Binuclear pentamethylcyclopentadienyl rhodium(III) compounds with pyrazolate and thiolate bridging ligands

Ž

.

Journal of Organometallic Chemistry 551 1998 55–65

ž /

Binuclear pentamethylcyclopentadienyl rhodium III compounds with

1

pyrazolate and thiolate bridging ligands

a

b,2

Juventino J. Garcıa ^a,), Gerardo Baron , Alma Arevalo , Hugo Torrens , Daniel Carmona ,

´

b

b,2

Montserrat Esteban , Fernando J. Lahoz , Jose A. Lopez , Luis A. Oro

´

a

Departamento de Quımica Inorganica, Facultad de Quımica, UniÕersidad Nacional Autonoma de Mexico, 04510 Mexico, D.F., Mexico

´

b

Departamento de Quımica Inorganica, Instituto de Ciencia de Materiales de Aragon, UniÕersidad de Zaragoza–Consejo Superior de

´

InÕestigaciones Cientıficas, 50009 Zaragoza, Spain

´

Received 1 May 1997

Abstract

5

wŽ

.

Ž

.Ž

. x

Ž

Ž .

wŽ

Binuclear thiolato-bridged complexes of general formula h -C₅Me_{5 2}Rh₂m-Pz m-SR BF₄Pzspyrazolate; RsC₆F₅2a ,

2

5

Ž

.

Ž

.

Ž

..

p-C₆F₄H 2b , p-C₆H₄F 2c or C₆H₅2d have been prepared by reacting the hydroxo–pyrazolato-bridged compound h -

C₅Me_{5 2}Rh₂m-Pz m-OH BF₄with the corresponding thiol. Complexes 2a–d show two types of fluxionality: rotation around the

.

Ž

. Ž

.x

2

thiol C–S bond and isomerization among the three possible isomers in which the thiols occupy axial andror equatorial positions within

the Rh₂S₂metallacycle. These processes are studied by ¹H and ¹⁹F NMR spectroscopies. The crystal structures of 2b and 2d were

established by X-ray crystallography. Compound 2b crystallises in the monoclinic space group P2₁rn, with lattice parameters

˚

Ž .

as14.368 2 , bs18.252 2 , cs15.268 2 A, bs109.79 1 8 and Zs4. Complex 2d crystallises in a monoclinic lattice, space group

˚

Ž .

C2rc, with as48.723 5 , bs8.7503 8 , cs40.334 4 A, bs112.620 5 8 and Zs16. Both cationic dinuclear complexes exhibit very

similar molecular structures with analogous pseudo-octahedral environments for the rhodium centres. Each metal is bonded to a terminal

h⁵-C₅Me₅group and to three bridging ligands: two monodentate thiolates p-SC₆F₄H in 2b and SC₆H₅in 2d and a bidentate

pyrazolate group. The main structural dissimilarity affects the relative configuration of the thiolate phenyl substituents giving rise to syn

Ž

.

Ž

.

Ž

.

2b or anti 2d structures. q 1998 Elsevier Science S.A.

Keywords: Rhodium; Binuclear complexes; Pentamethylcyclopentadienyl; Pyrazolato; Thiolato

1. Introduction

The discovery of h -C₅Me₅MCl₂

replacement of the chlorine ligands occurs very easily,

with a marked tendency to form binuclear complexes.

On the other hand, several laboratories have studied

the ability of binucleating groups such as pyrazolate or

thiolate ligands for the preparation of binuclear rhodium

5

w

Ž

.

x₂

Ž

.

MsRh, Ir

w

x

by Maitlis 1,2 has provided a relevant milestone on the

development of organometallic chemistry and homoge-

neous catalysis for nearly three decades, resulting in

major advances in the understanding of these areas. The

h⁵-pentamethylcyclopentadienyl group is an excellent

protecting ligand towards rhodium and iridium, whilst

Ž

.

w

x

and iridium complexes containing the M m-Pz 3–5 ,

2

Ž

.

w x

Ž

.Ž

.

w²x

M₂m-SR

6 or M₂m-Pz m-SR 7 frameworks.

2

Furthermore, our laboratories have independently re-

ported the synthesis and reactivity of several pentameth-

ylcyclopentadienyl rhodium and iridium complexes con-

w

x

w

x

taining pyrazolato 8–11 or perfluorothiolato 12,13

groups as bridging ligands.

In this paper we report the synthesis and characteri-

)

Corresponding authors.

zation of a new family of cationic binuclear complexes

¹Dedicated to a spectacular scientist and a good friend and

colleague, Peter M. Maitlis, on occasion of his 65th birthday.

²Also corresponding author.

5

w

Ž

.

Ž

.Ž

.

x

of formula h -C₅Me_{5 2}Rh₂m-Pz m-SR BF₄that

2

shows an interesting fluxional behaviour in solution.

0022-328X

r

98

r

(

)

56

J.J. Garcıa et al.rJournal of Organometallic Chemistry 551 1998 55–65

´

2. Results and discussion

2.1. Synthesis of the compounds

5

w

Ž

.

Ž

.Ž

The compounds

h -C₅Me_{5 2}Rh₂m-Pz m-

.

x

Ž

.

SR BF₄, Pzspyrazolate were prepared from the

2

5

w

Ž

di-m -pyrazolato-m -hydroxo com plex

h -

w x

1 14 and thiol ac-

.

Ž

. Ž Ž .

.

x

C₅Me_{5 2}Rh₂m-Pz m-OH BF₄

2

Ž .

cording to Eq. 1 :

h⁵-C Me Rh₂m-Pz

m-OH BF q2HSR

.

Ž

.₂Ž

Ž

.

5

4

2

™

h⁵-C Me Rh₂m-Pz m-SR BF₄

Ž

. Ž

.

Ž

.

5

2

5

qHPzqH₂O,

RsC F 2a , p-C F H 2b ,

₅Ž

.

Ž

.

6

6 4

p-C H F 2c or C H 2d

₅Ž

1

Ž .

Ž

.

6

4

6

Most probably the reaction proceeds through inter-

5

w

Ž

.

Ž

.Ž

mediates of the types h -C₅Me_{5 2}Rh₂m-Pz m-

5

.Ž

.

x^q

w

Ž

.

Ž

. Ž

SR m-OH

SR

andror h -C₅Me_{5 2}Rh₂m-Pz m-

2

.

x^q

with only one bridging thiolate ligand. However

we have not detected any of them and, when the

reaction was carried out with only one equivalent of

thiol, a mixture of the corresponding complex 2 and

unreacted starting compound 1 was obtained. Conse-

quently, we assume that the rate of formation of com-

plexes 2 from the mono-thiolate-bridged intermediates

is greater than that of formation of the aforementioned

intermediates from the starting compound 1. Small

amounts of the previously described cation–anion com-

5

wŽ

Fig. 1. Molecular representation of the cationic complex h -

.

Ž

.Ž

. x^q

C₅Me_{5 2}Rh₂m-Pz m-S-p-C₆F₄H

with the labelling scheme

2

used. Hydrogens have been omitted for clarity.

structural determination. Figs. 1 and 2 display molecular

drawings for the cations of 2b and 2d, respectively.

Table 1 collects a list of selected bond distances and

angles for these complexes.

The molecular structures of the cations of 2b and 2d

are rather similar. In both cases two h -C₅Me₅Rh

5

w

Ž

.

₂Ž

. ₃xwŽ

m -S R h -

p le x e s

h -C M e _{5 2}R h

5

.

Ž

.

x

w

x

C₅Me₅Rh SR have also been observed 15,16 .

3

The new complexes are yellow-to-red crystalline

solids, stable at room temperature, soluble in

dichloromethane, chloroform and acetone and insoluble

or sparingly soluble in diethyl ether, hexane or toluene.

5

Ž

.

moieties are maintained together through a triple bridge:

Ž

They were characterised by elemental analysis see

1

Section 4 , IR and H, ¹⁹F and ¹³C spectroscopy and by

.

the X-ray crystal structure determinations on com-

pounds 2b and 2d. The IR spectra revealed the absence

Ž

.

of the n OH vibrations of the starting compound. The

¹H and ¹⁹F spectra, at room temperature, were consis-

tent with the proposed stoichiometries and indicated, in

all cases, that the complexes are fluxional. We will

analyse this behaviour in detail below.

