Tertiary phosphine binding to pyridylazole chelated rhenium via substitution in phosphine oxide precursors: Geometrical preference, twin isomerization and effects of diphosphine spacer length and metal oxidation state

Article abstract of DOI:10.1039/b307834e

The bimolecular reaction of [Re^VL(O)Cl₃][L = 2-(2-pyridyl)benzoxazole (L¹), 2-(2-pyridyl)benzthiazole (L²)], 1 with excess diphosphine [Ph₂P(CH₂)_xPPh₂ (x = 1-4)] has furnished [Re^IIIL(OP(Ph)₂(CH₂)_x P(Ph)₂)Cl₃], 2 which is spontaneously converted in solution to [Re^IIIL(P(Ph)₂(CH₂)_xP(O) (Ph)₂)Cl₃], 4. The reaction of [Re^IIIL(OPMe_yPh_3-y)Cl₃], 3 with PMe_yPh_3-y (y = 0-2) has afforded [Re^IIIL(PMe_yPh_3-y)Cl₃], 5. Oxidation of 2 and 3 by dilute nitric acid has furnished nitrates of the rhenium(IV) species, 2⁺ and 3⁺. Structure determination vis-a-vis spectral and electrochemical comparisons have revealed a meridional geometry for 2, 3, 2⁺, and 3⁺ and a facial geometry for 4 and 5. The transformation 2 → 4 is a twin isomerization (linkage-cum-geometrical), the geometrical part of which recurs in the conversion 3 → 5. Rate studies have revealed that the reaction 2 → 4 is intramolecular in nature. It is initiated by nucleophilic attack of the metal by the dangling phosphine function. The process slows down nearly exponentially as the diphosphine spacer length (x) increases. The oxidised complex 2⁺ does not isomerize.

Full text of DOI:10.1039/b307834e

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Tertiary phosphine binding to pyridylazole chelated rhenium via
substitution in phosphine oxide precursors: geometrical preference,
twin isomerization and effects of diphosphine spacer length and
metal oxidation state
Suman Sengupta,a Jaydip Gangopadhyaya and Animesh Chakravorty*a,b
a Department of Inorganic Chemistry, Indian Association for the Cultivation of Science,
Kolkata, 700 032, India. E-mail: icac@mahendra.iacs.res.in
b Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, 560 064, India
Received 9th July 2003, Accepted 19th September 2003
First published as an Advance Article on the web 13th October 2003
The bimolecular reaction of [ReVL(O)Cl3] [L = 2-(2-pyridyl)benzoxazole (L1), 2-(2-pyridyl)benzthiazole (L2)],
1 with excess diphosphine [Ph2P(CH2)xPPh2 (x = 1–4)] has furnished [ReIIIL(OP(Ph)2(CH2)xP(Ph)2)Cl3], 2
which is spontaneously converted in solution to [ReIIIL(P(Ph)2(CH2)xP(O)(Ph)2)Cl3], 4. The reaction of
[ReIIIL(OPMeyPh3 Ϫ y)Cl3], 3 with PMeyPh3 Ϫ y (y = 0–2) has afforded [ReIIIL(PMeyPh3 Ϫ y)Cl3], 5. Oxidation of 2 and
3 by dilute nitric acid has furnished nitrates of the rhenium() species, 2ϩ and 3ϩ. Structure determination vis-à-vis
spectral and electrochemical comparisons have revealed a meridional geometry for 2, 3, 2ϩ, and 3ϩ and a facial
geometry for 4 and 5. The transformation 2
part of which recurs in the conversion 3
4 is a twin isomerization (linkage-cum-geometrical), the geometrical
5. Rate studies have revealed that the reaction 2 4 is intramolecular in
nature. It is initiated by nucleophilic attack of the metal by the dangling phosphine function. The process slows down
nearly exponentially as the diphosphine spacer length (x) increases. The oxidised complex 2ϩ does not isomerize.
phosphorus species of type ReIII(OPR3), ReIV(OPR3) and ReIII-
Introduction
(PR3) have also been examined. The complexes have been
This work has originated from our interest in oxygen atom
characterised with the help of spectral, electrochemical and
transfer reactions between monooxorhenium() reagents and
crystallographic data. The factors controlling structure and
reactivity are scrutinised.
tertiary phosphines.1–7 The available results primarily concern
monophosphines. Diphosphines are potentially interesting but
have attracted only limited attention so far.8–10 Recently we
reported a pair of oxo chelates of type [ReVL(O)Cl3], 1, where L
is 2-(2-pyridyl)benzoxazole (L1) or 2-(2-pyridyl)benzthiazole
(L2).
Results and discussion
Compound types and their synthesis
Four diphosphines and three monophosphines have been
employed in the present work: Ph2P(CH2)xPPh2 (x = 1–4) and
PMeyPh3 Ϫ y (y = 0–2). All the complexes reported below have
been isolated in excellent yields. In order to achieve transfer of
only one oxygen atom to the diphosphines, excess of the latter
was reacted (eqn. (2))
1 ϩ Ph2P(CH2)xPPh2
2
(2)
with 1 in dichloromethane solution furnishing the species of
type 2 where D is coordinated at oxygen. The monophosphorus
complexes of type 3 except y = 2 are known.11
These underwent facile bimolecular oxygen atom transfer
reactions with the monophosphines (PR3, R = Me/Ph) furnish-
ing the corresponding phosphine oxide complexes as shown
schematically in eqn. (1).11
V
ReIII–OPR3
(1)
᎐
Re ᎐O ϩ PR
᎐
3
The present work was initiated to scrutinise the transfer
reactions of 1 with a group of linear diphosphines bearing a
polymethylene spacer of variable length. Attention has been
focussed on the transfer of one oxygen atom only so that phos-
phine oxide complexes with a dangling phosphine function are
generated. The latter function could be a potential nucleophile
that might attack the metal site within the same molecule. Such
reactivity has indeed been observed providing an opportunity
to scrutinise the effects of diphosphine spacer length and metal
oxidation state. To model the observed phenomenon mono-
The rate of the reaction of eqn. (2) has been determined
spectrophotometrically in dichloromethane solution at 308 K
for the x = 4 case where the subsequent isomerization (vide
infra) proceeds very slowly. In the presence of excess diphos-
phine the rate of transfer is proportional to the concentration
T h i s j o u r n a l i s © T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 3
D a l t o n T r a n s . , 2 0 0 3 , 4 6 3 5 – 4 6 4 3
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Table 1 Rate constants for the reaction of [ReL(O)Cl3] with [Ph2P-
Table 2 Selected bond distances (Å) and angles (Њ) for compound 3a
(CH2)4PPh2] in dichloromethane solution at 308 Ka
Re–N1
Re–N2
Re–O
2.054(6)
2.063(6)
2.078(5)
2.402(2)
Re–Cl2
Re–Cl3
P–O
2.361(3)
2.367(2)
1.520(6)
L
102[Ph2P(CH2)4PPh2]/M
102kobs/minϪ1
k/MϪ1 minϪ1
L1
1.06
1.40
2.00
1.06
1.40
2.00
1.65(0.01)
2.29(0.01)
3.38(0.01)
0.77(0.01)
1.07(0.01)
1.57(0.01)
1.84(0.01)
Re–Cl1
N1–Re–N2
N2–Re–O
77.5(3)
95.3(2)
90.0(2)
91.4(2)
89.4(2)
96.2(2)
91.0(2)
90.49(8)
N1–Re–O
N1–Re–Cl2
O–Re–Cl2
N2–Re–Cl3
Cl2–Re–Cl3
N2–Re–Cl1
Cl2–Re–Cl1
P–O–Re
172.7(3)
89.8(2)
89.5(2)
L2
0.85(0.01)
N2–Re–Cl2
N1–Re–Cl3
O–Re–Cl3
N1–Re–Cl1
O–Re–Cl1
Cl3–Re–Cl1
90.8(2)
178.71(8)
173.6(2)
88.81(8)
140.1(4)
a The initial concentration of [ReL(O)Cl3] is 1.25 × 10Ϫ4 M. Least-
squares deviations are given in parentheses.
of 1 and the observed rate constant is proportional to the con-
centration of phosphine implying a second order rate law. The
k values (Table 1) which lie close to those for the reaction
of [ReL(O)Cl3] with PMePh2 follow the order [ReL1(O)Cl3] >
[ReL2(O)Cl3] as expected.11
The complexes of type 2 are inherently reactive in dichloro-
methane solution, the dangling phosphine function displacing
the coordinated phosphine oxide function furnishing 4 where
DЈ is coordinated at phosphorus. This linkage isomerization is
ligands resonate in the range 4 to 9 ppm (2, 3), 5 to 20 ppm
(4, 5) and 5 to 10 ppm (2ϩ, 3ϩ). Lastly, the CH2/Me resonances
fall in the ranges Ϫ11 to Ϫ1 ppm (2, 3), Ϫ4 to 8 ppm (4, 5) and
4 to 7 ppm (2ϩ, 3ϩ).
The complexes uniformly display a nearly reversible ReIV/
ReIII couple, in acetonitrile solution, the cyclic voltammetric
peak-to-peak separation being 60–80 mV. The reduction poten-
tials lie near 0.24 V vs. SCE in 2 and 311 and near 0.58 V in 4
and 5. The sizeable difference of reduction potentials makes it
possible to observe the isomerization of 2 to 4 electrochemically
as shown in Fig. 1. Quantitative isomerization studies are how-
ever best made spectrophotometrically, vide infra. The voltam-
mograms of 2ϩ and 3ϩ (initial scan cathodic) are virtually
superimposable on those of the corresponding 2 and 3 species
(initial scan anodic). The t2g shell in 4 and 5 is stabilised by
back-bonding to phosphorus (vide infra) and an increase of the
reduction potential is indeed expected in going from phosphine
oxide to phosphine coordination.
simultaneously attended by meridional
facial geometrical
isomerization. The nature and rate of this twin isomerization
process will be examined later. The geometrical part in the 2
4 transformation has been realised in monophosphorus species.
