Synthetic, spectroscopic and structural studies of the rhenium(I) dicarbonyl complexes of phosphite, phosphonite, and phosphinite ligands: cis,mer-[ReBr(CO)2{PPh3-n(OR)n}3] (R = Me, Et; n = 1-3)

Article abstract of DOI:10.1002/zaac.200390040

The reaction of [ReBr(CO)₅] with phosphite and phosphonite ligands in toluene yielded cis,mer-[ReBr(CO)₂L₃] (2: L = P(OMe)₃ 2a: P(OEt)₃ 2b: PPh(OMe)₂ 2c: PPh(OEt)₂ 2d). Compounds 2c and 2d were also obtained, as were the phosphinite complexes 2e [L = PPh₂(OMe)] and 2f [L = PPh₂(OEt)], by reaction of the corresponding phosphorus ligand with trans,mer-[ReBr(CO)₃L₂]. Compounds 2 were all characterized by elemental analysis, mass spectrometry and NMR spectroscopy, and the structures of 2b, 2c and 2d were determined by X-ray diffractometry. Compounds 2a-d are stable in chloroform and dichloromethane, but 2e and 2f are transformed into the corresponding trans,mer[ReBr(CO)₃L₂] complexes by a reaction for which a partial mechanism is put forward.

Full text of DOI:10.1002/zaac.200390040

Synthetic, Spectroscopic and Structural Studies of the Rhenium(I) Dicarbonyl
Complexes of Phosphite, Phosphonite, and Phosphinite Ligands: cis,mer-
[ReBr(CO)2{PPh3-n(OR)n}3] (R ؍ Me, Et; n؍1؊3)
´
´
´
Rosa Carballo, Pilar Losada-Gonzalez, and Ezequiel M. Vazquez-Lopez*
´
´
Vigo, Galicia/Spain, Universidade, Departamento de Quımica Inorganica
Received September 30th, 2002.
˜
Dedicated to Professor Alfonso Castineiras on the Ocassion of his 60th Birthday
Abstract. The reaction of [ReBr(CO)5] with phosphite and phos-
phonite ligands in toluene yielded cis,mer-[ReBr(CO)2L3] (2: L ϭ
P(OMe)3 2a: P(OEt)3 2b: PPh(OMe)2 2c: PPh(OEt)2 2d). Com-
pounds 2c and 2d were also obtained, as were the phosphinite com-
plexes 2e [L ϭ PPh2(OMe)] and 2f [L ϭ PPh2(OEt)], by reaction
of the corresponding phosphorus ligand with trans,mer-
[ReBr(CO)3L2]. Compounds 2 were all characterized by elemental
analysis, mass spectrometry and NMR spectroscopy, and the struc-
tures of 2b, 2c and 2d were determined by X-ray diffractometry.
Compounds 2a-d are stable in chloroform and dichloromethane,
but 2e and 2f are transformed into the corresponding trans,mer-
[ReBr(CO)3L2] complexes by a reaction for which a partial mecha-
nism is put forward.
Keywords: Phosphorus ligands; Dicarbonyl complexes; Rhenium(I)
complexes; X-ray diffraction
Synthetische, spektroskopische und strukturelle Untersuchungen der Rhenium(I)-
dicarbonyl-Komplexe mit Phosphit-, Phosphonit- und Phosphinit-Liganden:
cis,mer-[ReBr(CO)2{PPh3-n(OR)n}3] (R ؍ Me, Et, n ؍ 1؊3)
Inhaltsübersicht. Die Reaktion von [ReBr(CO)5] mit Phosphit- und
Phosphonit-Liganden in Toluol führt zu cis,mer-[ReBr(CO)2L3] (2:
L ϭ P(OMe)3 2a, P(OEt)3 2b, PPh(OMe)2 2c, PPh(OEt)2 2d). Die
Verbindungen 2c und 2d werden auch durch Umsetzung der Phos-
phinit-Komplexe 2e [L ϭ PPh2(OMe)] und 2f [L ϭ PPh2(OEt)] mit
Elementaranalysen, Massenspektrometrie und NMR-Spektrosko-
pie charakterisiert; die Strukturen von 2b, 2c und 2d werden durch
Röntgenstrukturanalysen ermittelt. Die Verbindungen 2a؊d sind
in Chloroform und Dichlormethan stabil, doch werden 2e und 2f
in die entsprechenden trans,mer-[ReBr(CO)3L2]-Komplexe umge-
wandelt. Hierfür wird ein partieller Mechanismus vorgeschlagen.
