Synthesis, structure and possible formation pathway of a novel cobalt carbonyl compound with new type B-O bond, Co(CO)3 (PPh3)2BEt3, and mixed metal Co-Fe-S cluster with possible nonlinear optical property, [Et4N][CoFe2 (CO)8S(PPh3)]

Article abstract of DOI:10.1016/S0022-328X(02)01568-1

Reaction of Co(CNS)₂ with Fe₂S₂(CO)₆, LiBEt₃H and PPh₃ in THF-MeCN resulting in a novel cobalt carbonyl complex, Co(CO)₃(PPh₃)₂BEt₃ (1) and mixed-metal Co-Fe-S cluster compound, [Et₄N]Fe₂Co(CO)₈S(PPh₃)] (2). The structures of 1 and 2 were determined from X-ray three dimension data. Structure studies reveal that 1 is a new cobalt carbonyl complex containing a novel B-O bond of 1.601(5) ? in which the oxygen atom is from metal carbonyl and the B atom is from BEt₃ and 2 contained a triangular pyramid mixed-metal Co-Fe-S core [CoFe₂S]^- with Co-S of 2.189, Fe-S of 2.208, Co-Fe of 2.56 and Fe-Fe of 2.58 ?. Theoretical calculation on 1 and 2 shows that B-O bonding energy of complex 1 is lower than that of normal covalent bonding and 2 possesses a calculated nonlinear optical first molecular hyperpolarizability component of 28.5 × 10^-30 esu. The possible formation pathway of 1 and 2 was discussed.

Full text of DOI:10.1016/S0022-328X(02)01568-1

Journal of Organometallic Chemistry 655 (2002) 233Á238
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www.elsevier.com/locate/jorganchem
Synthesis, structure and possible formation pathway of a novel cobalt
carbonyl compound with new type BÃO bond, Co(CO)3(PPh3)2BEt3,
S cluster with possible nonlinear optical
/
and mixed metal CoÃ
/
FeÃ
/
property, [Et4N][CoFe2(CO)8S(PPh3)]
Botao Zhuang *, Haofen Sun, Lingjie He, Zhangfeng Zhou, Chensheng Lin,
Kechen Wu, Zixiang Huang
Fujian Institute of Research on the Structure of Matter, State Key Laboratory of Structural chemistry, Chinese Academy of Sciences, Fuzhou, Fujian
350002, People’s Republic of China
Received 18 February 2002; accepted 29 April 2002
Abstract
Reaction of Co(CNS)2 with Fe2S2(CO)6, LiBEt3H and PPh3 in THFÃ
Co(CO)3(PPh3)2BEt3 (1) and mixed-metal CoÃFeÃS cluster compound, [Et4N][Fe2Co(CO)8S(PPh3)] (2). The structures of 1 and 2
were determined from X-ray three dimension data. Structure studies reveal that 1 is a new cobalt carbonyl complex containing a
/MeCN resulting in a novel cobalt carbonyl complex,
/
/
˚
novel BÃ
triangular pyramid mixed-metal CoÃ
Theoretical calculation on 1 and 2 shows that BÃ
2 possesses a calculated nonlinear optical first molecular hyperpolarizability component of 28.5ꢁ
pathway of 1 and 2 was discussed. # 2002 Elsevier Science B.V. All rights reserved.
/
O bond of 1.601(5) A in which the oxygen atom is from metal carbonyl and the B atom is from BEt3 and 2 contained a
˚
Fe of 2.58 A.
/
FeÃ
/
S core [CoFe2S]ꢀ with CoÃ
O bonding energy of complex 1 is lower than that of normal covalent bonding and
10ꢀ30 esu. The possible formation
/
S of 2.189, FeÃ
/
S of 2.208, CoÃ
/
Fe of 2.56 and FeÃ
/
/
/
Keywords: CoÃ
/
B compound; CoÃ
/
FeÃS compound; Synthesis and structure; Theoretical chemical calculation
/
1. Introduction
Herein, we report a new cobalt carbonyl compound with
novel BÃO bond, Co(CO)3(PPh3)2BEt3 (1), and new
CoÃFeÃS cluster compound possessing possible non-
linear optical property, [Et4N][CoFe2(CO)8S(PPh3)] (2),
from the reaction of diirondisulfide hexacarbonyl dia-
nion with Co(SCN)2 and PPh3. Preliminary theoretical
calculation and the reaction pathway were also dis-
cussed.