Thus upon treating the meridional phosphine oxide complexes
of type 3 with excess PMeyPh3 Ϫ y in boiling benzene facial
phosphine complexes of type 5 are formed, eqn. (3).
3 ϩ PMeyPh3 Ϫ y
5 ϩ OPMeyPh3 Ϫ y
(3)
The phosphine oxide complexes 2 and 3 underwent facile
metal oxidation upon treatment with dilute nitric acid in
acetonitrile solution furnishing the corresponding rhenium()
cations 2ϩ and 3ϩ which were isolated as nitrates in the repre-
sentative cases of [ReIVL(OP(Ph)2CH2P(Ph)2)Cl3]ϩ and [ReIV-
L(OPPh3)Cl3]ϩ. The nitrates act as 1 : 1 electrolytes in methanol
solution (Λ, 92–99 ΩϪ1 cm2 molϪ1). Attempted oxidation of the
phosphine complexes 4 and 5 by dilute nitric acid furnished
highly insoluble compounds which could not be characterised.
Spectra and electrochemistry
In the visible region (400–900 nm) 2–5 display multiple transi-
tions of moderate intensity (ε, 1000–5000 dm3 molϪ1 cmϪ1) in
the form of peaks and shoulders. The most prominent feature
occurs around 740 nm in 2 and 3 and around 700 nm in 4 and 5.
An idealised t2g(Re)
π*(L) MLCT assignment is consistent
with the observed shift to higher energy in going from phos-
phine oxide (2, 3) to phosphine coordination (4, 5) which
stabilises the t2g shell via back-bonding. This is also reflected in
the significant increase of the ReIV/ReIII reduction potentials
(vide infra). The rhenium() species 2ϩ and 3ϩ in which MLCT
transitions are expected to shift to much higher energies, do
not display any band in the visible region except for a weak
shoulder around 430 nm.
Fig. 1 Cyclic voltammetric observation of the isomerization of
[ReL2(OP(Ph)2CH2P(Ph)2)Cl3] in acetonitrile solution in the time
domain 0–24 h : (a) 0 h, (b) 2 h, (c) 6 h, (d) 24 h.
Structures
Two or three Re–Cl stretches occur in all the complexes
(300–350 cmϪ1) along with a C᎐N stretch near 1600 cmϪ1. The
The structures of [ReL2(OPMe2Ph)Cl3], 3a; [ReL2(OPPh3)-
᎐
coordinated P–O stretch (2, 3) is observed near 1130 cmϪ1 as
compared to ≈ 1180 cmϪ1 characterising uncoordinated P–O
(4). In 2ϩ and 3ϩ the oxidised metal weakens the P–O bond and
the vibration frequency drops to ≈ 1115 cmϪ1. The ν3 vibra-
tion12 of NO3Ϫ is seen at 1384 cmϪ1 in the nitrates of 2ϩ and 3ϩ.
All the complexes display paramagnetically shifted2,3,8,11,13,14
1H NMR spectra which have characteristic chemical shifts for
each type of compound. Well-resolved spin–spin structures are
seen for 2–5 but not for 2ϩ and 3ϩ. The L proton resonances
occur in the ranges 5 to 30 ppm (2, 3), Ϫ12 to 25 ppm (4, 5) and
4 to 57 ppm (2ϩ, 3ϩ). The aromatic protons of the phosphorus
Cl3]NO3ؒ0.5CH2Cl2, 3bϩNO3 ؒ0.5CH2Cl2; [ReL1(PMe2Ph)Cl3],
Ϫ
5a and [ReL1(PMePh2)Cl3]ؒH2O, 5bؒH2O have been deter-
mined. Perspective views are shown in Fig. 2–5 and selected
bond parameters are listed in Tables 2, 3 and 4.
The type 3 complexes reported earlier did not afford single
crystals suitable for determination of a satisfactorily refined
structure.11 This has now been achieved with the new complex
3a. The severely distorted octahedral geometry has a merid-
ional disposition of chloride ligands (Fig. 2). The pyridine ring
makes a dihedral angle of 16.9Њ with the benzthiazole moiety
and consequently the ReL2 fragment is not quite planar (mean
D a l t o n T r a n s . , 2 0 0 3 , 4 6 3 5 – 4 6 4 3
4636

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Table 3 Selected bond distances (Å) and angles (Њ) for compound
3bϩNO3 ؒ0.5CH2Cl2
Ϫ
Molecule 1
Molecule 2
Re–N1
Re–N2
Re–O1
Re1–Cl1
Re1–Cl2
Re1–Cl3
P1–O1
2.115(8)
Re51–N51
Re51–N52
Re51–O51
Re51–Cl51
Re51–Cl52
Re51–Cl53
P51–O51
2.122(8)
2.134(8)
2.002(6)
2.292(3)
2.323(3)
2.317(3)
1.529(7)
2.113(8)
2.034(6)
2.298(3)
2.336(3)
2.304(3)
1.532(7)
N1–Re1–N2
N2–Re1–O1
N2–Re1–Cl2
N1–Re1–Cl3
O1–Re1–Cl3
N1–Re1–C11
O1–Re1–C11
Cl3–Re1–Cl1
N1–Re1–O1
N1–Re1–Cl2
O1–Re1–Cl2
N2–Re1–Cl3
Cl2–Re1–Cl3
N2–Re1–C11
Cl2–Re1–C11
P1–O1–Re1
76.7(4)
99.0(3)
84.7(2)
87.9(2)
90.6(2)
93.7(3)
90.6(2)
94.39(13)
175.5(3)
89.6(2)
91.3(2)
88.7(2)
173.38(11)
169.8(3)
91.90(13)
140.4(4)
N51–Re51–N52
N52–Re51–O51
N52–Re51–Cl52
N51–Re51–Cl53
O51–Re51–Cl53
N51–Re51–Cl51
O51–Re51–Cl51
Cl53–Re51–Cl51
N51–Re51–O51
N51–Re51–Cl52
O51–Re51–Cl52
N52–Re51–Cl53
Cl52–Re51–Cl53
N52–Re51–Cl51
Cl52–Re51–Cl51
P51–O51–Re51
77.5(3)
97.4(3)
85.4(2)
88.0(2)
89.8(2)
92.8(3)
92.5(2)
93.59(12)
174.4(3)
91.2(2)
90.5(2)
88.9(2)
174.28(10)
169.8(2)
92.10(12)
159.4(5)
Fig. 2 A perspective view of [ReL2(OPMe2Ph)Cl3] 3a. The atoms are
represented by their 30% thermal probability ellipsoids.
Fig. 4 A perspective view of [ReL1(PMe2Ph)Cl3] 5a. The atoms are
represented by their 30% thermal probability ellipsoids.
Fig. 3 A perspective view of molecule 1 of [ReL2(OPPh3)Cl3]ϩ 3bϩ.
The atoms are represented by their 30% thermal probability ellipsoids.
deviation 0.18 Å). The P atom lies 2.65 and 2.73 Å away from
the centroids of the octahedral faces defined by O, Cl(1), Cl(3)
and O, Cl(1), Cl(2) respectively. The corresponding distances
from the centroids of the O, N(2), Cl(2) and O, N(2), Cl(3) faces
are > 3.1Å. The nucleophilic attack of PMe2Ph on [ReL2(O)Cl3]
had logically occurred near the less hindered faces defined by
the chloride and oxo ligands.
Ϫ
The asymmetric unit of 3bϩNO3 ؒ0.5CH2Cl2 consists of two
structurally very similar but crystallographically distinct 3bϩ
cations (along with two nitrate ions and one dichloromethane
molecule), only one of the cations being shown in Fig. 3. The
geometry of the 3bϩ cation is grossly similar to that of 3a but
the ReL2 fragment is more planar (average mean deviation
0.05 Å) in this case. The metal–ligand bond lengths of 3bϩ are
significantly different from those of 3a. The average Re–Cl
Fig. 5 A perspective view of [ReL1(PMePh2)Cl3] 5b. The atoms are
represented by their 30% thermal probability ellipsoids.
and Re–O distances in 3bϩ are respectively ≈ 0.07 and ≈ 0.06 Å
shorter than those in 3a. These bonds are primarily σ in char-
acter and the contraction of metal radius upon oxidation is
D a l t o n T r a n s . , 2 0 0 3 , 4 6 3 5 – 4 6 4 3
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Table 4 Selected bond distances (Å) and angles (Њ) for compounds 5a
and 5bؒH2O
Table 5 Rate constants for the isomerization of [ReL(OP(Ph)2(CH2)x-
P(Ph)2)Cl3] in dichloromethane solution at 308 Ka
5a
5bؒH2O
L
x
104[ReL(OP(Ph)2(CH2)xP(Ph)2)Cl3]/M
103k/minϪ1
Re–N1
Re–N2
Re–Cl1
Re–Cl2
Re–Cl3
Re–P
2.089(8)
2.060(8)
2.408(3)
2.338(3)
2.349(3)
2.373(3)
2.110(5)
2.098(5)
2.438(2)
2.354(2)
2.358(2)
2.414(2)
L1
1
1.25
2.50
3.75
1.25
1.25
1.25
1.25
2.50
3.75
1.25
1.25
1.25
5.05(0.03)
5.07(0.02)
5.06(0.03)
2.44(0.01)
0.95(0.01)
0.40(0.01)
2.17(0.01)
2.16(0.01)
2.17(0.01)
1.08(0.01)
0.43(0.01)
0.15(0.01)
2
3
4
1
L2
N2–Re–N1
N1–Re–Cl2
N1–Re–Cl3
N2–Re–P
76.4(3)
93.6(2)
171.3(2)
96.5(2)
89.17(11)
84.1(2)
90.39(11)
178.73(9)
168.6(2)
95.2(2)
94.97(11)
91.7(2)
86.86(10)
89.5(2)
75.7(2)
93.66(13)
170.76(13)
91.23(14)
88.25(6)
88.69(14)
91.13(6)
176.18(5)
169.40(13)
95.02(13)
95.58(6)
88.89(13)
91.73(6)
2
3
4
Cl2–Re–P
N2–Re–Cl1
Cl2–Re–Cl1
P–Re–Cl1
N2–Re–Cl2
N2–Re–Cl3
Cl2–Re–Cl3
N1–Re–P
Cl3–Re–P
N1–Re–Cl1
Cl3–Re–Cl1
a Least-squares deviations are given in the parentheses.