den
entsprechenden
Phosphorliganden
und
trans,mer-
[ReBr(CO)3L2] erhalten. Alle Verbindungen
2 werden durch
1 Introduction
obtained by encouraging dissociation by the use of bulky
ligands such as P(OR)3 (R ϭ ortho-tolyl), the ligand in the
complex employed in Du Pont hydrocyanation,
[Ni{P(OR)3}4] [2]:
The design of 16-electron carbonyl complexes is often based
on the inclusion of easily abstracted groups such as methyl
or hydride in the coordination sphere of the metal the
highly electrophilic, electronically and coordinationally un-
saturated cation resulting from abstraction of these groups
being very effective in the activation of small molecules [1]:
[MX(L)5] Ǟ [MX(L)4] ϩ L
(2)
where X is a 1-electron donor ligand. In eqs. (1) and (2),
[ML5]ϩ and [MXL4] have the same formal electron de-
ficiency, but their interactions with nucleophiles are likely
to exhibit significant differences.
[MCH3(L)5] ϩ Ph3Cϩ Ǟ [M(L)5]ϩ ϩ Ph3CCH3
(1)
where M is a Group 7 metal and L is a 2-electron donor
ligand. However, interesting reactive fragments can also be
Steric effects also play important or dominant roles in
the substitution of [ReBr(CO)5] by PPh3-n(OR)n ligands [3]
and in the carbonylation of the resulting trisubstituted com-
plexes [ReBr(CO)2{PPh3-n(OR)n}3]. Envisaging that these
trisubstituted complexes may therefore prove useful as 16-
electron intermediate sources, we have synthesized and
spectroscopically characterized the six compounds cis,mer-
[ReBr(CO)2{PPh3-n(OR)n}3] [R ϭ Me (2a, 2c, 2e) or Et (2b,
2d, 2f); n ϭ 1 (2e, 2f), 2 (2c, 2d) or 3 (2a, 2b)]; this is the
first synthesis of 2e, and the first time that 2a and 2b have
´
´
* Dr. E. M. Vazquez-Lopez
´
´
Departamento de Qımica Inorganica
Facultade de Ciencias
Universidade de Vigo
E-36200 Vigo
Fax: ϩ34-986-812556
E-mail:ezequiel@uvigo.es
Z. Anorg. Allg. Chem. 2003, 629, 249Ϫ254  2003 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim 0044Ϫ2313/03/629/249Ϫ254 $ 20.00ϩ.50/0
249

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´
´
R. Carballo, P. Losada-Gonzalez, E. M. Vazquez-Lopez
Table 1 Selected IRa) and NMRb) data for the complexes.
been obtained as solids. We also studied compounds 2b-d
by X-ray diffractometry, and propose a partial mechanism
for the observed transformation of 2e and 2f into the corre-
sponding mer,trans-[ReBr(CO)3L2] complexes in chloro-
form or dichloromethane (in both of which 2a-d are stable).
ν(CO)
1H NMR
Assignment 31P NMR
CH3(LA,LB) 118.5m
J(31P-31P)
2a
2b
2c
2d
1975s
1873s
3.6m(27H)
1976s
1882s
4.06m(18H)
1.24m(27H)
CH2(LA,LB) 114.3m
CH3(LA,LB)
1996s
1886s
3.4d(16H)
3.6q(6H)
CH3(LA)
134.2d(LA)
2 Results and Discussion
CH3(LB)
135.3t(LB)
127.6d(LA)
130.0t(LB)
33
35
1980s
1870s
1.3m(12H)
3.7m(24H)
3.8m
CH3
CH2
2.1 Synthesis and spectral data
Attempts were made to synthesize all the compounds
cis,mer-[ReBr(CO)2L3] (2a-f: Lϭ PPh3-n(OR)n; R ϭ Me, Et;
n ϭ 1-3) by two different routes (Scheme 1): i) by reaction
of [ReBr(CO)5] with an excess of the appropriate phos-
phorus ligand, and ii) by reaction of the ligand with pre-
viously prepared mer,trans-[ReBr(CO)3L2] (1a-f).
