cl2 solvate by
repeated elemental analyses and 1H NMR spec-
troscopy. Molecular weight studies using Rast’s method
[32] (Table 5) for complexes 1–3 confirm the bimetallic
nature of these complexes. FAB mass spectrometry was
attempted with these and other complexes described in
this paper without success, as no parent ion was ob-
served. Complexes 1–3 are soluble in dichloromethane
and acetone, less soluble in chloroform, sparingly solu-
ble in methanol and diethyl ether and insoluble in
hydrocarbon sol-vents. The IR spectra (Table 2) of 1–3
all show the expected bands for the bimetallic com-
plexes. For example, the IR spectrum for 1 shows
bands at 2049, 1978 and 1958 cm−1. The bands at 2049
and 1978 cm−1 are in similar positions to the com-
plexes [Fe(CO)4L] {L=P(o-tolyl)3, w(CO), (hexane)=
2043, 1975 and 1947 cm−1} [33]. The broad band at
1958 cm−1 must be due to a combination of the car-
bonyl group bonded to the tungsten centre in the unit
[WI2(CO){PhP(CH2CH2PPh2)2 - P,P%}(h2 - MeC2Me)],
which has w(CO) (CHCl3)=1957 cm−1, and one band
due to [Fe(CO)4La]. It would not be expected that
6
7.8–7.4 (m, 30H, Ph); 4.3 (m, 5H, Cp); 3.0 (s, 3H,
C2Me); 2.6–2.4 (m, 8H, CH2)
7.8–7.6 (m, 25H, Ph); 4.3 (m, 5H, Cp); 3.1 (s, 6H,
C2Me); 2.6–2.4 (m, 8H, CH2)
7.8–7.6 (m, 35H, Ph); 5.3 (s, 1H, CH2Cl2); 4.3 (s,
5H, Cp); 2.7–2.4 (m, 8H, CH2)
7.8–7.4 (m, 35H, Ph); 5.3 (s, 2H, CH2Cl2); 4.3 (m,
5H, Cp); 3.0 (s, 6H, C2Me); 2.6–2.4 (m, 8H, CH2)
7.7–7.4 (m, 25H, Ph); 4.9, 4.8 (2s, H, Cp%); 3.1, 3.0,
2.95, 2.9 (4s, 6H, C2Me); 2.6–2.4 (m, 8H, CH2);
1.15 (s, 3H, Cp%–Me)
7.8–7.4 (m, 35H, Ph); 4.95, 4.85 (2s, 4H, Cp%); 2.6–
2.4 (m, 8H, CH2); 1.3 (s, 3H, Cp%–Me)
7.9–7.4 (m, 30H, Ph); 4.9, 4.8 (2s, 4H, Cp%); 3.1 (s,
3H, C2Me); 2.7–2.5 (m, 8H, CH2); 1.0 (s, 3H, Cp%–
Me)
7
8
9
10
11
12
13
14
15
7.7–7.3 (m, 45H, Ph); 4.3 (m, 5H, Cp); 3.0 (s, 6H,
C2Me); 2.8–2.6 (m, 8H, CH2)
7.9–7.6 (m, 25H, Ph); 3.1 (s, 6H, C2Me); 2.8–2.6
(m, 8H, CH2); 1.1 (s, 9H, But)
7.8–7.4 (m, 25H, Ph); 3.5 (d, 9H, OMe); 3.1 (s,
6H, C2Me); 2.6–2.4 (m, 8H, CH2)
a Spectra recorded in CDCl3 (+25°C) and referenced to SiMe4; d,
doublet; m, multiplet; s, singlet.