Twin isomerization
The spontaneous isomerization of 2 to 4 (eqn. (4)),
87.38(13)
92.09(6)
2
4
(4)
91.99(10)
has been examined spectrophotometrically at 308 K in di-
chloromethane solution. Time evolution spectra are character-
ised by multiple isosbestic points in the visible region (Fig. 6).
The rate of the reaction is independent of the concentration of
2 consistent with its intramolecular nature. The rate constants
for the family of type 2 species are collected in Table 5.
registered in their lengths. In striking contrast, the average Re–
N distance in 3bϩ is ≈ 0.07 Å longer than that in 3a. Trivalent
rhenium is a potent π-donor3,8,16 but metal oxidation is
expected to diminish the donor power very considerably. The
longer Re–N bond in 3bϩ is believed to reflect the weakness or
absence of back-bonding in the ReIVL2 fragment.
In both 5a and 5b the ReCl3 fragment is facially disposed
(Fig. 4 and 5), the L1 ligand is approximately planar and so is
the ReL1 fragment. The average Re–Cl distances are virtually
the same as that in 3a (2.37–2.38 Å). On the other hand, the
average Re–N length of 5a and 5b is ≈ 0.03 Å longer. This is
consistent with the presence of Re–P back-bonding which
diminishes the demand on π*(L) orbitals as compared to that
in 3a where only Re–L2 back-bonding is possible (phosphine
oxide is a pure σ-donor). In the lattice of 5bؒH2O there are
actually two types of water molecule: one lying in a general
position but displaying a two-fold disorder with respect to a
crystallographic C2 axis and the other sitting on a special pos-
ition (two-fold axis). The two water molecules of adjacent
symmetry related complexes are strongly hydrogen bonded
(2.531(7) Å).
When phosphine and L are coligands, the net back-
bonding is stronger in the facial (as opposed to meridional)
arrangement in which the competition between the two ligands
for identical metal orbitals is minimal. Thus 5 has facial
geometry while 3 (here only L is π acidic) assumes the steric-
ally and electrostatically superior meridional configuration.
The strong geometrical differences between Re(PR3)Cl3 and
Re(OPR3)Cl3 chelates of π-acidic N,N donor ligands appear
to be a general phenomenon which has previously been docu-
mented by us in the cases of pyridylaldimine13 and azo2,8,9
ligands.
Fig. 6 Time evolution spectra for the twin isomerization reaction of
[ReL1(OP(Ph)2CH2P(Ph)2)Cl3] in dichloromethane solution at 308 K
(At is absorbance).
Phosphine bulk inequality (cone angle, PMe2Ph < PMePh2)
has a subtle effect on metal–ligand bond lengths (5a < 5b). The
difference in the case of the Re–P bond is ≈0.04 Å. The type
5 compounds with the bulkier PPh3 did not afford suitable
crystals but the average Re–P distances in related facial com-
plexes8,13 bearing PPh3 coordination is ≈0.07 Å longer than that
in 5b.
It is logical to assume that the transformation is initiated via
nucleophilic attack of the metal by the dangling phosphine
function. The isomerization rates of the L1 complexes are
systematically higher (nearly twice) than those of the corre-
sponding L2 species. This is consistent with heteroatom electro-
negativity (O > S) which makes the metal more susceptible to
attack in the L1 complexes. The attack is stylised in Scheme 1
where a less crowded OCl2 face near which the phosphine oxide
ligand is likely to be positioned (see structure of 3a) is shown to
be the site of initial action. The transformation can then
The diphosphorus compounds of types 2, 4 and 2ϩ did not
afford suitable single crystals for structure determination. How-
ever, on the basis of spectral and electrochemical analogy with
the monophosphorus species it is clear that these have the same
gross structures as 3, 5 and 3ϩ respectively.
D a l t o n T r a n s . , 2 0 0 3 , 4 6 3 5 – 4 6 4 3
4638

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Conclusion
It is demonstrated that the family 2 formed from [ReL(O)Cl3]
and Ph2P(CH2)xPPh2 (x = 1–4) undergoes spontaneous intra-
molecular linkage-cum-geometrical isomerization in solution
affording 4. The same geometrical isomerization recurs in the
conversion of 3 to 5.
Significant ReIIIL (2–5) and ReIIIP (4, 5) back-bonding char-
acterises the species and this logically plays a crucial role in
directing the course of isomerization and in determining the
trend (4(5) > 2(3)) of MLCT excitation energy and ReIV/ReIII
reduction potential.
Scheme 1
progress rationally via edge displacement8,17 of a chloride ligand
resulting in the relay substitutions: Re–OP by Re–Cl and of
Re–Cl by Re–P. The net effect is twin isomerization (Scheme 1).
An alternative pathway involving direct transfer of oxygen from
phosphorus to phosphorus is energetically highly unlikely since it
requires the synchronous dissociation of both P–O and Re–O
bonds.
The rate of the reaction 2
4 falls rapidly with increasing x
as expected from the statistics of polymethylene conformation.
The isomerization halts completely upon metal oxidation as in
2ϩ. Ongoing studies include scrutiny of the activation param-
eters of the 2
4 reaction and the search for other families that
display spacer regulated twin isomerization.
The rate of the isomerization reaction of eqn. (4) decreases
rapidly as the spacer length increases. The dependence on x is
exponential (Fig. 7) to a good degree. The number of possible
conformations of the dangling (CH2)xPPh2 fragment is indeed
expected to increase exponentially as x increases,15 but only a
few of the conformations will be spatially suited (proximal metal
and phosphine site) for the reaction to occur. We have previously
observed twin isomerizations similar to those reported here
in two cases of azoheterocyclic complexes where the process
took place exclusively in the x = 1 case.8,9 The eight compounds
reported here have provided the first opportunity to observe the
isomerization process in the domain of x spanning 1–4.
Experimental
The [ReL(O)Cl3] complexes were prepared as before.11 HPLC
grade acetonitrile was used for electrochemical work and all
other chemicals and solvents were of reagent grade and were
used as received. Spectral measurements were carried out using
the following equipment: UV-vis, Shimadzu UV 1601 PC
spectrophotometer fitted with thermostated cell compartments
(sh is shoulder); IR (KBr disc), Perkin-Elmer L-0100 and
Nicolet Magna IR 750 Series II spectrometers; 1H NMR,
Bruker 300 MHz spectrometer (s, singlet; d, doublet; t, triplet; i,
ill-resolved and m, multiplet). A Perkin-Elmer 2400 Series II
elemental analyzer was used for microanalysis (C, H, N). Solu-
tion electrical conductivity was measured in methanol with a
Phillips PR 9500 bridge using a platinized electrode (cell con-
stant of 1.05). Electrochemical measurements were performed
under a nitrogen atmosphere using a CHI model 620A electro-
chemical analyzer, with a platinum working electrode. The
supporting electrolyte was tetraethylammonium perchlorate
(TEAP), and the potentials are referenced to the saturated
calomel electrode (SCE) without junction correction.
Synthesis of complexes
[ReL(OP(Ph)2(CH2)xP(Ph)2)Cl3] 2. These were prepared
by a general procedure: reaction of [ReL(O)Cl3] with excess
Ph2P(CH2)xPPh2 in dichloromethane solution. Details are given
below for a representative case.
[ReL1(OP(Ph)2CH2P(Ph)2)Cl3]. To a solution of [ReL1-
(O)Cl3] (65 mg, 0.13 mmol) in 10 cm3 dichloromethane was
added 150 mg (0.39 mmol) of Ph2PCH2PPh2. The resulting
solution was magnetically stirred for 3.5 h at room temperature,
and during this time the colour changed from yellow to violet.
The solution was then subjected to chromatography on a silica
gel column (25 × 1 cm, 60–120 mesh). Excess diphosphine was
eluted with benzene. The violet band that followed was eluted
with a benzene–acetonitrile (25 : 1) mixture. Solvent removal
from the eluate under reduced pressure afforded [ReL1(OP-
(Ph)2CH2P(Ph)2)Cl3] as a violet solid. Yield: 68% (Found: C,
50.08; H, 3.49; N, 3.08. Calc. for C37H30N2O2P2Cl3Re: C, 49.98;
H, 3.40; N, 3.15%). UV-vis [λmax/nm (ε/dm3 molϪ1 cmϪ1),
CH2Cl2 solution]: 812sh (1090), 730 (2850), 580 (2060), 547sh
(2110), 510 (2310), 389sh (2710), 305 (27870). IR(cmϪ1): 300,
Fig. 7 Exponential plot of rate constant versus diphosphine spacer
length for the isomerization reaction of [ReL(OP(Ph)2(CH2)xP(Ph)2)-
Cl3] in dichloromethane solution at 308 K. The L1 and L2 complexes are
represented by open (᭺) and filled (᭹) circles respectively.