4.0m
4.2m
2e
2f
1948s
1863s
2.9d(3H)
3.2t(6H)
CH3(LB)
CH3(LA)
CH3(LB)
CH3(LA)
CH2(LB)
101.0d(LA)
105.3t(LB)
35
32
1949s
1866s
0.99t(3H)
1.17t(6H)
3.12m(2H)
97.0d(LA)
103.6t(LB)
3,37m,3.47m(4H) CH2(LA)
b)
a)ν in cmϪ1, s ϭ strong. NMR spectra run in CDCl3, δ in ppm, J in Hz,
d ϭ doublet, m ϭ multiplet, q ϭ quartet, t ϭ triplet.
those of the corresponding phosphite and phosphonite
complexes is expected because of the greater donor capacity
of phosphinite ligands.
Scheme 1
The mer configuration of the three phosphorus ligands is
indicated in the 31P NMR spectra of 2c-f by the presence
of two sets of signals (Table 1): a doublet (LB) and, at
slightly lower field, a triplet (LA). The 31P-31P coupling con-
stants of these compounds are similar to those of the hy-
dride complexes [ReH(CO)2{PPh3-n(OEt)n}3] (n ϭ 1-3) [6],
even though the 31P signals of the bromide complexes all
lie about 15 ppm upfield from those of the hydrides.
The phosphite complexes (2a and 2b) were only isolated
as pure solids using path i, and the phosphinite complexes
(2e and 2f) by path ii, but the phosphonite complexes (2c
and 2d) were obtained by both routes. Note that 2a and 2b,
which were obtained by Reimann and Singleton [3] only as
oils, were in our study transformed into air-stable solids
when the oils were subjected to long periods under vacuum.
All of compounds 2 except 2e and 2f (vide infra) were ap-
parently stable for weeks in chloroform and in dichloro-
methane.
The mass spectra of compounds 2 all show a peak corre-
sponding to the molecular ion, albeit with differing intensit-
ies, but the base peak for all except 2c is the species resulting
from loss of one L and one CO. In keeping with the tend-
ency of 2e and 2f to lose a ligand in solution (vide infra),
the spectra of these two complexes each show a moderately
intense peak for ͉MϪL͉ that is missing or weak in those of
the other compounds.
The presence of two mutually cis carbonyl ligands is indi-
cated by the IR spectra of all of compounds 2 showing two
strong bands centred near 1970 and 1870 cm-1, close to
where they are observed in other [ReBr(CO)2L3] complexes
[4,5] (Table 1). The appearance of these bands at lower ener-
gies in the spectra of the phosphinite complexes than in
2.2 Structures of 2b, 2c and 2d
Figures 1Ϫ3 show PLATON [7] plots of asymmetric units
of 2b, 2c and 2d, together with the numbering schemes used.
Selected bond lengths and angles are listed in Table 2. The
crystals of all three compounds consist of isolated
[ReBr(CO)2L3] molecules with slightly distorted cis,mer oc-
tahedral configurations and no unusually short interatomic
distances. Compounds 2c and 2d are more distorted than
2b, but in all three the main distortions concern the angle
C2-Re-P3 and the P-Re-P angles.
In all three molecules, Re-C1 is shorter than Re-C2. This
suggests that there is considerable back-donation from the
metal atom to the C1 carbonyl group owing to the σ-donor
250
Z. Anorg. Allg. Chem. 2003, 629, 249Ϫ254

Rhenium(I) Dicarbonyl Complexes of Phosphite, Phosphonite, and Phosphinite
Fig. 1 Molecular structure of compound 2b, showing the number-
ing scheme (for clarity, just one position of the disordered groups
is shown).
Fig. 3 Molecular structure of compound 2d, showing the number-
ing scheme (for clarity, just one position of the disordered groups
is shown).
˚
Table 2 Main bond lengths/A and angles/° in compounds 2b, 2c
and 2d.