20
P.K. Baker, M.M. Meehan / Inorganica Chimica Acta 303 (2000) 17–23
Table 4
31P{1H} NMR data a for the Fe/W or Mo bimetallic {PhP(CH2CH2PPh2)2}-bridged complexes 1–15
Complex
31P {1H} NMR data [l (ppm)]
1
31.1 (brm, 2P, FeꢁPPh2); 22.5 (m, 1P, WꢁPPh); 20.1 (m, 1P, WꢁPPh); 3.7 (m, 1P, WꢁPPh2); −2.3 (m, 1P, JW–P=220 Hz,
WꢁPPh2
2
3
30.1 (brm, P, FeꢁPPh2); 25.0 (m, 1P, WꢁPPh); 20.6 (m, 1P, WꢁPPh); −4.3 (m, 2P, WꢁPPh2)
30.6 (brm, 1P, FeꢁPPh2); 23.4 (m, 1P, FeꢁPPh); 21.7 (m, 1P, WꢁPPh); 19.8 (m, 1P, WꢁPPh); 6.5 (m, 1P, JW–P=198 Hz,
WꢁPPh2); −0.4 (brm, 1P, WꢁPPh2)
4
5
30.3 (brm, 2P, FeꢁPPh2); 22.4 (m, 1P, WꢁPPh); 19.2 (m, 1P, WꢁPPh); 3.7 (m, 1P, JW–P=215 Hz, WꢁPPh2); −2.2 (m, 1P,
WꢁPPh2)
30.1 (brm, 2P, FeꢁPPh2); 23.3 (m, 1P, WꢁPPh); 19.6 (m, 1P, WꢁPPh); 7.0 (m, 1P, WꢁPPh2); −1.1 (m, 1P, JW–P=207 Hz,
WꢁPPh2)
6
7
52.9 (m, 2P, FeꢁPPh2); 4.9 (m, 1P, WꢁPPh); 47.8 (m, 1P, WꢁPPh); 44.7 (d, 1P, FeꢁPPh2); 32.8 (m, 2P, WꢁPPh2)
34.3 (brm, 1P, FeꢁPPh2); 31.2 (m, 1P, FeꢁPPh2); 19.8 (m, 1P, WꢁPPh); 14.5 (m, 1P, WꢁPPh); 4.4 (m, 1P, WꢁPPh2); −2.5
(m, 1P, WꢁPPh2)
8
9
10
35.2 (m, 1P, FeꢁPPh2); 29.8 (m, 1P, WꢁPPh); 5.2 (m, 1P, WꢁPPh2)
38.9 (m, 2P, FeꢁPPh2); 22.7 (m, 1P, WꢁPPh); 19.5 (m, 1P, WꢁPPh); 6.7 (m, 1P, WꢁPPh2); −3.2 (m, 1P, WꢁPPh2)
64.6 (d, 1P, JP–P=28 Hz, FeꢁPPh2); 63.7 (d, 1P, JP–P=28 Hz, FeꢁPPh2); 40.1 (s, 1P, JW–P=280 Hz, FeꢁPPh2); 24.0 (d,
1P, JP–P=28 Hz, WꢁPPh); 22.1 (m, 1P, WꢁPPh); 19.7 (m, 1P, WꢁPPh); 4.5 (m, 1P, WꢁPPh2); −2.0 (s, 1P, WꢁPPh2);
−4.4 (s, 1P, WꢁPPh2)
11
12
63.8 (m, 2P, FeꢁPPh2); 25.7 (brs, 1P, WꢁPPh); 20.0 (d, 1P, JP–P=31 Hz, 1P, WꢁPPh); 7.5 (m, 1P, WꢁPPh2, JW–P=197
Hz); −4.3 (m, 2P, WꢁPPh2)
63.6 (m, 2P, FeꢁPPh2); 27.0 (s, 1P, WꢁPPh); 25.8 (s, 1P, WꢁPPh); 19.6 (m, 1P, WꢁPPh); 7.5 (m, 1P, WꢁPPh2, JP–P=30
Hz); −4.2 (m, 1P, WꢁPPh2, JW–P=270 Hz)
13
14
15
30.5 (m, 2P, FeꢁPPh2); 25.2 (m, 1P, WꢁPPh); 20.0 (m, 1P, WꢁPPh); −3.9 (m, 2P, WꢁPPh2, JW–P=280 Hz)
31.0 (m, 2P, FeꢁPPh2); 22.9 (m, 1P, WꢁPPh); 19.9 (m, 1P, WꢁPPh); 4.2 (m, 1P, WꢁPPh2); −2.5 (m, 1P, WꢁPPh2)
75.1 {d, 1P, JP–P=231 Hz, trans-P(OMe)3}; 32.6 (d, 1P, JP–P=231 Hz, FeꢁPPh2−-trans); 31 (m, 1P, FeꢁPPh2-trans); 24.5
(m, 1P, WꢁPPh); 13.3 (s, 1P, WꢁPPh); 4.1 (m, 1P, WꢁPPh2); −2.6 (m, 1P, WꢁPPh2)
a Spectra obtained in CDCl3 (+25°C) and referenced to 85% H3PO4.