5

[(

)

(

2.2. Molecular structures of

)( ) ]

h -C₅Me_{5 2}Rh₂m-

5

(

)

[(

h -

P z m -S-p-C ₆F₄H

B F₄

2b

and

2

)

(

)( ( )

C₅Me_{5 2}Rh₂m-Pz m-SC₆H₅BF₄2d

) ]

2

In order to obtain structural information helpful to

understand the different NMR fluxional behaviour ob-

served for the apparently analogous complexes 2b and

Ž

.

2d see below we carried out the X-ray solid state

analysis of these two compounds. Both crystal struc-

tures showed the presence of dinuclear cations and

disordered BF₄^yanions packed within normal Van der

Waals distances. In the case of 2d two crystallographi-

cally independent set of atoms were identified in the

5

wŽ

.

Ž

.Ž

Fig. 2. Molecular drawing of the cation h -C₅Me_{5 2}Rh₂m-Pz m-

.₂x^q

Ž .

SC₆H₅

of compound 2d with the numbering scheme used.

(

)

J.J. Garcıa et al.rJournal of Organometallic Chemistry 551 1998 55–65

57

´

Ž .

Ž

.

Fig. 3. Schematic representation along the Rh 1 –Rh 2 direction of the cationic complexes 2b a and 2d b showing the anti 2b and syn–exo

Ž

.

2d configuration of the thiolate phenyl groups.

Ž . Ž . Ž . Ž . Ž

angle C 24 –S 1 PPP S 2 –C 30 close to zero y5.8

a bidentate pyrazolate—coordinated as usual through its

two nitrogen atoms—and a couple of S-bonded bridg-

ing thiolate groups, a para-tetrafluorophenylthiolate in

2b and the unsubstituted phenylthiolate in 2d. Formally,

the metal centres exhibit pseudo-octahedral coordina-

tion geometries, being coordinated to the 6-electron

donor h⁵-C₅Me₅ring and to the three bridging ligands.

Although some statistically significant differences are

observed for the molecular parameters collected in Table

1, most of them are chemically irrelevant, neither if

compared between the different complexes 2b or 2d,

nor between the two crystallographically independent

molecules present in 2d.

Ž . .

and 11.0 7 8 , in the case of 2b the more voluminous

substituted C₆F₄H groups are disposed towards differ-

ent sides of the Rh₂S₂reference plane, showing a

Ž .

related torsional angle of y177.1 5 8. If referred to the

Rh₂S₂cyclic system, the different configurations ob-

Ž

.

served could be described under the syn–exo 2d or

3

Ž

.

anti 2b terminology. The different orientation of the

phenyl rings affects dramatically to the symmetry of the

Ž

.

complexes, conforming a C_2vstructure 2d or a C_s

molecule in the case of 2b.

The most evident differences between both cations

come from the distinct configuration of the thiolate

phenyl rings relative to the bridging system Fig. 3 .

While in 2d the two phenyl rings are situated at the

same side of the ideal Rh₂S₂plane with a torsional

³In the syn– exo configuration, the two SR groups occupy two

equatorial positions on the Rh₂S₂ring. One axial and one equatorial

substituents are present in the anti isomer. The third possibility, i.e.,

Ž

.

Ž

two axial substituents would be adopted in the syn– endo isomer see

.

Scheme 1 .

(

)

58

J.J. Garcıa et al.rJournal of Organometallic Chemistry 551 1998 55–65

´

Table 1

the two C₅Me₅terminal ligands to be nearly parallel

Ž . .

5

˚

Ž .

Ž

.

wŽ

.

Ž

Selected bond lengths A and angles deg for h -C₅Me_{5 2}Rh₂m-

Ž

5.6 3 8 , in 2b and 2d the greater steric requirements of

the pyrazolate force the inter-planar C₅Me₅–C₅Me₅

5

.Ž

. x

Ž

.

wŽ

. Ž

.Ž

m-Pz m-

2

Pz m-S-p-C₆F₄H BF₄2b and

h -C₅Me₅

2

a

. x .

Ž

SC₆H₅BF₄2d

2

Ž .

angle to increase to values of 27.1 3 8 in 2b or 26.9 2

2b

3.3902 6

2d

Ž .

3.3891 8

Ž .

and 26.7 3 8 in 2d. This structural modification reduces

Ž .

Ž

.

Ž .

Rh 1 PPPRh 2

3.4536 10

2.422 2

2.411 2

the available space in the bridging area opposite to the

Ž . Ž .

Ž .

2.382 2

Rh 1 –S 1

2.397 2

2.407 2

2.378 2

2.385 2

2.067 5

2.077 5

1.802 3

1.791 3

1.372 5

1.328 7

1.321 7

1.378 8

1.383 8

1.799 6

1.775 7

77.23 6

Ž

pyrazolate due to the proximity of the methyl groups

Ž . Ž .

Ž .

2.389 2

Rh 2 –S 1

Ž . ..

Ž

.

Ž

.

Ž

C 8 –C 10 and C 17 –C 19

and, consequently,

Ž . Ž .

Ž .

2.392 2

Rh 1 –S 2

3.431 2

Ž .

Ž . Ž .

Ž .

2.401 2

Rh 2 –S 2

2.418 2

favours a symmetric configuration with the two phenyl

groups moved away from this area; that happens in the

Ž . Ž .

Ž .

2.068 5

Rh 1 –N 1

2.081 6

2.085 6

1.802 4

1.803 4

1.379 7

1.329 9

Ž .

1.351 9

1.370 10

1.400 10

1.792 7

Ž .

1.774 7

81.59 7

Ž .

82.09 7

87.2 2

88.3 2

131.17 11

133.26 12

76.5 2

74.7 2

Ž . Ž .

Ž .

2.065 5

Rh 2 –N 2

Ž

.

syn–exo geometry 2d . However, in the case of 2b, the

presence of ortho fluoro substituents in the phenyl

groups would give rise in a syn–exo configuration to

short distances between flourine atoms and the pyrazo-

late, destabilizing this configuration and making the

anti geometry of lower energy. This qualitative pro-

posal is also corroborated by the dihedral angles be-

Ž . Ž .^b

Ž .

1.799 4

Rh 1 –G 1

Ž . Ž .

Ž .

1.801 4

Rh 1 –G 2

Ž . Ž .

Ž .

1.364 6

N 1 –N 2

Ž . Ž .

Ž .

1.337 7

N 1 –C 1

Ž .

Ž

.

Ž .

1.343 7

N 2 –C 23

Ž

.

Ž

.

Ž

Ž .

.

Ž .

1.375 8

C 21 –C 22

Ž

.

Ž .

1.353 8

C 22 –C 23

Ž .

Ž

.

Ž .

1.792 7

S 1 –C 24

Ž

tween the bridging planes calculated through Rh–

Ž .

Ž

Ž .

1.792 6

S 2 –C 30

Ž .

Ž . Ž .

Ž .

77.44 6

Ž .

Ž . Ž .

.

S 1 –Rh 1 –S 2

S 1 –Rh, Rh–S 2 –Rh and Rh–N 1 –N 2 –Rh . All

Ž .

77.14 6

S 1 –Rh 2 –S 2

76.90 5

84.54 14

86.87 13

the values in the C_2vstructure 2d are similar and close

Ž . Ž . Ž .

Ž .

Ž

.

Ž

.

S 1 –Rh 1 –N 1

88.24 14

Ž

Ž . .

to the ideal value of 1208 range 116.0–124.0 1 8 , the

Ž . Ž . Ž .

Ž

86.42 14

S 1 –Rh 2 –N 2

Ž . Ž . Ž .

Ž .

inter-thiolate dihedral angles being 124.0 and 124.5 1 8.

Ž

.

Ž

126.35 13

S 1 –Rh 1 –G 1

Ž . Ž . Ž .

130.38 10

128.15 10

In the case of the anti isomer 2b, the values affecting

Ž

128.18 13

S 1 –Rh 2 –G 2

Ž . Ž . Ž .

Ž .

Ž

Ž .

( ) ( )

S 2 –Rh 1 –N 1

88.53 13

86.88 13

84.1 2

Ž .

86.8 2

the S 2 thiolate are altered by opening the S 2 –S 1

Ž . Ž . Ž .

Ž

S 2 –Rh 2 –N 2

Ž . Ž . Ž .

Ž .

dihedral angle, 138.4 1 8, and a consequent closing of

( ) Ž .

Ž

.

Ž

.

S 2 –Rh 1 –G 1

Ž . Ž . Ž .

