Main group derivatives of a cyclometallated iron carbonyl anion. Crystal structures of Fe(CO)2{P(OPh)3}{(PhO)2POC6H 4}(SnPh3) and two isomers of Fe(CO)2{P(OPh)3}{(PhO)2POC6H 4}(I)

Article abstract of DOI:10.1016/S0020-1693(01)00693-4

The iron hydrido complex HFe(CO)₂{P(OPh)₃}{(PhO)₂POC₆H ₄} (1), was rapidly deprotonated by DBU or [BzMe₃N][OH] in THF to afford the new carbonyl iron anion [Fe(CO)₂{P(OPh)₃}{(PhO)₂POC₆H ₄}]^- ([2]^-), containing an ortho-metallated triphenyl phosphite ligand. Complex [2]^- reacted with triorganostannyl and plumbyl salts and with halogens to give the octahedral Fe^II compounds Fe(CO)₂{P(OPh)₃}{(PhO)₂POC₆H ₄}(X) (X = SnPh₃, 3; SnMe₃, 4; PbPh₃, 5; PbMe₃, 6; Cl, 7; Br, 8; I, 9). The Group 14 complexes 3-6 were obtained in one isomeric form in which the P^III-donor atoms are mutually cis, the carbonyl ligands are cis and the P(OPh)₃ and MR₃ (M = Sn, Pb; R = Ph, Me) groups are trans as determined by solution-state IR, ³¹P and ¹³C NMR spectroscopic data. This geometry was confirmed for 3 by a single crystal X-ray diffraction study. The halide complexes, however, were obtained as a mixture of isomers. The major isomer (7, X = Cl; 8a, X = Br; 9a, X = I) has cis P atoms, trans CO groups and the halide located trans to the phosphorus atom of the ortho-metallated phosphite ligand. The structure of 9a was confirmed by an X-ray diffraction study. Two other isomers, designated 8b (X = Br) and 9b (X = I), with cis P atoms and cis CO groups were isolated from the reactions of [2]^- with Br₂ and I₂, respectively. The structure of the latter was established by X-ray crystallography and is related to 9a by exchange of the P(OPh)₃ ligand and a carbonyl group such that the metal-bound C atom of the five-membered metallacycle is trans to CO. The stereo-geometry of 8b could not be unambiguously assigned from the spectroscopic data; however, two of the seven possible geometric isomers were suggested as plausible structures.

Full text of DOI:10.1016/S0020-1693(01)00693-4

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Inorganica Chimica Acta 327 (2002) 98–107
Main group derivatives of a cyclometallated iron carbonyl anion.
Crystal structures of Fe(CO)2{P(OPh)3}{(PhO)2POC6H4}(SnPh3)
and two isomers of Fe(CO)2{P(OPh)3}{(PhO)2POC6H4}(I)
D. Courtney a, N.L. Cromhout a, D. Cunningham b, J.F. Gallagher c, A.R. Manning a,*,
P. McArdle b, S.I. Pratt a
a Department of Chemistry, Uni6ersity College Dublin, Belfield, Dublin 4, Ireland
b Department of Chemistry, Uni6ersity College Galway, Galway, Ireland
c School of Chemical Sciences, Dublin City Uni6ersity, Glasne6in, Dublin 9, Ireland
Received 7 May 2001; accepted 27 August 2001
This paper is dedicated to Professor Kees Vrieze, a good friend and an excellent chemist
Abstract
The iron hydrido complex HFe(CO)2{P(OPh)3}{(PhO)2POC6H4} (1), was rapidly deprotonated by DBU or [BzMe3N][OH] in
THF to afford the new carbonyl iron anion [Fe(CO)2{P(OPh)3}{(PhO)2POC6H4}]− ([2]−), containing an ortho-metallated
triphenyl phosphite ligand. Complex [2]− reacted with triorganostannyl and plumbyl salts and with halogens to give the
octahedral FeII compounds Fe(CO)2{P(OPh)3}{(PhO)2POC6H4}(X) (X=SnPh3, 3; SnMe3, 4; PbPh3, 5; PbMe3, 6; Cl, 7; Br, 8; I,
9). The Group 14 complexes 3–6 were obtained in one isomeric form in which the PIII-donor atoms are mutually cis, the carbonyl
ligands are cis and the P(OPh)3 and MR3 (M=Sn, Pb; R=Ph, Me) groups are trans as determined by solution-state IR, 31P and
13C NMR spectroscopic data. This geometry was confirmed for 3 by a single crystal X-ray diffraction study. The halide
complexes, however, were obtained as a mixture of isomers. The major isomer (7, X=Cl; 8a, X=Br; 9a, X=I) has cis P atoms,
trans CO groups and the halide located trans to the phosphorus atom of the ortho-metallated phosphite ligand. The structure of
9a was confirmed by an X-ray diffraction study. Two other isomers, designated 8b (X=Br) and 9b (X=I), with cis P atoms and
cis CO groups were isolated from the reactions of [2]− with Br2 and I2, respectively. The structure of the latter was established
by X-ray crystallography and is related to 9a by exchange of the P(OPh)3 ligand and a carbonyl group such that the metal-bound
C atom of the five-membered metallacycle is trans to CO. The stereo-geometry of 8b could not be unambiguously assigned from
the spectroscopic data; however, two of the seven possible geometric isomers were suggested as plausible structures. © 2002
Elsevier Science B.V. All rights reserved.
Keywords: Crystal structures; Iron complexes; Ferrate anion complexes; Phosphite complexes; Tin complexes; Lead complexes
nucleophilicity of the iron centre in the above com-
plexes is increased on substitution of CO by phospho-
1. Introduction
rus-donor ligands; the mono-anions [HFe(CO)3−n
-
Metal-centred anions are versatile nucleophiles with
applications in both organometallic and organic synthe-
sis. In this context the iron carbonyl metallates are
especially important, the best known being the commer-
cially available Collman’s reagent [Fe(CO)4]2− and its
conjugate acid the hydrido-anion [HFe(CO)4]−. The
(PR3)n]− (n=1, 2) have been reported [1–3] and their
reactivity investigated [3–5].