2b
2c
2d
ReϪC(1)
ReϪC(2)
ReϪP(1)
ReϪP(2)
ReϪP(3)
ReϪBr
1.851(9)/1.866(16)
1.945(9)
2.3742(19)
2.4188(19)
2.3897(19)
2.703(6)/2.734(8)
1.16(2)/1.19(4)
1.150(8)
1.917(6)
1.969(6)
2.3861(13)
2.4266(13)
2.3985(13)
2.6712(6)
1.098(6)
1.899(2)/1.899(2)
1.958(11)
2.384(3)
2.438(3)
2.382(3)
2.663(3)/2.669(4)
1.100(2)/1.100(2)
1.137(10)
C(1)ϪO(1)
C(2)ϪO(2)
1.135(7)
C(1)ϪReϪC(2)
C(1)ϪReϪP(1)
C(1)ϪReϪP(2)
C(1)ϪReϪP(3)
C(2)ϪReϪP(1)
C(2)ϪReϪP(2)
C(2)ϪReϪP(3)
C(1)ϪReϪBr
C(2)ϪReϪBr
BrϪReϪP(1)
BrϪReϪP(2)
BrϪReϪP(3)
P(1)ϪReϪP(2)
P(2)ϪReϪP(3)
P(1)ϪReϪP(3)
91.0(4)/88.3(8)
88.5(3)/93.4(9)
92.5(3)/88.2(8)
89.7(3)/88.3(9)
88.5(2)
176.5(2)
87.1(2)
178.8(3)/176.9(9)
88.0(2)/91.5(3)
91.93(7)/89.7(2)
88.53(7)/88.6(2)
89.74(7)/92.0(2)
91.84(7)
91.9(3)
88.1(8)/90.1(10)
92.6(6)/87.0(8)
88.2(7)/93.6(9)
91.3(6)/88.8(8)
87.0(3)
176.3(4)
85.6(3)
177.0(7)/179.3(9)
88.8(4)/89.4(4)
87.36(11)/92.47(13)
94.84(17)/86.94(13)
88.36(11)/91.58(13)
93.88(9)
86.55(15)
89.42(16)
87.08(15)
87.39(17)
178.53(19)
84.28(17)
178.25(16)
89.38(19)
92.36(4)
89.25(3)
94.20(4)
92.13(5)
96.35(4)
169.33(5)
Fig. 2 Molecular structure of compound 2c, showing the number-
ing scheme.
92.69(7)
175.21(7)
93.79(10)
171.50(10)
character of the trans bromine ligand, although there is sur-
prisingly no concomitant lengthening of C1-O1.
Another feature common to the three molecules is that
˚
the distance Re-P2 is 0.03-0.06 A longer than Re-P1 and
Re-P3. These latter are both close to the Re-P distances in
˚
Ph2P(CH2)2P(Ph)(CH2)2PPh2; 2.412(1)-2.420(3) A) [5]. The
lengthening of Re-P2 relative to Re-P1 and Re-P3 is usually
attributed to the influence of the trans carbonyl group, but
steric hindrance of the P2 position by the P1 and P3 ligands
probably also contributes [5].
the mer,trans complexes 1c and 1d [8], while Re-P2 is similar
˚
to the corresponding distances in 1e [2.415(2) A] [9], in
cis,mer-[ReBr(CO)2(L-L)L’] (L-L ϭ 1,2-bis(diphenylphos-
phonite)ethane, L’ ϭ P(OMe)3, P(OEt)3 or PPh(OEt)2;
˚
2.4390(9)-2.4631(11)A)
[4],
˚
in
fac-[ReBr(CO)3-
All three Re-P distances in 2b are shorter than their
counterparts in 2c and 2d, and Re-P2 is shorter in 2c than
in 2d. Both these differences are again likely to be due to
the greater steric demands of the more distant ligand.