the carbonyl group would shift very much when the
uncoordinated phosphine in [WI2(CO){PhP(CH2-
CH2PPh2)2-P,P%}(h2-MeC2Me)] becomes attached to
the iron centre in 1. Since the molecular structures of
[Fe(CO)4L] {L=P(o-tolyl)3 [33] or PPh3 [34]} have
been crystallographically determined and have an al-
most identical trigonal bipyramidal geometry to the
phosphine ligand in the axial position, in view of the
similar IR properties of 1–3 to [Fe(CO)4L] [33,34] it is
likely the structures of 1–3 are as shown in Fig. 1. The
reasons for the two isomers comes from the tungsten
part of the molecule. The 31P NMR spectra of 1–3 did
not show a resonance at approximately −13 ppm,
which is due to the uncoordinated phosphorus atoms in
[WI2(CO){PhP(CH2CH2PPh2)2-P,P%}(h2-RC2R%)]. For
example, the 31P NMR spectrum of 1 showed five
resonances at l=31.1 (brm, 2P, FeꢁPPh2); 22.5 (m,
1P, WꢁPPh); 20.1 (m, 1P, WꢁPPh); 3.7 (m, 1P,
WꢁPPh2); −2.3 (m, 1P, WꢁPPh2) ppm. This agrees
with the spectrum obtained for [WI2(CO){PhP-
(CH2CH2PPh2)2-P,P%}(h2-MeC2Me)], which had reso-
nances at l=23.1 (d, 1P, JP–P=30 Hz, C2H4PPh); 19.5
(d, 1P, JP–P=30 Hz, C2H4PPh); 4.3 (s, 1P, C2H4PPh);
−2.7 (s, 1P, C2H4PPh); −13.7 (m, 2P, C2H4PPh2)
ppm. The X-ray crystal structure of this complex [29]
showed that there were two diastereoisomers in a unit
cell, one with the ꢁCH2CH2PPh2 (uncoordinated) point-
ing up, and the other with ꢁCH2CH2PPh2 (uncoordi-
nated) pointing down. Several unsuccessful attempts to
grow suitable single crystals for X-ray analysis of 1–3
were made. However, it is very likely that the structure
of the two isomers of 1 are as shown in Fig. 1.
Treatment of [FeI(CO)2Cp or Cp%] (Cp=C5H5;
Cp%=C5H4Me) with an equimolar amount of La,b,c,d,e,f
{[MX2(CO){PhP(CH2CH2PPh2)2-P,P%}(h2-RC2R)]; Ld,
M=Mo, X=I, R=Me; Le, M=Mo, X=I, R=Ph;
Table 5
Molecular weight studies a using Rast’s method [32] for the Fe/W or
Mo bimetallic {PhP(CH2CH2PPh2)2}-bridged complexes 1–15
Complex
Molecular weight [calc. (found)]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
1349 (1306)
1358 (1346)
1291 (1285)
1365 (1358)
1496 (1482)
1433 (1421)
1293 (1272)
1401 (1396)
1394 (1386)
1435 (1428)
1567 (1551)
1499 (1491)
1611 (1605)
1198 (1194)
1320 (1318)
a Camphor was used as the solvent in these measurements.

P.K. Baker, M.M. Meehan / Inorganica Chimica Acta 303 (2000) 17–23
21
2045 and 1995 cm−1 [35]. Again, the band at 1962
cm−1 is very similar to that found in [WI2(CO)-
{PhP(CH2CH2PPh2)2-P,P%}(h2-MeC2Me)]
{w(CO)=
1957 cm−1}. Both the H (multiple Cp resonances) and
31P NMR spectra again showed the presence of at least
two isomers of most of complexes 4–13 due to the two
diastereoisomers of the organotungsten phosphine lig-
and precursor, [WI2(CO){PhP(CH2CH2PPh2)2-P,P%}-
(h2-MeC2Me)]. It is interesting to note that the 13P{1H}
NMR spectrum for [Fe(CO)2LeCp]I·0.5CH2Cl2 (8) has
just three resonances (see Table 4), and a single reso-
1
1
nance for the cyclopentadienyl group in its H NMR
spectrum (see Table 3), hence, only one isomer is
present in solution for this complex. The JW–P coupling
was clearly observed in several complexes, hence, as-
signment of the spectra was done by comparison with
the organometallic ligands [MX2(CO){PhP(CH2CH2-
PPh2)2-P,P%}(h2-RC2R)] [29,30]. Many attempts were
made to grow single crystals of 4–13 for X-ray analysis
without success. However, the proposed structure of
two possible isomers of 4–13 is shown in Fig. 2. The
11B NMR spectrum of 13 has a resonance at l= −7
ppm due to the BPh4 counterion.
