Reactions of (Me2C)(Me2Si)[(η5-C5H3)Mo(CO)3]2 with nitrile and subsequent cleavage of the C{triple bond, long}N bond by cooperation of molybdenum and ruthenium

Article abstract of DOI:10.1016/j.jorganchem.2007.10.026

Reaction of the doubly bridged dinuclear molybdenum complex (Me₂C)(Me₂Si)[(η⁵-C₅H₃)Mo(CO)₃]₂ (1) with benzonitrile in refluxing xylene afforded complexes (Me₂C)(Me

Full text of DOI:10.1016/j.jorganchem.2007.10.026

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Journal of Organometallic Chemistry 693 (2008) 87–96
www.elsevier.com/locate/jorganchem
Reactions of (Me2C)(Me2Si)[(g5-C5H3)Mo(CO)3]2 with nitrile
and subsequent cleavage of the C„N bond by cooperation
of molybdenum and ruthenium
*
Bin Li, Shansheng Xu, Haibin Song, Baiquan Wang
State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, People’s Republic of China
Received 12 September 2007; received in revised form 11 October 2007; accepted 16 October 2007
Available online 23 October 2007
Abstract
Reaction of the doubly bridged dinuclear molybdenum complex (Me2C)(Me2Si)[(g5-C5H3)Mo(CO)3]2 (1) with benzonitrile in reflux-
ing xylene afforded complexes (Me2C)(Me2Si)[(g5-C5H3)2Mo2(CO)4(l-g2-g2(^)-N„CPh)] (2) (50%) and (Me2C)(Me2Si)
[(g5-C5H3)2Mo2(CO)4(l-g1-g2-N„CPh)] (3) (6%) with different coordination of nitrile. The corresponding l-g2-g2 acetonitrile and pro-
pionitrile complexes 4 and 5 could be obtained from the reactions of (Me2C)(Me2Si)(C5H4)2 with (RCN)3Mo(CO)3 (R = Me, Et) in
refluxing xylene. Reactions of 1 with isonitriles generated l-g1-g2-C„NR (R = tBu, Ph, C6H11) bridged complexes 6–8 in 53–63% yields.
Subsequent reaction of 4 with Ru3(CO)12 yielded two C„N bond cleavaged MoRu clusters (Me2C)(Me2Si)(g5-C5H3)2Mo2Ru3(CO)10
(l-CO)(l3-CMe)(l4-N) (9) (7%) and [(Me2C)(Me2Si)(g5-C5H3)2]2Mo4Ru6(CO)16(l-CO)(l4-CO)2(l3-g1-g2-g2-N„CMe)(l3-CMe)
(l5-N) (10) (8%). All the new complexes have been fully characterized. The molecular structures of 2, 4, 6, 9, and 10 have been deter-
mined by X-ray diffraction analysis.
ꢀ 2007 Elsevier B.V. All rights reserved.
Keywords: Cleavage reactions; Nitrides; C„N bond activation; Heterometallic cluster compounds
1. Introduction
of the superlong Mo–Mo bond of 1, especially for the acti-
vation of unreactive bonds.
In comparison with singly bridged bis(cyclopentadienyl)
metal complexes, doubly bridged bis(cyclopentadienyl)
ligands are more rigid, locking the two metals on either
the same or opposite faces of the ligand and maintaining
the two metal centers in close proximity even after the
metal–metal bond cleavage, which could result in unique
properties in structures, reactivity and catalysis [1]. The
Me2C and Me2Si doubly bridged bis(cyclopentadienyl)
dinuclear molybdenum carbonyl complex (Me2C)(Me2-
Si)[(g5-C5H3)Mo(CO)3]2 (1) exhibited unusually long
Mo–Mo bond distances due to the rigidity of the ligand
[2]. We were, therefore, interested in the different reactivity
Nitrile is an important functional group in organic syn-
thesis, for it can be readily converted into many other
organic functional groups such as amine or amide. It is
important to prove the reactivity of a nitrile ligand with
organometallic complexes so as to elucidate the mechanism
of the reaction performed on a metal surface. Examples of
g2-coordinated nitrile for monometallic complexes are well
established (A, Chart 1) [3], but for bimetallic complexes
are very limited (B) [4,5], and there are only a few examples
of bimetallic complexes with l-g2-g2(^)-C„N coordina-
tion (C) [5]. On the other hand, the cleavage of the C„N
bond of nitrile is usually regarded as an analogue of
N„N bond activation of dinitrogen since the nitrile group
contains an sp hybridized nitrogen atom as well as dinitro-
gen [6]. In contrast to the numerous examples of carbon–
nitrogen triple bond cleavage of nitrile by way of hydration
*
Corresponding author. Tel./fax: +86 22 23504781.