In a series of recent papers we have explored the
chemistry of the cyclometallated iron hydrido complex
HFe(CO)2{P(OPh)3}{(PhO)2POC6H4} (1) [6,7], which
is obtained on photolysis of the bis(phosphite) complex
Fe(CO)3{P(OPh)3}2 [8]. Here we describe some reac-
tions of the carbonylferrate derived from 1:
[Fe(CO)2{P(OPh)3}{(PhO)2POC6H4}]− ([2]−).
* Corresponding author. Fax: +353-1-716 2127.
E-mail address: anthony.manning@ucd.ie (A.R. Manning).
0020-1693/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved.
PII: S0020-1693(01)00693-4

D. Courtney et al. / Inorganica Chimica Acta 327 (2002) 98–107
99
2. Experimental
[HDBU][2] was used directly in subsequent reactions
assuming a 100% yield.
2.1. General methods
2.2.2. General procedure for the preparation of
Fe(CO)2{P(OPh)3}{(PhO)2POC6H4}(X) (X=SnPh3, 3;
SnMe3, 4; PbPh3, 5; PbMe3, 6; Cl, 7; Br, 8a,b; I,
9a,b)
The complex Fe(CO)3{P(OPh)3}2 was prepared as
described previously [6]. Pyridinium hydrobromide per-
bromide (C5H5NH+Br3−) [9] and iodobenzene dichlo-
ride (PhICl2) [10] were employed as convenient sources
of Br2 and Cl2, respectively, and were prepared accord-
ing to the literature methods. Other reagents including
I2 and the triorganotin and lead salts R3SnCl (R=Ph,
Me), Ph3PbCl and Me3PbOAc were purchased and
used without further purification. All reactions were
carried out at room temperature under an atmosphere
of nitrogen in dried and deoxygenated solvents. IR
spectra were recorded on a Perkin–Elmer Paragon
1000 FTIR spectrometer. 13C{1H} NMR spectra were
obtained at 25 °C on a JEOL 270 MHz spectrometer
operating at 67.9 MHz and were referenced to internal
A stoichiometric quantity of the appropriate elec-
trophile was added to a solution of [HDBU][2] in THF,
prepared as described above, and the resulting mixture
was stirred at room temperature for approximately
30–45 min. The reaction mixtures were filtered through
a pad of alumina to remove precipitated salts and any
decomposition products. The filtrate was concentrated
and recrystallisation from CH2Cl2–hexane mixtures af-
forded complexes 3–6. The halide derivatives, 7–9,
were purified by column chromatography on silica:
elution with CH2Cl2–hexane (1:1) and subsequent re-
crystallisation from CH2Cl2–hexane afforded the iso-
mers 7, 8a and 9a, respectively; elution with
CH2Cl2–hexane (4:1) afforded a second material from
which the isomers 8b and 9b, respectively, were ob-
tained after recrystallisation from CH2Cl2–hexane.
The yields, melting points, analyses and IR spectro-
scopic data of these complexes are collected in Table 1;
31P{1H} and selected 13C{1H} NMR spectroscopic data
are presented in Table 2.
1
CDCl3. H and 31P{1H} NMR spectra were obtained at
30 °C on a Varian INOVA 300 MHz spectrometer
operating at 300 and 121.4 MHz, respectively, and were
referenced to internal TMS and external H3PO4 in D2O,
respectively. Analyses were determined by the Analyti-
cal Laboratory, University College Dublin.
2.2. Syntheses
2.3. Crystal structure determinations of complexes 3,
9a and 9b
2.2.1. Preparation of [HDBU][Fe(CO)2{P(OPh)3}-
{(PhO)2POC6H4}] ([HDBU][2])
A stirred solution of Fe(CO)3{P(OPh)3}2 (0.500 g,
0.66 mmol) in THF (50 ml) was cooled in an ice-water
bath and irradiated with a 125 W mercury vapour lamp
until the starting material was consumed (typically 1–2
h) as determined by IR spectroscopy. A slight excess of
1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) (0.11 ml, 0.67
mmol) was added and the mixture was allowed to stir
for approximately 2 min. The resulting solution of
X-ray quality single crystals of 3, 9a and 9b were
grown from toluene–hexane solutions. X-ray data were
collected on a Bruker P4 diffractometer (Mo Ka radia-
,
tion, u=0.71073 A) at 294(2) K. The structures were
solved by direct methods SHELXS97 and refined by
full-matrix least-squares using SHELXL97 [11]. There is
no disorder in the stannyl derivative 3. In 9a, a phenoxy
group {C61, …, C66} is disordered over two sites with
Table 1
Yields, melting points, analyses and IR spectroscopic data for compounds Fe(CO)2{P(OPh)3}{(PhO)2POC6H4}(X) (3–9)
a
Compound
Yield (%)
M.p. (°C)
Analysis
%C
IR spectra b
X
%H
Other
w(CO)
3
4
5
6
SnPh3
SnMe3
PbPh3
PbMe3
Cl
Br
Br
I
I
41
51
55
51
60
20
10
48
20
178
149–151
155
147–149
130–132
146–148
149–150
153
62.3 (62.5)
54.7 (55.0)
56.1(57.5)
50.1 (49.5)
59.4 (59.5)
56.2 (56.3)
55.4 (56.3)
52.9 (53.2)
53.3 (53.2)
3.5 (3.7)
4.1 (4.3)
3.7 (3.8)
3.9 (3.8)
3.8 (3.8)
3.7 (3.6)
3.5 (3.6)
3.4 (3.5)
3.3 (3.5)
P 5.5 (5.7)
P 7.0 (6.9)
P 5.0 (5.3)
P 6.3 (6.2)
Cl 4.8 (4.6)
Br 9.7 (9.9)
Br 12.7 (9.9)
I 14.2 (14.8)
I 14.6 (14.8)
2019 (10), 1975 (8.9)
2007 (10), 1963 (8.7)
2018 (10), 1978 (9.2)
2006 (10), 1964 (8.7)
2064 (1.0), 2026 (10)
2022
2064 (10), 2022 (8.4)
2018
2052 (10), 2012 (9.9)
7
8a
8b
9a
9b
139–140
a Found with calculated values in parentheses.
b Spectra recorded in dichloromethane; peak positions in cm−1 with relative peak heights in parentheses.