Upon oxidation of the metal to the tetravalent state as in 2ϩ,
the isomerization process is completely arrested even when x = 1
which corresponds to maximum reactivity in the case of 2. Cou-
lometric reduction of 2ϩ to 2 reestablishes the isomerization
process. The lack of reactivity of 2ϩ could be a reflection of the
kinetic inertness of the d3 configuration in rhenium(). Other
factors are also expected to work in the same direction. Thus
rhenium() is a harder acceptor than rhenium() and oxygen
is a harder donor than phosphorus. This as well as the weaker
back-bonding ability of rhenium() as revealed by the struc-
tural data is expected to disfavour the attack of the metal by
the dangling phosphine function. On these grounds [ReIVL-
(OPPh3)Cl3]ϩ should also be unreactive towards substitution
by PPh3. However, the conditions required for converting 3 to
5 (eqn. (3)) are relatively drastic (excess phosphine, boiling
benzene) and under these conditions the tetravalent complex is
spontaneously reduced to [ReIIIL(OPPh3)Cl3] which then reacts
as in eqn. (3).
309, 332 (Re–Cl), 1127 (O–P), 1593 (C᎐N). 1H NMR [δ (J/Hz),
᎐
CDCl3 solution]: L1, 21.90 (d, J = 7.5, 1H), 10.90 (d, J = 7.8,
1H), 10.54 (t, J = 7.8, 1H), 10.23 (d, J = 6.3, 1H), 8.97 (t, J = 8.6,
1H), 8.19 (t, J = 7.2, 1H), 6.80 (t, J = 7.5, 1H), 6.17 (d, J = 7.8,
1H); Ph2PCH2PPh2, Ϫ9.77 (s, 2H, CH2), 7.86 (m, 2H), 7.56 (m,
2H), 7.36 (m, 2H), 7.19 (m, 2H), 6.77 (m, 2H), 6.64 (t, J = 7.5,
2H), 6.29 (m, 4H), 4.66 (t, J = 7.7, 2H), 4.36 (t, J = 8.0, 2H).
[ReL2(OP(Ph)2CH2P(Ph)2)Cl3]. Yield: 70% (Found: C,
49.00; H, 3.31; N, 3.02. Calc. for C37H30N2OP2SCl3Re: C, 49.09;
D a l t o n T r a n s . , 2 0 0 3 , 4 6 3 5 – 4 6 4 3
4639

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H, 3.34; N, 3.09%). UV-vis [λmax/nm (ε/dm3 molϪ1 cmϪ1),
CH2Cl2 solution]: 815sh (2260), 739 (4480), 585 (3190), 517
(3000), 475sh (2760), 398sh (3510), 328 (19610). IR(cmϪ1) : 305,
1H), 17.58 (t, J = 6.1, 1H), 10.54 (t, J = 6.6, 1H), 8.23 (d, J = 8.2,
2H), 7.11 (t, J = 8.4, 1H), 5.61 (t, J = 7.2, 1H); Ph2P(CH2)4PPh2,
Ϫ3.87 (m, 2H, CH2), Ϫ4.61 (m, 2H, CH2), Ϫ5.34 (m, 2H, CH2),
Ϫ7.69 (m, 2H, CH2), 8.84 (t, J = 8.1, 2H), 8.46 (i, 2H), 8.01
(i, 2H), 7.68 (m, 4H), 6.89 (i, 2H), 6.43 (m, 4H), 5.53 (m, 2H),
3.96 (m, 2H).
330 (Re–Cl), 1135 (O–P), 1591 (C᎐N). 1H NMR [δ (J/Hz),
᎐
CDCl3 solution]: L2, 28.95 (d, J = 7.8, 1H), 22.54 (d, J = 6.2,
1H), 22.15 (t, J = 6.5, 1H), 11.05 (d, J = 8.1, 1H), 10.72
(t, J = 7.5, 1H), 8.31 (t, J = 7.5, 1H), 7.78 (t, J = 7.5, 1H), 6.59
(d, J = 7.3, 1H); Ph2PCH2PPh2, Ϫ10.70 (s, 2H, CH2), 8.42
(t, J = 8.7, 4H), 8.08 (t, J = 7.4, 6H), 7.18 (m, 2H), 6.59
(t, J = 6.8, 2H), 6.42 (m, 2H), 6.34 (t, J = 7.5, 4H).
[ReL2(OP(Ph)2(CH2)4P(Ph)2)Cl3]. Yield: 76% (Found: C,
50.67; H, 3.89; N, 3.05. Calc. for C40H36N2OP2SCl3Re: C, 50.72;
H, 3.83; N, 2.96%). UV-vis (λmax/nm (ε/dm3 molϪ1 cmϪ1),
CH2Cl2 solution]: 812sh (2220), 740 (4520), 585 (3320), 519
(3080), 475sh (2800), 396sh (3410), 328 (20090). IR(cmϪ1): 303,
[ReL1(OP(Ph)2(CH2)2P(Ph)2)Cl3]. Yield: 69% (Found: C,
50.66; H, 3.50; N, 3.18. Calc. for C38H32N2O2P2Cl3Re: C, 50.53;
H, 3.57; N, 3.10%). UV-vis [λmax/nm (ε/dm3 molϪ1 cmϪ1),
CH2Cl2 solution]: 810sh (1110), 732 (2810), 578 (1870), 547sh
(2000), 508 (2170), 386sh (2380), 306 (26950). IR(cmϪ1) : 310,
307, 325 (Re–Cl), 1127 (O–P), 1593 (C᎐N). 1H NMR [δ (J/Hz),
᎐
CDCl3 solution]: L2, 29.64 (d, J = 7.8, 1H), 28.41 (d, J = 7.7,
1H), 22.64 (t, J = 6.2, 1H), 15.50 (d, J = 6.9, 1H), 13.32 (d,
J = 7.2, 1H), 10.54 (t, J = 7.7, 1H), 7.67 (t, J = 7.8, 1H), 6.56 (t,
J = 8.4, 1H); Ph2P(CH2)4PPh2, Ϫ4.56 (m, 2H, CH2), Ϫ5.32
(m, 2H, CH2), Ϫ5.75 (m, 2H, CH2), Ϫ6.62 (m, 2H, CH2), 8.1–
8.4 (m, 4H), 7.97 (d, J = 7.6, 4H), 7.87 (d, J = 7.0, 2H), 7.78
(t, J = 7.9, 2H), 7.48 (t, J = 8.1, 6H), 6.71 (i, 2H).
328 (Re–Cl), 1131 (O–P), 1593 (C᎐N). 1H NMR [δ (J/Hz),
᎐
CDCl3 solution]: L1, 27.57 (d, J = 6.1, 1H), 21.36 (d, J = 7.5,
1H), 11.05 (t, J = 7.7,1H), 10.45 (t, J = 7.5, 1H), 8.74 (t, J = 8.4,
1H), 8.07 (d, J = 6.1, 1H), 6.55 (d, J = 6.2, 1H), 5.83 (t, J = 6.4,
1H); Ph2P(CH2)2PPh2, Ϫ1.20 (m, 2H, CH2), Ϫ2.84 (m, 2H,
CH2), 8.83 (i, 2H), 8.38 (d, J = 7.8, 2H), 7.89 (m, 4H), 7.68 (d,
J = 6.1, 2H), 7.48 (m, 4H), 7.03 (t, J = 7.5, 2H), 6.89 (t, J = 7.3,
2H), 5.68 (t, J = 7.2, 2H).
[ReL(OPMeyPh3 ؊ y)Cl3] 3. The y = 0 and 1 complexes are
known.11 The y = 2 complexes were prepared similarly in 80%
yields.
[ReL2(OP(Ph)2(CH2)2P(Ph)2)Cl3]. Yield: 72% (Found: C,
49.72; H, 3.44; N, 2.95. Calc. for C38H32N2OP2SCl3Re: C, 49.65;
H, 3.51; N, 3.05%). UV-vis (λmax/nm (ε/dm3 molϪ1 cmϪ1),
CH2Cl2 solution]: 813sh (2080), 738 (4340), 584 (3040), 516
[ReL1(OPMe2Ph)Cl3]. (Found: C, 37.42; H, 3.06; N, 4.30.
Calc. for C20H19N2O2PCl3Re: C, 37.36; H, 2.98; N, 4.36%) UV-
vis (λmax/nm (ε/dm3 molϪ1 cmϪ1), CH2Cl2 solution]: 813sh (1040),
732 (2680), 576 (1830), 547sh (2090), 503 (2140), 388sh (2650),
319 (12900). IR(cmϪ1): 310, 331 (Re–Cl), 1130 (O–P), 1600
(2930), 475sh (2700), 396sh (3450), 328 (18530). IR(cmϪ1
:
301, 308, 329 (Re–Cl), 1136 (O–P), 1593 (C᎐N). 1H NMR
(C᎐N). 1H NMR [δ (J/Hz), CDCl3 solution]: L1, 25.47 (d,
᎐
᎐
[δ (J /Hz),CDCl3 solution]: L2, 23.83 (d, J = 8.1, 1H), 23.18 (t,
J = 6.3, 1H) 23.05 (d, J = 6.1, 1H), 11.52 (d, J = 8.1, 1H), 10.77
(t, J = 7.7, 1H), 9.12 (i,1H), 7.64 (t, J = 7.2, 1H), 7.04 (t, J = 7.7,
1H); Ph2P(CH2)2PPh2, Ϫ2.45 (m, 2H, CH2), Ϫ2.77 (m, 2H,
CH2), 9.12 (m, 2H), 8.27 (t, J = 7.2, 2H), 8.06 (d, J = 7.4, 4H),
7.94 (t, J = 7.5, 4H), 7.36 (i, 2H), 6.91 (t, J = 7.4, 2H), 5.69 (t,
J = 7.1, 2H), 5.24 (m, 2H).