{PPh2(OEt)}2] (2.4557(13) A) [8] and in phosphine deriva-
tives such as cis,mer-[Re(η1-pentadienyl)(CO)2(PMe3)3]
3
˚
(2.470(4) A) [10] and [ReCl(CO)2(L-L-L)] (L-L-L ϭ η -
Z. Anorg. Allg. Chem. 2003, 629, 249Ϫ254
251

´
´
´
R. Carballo, P. Losada-Gonzalez, E. M. Vazquez-Lopez
nism postulated by Darensbourg et al., by release of a mol-
ecule of the non-carbonyl ligand (Scheme 2, eq. (3)); this is
supported by the fact that, as in the reaction studied by
Darensbourg et al., the transformation of the substrate is
halted by addition of free ligand. The resulting 16-electron
product, [ReBr(CO)2L2], is expected to be highly reactive
and readily carbonylated to 1e or 1f (Scheme 2, eq. (4)), but
the source of the carbonyl required for this step remains
uncertain. It seems unlikely to be an unaltered substrate
molecule, because this ought to lead to the formation of
[ReBr(CO)L4] in amounts similar to the yields of 1e or 1f,
and this is not observed in the 31P NMR spectra of the
reaction mixture (instead, the ligand released in the first
step, eq. (3), is oxidized to the corresponding phosphinic
acid ester; Scheme 2, eq. (5)). Our research plans in this
area accordingly include not only investigation of possible
applications of this reaction, but also experiments to ident-
ify the CO source that it involves.
Fig. 4 31P NMR spectra of a solution of 2e in CDCl3 when freshly
prepared (a) and after 24 h (b), 48 h (c) and 144 h (d). Origin of
signals: ϩ, 2e; ꢀ, 1e; X, OϭPPh2(OMe); ∨, unknown.
2.3 Behaviour in chloroform and dichloromethane
At room temperature, 2a-d can be stored for weeks in
chloroform or dichloromethane without apparent de-
composition, but 2e and 2f slowly decompose under these
conditions. After 24 h in CDCl3 the 31P NMR signals of
2e have weakened and signals at 101.8 and 32.9 ppm due
respectively to 1e [8] and phosphinic acid methyl ester [11]
have appeared; and after 1 week the signals of 2e have com-
pletely vanished (Fig. 4), leaving solutions that yield a solid
with an IR spectrum confirming the presence of 1e and
P(O)Ph2(OMe). Compound 2f behaves similarly.
3 Experimental
3.1 Materials and instrumentation
All operations were carried out under an atmosphere of dry argon.
All solvents were dried over appropriate drying agents, degassed
on a vacuum line and distilled in an Ar atmosphere [15].
[ReBr(CO)5] was synthesized by the published method [16]. Phos-
phorus ligands were used as supplied by Aldrich without any
further purification. Complexes 1 (mer,trans-[ReBr(CO)3L2]) were
obtained as previously described [8]. Elemental analyses were car-
ried out on a Fisons EA-1108. Melting points (m.p.) were deter-
mined on a Gallenkamp MFB-595 and are uncorrected. Mass spec-
tra were recorded on a Micromass spectrometer operating under
FAB conditions (nitrobenzyl alcohol matrix). Infrared spectra were
recorded on a Bruker Vector 22FT spectrophotometer. NMR spec-
tra were obtained on a Bruker AMX 400 spectrometer; 1H chemical
shifts are referred to internal tetramethylsilane (TMS) and 31P{1H}
chemical shifts to H3PO4.
Similar reactions have been reported previously. Carriedo
and Riera [12] observed the formation of [Mn(diphos)-
(CO)4][ClO4] (diphos ϭ dpm, dpe, dpp or dbp) when solu-
tions containing fac-[MnBr(CO)3(diphos)] and AgClO4
were stirred; in this case the presence of Agϩ seems neces-
sary because pure fac-[MnBr(CO)3(diphos)] does not de-
compose. Also, Darensbourg et al. [13, 14] have reported
that certain pentacarbonyl amine complexes of Group 6
metals decompose to the corresponding hexacarbonyl com-
pounds in both hexane and carbon disulphide; in this case
the authors put forward a dissociative mechanism in which
the rate-limiting step is the cleavage of the metal-nitrogen
bond, which is followed by the released amine’s displacing
CO from a second molecule of the pentacarbonyl amine
complex and by coordination of this CO to the de-aminated
molecule. Weighing against this mechanistic hypothesis is
the fact that the complex [M(CO)4(amine)2] was neither iso-
lated nor characterized, but assuming that pKa is correlated
with the coordinating strength of the ligand it does explain
why the rate constant of these reactions decreases as the
basicity of the amine rises.
3.2 Synthesis of cis,mer-[ReBr(CO)2L3]
[L ϭ phosphite (P(OR)3; 2a and 2b) or phosphonite
(PPh(OR)2; 2c and 2d)] from [ReBr(CO)5].