128.90 11

126.16 12

132.4 2

126.32 10

127.60 10

131.9 2

130.84 14

the S 2 –Pz one, 100.0 1 8, in a movement that allows

Ž

127.71 13

S 2 –Rh 2 –G 2

Ž

.

Ž

.

more space for the phenyl group C 30 –C 35 .

Ž . Ž . Ž .

Ž .

131.9 29

N 1 –Rh 1 –G 1

All the Rh–S bond distances are similar and reflect a

Ž . Ž . Ž .

Ž .

N 2 –Rh 2 –G 2

133.5 2

Ž .

132.4 9

Ž .

132.5 2

Ž . Ž . Ž .

Ž .

Ž

barely detectable asymmetry in the bridges see Table

Rh 1 –N 1 –N 2

119.3 5

120.0 4

119.8 4

Ž . Ž . Ž .

Ž .

Rh 2 –N 2 –N 1

120.2 4

Ž .

Rh 2 –N 2 –C 23 132.1 5

117.9 4

133.6 4

118.4 5

Ž .

133.6 5

˚

.

Ž .

1 . However the mean value in 2b, 2.421 1 A, is

Ž . Ž .

Ž .

Rh 1 –N 1 –C 21 132.4 5

˚

Ž .

slightly longer than that observed in 2d, 2.392 1 A.

Ž . Ž . Ž .

Ž

.

Ž .

133.3 4

Ž .

133.2 4

These distances compare well with those reported in the

Ž . Ž .

Ž

.

Ž .

N 1 –N 2 –C 23

107.5 6

Ž .

107.3 6

108.3 5

108.0 5

5

w

Ž

.

Ž

.

x^q

dinuclear cation

h -C₅Me_{5 2}Rh₂m-SC₆F

Ž . Ž .

.

Ž .

N 2 –N 1 –C 21

106.4 5

111.6 6

106.6 5

Ž .

⁵w ³

Ž

5

˚

Ž .

Ž

.

Ž

.

Ž .

Ž

Ž .

.

N 1 –C 21 –C 22 111.7 7

110.9 6

2.425 6 A or in the mononuclear counter anion h -

.

Ž

.

₃x^y

Ž

Ž .

Ž

Ž .

110.2 6

Ž .

104.2 6

N 2 –C 23 –C 22 109.4 7

110.7 6

Ž .

˚

.

C₅Me Rh SC F₅

2.414 9 A of the same com-

⁵w

x ⁶

Ž

.

Ž

.

Ž

.

Ž .

C 21 –C 22 –C 23 103.9 7

103.0 6

pound 15,16 . The bridging Rh–S–Rh angles in the

Ž . Ž . Ž . Ž .

Ž .

Rh 1 –S 1 –Rh 2 91.23 7

Rh 1 –S 2 –Rh 2 90.81 7

Rh 1 –S 1 –C 24 114.5 2

Rh 1 –S 2 –C 30 116.8 3

Rh 2 –S 1 –C 24 113.7 2

Rh 2 –S 2 –C 30 114.2 3

89.77 6

90.74 5

90.53 5

Ž .

90.00 6

5

w

Ž

.

Ž

.

₃x^q

homobridged complex h -C₅Me_{5 2}Rh₂m-SC₆F₅

Ž . Ž . Ž . Ž .

Ž

Ž . .

mean 87.0 3 8 are also comparable with values found

Ž . Ž .

Ž

.

Ž .

107.3 2

Ž .

112.3 6

Ž . Ž . Ž .

Ž

.

Ž .

Ž

Ž . .

111.3 2

107.5 2

in 2b 91.02 3 8 and 2d 90.26 3 8 . Nevertheless, these

Ž . Ž . Ž .

Ž

.

Ž .

114.2 2

113.2 2

110.6 2

Ž .

Rh–S distances are clearly longer than those observed

Ž . Ž . Ž .

Ž

.

114.6 2

5

III

Ž

.

in related h -C₅Me₅Rh dinuclear complexes where

^aTwo independent molecules were observed in the X-ray analysis of

the bridging system contains only a double thiolate

5

w

Ž

.

Ž

.

x

bridge, those are the cases of h -C₅Me₅Rh m-L

2d.

2

b

Ž .

˚

G 1 and G 2 represent the centroids of the two cyclopentadienyl

rings present in each molecule.

Ž

Ž .

.

Lso-phenylenebenzenethiolato 2.341 2 A and 4-

˚

Ž

Ž .

.

A

w

x

methoxibuta-1-3-diene-1-thiolato 2.357 1

17 .

These later complexes exhibit longer intermetallic dis-

tances range 3.515 1 –3.565 2 A than those observed

in 2b, 3.4536 10 A, or in 2d, 3.3902 6 and 3.3891 8

A, and as a result longer Rh–S–Rh angles range

˚

.

Ž

Ž .

˚

Ž .

Ž

.

Ž .

The whole cationic structures closely resemble the

related dinuclear complex

SC₆F₅

been substituted by a bidentate pyrazolate. A simple

comparison of this complex with the cations of 2b and

2d allows a sensible explanation for the different con-

figurations observed for 2b and 2d. While in the triply

thiolate bridged complex

5

˚

w

Ž

.

Ž

h -C₅Me_{5 2}Rh₂m-

w x

15 , in which a bridging SC₆F₅group has

.

₃x^q

Ž .

Ž . .

96.6 1 –99.5 1 8 .

Within the error associated to the structural analyses,

all the Rh–N bond lengths in 2b and 2d are statistically

˚

.

Ž

Ž .

identical range 2.065 5 –2.085 6 A . These distances

are comparable with those found in other dinuclear

5

III

w

Ž

.

Ž

.

h -C₅Me_{5 2}Rh₂m-

the three identical bridging ligands originate

pyrazolato-bridged h -C₅Me₅Rh complexes such as

₂x^q

Ž

Ž .

2.070 4 and

.

₃x^q

5

wÄ

Ž

.

4

Ž

.Ž

.

SC₆F₅

h -C₅Me₅Rh m-Pz m-PPh₂

2

(

)

J.J. Garcıa et al.rJournal of Organometallic Chemistry 551 1998 55–65

59

´

5

˚

Ž .

.

w

x

w

Ä

Ž

.

4 Ž

2

2.081 4

A

18 , and

h -C₅Me₅Rh m-3-Me-

.Ž

.

₂x^q

Ž

Ž .

˚

. w x

Pz m-MeO

2.082 7 A 14 , as well as in the

5

wÄŽ

h -

related di-m -pyrazolato com plexes

x^q

Ž

Ž .

˚

.

A

.

4

Ž

. Ž

.

C Me Rh m-Pz m-OH

average 2.092 4

2

⁵x w⁵

Ä

Ž

4

Ž

. Ž

.

x^q

Ž

Ž .

aÕ. 2.091 6

5

w

14 , h -C Me₅Rh m-Pz m-Cl

2

w ⁵

Ä

w

.

4

Ž²

. Ž

.

5

˚

.

w x

Ž

x^q

Ž

aÕ.

A

5 or

h -C₅Me₅Rh m-Pz m-PPh₂

2

˚

Ž .

.

x

2.092 2 A 19 . On the other hand, if we compare the

separations between the metal atoms and the centroids

Ž

Ž .

of the C₅Me₅rings aÕs. 1.802 3 for 2b and 1.798 2

˚

.

A for 2d with those of the latter related complexes, it

seems that these Rh–C₅Me₅centroid distances Rh–

G 1 and Rh–G 2 are fairly sensitive to the steric

Ž

Ž .

Ž ..

requirements of the bridging ligands; that is, the shortest

5

w

Ä

Ž

.

4 Ž

distances were found for h -C₅Me₅Rh m-3-Me-

2

5

.Ž

.

₂x^q

Ž

Ž .

.

w

x

wÄŽ

h -

˚

Pz m-M eO

1.773 4

A

14 ,

˚

.

A

.

4

Ž

. Ž

.

x^q

Ž

Ž .

w x

C₅Me₅Rh m-Pz m-Cl

1.777 2

5

and

2

w

Ä

Ž

.

4

Ž ²

. Ž

.

x^q

Ž

Ž .

.

5

˚

h -C₅Me₅Rh m-Pz m-OH

aÕ. 1.778 2 A

2

Scheme 1.

w

x

14 , intermediate separations were observed in 2b, 2d

5

w

Ä

Ž

.

4

Ž

.Ž

.

x^q

Ž

or in h -C₅Me₅Rh m-Pz m-PPh₂m-Cl

aÕ.

2

˚

. w x

Ž .