/
Diirondisulfide hexacarbonyl has been a versatile and
attractive reagent for formation of mixed metallic poly-
nuclear cluster compounds, and the chemistry of this
reagent and the compounds from the reaction involving
this reagent has interested chemists since the dianion of
this reagent, [Fe2S2(CO)6]2ꢀ was synthesized [1]. As a
/
/
part of our investigation on metalÁ
plexes containing low- and mixed-valence metal atoms,
we have reported several metalÁsulfur cluster complexes
/
sulfur cluster com-
/
2. Results and discussion
with different configuration and coordination mode of
[Fe2S2(CO)6]-units from the reaction of diirondisulfide
hexacarbonyl dianion with different metal complexes,
2.1. The structure of Co(CO)3BEt3(PPh3)2 (1) and
novel BÃ/O bonding
[Cu5Fe6S6(CO)18(PPh3)2]ꢀ
(S2CNEt2)]ꢀ (Mꢂ
[2]
[MFe2S2(CO)8-
/
Mo, W) [3] and [Fe6S6(CO)12]2ꢀ [4]
The selected bond distances and bond angles of 1 are
given in Table 1 and the molecular structure of 1 is
depicted in Fig. 1. As shown in Fig. 1, 1 is a neutral
molecule with Co atom in zero oxidation state. The Co
* Corresponding author. Fax: ꢃ
/
86-591-371-4946.
E-mail address: zbt@ms.fjirsm.ac.cn (B. Zhuang).
0022-328X/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 1 5 6 8 - 1

234
B. Zhuang et al. / Journal of Organometallic Chemistry 655 (2002) 233Á238
/
Table 1
nyls resulting in five coordination of cobalt atom. CoÃ
/
C
˚
˚
bond distances of 1.773(4), 1.766(4) and 1.891(3) A in 1
Selected bond distances (A) and angles (8) for Co(PPh3)2(CO)3BEt3 (1)
˚
are similar to that of SCo3(CO)9 (1.75 and 1.78 A) [5]. It
Bond distances
is worth pointing out that 1 contains a novel BÃ
/
O
CoÃP(1)
CoÃP(2)
CoÃC(1)
CoÃC(2)
2.2087(13) O(3)ÃB
2.2095(13) O(1)ÃC(1)
1.601(5)
1.136(4)
1.147(4)
1.157(4)
1.622(6)
1.620(5)
1.621(5)
1.546(6)
1.536(6)
1.511(6)
bonding, of which the oxygen atom comes from a
carbonyl ligand of metal carbonyl. In our knowledge,
1.773(4)
1.766(4)
1.891(3)
1.827(3)
1.827(3)
1.829(3)
1.822(3)
1.820(3)
1.827(3)
O(2)ÃC(2)
O(3)ÃC(3)
BÃC(4)
BÃC(6)
BÃC(8)
C(4)ÃC(5)
C(6)ÃC(7)
C(8)ÃC(9)
there are four kinds of BÃ
/
O bonding: (i) B links with the
CoÃC(3)
oxygen atom from organic alkoxide, OR ligand, (ii) B
connects with the oxygen atom only resulting in borate,
(iii) B as in B3O3 links to the oxygen atom from
triosmium oxymethylidyne [6] and (iv) B coordinates
to the oxygen atom from organic carbonyl forming an
adduct [7]. Compound 1 is the first compound with
P(1)ÃC(11)
P(1)ÃC(21)
P(1)ÃC(31)
P(2)ÃC(41)
P(2)ÃC(51)
P(2)ÃC(61)
Bond angles
bonding of B to the oxygen atom from metal carbonyl.