E-mail address: bqwang@nankai.edu.cn (B. Wang).
0022-328X/$ - see front matter ꢀ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2007.10.026

88
B. Li et al. / Journal of Organometallic Chemistry 693 (2008) 87–96
For compound 2, mp: 183 ꢁC (dec.). Anal. Calc. for
N
C
LnM
MLn
C
LnM
MLn
LnM
C26H23Mo2NO4Si: C, 49.28; H, 3.66; N, 2.21. Found: C,
N
1
N
C
49.22; H, 3.70; N, 2.10%. H NMR (CDCl3) d 7.64 (d,
R
R
R
J = 6.15 Hz, 2H, Ph-H), 7.34 (t, 2H, Ph-H), 7.19 (t, 1H,
Ph-H), 5.60 (br s, 2H, Cp-H), 5.47 (br s, 2H, Cp-H), 5.21
(t, 2H, Cp-H), 1.65 (s, 3H, CMe), 1.37 (s, 3H, CMe),
0.65 (s, 3H, SiMe), 0.43 (s, 3H, SiMe); IR (mCO, cmꢀ1):
1981(s), 1954(s), 1914(s), 1902(s).
A
B
C
Chart 1.
in organic synthesis [7], as well as its reductive cleavage cat-
alyzed by nitrogenase enzymes [8], examples of organo-
transition metal-mediated C„N bond cleavage of nitrile
are limited to Ru [6], Ti [9], Zr [10], Mo [11], and W [12].
The cleavage of the C„C bonds of alkynes has been
observed in metal clusters with both homo- and heterome-
tallic complexes [13], or by cooperation reaction of two dif-
ferent metal complexes [13b,14]. However, there was no
report about the C„N bond cleavage of nitrile involving
reaction on a polynuclear cluster with heterometallic
framework, nor with cooperation of two different metal
complexes. In this contribution, we report the synthesis
of the l-g2-g2-nitrile complexes (Me2C)(Me2Si)
[(g5-C5H3)2Mo2(CO)4(l-g2-g2(^)-N„CR)] (R = Ph, 2;
R = Me, 4; R = Et, 5), and the further reaction of 4 with
Ru3(CO)12, which afforded two C„N bond cleavaged
For compound 3, mp: 203 ꢁC (dec.). Anal. Calc. for
C26H23Mo2NO4Si: C, 49.28; H, 3.66; N, 2.21. Found: C,
49.65; H, 3.96; N, 1.98%. H NMR (CDCl3) d 8.28 (m,
2H, Ph-H), 7.62 (m, 2H, Ph-H), 7.50 (m, 1H, Ph-H), 7.11
(m, 1H, Cp-H), 6.27 (m, 1H, Cp-H), 5.75 (m, 1H, Cp-H),
5.49 (m, 1H, Cp-H), 5.15 (m, 1H, Cp-H), 4.25 (m, 1H,
Cp-H), 1.19 (s, 6H, CMe), 0.87 (s, 3H, SiMe), ꢀ0.34 (s,
3H, SiMe); IR (mCO, cmꢀ1): 1940(s), 1859(s).