1.822 3 A 18 , while the longest distances were deter-

anti disposition for the two thiolate groups and the

angles between the two substituted phenyl rings and

5

wÄŽ

h -

mined for the phosphido-bridged complexes

₂x^q

Ž

˚

Ž . . w x

aÕ. 1.876 5 A 18

.

4

Ž

.Ž

4

.

Ž . Ž Ž ..

C Me₅Rh m-Pz m-PPh₂

their respective Rh–S–Rh planes are 71.3 2 S 1 and

2

⁵w

Ä

Ž

.

Ž

. Ž

.

x^q

Ž .

Ž

aÕ. 1.858 2

5

Ž . Ž Ž ..

or h -C₅Me₅Rh m-Pz m-PPh₂

89.5 2 8 S 2 . On warming, from y110 to y558C,

2

˚

.

A

w x

19 .

while the two F_{or tho}signals at y129.3 and y135.9

ppm and the two F_metasignals at y159.4 and y160.3

ppm broadened and coalesced, the other two F_{or tho}and

F_metaresonances as well as the two F_parasignals re-

2.3. Fluxional behaÕiour

Ž

The dirhodium compounds 2a–d are fluxional in the

NMR time scale. Because of the different solution

behaviour, we will consider separately the ortho and

meta fluorine substituted thiolate derivatives 2a–b from

the p-substituted and unsubstituted thiolate 2c–d com-

pounds.

mained unchanged the evolution of the F_{or tho}signals is

collected in Scheme 2 . The rotation of one of the two

.

thiolate rings around its C–S bond would explain the

observed spectra: the ortho and meta fluorine nuclei

equilibrate while the para fluorine remains unaltered.

Relying on the static intramolecular interatomic dis-

tances, obtained in the X-ray structure of 2b, between

ortho fluorine atoms and hydrogens of the C₅Me₅

groups, it seems sensible to assume that the equatorial

2.3.1. Penta- and tetra-fluorophenyl thiolate complexes

2a and 2b

1

Ž

.

Ž

..

The room temperature H NMR spectrum of com-

phenyl ring labelled C 24 –C 29 is comparatively

less hindered by the C₅Me₅ligand to rotate along the

pound 2a, in CD₂Cl₂, consists of one singlet at 1.44

ppm due to the C₅Me₅groups and one triplet and one

doublet centred at 6.47 and 7.45 ppm, respectively,

assigned to the protons of the pyrazolate group. The

spectrum is essentially invariant over all the range of

temperature investigated. Only small changes in the

chemical shifts and in the resolution of the doublet and

triplet pyrazolate signals have been observed. However,

variable temperature ¹⁹F NMR studies show that the

complex is fluxional. At y1108C, in CD₂Cl₂, the ¹⁹F

NMR spectrum of compound 2a consists of ten well

resolved multiplets, one for each fluorine nucleus of the

molecule, along with the BF₄resonance. This low-tem-

perature-limiting spectrum is compatible with a static

anti structure with the planes of the phenyl groups of

the thiolate ligands being perpendicular to the Rh–Rh

Ž

.

Ž .

C 24 –S 1 bond and, consequently, to make equivalent

4

both ortho- and meta-fluorines of this phenyl group.

The F_{or tho}signals coalesce at y558C and from this

equilibration the free energy of activation DG^‡at the

coalescence temperature for the rotation process has

been calculated as 37.7 kJ mol^y1. Above y558C two

new processes become important. One of them implies

the equilibration of the two additional F_{or tho}and F_meta

and, interestingly, the other produces the equilibration

between the two F_para. At the highest temperature mea-

sured, q808C in a 1r1 vrv mixture of CDCl₃and

toluene-d⁸, the spectrum only shows three signals, one

4

Ž

.

In the case of the axial C₆F₄H group the F 31 atom exhibits

Ž

.

vector see Scheme 1 . In fact, the related derivative

Ž

.

Ž

short FPPPH C₅Me₅interatomic distances close to the limit of the

5

w

Ž

.

Ž

.Ž

.

x

Ž

.

h -C₅Me_{5 2}Rh₂m-Pz m-S-p-C₆F₄H BF₄2b ,

with the tetra-substituted S-p-C₆F₄H ligand, presents an

˚

.

sum of the van der Waals radii, 2.56 A with both C₅Me₅groups

2

˚

.

Ž Ž

.

Ž

.

Ž .

Ž

.

Ž

.

Ž .

F 31 PPPH 9c 2.65 3 and F 31 PPPH 18c 2.59 4 A .

(

)

60

J.J. Garcıa et al.rJournal of Organometallic Chemistry 551 1998 55–65

´

for each type of ortho, meta, and para fluorine atoms.

Consequently, we propose that the two new processes

consisted of the rotation of the second thiolate ring

with an anti disposition of the two thiolate ligands as

that found in the diffractometric analysis reported above.

Thus, at low temperature, in solution, the compound

retains the solid structure. However, on warming, two

of the F_{or tho}resonances coalesced at y558C. The calcu-

lated DG^‡value for the rotation process was 37.4 kJ

Ž Ž

.

Ž ..

around its C–S bond C 30 –S 2 and the isomeriza-

tion of the anti isomer to one or to the two possible syn

isomers depicted in Scheme 1 as syn–exo and syn–

endo. For the isomerization process it is possible to

calculate a DG^‡value of 53.9 kJ mol^y1at the coales-

cence temperature from the equilibration of the two

F_para. This process could involve cleavage of one of the

Rh–S–Rh bridges, rotation about the resulting terminal

Rh–S bond, and regeneration of the Rh₂S₂ring.

mol^y1. From the equilibration of the two H_para

‡

Ž

.

t_coalescences08C we obtain a DG value of 54.9 kJ

mol^y1for the isomerization process. Both DG^‡values

are comparable to the above reported for 2a supporting

that the fluxional processes involved would be also

similar.

The fluxional behaviour of the tetrafluorophenyl

derivative 2b is essentially similar to that described for

the pentafluorophenyl thiolate 2a. At y1108C, in

2.3.2. p-fluorophenyl and phenyl thiolate complexes 2c

and 2d

1

CD₂Cl₂, the H NMR spectrum shows, along with the

The H and ¹⁹F NMR spectra, in CD₂Cl₂, of the

pentamethylcyclopentadienyl and pyrazolate reso-

nances, two pseudoquintets centred at 7.11 and 7.38

ppm attributed to the two protons of the para position

of the two inequivalent thiolate ligands. The ¹⁹F NMR

spectrum, at the same temperature, besides the BF₄

resonance, consists of four F_{or tho}and four F_metareso-

nances. These spectra are the expected for a structure

p-fluorophenyl thiolate complex 2c show the presence

of three isomers in a relative proportion of ca. 70, 28,

and 2%, at y608C. The major isomer only contain one

type of phenyl thiolate ring and we assume that it is the

syn–exo isomer depicted in Scheme 1 on the basis of

the crystal structure determination carried out on the

related phenyl thiolate complex 2d and on the steric

5

8

wŽ

.

Ž

.Ž

. x

Ž

.

Ž

.

Scheme 2. F_{or tho}resonances region of the spectra of h -C₅Me_{5 2}Rh₂m-Pz m-SC₆F₅BF₄2a in CD₂Cl₂a–f or in CDCl₃rtoluene-d ,

2

Ž .

1r1, vrv g at selected temperatures 8C . The asterisks denote an impurity.

(

)

J.J. Garcıa et al.rJournal of Organometallic Chemistry 551 1998 55–65

61

´

Ž

arguments described along the structural discussion see

the solution and solid state properties of the dirhodium

compounds 2a–d. Thus, while, at low temperatures, the

anti isomer was the sole species observed for the perflu-

oro 2a and the tetrafluoro 2b derivatives, mixtures of

the three possible isomers were detected for the p-fluo-

rine substituted 2c or the unsubstituted 2d compounds,

the syn–exo isomer being the major component. More-

over, solid 2b has the anti disposition whereas the

syn–exo isomer was found in solid 2d in the crystallo-

graphic analyses carried out. The four complexes un-

dergo fluxional processes observable by NMR. Exclud-

ing the Rh₂S₂ring inversion, precluded by the presence

of the bridging pyrazolate ligand, two movements could

be envisaged as responsible for the dynamic behaviour

observed: rotation around the C–S thiolate bond and

isomerization. As expected, the first is less energetically

demanding for the ortho and meta unsubstituted com-

pounds 2c–d than for the tetra or pentafluoro thiolato

derivatives 2a–b. Furthermore, the rotation of the equa-

torial thiolate rings of the anti isomers of complexes 2a

and 2b, was more easily achieved than that of the axial

ones as indicated by the geometrical parameters deter-

mined in the structural analyses. The rotation of the

axial groups was observed by NMR at the same range

of temperatures than the isomerization process. In the

latter, at low temperatures, only the anti and syn–exo

isomers were involved but at higher energies also the

syn–endo isomer was concerned. Finally, from coales-

cence phenomena, the calculated values of the energy of

activation for the syn–exo–anti isomerization process

were greater by ca. 16 kJ mol^y1than that of the

rotation of the equatorial thiolate rings.