˚
O bond distance of 1 (1.601(5) A) is obviously larger
P(1)ÃCoÃP(2)
P(1)ÃCoÃC(1)
P(1)ÃCoÃC(2)
P(1)ÃCoÃC(3)
P(2)ÃCoÃC(1)
P(2)ÃCoÃC(2)
P(2)ÃCoÃC(3)
C(1)ÃCoÃC(2)
C(1)ÃCoÃC(3)
C(2)ÃCoÃC(3)
CoÃP(1)ÃC(11)
CoÃP(1)ÃC(21)
CoÃP(1)ÃC(31)
C(11)ÃP(1)ÃC(21)
C(11)ÃP(1)ÃC(31)
C(21)ÃP(1)ÃC(31)
CoÃP(2)ÃC(41)
CoÃP(2)ÃC(51)
CoÃP(2)ÃC(61)
C(41)ÃP(2)ÃC(51)
C(41)ÃP(2)ÃC(61)
C(51)ÃP(2)ÃC(61)
BÃO(3)ÃC(3)
175.82(4)
O(3)ÃBÃC(6)
106.2(3)
105.4(3)
113.4(3)
113.5(3)
111.7(3)
179.2(3)
177.6(4)
178.4(4)
113.1(3)
116.2(3)
116.2(4)
120.5(3)
121.3(3)
121.6(3)
123.3(3)
121.0(3)
121.8(3)
122.1(3)
120.2(2)
118.0(3)
123.4(3)
120.0(3)
121.6(3)
BÃ
/
90.52(11) O(3)ÃBÃC(8)
90.92(11) C(4)ÃBÃC(6)
˚
than that of Na3B3O6 (1.433 and 1.280 A), K3B3O6
˚
(1.398 and 1.331 A), Ba3(B3O6)2 (1.397 and 1.332 A) [8],
˚
88.69(9)
C(4)ÃBÃC(8)
˚
LiB3O5 (1.469 and 1.336 A) [9], CsB2O5 (1.48 and 1.38
˚
A) [10] and boron-containing organic compounds, for
˚
example, (2,4,6-C6H2(CH3)3)2BOCH3 (1.352(5) A) [11]
90.54(11) C(6)ÃBÃC(8)
92.02(11) CoÃC(3)ÃO(3)
87.28(9)
CoÃC(2)ÃO(2)
120.62(17) CoÃC(1)ÃO(1)
119.94(16) BÃC(4)ÃC(5)
and that of the (iii) type of compound (m-
˚
1.25(6) A) [6].
H)3Os3(CO)9(m3-C)(O3B3O3) (1.39(6)Á
/
119.44(15) BÃC((6)ÃC(7)
114.72(11) BÃC(8)ÃC(9)
These imply that the BÃ
possesses a different bonding nature from the (i) to
(iii) kinds of BÃO bond. Noteworthy, BÃO bonding of 1
/
O bonding observed in 1
114.97(12) P(1)ÃC(11)ÃC(12)
112.95(11) P(1)ÃC(11)ÃC(16)
105.24(15) P(1)ÃC(21)ÃC(22)
104.59(16) P(1)ÃC21)ÃC(26)
103.14(16) P((1)ÃC31)ÃC(32)
114.05(11) P(1)ÃC31)ÃC(36)
114.31(11) P(2)ÃC(41)ÃC(42)
115.25(11) P(2)ÃC(41)ÃC(46)
105.05(15) P(2)ÃC51)ÃC(52)
104.32(16) P(2)ÃC(51)ÃC(56)
102.52(15) P(2)ÃC(61)ÃC(62)
/
/
seems to be similar to that of the (iv) type adducts
formed between B(C6F5)3 and various organic carbonyl
compounds because in both of them, the B atoms are
coordinated by oxygen atom from carbonyl and the BÃ
O bond distances of them are comparable, for example,
the BÃO bond lengths of PhC(X)OÃB(C6F5)3 (XꢂH,
Me, OEt, NPr2) are in 1.52(1)Á1.610(8) A [7]. However,
/
/
/
/
˚
/
178.0(3)
P(2)ÃC(61)ÃC(66)
there are obvious differences between them: (a) in 1, the
oxygen atom coordinating to B is from metal carbonyl
and in the (iv) type adducts, the oxygen atom is from
O(1)ÃBÃC(4)
105.9(3)
organic carbonyl; (b) in 1, the BÃ
(almost linear coordination geometry) and in the (iv)
type adducts, the BÃOÃC angles are in 126.7(5)Á
/
OÃC angle is 178.0(3)8
/
/
/
/
138.2(4)8. Thus, different carbonyl (triple bond in
compound 1 and double bond in the (iv) type adducts)
and different coordination geometries (linear coordina-
tion geometry in compound 1 and bending geometries in
the (iv) type adducts) addition to the cobalt atom with
19 electrons in 1 lead to somewhat different BÃ
/
O
bonding nature. Also, it should be pointed out that
linking of BEt3 to the carbonyl of cobalt(0) in 1 enlarges
˚
C(3) bond distance (1.891(3) A)
the corresponding CoÃ
/
and somehow stabilized the cobalt(0)-complex,
[Co(CO)3(PPh3)2], which is unstable because of its
cobalt atom possessing 19 electrons running counter to
18-electron configuration. In order to understand the
Fig. 1. Structure of complex Co(PPh3)2(CO)3BEt3 (1).
BÃ
/
O bonding nature and confirm the structure of
complex 1, a theoretical calculation has been done.