J = 7.8, 1H), 22.92 (d, J = 7.8, 1H), 22.23 (t, J = 6.5, 1H), 11.07
(t, J = 7.4, 1H), 9.65 (d, J = 6.3, 1H), 8.39 (t, J = 6.9, 1H), 6.17 (t,
J = 8.1, 1H), 2.36 (d, J = 8.1, 1H); PMe2Ph, Ϫ1.49 (s, 3H,
PCH3), Ϫ3.19 (s, 3H, PCH3), 10.80 (t, J = 7.8, 2H), 7.86 (t,
J = 7.7, 1H), 7.14 (d, J = 7.8, 2H).
[ReL2(OPMe2Ph)Cl3]. (Found: C, 36.40; H, 2.98; N, 4.29.
Calc. for C20H19N2OPSCl3Re: C, 36.45; H, 2.91; N, 4.25%) UV-
vis (λmax/nm (ε/dm3 molϪ1 cmϪ1), CH2Cl2 solution]: 815sh (2480),
742 (4690), 586 (3340), 515 (3140), 475sh (2950), 396sh (3730),
329 (20630). IR(cmϪ1): 302, 309,327 (Re–Cl), 1131 (O–P),
1593 (C᎐N). 1H NMR [δ (J/Hz), CDCl solution]: L2, 29.68 (d,
[ReL1(OP(Ph)2(CH2)3P(Ph)2)Cl3]. Yield: 71% (Found: C,
51.16; H, 3.66; N, 3.11. Calc. for C39H34O2N2P2Cl3Re: C, 51.07;
H, 3.74; N, 3.05%). UV-vis (λmax/nm (ε/dm3 molϪ1 cmϪ1),
CH2Cl2 solution]: 812sh (1180), 734 (2800), 579 (1960), 546sh
(2090), 514 (2230), 387sh (2520), 305 (26520). IR(cmϪ1): 302,
᎐
3
J = 7.8, 1H), 22.79 (t, J = 6.3, 1H), 22.21 (d, J = 6.4, 1H), 11.32
(t, J = 7.7, 1H), 11.16 (d, J = 9.0, 1H), 9.3–9.4 (m, 2H), 8.16 (d,
J = 7.5, 1H); PMe2Ph, Ϫ2.08 (s, 3H, PCH3), Ϫ2.12 (s, 3H,
PCH3), 8.45 (t, J = 7.8, 2H), 8.3–8.4 (m, 3H).
310, 331 (Re–Cl), 1128 (O–P), 1590 (C᎐N). 1H NMR [δ (J/Hz),
᎐
CDCl3 solution]: L1, 25.51 (d, J = 7.8, 1H), 21.72 (d, J = 7.8,
1H), 10.89 (t, J = 7.7, 1H), 10.53 (t, J = 7.7, 1H), 8.81 (i, 1H),
7.90 (t, J = 7.7, 1H), 6.63 (t, J = 7.9, 1H), 6.28 (d, J = 8.0, 1H);
Ph2P(CH2)3PPh2, Ϫ1.86 (m, 2H, CH2), Ϫ3.11 (m, 2H, CH2),
Ϫ4.14 (m, 2H, CH2), 8.53 (t, J = 7.8, 2H), 8.08 (t, J = 7.2,
2H), 7.80 (m, 2H), 7.55 (t, J = 7.1, 2H), 7.2–7.3 (m, 4H), 6.89
(t, J = 7.5, 2H), 6.51 (t, J = 6.7, 2H), 6.34 (t, J = 7.5, 2H), 6.08
(t, J = 8.6, 2H).
[ReL(P(Ph)2(CH2)xP(O)(Ph)2)Cl3] 4. The general procedure
consisted of simply leaving a dichloromethane solution of
[ReL(OP(Ph)2(CH2)xP(Ph)2)Cl3] to isomerize at room temper-
ature (≈298 K) in a stoppered flask for 1, 2, 4 and 5 days (L = L1)
and 2, 3, 5 and 7 days (L = L2) for the cases of x = 1, 2, 3 and 4
respectively. Procedural details are given below for a represent-
ative case.
[ReL2(OP(Ph)2(CH2)3P(Ph)2)Cl3]. Yield: 73% (Found: C,
50.29; H, 3.60; N, 2.90. Calc. for C39H34N2OP2SCl3Re: C, 50.19;
H, 3.67; N, 3.00%). UV-vis (λmax/nm (ε/dm3 molϪ1 cmϪ1),
CH2Cl2 solution]: 812sh (2290), 739 (4420), 585 (3170), 517
(2990), 475sh (2760), 396sh (3460), 328 (18280). IR(cmϪ1): 304,
[ReL1(P(Ph)2CH2P(O)(Ph)2)Cl3]. A 75 mg (0.08 mmol)
sample of [ReL1(OP(Ph)2CH2P(Ph)2)Cl3] was dissolved in 25
cm3 of dichloromethane, and the solution was left for 24 h. It
was then subjected to chromatography on a silica gel column. A
green band was eluted with a benzene–acetonitrile (25 : 10)
mixture. Solvent removal under reduced pressure afforded
[ReL1(P(Ph)2CH2P(O)(Ph)2)Cl3] as a green solid which was
dried under vacuum over fused CaCl2. Yield: 91% (Found: C,
49.90; H, 3.48; N, 3.28. Calc. for C37H30N2O2P2Cl3Re: C, 49.98;
H, 3.40; N, 3.15%). UV-vis [λmax/nm (ε/dm3 molϪ1 cmϪ1),
CH2Cl2 solution]: 679 (1730), 516 (820), 484sh (900), 445 (1180),
414 (1730), 317 (8130). IR(cmϪ1): 312, 320 (Re–Cl), 1195 (P–O),
332 (Re–Cl), 1125 (O–P), 1603 (C᎐N). 1H NMR [δ (J/Hz),
᎐
CDCl3 solution]: L2, 28.20 (d, J = 7.8, 1H), 22.62 (t, J = 6.2,
1H), 22.33 (d, J = 7.3, 1H), 10.97 (d, J = 8.3, 1H), 10.39 (t,
J = 7.7, 1H), 8.22 (t, J = 7.5, 1H), 8.01 (t, J = 7.5, 1H), 7.93 (d,
J = 8.2, 1H); Ph2P(CH2)3PPh2, Ϫ3.37 (m, 2H, CH2), Ϫ4.46 (m,
2H, CH2), Ϫ6.76 (m, 2H, CH2), 8.89 (i, 2H), 7.81 (m, 6H), 7.49
(t, J = 7.4, 4H), 7.30 (i, 2H), 7.21 (t, J = 8.1, 4H), 6.43 (t, J = 8.6,
2H).
[ReL1(OP(Ph)2(CH2)4P(Ph)2)Cl3]. Yield: 73% (Found: C,
51.50; H, 3.82; N, 3.09. Calc. for C40H36N2O2P2Cl3Re: C, 51.59;
H, 3.90; N, 3.01%). UV-vis (λmax/nm (ε/dm3 molϪ1 cmϪ1),
CH2Cl2 solution]: 815sh (1150), 735 (2770), 579 (1930), 547sh
(2040), 512 (2170), 384sh (2500), 306 (24500). IR(cmϪ1): 301,
1
1592 (C᎐N). H NMR [δ (J/Hz), CDCl solution]: L1, 18.82
᎐
3
(t, J = 6.3, 1H), 17.59 (d, J = 8.1, 1H), 16.44 (d, J = 6.5, 1H), 8.37
(t, J = 7.5, 1H), 6.07 (d, J = 7.8, 1H), 5.47 (t, J = 7.8, 1H), 0.86
(d, J = 7.8, 1H), Ϫ3.81 (t, J = 8.2, 1H); (Ph)2PCH2P(O)(Ph)2,
Ϫ2.85 (m, 2H, CH2), 19.53 (d, J = 7.2, 2H), 18.63 (d, J = 7.3,
2H), 10.33 (t, J = 7.1, 2H), 10.09 (t, J = 7.7, 2H), 9.43 (t, J = 6.9,
308, 327 (Re–Cl), 1127 (O–P), 1587 (C᎐N). 1H NMR [δ (J/Hz),
᎐
CDCl3 solution]: L1, 21.43 (d, J = 7.5, 1H), 21.22 (d, J = 7.5,
D a l t o n T r a n s . , 2 0 0 3 , 4 6 3 5 – 4 6 4 3
4640

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2H), 8.91 (t, J = 7.8, 2H), 8.17 (m, 2H), 7.62 (t, J = 7.2, 2H), 7.48
(m, 2H), 6.95 (t, J = 6.8, 2H).
1193 (P–O), 1607 (C᎐N). 1H NMR [δ (J/Hz), CDCl solution]:
᎐
3
L1, 24.25 (d, J = 7.8, 1H), 11.19 (t, J = 6.3, 1H), 10.76 (t, J = 7.7,
1H), 10.62 (t, J = 7.8, 1H), 9.71 (d, J = 7.8, 1H), 9.51 (d, J = 8.1,
1H), 7.07 (d, J = 8.7, 1H), Ϫ11.94 (t, J = 7.5, 1H); (Ph)2P-
(CH2)4P(O)(Ph)2, 6.75 (m, 2H, CH2), 6.11 (m, 2H, CH2), 5.22
(m, 2H, CH2), 4.06 (m, 2H, CH2), 19.53 (i, 2H), 18.39 (d,
J = 7.5, 2H), 16.41 (t, J = 6.3, 2H), 10.55 (d, J = 7.8, 2H), 8.56
(m, 4H), 7.63 (d, J = 6.7, 4H), 7.41 (d, J = 6.0, 4H).