1
2.3. Synthesis of (Me2C)(Me2Si)[(g5-C5H3)2-
Mo2(CO)4(l-g2-g2(^)-N„CMe)] (4)
A solution of (Me2C)(Me2Si)(C5H4)2 (0.5 g, 2.19 mmol)
and (MeCN)3Mo(CO)3 [prepared from Mo(CO)6 (1.00 g,
3.79 mmol) in refluxing acetonitrile (10 mL) over about
6 h] [18] in xylene (50 mL) was refluxed for 15 h. After
removal of solvent the residue was chromatographed on
an alumina column using petroleum ether–CH2Cl2 as elu-
ent. The first band (red) afforded the desilylation product
(Me2C)[(g5- C5H4)Mo(CO)3]2 [19] (38 mg, 4% yield) as
deep red crystals. The second band (green) gave 1 [2]
(55 mg, 8% yield) as purple crystals. The third band
(brown-red) gave 4 (310 mg, 29% yield) as brown-red crys-
tals. For compound 4, mp: 172 ꢁC (dec.). Anal. Calc. for
C21H21Mo2NO4Si: C, 44.15; H, 3.70; N, 2.45. Found: C,
MoRu
clusters
[(Me2C)(Me2Si)(g5-C5H3)2]Mo2Ru3
(CO)10(l-CO)(l3-CMe)(l4-N) (9) and [(Me2C)(Me2Si)
(g5-C5H3)2]2Mo4Ru6(CO)16(l-CO)(l4-CO)2(l3-g1-g2-g2-
N„CMe)(l3-CMe)(l5-N) (10) in low yield. The reactions
of 1 with isonitriles were also studied for comparison.
2. Experimental
2.1. General considerations
1
44.17; H, 3.66; N, 2.44%. H NMR (CDCl3): d 5.61 (t,
Schlenk and vacuum line techniques were employed for
all manipulations. All solvents were distilled from appro-
2H, Cp-H), 5.45 (m, 2H, Cp-H), 5.17 (m, 2H, Cp-H),
2.97 (s, 3H, NCMe), 1.63 (s, 3H, CMe), 1.29 (s, 3H,
1
priate drying agents under argon prior to use. H NMR
CMe), 0.61 (s, 3H, SiMe), 0.31 (s, 3H, SiMe); IR (mCO
,
spectra were recorded on a Bruker AV300 instrument. IR
spectra were recorded as KBr disks on a Nicolet 560 ESP
FTIR spectrometer. Elemental analyses were performed
on a Perkin–Elmer 240C analyzer. Complex 1 [2] and iso-
nitriles RNC (R = tBu [15], Ph [16], C6H11 [17]) were pre-
pared by the literature methods.
cmꢀ1): 1980(s), 1944(s), 1928(s), 1909(s).
Reduction of the reaction time to 6 h afforded 4% of
(Me2C)[(g5-C5H4)Mo(CO)3]2 and increased the yield of 1
up to about 40% and decreased the yield of 4 to trace
amount.
2.4. Synthesis of (Me2C)(Me2Si)[(g5-C5H3)2Mo2-
(CO)4(l-g2-g2(^)-N„CEt)] (5)
2.2. Reaction of 1 with PhCN and synthesis of
(Me2C)(Me2Si)[(g5-C5H3)2Mo2(CO)4(l-g2-g2(^)-
N„CPh)] (2) and (Me2C)(Me2Si)[(g5-C5H3)2Mo2-
(CO)4(l-g1-g2-N„CPh)] (3)
Using a procedure similar to that described above, reac-
tion of (Me2C)(Me2Si)(C5H4)2 with (EtCN)3Mo(CO)3 gave
complex 5 as brown-red crystals in 26% yield. For com-
pound 5, mp: 156–157 ꢁC. Anal. Calc. for C22H23Mo2-
NO4Si: C, 45.14; H, 3.96; N, 2.39. Found: C, 45.25; H,
A solution of 1 (117 mg, 0.20 mmol) and PhCN
(620 mg, 6.0 mmol) in xylene (30 mL) was refluxed over-
night. After removal of solvent the residue was chromato-
graphed on an alumina column. Elution with petroleum
ether–CH2Cl2 gave a brown-red band, which afforded 2
(64 mg, 50% yield) as brown-red crystals. Elution with
CH2Cl2 developed a brown band, which afforded 3
(8 mg, 6% yield) as brown crystals.
1
3.88; N, 2.49%. H NMR (CDCl3) d 5.74 (m, 2H, Cp-H),
5.55 (m, 2H, Cp-H), 5.15 (m, 2H, Cp-H), 3.33 (s, 2H, Et-
CH2), 1.65 (s, 3H, CMe), 1.43 (m, 3H, Et-CH3), 1.27 (s,
3H, CMe), 0.64 (s, 3H, SiMe), 0.34 (s, 3H, SiMe). IR
(mCO, cmꢀ1): 1982(s), 1944(s), 1935(s), 1909(s).