Using density function theory (ADF) [12a,12b] and
GAUSSIAN 98w program [12c] to calculate molecule
atom is located at the center of triangle in the trigonal
bipyramid consisting of two phosphor atoms from the
phosphine ligands and three carbon atoms from carbo-
Co(CO)3(PPh3)2×
/
BEt3 (1), the results of ADF with the

B. Zhuang et al. / Journal of Organometallic Chemistry 655 (2002) 233Á
/
238
235
double theta basis sets indicate that the bonding energy
between Co(CO)3(PPh3)2 and BEt3 groups is 13.1 kcal
molꢀ1, which is lower than the normal covalence
Table 2
˚
Selected bond distances (A) and angles (8) for [Et4N][Co-
Fe2(CO)8S(PPh3)] (2)
bonding. This result is in agreement with the slightly
˚
Bond distances
long BÃ/O bond (1.601 A). In order to demonstrate that
CoÃFe(2)
CoÃFe(1)
CoÃS
2.5511(7)
2.5626(7)
Fe(2)ÃC(5)
Fe(2)ÃC(4)
1.779(4)
1.813(5)
1.838(3)
1.824(3)
1.831(4)
1.140(7)
1.135(5)
1.135(5)
1.130(5)
1.139(5)
1.124(5)
1.153(5)
1.143(5)
the molecular energy vary with distance between the two
groups, the Scan function of GAUSSIAN 98w with
LANL2DZ basis sets was carried out (as shown in
Fig. 2). It was found that the energy minimized point
2.1885(10) PÃC(11)
2.1868(10) PÃC(21)
1.739(4)
1.772(4)
2.5841(8)
CoÃP
CoÃC(7)
CoÃC(8)
Fe(1)ÃFe(2)
Fe(1)ÃS
Fe(1)ÃC(3)
Fe(1)ÃC(1)
Fe(1)ÃC(2)
F(2)ÃS
PÃC(31)
O(1)ÃC(1)
O(2)ÃC(2)
˚
was near 1.65 A, which is quite in agreement with X-ray
˚
2.2197(10) O(3)ÃC(3)
result (1.601 A of BÃ
/O distance in 1). The highest
1.769(4)
1.773(4)
1.777(4)
O(4)ÃC(4)
O(5)ÃC(5)
O(6)ÃC(6)
occupied molecular orbital (HOMO) is non-bonding
orbital occupied by the unpaired electron, and its main
component is contributed from Co(CO)3(PPh3)2. It is
interesting to note that if we performed a geometry
optimized at the part of Co(CO)3(PPh3)2, the band angle
2.1959(10) O(7)ÃC(7)
1.772(4)
F(2)ÃC(6)
O(8)ÃC(8)
Bond angles
Fe(1)ÃCoÃFe(2)
Fe(1)ÃCoÃS
of PÃ
1808, while this angle in compound 1 is 176.88. The PÃ
CoÃP bonds slightly bending to the group BEt3 is
/
CoÃ
/
P of the equilibrium structure would lead to
60.71(2)
50.02(3)
132.50(3)
CoÃFe(2)ÃC(4)
Fe(1)ÃFe(2)ÃS
Fe(1)ÃFe(2)ÃC(6)
102.49(13)
54.61(3)
/
Fe(1)ÃCoÃP
94.30(14)
100.65(14)
154.55(15)
104.96(14)
148.93(13)
100.64(15)
94.5(2)
/
Fe(1)ÃCoÃC(7)
Fe(1)ÃCoÃC(8)
Fe(2)ÃCoÃS
72.16(12) Fe(1)ÃFe(2)ÃC(5)
130.68(13) Fe(1)ÃFe(2)ÃC(4)
54.55(3)
144.06(3)
reasonable because there is interaction between the
HOMO of Co(CO)3(PPh3)2 and BEt3, whose energies
were near to each other. The interaction causes the
energy gap of HOMO and LUMO to increase from 0.15
a.u. of the group Co(CO)3(PPh3)2 to 0.34 a.u. of
compound 1. The variety of the energy gap indicates
that the addition group BEt3 leads to stabilization of the
molecule.
