C-S, C-H, and N-H bond cleavage of heterocycles by a zero-valent iron complex, Fe(N2)(depe)2 [depe=1,2-bis(diethylphosphino)ethane]

www.elsevier.nl/locate/ica

Inorganica Chimica Acta 291 (1999) 341–354

C–S, C–H, and N–H bond cleavage of heterocycles by a

zero-valent iron complex, Fe(N₂)(depe)₂

[depe=1,2-bis(diethylphosphino)ethane]

Takashi Morikita ^a, Masafumi Hirano ^a, Akito Sasaki ^b, Sanshiro Komiya ^a,*

^aDepartment of Applied Chemistry, Faculty of Technology, Tokyo Uni6ersity of Agriculture and Technology, 2-24-16 Nakacho, Koganei,

Tokyo 184-8588, Japan

^bX-ray Research Laboratory, Rigaku Corporation, 3-9-12 Matsubara, Akishima, Tokyo 196-8666, Japan

Received 29 December 1998; accepted 15 March 1999

Abstract

Treatment of Fe(N₂)(depe)₂[depe=1,2-bis(diethylphosphino)ethane] (1) with benzo[b]thiophene at roo_¸m_¹t_¹em_¹¹pe_¹ra_ºture results in

¸¹¹¹¹¹¹¹º

the regioselective C–S and C–H bond cleavages giving Fe(SC₆H₄CHꢀCH)(depe)₂(2a) and trans-FeH(CꢀCHC₆H₄S)(depe)₂(3a)

in 72 and 19% yields, respectively. Complex 1 also reacts with thiophene, 2- and 3-acetylthiophenes and 2- and 3-methylthiophenes

¸¹¹¹¹¹¹¹¹¹º

to give both

_{¸¹¹¹¹¹¹¹}C_º–S and C–H_¸¹b_¹on_¹d_¹¹o_¹x_¹id_¹a_¹tiv_¹e_¹¹a_¹d_ºdition products: Fe(SCHꢀCHC_¸H_¹ꢀ_¹C_¹H_¹)(_¹de_¹p_¹e)_¹₂_¹¹(2_¹b_º) and trans-

FeH(CꢀCHCHꢀCHS)(depe)₂(3b), Fe[SC(COMe)ꢀCHCHꢀCH](depe)₂(2c) and trans-FeH[CꢀCHCHꢀC(COMe)S](depe)₂(3c),

¸¹¹¹¹¹¹¹¹¹¹¹º

¸¹¹¹¹¹¹¹¹¹º

¸¹¹¹¹¹¹¹¹¹¹¹º

Fe[SC(Me)ꢀCHCHꢀCH](depe)₂(2d) and trans-FeH[CꢀCHCHꢀC(Me)S](depe)₂(3d), and Fe[SCHꢀC(Me)CHꢀCH](depe)₂(2e) and

¸¹¹¹¹¹¹¹¹¹º

trans-FeH[CꢀCHC(Me)ꢀCHS](depe)₂(3e), respectively. On the other hand, only C–H bond cleavag_¸e _¹ta_¹k_¹es_¹p_¹la_¹c_¹e_ºin the reactions

of 1 with furans such as furan, benzo[b]furan, and 2,3-dihydrofuran to give trans-FeH(CꢀCHCHꢀCHO)(depe)₂(4a),

¸¹¹¹¹¹¹º

)

FeH(CꢀCHC₆H₄O)(depe)₂(4b) and trans-FeH(CꢀCHOCH₂CH₂)(depe)₂(4c) and N–H_¸b_¹o_¹nd_¹¹is_¹ex_¹c_¹lu_ºsively cleaved by the reaction

of 1 with_¸p_¹y_¹rr_¹o_¹le_ºs such as pyrrole, indole an_¸d_¹2_¹-a_¹c_¹et_¹yl_¹py_¹r_¹ro_¹le_¹¹to_ºgive trans-FeH(NCHꢀCHCHꢀCH)(depe)₂(5a), trans- and

cis-FeH(NCHꢀCHC₆H₄)(depe)₂(5b) and FeH[NC(COMe)ꢀCHCHꢀCH](h²-depe)(h¹-depe) (6). Treatment of 2a with MeI results

in the Fe–S bond cleavage of the thiaferracycle giving trans-FeI[(E)-CHꢀCHC₆H₄-2-SMe](depe)₂(7) whose structure is

unequivocally characterized by X-ray analysis. In contrast, hydrogenolysis of 2a with H₂(50 atm) leads to the cleavage of the

reserved.

Keywords: Crystal structures; Iron complexes; Diphosphine complexes; Sulfur ligand complexes; Activation of heterocycles

1. Introduction

with Fe complexes is still less explored, except for the

photochemical C–S and C–H bond activation of thio-

phene and methylthiophene by FeH₂(dmpe)₂[dmpe=

1,2-bis(dimethylphosphino)ethane] by Field and

co-workers [6]. We recently reported the isolation of a

dinitrogen complex of iron(0), Fe(N₂)(depe)₂[depe=

1,2-bis(diethylphosphino)ethane] (1), which showed a

variety of reactivities toward H₂, CO, CO₂, CS₂, C₂H₄,

2,6-xylyl isocyanide and styrenes accompanied by

smooth release of a dinitrogen molecule at room tem-

perature (r.t.) without irradiation of light [7,8]. Such

lability of 1 is considered to arise from the easy libera-

tion of the dinitrogen ligand. Herein we wish to report

the C–H and C–S bond activation of heterocyclic

Activation of heterocyclic compounds is an intrigu-

ing ﬁeld of organometallic chemistry because of its

potential applications in catalysis and organic synthesis.

Particularly, much attention has been focused on the

activation of thiophenes in the viewpoint of mecha-

nisms for catalytic hydrodesulfurization (HDS) [1–5].

Although many examples using Ni, Pt, Co, Rh, Ir, Ru

and Mo complexes have been reported as models for

HDS [1–5], such activation of heterocyclic compounds

* Corresponding author. Fax : +81-42-387 7500.

E-mail address: komiya@cc.tuat.ac.jp (S. Komiya)

PII: S0020-1693(99)00146-2

342

T. Morikita et al. / Inorganica Chimica Acta 291 (1999) 341–354

compounds such as thiophenes, furans, and pyrroles

with 1 without photo irradiation under ambient condi-

tions. Reactions of the resulting complexes are also

described.

2.1.1. C–S and C–H bond clea6age of thiophenes

The reaction of Fe(N₂)(depe)₂[depe=1,2-bis(di-

ethylphosphino)ethane] (1) with benzo[b]thiophene at

r.t. in THF resulted in the cleavage of both C–S and

¸¹¹¹¹¹¹¹º

C–H bonds_¸t_¹o_¹g_¹iv_¹e_¹F_ºe(SC₆H₄CHꢀCH)(depe)₂(2a) and

trans-FeH(CꢀCHC₆H₄S)(depe)₂(3a), respectively, in a

7:2 ratio (Table 1, entry 1). The former complex 2a was

isolated by the preferential crystallization from cold

pentane in 41% yield as analytically pure dark red

crystals. The molecular structure of 2a was determined

by NMR spectroscopy as well as by X-ray structure

analysis. The ³¹P{¹H} NMR spectrum of 2a showed an

AMNX pattern at l 55.1, 66.6, 69.5 and 76.5 indicating

cis conﬁguration of 2a. In the ¹H NMR spectrum of 2a,

the oleﬁnic protons are observed at l 7.91 (dd, J=11.7

2. Results and discussion

2.1. Reactions of heterocycles with Fe(N₂)(depe)₂

Reactions of various heterocycles such as thiophenes,

furans, and pyrroles with Fe(N₂)(depe)₂[depe=1,2-

bis(diethylphosphino)ethane] (1) were performed and

these results are summarized in Scheme 1 and Table 1.

Activation of heterocycles with 1 and characterization

of the products are discussed below.

Scheme 1.

T. Morikita et al. / Inorganica Chimica Acta 291 (1999) 341–354

343

Table 1

Summary of the reactions of 1 with ﬁve-membered heterocycles ^a

Entry

Heterocycles

Time (h)

Temp. (°C)

Product(s) (% yield)

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

Benzo[b]thiophene

Thiophene

168

48

r.t.

70

r.t.

50

2a (72)+3a (19)

2b (44)+3b (51)

2c (53)+3c (26)

2d (24)+3d (62)

2-Acetylthiophene

2-Methylthiophene

3-Methylthiophene

Dibenzothiophene

2,5-Dimethylthiophene

Tetrahydrothiophene

2-Methylbenzo[b]thiophene

2,3-Dihydrobenzo[b]thiophene

Furan

2e (16)+3e (70)

n.r. ^b

n.r.

4a (47)

4b (65)

4c (95)

n.r.

5a (95)

cis-5b (23)+trans-5b (12)

6 (95)

n.r.

Benzo[b]furan

2,3-Dihydrofuran

2-Acetylfuran

Dibenzofuran

2,5-Dimethylfuran

2,5-Dihydrofuran

Tetrahydrofuran

2,3-Dihydrobenzofuran

Pyrrole

r.t.

50

r.t.

50

Indole

2-Acetylpyrrole

N-Methylpyrrole

2,5-Dimethylpyrrole

Pyrrolidine

2-Methylindole

50

^aSolvent: C₆D₆.

^bn.r., no reaction.

1

iron(II) center. Consistently, in the H NMR spectrum,

a hydride signal is observed as a quintet at l −18.83

[J(H–P)=48.2 Hz] coupled to four magnetically equiv-

alent phosphorus atoms. The oleﬁnic proton of benzo-

and 6.3 Hz, 1H) and 8.27 (ddt, J=21.0, 11.7 and 3.1

Hz, 1H) coupled to each other [³J(H–H)=11.7 Hz]

and to phosphorus atoms [³J(H–P_trans)=21.0 Hz,

4

³J(H–P_cis)=3.1 Hz, and J(H–P_trans)=6.3 Hz]. These

facts suggest that the C–S bond between the oleﬁnic

carbon and the sulfur atoms has been cleaved via

oxidative addition.

The molecular structure of 2a was also determined by

the X-ray structure analysis. An ^ORTEPdrawing of 2a is

shown in Fig. 1 and selected bond distances and angles

are summarized in Table 2.