An excess of the appropriate phosphorus ligand (2a 0.17 mL, 1.44
mmol; 2b 0.34 mL, 1.97 mmol; 2c 0.47 mL, 2.95 mmol; 2d 0.57
mL, 2.95 mmol) was added to a suspension of [ReBr(CO)5] (2a,b
200 mg, 0.49 mmol; 2c,d 300 mg, 0.74 mmol) in toluene (30 mL)
and the mixture was refluxed for 4 h and gently stirred for another
18 h at room temperature. The solvent was then removed under
vacuum and the resulting oil was stirred with MeOH or EtOH (4
mL). The white precipitate thereupon formed was filtered off,
washed with MeOH or EtOH and vacuum dried. Yields: 2a, 160
mg (47%); 2b, 185 mg (46%); 2c, 431 mg (70%); 2d, 543 mg (80%).
cis,mer-[ReBr(CO)2(L)3] Ǟ [ReBr(CO)2(L)2] ϩ L
[ReBr(CO)2(L)2] [COǞ] mer,trans-[ReBr(CO) (L) ]
(3)
(4)
(5)
ᎏᎏ
3
2
[O ]
L
2Ǟ OϭL
ᎏᎏ
Analytical and spectral data. Data for 2a. M.p.: 198°C. Anal.
found: C, 19.6; H, 4.2%. C11H27O11P3BrRe requires: C, 19.0; H,
3.9%.
Scheme 2
We hypothesize that the spontaneous transformation of 2e
and 2f into 1e and 1f starts in the same way as the mecha-
Mass spectrum (FAB): ͉M͉ 693(15), ͉MϪCO͉ 666(70), ͉MϪ(CO,OR)͉
635(18), ͉MϪBr͉ 615(21), ͉MϪ(CO,L)͉ 542(100), ͉MϪ(CO,OR,L)͉ 511(54).
252
Z. Anorg. Allg. Chem. 2003, 629, 249Ϫ254

Rhenium(I) Dicarbonyl Complexes of Phosphite, Phosphonite, and Phosphinite
Data for 2b. M.p.: 57°C. Anal. found: C, 29.7; H, 5.8%.
Table 3 Crystal and structure refinement data.
C20H45O11P3BrRe requires: C, 29.3; H, 5.5%.
2b
2c
2d
Mass spectrum (FAB): ͉M͉ 820(62), ͉MϪCO͉ 792(75), ͉MϪ(CO,OR)͉
747(44), ͉MϪBr͉ 741(52), ͉MϪL͉ 654(7), ͉MϪ(CO,L)͉ 626(100),
͉MϪ(CO,OR,L)͉ 581(71).
Chemical formula
Formula weight
Crystal system
Space group
C20H45O11P3BrRe C26H33O8P3BrRe C32H45O8P3BrRe
820.58
832.54
916.70
monoclinic
P21/n (No. 14)
11.6710(19)
16.2028(13)
18.2417(14)
99.318(2)
3404.0(5)
4
1601
293
4929
17694
monoclinic
C2/c (No. 15)
35.500(7)
9.8693(12)
20.826(4)
120.110(14)
6306(2)
8
1741
293
5316
6494
orthorhombic
Pbca (No. 61)
17.626(2)
18.649(2)
23.253(2)
Ϫ
7643.3(12)
8
1593
293
4395
6450
6450(0)
Data for 2c. M.p.: 125°C (lit. 123°C [3]). Anal. found: C, 38.1; H,
4.0%. C26H33O8P3BrRe requires: C, 37.5; H, 4.0%.
˚
a/A
˚
Mass spectrum (FAB): ͉M͉ 832(46), ͉MϪCO͉ 804(100), ͉MϪ(CO,OR)͉
773(39), ͉MϪBr͉ 753(52), ͉MϪ(CO,Br)͉ 725(15), ͉MϪ(CO,L)͉ 634(96),
͉MϪ(CO,OR,L)͉ 603(96).
b/A
˚
c/A
β/°
3
˚
V/A
Data for 2d. M.p.: 133°C (lit. 129°C [3]). Anal. found: C, 42.3; H,
4.9%. C32H45O8P3BrRe requires: C, 41.4; H, 5.0%.