SÃFe(2)ÃC(6)
SÃFe(2)ÃC(5)
Fe(2)ÃCoÃP
Fe(2)ÃCoÃC(7)
Fe(2)ÃCoÃC(8)
SÃCoÃP
SÃCoÃC(7)
SÃCoÃC(8)
PÃCoÃC(7)
PÃCoÃC(8)
C(7)ÃCoÃC(8)
CoÃFe(1)ÃFe(2)
CoÃFe(1)ÃS
CoÃFe(1)ÃC(1)
CoÃFe(1)ÃC(2)
CoÃFe(1)ÃC(3)
Fe(2)ÃFe(1)ÃS
Fe(2)ÃFe(1)ÃC(3)
Fe(2)ÃFe(1)ÃC(1)
Fe(2)ÃFe(1)ÃC(2)
SÃFe(1)ÃC(3)
SÃFe(1)ÃC(1)
SÃFe(1)ÃC(2)
C(3)ÃFe(1)ÃC(1)
C(3)ÃFe(1)ÃC(2)
C(1)ÃFe(1)ÃC(2)
CoÃFe(1)ÃFe(2)
CoÃFe(2)ÃS
116.60(12) SÃFe(2)ÃC(4)
78.47(13) C(6)ÃFe(2)ÃC(5)
102.13(4)
C(6)ÃFe(2)ÃC(4)
98.58(19)
100.1(2)
71.16(3)
123.45(12) C(5)ÃFe(2)ÃC(4)
121.27(12) CoÃSÃFe(2)
98.94(12) CoÃSÃFe(1)
96.75(13) Fe(1)SÃFe(2)
107.27(17) CoÃPÃC(11)
71.09(3)
71.64(3)
116.37(12)
112.45(12)
117.22(11)
101.53(16)
103.28(16)
104.10(17)
168.9(3)
2.2. The structure and calculated optical nonlinearity of
[Et4N][CoFe2(CO)8S(PPh3)] (2)
59.43(2)
CoÃPÃC(21)
CoÃPÃC(31)
53.89(3)
103.86(13) C(11)ÃPÃC(21)
102.44(12) C(11)ÃPÃC(31)
148.48(15) C(21)ÃPÃC(31)
The selected bond distances and bond angles of 2 are
listed in Table 2 and the anion of 2 is depicted in Fig. 3.
Compound 2 consisted of a cation Et4Nꢃ and an anion
[CoFe2(CO)8S(PPh3)]ꢀ. As shown in Fig. 3, the anion,
[CoFe2(CO)8S(PPh3)]ꢀ, contained a [CoFe2S]ꢀ core,
which possessed a slightly distorted triangular pyramid
geometry, the apical was occupied by a sulfur atom and
53.75(3)
CoÃC(7)ÃO(7)
97.91(14) CoÃC(8)ÃO(8)
91.88(214 Fe(1)ÃC(1)ÃO(1)
160.80(12) Fe(1)ÃC(2)ÃO(2)
95.56(15) Fe(1)ÃC(3)ÃO(3)
144.52(14) Fe(2)ÃC(4)ÃO(4)
111.72(13) Fe(2)ÃC(5)ÃO(5)
173.9(4)
177.9(4)
178.2(4)
177.8(4)
178.8(4)
179.1(4)
98.1(2)
Fe(2)ÃC(6)ÃO(6)
177.6(4)
119.6(3)
95.96(18) PÃC(11)ÃC(12)
99.25(19) PÃC(11)ÃC(16)
59.43(2)
54.28(3)
121.9(3)
122.3(3)
PÃC(21)ÃC(22)
PÃC(21)ÃC(26)
120.0(3)
118.0(3)
124.0(3)
CoÃFe(2)ÃC(6)
CoÃFe(2)ÃC(5)
152.73(14) PÃC(31)ÃC(32)
98.63(14) PÃC(31)ÃC(36)
the base was CoFe2 triangle. Around the core there were
six carbonyl ligands coordinating to the iron atoms and
two carbonyls and one PPh3 ligand connecting with the
Co atom leading to four-coordination of cobalt and
each iron atoms. This is the first structure determination
of the anion compound containing triangular pyramid
core CoFe2S, although the preparation [13] of
[CoFe2(CO)9S]ꢀ and [CoFe2(CO)9SNO] and the struc-
ture of the later [14] have been reported more than 10
Fig. 2. The molecular energy varied with the BÃO bond length for 1.
/

236
B. Zhuang et al. / Journal of Organometallic Chemistry 655 (2002) 233Á238
/
in the direction of Co to bisection point of the two Fe
atoms, the calculated bxxx component is about 28.5ꢁ
10ꢀ30 esu (lꢂ
1.064 mm), which is about 100 times
/
/
larger than the average b value of a urea molecule [19].
The rest b components of the cluster are all less than
7.0ꢁ
component of dipole moment is also X direction with
mx ꢂ 11.4 Debye, while my and mz has only 1.4 and
4.1 Debye, respectively. These results indicate that this
/
10ꢀ30 esu, and it is found that the largest
/
ꢀ
/
ꢀ
/
molecular cluster might have great potential to be
second-harmonic generation material, which has its
application in optical communication device.
2.3. The synthetic reaction and possible formation
pathway of products
Fig. 3. Structure of the anion of the complex, [Et4N][Co-
Fe2(CO)8S(PPh3)] (2).