Complex 2a is best regarded as an octahedral thiafer-

racycle, which is formed by oxidative addition of the

C(1)–S(1) bond of benzo[b]thiophene to the iron(0).

This is consistent with the NMR data of 2a suggesting

that the molecular structure basically remained intact in

the solution state. Similar C–S oxidative addition prod-

ucts of benzo[b]thiophene such as I^¸r(^¹S^¹C^¹₆H^¹₄^¹C^¹H^¹ꢀ^ºCH)-

(_¸C_¹l)(_¹P_¹M_¹e_¹₃)_¹₄_¹º[9],

I^¸r(^¹S^¹C^¹₆H^¹₄^¹C^¹H^¹ꢀ^ºCH)(tdpme)

[2b],

¸¹¹¹¹¹¹¹¹º

Pt(SC₆H₄CHꢀCH)(PEt₃)₂[2c], and Rh(SC₆H₄CHꢀC-

Me)(Cp*)(PMe₃) [10] have also been reported recently.

The C–H oxidative addition product 3a was isolated

from the mother liquor after preferential crystallization

of 2a in the analytically pure form. The ³¹P{¹H} NMR

spectrum of 3a shows a singlet at l 92.8 suggesting two

depe ligands in an equatorial plane in the octahedral

¸¹¹¹¹¹¹¹º

Fig. 1. ORTEP drawing of Fe(SC₆H₄CHꢀCH)(depe)₂(2a). All hydro-

gen atoms are omitted for clarity. Atoms with an asterisk were

generated by the symmetrical operations. Ellipsoids represent 50%

probability.

344

T. Morikita et al. / Inorganica Chimica Acta 291 (1999) 341–354

¸¹¹¹¹¹¹¹º

(CꢀCHCHꢀCHS)(depe)₂(3b) (entry 2). In this reaction,

the C–H bond oxidative addition of thiophene can take

place at the 2- and 3-positions. It is known that trans-

RhCl(CO)(PMe₃)₂can react with both the 2- and 3-

Table 2

¸¹¹¹¹¹¹º

,

Selected bond angles (°) and lengths (A) of Fe(SC₆H₄CHꢀCH)(depe)₂

(2a)

Fe(1)–S(1)

Fe(1)–P(1)

C(1)–C(2)

C(3)–C(4)

C(4)–C(5)

C(6)–C(7)

C(7)–C(8)

2.207(2)

2.236(1)

1.42(1)

1.39(1)

1.34(2)

1.37(1)

1.24(3)

Fe(1)–C(1)

Fe(1)–P(2)

C(2)–C(3)

C(3)–C(8)

C(5)–C(6)

C(7)–C(8)

2.132(6)

2.233(1)

1.45(1)

1.38(1)

1.40(2)

1.42(1)

po_¸s_¹it_¹io_¹n_¹s _¹¹¹of_ºthiophene

to

give

RhHCl-

¸¹¹¹¹¹¹º

(CꢀCHCHꢀCHS)(PMe₃)₂and RhHCl(CꢀCHSCHꢀCH)-

(PMe₃)₂[11]. The thienyl group in 3b must bond to Fe

at the 2-position, because all signals assignable to the

thienyl protons show a linkage of coupling. The total

yields of 2b and 3b were 44 and 51%, respectively (entry

2).

The treatment of 1 with 2-acetylthiophene resulted

in the formation of a mixture of two iron species

(T_¸a_¹b_¹le_¹¹¹1,_¹¹e_¹n_¹tr_¹y_¹º3), from which trans-FeH-

[CꢀCHCHꢀC(COMe)S](depe)₂(3c) was isolated by re-

crystallization from hexane, and the other species is

C(1)–Fe(1)–S(1)

C(1)–Fe(1)–P(2)

C(1)–Fe(1)–P(2*)

S(1)–Fe(1)–P(2)

S(1)–Fe(1)–P(2*)

P(1)–Fe(1)–P(1*)

91.5(2)

82.7(2)

86.52(8)

86.91(8)

92.01(6)

C(1)–Fe(1)–P(1)

C(1)–Fe(1)–P(1*)

S(1)–Fe(1)–P(1)

166.8(2)

84.4(2)

93.69(6)

S(1)–Fe(1)–P(1*) 171.25(7)

P(1)–Fe(1)–P(2)

P(1)–Fe(1)–P(2*)

100.55(5)

85.52(5)

P(1*)–Fe(1)–P(2*) 100.55(5)

P(2)–Fe(1)–P(2*) 171.33(7)

assigned as the C–S bond oxidative addition product

¸¹¹¹¹¹¹¹¹¹¹¹¹¹º

thienyl ligand is observed as a singlet at l 6.83, and the

aromatic protons appear at l 6.95 (t), 7.20 (t), 7.64 (d),

and 7.81 (d). These data support the oxidative addition

of one of the oleﬁnic C–H bonds of benzo[b]thiophene.

Complexes 2a and 3a must be produced by indepen-

dent reactions of 1 with benzo[b]thiophene, because the

ratio of the isolated 2a and 3a remained intact even

after prolonged heating at 70°C for 48 h in benzene-d₆.

In addition, the isolated complexes 2a and 3a did not

isomerize under these conditions, suggesting that these

complexes are not in equilibrium. However, upon in-

creasing the [benzo[b]thiophene]:[1] ratio from 1:1 to

30:1, the ratio of 2a:3a increased from 70:30 to 85:15.

These results suggest that the C–S and C–H bond

cleavages took place via independent routes and the

C–S bond cleavage process is more effectively en-

hanced with increase in the benzo[b]thiophene concen-

tration. Such a concentration effect of benzo[b]-

thiophene would be most consistent with the associative

pathway for 2a but not for 3a. Consistently, no signiﬁ-

cant enhancement was observed for the formation of 2a

under vacuum excluding a dissociative mechanism. As

we reported previously [7a], complex 1 does not liberate

the dinitrogen ligand under high vacuum and

Perthuisot and Jones [8] proposed an associative mech-

anism for the displacement of the dinitrogen ligand in 1

by H₂, CO, ethylene, and 2,6-xylyl isocyanide by kinetic

studies. On the other hand, the rate determining step

for the formation of 3a would be independent of the

concentration of the benzo[b]thiophene, though a de-

tailed mechanism is not clear at present.

Fe[SC(COMe)ꢀCHCHꢀCH](depe)₂(2c). p-Electrons in

the thiaferracycle are considered to be delocalized be-

cause one of the protons appeared at extremely low

ﬁeld (l 8.98) which may be characteristic of the proton

of alkenyl a-carbon due to the ring current effect as

Bleeke et al. reported [12].

The reaction of 1 with 2-methylthiophene gave a

similar mixture of two species (Table 1, entry 4). One of

them is characterized as a C–S bond oxidative addition

¸¹¹¹¹¹¹¹¹¹¹¹º

product Fe[SC(Me)ꢀCHCHꢀCH](depe)₂(2d) by NMR

data (see Section 3). However, characterization of the

other species is worth noting. This other species shows

a singlet at l 93.6 in the ³¹P{¹H} NMR spectrum, and

signals at l −19.47, 2.59, 6.36 and 6.89 assignable to

1

the hydrido, methyl, and aromatic protons in the H

NMR spectrum, suggesting the formation of a hydri-

dothienyliron(II) complex. Unfortunately, the regio-

chemistry in the C–H bond oxidative addition of

2-methylthiophene is not clear at present, since broad-

ening of signals of the thienyl ring in the ¹H NMR

spectrum prevented the detail assignment of the

coupling.

We

believe

that

trans-FeH-

¸¹¹¹¹¹¹¹¹¹º

[CꢀCHCHꢀC(Me)S](depe)₂(3d) is the most appropriate

structure because of the following reasons: (i) both

thiophene and 2-acetylthiophene react with

1 at

the carbon adjacent to the sulfur atom to give 3b

and 3c; (ii) formation of Fe[SC(Me)ꢀCHCHꢀCH]-

(d_¸m_¹p_¹e_¹)₂_¹¹(_¹dm_¹¹pe_¹ºanalog of 2d) and trans-FeH-

[CꢀCHCHꢀC(Me)S](dmpe)₂(dmpe analog of 3d) is re-

ported in the reaction of 2-methylthiophene with

FeH₂(dmpe)₂[6].

Encouraged by the above results, reactions of

1 with various thiophene derivatives were carried

out (Scheme 1) and detail spectroscopic and physi-

cal data of these products are described in Section

3. Reaction of 1 with thiophene also gave a mixture of

t_¸he_¹¹C_¹–_¹S_¹a_¹n_¹d_¹C_¹–_ºH bond oxidative addition products

Fe(SCHꢀCHCHꢀCH)(depe)₂(2b) and trans-FeH-

Reaction of 1 with 3-methylthiophene also gave a

mixture of the C–H and C–S bond oxidative addition

products (Table 1, entry 5). The C–S bond oxidative

addition product shows an AMNX pattern at l 55.6,

65.8, 68.1 and 76.5 in the ³¹P{¹H} NMR spectrum, and

a singlet at l 2.11 due to the methyl group, two broad

peaks at l 5.68 and 7.29, and a broad multiplet at l

T. Morikita et al. / Inorganica Chimica Acta 291 (1999) 341–354

345

The ³¹P{¹H} NMR spectrum of 4a shows only one

resonance at l 96.6, which is assignable to four magnet-

ically equivalent phosphorus atoms in the octahedral

structure. The ¹H NMR spectrum of 4a shows a quintet

in high ﬁeld (l −18.15) assignable to the hydride

group and three broad signals assignable to the furyl

ligand in the aromatic region. Although furan can react

with 1 at either the 2- or 3-position of furan, detailed

characterization of 4a was unsuccessful because of sig-

niﬁcant broadening of the aromatic protons. The C–H

bond activation at the 2-position of furan was previ-

ously reported by Guerchais and co-workers [13], Sel-

nau and Merola [9] and Jones et al. [14], and no

examples have been reported for that at the 3-position

of furan to our knowledge. Thus, this product is likely

to_¸¹be_¹¹(_¹hy_¹d_¹ri_¹d_ºo)(2-furyl)iron(II) complex, trans-FeH-

(CꢀCHCHꢀCHO)(depe)₂(4a) (Table 1, entry 11).