The reaction of equimolar quantities of [Fe(CO)4La]
{La=[WI2(CO){PhP(CH2CH2PPh2)2 - P,P%}(h2-MeC2-
Me)]} and L {L=CNBut, or P(OMe)3} in CH2Cl2 at
r.t. affords the iron tricarbonyl complexes trans-
[Fe(CO)3LLa] (14, 15) in good yield. Complexes 14 and
15 have been fully characterised in the normal manner
(see Tables 1–5). Complexes 14 and 15 were more
soluble than complexes 1–13 in polar solvents, such as
CHCl3 and CH2Cl2. As observed for other previously
described complexes of the types, trans-[Fe(CO)2L2]
[36,37] and [Fe(CO)3LL%] (L,L%=phosphines and re-
Fig. 1. Proposed structure of the two diastereoisomers of [Fe(CO)4La]
(1).
Lf, M=W, X=Br, R=Ph} in warm (40°C) CH2Cl2
for 2 h gives excellent yields of the cationic bimetallic
complexes [Fe(CO)2La,b,c,d,e,f(Cp or Cp%)]I (4–12) (for
La,b,c, Cp or Cp%; for Ld,e,f, Cp only) presumably via
displacement of the iodide attached to the iron by the
uncoordinated phosphorus atom on the linear triphos
ligand. The cationic nature of these complexes was
established by an iodide exchange reaction. Equimolar
quantities of [Fe(CO)2LaCp]I (1) and Na[BPh4] react in
CH2Cl2 at r.t. to give the tetraphenylborate complex
[Fe(CO)2LaCp][BPh4] (13) in 61% yield. Complexes 4–
13 have been characterised in the normal manner (see
Tables 1–5). Molecular weight studies [32] (Table 5)
again suggest the bimetallic nature of these complexes.
Complexes 8 and 9 were confirmed as 0.5CH2Cl2 and
CH2Cl2 solvates, respectively, by repeated elemental
1
analyses and H NMR spectroscopy. Complexes 4–9
are more soluble in methanol, MeOH, CH2Cl2, CHCl3
and acetone than complexes 1–3, and are similarly
insoluble in hydrocarbon solvents. Complex 8 was more
soluble in the above solvents than complex 5. Com-
plexes 10–12 were more soluble than complexes 1–9.
Complex 13 was sparingly soluble in methanol and less
soluble in CHCl3 than complexes 4–12, and was insolu-
ble in CH2Cl2 and acetone. Complexes 1–13 were
stable when stored in the solid state under nitrogen for
2 months, but considerably less stable in solution. The
IR spectrum of 4 shows carbonyl resonances at 2040
and 1981 cm−1 due to cis-carbonyl groups attached to
the iron centre, and the band at w(CO)=1962 cm−1
due to the single carbonyl group on the tungsten centre.
The two carbonyl bands due to the iron centre are
similar to those found for the related simple phosphine
complexes [Fe(CO)2(PR3)Cp]I. For example, [Fe(CO)2-
(PPh3)Cp]I has carbonyl bands at w(CO) (CHCl3)=
Fig. 2. Proposed structure of two of the diastereoisomers of
[Fe(CO)2La,b,c,d,e,f(Cp or Cp%)]X (4–13).

22
P.K. Baker, M.M. Meehan / Inorganica Chimica Acta 303 (2000) 17–23
Acknowledgements
lated ligands) have trans-geometry with the bulkier
phosphine ligands in the axial positions 180° apart. It is
very likely that the complexes trans-[Fe(CO)3L,La] have
the trans-geometry. This is confirmed by the IR spectra
of 14 and 15, which have two carbonyl stretching
bands. The iron centre in trans-[Fe(CO)3L,La] has an
approximate D3h symmetry if the La is free to rotate
about the phosphorus atoms attached to the metal. For
example, the band at w(CO)=1886 cm−1 for 14 is due
to the Fe(CO)3 unit, and the band at w(CO)=1956
cm−1 due to the WI2(CO) unit. It should be noted that
the IR band for the bis(triphenylphosphine) complex
trans-[Fe(CO)3(PPh3)2] has a carbonyl band at w(CO)
(CH2Cl2)=1885 cm−1 [37], which conforms with the
expected value for complexes 14 and 15. The trans-ge-
M.M.M. thanks the EPSRC for
studentship.
a
research
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