As is described above, it can be found evidently that
(i) the product 1 contains a Co0 atom with five
coordination geometry and product 2 possesses a Coꢃ
ion with distorted tetrahedral coordination geometry;
(ii) Co atoms in both product 1 and 2 have carbonyl
ligands, (iii) product 2 contains a [Fe2S(CO)6]2ꢀ unit
which could be considered as an incomplete
Fe2S2(CO)26ꢀ unit with losing one of its two sulfur
atoms and low valence iron atoms, Fe0, and (iii)
according to the reaction of Co2(CO)8 with PPh3 [20]
and the IR data of its products [Co(CO)3(PPh3)2]-
[Co(CO)4] (2002, 1883 cmꢀ1), [Co(CO)3(PPh3)2][BPh4]
(2004 cmꢀ1) and [Co(CO)3(PPh3)2][Cr(SCN)4(NH3)2]
(2014, 1944 cmꢀ1) [21], the 1986 and 1930 cmꢀ1
absorption of 3 implied that compound 3 possessed a
trigonal bipyramid configuration like [Co(CO)3-
(PPh3)2]ꢃ. Thus, it is evident that the synthetic reaction
involves the substitution of carbonyl and phosphine for
SCN-ligands, reduction of cobalt ion Co2ꢃ and iron
ions FeI, desulfurization process and participation of
Fe2S2(CO)26ꢀ as a building block come from the
reaction of [Fe2S2(CO)6] with LiBEt3H [1]. Taking the
reactants, reaction condition used and phenomenon
observed during the reaction process together into
years ago. The average bond lengths of MÃ
MÃS (2.20(2)), MÃCax (1.76(2)), MÃCeq (1.78(2)), CÃ
(1.14(1) A) and bond angles of MÃSÃM (71.3(3)), MÃ
MÃS (54(2)), CeqÃMÃCeq (97(2)), CeqÃMÃCax (100(5)8)
in the anion of 2 [15] are comparable with that in the
neutral compound, [CoFe2(CO)8NO] (MÃM, 2.56(2);
MÃS, 2.16(3); MÃCax, 1.79(2); MÃCeq, 1.78(3); CÃO,
1.13(2) A and MÃSÃM, 72.5(2); MÃMÃS, 54(1); CeqÃ
MÃCeq, 99(7); CeqÃMÃCax, 101(7)8). The fact that CoÃ
/M (2.57(2)),
/
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/
/O
˚
/
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/
/
/
/
/
/
/
˚
m3-S bond length of 2.189 A in 2 is very similar to that in
Co(I)-complex, [SCo3(CO)7]2S2, [16] indicated that the
oxidation state of cobalt atom in 2 is ꢃ1, thus, the
/
oxidation states of the two iron atoms in 2 should be
zero in terms of the principle of electric charge balance.
˚
Fe bond distance of 2.5841(8) A in 2 is
In fact, the FeÃ
/
approximate to the one in Fe0-complex, Fe3(CO)9S2ꢀ
˚
Fe, 2.58 A). The SFe2(CO)6 unit of 2 could be
(FeÃ
/
considered as an incomplete Fe2S2(CO)26ꢀ unit with
losing one of the sulfur atoms and reduction of each
Feꢃ1 to Fe0 because the configuration of the two
Fe(CO)3 fragments including the FeÃ
/
Fe bond distance
˚
(2.5841(8) A) in 2 is very similar to those in starting
material [Fe2S2(CO)6]2ꢀ (FeÃ
skeleton electron number of 2 is 48 and three metalÃ
metal bonds (one FeÃFe and two FeÃCo bonds) were
observed in 2. This showed that the structure of 2
complied with the 2(9NꢀL) (Nꢂnumber of metal and
Lꢂnumber of metalÃmetal bonds) rule [18].
/
˚
Fe, 2.54 A) [1,17]. The
/
/
/
/
/
/
/
By using density functional theory (DFT) method, the
frequency-dependent first hyperpolarizabilities of the
molecular cluster, [Et4N][CoFe2(CO)8S(PPh3)] (2), was
determined with the widely used local density approx-
imation (LDA) and the asymptotically correct Van
LeeuwenÁBaerends (LB94) potential. The triple basis
/
set was used and the frozen-core is up to 3p for Fe and
Co, 2p for P and 1s for C and O. If we let the x-axis lie
Scheme 1.

B. Zhuang et al. / Journal of Organometallic Chemistry 655 (2002) 233Á
/
238
237
account, the synthetic reaction and reaction pathway
could be proposed as in Scheme 1.