Treatment of 1 with benzo[b]furan also gave only the

C_¸–H_¹¹¹b_¹on_¹d_ºoxidative addition product trans-FeH-

(CꢀCHC₆H₄O)(depe)₂(4b), which was characterized by

the analogy of the benzo[b]thiophene analog 3a (Table

1, entry 12).

8.02 coupled to the phosphorus atoms in the

¹H NMR spe_¸ct_¹ru_¹m_¹._{¹¹¹¹¹¹¹¹º}

Since two types of thia-

f_¸er_¹ra_¹c_¹yc_¹le_¹s_¹, _¹¹¹F_¹e[_¹S_ºCHꢀC(Me)CHꢀCH](depe)₂and

Fe[SCHꢀCHC(Me)ꢀCH](depe)₂are possible, 2-deu-

terio-3-methylthiophene (99% deuterized) was em-

ployed in this reaction to determine the regioselectivity.

The ¹H NMR spectrum of the thiaferracycle shows that

a singlet at l 2.11 due to the methyl group, and broad

peaks at l 7.29 and 8.02 due to the thienyl ring

protons. While a broad peak at l 5.68 disappeared, a

multiplet at l 8.02 coupled to phosphorus atoms re-

1

mained in the H NMR _¸sp_¹e_¹ct_¹ru_¹m_¹._¹T_¹h_¹e_¹se_¹r_¹es_ºults clearly

show the formation of Fe[SCHꢀC(Me)CHꢀCH](depe)₂

(2e) as the C–S bond oxidative addition product. On

the other hand, the C–H bond oxidative addition

product shows a singlet at l 93.4 in the ³¹P{¹H} NMR

spectrum. In the ¹H NMR spectrum, a quintet at l

−19.40 assignable to the hydride, a singlet at l 2.38

due to the methyl group, and signals at l 6.19 and 7.07

due to the thienyl ring protons are observed. When

2-deuterio-3-methylthiophene was employed in this re-

action, a signal at l 7.07 disappeared, but the signals at

l −19.40, 2.38 and 6.19 remained. Taking into ac-

count these results and by the analogies discussed

above, the C–H bond oxidat_¸iv_¹e_¹a_¹d_¹di_¹ti_¹on_¹¹p_¹ro_ºduct was

characterized as trans-FeH[CꢀCHC(Me)ꢀCHS](depe)₂

(3e).

It is worth noting that 2,3-dihydrofuran quantita-

tively _¸re_¹a_¹ct_¹e_¹d_¹w_¹it_ºh 1 at the 3-position to give trans-

FeH(CꢀCHOCH₂CH₂)(depe)₂(4c) (Table 1, entry 13).

The ³¹P{¹H} NMR spectrum of 4c shows a singlet at l

96.8 suggesting magnetically equivalent phosphorus

1

atoms. In the H NMR spectrum of 4c, a quintet at l

−17.85 assignable to the hydride group is observed.

Two triplets and one singlet are observed at l 2.64 (t,

J=8.3 Hz, 2H), 4.00 (s, 1H) and 4.02 (t, J=8.3 Hz,

2H), which are assigned to two types of aliphatic

protons coupled to each other and one isolated oleﬁnic

proton on the dihydrofuranyl ring. These coupling pat-

terns suggest the sp²C–H bond cleavage of 2,3-dihy-

drofuran at the 3-position. It is worthwhile noting that

the reaction of FeH₂(dmpe)₂with cyclopentene under

UV irradiation also resulted in the sp²C–H bond

As summarized in Table 1, it seems that an electron

withdrawing group in thiophene enhances the activa-

tion of the C–S bond over the C–H bond. Such a trend

is also reported for Rh complexes [2k]. It is also note-

worthy that the iron has regioselectively attacked the

less hindered C–S or C–H bond. These regioselectivi-

ties are in sharp contrast to the photochemical reac-

tions of cis-FeH₂(dmpe)₂with 3-methylthiophene which

gave a mixture of the regioisomers [6]. Dibenzothio-

phene, 2,5-dimethylthiophene, and 2-methylbenzo[b]-

thiophene did not react (Table 1, entries 6, 7 and 9).

This is most likely due to the steric congestion around

the sulfur atom, suggesting the importance of pre-coor-

dination of the sulfur atom may be important for these

bond cleavage reactions. It is interesting that both

tetrahydrothiophene and 2,3-dihydrobenzo[b]thiophene

also did not react on treatment with 1 even at 70°C.

oxidative addition

_{¸¹¹¹¹¹¹¹¹º}to the iron center to give

FeH(CꢀCHCH₂CH₂CH₂)(dmpe)₂exclusively [15].

On the other hand, 2-acetylfuran, dibenzofuran, 2,5-

dimethylfuran, 2,5-dihydrofuran, tetrahydrofuran and

2,3-dihydrobenzo[b]furan remained unreacted (Table 1,

entries 14–19) even at 50°C.

2.1.3. N–H bond clea6age of pyrroles

Complex 1 reacted with pyrroles such as pyrrole, and

2.1.2. C–H bond clea6age of furans

indole in C₆D₆at r.t. to give (hydrido)(N-pyrrolyl)-

¸¹¹¹¹¹¹¹º

Contrary to the reactions of thiophenes, reactions of

1 with furans such as furan, benzo[b]furan, and

2,3-dihydrofuran exclusively lead to oxidative addi-

iron(II) complexes trans-FeH(NCHꢀCHCHꢀCH)-

¸¹¹¹¹º

(depe)₂(5a) and cis- and trans-FeH(NCHꢀCHC₆H₄)-

(depe)₂(5b) as shown in Scheme 1 (Table 1, entries 20

and 21).

tion of the C–H bond to give (hydrido)(furyl)iron

¸¹¹¹¹¹¹¹º

A singlet at l 91.8 in the ³¹P{¹H} NMR spectrum

and a quintet at l −27.94 indicating a hydride suggest

a trans structure of 5a. The pyrrolyl protons appear as

two broad signals with equal intensity (2H each) in the

(II) complexes trans-FeH(CꢀCHCHꢀCHO)(depe)₂

¸¹¹¹¹¹º

(4a), trans-FeH(CꢀCHC₆H₄O)(depe)₂(4b) and trans-

¸¹¹¹¹¹¹º

FeH(CꢀCHOCH₂CH₂)(depe)₂(4c), respectively (Scheme

1).

346

T. Morikita et al. / Inorganica Chimica Acta 291 (1999) 341–354

Reaction of 1 with indole also led to the oxida-

tive addition of the N–H bond to give 5b. In these

reactions, only the N–H bond oxidatively adds to

the iron(0) to give 5 and neither the C–N nor C–H

bond is cleaved under these conditions. Speciﬁc activa-

tion of the N–H bond in pyrroles may be due to the

high acidity of the N–H proton in pyrroles. Among

these complexes, it is interesting to note the structural

fe_¸at_¹u_¹re_¹¹o_¹f_¹¹hy_¹d_¹r_¹id_¹o(_ºpyrrolyl)iron(II) complex FeH-

[NC(COMe)ꢀCHCHꢀCH](h²-depe)(h¹-depe) (6) deri-

ved from 2-acetylpyrrole (Table 1, entry 22). The

³¹P{¹H} NMR spectrum of 6 shows four magnetically

inequivalent phosphorus atoms at l −18.2 (d, J=21.8

Hz, 1P), 48.9 (ddd, J=125.2, 37.1, 21.8 Hz, 1P), 95.6

(dd, J=125.2, 37.1 Hz, 1P) and 98.7 (t, J=37.1 Hz,

1P). Observation of a large coupling constant (J=

125.2 Hz) between the above two P ligands suggests the

trans conﬁguration of these P atoms. The signal at l

−18.2 is assignable to the uncoordinated P atom in

depe ligands providing a monodentate depe ligand.

Consistently with this fact, the hydride signal appears

as a doublet of doublets of doublets at l −26.18

¸¹¹¹¹¹¹º

Fig. 2. ^ORTEPdrawing of FeH(NCHꢀCHCHꢀCH)(depe)₂(5a). All

hydrogen atoms are omitted for clarity. Ellipsoids represent 50%

probability.

1

(J=63.3, 52.8, 47.9 Hz, 1H) in the H NMR spectrum

of 6, which is coupled to only three inequivalent phos-

phorus atoms. A possible O,N-bidentate coordination

of the 2-acetylpyrrolyl ligand giving a stable 18 electron

complex is excluded, since the IR spectrum of 6 shows

a w(CꢀO) band at 1652 cm⁻¹the value of which is

almost the same as that of free 2-acetylpyrrole

[w(CꢀO)=1646 cm⁻¹]. Thus, 6 may have a tbp struc-

ture where both the hydrido and 2-acetylpyrrolyl lig-

ands occupy the equatorial sites. Probably, steric

congestion around the iron center may force such a

partial dissociation of the P ligand.

aromatic region at l 6.21 and 6.58. The molecular

structure of 5a was unambiguously determined by X-

ray structure analysis. An ^ORTEPdrawing of 5a is

shown in Fig. 2 and selected bond distances and angles

are summarized in Table 3.

The geometry of 5a is also regarded as an octahedron

where the pyrrolyl and the hydrido ligands are located

in trans positions. The bond distances between N(1)–

C(21), C(21)–C(22), C(22)–C(23), C(23)–C(24) and

Complex 1 did not react with N-methylpyrrole, 2,5-

dimethylpyrrole, pyrrolidine and 2-methylindol (Table

1, entries 22–26).

,

C(24)–N(1) are in the range of 1.360–1.383 A, showing

extensive electron delocalization in the pyrrolyl ligand.

Table 3

2.2. Reactions of the thiaferracycle complex 2a

,

Selected bond angles (°) and lengths (A) of trans-FeH

¸¹¹¹¹¹¹¹º

(NCHꢀCHCHꢀCH)(depe)₂(5a)

It is important to describe the chemical reactivity of

thiaferracycle complexes, since they are regarded as one

of the possible intermediates in the HDS process, as

well as in the chemical transformation of heterocyclic

compounds.