[ReL2(P(Ph)2CH2P(O)(Ph)2)Cl3]. Yield: 85% (Found: C,
49.02; H, 3.27; N, 3.03. Calc for C37H30N2OP2SCl3Re: C, 49.09;
H, 3.34; N, 3.09%). UV-vis [λmax/nm (ε/dm3 molϪ1 cmϪ1),
CH2Cl2 solution]: 707 (3240), 513 (1490), 460sh (1940), 419
(3220), 323 (13660). IR(cmϪ1): 311, 322 (Re–Cl), 1179 (P–O),
1
1591 (C᎐N). H NMR [δ (J/Hz), CDCl solution]: L2, 18.60
᎐
3
(d, J = 6.9, 1H), 17.87 (d, J = 7.2, 1H), 12.62 (d, J = 6.2, 1H),
9.51 (t, J = 7.4, 1H), 9.05 (t, J = 7.8, 1H), 6.52 (t, J = 7.7, 1H),
2.60 (d, J = 8.1, 1H), Ϫ2.23 (t, J = 7.7, 1H); (Ph)2PCH2P-
(O)(Ph)2, Ϫ2.76 (m, 2H, CH2), 18.10 (m, 2H), 10.22 (t, J = 7.5,
2H), 9.70 (t, J = 7.7, 2H), 8.16 (t, J = 7.4, 2H), 7.71 (m, 4H), 7.37
(t, J = 6.3, 2H), 7.21 (m, 4H), 7.13 (m, 2H).
[ReL2(P(Ph)2(CH2)4P(O)(Ph)2)Cl3]. Yield: 76% (Found:
C, 50.78; H, 3.84; N, 2.90. Calc. for C40H36N2OP2SCl3Re: C,
50.72; H, 3.83; N, 2.96%). UV-vis [λmax/nm (ε/dm3 molϪ1 cmϪ1),
CH2Cl2 solution]: 688 (3200), 510 (1430), 461sh (1940), 429
(2340), 329 (13650). IR(cmϪ1): 307, 325 (Re–Cl), 1170 (P–O),
1
1605 (C᎐N). H NMR [δ (J/Hz), CDCl solution]: L2, 24.70
᎐
3
[ReL1(P(Ph)2(CH2)2P(O)(Ph)2)Cl3]. Yield: 85% (Found:
C, 50.65; H, 3.50; N, 3.18. Calc. for C38H32N2O2P2Cl3Re: C,
50.53; H, 3.57; N, 3.10%). UV-vis [λmax/nm (ε/dm3 molϪ1 cmϪ1),
CH2Cl2 solution]: 678 (1790), 517 (920), 483sh (1030), 444
(1350), 401 (2030), 316 (9710). IR(cmϪ1): 309, 325 (Re–Cl), 1179
(d, J = 8.1, 1H), 17.88 (i, 1H), 17.39 (t, J = 6.6, 1H), 12.52
(d, J = 7.5, 1H), 9.61 (t, J = 7.8, 1H), 9.11 (t, J = 7.7, 1H), 6.44
(d, J = 8.1, 1H), Ϫ1.47 (t, J = 7.8, 1H); (Ph)2P(CH2)4P(O)(Ph)2,
4.20 (m, 2H, CH2), 2.32 (m, 2H, CH2), 2.02 (m, 2H, CH2), 0.86
(m, 2H, CH2), 7.70 (t, J = 9.1, 4H), 7.47 (m, 6H), 7.36 (m, 2H),
7.0–7.2 (m, 4H), 6.7–6.8 (m, 4H).
1
(P–O), 1604 (C᎐N). H NMR [δ (J/Hz), CDCl solution]: L1,
᎐
3
18.84 (d, J = 6.6, 1H), 17.09 (d, J = 7.8, 1H), 15.17 (d, J = 6.1,
1H), 8.39 (t, J = 6.7, 1H), 7.12 (t, J = 6.8, 1H), 6.74 (t, J = 7.5,
1H), 0.52 (t, J = 7.6, 1H), Ϫ3.18 (d, J = 7.5, 1H); (Ph)2-
P(CH2)2P(O)(Ph)2, 6.39 (m, 2H, CH2), 4.14 (m, 2H, CH2), 16.58
(d, J = 6.9, 2H), 15.57 (d, J = 6.9, 2H), 9.39 (t, J = 7.4, 2H), 9.08
(t, J = 7.4, 2H), 8.65 (m, 2H), 7.48 (m, 2H), 6.66 (t, J = 6.3, 2H),
5.9–6.1 (m, 2H), 5.57 (t, J = 7.8, 2H), 5.45 (t, J = 8.6, 2H).
[ReL2(P(Ph)2(CH2)2P(O)(Ph)2)Cl3]. Yield: 83% (Found:
C, 49.60; H, 3.58; N, 3.01. Calc. for C38H32N2OP2SCl3Re: C,
49.65; H, 3.51; N, 3.05%). UV-vis [λmax/nm (ε/dm3 molϪ1 cmϪ1),
CH2Cl2 solution]: 701 (3360), 512 (1920), 460sh (2720), 419
(3560), 324 (12970). IR(cmϪ1): 308, 332 (Re–Cl), 1191 (P–O),
[ReL(PMeyPh3 ؊ y)Cl3] 5. These were prepared by the reaction
of [ReL(OPMeyPh3 Ϫ y)Cl3] with excess PMeyPh3 Ϫ y in boiling
benzene. Details are given below for a representative case.
[ReL1(PMe2Ph)Cl3]. To a solution of [ReL1(OPMe2Ph)Cl3]
(70 mg, 0.10 mmol) in 30 cm3 benzene was added PMe2Ph (83
mg, 0.60 mmol), and the mixture was heated to reflux for 1 h.
The resulting solution was evaporated to dryness and the resi-
due was washed several times with hexane (to remove excess
PMe2Ph). The residue was dissolved in 5 cm3 dichloromethane
and was subjected to chromatography on a silica gel column. A
green band was eluted with a benzene–acetonitrile (25 : 10)
mixture. Solvent removal from the eluate under reduced pres-
sure afforded [ReL1(PMe2Ph)Cl3] as a green solid which was
dried under vacuum over fused CaCl2. Yield: 88% (Found: C,
38.38; H, 3.00; N, 4.59. Calc. for C20H19N2OPCl3Re: C, 38.32;
H, 3.05; N, 4.47%). UV-vis [λmax/nm (ε/dm3 molϪ1 cmϪ1),
CH2Cl2 solution]: 691 (2340), 518 (1480), 483sh (1720), 449
(2010), 385 (3160), 317 (14620). IR(cmϪ1): 306, 326 (Re–Cl),
1
1604 (C᎐N). H NMR [δ (J/Hz), CDCl solution]: L2, 18.57
᎐
3
(i, 1H), 17.82 (i, 1H), 12.56 (i, 1H), 9.50 (t, J = 7.5, 1H), 9.04
(t, J = 7.5, 1H), 6.53 (t, J = 7.5, 1H), 2.56 (d, J = 7.5, 1H), Ϫ2.30
(t, J = 7.7, 1H); (Ph)2P(CH2)2P(O)(Ph)2, Ϫ2.70 (m, 2H, CH2),
Ϫ3.71 (m, 2H, CH2), 18.04 (m, 2H), 12.20 (t, J = 6.8, 2H), 9.68
(t, J = 7.4, 2H), 8.14 (t, J = 7.4, 2H), 7.78 (m, 4H), 7.40 (t,
J = 8.0, 4H), 7.14 (i, 2H), 6.76 (d, J = 6.4, 2H).
[ReL1(P(Ph)2(CH2)3P(O)(Ph)2)Cl3]. Yield: 83% (Found:
C, 51.19; H, 3.86; N, 3.00. Calc. for C39H34N2O2P2Cl3Re: C,
51.07; H, 3.74; N, 3.05%). UV-vis [λmax/nm (ε/dm3 molϪ1 cmϪ1),
CH2Cl2 solution]: 675 (1690), 517 (1170), 482sh (1440), 443
(1850), 415 (2180), 315 (14110). IR(cmϪ1): 312, 327 (Re–Cl),
1160 (P–O), 1606 (C᎐N). 1H NMR [δ (J/Hz), CDCl solution]:
1600 (C᎐N). H NMR [δ (J/Hz), CDCl solution]: L1, 20.73
1
᎐
3
(t, J = 6.5, 1H), 19.95 (d, J = 6.3, 1H), 19.10 (d, J = 8.1, 1H), 9.17
(t, J = 7.5, 1H), 6.28 (d, J = 9.6, 1H), 5.68 (t, J = 7.8, 1H); 0.86
(d, J = 7.5,1H), Ϫ3.02 (t, J = 7.8, 1H); PMe2Ph, 3.94 (s, 3H,
PCH3), 3.14 (s, 3H, PCH3), 17.62 (d, J = 7.2, 2H), 9.42 (t, J =7.7,
2H), 8.69 (t, J = 7.5, 1H).
᎐
3
L1, 24.28 (d, J = 8.7, 1H), 17.62 (d, J = 8.1, 1H), 11.82 (d,
J = 7.8, 1H), 11.54 (t, J = 7.7, 1H), 9.46 (t, J = 7.4, 1H), 9.11 (t,
J = 7.4, 1H), 6.18 (d, J = 7.8, 1H), Ϫ0.26 (t, J = 7.7, 1H);
(Ph)2P(CH2)3P(O)(Ph)2, 3.85 (m, 2H, CH2), 3.05 (m, 2H, CH2),
2.49 (m, 2H, CH2), 19.58 (d, J = 6.1, 2H), 18.45 (d, J = 7.5, 2H),
16.49 (t, J = 6.5, 2H), 8.68 (t, J = 6.0, 2H), 8.59 (m, 2H), 8.16
(t, J = 7.7, 2H), 7.98 (d, J = 7.8, 2H), 7.83 (m, 2H), 7.69 (i, 2H),
7.52 (t, J = 6.5, 2H).