Table 2
31P{1H} and selected 13C{1H} NMR spectroscopic data for Fe(CO)2{P(OPh)3}{(PhO)2POC6H4}(X) (3–9)
Compound
X
31P NMR a
P1
13C NMR a
CO
P2
CO
C1
C2
C3
C4/C5
C6
3
SnPh3
185.9 (d,
147.3 (d,
214.1 (dd,
211.2 (dd,
2JCP=31.8,
12.4)
211.6 (dd,
2JCP=32.8,
10.4)
210.0 (dd,
2JCP=31.8,
12.4)
211.6 (dd,
2JCP=32.6,
11.3)
139.8 (dd,
2JCP=27.6,
22.9)
161.5 (dd,
113.4 (d,
125.9 (s); 123.7 145.2 (d,
(d, JCP=3.3)
3JCP=4.3)
2JPP=68.7,
2JPSn=339, 356) b
188.0 (d,
2JPP=68.7,
2JPSn=533, 557)
150.4 (d,
2JCP1=60.9,
2JCP2=22.1)
215.1 (dd,
2JCP1=25.6,
3JCP2=3.4)
160.6 (dd,
3JCP1=16.2)
c
4
SnMe3
142.6 (m,
111.9 (dd,
obscured; 123.2 142.6 (s)
(d, JCP=2.7)
2JPP=57.4,
2JPSn=277, 290)
183.5 (d,
2JPP=57.4,
2JPSn=426, 446)
149.3 (d,
2JCP1=62.1,
2JCP2=19.0)
212.3 (dd,
obscured by C6) 2JCP1=26.4,
3JCP1=17.3,
4JCP2=3.2)
113.2 (dd,
3JCP2=3.4)
/
5
PbPh3
139.3 (dd,
2JCP=28.5,
25.3)
160.9 (dd,
125.5 (s); 123.4 144.0 (s)
(d, JCP=2.2)
2JPP=70.7,
2JPPb=552)
187.2 (d,
2JPP=70.7,
2JPPb=970)
150.1 (d,
2JCP1=62.4,
2JCP2=22.6)
214.2 (dd,
2JCP1=25.8,
3JCP2=2.2)
160.3 (dd,
3JCP1=16.2,
4JCP2=2.1)
111.9 (d,
d
6
PbMe3
142.8 (m,
124.6 (s); 123.2 142.5 (s)
(s)
2JPP=56.8,
2JPPb=435)
188.0 (d,
2JPP=56.8,
2JPPb=723)
147.9 (d,
2JCP1=64.1,
2JCP2=8.7)
obscured by C6) 2JCP1=27.0,
3JCP2=2.3)
3JCP1=16.7)
7
Cl
Br
Br
I
206.7 (dd, 2JCP=34.8, 22.1)
135.5 (dd,
160.5 (d,
112.1 (d,
126.9 (s); 124.7 140.4 (s)
(s)
2JPP=84.7)
2JPP=84.7)
2JCP2=41.7,
2JCP1=18.1)
134.5 (dd,
2JCP1=16.7)
3JCP1=13.8)
8a
8b
9a
9b
191.5 (d,
148.0 (d,
207.1 (dd, 2JCP=33.7, 21.6)
160.3 (d,
112.1 (d,
126.9 (s); 125.0 142.5 (s)
(d, JCP=2.5)
327
2JPP=88.3)
2JPP=88.3)
2JCP2=40.0,
2JCP1=18.1)
146.0 (dd,
J
CP1=16.7)
3JCP1=13.8)
(
173.6 (d,
157.3 (d,
209.3 (dd,
205.1 (dd,
2JCP=28.0,
20.5)
160.7 (d,
CP1=23.6)
113.4 (d,
126.8 (s); 124.4 142.6 (d,
2JPP=126.3)
2JPP=126.3)
2JCP=82.8,
2JCP=32.3)
JCP=38.7, 25.8)
J
J
CP=16.2)
(s)
3JCP=2.1)
9
107
194.3 (d,
151.4 (d,
208.3 (dd, 2JCP=31.8, 21.0)
133.4 (dd,
159.9 (d,
112.2 (d,
127.0 (s); 125.2 146.5 (s)
(s)
2JPP=91.8)
2JPP=91.8)
2JCP2=36.7,
2JCP1=17.7)
134.2 (dd,
2JCP1=16.9)
3JCP1=13.3)
I
196.1 (d,
137.0 (d,
208.3 (dd,
205.2 (dd,
2JCP=27.4,
22.1)
161.2 (dd,
112.3 (dd,
127.3 (s); 124.9 147.5 (s)
(s)
2JPP=112.4)
2JPP=112.4)
2JCP2=88.1,
2JCP1=29.0)
J
CP=41.4, 21.0) 2JCP1=20.5,
3JCP1=2.1,
4JCP2=16.1)
3JCP2=3.3)
a Spectra recorded in CDCl3 solution; chemical shifts in ppm with multiplicities and coupling constants J in Hz in parentheses.
b The ratio of the coupling constants is equal to that of the gyromagnetic ratio of 117Sn and 119Sn.
c NMR data for the CH3 group: lH 0.09 (s, 2JHSn=46 Hz) and lC −4.30 (d, 3JCP=3.5 Hz, 1JCSn=245 Hz).
d NMR data for the CH3 group: lH 0.64 (s, 2JHPb=38 Hz) and lC 1.81 (d, 3JCP=5.4 Hz, 1JCPb=45 Hz).