The thiaferracycle complex 2a is reformed to benzo-

[b]thiophene in 58% yield by heating at 170°C in the

solid state under argon (Scheme 2).

Such reductive elimination of the C–S bond is en-

hanced by exposure of 2a with CO at 50°C to give

benzo[b]thiophene in 94% yield producing Fe(CO)-

(depe)₂(w(CꢀO)=1800 cm⁻¹) [7a,c,8,16]. Protono-

lysis of 2a by an excess amount of HCl gas in THF

or C₆D₆gave 2,3-dihydrobenzo[b]thiophene in 53%

yield with liberation of benzo[b]thiophene in 10%

yield. It is likely that 2,3-dihydrobenzo[b]thiophene was

Fe(1)–N(1)

Fe(1)–P(12)

Fe(1)–P(22)

N(1)–C(21)

C(21)–C(22)

C(23)–C(24)

2.092(3)

2.220(1)

2.209(1)

1.366(5)

1.368(6)

1.372(6)

Fe(1)–P(11)

Fe(1)–P(21)

Fe(1)–H(53)

N(1)–C(24)

C(22)–C(23)

2.209(1)

2.211(1)

1.29(4)

1.360(5)

1.383(7)

P(11)–Fe(1)–P(12)

P(11)–Fe(1)–P(22)

85.25(4)

93.48(4)

P(11)–Fe(1)–P(21) 177.25(5)

P(12)–Fe(1)–P(21)

P(21)–Fe(1)–P(22)

P(11)–Fe(1)–H(53)

P(21)–Fe(1)–H(53)

P(11)–Fe(1)–N(1)

P(21)–Fe(1)–N(1)

94.90(5)

85.67(5)

86(1)

90(1)

91.00(9)

91.70(9)

P(12)–Fe(1)–P(22) 165.04(5)

N(1)–Fe(1)–H(53)

P(12)–Fe(1)–H(53)

P(22)–Fe(1)–H53)

P(12)–Fe(1)–N(1)

P(22)–Fe(1)–N(1)

176(1)

84(1)

80(1)

97.4(1)

97.5(1)

N(1)–C(21)–C(22) 111.5(4)

C(22)–C(23)–C(24) 150.2(4)

C(21)–C(22)–C(23) 107.0(4)

C(21)–N(1)–C(24) 103.6(3)

T. Morikita et al. / Inorganica Chimica Acta 291 (1999) 341–354

347

Scheme 2.

the structure of 7 is likely to be trans-FeI[(E)-

CHꢀCHC₆H₄-2-SMe](depe)₂.

The X-ray structure analysis of 7 unequivocally indi-

cated a trans structure. The ORTEP drawing is depicted

in Fig. 3, and bond distances and angles are summa-

rized in Table 4.

This molecular structure is consistent with that de-

duced by NMR spectra and demonstrates that elec-

trophilic attack of MeI took place at the S atom,

followed by Fe–S bond cleavage and rotation of the

CꢀC double bond giving a trans conﬁguration of the

styryl moiety. Probably, the contribution of carbene

character in 7 facilitates the rotation of the CꢀC double

bond. Although the bond distance between Fe and C(1)

formed via 2-vinylbenzene-thiol [17] followed by the

cyclization¹.

The reaction of 2a with 10-fold amounts of MeI

immediately gave trans-FeI[(E)-CHꢀCHC₆H₄-2-SMe]-

(depe)₂(7) in 52% yield. The ³¹P{¹H} NMR spectrum

of 7 shows a singlet at l 70.2, suggesting four equiva-

1

lent phosphorus atoms. In the H NMR spectrum of 7,

a singlet at l 2.05 (3H), a doublet at l 6.43 (J=16.5

Hz, 1H) and a doublet of quintets at l 8.06 (J=16.5,

6.7 Hz, 1H) were observed. The singlet at l 2.05 is

assigned to the SMe group, and the signals at l 6.43

and 8.06 are assignable to the oleﬁnic protons, where

the large coupling constant (J=16.5 Hz) indicates that

those protons are mutually trans. The latter oleﬁnic

proton (l 8.06) also involves further coupling to four

equivalent phosphorus atoms (J=6.7 Hz). Therefore,

,

(2.00(2) A) is typical of a single bond, C(1) resonates at

l 179.7 in the ¹³C{¹H} NMR spectrum, supporting a

small contribution of its carbene character.

On the other hand, reaction of the thiaferracycle

complex with molecular hydrogen is interesting from

the mechanistic point of view of hydrodesulfurization.

Treatment of 2a with 50 atm of hydrogen at r.t. pro-

duces a mixture of cis- and trans-FeH(SC₆H₄-2-Et)-

¹The protonolysis of 2a with an excess amount of HCl gave

paramagnetic iron species which is tentatively assigned as

FeCl₂(depe)₂, because the ³¹P{¹H} NMR spectrum gave a broad peak

at l 75 in C₆D₆, which is identical with that of authentic FeCl₂(depe)₂

(l 75 (br) in C₆D₆at r.t.) (see Ref. [7a]).

348

T. Morikita et al. / Inorganica Chimica Acta 291 (1999) 341–354

protons. Therefore, the major species was characterized

as cis-FeH(SC₆H₄-2-Et)(depe)₂(8). On the other hand,

the minor isomer shows a singlet at l 88.8 in the

³¹P{¹H} NMR spectrum, and a quintet at l −26.97 in

the ¹H NMR spectrum is assignable to the hydrido

ligand. This suggests that the species is a hydridoiron

complex with four equivalent phosphorus atoms. The

¹H–¹H COSY spectrum suggests that the minor species

also has a 2-ethylbenzenethiolato ligand. According to

these spectroscopic data, the minor species was charac-

terized as trans-FeH(SC₆H₄-2-Et)(depe)₂(8). Acidolysis

of the mixture by excess hydrogen chloride in Et₂O led

to the formation of 2-ethylthiophenol in 20% yield

(Scheme 2).

In summary, a zerovalent iron complex, Fe(N₂)-

(depe)₂(1) can activate both C–S and C–H bonds of

thiophenes, the C–H bond of furans, and the N–H

bond of pyrroles without irradiation by light under

ambient c_¸on_¹d_¹it_¹io_¹n_¹s._¹I_¹t_ºis interesting to note that treat-

ment of Fe(SC₆H₄CHꢀCH)(depe)₂(2a) with MeI gave

trans-FeI[(E)-CHꢀCHC₆H₄-2-SMe](depe)₂(7) where

the methyl nucleophile attacked the S atom in 2a, while

that with molecular hydrogen gave cis- and trans-

FeH(SC₆H₄-2-Et)(depe)₂(8) where the molecular hy-

drogen attacked the carbon atoms in 2a.

Fig. 3. ^ORTEPdrawing of trans-FeI[(E)-CHꢀCHC₆H₄-2-SMe](depe)₂

(7). All hydrogen atoms are omitted for clarity. Ellipsoids represent

50% probability.

(depe)₂(8) in 52 and 21% yields, respectively (Scheme

2). The ³¹P{¹H} NMR spectrum of the major isomer

was observed as an AMNX pattern at l 63.5, 81.4, 85.9

and 91.1 indicating four inequivalent phosphorus

3. Experimental

3.1. General

1

atoms. In the H NMR spectrum of the major isomer,

All manipulations were carried out using standard

Schlenk and vacuum-line techniques. Fe(N₂)(depe)₂(1)

was prepared by the published procedure [7]. All sub-

strates were purchased and puriﬁed by distillation or

recrystallization. 2-Deuterio-3-methylthiophene was

prepared by the treatment of 2-bromo-3-methylthio-

phene with magnesium followed by hydrolysis with

D₂O and then by distillation. The content of deuterium

a doublet of triplets of doublets assignable to the

hydride ligand was observed at l −10.48 (J=69.9,

52.2, 30.2 Hz, 1H), where two of four phosphorus

atoms accidentally have a similar coupling constant.

1

The H–¹H COSY spectrum of 8 suggests that a quar-

tet observed at l 3.38 is assignable to the methylene

protons of the 2-ethylbenzenethiolato group, although

the corresponding methyl group overlapped with depe

1

was determined to be 98% by H NMR data. NMR

spectra were obtained from a Jeol LA-300 (300.4 MHz

Table 4

1

for H, 75.4 MHz for ¹³C, 121.6 MHz for ³¹P) spec-

,

Selected bond angles (°) and lengths (A) for trans-FeI[(E)-

CHꢀCHC₆H₄-2-SMe](depe)₂(7)

trometer using C₆D₆, CDCl₃, CD₂Cl₂, or toluene-d₈as

a solvent. The chemical shifts were reported in ppm

from internal TMS both in ¹H and ¹³C{¹H} NMR

spectra. Chemical shifts in ³¹P{¹H} NMR spectra were

reported in ppm downﬁeld from 85% H₃PO₄in D₂O as

an external standard. IR spectra were recorded on a

Jasco FT-IR-5M or Jasco FT-IR-410 spectrometer us-

ing KBr disks. The elemental analyses were performed

with a Perkin–Elmer 2400 Series II CHNS analyzer.

GLC analyses were performed with Shimadzu GC-

8APF, GC-14B gas liquid phase chromatographs using

glass-packed Porapack-Q, capillary TC-wax and HR-1

columns. Melting points were estimated under nitrogen

atmosphere with Yazawa capillary melting point ap-

paratus and the values were uncorrected.