[ReL2(PMe2Ph)Cl3]. Yield: 87% (Found: C, 37.49; H, 3.12;
N, 4.30. Calc. for C20H19N2PSCl3Re: C, 37.36; H, 2.98; N,
4.36%). UV-vis [λmax/nm (ε/dm3 molϪ1 cmϪ1), CH2Cl2 solution]:
709 (3390), 529 (1670), 460sh (2050), 413 (3470), 328 (14030).
1
IR(cmϪ1): 308, 327 (Re–Cl) 1600 (C᎐N). H NMR [δ (J/Hz),
᎐
,
CDCl3 solution]: L2, 15.87 (d, J = 6.9, 1H), 15.27 (t, J = 6.4,
1H), 9.20 (d, J = 7.8, 1H), 7.4–7.6 (m, 2H), 5.93 (t, J = 8.1, 1H),
2.72 (d, J = 7.2, 1H), Ϫ5.29 (t, J = 6.4, 1H); PMe2Ph, 7.81 (s,
3H, PCH3), 7.17 (s, 3H, PCH3), 8.5–8.8 (m, 3H), 8.24 (t, J = 7.6,
2H).
[ReL2(P(Ph)2(CH2)3P(O)(Ph)2)Cl3]. Yield: 80% (Found:
C, 50.29; H, 3.77; N, 3.08. Calc. for C39H34N2OP2SCl3Re: C,
50.19; H, 3.67; N, 3.00%). UV-vis [λmax/nm (ε/dm3 molϪ1 cmϪ1),
CH2Cl2 solution]: 692 (3010), 512 (2350), 460sh (2970), 425
(3830), 329 (17560). IR(cmϪ1): 325 (Re–Cl), 1195 (P–O), 1610
[ReL1(PMePh2)Cl3]. Yield: 83% (Found: C, 43.50; H, 3.00;
N, 4.17. Calc. for C25H21N2OPCl3Re: C, 43.58; H, 3.07; N,
4.07%). UV-vis [λmax/nm (ε/dm3 molϪ1 cmϪ1), CH2Cl2 solution]:
686 (1780), 514 (870), 483sh (940), 447 (1090), 387 (1540),
322 (8450). IR(cmϪ1): 309, 327 (Re–Cl) 1600 (C᎐N). 1H NMR
(C᎐N). 1H NMR [δ (J/Hz), CDCl3 solution]: L2, 24.69 (d,
᎐
J = 8.4, 1H), 17.86 (i, 1H), 17.37 (t, J = 6.6, 1H), 12.51
(d, J = 7.8, 1H), 9.60 (t, J = 7.7, 1H), 9.09 (t, J = 7.7, 1H), 6.42
(d, J = 8.2, 1H), Ϫ1.49 (t, J = 7.7, 1H); (Ph)2P(CH2)3P(O)(Ph)2,
4.11 (m, 2H, CH2), 3.74 (m, 2H, CH2), 2.77 (m, 2H, CH2), 7.6–
7.7 (m, 4H), 7.53 (d, J = 7.6, 2H), 7.49 (m, 4H), 7.35 (m, 4H),
7.12 (m, 4H), 6.81 (d, J = 7.7, 2H).
᎐
,
[δ (J/Hz), CDCl3 solution]: L1, 20.18 (t, J = 7.1, 1H), 18.52
(d, J = 8.1, 1H), 17.51 (d, J = 6.3, 1H), 9.11 (t, J = 7.5, 1H), 6.27
(d, J = 7.8, 1H), 5.67 (t, J = 7.8, 1H), 1.41 (d, J = 7.8, 1H), Ϫ3.31
(t, J = 7.8, 1H); PMePh2, 3.08 (s, 3H, PCH3), 15.83 (d, J = 7.2,
2H), 14.87 (d, J = 6.9, 2H), 9.30 (t, J = 7.2, 2H), 8.99 (t, J = 7.8,
1H), 8.81 (t, J = 7.7, 1H), 8.59 (t, J = 7.6, 2H).
[ReL1(P(Ph)2(CH2)4P(O)(Ph)2)Cl3]. Yield: 80% (Found:
C, 51.50; H, 3.98; N, 2.90. Calc. for C40H36N2O2P2Cl3Re: C,
51.59; H, 3.90; N, 3.01%). UV-vis [λmax/nm (ε/dm3 molϪ1 cmϪ1),
CH2Cl2 solution]: 674 (1720), 517 (1180), 482sh (1450), 442
(1890), 414 (2230), 315 (14710). IR(cmϪ1): 310, 330 (Re–Cl),
[ReL2(PMePh2)Cl3]. Yield: 86% (Found: C, 42.68; H, 3.09;
N, 3.90. Calc. for C25H21N2PSCl3Re: C, 42.59; H, 3.00; N,
3.97%). UV-vis [λmax/nm (ε/dm3 molϪ1 cmϪ1), CH2Cl2 solution]:
705 (3480), 524 (1920), 463sh (2060), 414 (3580), 326 (14450).
D a l t o n T r a n s . , 2 0 0 3 , 4 6 3 5 – 4 6 4 3
4641

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1
IR(cmϪ1): 310, 330 (Re–Cl) 1604 (C᎐N). H NMR [δ (J/Hz),
N, 4.97%). UV-vis [λmax/nm (ε/dm3 molϪ1 cmϪ1), CH2Cl2 solu-
᎐
,
CDCl3 solution]: L2, 20.17 (t, J = 6.6, 1H), 18.51 (d, J = 8.4,
1H), 17.47 (d, J = 6.3, 1H), 8.99 (t, J = 8.0, 1H), 6.27 (d, J = 8.4,
1H), 5.57 (t, J = 8.1, 1H), 2.00 (d, J = 6.3, 1H), Ϫ3.31 (t, J = 7.8,
1H); PMePh2, 3.07 (s, 3H, PCH3), 12.83 (d, J = 7.2, 2H), 11.88
(d, J = 7.5, 2H), 9.31 (t, J = 7.6, 2H), 9.11 (t, J = 7.6, 2H), 8.51
(t, J = 7.4, 1H), 8.29 (t, J = 7.4, 1H).
tion]: 434sh (1390), 385sh (3300), 319 (8840), 297 (8850).
IR(cmϪ1): 326, 339 (Re–Cl), 1118 (O–P), 1613 (C᎐N), 1384
᎐
(N–O, NO3Ϫ). H NMR [δ, CDCl3 solution]: L2, 55.35 (1H),
1
33.09 (1H), 16.37 (1H), 11.44 (1H), 10.20 (1H), 8.63 (1H), 6.19
(1H), 4.23 (1H); PPh3, 8.41 (6H), 6.31 (3H), 5.23 (6H).
[ReL1(PPh3)Cl3]. Yield: 86% (Found: C, 47.90; H, 3.15; N,
3.85. Calc. for C30H23N2OPCl3Re: C, 47.98; H, 3.09; N, 3.73%).
UV-vis [λmax/nm (ε/dm3 molϪ1 cmϪ1), CH2Cl2 solution]: 685
(1930), 514 (980), 483sh (1060), 449 (1280), 399 (1920), 318
(9520). IR(cmϪ1): 310, 325 (Re–Cl) 1600 (C᎐N). 1H NMR
Rate measurements
The rate of the single oxygen atom transfer reaction of eqn. (2)
was determined spectrophotometrically (quartz cell, path
length 1 cm) in the case of Ph2P(CH2)4PPh2. A known excess of
the diphosphine was added to a solution of [ReL1(O)Cl3] (1.25
× 10Ϫ4 M) in dichloromethane at 308 K and the absorbance At
monitored for the peak at 737 nm as a function of time (t). The
time dependent spectra are characterised by isosbestic points at
425 and 491 nm. The absorbance Aα at 737 nm at the end of the
reaction (6 h) was also monitored. The calculations were per-
formed using Microcal Origin V 2.8 (E. Northampton, Micro-
cal Origin Inc., 1991) and GraFit, Data Analysis & Graphics
Program, V 3.00 (R. J. Leatherbarrow, Erithacus Software Ltd.,
1992). The observed rate constants kobs were determined from
the slope of the highly linear plot (correlation constant 0.990–
0.996) of ln(Aα Ϫ At) versus t. The rate constant k was obtained
from the linear plot (correlation constant 0.9999) of kobs versus
concentration of the diphosphine. The rate constant for the
reaction of [ReL2(O)Cl3] with the diphosphine was similarly
determined.
The rate of the twin isomerization process of eqn. (4) was
also followed spectrophotometrically at 308 K. Time dependent
absorbances At were measured at 579 nm and 585 nm for the L1
and L2 complexes respectively and Aα values were obtained
at the end of the reaction (1 to 7 days depending on L and x).
Rate constants were determined from the linear plots (corre-
lation constants 0.996–0.999) of –ln(At Ϫ Aα) versus t. Variable
concentration (1Ϫ4 × 10Ϫ4 M) studies carried out in the
cases of x = 1 revealed that the rate constants were independent
of concentration consistent with first order kinetics. The plot of
rate constants against diphosphine spacer length (x) follows a
single exponential decay pattern (Fig. 7) with reduced χ2 values
of ≈ 10Ϫ8 and ≈ 10Ϫ9 for L1 and L2 complexes respectively.
᎐
,
[δ (J/Hz), CDCl3 solution]: L1, 19.82 (t, J = 6.6, 1H), 18.19 (d,
J = 8.4, 1H), 15.98 (d, J = 6.3, 1H), 8.75 (t, J = 7.4, 1H), 6.12
(d, J = 8.7, 1H), 5.49 (t, J = 7.8, 1H), 0.94 (d, J = 7.8, 1H), Ϫ3.81
(t, J = 8.1, 1H); PPh3, 13.32 (d, J = 6.6, 6H), 8.80 (t, J = 7.3, 6H),
8.42 (t, J = 7.5, 3H).