D. Courtney et al. / Inorganica Chimica Acta 327 (2002) 98–107
101
Table 3
Summary of crystal data and details of the data collection and refinement for 3, 9a and 9b
Complex
3
9a
9b
Empirical formula
Molecular weight
Colour, habit
Crystal size (mm)
Crystal system
Space group
C56H44FeO8P2Sn
1081.39
colourless, block
0.30×0.20×0.10
monoclinic
P21/c
C
858.30
red–brown, block
0.38×0.34×0.28
monoclinic
P21/c
38H29FeIO8P2
C38H29FeIO8P2
858.30
red–brown, block
0.38×0.35×0.18
monoclinic
P21/a
,
a (A)
15.4221(14)
16.3298(17)
20.798(3)
108.794(7)
4958.5(9)
4
1.449
0.916
2200
10.3570(13)
17.9450(13)
19.7551(18)
90.510(9)
3671.5(6)
4
1.553
1.390
17.6772(13)
10.5650(11)
20.363(2)
102.629(6)
3711.0(6)
4
1.536
1.375
,
b (A)
,
c (A)
i (°)
V (A )
3
,
Z
Dcalc (Mg m−3
)
v (mm−1
F(000)
)
1720
1720
q Range for data collection (°) 2–28
2–28
2–28
hkl range
−1 to 20, −1 to 21, −27 to 24
−1 to 13, −1 to 23, −26 to 26
−1 to 23, −1 to 13, −26 to 26
Rint
0.057
0.019
0.037
Completeness to 2q
Max/min transmission
Reflections collected
Unique reflections
Reflections with I\2|(I)
Data/restraints/parameters
Goodness-of-fit on F2
Final R1 indices [I\2|(I)]
wR2 [I\2|(I)]
100% (52°)
0.914, 0.771
13 369
11 357
5313
11 357/0/614
0.99
0.068
100% (56°)
0.70, 0.624
10 819
8775
6928
8775/2/482
1.04
100% (56°)
0.790, 0.623
10 649
8818
5390
8818/98/482
1.03
0.050
0.035
0.086
0.084
0.102
R1 indices (all data)
0.176
0.051
0.096
wR2 (all data)
Final D-map (e A
0.108
0.58, −0.42
0.093
0.72, −0.30
0.119
0.74, −0.47
−3
,
)
s.o.f.s of 0.59(3)/0.41(3); in 9b, the phenoxy group
{C21, …, C26} is disordered over two sites which were
treated as rigid hexagons with s.o.f.s of 0.606(10)/
0.394(10). Details of the X-ray data collections and
structure refinements are summarised in Table 3.
ion [Fe(CO)2{P(OPh)3}{(PhO)2POC6H4}]− (Scheme 1,
showing one possible isomeric structure for each of 1
and [2]−). The reaction is accompanied by a colour
change from orange to light yellow and by the antici-
pated shift to lower frequency of the w(CO) bands in
the IR spectrum {w(CO) 1: 2034 and 1984 cm−1; w(CO)
[HDBU][2]: 1929 and 1860 cm−1}. Upon addition of 1
equiv. of HBF4, the hydrido complex, 1, is re-formed,
as determined by IR spectroscopy. Unfortunately, at-
tempts to isolate [2]− in the solid state, as its PPN or
R4N salt, have not been successful and its solutions in
THF have therefore been used directly in all subsequent
reactions.
3. Results and discussion
3.1. Formation of 1 and 2
The precursor iron hydrido complex employed in this
study was prepared as previously reported [8]: UV-irra-
diation of Fe(CO)3{P(OPh)3}2 proceeds with CO loss
and intramolecular C–H activation to afford
HFe(CO)2{P(OPh)3}{(PhO)2POC6H4} (1), in which the
hydrido ligand derives from oxidative addition of an
ortho-C–H moiety of a phenoxy group to the iron
centre. Complex 1 is obtained as an oil which it has not
proved possible to crystallise; it has been used in situ
for further reactions. Complex 1 is an acid; it reacts
slowly (ca. 2–3 h) with RLi (R=Me, Bu) and rapidly
(ca. 2–3 min) with DBU or [BzMe3N][OH] to afford a
new species, [2]−, which we formulate as the mono-an-
Scheme 1. Synthesis of 1 and [2]−
.

102
D. Courtney et al. / Inorganica Chimica Acta 327 (2002) 98–107
However, the products derived from reaction with or-
ganic electrophiles such as RI (R=Me, Et) and
MeC(O)Cl, have not proved isolable. The stable com-
pounds described below have been obtained from the
reactions of [2]− with some inorganic electrophiles.
They comprise two classes: stannyl and plumbyl deriva-
tives obtained from reaction with triorganotin and lead
salts; and halide complexes derived from reaction with
halogens. An important feature of these compounds is
the potential existence of a number of isomeric forms.
Given the cis geometry imposed on the ligating atoms
of the metallacycle, a total of seven geometric isomers
are possible in these six-coordinate complexes. These
are illustrated in Fig. 1 and designated A–G.
3.2.1. Reaction with R3MY (M=Sn, Pb; Y=Cl,
OAc)
The triorganotin and lead salts R3SnCl (R=Ph,
Me), Ph3PbCl and Me3PbOAc reacted with [Fe(CO)2-
{P(OPh)3}{(PhO)2POC6H4}]− within 30 min to afford
the expected products Fe(CO)2{P(OPh)3}{(PhO)2-
POC6H4}(MR3) (M=Sn, R=Ph, 3; R=Me, 4; M=
Pb, R=Ph, 5; R=Me, 6). These were isolated in yields
of approximately 40–60% as pale yellow (R=Ph) or
deep yellow (R=Me) crystalline compounds. For each
of the complexes 3–6, a single isomer was obtained.