Fe(1)–I(1)

Fe(1)–P(2)

Fe(1)–P(4)

S(1)–C(4)

C(1)–C(2)

C(3)–C(4)

C(4)–C(5)

C(6)–C(7)

2.774(4)

2.260(9)

2.255(8)

1.76(3)

1.25(3)

1.42(3)

1.39(4)

1.37(5)

Fe(1)–P(1)

Fe(1)–P(3)

Fe(1)–C(1)

S(1)–C(9)

C(2)–C(3)

C(3)–C(8)

C(5)–C(6)

C(7)–C(8)

2.270(8)

2.268(9)

2.00(2)

1.78(3)

1.45(3)

1.32(3)

1.30(4)

1.42(4)

I(1)–Fe(1)–C(1)

I(1)–Fe(1)–P(2)

I(1)–Fe(1)–P(4)

C(1)–Fe(1)–P(2)

C(1)–Fe(1)–P(4)

C(1)–C(2)–C(3)

176.4(8)

89.3(3)

91.6(3)

88.6(9)

90.5(9)

131(3)

I(1)–Fe(1)–P(1)

I(1)–Fe(1)–P(3)

C(1)–Fe(1)–P(1)

C(1)–Fe(1)–P(3)

Fe(1)–C(1)–C(2)

C(4)–S(1)–C(9)

89.3(3)

91.4(3)

87.6(8)

91.6(8)

140(2)

102(2)

T. Morikita et al. / Inorganica Chimica Acta 291 (1999) 341–354

349

¸¹¹¹¹¹¹¹¹¹º

3.2. Reaction of 1 with benzo[b]thiophene

Fe(SCHꢀCHCHꢀCH)(depe)₂(2b): Yield 44%; ¹H

NMR (C₆D₆): l 0.7–2.0 (m, 42H, depe), 2.1–2.5

(m, 2H, depe), 2.7–2.9 (m, 2H, depe), 2.9–3.1 (m,

2_¸H_¹, _¹¹d_¹ep_¹e_¹),_¹º6.01 (dd, J=9.2, 3.3 Hz, 1H,

A THF solution (12 ml) of benzo[b]thiophene (109.1

mg, 0.81 mmol) was introduced to a THF solution (3

ml) of 1 (403.5 mg, 0.81 mmol), and stirred at r.t. for 7

days. The color of the solution changed from light

orange solution to dark red. After removal of THF in

v_¸ac_¹u_¹o_¹, _¹¹th_¹e_¹ºresidue was extracted with hexane.

Fe(SC₆H₄CHꢀCH)(depe)₂(2a) was obtained by the

crystallization from hexane at −30°C as dark red

crystals in 41% isolated yield (200.2 mg, 0.33 mmol).

From _¸t_¹he_¹¹m_¹o_¹th_ºer liquor, a small amount of trans-

FeH(CꢀCHC₆H₄S)(depe)₂(3a) was obtained. These

chemical yields of 2a and 3a were calculated as 72 and

19%, respectively, by the ³¹P{¹H} NMR spectrum with

FeSCHCHCHCH), 6.46 (dd, J=9.2, 6.5 Hz, 1H,

¸¹¹¹¹¹¹¹º

FeSCHCHCHCH), 7.43 (dt, J=11.1, 6.3 Hz, 1H

¸¹¹¹¹¹¹¹º

FeSCHCHCHCH), 7.84 (dd, J=21.0, 11.1 Hz, 1H,

¸¹¹¹¹¹¹¹º

FeSCHCHCHCH); ³¹P{¹H} NMR (C₆D₆): l 55.5 (ddd,

J=24.6, 20.1, 7.3 Hz, 1P), 67.0 (ddd, J=243.1, 34.5,

24.6 Hz, 1P), 69.5 (ddd, J=243.1, 34.5, 20.1 Hz, 1P),

76.0 (td, J=34.5, 7.3 Hz); Anal. Found: C, 52.31; H,

9.98; S, 8.07. Calc. for C₂₄H₅₂FeP₄S: C, 52.18; H, 9.49;

S, 5.80%.

¸¹¹¹¹¹¹¹º

trans-FeH(CꢀCHCHꢀCHS)(depe)₂(3b): Yield 51%;

¹H NMR (C₆D₆): l −19.41 (qui, J=48.4 Hz, 1H,

Fe–H), 0.97 (br, 24H, PCH₂CH₃), 1.0–1.5 (m, 12H,

PCH₂CH₃, PCH₂CH₂P), 1.73 (m, 4H, PCH₂CH₃), 1.90

(br, 4H, PCH₂CH₂P), 2.13 (sext, J=7.3 Hz, 4H,

PCH₂CH₃), 6.58 (br d, J=1.8 Hz, 1H, aromatic-H),

7.26 (dd, J=5.4, 1.8 Hz, 1H, aromatic-H), 7.54 (d,

J=5.4 Hz, 1H, aromatic-H); ³¹P{¹H} NMR (C₆D₆): l

93._¸2 _¹(s_¹)._{¹¹¹¹¹¹¹¹¹¹¹º}

Fe[SC(COMe)ꢀCHCHꢀCH](depe)₂(2c): Yield 53%;

¹H NMR (C₆D₆): l 0.9–2.5 (m, 48H, depe), 2.73 (s,

3H, COCH₃), 7.44 (br, 1H, thiaferracyclic-H), 7.76 (br,

1H, thiaferracyclic-H), 8.98 (br, 1H, thiaferracyclic-H);

³¹P{¹H} NMR (C₆D₆): l 53.2 (td, J=21.9, 7.3 Hz, 1P),

65.0 (dt, J=238.2, 21.9 Hz, 1P), 68.3 (ddd, J=238.2,

34.6, 21.9 Hz, 1P), 74.8 (ddd, J=34.6, 21.9, 7.3 Hz,

PPh₃in a capillary tube as standard.

¸¹¹¹¹¹¹¹º

1

Fe(SC₆H₄CHꢀCH)(depe)₂(2a): Yield 72%; H NMR

(C₆D₆): l 0.6–2.7 (m, 48H, depe), 6.89 (t, J=7.5 Hz,

1H, aromatic-H), 6.96 (t, J=7.5 Hz, 1H, aromatic-H),

7.12 (d, J=7.5 Hz, 1H, aromatic-H), 7.91 (dd, J=

11.7, 6.3 Hz, 1H, oleﬁnic-H, partially overlapped with

the peak at l 7.94), 7.94 (d, J=7.5 Hz, 1H, aromatic-

H), 8.27 (ddt, J=21.0, 11.7, 3.1 Hz, oleﬁnic-H);

³¹P{¹H} NMR (C₆D₆): l 55.1 (ddd, J=26.6, 20.6, 7.3

Hz, 1P), 66.6 (ddd, J=207.6, 34.5, 26.6 Hz, 1P), 69.5

(ddd, J=207.6, 34.5, 20.6 Hz, 1P), 76.5 (td, J=34.5,

7.3 Hz, 1P); ¹³C{¹H} NMR (C₆D₆): l 9.0–25.7 (depe),

120.6 (s), 122.7 (s), 130.5 (s), 133.4 (s), 138.7 (s), 140.2

(s), 140.6 (s), 166.7 (m); Anal. Found: C, 55.36; H, 9.24;

S, 5.60. Calc. for C₂₈H₅₄FeP₄S: C, 55.82; H, 9.03; S,

1P).

¸¹¹¹¹¹¹¹¹¹¹¹º

5.32%; m.p. 123–125°C (dec.).

trans-FeH(CꢀCHC₆H₄S)(depe)₂(3a): Yield 19%; H

trans-FeH[CꢀCHCHꢀC(COMe)S](depe)₂(3c): Yield

¸¹¹¹¹¹º

1

26%; H NMR (C₆D₆): l −18.33 (qui, J=47.6 Hz,

NMR (C₆D₆): l −18.83 (qui, J=48.2 Hz, 1H, Fe–H),

0.92 (br, 24H, PCH₂CH₃), 1.08 (sext, J=7.1 Hz, 4H,

PCH₂CH₃), 1.35 (sext, J=7.4 Hz, 4H, PCH₂CH₃), 1.41

(br, 4H, PCH₂CH₂P), 1.69 (sext, J=7.1 Hz, 4H,

PCH₂CH₃), 1.93 (br, 4H, PCH₂CH₂P), 2.16 (sext, J=

7.4 Hz, 4H, PCH₂CH₃), 6.83 (s, 1H, oleﬁnic-H), 6.95 (t,

J=7.7 Hz, 1H, aromatic-H), 7.20 (t, J=7.7 Hz, 1H,

aromatic-H), 7.64 (d, J=7.7 Hz, 1H, aromatic-H), 7.81

(d, J=7.7 Hz, 1H, aromatic-H); ³¹P{¹H} NMR

(C₆D₆):l 92.8 (s). ¹³C{¹H} NMR (C₆D₆): l 9.4–26.3

(depe), 117.8 (s), 118.3 (s), 119.4 (s), 122.4 (s), 133.8 (s),

144.4 (s), 147.2 (s), 187.1 (qui, J=17.9 Hz); Anal.

Found: C, 55.38; H, 9.78; S, 5.99. Calc. for

C₂₈H₅₄FeP₄S: C, 55.82; H, 9.03; S, 5.32%.

1H, Fe–H), 0.89 (br, PCH₂CH₃, 24H), 1.02 (sext,

J=7.5 Hz, 4H, PCH₂CH₃, partially overlapped with

the peak at l 0.89), 1.27 (sext, J=7.5 Hz, 4H,

PCH₂CH₃, partially overlapped with the peak at l

1.31), 1.31 (br, 4H, PCH₂CH₂P, partially overlapped

with the peak at l 1.27), 1.63 (br sext, J=7.5 Hz,

PCH₂CH₃, 4H), 1.79 (br, 4H, PCH₂CH₂P), 1.99 (sext,

J=7.5 Hz, 4H, PCH₂CH₃), 2.36 (s, 3H, COCH₃), 6.61

(d, J=3.6 Hz, 1H, thienyl ring-H), 7.50 (d, J=3.6 Hz,

1H_¸, _¹th_¹ie_¹n_¹yl_¹r_¹in_¹g_¹-H_¹)_¹;_¹³¹_ºP{¹H} NMR (C₆D₆): l 91.9 (s).

1

Fe[SC(Me)ꢀCHCHꢀCH](depe)₂(2d): Yield 24%; H

NMR (C₆D₆): l 0.4–2.2 (m, 48H, depe), 2.38 (s, 3H,

CH₃), 7.2 (overlapped with the peak of C₆D₅H), 7.41

(br, 1H, thiaferracyclic-H), 7.65 (dd, J=18.2, 11.0 Hz,

1H, thiaferracyclic-H); ³¹P{¹H} NMR (C₆D₆): l 55.2

(td, J=25.0, 6.1 Hz, 1P), 66.0 (ddd, J=241.8, 34.2,

25.0 Hz, 1P), 68.9 (ddd, J=241.8, 34.2, 25.0 Hz, 1P),

3.3. Reaction of 1 with other thiophenes

Reaction of 1 with thiophene, 2-methylethiophene,

3-methylthiophene, and 2-acetylthiophene was per-

formed by the similar method of the reaction with

benzo[b]thiophene as described above. Yields were cal-

culated on the basis of their NMR spectra. ¹H and

³¹P{¹H} NMR spectral data of the products 2b–e and

3b–e are described as follows:

76.4 (td, J=34.2, 6.1 Hz, 1P).