[ReL2(PPh3)Cl3]. Yield: 85% (Found: C, 46.90; H, 2.98; N,
3.60. Calc. for C30H23N2PSCl3Re: C, 46.97; H, 3.02; N, 3.65%).
UV-vis [λmax/nm (ε/dm3 molϪ1 cmϪ1), CH2Cl2 solution]: 707
(3260), 526 (1910), 463sh (2170), 413 (3320), 326 (11610),.
1
IR(cmϪ1): 310, 325 (Re–Cl) 1600 (C᎐N). H NMR [δ (J/Hz),
᎐
,
CDCl3 solution]: L2, 18.85 (t, J = 6.3, 1H), 17.71 (d, J = 7.9,
1H), 11.54 (d, J = 5.2, 1H), 8.87 (t, J = 7.7, 1H), 8.03 (d, J = 7.7,
1H), 6.53 (t, J = 7.9, 1H), 2.02 (d, J = 7.7, 1H), Ϫ2.05 (t, J = 7.5,
1H); PPh3, 13.06 (d, J = 6.7, 6H), 8.76 (t, J = 7.3, 6H), 8.43 (t,
J = 7.3, 3H).
[ReL(OP(Ph)2CH2P(Ph)2)Cl3]NO3 2؉NO3؊. The two com-
pounds (L = L1, L2) were prepared by the same general pro-
cedure. The details for L = L1 are given below.
[ReL1(OP(Ph)2CH2P(Ph)2)Cl3]NO3. To
a solution of
[ReL1(OP(Ph)2CH2P(Ph)2)Cl3] (75 mg, 0.08 mmol) in 15 cm3
acetonitrile was added dilute aqueous HNO3 (0.1 M, 3 cm3) and
the solution was stirred at room temperature for 0.25 h. During
this time the solution color changed from violet to orange. Sol-
vent removal under reduced pressure afforded [ReL1(OP-
(Ph)2CH2P(Ph)2)Cl3]NO3 as an orange solid. The solid was
washed thoroughly with water to remove the adherent nitric
acid and then dried under vacuum over fused CaCl2. Yield: 61%
(Found: C, 46.60; H, 3.27; N, 4.33. Calc. for C37H30N3O5P2-
Cl3Re: C, 46.72; H, 3.18; N, 4.42%). UV-vis [λmax/nm (ε/dm3
molϪ1 cmϪ1), CH2Cl2 solution]: 443sh (800), 361sh (2760), 324
(13090), 311 (14090). IR(cmϪ1): 325, 337 (Re–Cl), 1115 (O–P),
1611 (C᎐N), 1384 (N–O, NO Ϫ). 1H NMR [δ, CDCl3 solution]:
Crystallography
Ϫ
Single crystals of the complexes 3a, 3bϩNO3 ؒ0.5CH2Cl2, 5a
᎐
3
L1, 54.22 (1H), 16.96 (1H), 15.86 (1H), 11.57 (1H), 10.14 (1H),
7.60 (1H), 6.34 (1H), 4.17 (1H); Ph2PCH2PPh2, 8.49 (4H), 7.95
(4H), 7.74 (4H), 7.50 (4H), 6.88 (4H), 6.12 (2H).
and 5bؒH2O were grown by slow diffusion of hexane into di-
chloromethane solutions of the respective compounds. During
synthesis all the vacuum dried complexes occur in a non-sol-
vated form, vide supra. Single crystal formation however
requires solvation in two of the four cases examined here. Data
were collected on a Nicolet R3m/V four circle diffractometer
with graphite monochromated Mo-Kα radiation (λ = 0.71073
Å) by the ω-scan technique in the range 3 ≤ 2θ ≤ 50Њ for com-
[ReL2(OP(Ph)2CH2P(Ph)2)Cl3]NO3. Yield: 60% (Found:
C, 45.99; H, 3.19; N, 4.20. Calc. for C37H30N3O4P2SCl3Re: C,
45.95; H, 3.13; N, 4.34%). UV-vis [λmax/nm (ε/dm3 molϪ1 cmϪ1),
CH2Cl2 solution]: 433sh (1340), 386sh (3080), 316 (8100), 296
(8380). IR(cmϪ1): 325, 338 (Re–Cl), 1118 (O–P), 1613 (C᎐N),
᎐
1384 (N–O, NO3Ϫ). H NMR [δ, CDCl3 solution]: L2, 54.67
pounds 3a, 3bϩNO3 ؒ0.5CH2Cl2 and 5bؒH2O and in the range
1
Ϫ
(1H), 18.84 (1H), 16.09 (1H), 15.03 (1H), 11.55 (1H), 10.21
(1H), 4.15 (1H), 2.52 (1H); Ph2PCH2PPh2, 8.34 (2H), 7.82 (4H),
7.65 (4H), 7.51 (4H), 7.39 (4H), 6.56(2H), 4.83 (2H).
3 ≤ 2θ ≤ 47Њ for compound 5a. In all the cases the data
were corrected for Lorentz-polarization and absorption.18 The
metal atoms were located from Patterson maps and the rest of
the non-hydrogen atoms emerged from successive Fourier syn-
thesis. The structures were refined by full-matrix least-squares
procedures on F 2. The non-hydrogen atoms were refined aniso-
tropically and the hydrogen atoms (excepting those in solvents
of crystallisation) were included in calculated positions. The
[ReL(OPPh3)Cl3]NO3 3؉NO3؊. The same procedure used for
2ϩNO3Ϫ was employed for 3ϩNO3Ϫ as well.
[ReL1(OPPh3)Cl3]NO3. Yield: 66% (Found: C, 43.40; H,
2.88; N, 5.01. Calc. for C30H23N3O5PCl3Re: C, 43.46; H, 2.80;
N, 5.07%). UV-vis [λmax/nm (ε/dm3 molϪ1 cmϪ1), CH2Cl2 solu-
tion]: 442sh (820), 361sh (2590), 323 (11690), 312 (12580).
Ϫ
dichloromethane molecule in 3bϩNO3 ؒ0.5CH2Cl2 is highly
disordered and could be only roughly modelled (four-fold dis-
order around one chlorine atom acting as a pivot). Calculations
were performed using the SHELXTLTM V 5.0319 program
package. Significant crystal data are listed in Table 6.
CCDC reference numbers 214947–214950.
IR(cmϪ1): 328, 340 (Re–Cl), 1117 (O–P), 1610 (C᎐N), 1384 (N–
᎐
1
O, NO3Ϫ). H NMR [δ, CDCl3 solution]: L1, 56.80 (1H), 34.54
(1H), 17.81 (1H), 12.88 (1H), 11.64 (1H), 10.07 (1H), 7.61 (1H),
5.67 (1H); PPh3, 9.86 (6H), 7.74 (3H), 6.75 (6H).
[ReL2(OPPh3)Cl3]NO3. Yield: 64% (Found: C, 42.70; H,
2.70; N, 4.83. Calc. for C30H23N3O4PSCl3Re: C, 42.64; H, 2.74;
See http://www.rsc.org/suppdata/dt/b3/b307834e/ for crystal-
lographic data in CIF or other electronic format.
D a l t o n T r a n s . , 2 0 0 3 , 4 6 3 5 – 4 6 4 3
4642

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Ϫ
Table 6 Crystal data for complexes 3a, 3bϩNO3 ؒ0.5CH2Cl2, 5a and 5bؒH2O
3bϩNO3 ؒ0.5CH2Cl2
5a
5bؒH2O
Ϫ
Complex
3a
Formula
M
C20H19N2OPSCl3Re
658.95
C30.5H24N3O4PSCl4Re
887.56
C20H19N2OPCl3Re
626.89
C25H23N2O2PCl3Re
706.97
System
Space group
Monoclinic
P21
Triclinic
P1
Monoclinic
P21/c
Monoclinic
C2/c
¯
a/Å
b/Å
c/Å
α/Њ
10.597(2)
8.445(2)
12.674(3)
90
96.20(3)
90
1127.6(4)
2
1.941
13.989(3)
14.769(3)
16.881(3)
86.26(3)
88.95(3)
75.15(3)
3364.1(12)
4
9.266(5)
14.394(4)
16.311(5)
90
101.40(3)
90
2132.6(14)
4
1.953
18.008(4)
8.481(2)
34.252(7)
90
94.65(3)
90
5214(2)
8
1.801
β/Њ
γ/Њ
U/Å3
Z
D/mg mϪ3
T/K
1.752
293
4.079
293
5.922
293
6.163
293
5.056
µ/mmϪ1
Unique reflections
R1, wR2[I>2σ(I )]
All data
2095
0.0281, 0.0694
0.0290, 0.0707
10539
0.0595, 0.1482
0.0739, 0.1710
3149
0.0405, 0.0920
0.0641, 0.1189
4580
0.0391, 0.1053
0.0461, 0.1263
9 S. Bhattacharyya, I. Chakraborty, B. K. Dirghangi and
A. Chakravorty, Chem. Commun., 2000, 1813.
Acknowledgements
10 X. L. R. Fontaine, E. H. Fowles, T. P. Layzell, B. L. Shaw and M. J.
Thornton-Pett, J. Chem. Soc., Dalton Trans., 1991, 1519.
11 J. Gangopadhyay, S. Sengupta, S. Bhattacharyya, I. Chakraborty
and A. Chakravorty, Inorg. Chem., 2002, 41, 2616.
12 K. Nakamoto, Infrared and Raman Spectra of Inorganic and
Coordination Compounds, Theory and Applications in Inorganic
Chemistry, Part A, John Wiley and Sons, Inc., New York, 5th edn.,
1997, p. 182.
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We thank the Department of Science and Technology, and
Council of Scientific and Industrial Research, New Delhi for
financial support. We are thankful to Prof. G. K. Lahiri and
Dr S. Chattopadhyay for help.
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D a l t o n T r a n s . , 2 0 0 3 , 4 6 3 5 – 4 6 4 3
4643