Since these compounds contain the NMR spin-active
nuclei Sn or Pb, an unambiguous assignment of the
solution-state geometry was possible from analysis of
the 31P and 13C NMR spectroscopic data (Table 1). The
31P{1H} NMR spectra of 3–6 exhibit two doublet
resonances (2JPP ca. 57–72 Hz) centred at approxi-
mately l 185 and 147 with satellite peaks arising from
coupling to 119Sn and 117Sn (3, 4) or 207Pb (5, 6). The
spectrum of complex 3 is reproduced in Fig. 2 as a
representative example. The low-field signal at approxi-
mately l 185 is assigned to the phosphorus atom P1 of
the ortho-metallated (PhO)2POC6H4 moiety: compared
to related acyclic systems the NMR signal of phospho-
rus in a five-membered metallacycle is shifted 20–50
ppm downfield [12]. The magnitude of the 31P–31P
coupling constants establishes a cis relationship be-
tween P1 and P2 (trans coupling between 31P nuclei in
this system is of the order of 300–350 Hz) and the
magnitude of the 31P–M (M=117/119Sn or 207Pb) cou-
pling constants establishes a trans relationship between
P2 and M. The carbonyl region of the 13C{1H} NMR
spectra of 3–6 (that of 3 is shown in Fig. 3) comprises
two doublet of doublet resonances consistent with two
inequivalent CO groups each coupled to two inequiva-
Fig. 1. Possible geometric isomers of Fe(CO)2{P(OPh)3}-
{(PhO)2POC6H4}(X).
Fig. 2. 31P{1H} NMR spectrum of Fe(CO)2{P(OPh)3}-
{(PhO)2POC6H4}(SnPh3) (3).
Fig. 3. Carbonyl region of the 13C{1H) NMR spectrum of
Fe(CO)2{P(OPh)3}{(PhO)2POC6H4}(SnPh3) (3).
3.2. Reaction of [2]− with electrophiles
2
lent P nuclei. Inspection of the JCP couplings discloses
The carbonylferrate anion, [2]−, is a versatile nucle-
ophile and reacts smoothly with diverse electrophiles to
afford complexes, the IR spectra of which are consis-
tent with the formulation Fe(CO)2{P(OPh)3}{(PhO)2-
POC6H4}(X) where X is a one-electron donor ligand.
a trans arrangement of a CO group and a P ligand,
which must necessarily be P1. The solution-state ge-
ometry of compounds 3–6 is therefore type D in Fig. 1.
It is interesting to compare the above compounds
with the related six-coordinate stannyl derivatives

D. Courtney et al. / Inorganica Chimica Acta 327 (2002) 98–107
103
HFe(CO)2{P(OPh)3}2(SnR3) (R=Me, Ph) prepared by
Schubert and co-workers on addition of HSnR3 to the
hydrido complex 1 [13]. These complexes exhibit tem-
perature-dependent isomeric forms: at room tempera-
ture the carbonyl ligands are mutually trans and the
triphenyl phosphite groups are cis; at −40°C a second
isomeric form was detected which has cis CO and trans
phosphite ligands. There is no evidence for similar
isomer interconversions in 3–6.
NMR spectroscopy of the filtrates revealed further
isomers but these were not isolated in sufficient quan-
tity to permit full characterisation.
Under the conditions employed, the major isomer
isolated (7, Cl; 8a, Br; 9a, I) was of structure C (Fig. 1)
in which the PIII-donor atoms are mutually cis and the
carbonyl groups mutually trans. This assignment again
follows directly from the solution-state spectroscopic
data in Tables 1 and 2: the magnitude of the JPP
coupling constants (85–92 Hz) establishes the cis rela-
tionship of the phosphorus nuclei; the single intense
absorption band in the w(CO) region of the IR spectra
indicates that the CO ligands are trans and this is
confirmed by the observation of a single l(CO) reso-
nance in the 13C NMR spectrum. The w(CO) and
l(CO) values show the expected dependence on the
electronegativity of the halide substituent, the former
decreasing and the latter increasing along the series 7,
8a and 9a. The 31P NMR chemical shifts of the P1 and
P2 nuclei follow the same trend as the l (CO) values.
The minor isomers 8b (X=Br) and 9b (X=I) were
obtained analytically pure and in sufficient quantity for
full spectroscopic characterisation from the reactions of
[2]− with bromine and iodine, respectively. Both com-
plexes contain cis PIII ligands (JPP=126 and 112 Hz,
respectively) as well as cis carbonyl groups as deter-
mined by IR and 13C NMR spectroscopy (Tables 1 and
2). In the absence of further NMR coupling informa-
tion it was not possible to assign unambiguously the
geometry of either of these complexes. However, the
structure of the iodo derivative, Fe(CO)2{P(OPh)3}-
{(PhO)2POC6H4}(I) (9b), has been established by single
crystal X-ray diffraction analysis (see Section 3.3). The
solid-state geometry is E (Fig. 1) and the solution-state
spectroscopic data are consistent with this stereochem-
istry.
The 13C NMR chemical shifts of the ortho-metallated
aryl ring carbons C1–C6 (atoms designated as in Fig.