.

above . There are two types of thiolate rings in the 28%

abundant isomer and, consequently, it is the anti iso-

mer. The 2% of the mixture should be the syn–endo

isomer in which the two thiolate ligands are also equiva-

lent both occupying axial positions in the Rh₂S₂ring.

1

Additionally, the H NMR spectrum at y708C shows

an unique type of ortho and meta protons for the two

syn isomers and only two types of this kind of protons

for the anti isomer. Thus, even at y708C, the thiolates

of the three isomers are rapidly rotating about their C–S

bond. By diminishing the temperature, all the reso-

nances slowly broaden but, only the ortho protons of

the major isomer achieved the coalescence temperature

at y1308C, the lowest temperature of measurement

Ž

.

CD₂Cl₂rCFCl₃, 1r1, vrv as solvent . Thus, the rota-

tion is operating even at y1308C for the three isomers.

From y70 to y108C sharp and well resolved reso-

nances are observed in both proton and ¹⁹F spectra but,

above the later temperature, the equilibration between

the anti and syn–exo isomers was observed. From the

coalescence temperature of the two C₅Me₅singlets

y1

Ž

.

q358C a value of 64.9 kJ mol

was calculated for

the activation energy for this isomerization. Interest-

ingly, the signals attributed to the syn–endo isomer

remained sharp to q508C. Only above this temperature

its participation into the exchange process becomes

apparent. These proposals are strongly supported by the

evolution of the ¹⁹F NMR spectra with temperature

which follows completely compatible trends with the

proton NMR behaviour.

The fluxional behaviour of the phenyl derivative 2d

is similar to that described for the p-fluorophenyl thio-

late 2c. The X-ray molecular structure determination of

2d establish the presence in the solid state of the

4. Experimental details

Ž

.

syn–exo isomer see Fig. 2 and Scheme 1 . However,

the H NMR spectra recorded from y130 to q908C

1

reveal the presence of three isomers that we assign to

the syn–exo, anti, and syn–endo isomers depicted in

Scheme 1. At y508C the relative amount of each

isomer was ca. 59, 34 and 7%, respectively. We assume

that the major component is the syn–exo isomer instead

of the syn–endo on the basis of the X-ray crystal

structure determination. As in the p-fluorophenyl thio-

late case, the rotation of the thiolate rings operates in all

the range of temperature investigated and above q108C

the conversion between the syn–exo and anti isomers

takes place. The two C₅Me₅singlets coalesced at

q458C the corresponding DG^‡value being 66.8 kJ

All operations were carried out under inert atmo-

Ž

.

sphere high purity argon using standard Schlenk tech-

niques. Infrared spectra were recorded on Nicolet 550

and Perkin-Elmer 1615 FT-IR spectrophotometers. Car-

bon, hydrogen, and nitrogen analyses were performed

using a Perkin-Elmer 2400 microanalyzer. NMR spectra

were recorded on either a Varian UNITY 300 or a

13

Bruker AXR spectrometer using SiMe₄¹H, C or

Ž

.

Ž¹⁹

.

F as external standards. Chemical shifts are

13

CFCl₃

expressed in ppm upfield from SiMe₄¹H, C or

Ž¹⁹

Ž

.

F . Coupling constants J are given in Hertz.

CFCl₃

The variable temperature experiments were measured

from y1308C to y1108C in CD₂Cl₂rCFCl₃, 1r1,

vrv, from y110 to q408C in CD₂Cl₂and from q40

to q908C in CDCl₃rtoluene-d⁸, 1r1, vrv. Mass spec-

tra were measured on a VG Autospec double-focusing

mass spectrometer operating in the FAB^qmode. Ions

were produced with the standard Cs^qgun at ca. 30 kV,

mol^y1

.

3. Conclusions

The presence of fluorine substituents on the ortho

and meta positions of the thiolate rings strongly affects

Ž

.

and 3-nitrobenzyl alcohol NBA was used as matrix.

(

)

62

J.J. Garcıa et al.rJournal of Organometallic Chemistry 551 1998 55–65

´

5

w

Ž

.

Ž

. Ž

.x

Ž

.

Ž

.

The compound h -C₅Me_{5 2}Rh₂m-Pz m-OH BF₄

C₅Me₅RhSC₆F₄H, 7 , 305 C₅Me₅RhPz, 35 , 237

C₅Me₅Rh, 20 .

2

Ž .

w x

.

1

was prepared as previously described 14 . The

fluorothiophenols and thiophenol were obtained from

Aldrich, and used as received.

5

[(

)

(

)(

) ]

(

)

4.3. h -C₅Me_{5 2}Rh₂m-Pz m-S-p-C₆H₄F ₂BF₄2c

Ž

This complex was obtained analogously from 1 120

5

[(

)

(

)(

) ]

(

)

4.1. h -C₅Me_{5 2}Rh₂m-Pz m-SC₆F₅BF₄2a

2

.

Ž

mg, 0.168 mmol with the addition of HSC₆H₄F p-

. Ž

.

fluorothiophenol 0.336 mmol, 43.1 mg, 30 ml . In this

case when eluting the reaction mixture, a pretty small

amount of the green by-product was obtained and the

e lu te d w ith

dichloromethane:acetone 8:1 ; on drying it an orange

solid 2c 112 mg, 0.127 mmol, 74% was obtained.

Anal. Found: C, 47.3; H, 4.8; N, 3.0; S, 7.3%.

C₃₅H₄₁BF₆N₂Rh₂S₂requires C, 47.5; H, 4.7.; N, 3.2;

Ž

. Ž

The ligand HSC₆F₅pentafluorothiophenol 0.392

mmol, 78.5 mg, 60 ml was added to a solution of

complex

140 mg, 0.196 mmol in dichloromethane 10 ml

giving an orange–reddish solution, which was stirred

258C, 75 min . The reaction mixture was evaporated in

vacuo, giving an orange residue which was chromato-

graphed on a silica gel-60 70–230 mesh column.

Elution with dichloromethane gave a deep green frac-

tion which, when dried gave a purple–brownish solid

identified as

C₅Me₅Rh SC₆F₅, see Ref. 15,16 . When eluting

with dichloromethane:acetone 4:1 , an orange fraction

was obtained and, after drying, it gave a reddish solid

2a 188 mg, 0.183 mmol, 93% . Anal. Found: C, 40.95;

.

5

w

Ž

.

Ž

. Ž

.

x

Ž .

h -C₅Me_{5 2}Rh₂m-Pz m-OH BF₄

1

2

Ž

.

m a in fra c tio n

o ra n g e

Ž

.

Ž

.

Ž

.

Ž

.

Ž

.

Ž

.

1

Ž

.

S, 7.25%. NMR: H CD₂Cl₂, y608C, d syn–exo

3

Ž

.

Ž

.

isomer: 1.42 s, 30H, C₅Me₅, 6.59 t, J HH 2.1, 1H,

.

Ž

.

Ž

Pz , 6.31 m, 4H, o-H SC₆H₄F , 6.76 m, 4H, m-H

SC₆H₄F 7.70 d, 2H, Pz ; anti isomer: 1.33 s, 30H,

C₅Me₅, 6.58 t, 1H, Pz , 7.00 m, 2H o-H SC₆H₄F ,

7.20 m, 2H o-H SC₆H₄F , 7.56 m, 2H, m-H

SC₆H₄F , 7.73 m, 2H, m-H SC₆H₄F , 7.76 d, 2H,

Pz ; syn–endo isomer: 1.28 s, 30H, C₅Me₅, 7.07 m,

5

Ž

w

Ž

.

Ž

.

xwŽ

h -

h -C₅Me₅Rh₂m-SC₆F₅

3

.

Ž

.

x

²w

x.

.

Ž

.

Ž

3

.

Ž

.

Ž

.