¸¹¹¹¹¹¹¹¹¹º

trans-FeH[CꢀCHCHꢀC(Me)S](depe)₂(3d): Yield

1

62%; H NMR (C₆D₆): l −19.47 (qui, J=47.4 Hz,

1H, Fe–H), 0.98 (br, 24H, PCH₂CH₃), 1.0–1.5 (m,

12H, PCH₂CH₃, PCH₂CH₂P), 1.73 (br, 4H, PCH₂CH₃),

1.91 (br, 4H, PCH₂CH₂P), 2.18 (sext, J=7.2, 4H,

PCH₂CH₃), 2.59 (s, 3H, CH₃), 6.36 (br, 1H, aromatic-

350

T. Morikita et al. / Inorganica Chimica Acta 291 (1999) 341–354

H), 6.89 (br, 1H, aromatic-H); ³¹P{¹H} NMR (C₆D₆): l

ever, 2-acetylfuran, dibenzofuran, 2,5-dimethylfuran,

2,5-dihydrofuran, tetrahydrofuran, and 2,3-dihydroben-

zofuran are remained unreacted. These products 4b and

4c were characterized by ¹H and ³¹P{¹H} NMR spectra.

Yields were c_¸al_¹cu_¹la_¹t_¹ed_¹¹fr_ºom ³¹P{¹H} NMR spectra.

93._¸6 _¹(s_¹)._{¹¹¹¹¹¹¹¹¹º}

Fe[SCHꢀC(Me)CHꢀCH](depe)₂(2e): Yield 16%; H

1

NMR (C₆D₆): l 0.8–2.5 (m, 48H, depe), 2.11 (s, 3H,

CH₃), 5.68 (br, 1H, thiaferracyclic-H), 7.29 (br, 1H,

thiaferracyclic-H), 8.02 (br, 1H, thiaferracyclic-H);

³¹P{¹H} NMR (C₆D₆): l 55.6 (td, J=22.8, 7.3 Hz, 1P),

65.8 (ddd, J=249.2, 33.6, 22.8 Hz, 1P), 68.1 (ddd,

J=249.2, 33.6, 22.8 Hz, 1P), 76.5 (td, J=33.6, 7.3 Hz,

1

trans-FeH(CꢀCHC₆H₄O)(depe)₂(4b): Yield 65%. H

NMR (C₆D₆): l −17.41 (qui, J=45.7 Hz, 1H, Fe–H),

0.89 (br, 12H, PCH₂CH₃), 0.98 (br, 12H, PCH₂CH₃),

1.00 (m, 4H, PCH₂CH₃, overlapped with the peak at l

0.98), 1.18 (m, 4H, PCH₂CH₃), 1.42 (br, 8H,

PCH₂CH₂P, PCH₂CH₃), 1.72 (br, 4H, PCH₂CH₂P),

1.87 (m, 4H, PCH₂CH₃), 6.11 (s, 1H, oleinic-H), 6.94 (t,

J=7.5 Hz, 1H, aromatic-H), 7.1 (1H, overlapped with

the peak of C₆D₅H), 7.31 (d, J=7.5 Hz, 1H, aromatic-

H), 7.41 (d, J=7.5 Hz, 1H, aromatic-H); ³¹P{¹H}

NMR (C₆D₆):_¸l_¹¹95_¹.9_¹¹(s_¹)._º

1P).

¸¹¹¹¹¹¹¹¹¹º

trans-FeH[CꢀCHC(Me)ꢀCHS](depe)₂(3e): Yield

1

70%; H NMR (C₆D₆): l −19.40 (qui, J=47.9 Hz,

1H, Fe–H), 1.00 (br, 24H, PCH₂CH₃), 1.1–1.5 (m,

12H, PCH₂CH₃, PCH₂CH₂P), 1.75 (br, 4H, PCH₂CH₃),

1.93 (br, 4H, PCH₂CH₂P), 2.18 (sext, J=7.3 Hz, 4H,

PCH₂CH₃), 2.38 (s, 3H, CH₃), 6.19 (s, 1H, thienyl

ring-H), 7.07 (s, 1H, thienyl ring-H); ³¹P{¹H} NMR

(C₆_¸D_¹₆)_¹:_¹l_¹9_¹3_¹.4_¹(_¹s)_¹. _¹¹º

Fe[SCDꢀC(Me)CHꢀCH](depe)₂(2e-d₁): Yield 18%;

¹H NMR (C₆D₆): l 0.9–2.2 (m, 24H, depe), 2.13 (s,

3H, CH₃), 7.3 (br, 1H, thienyl ring-H, partially over-

lapped with the peak of C₆D₅H), 8.0 (br, 1H, thienyl

ring-H); ³¹P{¹H} NMR (C₆D₆): l 55.6 (td, J=23.1, 7.3

Hz, 1P), 65.8 (ddd, J=245.5, 35.2 Hz, 1P), 68.1 (ddd,

J=245.5, 35.2, 23.1 Hz, 1P), 76.5 (td, J=35.2, 7.3 Hz,

trans-FeH(CꢀCHOCH₂CH₂)(depe)₂(4c): Yield 95%.

¹H NMR (C₆D₆): l −17.85 (qui, J=45.0 Hz, 1H,

Fe–H), 1.04 (br, 12H, PCH₂CH₃), 1.08 (br, 12H,

PCH₂CH₃), 1.24 (sext, J=7.5 Hz, 4H, PCH₂CH₃), 1.37

(br, 4H, PCH₂CH₂P), 1.50 (sext, J=7.2 Hz, 4H,

PCH₂CH₃), 1.78 (br, 8H, PCH₂CH₃, PCH₂CH₂P), 2.38

(sext, J=7.2 Hz, 4H, PCH₂CH₃), 2.64 (t, J=8.3 Hz,

2H, aliphatic-H), 4.00 (s, 1H, oleﬁnic-H), 4.02 (t, J=

8.3 Hz, 2H, aliphatic-H); ³¹P{¹H} NMR (C₆D₆): l 96.8

(s).

1P).

¸¹¹¹¹¹¹¹¹¹º

trans-FeH[CꢀCHC(Me)ꢀCDS](depe)₂(3e-d₁): Yield

3.5. Reaction of 1 with pyrrole

1

50%; H NMR (C₆D₆): l −19.40 (qui, J=47.9 Hz,

1H, Fe–H), 0.98 (br, 24H, PCH₂CH₃), 1.1–1.5 (m,

12H, PCH₂CH₃, PCH₂CH₂P), 1.72 (br, 4H, PCH₂CH₃),

1.92 (br, 4H, PCH₂CH₂P), 2.18 (br, 4H, PCH₂CH₃),

2.39 (s, 3H, CH₃), 6.21 (s, 1H, thienyl ring-H); ³¹P{¹H}

NMR (C₆D₆): l 93.5 (s).

Pyrrole (19.5 mg, 0.29 mmol) was added to a THF

solution (4 ml) of 1 (144.1 mg, 0.29 mmol) and the

reaction mixture was stirred for 12 h at r.t. After

removal of all volatile matter in vacuo, the residue was

extracted with hexane. Reducing the volume to approx-

i_¸m_¹a_¹te_¹ly_¹¹on_¹e_¹-ﬁ_¹f_ºth, light yellow crystals of trans-FeH-

NCHꢀCHCHꢀCH)(depe)₂(5a) were obtained (80 mg,

0.15 mmol, 52% yield). The reaction in NMR tube in

C₆D₆gave 5a in 95% yield. ¹H NMR (C₆D₆): l −27.94

(qui, J=49.5 Hz, 1H, Fe–H), 0.82 (br, 12H,

PCH₂CH₃), 0.92 (br, 12H, PCH₂CH₃), 1.01 (br, 4H,

PCH₂CH₃, partially overlapped with the peak at l

0.92), 1.40 (br, 8H, PCH₂CH₃, PCH₂CH₂P), 1.74 (br,

4H, PCH₂CH₃), 1.79 (br, 4H, PCH₂CH₂P), 1.94 (br,

4H, PCH₂CH₃), 6.21 (br, 2H, ring-H), 6.58 (br, 2H,

ring-H); ³¹P{¹H} NMR (C₆D₆): l 91.8 (s); IR (KBr):

w(Fe–H)=1854 cm⁻¹. Anal. Found: C, 53.94; H,

10.13; N, 2.79. Calc. for C₂₄H₅₃FeNP₄: C, 53.84; H,

9.98; N, 2.62%.

3.4. Reaction of 1 with furans

Furan (7.8 ml, 0.16 mmol) was added into a THF

solution (4 ml) of 1 (81.3 mg, 0.16 mmol) by a hypoder-

mic syringe and the resultant reaction mixture was

stirred for 12 h at r.t. After removal of all volatile

matter in vacuo, the orange oil was extracted with

hexane. Removal of hexane gave orange oil (84.6 mg).

The NMR spectrum showed formation of trans-

¸¹¹¹¹¹¹¹º

FeH(CꢀCHCHꢀCHO)(depe)₂(4a) in 47% yield. ¹H

NMR (C₆D₆): l −18.15 (qui, J=45.2 Hz, 1H, Fe–H),

1.00 (br, 12H, PCH₂CH₃), 1.1–2.1 (m, 36H, depe), 5.67

(br, 1H, aromatic-H), 6.44 (br, 1H, aromatic-H), 7.88

(br, 1H, aromatic-H); ³¹P{¹H} NMR (C₆D₆): l 96.6 (s).