Z
DX/Mg mϪ3
Temperature/K
µ/mmϪ1
Mass spectrum (FAB): ͉M͉ 916(46), ͉MϪCO͉ 888(90), ͉MϪ(CO,OR)͉
843(45), ͉MϪBr͉ 837(39), ͉MϪL͉ 718(7), ͉MϪ(CO,L)͉ 690(100),
͉MϪ(CO,OR,L)͉ 843(45).
Reflections measured
Independent reflections 7373(0.0743)
(Rint
R1/wR2 (I>2σ(I))
6387(0.0379)
)
0.0377/0.0662
0.0364/0.0720
0.0470/0.0662
3.3 Synthesis of the phosphonite complexes 2c and 2d
from mer,trans-[ReBr(CO)3L2]
To a suspension of mer,trans-[ReBr(CO)3L2] (2c 100 mg, 0.14
mmol; 2d 100 mg, 0.13 mmol) in toluene (20 mL) was added an
excess of the phosphorus ligand (2c 0.1 mL, 0.63 mmol; 2d 0.1 mL,
0.54 mmol) and the mixture was refluxed for 4 h. The solvent was
then removed under vacuum and the resulting oil was stirred with
MeOH or EtOH (4 mL). The white precipitate formed was filtered
off, washed with MeOH or EtOH and vacuum dried. Yields: 2c,
28 mg (24%); 2d, 68 mg (57%).
fects. Ψ-scan or multi-scan (SADABS) absorption corrections were
also applied [17].
The structures of the compounds were analysed out by the heavy
atom method [18] followed by Fourier techniques until all non-
hydrogen atoms were located. The mutually trans bromide and car-
bonyl groups of 2b and 2d are orientationally disordered but this
was modelled successfully using occupancy factors of 75 and 25%
for 2b and 54 and 46% for 2d in the two alternative sites. The
positions of H atoms were calculated geometrically and refined
with the atoms as riders.
3.4 Synthesis of the phosphinite complexes cis,mer-
[ReBr(CO)2L3] [L ϭ PPh2(OR); 2e and 2f].
Scattering factors and anomalous dispersion terms were taken from
Ref. [18]. Most calculations were performed with the programs
SHELX97 [19] and PLATON [7].
To a suspension of 1 (200 mg; 1e 0.26 mmol, 1f 0.25 mmol) in
toluene (20 mL) was added an excess of the corresponding phos-
phinite ligand (2e 0.2 mL, 0.99 mmol; 2f 0.4 mL, 1.85 mmol) and
refluxing of the mixture was begun. Without halting refluxing,
further amounts of ligand (2e 0.15 mL, 0.75 mmol; 2f 0.3 mL, 1.35
mmol) were added 7 and 14 h later. Nine hours after the last ad-
dition (23 h fater the start of refluxing), the solvent was removed
under vacuum and the resulting oil was stirred with MeOH (2e) or
EtOH (2f). The white solid formed thereby was filtered off, washed
with MeOH or EtOH, and vacuum dried.
Crystallographic data for the structures reported in this paper (ex-
cluding structure factors) have been deposited with the Cambridge
Crystallographic Data Centre as Supplementary Publications
CCDC-194218 (2b), CCDC-194219 (2c) and CCDC-194220 (2d).
Copies of the data can be obtained free of charge on application
to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK [Fax: int.
Code ϩ44(1223)336-033; E-mail: deposit@ccdc.cam.ac.uk].
Data for 2e. M.p.: 155Ϫ8°C (dec.). Yield: 189 mg (75%). Anal.
found: C, 50.8; H, 4.7%. C41H39O5P3BrRe requires: C, 50.7; H,
4.5%.
Acknowledgement. We thank the DGESIC (Spain) and DGRP
(E.U., ERDF programs) for financial support (Ref. BQU2002-
03543).
Mass spectrum (FAB): ͉M͉ 970(51), ͉MϪCO͉ 942(15), ͉MϪ(CO,OR)͉
911(19), ͉MϪBr͉ 891(29), ͉MϪL͉ 754(36), ͉MϪ(L,CO)͉ 726(100),
͉MϪ(L,CO,OR)͉ 695(25).
References
Data for 2f. M.p.: 150°C (dec., lit. 142Ϫ5°C [3]). Yield: 190 mg
(75%). Anal. found: C, 50.6; H, 5.0%. C44H45O5P3BrRe requires:
C, 52.2; H, 4.5%.
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