Ž

.

Ž

.

Ž

.

Ž

.

Ž

.

Ž

19

H, 3.2; N, 2.9; S, 6.0%. C₃₅H₃₃BF₁₄N₂Rh₂S₂requires

C, 40.9; H, 3.2; N, 2.8; S, 6.2%. NMR: H CDCl₃,

.

Ž

.

m-H SC₆H₄F . F CD₂Cl₂, y608C, d syn–exo iso-

1

Ž

mer: y113.70 m; anti isomer y111.58 m, y113.53

3

.

Ž

.

Ž

.

RT, d 1.44 s, 30H, C₅Me₅, 6.47 t, J HH 2.5, 1H,

q

Ž

.

m; syn–endo isomer: y113.22 m. MS FAB : mrz

Pz , 7.74 d, 2H, Pz ; ¹⁹F CD₂Cl₂, y1108C, d

.

q

.

Ž

.

Ž

.

Ž

.

797 M , 100 , 669 M –SC₆H ₄F, 9 , 365

Ž

.

y121.97, y129.28, y130.00, y135.86 m, o-F ,

Ž

.

Ž

.

C₅Me₅RhSC₆H₄F, 18 , 305 C₅Me₅RhPz, 8 , 237

Ž

.

y149.38, y151.74 m, p-F , y158.56, y158.92,

Ž

.

C₅Me₅Rh, 20 .

y159.44, y160.31 m, m-F , y151.95 m, BF₄; ¹³C

Ž

.

Ž

.

Ž

5

Ž

.

Ž

.

Ž

.

[(

)

(

)(

) ]

(

)

CD₂Cl₂, q408C, d 8.95 s, C₅Me₅, 98.24 d, J RhC

4.4. h -C₅Me_{5 2}Rh₂m-Pz m-SC₆H₅BF₄2d

2

.

Ž

.

Ž

7.4, C₅Me₅, 108.64 s, C₄Pz , 139.97 s, C₃and C₅

Ž

This complex was prepared analogously from 1 130

.

Ž

.

Ž

Pz 108.21 t, J RhC 19.6, C_{i pso}136–152 o,m, p-

.

q

mg, 0.182 mmol with the addition of HSC₆H₅

thiophenol 0.364 mmol, 40.1 mg, 35 ml . The main

.

Ž

.

Ž

.

thiolate carbons . MS FAB : mrz 941 M , 100 ,

Ž

. Ž

.

q

Ž

.

Ž

.

741 M –SC₆F₅, 8 , 437 C₅Me₅RhSC₆F₅, 10 , 305

Ž

.

fra c tio n

o ra n g e

w a s e lu te d

w ith

Ž

.

Ž

.

C₅Me₅RhPz, 68 , 237 C₅Me₅Rh, 44 .

Ž

.

dichloromethane:acetone 10:1 and, on drying it, an

orange solid 2d 144 mg, 0.169 mmol, 92% was

obtained. Anal. Found: C, 49.5; H, 5.25; N, 3.2%.

Ž

.

5

[(

)

(

)(

) ]

(

)

4.2. h -C₅Me_{5 2}Rh₂m-Pz m-S-p-C₆F₄H ₂BF₄2b

C₃₅H₄₃BF₄N₂Rh₂S₂requires: C, 49.55; H, 5.1; N,

3.3% . NMR: H CD₂Cl₂, y508C, d syn–exo iso-

This complex was prepared analogously to 2a, from

1 130 mg, 0.182 mmol , with the addition of HSC₆F₄H

1

.

Ž

.

Ž

.

Ž

.

Ž

mer: 1.42 s, 30H, C₅Me₅, 6.39 d, J 7.6, 4H, o-H

Ž

. Ž

2,3,5,6-tetrafluorothiophenol 0.364 mmol, 66.3 mg,

3

.

Ž

.

Ž

SC₆H₅, 6.595 t, J HH 2.1, 1H, Pz , 7.03 st, 4H,

m-H SC₆H₅, 7.18 st, 2H, p-H SC₆H₅, 7.70 d, 2H,

Pz ; anti isomer: 1.32 s, 30H, C₅Me₅, 6.34 d, J 7.6,

4H, o-H SC₆H₅, 6.59 t, J HH 2.1, 1H, Pz , 7.77 d,

.

50 ml. . When eluting the reaction mixture on a silica

.

Ž

.

Ž

.

gel column, the first fraction green , was obtained in a

.

Ž

.

Ž

.

rather small amount than that of 2a and the main

3

.

Ž

.

Ž

.

fraction orange eluted with dichloromethane:acetone

.

Ž

.

2H, Pz ; syn–endo isomer: 1.28 s, 30H, C₅Me₅. MS

Ž

.

Ž

6:1 . After drying it an orange–reddish solid 2b 146

q

Ž

.

Ž

.

Ž

.

FAB : mrz 761 M , 100 , 652 M –SC₆H₅, 7 ,

.

mg, 0.147 mmol, 81% was obtained. Anal. Found: C,

42.5; H, 3.3; N, 2.9; S, 6.45%. C₃₅H₃₅BF₁₂N₂Rh₂₁S₂

requires C, 42.4; H, 3.55; N, 2.8; S, 6.5%. NMR: H

Ž

.

Ž

.

347 C₅Me₅RhSC₆H₅, 15 , 237 C₅Me₅Rh, 11 .

5

[(

h -

4.5. X-ray structure determination of

Ž

.

Ž

.

Ž

CD₂Cl₂, y708C, d 1.41 s, 30H, C₅Me₅, 6.56 t,

)

(

)(

) ]

(

)

C₅Me_{5 2}Rh₂m-Pz m-S-p-C₆F₄H BF₄2b and

3

2

Ž

.

Ž

.

J HH 2.1, 1H, Pz , 7.11 sq, J 7.4, 1H, p-H SC₆F₄H ,

5

[(

)

(

)(

) ]

(

)

h -C₅Me_{5 2}Rh₂m-Pz m-SC₆H₅BF₄2d

2

Ž

.

Ž

.

7.37 sq, J 7.6, 1H, p-H SC₆F₄H , 7.80 d, 2H, Pz ;

¹⁹F CD₂Cl₂, y1108C,

d

.

y121.56, y129.12,

4.5.1. Crystal data for 2b

Ž

.

y130.20, y137.17 m, o-F , y135.53, y135.80,

C₃₅H₃₅BF₁₂N₂Rh₂S₂; M s 992.40; monoclinic,

q

Ž

.

Ž

.

Ž

.

Ž . Ž .

15.268 2 A, bs109.79 1 8, Vs3767.4 8 A , Zs4;

y135.92, m, m-F , y150.47 m, BF₄. MS FAB :

space group P2₁rn; as14.368 2 , bs18.252 2 , cs

q

3

˚

Ž .

Ž

.

Ž

.

Ž .

mrz 905 M , 100 , 723 M –SC₆F₄H, 9 , 419

(

)

J.J. Garcıa et al.rJournal of Organometallic Chemistry 551 1998 55–65

63

´

D_cs1.750 Mg m^y3; F 000 s1976; l Mo–K_a

s

3

Ž

.

Ž

.

˚

Ž .

40.334 4 A, bs122.620 5 8, Vs14484 3 A , Zs

y1

16; D_cs1.556 Mg m^y3; F 000 s6880; l Mo–K_a

˚

Ž .

Ž

.

Ž

.

0.71073 A; ms1.076 mm ; Ts150.0 2 K.

s0.71073 A; ms1.074 mm^y1; Ts293 K.

˚

4.5.2. Crystal data for 2d

C₃₅H₄₃BF₄N₂Rh₂S₂; Ms848.47; monoclinic, space

4.5.3. Data collection and processing

Ž .

group C2rc; a s 48.723 5 , b s 8.7503 8 , c s

Suitable crystals for the X-ray determinations were

grown by slow diffusion of hexane into ethanolic solu-

tions of complexes 2b and 2d. An orange irregular plate

of approximate dimensions 0.25=0.15=0.06 mm was

used in the analysis of 2b; a yellow–orange prismatic

block, 0.38=0.18=0.12 mm, in the case of 2d. Inten-

sity data were collected on a Siemens-P4 diffractometer

using graphite monochromated Mo–K_aradiation. Cell

parameters were determined by least-squares refinement

Table 2

4

Selected atomic co-ordinates^a=10 and equivalent isotropic dis-

Ž

.

2

3

5

˚

Ž

.