As shown in Scheme 1, [Fe2S2(CO)6 reacts with
LiBEt3H in the presence of Et4NCl affording
[Fe2S2(CO)6]2ꢀ [1], Co(SCN)2 reacts with PPh3 in the
presence of carbon monoxide (from dissociation of
1.5 ml of LiBHEt3ÁTHF (it could be seen that the
/
solution drops on the wall of the flask were green), and
the blue solution A in turn, resulting in deep-red
reaction mixture. The reaction mixture was stirred for
more than 20 min and then, the cool bath was removed.
After the temperature rose to r.t., the mixture was
stirred continuously in r.t. for another 48 h. Filtering
out the dark residue, the dark filtrate was cooled at
4 8C for several days. Black sparkling crystalline
product (0.1 g) was obtained by filtration, washed
with isopropanol and dried in vacuum (Yield: 17.4%).
Anal. Calc. for C34H35CoFe2NO8PS: C, 49.8; H, 4.3;
Co, 7.2; Fe, 13.7; N, 1.7. Found: C, 50.5; H, 4.4; Co, 6.9;
Fe, 14.1; N, 1.9%. IR (KBr pellet) 2025s, 1967s, 1946s,
1905s and 1855s (nCO), X-ray crystallography study
indicated that this product was [Et4N][Co-
Fe2(CO)8S(PPh3)] (2). The filtrate was concentrated by
vacuum to volume of 15 ml, 20 ml of isopropanol was
added and 0.02 g of yellow brown crystals were obtained
by filtration and dried in vacuum. Anal. Calc. for
C45H45CoBO3P2: C, 70.6; H, 5.9; Co, 7.7. Found: C,
69.8; H, 6.5; Co, 8.2%. IR (KBr pellet): 2000s, 1942s
[Fe2S2(CO)6])2ꢀ] and LiBEt3H resulting in Coꢃ Ã
PPh3Ã
CO complex, [Co(PPh3)2(CO)3]ꢃ (3), and this
Coꢃ Ã
/
/
/
PPh3Ã
/
CO complex 3 further reacts with LiBEt3H
affording the Co0-complex, Co(PPh3)2(CO)3BEt3 (1) as
a side product in a very low yield. In terms of the
expected reactivity of [Fe2S2(CO)6]2ꢀ [1,2,22Á
24] the
/
[Co(PPh3)2(CO)3]ꢃ (3) would react with [Fe2S2(CO)6]2ꢀ
leading to a precursor product, [CoFe2S2(CO)8(PPh3)]ꢀ
(4) which should be similar to the known CoÃ
/
FeÃ
/
S
compound,
(MeC5H4)2Cr(m-SCMe3)2(m3-S)2Co(m3-
S)2Fe2(CO)6 [25], containing a ‘CoFe2S2’ core and
unstable because of the different oxidation state of Fe
atoms and different ligands on Co atom. Thus, the
unstable precursor product 4 further undergoes inner
molecular redox leading to oxidation and lose of one
brigding sulfur ion and reduction of the Feꢃ1 to Fe0,
and finally results in the stable product 2 which has a
similar core framework to M3S of Fe0-compound,
[Fe3S(CO)9]2ꢀ [26].
(nCoCÃO), 1823w (nCÃOB), 1263m (nBÃO), and 885 (nBÃC
)
cmꢀ1. X-ray crystal structure determination revealed
that this yellow brown product was Co(CO)3-
(PPh3)2BEt3 (1). In fact, the atomic emission spectrum
(AES) of 1 indicated the existence of boron. A small
amount (about 0.01 g) of bright yellow product (3) was
obtained from the filtrate, which was stayed at 4 8C for
several days. Compound 3 was characterized only by
AES and IR measurements because of its limited
quantity and lack of crystal quality suitable for X-ray
3. Experimental
3.1. Materials and methods
Acetonitrile was distilled with CaH2, MeOH and
isopropanol were dried by distillation with MgOMe.
PPh3 and Fe(CO)5 were purchased from Fluka.
Co(SCN)2 and LiBHEt3 in THF were purchased from
Aldrich. Fe2S2(CO)6 were prepared by reaction of
Fe(CO)5 with Na2S5 and KOH in MeOH [1,27].
All reaction and treatments were carried out under
nitrogen atmosphere by using Schlenk technique and all
the solvents and reagents were degassed before use.
IR spectra were recorded on Nicolet Magno 750
Fourier Transform IR Spectrometer and elemental
analysis were performed on Carlo Erba Instrumentation
Elemental Analyzer-MOD1106.
crystallography. IR (KBr) of 3: 1986s, 1930s (nCoCÃO
)
and AES measurement indicated the existence of cobalt
and absence of boron.
3.3. X-ray crystal structure determination
Crystal data and details of data collection and
refinement procedures for 1 and 2 are summarized in
Table 3. The structures were solved by conventional
direct methods and refined by the full-matrix least-
squares methods [28]. All non-hydrogen atoms were
refined anisotropically; hydrogen atoms were located at
idealized positions and refined with fixed isotropic
thermal parameters.