1) are given in Table 2. These values span a range of
approximately 50 ppm and their assignment follows
from that of Stewart and co-workers for the related
complexes Fe(h5-C5H5)(L){(PhO)2POC6H4} [L=CO,
P(OPh)3] [14]. Thus, the directly metal-bound carbon
atom C1 is attributed to a low-intensity resonance at
approximately 139–143 ppm. For the phenyl deriva-
tives, 3 and 5, this signal appears as a doublet of
doublets due to two-bond coupling to the cis phospho-
rus nuclei, P1 and P2; for the methyl analogues, 4 and
6, the signal is obscured by that due to C6, and reliable
extraction of the J values was not possible. The carbon
atom C2, directly bonded to the O atom, is strongly
deshielded and its 13C NMR resonance appears at
approximately l 160 (contrasting with a value of ca. l
151 for the ipso-carbon atoms of the unmetallated
phenoxy rings). Two-bond coupling to P1 of approxi-
mately 26 Hz and a much weaker (ca. 3 Hz) three-bond
coupling to P2 result in a doublet of doublet pattern for
this resonance. Three- and four-bond coupling to P1
and P2, respectively, also account for the multiplicity of
the signal attributed to C3, which is shifted some 15 Hz
to higher field than the ortho-carbon atoms of the
unmetallated rings. It is not possible to assign defini-
tively the remaining ring atoms C4 and C5 to the
resonances at approximately 125 and 123. However, the
latter signal consistently appears as a doublet, exhibit-
ing a small 13C–31P coupling of 2–3 Hz, or as a slightly
broadened singlet where coupling is not resolvable. We
tentatively assign this resonance to C4 and invoke a
weak, long-range ‘W-coupling’ of C4 and P1 to account
for the observed signal splitting.
Comparison of the 31P NMR chemical shift data of
8b and 9b suggests that these complexes do not have
the same geometry if, as noted above for the trans-CO
isomers 8a and 9a, the l(P) values are expected to shift
regularly to lower field on progressing from the bromo
to the iodo derivative. Examination of the 13C–31P
coupling constants from the 13C NMR spectrum of 8b
indicates that only one CO ligand experiences a large
(JCP=82.8 Hz) trans coupling to a phosphorus nucleus.
The geometry of isomer 8b is therefore either D or F.
3.2.2. Reaction with halogens
The iron–halide complexes Fe(CO)2{P(OPh)3}-
{(PhO)2POC6H4}(X) (X=Cl, 7; Br, 8; I, 9) were ob-
tained as yellow (X=Cl) or red–brown (X=Br, I)
solids on reaction of [2]− with the halogens or their
synthetic equivalents, pyridinium hydrobromide per-
bromide (C5H5NH+Br3−) and iodobenzene dichloride
(PhICl2). In marked contrast to the above Group 14
derivatives, the halide complexes were obtained as a
mixture of geometric isomers. Separation of some of
these isomers was achieved by column chromatography
and fractional crystallisation; analysis by IR and 31P
Unfortunately, the 13C–31P coupling constants (JCP
=
38.7, 25.8 Hz) experienced by the metal-bound carbon
atom C1 do not unambiguously establish whether or
not this nucleus is trans to a phosphorus atom and
further distinction between isomers D and F was not
possible in this case. The stereo-geometries assigned to
the iron–halide complexes 7–9 are summarised in Fig.
4 for clarity.

104
D. Courtney et al. / Inorganica Chimica Acta 327 (2002) 98–107
Fig. 4. Geometries of the iron–halide complexes 7–9.
derivative 3). This presumably reflects the contraction
expected in the bonding parameters of the P1 ligand
upon ortho-metallation.
3.3. Crystal and molecular structures of 3, 9a and 9b
The crystal and molecular structures of the triphenyl-
stannyl derivative 3, Fe(CO)2{P(OPh)3}{(PhO)2-
POC6H4}(SnPh3), and the two isomeric iodo complexes
9a and 9b, Fe(CO)2{P(OPh)3}{(PhO)2POC6H4}(I) have
been determined. Their molecular structures are de-
picted in Figs. 5–7, respectively, and selected molecular
parameters are given in Table 4. The solid-state ge-
ometries of 3 and 9a are the same as those deduced
above from the solution-state spectroscopic data.
3.3.1. Molecular structures of 3, 9a and 9b
The coordination sphere about the FeII atoms is
approximately octahedral in each of 3, 9a and 9b, but
the deviations from ideal Oh symmetry are marked. The
extent of these distortions may be illustrated by the
following trans-angles: P2ꢀFe1ꢀSn1 in 3, 164.64(6)°;
C1ꢀFe1ꢀC2 in 9a, 162.83(13)°; and P2ꢀFe1ꢀC1 in 9b,
163.12(15)°. The main feature of these structures is the
five-membered metallacycle ring MPOC6H4 derived
from ortho-metallation of a phenoxy group of a
triphenyl phosphite ligand. These are the first struc-
turally characterised examples of this moiety where
M=Fe although a number of related complexes with
M=Ru are known [15]. The metallacycles are almost
planar: the Fe1 atom deviates from co-planarity with
Fig. 5. Molecular structure of Fe(CO)2{P(OPh)3}{(PhO)2-
POC6H4}(SnPh3) (3).
,
the {C11, …, C16} ring by 0.082(9) A towards the Sn1
,
atom in 3; by 0.012(4) A on the C2ꢀO2 side in 9a; and
,
by 0.055(6) A on the P2 side in 9b. The angles
P1ꢀFe1ꢀC11 subtended at the iron atom by the ortho-
metallated phosphite ligands are similar in all three
complexes and in the range 80.47(11)–81.70(8)°. These
values are approximately 2–4° larger than the corre-
sponding angles of 77.5(2) and 79.2(2)° for the same
ligand in the Ru complex Ru{P(OPh)3}2{(PhO)2-
POC6H4}2 [15a], presumably reflecting the smaller size
of the first row transition metal. The necessarily con-
strained bite angle of the chelate ligand is considered to
be the ultimate source of the distortions from octahe-
dral geometry exhibited by 3 and 9a, b.
The PIII-donor atoms adopt mutually cis positions in
all three structures. The FeIIꢀP bond lengths are in the
normal range for such bonds [16], but the Fe1ꢀP1
distances in each of 3, 9a and 9b are consistently
shorter than the Fe1ꢀP2 bond lengths (although this
difference is not statistically significant in the stannyl
Fig. 6. Molecular structure of trans-Fe(CO)2{P(OPh)3}{(PhO)2-
POC6H4}(I) (9a).