Ž

wŽ .

placement parameters A =10 for the complex h -C₅Me₅

2

Ž

.Ž .

. x

Rh₂m-Pz m-S-p-C₆F₄H BF₄2b

2

x

y

z

U ^b

eq

Ž .

Rh 2

Ž .

3483.2 4

Ž .

6441.1 4

Ž .

24.1 2

Rh 1

Ž .

5829.7 4

y1950.8 4

6295.7 4

Ž .

y1912.9 4

Ž .

25.7 2

Ž .

4401 1

Ž .

5825 1

Ž .

25.9 5

S 1

S 2

5120 1

y1601 1

7465 1

Ž

.

Ž

.

from the 2u values of 58 2b or 52 2d accurately

Ž .

y2760 1

Ž .

26.6 5

Ž

.

centred reflections 20F2uF308 . A conventional

vr2u scan mode was applied for the measurement of

data in 2b, whereas the long length of two cell parame-

ters in 2d suggested a v-scan to be more appropriate. A

Ž .

29 2

N 1

4734 4

y1318 3

5359 4

Ž .

y1341 3

Ž .

24 2

N 2

3784 4

5385 4

Ž .

25 2

C 1

6831 5

y2384 4

5654 5

Ž .

y1640 4

Ž .

29 2

C 2

7097 5

5869 5

Ž .

Ž

Ž .

28 2

C 3

7340 5

y1541 40

6848 6

Ž

.

Ž

. Ž

total of 5950 2b or 11323 reflections 2d 4F2uF

Ž .

28 2

C 4

7287 5

y2248 4

7249 5

.

Ž

458 were collected; 4862 independent reflections R_int

Ž .

y2762 4

Ž .

29 2

C 5

6979 6

6518 6

Ž .

41 2

.

Ž

.

C 6

6548 6

y2725 4

4709 6

s0.059 in 2b and 9383 for complex 2d R_ints0.029

Ž .

38 2

C 7

7204 5

y1069 4

5211 5

were used in the analyses. A set of three standard

reflections were monitored along both data collections

as a check of crystal and instrument stability. The weak

intensity decay observed along data collection of 2b

Ž .

42 2

C 8

7734 6

y864 4

7397 5

Ž

Ž .

C 90

7605 5

Ž .

y2402 5

8268 5

Ž .

38 2

Ž

.

Ž .

C 10

C 11

C 12

C 13

C 14

C 15

C 16

C 17

C 18

C 19

C 20

C 21

C 22

C 23

C 24

C 25

6962 6

y3568 4

6634 6

45 2

Ž

Ž .

1891 5

y2073 5

5956 5

32 2

Ž .

Ž

Ž .

Ž

Ž .

Ž

.

2372 6

y2653 40

6591 6

31 2

2.4% was amended according to standard reflections.

Ž

Ž .

2882 5

Ž .

y2335 5

7460 6

Ž .

31 2

Data were corrected for Lorentz and polarization ef-

fects. A semiempirical correction for absorption, via

Ž

Ž .

2713 6

y1558 5

7373 6

36 2

Ž

Ž .

2118 5

y1411 5

6460 6

35 2

Ž .

Ž

c-scans, was also applied max. and min. trans. fact.

Ž

Ž .

1199 5

y2187 5

4974 5

49 3

.

w x

0.878 and 0.809 for 2b; 0.891 and 0.837 for 2d 20 .

Ž

Ž .

2229 6

Ž .

y3447 5

6383 7

Ž .

48 3

Ž

Ž .

3391 6

y2724 5

8344 6

52 3

Ž

Ž .

3023 6

y1007 5

8153 6

51 3

Ž .

4.5.4. Structure solution and refinement

Ž

Ž .

1690 6

y665 5

6077 6

49 2

The structures were solved by direct and Fourier

Ž

Ž .

.

Ž .

4700 6

Ž .

y95794

4594 5

Ž .

34 2

Ž

w x.

methods SIR92 21 and refined by full-matrix least-

Ž

Ž .

3764 6

y714 4

4113 5

36 2

Ž

w x.

squares SHELXL-93 22 . Atoms were refined isotrop-

ically first, and in subsequent cycles with anisotropic

thermal parameters for all the non-hydrogen atoms.

C₅Me₅hydrogen atoms in 2b were included in calcu-

lated positions, but those of the bridging ligands were

found from different Fourier maps; all hydrogens in this

molecule were refined riding on their respective carbon

Ž

Ž .

3192 5

y998 4

4622 5

31 2

Ž .

Ž

Ž .

y652 4

Ž .

5265 5

7783 5

22 2

Ž

Ž .

4719 6

y71 4

7311 5

29 2

Ž

.

Ž .

y164 2

Ž .

51 1

F 25

3994 3

6487 3

Ž

.

Ž .

7673 6

Ž .

40 2

C 26

4857 7

622 5

Ž

.

Ž .

Ž

.

Ž .

55 2

F 26

4249 4

1159 2

790 5

223 5

344 3

7160 30

Ž

.

Ž .

41 2

C 27

C 28

5547 6

8517 6

Ž

Ž .

45 2

6082 6

8977 6

Ž .

Ž

.

Ž .

70 2

F 28

6820 4

9815 3

Ž

atoms with two common thermal parameters one for

Ž

.

Ž .

38 2

C 29

5969 6

y472 4

8617 5

.

C₅Me₅and one for bridging groups . In the case of 2d,

Ž

.

Ž

Ž .

9152 3

Ž .

54 1

F 29

6563 30

y1012 3

all the hydrogens were included in calculated positions

and were refined in a similar way to that described for

2b. In both structures, the BF₄^yanions exhibit static

disorder. Each independent anion was modeled on the

basis of two BF₄^ygroups with restricted interatomic

distances and complementary occupancy factors. A

weighting scheme was used in the final steps of the

Ž

.

Ž .

C 30

4559 5

y3641 4

6345 5

23 2

Ž

Ž .

y3775 4

Ž .

C 310 4969 6

7283 5

31 2

Ž

.

Ž .

F 31

5320 3

y3220 2

7882 3

39 1

Ž

.

Ž .

y4478 5

Ž .

53 2

C 32

5055 6

Ž .

7633 6

Ž

Ž .

54 1

F 320 5465 4

y4570 5

8566 3

Ž

.

Ž .

42 2

C 33

4744 6

y5066 4

7069 6

Ž

.

Ž .

y4934 5

Ž .

42 2

C 34

4343 6

6133 6

Ž

.

Ž .

5533 4

Ž .

70 2

F 34

4035 4

y5509 3

2

refinements: w^y1s s F_oq a P

where Ps F_o

Ž

.

Ž .

34 2

w

²Ž

.

Ž

.

x

Ž

C 35

4260 6

y4248 4

5769 6

Ž .

4841 3

2

Ž

.

Ž .

y4158 2

Ž .

53 1

F 35

3861 3

.

Ž

.

q2F r3 with as0.0313 2b and 0.0135 2d . Re-

c

Ž

.

Ž

2

finements converged to R F s0.0401 for 2865 ob-

^aThe atomic co-ordinates of the disordered anions have been omitted.

^bU is defined as one third of the trace of the orthogonalized U_ij

Ž ..

Ž

.

served reflections, IG2s I and wR F s0.0876

eq

Ž

.

Ž

for 2b, and R F s0.0337 5328 observed reflections,

tensor.

(

)

64

J.J. Garcıa et al.rJournal of Organometallic Chemistry 551 1998 55–65

´

Table 3

Ž

.

Table 3 continued

4

Selected atomic co-ordinates^a=10 and equivalent isotropic dis-

Ž

.

x

y

z

U ^b

eq

2

3

˚

Ž

.

placement parameters A =10 for the two independent molecules

of the complex h -C₅Me_{5 2}Rh₂m-Pz m-SC₆H₅BF₄2d

5

Ž

.

Ž .

Ž

.

Ž .

50 2

C 64

Ž

4660 2

4661 1

4499 2

4296 2

4469 2

4814 1

4802 2

3453 2

3680 2

3956 2

4077 2

3990 2

4109 2

4318 2

4400 2

4289 2

y3206 10

6000 2

5759 2

5017 2

5052 2

5916 2

6434 2

5886 2

4965 2

4934 2

5134 2

6239 2

6106 2

6371 3

6762 3

6891 2

6644 2

wŽ .

.

Ž

.Ž

. x

Ž

2

Ž .

43 2

C 65

y4381 8

x

y

z

U ^b

eq

Ž

Ž .