3.2. Synthesis of Co(CO)3(PPh3)2BEt3 (1) and
[Et4N][CoFe2(CO)8S(PPh3)] (2)
A mixture of 0.39 g (0.0015 mol) of PPh3, 0.28 g
(0.0017 mol) of Et4NCl in 20 ml of MeCN was stirred at
room temperature (r.t.) resulting in colorless solution,
then, to the solution was added 0.13 g (0.0007 mol) of
Co(SCN)2 under stirring. The reaction mixture became
blue solution (solution A). Fe2S2(CO)6 (0.25 g, 0.0007
4. Summary
A novel CoÃ
bonding, Co(CO)3(PPh3)2BEt3 (1), and a mixed-metal
S cluster compound with possible optical non-
/
B carbonyl complex with new type BÃ
/O
CoÃ
/
FeÃ
/
linearity, [Et4N][CoFe2(CO)8S(PPh3)] (2), were obtained
from the reaction of Co(CNS)2 with Fe2S2(CO)6,
mol) in 30 ml MeCN was stirred at ꢀ78 8C giving
/
orange solution and to this solution was dropped slowly
LiBEt3H and PPh3 in THFÃ
/
MeCN mixed solvents. X-

238
B. Zhuang et al. / Journal of Organometallic Chemistry 655 (2002) 233Á238
/
Table 3
Crystal data and details of data collection for 1 and 2
Director, CCDC, 12, Union Road, Cambridge CB2
1EZ, UK (Fax: ꢃ44-1223-336033; e-mail: deposit@
ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
/
Compounds
1
2
Empirical formula
Formula weight
Crystal system
Space group
C
765.49
45H45BCoO3P2
C34H35CoFe2NO8PS
819.29
Trigonal
P31
Acknowledgements
Monoclinic
P21/c (No. 14)
Unit cell dimen-
sions
We are grateful to the National Natural Science
Foundation of China (NNSFC) and State Key Labora-
tory of Structural Chemistry (SKLSC) for financial
support in this research.
˚
a (A)
11.245(3)
14.267(5)
26.076(5)
11.74(4)
11.74(4)
23.394(5)
˚
b (A)
˚
c (A)
a (8)
b (8)
g (8)
96.85(5)
120
3
˚
V (A )
Z
Dcalc (g cmꢀ3
F(000)
4154(2)
4
2793
3
References
)
1.224
1604
5.28
1.461
1260
13.56
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m(MoÁ )
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Diffractometer
/
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Enraf-Nonius CAD4 Enraf-Nonius CAD4
293(2) 293(2)
MoÁKa (0.71073 A) MoÁKa, 0.71073
0.40ꢁ0.32ꢁ0.28
2.00Á25.98
Temperature (K)
˚
Crystal size (mm3) 0.40ꢁ0.30ꢁ0.25
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/
2.38Á
/
24.98
/
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05h 513,
05k 516,
ꢀ305l 530
7625/7235
05h 512, 05k 512,
ꢀ285l 528
Reflections col-
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Data/restraints/
parameters
3787/3644
[Rintꢂ0.0807]
3644/1/434
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7235/0/469
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R1, wR2 [I ꢀ2s(I)] 0.0559, 0.1463
R1, wR2 [all data]
Goodness-of-fit
0.0267, 0.0578
0.0301, 0.0584
1.007
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/
¨
0.0735, 0.1593
1.023
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Largest difference 0.539/ꢀ0.513
0.341/ꢀ0.304
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ꢀ3
˚
peak/hole (e A
)
ray crystal structure determination revealed that 1
contained a novel BÃO bonding of which the oxygen
atom came from a metal carbonyl ligand, and 2
possessed a triangular pyramid core CoFe2S with Coꢃ
and Fe0 ions. Theoretical chemical calculation on 1 and
O bonding energy of complex 1 was
lower than that of normal covalence bonding and
compound 2 possesses a calculated nonlinear optical
/
[15] The average data are the mean of several values, and the
X)2/
estimated S.D. shown are calculated as follows: [S(Xi ꢀ
/
(Nꢀ
/
1)]1/2 where Xi is the ith value and X is the mean of N value.
2 showed that BÃ
/
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first molecular hyperpolarizability component of 28.5ꢁ
/
10ꢀ30esu. A reaction pathway involving substitution of
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desulfurization process was proposed and discussed.
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5. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC no. 178040 and 178041 for
compounds 1 and 2, respectively. Copies of this
information may be obtained free of charge from The
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¨