D. Courtney et al. / Inorganica Chimica Acta 327 (2002) 98–107
105
different types of FeꢀCO interaction in the two isomers:
CO trans to CO in 9a [average FeꢀC=1.81, CꢀO=
,
1.13 A]; CO trans to phosphorus in 9b [FeꢀC1=
,
1.811(5), C1ꢀO1=1.108(5) A]; and CO trans to carbon
,
[FeꢀC2=1.803(5), C2ꢀO2=1.144(5) A]. The data indi-
cate that the trans-influence of the triphenyl phosphite
ligand on CO is not substantially different to that of
CO itself and that, contrary to the expected strong
trans-effect of h1-aryls, the ortho-metallated ligand
does not significantly destabilise the FeꢀCO interaction.
The most interesting difference between the two iso-
meric structures lies in the considerable lengthening
of both the FeꢀP and FeꢀI distances in 9b when com-
pared to the trans complex 9a. This increase is also
reflected in the greater unit cell volume of the former
complex.
Fig. 7. Molecular structure of cis-Fe(CO)2{P(OPh)3}{(PhO)2-
POC6H4}(I) (9b).
Table 4
,
Selected bond lengths (A) and angles (°) for 3 (X=SnPh3), 9a (X=I)
and 9b (X=I)
3
9a
9b
,
The Fe1ꢀSn1 bond length of 2.6251(9) A in 3 is at
the longer end of the range known for such bonds. It
Fe1ꢀX
2.6251(9)
2.1543(19)
2.1649(18)
1.768(7)
1.775(7)
2.040(6)
1.605(4)
1.591(4)
1.608(4)
1.615(4)
1.603(4)
1.593(4)
1.161(6)
1.143(7)
2.6485(4)
2.1262(8)
2.2013(8)
1.808(3)
1.812(3)
2.063(3)
1.608(2)
1.598(2)
1.587(2)
1.595(2)
1.600(2)
1.604(2)
1.136(3)
1.126(3)
2.6646(6)
2.1435(11)
2.2201(12)
1.811(5)
1.803(5)
2.070(4)
1.590(3)
1.598(3)
1.590(3)
1.595(3)
1.572(3)
1.598(3)
1.108(5)
1.144(5)
may be compared with a (shortest recorded) FeꢀSn
Fe1ꢀP1
Fe1ꢀP2
Fe1ꢀC1
Fe1ꢀC2
Fe1ꢀC11
P1ꢀO11
P1ꢀO21
P1ꢀO31
P2ꢀO41
P2ꢀO51
P2ꢀO61
O1ꢀC1
O2ꢀC2
,
distance of 2.408(1) A in the trigonal bipyramidal stan-
nylene complex Fe(CO)4{Sn(OC6H2But2-2,6-Me-4)2}
5
,
[17]; with 2.537(3) A in Fe(h -C5H5)(CO)2(SnPh3) [18];
and with 2.655(1) and 2.666(1) A in the crowded octa-
,
hedral complex Fe(CO)4(SnPh3)2 [19].
The geometry about the Sn1 atom is approximately
tetrahedral and the tin–carbon distances [Sn1ꢀC71,
2.172(6); Sn1ꢀC81, 2.163(6); Sn1ꢀC91, 2.157(6) A] are
as expected. Interestingly, there is distortion about the
CipsoꢀSn1ꢀCipso bonds, which vary from 99.9(2)° for
C71ꢀSn1ꢀC91 to 107.3(3)° for C71ꢀSn1ꢀC81. Some
distortion is also present in the Sn1ꢀCipsoꢀCortho angles,
with the greatest difference being approximately 10° for
Sn1ꢀC91ꢀC96 [116.9(5)°] compared with Sn1ꢀC91ꢀC92
[127.3(5)°] and probably due to the intramolecular con-
,
P1ꢀFe1ꢀP2
P1ꢀFe1ꢀX
P2ꢀFe1ꢀX
97.16(7)
84.46(5)
164.64(6)
92.6(2)
169.4(2)
81.19(17)
103.1(2)
91.2(2)
84.58(16)
91.8(3)
170.8(3)
93.2(3)
94.83(3)
176.49(3)
88.05(2)
90.63(9)
95.59(9)
81.70(8)
100.43(9)
94.98(9)
176.38(8)
162.83(13)
80.71(11)
84.37(12)
86.87(8)
86.14(9)
95.45(8)
172.5(3)
176.2(3)
100.96(11)
104.92(11)
99.47(11)
108.68(8)
127.09(8)
113.27(7)
96.19(4)
174.38(4)
87.94(3)
90.74(15)
97.90(15)
80.47(11)
163.12(15)
98.75(15)
82.71(11)
95.5(2)
83.29(18)
177.94(19)
84.28(15)
85.20(15)
96.32(10)
178.0(4)
P1ꢀFe1ꢀC1
P1ꢀFe1ꢀC2
P1ꢀFe1ꢀC11
P2ꢀFe1ꢀC1
P2ꢀFe1ꢀC2
P2ꢀFe1ꢀC11
C1ꢀFe1ꢀC2
C1ꢀFe1ꢀC11
C2ꢀFe1ꢀC11
XꢀFe1ꢀC1
,
tact
C92ꢀH92···O2
(H92···O2=2.71
A
and
C92ꢀH92···O2=110°) resulting in the Sn1ꢀC91ꢀC92
angle opening up to 127°.