Reactions of 1 with benzo[b]furan, 2,3-dihydrofuran,

2-acetylfuran, dibenzofuran, 2,5-dimethylfuran, 2,5-di-

hydrofuran, tetrahydrofuran, and 2,3-dihydro-benzo-

furan were carried out similarly in a NMR tube

without isolation._¸B_¹e_¹nz_¹o_¹[b_¹]f_ºuran and 2,3-dihydrofuran

3.6. Reaction of 1 with indole

A THF solution (4 ml) of 1 (83.2 mg, 0.17 mmol)

was added to indole (19.6 mg, 0.17 mmol) and then the

reaction mixture was stirred at r.t. for 20 h. After

removal of all volatile matter under reduced pressure,

the residue was extracted with hexane. The hexane

gave trans-FeH(CꢀCHC₆H₄O)(depe)₂(4b) and trans-

¸¹¹¹¹¹¹º

FeH(CꢀCHOCH₂CH₂)(depe)₂(4c), respectively. How-

T. Morikita et al. / Inorganica Chimica Acta 291 (1999) 341–354

351

solution was concentrated and kept at −30°C to give

3.9. Reaction of 2a with MeI

yellow crystals of a mixture of cis- and trans-

¸¹¹¹¹¹¹º

FeH(NC₆H₄CHꢀCH)(depe)₂(cis- and trans-5b) in 27%

isolated yield (24 mg, 0.045 mmol). Yields of cis- and

trans-5b were calculated as 23 and 12% yields, respec-

MeI (360 ml, 1.1 mmol) was added to a THF solution

(5 ml) of 2a (66.3 mg, 0.11 mmol). The color of the

solution immediately changed from orange to light

yellow. After removal of solvent in vacuo, the residue

was extracted with benzene. Evaporation of all volatile

matter under reduced pressure, followed by crystalliza-

tion from a mixture of benzene–hexane gave red crys-

tals of trans-FeI[(E)-CHꢀCHC₆H₄-2-SMe](depe)₂(7)

tively, by the NMR spectrum.

¸¹¹¹¹¹¹º

cis-FeH(NC₆H₄CHꢀCH)(depe)₂(cis-5b): ¹H NMR

(C₆D₆): l −9.20 (dq, J=87.8, 43.7 Hz, 1H, Fe–H),

0.4–2.1 (m, 48H, depe), 6.83 (br, 1H, oleﬁnic-H), 7.00

(br, 1H, oleﬁnic-H), 7.15 (1H, overlapped with the peak

of C₆D₅H), 7.92 (br, 2H, aromatic-H), 8.60 (br, 1H,

aromatic-H); ³¹P{¹H} NMR (C₆D₆): l 63.1 (dt, J=

27.3, 12.8 Hz, 1P), 82.4 (ddd, J=35.9, 27.3, 12.8 Hz,

1P), 88.8 (dt, J=125.7, 27.3 Hz, 1P), 90.4 (ddd, J=

1

(42.0 mg, 52%). H NMR (C₆D₆): l 0.85 (sext, J=7.5

Hz, 4H, PCH₂CH₃), 1.05 (br t, J=7 Hz, 24H,

PCH₂CH₃), 1.18 (m, 4H, PCH₂CH₂P), 1.41 (sext, J=

7.5 Hz, 4H, PCH₂CH₃), 1.85 (sext, J=7.5 Hz, 4H,

PCH₂CH₃), 2.01 (sext, J=7.5 Hz, 4H, PCH₂CH₂P),

2.05 (s, 3H, SCH₃), 2.84 (sext, J=7.5 Hz, 4H,

PCH₂CH₃), 6.43 (d, J=16.5 Hz, 1H, oleﬁnic-H), 6.84

(t, J=7.5 Hz, aromatic-H), 6.99 (d, J=7.5 Hz, 1H,

aromatic-H), 7.07 (t, J=7.5 Hz, 1H, aromatic-H), 7.20

(d, J=7.5 Hz, 1H, aromatic-H), 8.06 (dqui, J=16.5,

6.7 Hz, 1H, oleﬁnic-H); ³¹P{¹H} NMR (C₆D₆): l 70.2

(s); ¹³C{¹H} NMR (C₆D₆): l 5.9–25.7 (depe), 122.4 (s),

123.3 (s), 125.1 (s), 126.3 (s), 129.0 (s), 130.7 (s), 137.5

(br, s), 137.9 (s), 179.7 (qui, J=21.5 Hz); Anal. Found:

C, 46.21; H, 8.20; S, 4.90. Calc. for C₂₉H₅₇FeIP₄S: C,

46.79; H, 7.72; S, 4.31%.

125.7, 35.9, 12.8 Hz, 1P); Yield 23%.

¸¹¹¹¹¹¹º

trans-FeH(NC₆H₄CHꢀCH)(depe)₂(trans-5b): ¹H

NMR (C₆D₆): l −29.12 (qui, J=52.1 Hz, 1H, Fe–H),

0.4–2.1 (m, 48H, depe), 6.59 (br, 1H, oleﬁnic-H), 6.8

(br, 1H, overlapped with a peak of cis-5b), 7.05 (br,

1H, overlapped with a peak of cis-5b), 7.38 (br, 2H,

aromatic-H), 7.75 (br, 1H, aromatic-H); ³¹P{¹H} NMR

(C₆D₆): l 91.6 (s); Yield 12%. The following data were

obtained from the mixture of cis- and trans-5b: IR

(KBr) w(Fe–H)=2082 cm⁻¹. Anal. Found: C, 57.67;

H, 9.62; N, 2.53. Calc. for C₂₈H₅₅FeNP₄: C, 57.44; H,

9.47; N, 2.39%.

3.10. Reaction of 2a with H₂

3.7. Reaction of 1 with 2-acetylpyrrole

A THF solution (10 ml) of 2a (74.7 mg, 0.12 mmol)

was transferred into an autoclave by a hypodermic

syringe and 50 atm. of H₂was charged. After stirring

for 7 days at r.t., the reaction mixture was transferred

to a Schlenk tube under nitrogen atmosphere. After

removal of solvent, an orange powder was obtained.

Recrystallization of the powder from cold hexane gave

red crystals of the mixture of cis-FeH(SC₆H₄-2-Et)-

(depe)₂(cis-8) and trans-FeH(SC₆H₄-2-Et)(depe)₂

(trans-8) in 73% isolated yield (54.6 mg, 0.088 mmol).

The molar ratio of cis- and trans-8 was determined to

be 2.5:1 by the NMR spectrum.

2-Acetylpyrrole (17.1 mg, 0.16 mmol) was added to a

THF solution (4 ml) of 1 (78.0 mg, 0.16 mmol) and the

reaction mixture was stirred for 12 h at r.t. After

removal of all volatile matter in vacuo, the residue was

extracted with hexane. Removal of hexane gave a dark

¸¹¹¹¹¹¹¹¹¹¹¹¹º

red oil of crude FeH[NC(COMe)ꢀCHCHꢀCH](h²-

depe)(h¹-depe) (6) in 69% isolated yield (62.8 mg, 0.11

mmol). This product was characterized by spectroscopi-

1

cally. H NMR (C₆D₆): l −26.18 (ddd, J=63.3, 52.8,

47.9 Hz, 1H, Fe–H), 0.70 (dt, J=11.7, 8.1 Hz, 3H,

PCH₂CH₃), 0.84 (dt, J=12.6, 8.0 Hz, 3H, PCH₂CH₃),

0.9–2.1 (m, 42H, depe), 2.21 (s, 3H, COCH₃), 6.68 (br

d, J=2.7 Hz, 1H, aromatic-H), 7.23 (br, 2H, aromatic-

H); ³¹P{¹H} NMR (C₆D₆): l −18.2 (d, J=21.8 Hz,

1P), 48.9 (ddd, J=125.2, 37.1, 21.8 Hz, 1P), 95.6 (dd,

J=125.2, 37.1 Hz, 1P), 98.7 (t, J=37.1 Hz, 1P); IR

cis-8: ¹H NMR (C₆D₆): l −10.48 (dtd, J=69.9,

52.2, 30.2 Hz, 1H, Fe–H), 0.7–2.6 (m, 51H, depe,

C₆H₄CH₂CH₃), 3.38 (q, J=7.6 Hz, C₆H₄CH₂CH₃),

6.8–7.2 (m, 2H, aromatic-H, overlapped with the peaks

of trans-8 and C₆D₅H), 7.29 (t, J=7.7 Hz, 1H, aro-

matic-H), 8.58 (d, J=7.7 Hz, 1H, aromatic-H);

³¹P{¹H} NMR (C₆D₆): l 63.5 (dt, J=26.2, 18.4 Hz,

1P), 81.4 (ddd, J=133.7, 35.5, 18.4 Hz, 1P), 85.9 (ddd,

J=133.7, 35.5, 26.2 Hz, 1P), 91.1 (td, J=35.5, 18.4

Hz, 1P).

(KBr): w(Fe–H)=2088, w(CꢀO)=1652 cm⁻¹

.

3.8. Reaction of 2a with HCl

A 10-fold excess amount of HCl in Et₂O was added

into a hexane solution (2 ml) of 2a (16.5 mg, 0.027

mmol). After stirring for 15 min. at r.t., organic prod-

ucts were analyzed by gas liquid chromatography using

dibenzyl as an internal standard. 2,3-Dihydrobenzo-

[b]thiophene: 53% yield; benzo[b]thiophene, 10% yield.

1

trans-8: H NMR (C₆D₆): l −26.97 (qui, J=50.3

Hz, 1H, Fe–H), 0.7–2.6 (m, 51H, depe,

C₆H₄CH₂CH₃), 3.27 (q, J=7.5 Hz, 2H, C₆H₄CH₂CH₃),

6.8–7.2 (m, overlapped with the peaks of cis-8 and

C₆D₅H); ³¹P{¹H} NMR (C₆D₆): l 88.8 (s).

352

T. Morikita et al. / Inorganica Chimica Acta 291 (1999) 341–354

3.11. Thermolysis of 2a

reciprocal lattice on the imaging plate. The congeners

due to the thiaferracycle fragment were treated as half-

occupied and those due to the depe ligands were related

by a rotational displacement. All non-hydrogen atoms

were reﬁned anisotropically. All hydrogen atoms were

located on the ideal positions and were not reﬁned. The

ﬁnal R (R_w) value was 0.063 (0.085). The bond lengths

and angles for 2a cannot be discussed in detail because

of the disorder of the thiaferracycle fragment. The

crystallographic data of 2a are outlined in Table 5.