95 3

C 66

y4471 9

Ž .

y1049 9

Ž .

Rh 1

Ž .

3939.3 1

3544.8 1

Ž .

y709.7 6

Ž .

7401.7 1

Ž .

33.0 1

8391.5 1

Ž

Ž .

100 3

C 67

Ž .

32.5 1

Rh 2

y1127.4 6

Ž

Ž .

101 3

C 68

y386 8

Ž .

y3374 9

Ž .

y2420 2

Ž .

7936 1

Ž .

35.4 4

S 1

3531 1

7919 1

Ž

Ž .

89 3

C 69

Ž .

36.9 4

S 2

4101 1

y1084 2

Ž

Ž .

84 3

C 70

y5948 8

Ž .

y7005 8

Ž .

986 6

Ž .

35 1

N 1

3626 1

8027 1

Ž

Ž .

57 2

C 71

Ž .

35 1

N 2

3487 1

893 6

7628 1

Ž

Ž .

63 2

C 72

y7807 8

Ž .

y6939 8

Ž .

51 2

C 1

4208 2

524 9

8943 2

Ž

Ž .

52 2

C 73

Ž .

Ž

.

Ž .

58 2

C 2

3975 2

y446 11

8948 2

Ž

Ž .

.

Ž .

48 2

C 74

y5413 9

Ž .

Ž

Ž .

60 2

C 3

4052 2

y1976 10

8916 2

Ž

Ž .

62 2

C 75

y6893 9

Ž .

Ž

Ž .

55 2

C 4

4325 2

y1961 10

8882 2

Ž

Ž .

Ž

Ž .

80 3

C 76

y8087 10

Ž .

47 2

C 5

4428 2

y406 9

8909 2

Ž

Ž .

Ž

y7841 11

Ž .

87 4

C 77

Ž .

2219 9

Ž .

100 3

C 6

4247 2

9007 2

Ž

Ž .

Ž

Ž .

85 3

C 78

y6387 12

Ž .

Ž

.

Ž .

106 4

C 7

3703 2

27 10

9001 2

Ž

Ž .

y5149 9

Ž .

58 2

C 79

Ž .

115 4

C 8

3886 2

y3340 9

8951 2

Ž

Ž .

y2631 8

Ž .

41 2

C 80

3452 1

3228 1

3055 2

3101 2

3320 2

3500 2

4617 2

4372 2

3967 2

3807 2

4041 2

4449 2

Ž .

102 3

C 9

Ž

4492 2

y3356 9

8860 2

Ž

Ž .

45 2

C 81

y1510 8

.

Ž .

86 3

C 10 4729 1

88 9

8924 2

Ž

Ž .

Ž

.

Ž .

63 2

C 82

y1698 10

Ž

.

Ž .

39 2

C 11 3420 2

y486 8

6815 2

Ž

Ž .

Ž

y2963 10

Ž .

71 3

C 83

Ž

.

Ž .

45 2

C 12 3652 2

y1684 8

6960 2

Ž

Ž .

Ž

Ž .

76 3

C 84

y4054 10

Ž

.

Ž .

49 2

C 13 3525 2

y2975 8

Ž .

y2601 8

7046 2

Ž

Ž .

y3888 9

Ž .

61 2

C 85

Ž

.

Ž .

46 2

C 14 3198 2

6927 2

^aThe atomic co-ordinates of the disordered anions have been omitted.

Ž

.

Ž .

42 2

C 15 3132 2

y1093 8

6794 2

^bU is defined as one third of the trace of the orthogonalized U_ij

Ž

.

Ž .

56 2

eq

C 16 3454 2

1059 7

6685 2

tensor.

Ž

.

Ž .

65 2

C 17 3978 2

y1586 8

7006 2

Ž

.

Ž .

C 18 3688 2

y4499 8

7189 2

88 3

2

Ž

.

Ž .

y3676 8

Ž .

Ž ..

Ž

.

w x

C 19 2964 2

6943 2

72 2

IG2s I and wR F s0.0520 for 2d 22 . Atomic

Ž

.

Ž .

C 20 2810 1

y306 7

6621 2

Ž .

61 2

Ž .

scattering factors, corrected for anomalous dispersion,

Ž

.

Ž .

2282 8

C 21 3520 2

8092 2

53 2

w

x

were taken from Ref. 23 . Final atomic coordinates are

given in Tables 2 and 3. Additional material available

from the Cambridge Crystallographic Data Center com-

prises H-atom coordinates, thermal parameters and re-

Ž

.

Ž .

C 22 3316 2

3061 8

7746 2

64 2

Ž

.

Ž .

C 23 3309 2

2131 7

7464 2

43 2

Ž

.

Ž .

C 24 3165 1

y2083 8

7917 2

Ž .

38 2

Ž .

Ž

.

Ž .

C 25 2962 2

y850 9

7744 2

65 2

Ž

.

Ž .

Ž

.

Ž .

C 26 2701 2

y669 10

7784 2

84 3

Ž

.

maining bond lengths and angles CIF file .

Ž

.

Ž .

Ž

Ž .

C 27 2637 2

y1672 11

7981 2

83 3

Ž

.

Ž .

Ž

Ž .

C 28 2832 2

y2905 10

8149 2

Ž .

79 3

Ž .

Ž

.

Ž .

y3142 8

C 29 3090 2

8109 2

60 2

Acknowledgements

Ž

.

Ž .

519 9

Ž .

C 30 4319 2

7925 2

43 2

Ž

.

Ž .

C 31 4587 2

187 9

7901 2

59 2

Ž

.

Ž

We thank CONACYT Mexico and Consejo Supe-

rior de Investigaciones Cientıficas Spain for financial

support.

Ž

.

Ž .

Ž

.

Ž .

´

C 32 4778 2

1366 11

2849 11

7909 2

Ž .

76 3

Ž .

Ž

.

Ž .

.

C 33 4713 2

7932 2

81 3

Ž

.

Ž .

C 34 4443 2

3177 9

7954 2

75 3

Ž

.

Ž .

54 2

C 35 4245 2

Ž

2016 9

7946 2

.

Ž .

361 2

Rh 51 34044 1

Rh 52 41589 1

y40343 7

53685 1

55263 1

Ž .

351 2

y36927 6

References

Ž

.

Ž .

412 5

S 51

3941 1

y3744 2

5934 1

Ž

Ž .

376 5

S 52

3652 1

y2347 2

5137 1

w x

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.

Ž .

39 1

N 51 3582 1

y5733 6

5177 1

w x

Ž

.

2

Ž

.

Ž .

39 1

N 52 3897 1

y5672 6

5274 1

w x

3

Ž

.

Ž .

46 2

C 51 2879 1

y4245 9

5011 2

Ž

.

Ž

.

Ž .

C 52 3001 2

y5245 9

5341 2

47 2

w x

4

´ ´

Ž

.

Ž .

C 53 3164 2

y4331 10

5684 2

49 2

Ž

.

Ž .

C 54 3147 2

y2801 9

5576 2

45 2

Ž

.

Ž

.

Ž .

45 2

C 55 2960 2

y2720 9

5161 2

w x

5

Ž

.

Ž

.

Ž .

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C 56 2673 1

y4656 9

4578 2

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Ž

.

Ž .

81 3

C 57 2953 2

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5328 2

w x

6

Ž

.

Ž .

77 3

C 58 3312 2

y4915 8

6098 2

Ž

.

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Ž

.

Ž .

71 2

C 59 3269 1

y1444 8

5852 2

w x

7

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therein.

´

Ž

.

Ž .

C 60 2858 1

y1272 9

4922 2

72 2

Ž

.

Ž

.

Ž .

y3736 10

Ž .

C 61 4521 1

5367 2

50 2

w x

8

Ž

.

Ž .

C 62 4435 2

y2192 9

Ž .

5380 2

54 2

Ž

.

Ž

.

Ž .

50 2

C 63 4510 2

y1891 8

5765 2

(

)

J.J. Garcıa et al.rJournal of Organometallic Chemistry 551 1998 55–65

65

´

w x

w

x

9

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.

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x

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12 J.J. Garcıa, M.L. Hernandez, H. Torrens, A. Gutierrez, F. del

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.

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x

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x

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Article Doi

Binuclear pentamethylcyclopentadienyl rhodium(III) compounds with pyrazolate and thiolate bridging ligands

DOI: 10.1016/S0022-328X(97)00391-4

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Full text of DOI:10.1016/S0022-328X(97)00391-4

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