The Fe1ꢀI1 bond distances of 2.6485(4) and
2.6646(6) A in 9a and 9b, respectively, both fall in the
,
91.6(2)
83.8(2)
mid-range of the values usually found [16]. They are
XꢀFe1ꢀC2
considerably longer than the FeꢀI distance of 2.618(6)
XꢀFe1ꢀC11
Fe1ꢀC1ꢀO1
Fe1ꢀC2ꢀO2
O11ꢀP1ꢀO21
O11ꢀP1ꢀO31
O21ꢀP1ꢀO31
O11ꢀP1ꢀFe1
O21ꢀP1ꢀFe1
O31ꢀP1ꢀFe1
81.23(15)
176.0(6)
176.3(6)
104.8(2)
96.2(2)
102.6(2)
108.84(16)
115.22(17)
125.95(18)
,
A
in the phosphite complex Fe(CO)2(CH2I)-
{P(OPri)3}2(I) [20], but shorter than the values in the
174.3(4)
isomeric phosphine derivatives cis-,trans-Fe(CO)2-
(PMe3)2(CH3)(I) [FeꢀI=2.695(1) A] and trans-,trans-
Fe(CO)2(PMe3)2(CH3)(I) [FeꢀI=2.681(1) A] [21]. In
both 9a and 9b the I atoms are located trans to P1.
Following the analysis developed by Cardaci and co-
workers in Ref. [21], we note that there are three
104.21(19)
95.08(16)
103.48(19)
109.40(11)
112.18(13)
129.03(14)
,
,

106
D. Courtney et al. / Inorganica Chimica Acta 327 (2002) 98–107
3.3.2. Crystal structures of 3, 9a and 9b
The principal intermolecular interaction in the crystal
structure of the stannyl complex 3 is C14ꢀH14···O1i
(symmetry operator i=x, 1/2−y, −1/2+z) with
i
i
,
H14···O1 =2.59 A and a C14ꢀH14···O1 angle of 138°
(all aromatic CꢀH bond lengths are the SHELXL97
defaults, 0.93 A). There are two important intramolecu-
lar CꢀH···p(arene) hydrogen bonds: (a) C52ꢀH52···
p{C61, …, C66} with H52···p(centroid)=2.74 A and a
C52ꢀH52···p(centroid) angle of 142°; and (b)
C46ꢀH46···p{C31, …, C36} with H46···p(centroid)=
2.80 A and a C46ꢀH46···p(centroid) angle of 143°.
These interactions are depicted in Fig. 8. Other inter-
,
,
,
molecular CꢀH···p(arene) interactions complete the
crystal packing e.g. (c) C33ꢀH33···p{C41, …, C46}ii
ii
,
(ii=2−x, −y, 2−z) with H33···p(centroid) =2.95 A
and C33ꢀH33···p(centroid)ii=126° and (d) C54ꢀ
H54···p{C61, …, C66}iii (iii=2−x, −1/2+y, 3/2−z)
with H54···p(centroid)iii=2.87
p(centroid)iii=143°.
A
and C54ꢀH54···
,
In the crystal structure of the iodo complex 9a there
are no significant interactions involving the iodide apart
from the intramolecular interaction C12ꢀH12···I1
Fig. 8. PLATON diagram of 3 with atoms drawn as their van der
Waal’s spheres depicting the important intramolecular CꢀH···p(arene)
interactions.
,
(H12···I1=2.91 A and C12ꢀH12···I1=126°). The most
significant CꢀH···p(arene) interaction is intermolecular
and forms a hydrogen bonded chain (Fig. 9). This is
C64AꢀH64A···p{C11, …, C16}iv (iv=1+x, y, z) with
iv
,
H64A···p(centroid) =2.74 A and a C64AꢀH64A···
p(centroid)iv angle of 151° and indicated by ¡ in Fig. 9.
This is in combination with C24ꢀH24···p{C51, …,
C56}v (v= −1+x, y, z), which orients in the opposite
direction, with H24···p(centroid)v=2.90
A
and
,
C24ꢀH24···p(centroid)v=167°, indicated by in Fig. 9.
The corresponding intramolecular interaction
C12ꢀH12···I1 involving the iodide in the crystal struc-
,
ture of 9b has H12···I1=2.93 A and C12ꢀH12···I1=
127°. The most relevant CꢀH···O interaction is
C43ꢀH43···O11vi (vi=1/2+x, 3/2−y, z) with
vi
vi
,
H43···O11 =2.55 A and C43ꢀH43···O11 =135°. Two
CꢀH···p(arene) interactions are present, one of which is
the intramolecular C52ꢀH52···p{C61,…, C66} with
,
A and C52ꢀH52···p(arene)=
H52···p(arene)=2.81
148°; the other is the intermolecular C65ꢀH65···p{C51,
…, C56}vii (vii= −x, 1−y, 1−z) interaction with
vii
vii
,
H65···p(centroid) =2.75 A and CꢀH···p(centroid) =
145°. The contact C24AꢀH24A···p(C31, …, C36}viii
(viii= −1/2−x,
−1/2+y,
−z)
[H24A···
p(centroid)viii=2.93 A and CꢀH···p(centroid)viii=169°]
further links the molecules of 9b.
,
4. Conclusions
The new carbonyl iron anion [Fe(CO)2{P(OPh)3-
{PhO)2POC6H4}]− has been shown to be a useful nu-
cleophile which reacts readily with inorganic elec-
Fig. 9. PLATON diagram of the H-bonded chain in 9a indicating the
principal CꢀH···p(arene) interactions.

D. Courtney et al. / Inorganica Chimica Acta 327 (2002) 98–107
107
trophiles to afford six-coordinate FeII complexes
Fe(CO)2{P(OPh)3{PhO)2POC6H4}(X) incorporating the
ortho-metallated triphenyl phosphite motif. The com-
plexes in which X=halide are obtained as a mixture of
isomers but those containing the larger MR3 (M=Sn,
Pb; R=Ph, Me) groups exist as a single isomer. Work
is in progress to extend the series of FeII derivatives of
[2]− and to explore the chemistry of these complexes.
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5. Supplementary material
Crystallographic data for the structural analyses have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC Nos. 163983, 163984 and 163985
for 3, 9a and 9b, respectively. Copies of this informa-
tion may be obtained free of charge from The Director,
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK
(fax:
+44-1223-336-033;
e-mail:
deposit@ccdc.
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