Single crystals of trans-5a suitable for X-ray crystal-

lography were obtained from cold hexane at −30°C. A

selected crystal was mounted in a glass capillary tube.

The reﬂections were collected with a Rigaku AFC-5S at

r.t. with graphite monochromated Mo Ka radiation

Compound 2a (13.0 mg, 0.022 mmol) was heated at

170°C for 1 h under argon in a glass tube without

solvent. After the pyrolysis, dibenzyl (3.0 mg, 0.0165

mmol) as an internal standard and hexane (0.6 ml) was

introduced in the tube. The GLC analysis of the hexane

solution showed re-formation of benzo[b]thiophene

(0.013 mmol, 58%).

3.12. Reaction of 2a with CO

Compound 2a (14.2 mg, 0.023 mmol) was placed in a

NMR tube with a PTFE valve (Aldrich^®) and benzene-

d₆(600 ml) was introduced into the NMR tube by a

trap-to-trap distillation. Carbon monoxide (1 atm.) was

charged to the NMR tube and warmed at 50°C for 48

h. 1,4-Dioxane was added to the NMR tube as an

internal standard and the NMR spectrum indicated the

formation of benzo[b]thiophene in 94% yield.

,

(u=0.71069 A). Using criterion ꢀF_oꢀ\3.0|(ꢀF_oꢀ), 4312

out of 7242 (3B2qB55.0°) reﬂections were used for

calculation and the reﬂection data/parameter ratio is

15.68. The product of the linear absorption coefﬁcient

(v=0.753 mm⁻¹) and the maximum crystal size (x=

0.70 mm) is 0.53 and the absorption correction was

therefore performed with c-scan methods. The R_int

value is 0.104. The structure was solved with direct

methods (^SAPI-91) and expanded by Fourier techniques

4. Crystallography

(

DIRDIF-94), and reﬁned by full-matrix least-squares

Deep red needles of 2a suitable for X-ray analysis

were obtained from a hexane solution at −30°C. After

removing the solution layer, the needles were carefully

washed with cold hexane and dried under vacuum. A

selected single crystal was sealed in a thin glass capil-

lary (GLAS, 0.7 mm o.d.) under nitrogen. The diffrac-

tion experiment was performed by a Rigaku RAXIS-IV

imaging plate area detector with graphite monochro-

techniques based on the te san program. The crystal

X

system is monoclinic and the space group P2₁/n (no.

14). All non-hydrogen atoms were reﬁned anisotropi-

cally and the hydrogen atoms were located on ideal

positions and were not reﬁned. The ﬁnal R (R_w) value is

0.044 (0.041). The crystallographic data are outlined in

Table 5.

Single crystals of 7 suitable for X-ray crystallography

were obtained from a mixture of benzene and hexane.

A deep red crystal with suitable size was selected and

mounted in a glass capillary tube. The reﬂections were

collected with a Rigaku AFC-5R at r.t. with graphite

,

mated Mo Ka radiation (u=0.71070 A) at −70°C. A

total of 3001 reﬂections was collected with a maximum

2q value of 55.5° and the reﬂection data/parameter

ratio is 12.1 (I\3.0|(I)). The R_mergevalue is 0.053.

Because the product of the linear absorption coefﬁcient

(v=0.790 mm⁻¹) and the maximum size of the crystal

(x=0.25 mm) is 0.2, the data were corrected for empir-

ical Lorentz and polarization effects and for secondary

extinction. The structure was solved by direct methods

,

monochromated Mo Ka radiation (u=0.71069 A). Us-

ing criterion ꢀF_oꢀ\3.0|(ꢀF_oꢀ), 1612 out of 4509 (6B

2qB54.9°) reﬂections were used for calculation and the

reﬂection data/parameter ratio is 5.99. The product of

the linear absorption coefﬁcient (v=1.546 mm⁻¹) and

the maximum crystal size (x=0.20 mm) is 0.31 and the

absorption correction was therefore applied with c-

scan methods. The R_intvalue is 0.104. The structure

was solved with Paterson methods (^PATTY) and ex-

panded by Fourier techniques (^DIRDIF-92), and reﬁned

by full-matrix least-squares techniques based on the

(

SHELXS-86 [18]), expanded by Fourier techniques

DIRDIF-94 [19]), and reﬁned by full-matrix least-

squares techniques based on the teXsan program [20].

The crystal system is monoclinic and the space group is

determined as C2/c (no. 15) suggesting the unit cell has

a 1:1 disorder of the thiaferracycle fragment. It is worth

noting that, although the reﬁnement with the alterna-

tive possible space group Cc failed, the trial suggested

that the atoms of two depe ligands have the C₂symme-

try and the thiaferracycle fragments disordered with a

1:1 population have a C₂symmetry on the same C₂axis

as the depe ligands. Disorder with a 1:1 population may

be caused when the reﬂection data were measured with

half of the real lattice constants. However, that possi-

bility was excluded because no spot was observed in the

teXsan program. The crystal system is orthorhombic

and the space group P2₁2₁2₁(no. 19). All non-hydrogen

atoms were reﬁned anisotropically and the hydrogen

atoms were located on ideal positions and were not

reﬁned. The ﬁnal R (R_w) value is 0.062 (0.071). The

crystallographic data are outlined in Table 5. These

crystallographic data are available by application to the

Cambridge Crystallographic Data Centre (CCDC

116677-116679).

T. Morikita et al. / Inorganica Chimica Acta 291 (1999) 341–354

353

Table 5

¸¹¹¹¹¹¹¹º

Crystallographic data for Fe(SC₆H₄CHꢀCH)(depe)₂(2a), trans-FeH(NCHꢀCHCHꢀCH)(depe)₂(5a), and trans-FeI[(E)-CHꢀCHC₆H₄-2-

SMe](depe)₂(7)

2a

5a

7

Chemical formula

Formula weight

Crystal system

Space group

C₂₈H₅₄FeP₄S

602.54

C₂₄H₅₃NFeP₄

535.43

monoclinic

P2₁/n (No. 14)

9.986(5)

18.153(5)

16.005(7)

93.44(4)

2896(1)

4

1.228

7.53

C₂₉H₅₇FeIP₄S

744.48

orthorhombic

P2₁2₁2₁(No. 19)

13.486(3)

monoclinic

C2/c (No. 15)

13.569(4)

16.898(4)

14.542(3)

114.08(2)

3044

,

a (A)

,

b (A)

24.653(8)

10.605(3)

,

c (A)

i (°)

3

,

V (A )

Z

3525(1)

4

1.402

15.46

3.0–54.9

2q–ꢀ

4

D_calc(g cm⁻¹

)

1.315

7.90

55.5 (max.)

v (cm⁻¹

2q (°)

)

3.0–55.0

2q–ꢀ

Scan type

Diffractometer

Radiation

Rigaku RAXIS-IV

Mo Ka

graphite

Rigaku AFC5S

Mo Ka

graphite

7242

4313 (ꢀF_oꢀ\3|ꢀF_oꢀ)

direct methods (SAPI-91)

0.044

Rigaku AFC5R

Mo Ka

graphite

Monochromator

No. data collected

No. of observed

Method of phase determination

3001

4509

1843 (ꢀF_oꢀ\3|ꢀF_oꢀ)

1612 (ꢀF_oꢀ\3|ꢀF_oꢀ)

direct methods (SHELXS-86)

Paterson methods (PATTY)

a

R

0.063

0.085

1.53

0.062

0.071

1.87

b

R_w

0.041

2.32

Goodness-of-ﬁt indicator

^aR=S(ꢀꢀF_oꢀ−ꢀF_cꢀꢀ)/SꢀF_oꢀ.

2 0.5

^bR_w=[Sw(ꢀF_oꢀ−ꢀF_cꢀ)²/SwꢀF_oꢀ ]

.

Choi, R.J. Angelici, Organometallics 10 (1991) 2436. (l) M.-G.

Choi, R.J. Angelici, Inorg. Chem. 30 (1991) 1417. (m) J. Chen,

Y. Su, R.A. Jacobson, R.J. Angelici, J. Organomet. Chem. 428

(1992) 415. (n) J.W. Benson, R.J. Angelici, Inorg. Chem. 32

(1993) 1871. (o) M.J. Sanger, R.J. Angelici, Organometallics 13

(1994) 1821.

Acknowledgements

We thank Professors M. Akita and Y. Moro-oka,

and Mr M. Yoshizawa of Tokyo Institute of Technol-

ogy for X-ray data collection for trans-5a and for

helpful discussions. This work was ﬁnancially sup-

ported by a Grant-in-Aid for Scientiﬁc Research from

the Ministry of Education, Science, Sports and Culture,

Japan, by the Proposal Based New Industry Creative

Type Technology R&D Promotion Program from the

New Energy and Industrial Technology Development

Organization (NEDO) of Japan, and by a research

project of the DIA Research Institute, Inc., commis-

sioned by the Petroleum Energy Center with a subsidy

of the Ministry of International Trade and Industry.

[2] (a) C. Bianchini, D. Fabbri, S. Gladiali, A. Meli, W. Pohl, F.

Vizza, Organometallics 15 (1996) 4604. (b) C. Bianchini, A. Meli,

M. Peruzzini, F. Vizza, S. Moneti, V. Herrera, R.A. Sa´nchez-

Delgado, J. Am. Chem. Soc. 116 (1994) 4370. (c) C. Bianchini, P.

Frediani, V. Herrera, M.V. Jime´nez, A. Meli, L. Rinco´n, R.

Sa´nchez-Delgado, F. Vizza, J. Am. Chem. Soc. 117 (1995) 4333.

(d) C. Bianchini, A. Meli, M. Peruzzini, F. Vizza, V. Herrera, R.

Sa´nchez-Delgado, Organometallics 13 (1994) 721. (e) R.A.

Sa´nchez-Delgado, V. Herrera, L. Rinco´n, A. Andriollo, G.

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Article Doi

C-S, C-H, and N-H bond cleavage of heterocycles by a zero-valent iron complex, Fe(N2)(depe)2 [depe=1,2-bis(diethylphosphino)ethane]

DOI: 10.1016/s0020-1693(99)00146-2

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Full text of DOI:10.1016/s0020-1693(99)00146-2

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