B. Li et al. / Journal of Organometallic Chemistry 693 (2008) 87–96
89
2.5. Reaction of 1 with isonitrile RNC (R = tBu, Ph, C6H11)
2.6. Reaction of 4 with Ru3(CO)12
A solution of 1 (117 mg, 0.20 mmol) and tBuNC (17 mg,
0.20 mmol) in toluene (30 mL) was refluxed for 15 h. After
removal of solvent the residue was chromatographed on an
alumina column. Elution with petroleum ether–CH2Cl2
gave a green band, which afforded 6 (64 mg, 50% yield)
as green crystals as a mixture of two isomers in the ratio
7:1. For compound 6, mp: 196 ꢁC (dec.). Anal. Calc. for
C24H27Mo2NO4Si: C, 47.00; H, 4.44; N, 2.28. Found: C,
A solution of 4 (300 mg, 0.52 mmol) and Ru3(CO)12
(250 mg, 0.39 mmol) in toluene (60 mL) was refluxed for
5 h. After removal of solvent the residue was chromato-
graphed on an alumina column using petroleum ether/
CH2Cl2 as eluent. The first band (yellow) gave 68 mg of
unreacted Ru3(CO)12. The second band (green) gave 1
(102 mg, 33% yield) as purple crystals. The third band
(deep-gray) afforded 9 (21 mg, 7% yield) as deep-brown
crystals. The fourth band (brown) afforded 10 (23 mg, 8%
yield) as deep-brown crystals.
1
46.88; H, 4.25; N, 2.19%. H NMR (CDCl3) for the major
isomer: d 6.04 (m, 1H, Cp-H), 5.89 (m, 1H, Cp-H), 5.44 (m,
1H, Cp-H), 5.37 (m, 1H, Cp-H), 5.23 (m, 1H, Cp-H), 4.92
(m, 1H, Cp-H), 1.40 (s, 9H, Bu–H), 1.29 (s, 3H, CMe),
For compound 9, mp: 242 ꢁC (dec.). Anal. Calc. for
C28H21Mo2NO11Ru3Si: C, 31.41; H, 1.98; N, 1.31. Found:
C, 31.71; H, 1.80; N, 1.38%. 1H NMR (CDCl3): d 5.74 (m,
1H, Cp-H), 5.59 (m, 1H, Cp-H), 5.54 (m, 2H, Cp-H), 5.28
(m, 1H, Cp-H), 4.56 (t, 1H, Cp-H), 4.29 (s, 3H, l3-CMe),
1.96 (s, 3H, CMe), 1.71 (s, 3H, CMe), 0.60 (s, 6H, SiMe);
t
0.86 (s, 3H, CMe), 0.70 (s, 3H, SiMe), 0.53 (s, 3H, SiMe);
for the minor isomer: d 5.97 (m, 1H, Cp-H), 5.61 (m, 1H,
Cp-H), 5.47 (m, 1H, Cp-H), 5.29 (m, 2H, Cp-H), 4.85
(m, 1H, Cp-H), 1.74 (s, 3H, CMe), 1.46 (s, 3H, CMe),
1.34 (s, 9H, tBu–H), 0.36 (s, 3H, SiMe), 0.21 (s, 3H, SiMe).
IR (cmꢀ1, as mixture of isomers): mCO 1961(s), 1920(s),
1879(s), 1821(s); mCN 1716(m).
Using a procedure similar to that described above,
reactions of 1 with C6H11NC and PhNC afforded 7 (two
isomers in the ratio 5:1) and 8 (two isomers in the ratio
of 3:1) as green crystals in 58% and 63% yield,
respectively.
IR (mCO
,
cmꢀ1): 2070(s), 2050(s), 2028(s), 2004(m),
1995(m), 1979(s), 1962(s), 1912(s), 1885(s), 1855(s), 1788(s).
For compound 10. Mp: >300 ꢁC. Anal. Calc. for
C53H42Mo4N2O19Ru6Si2: C, 30.94; H, 2.06; N, 1.36.
1
Found: C, 30.88; H, 1.96; N, 1.26%. H NMR (CDCl3):
d 6.94 (m, 1H, Cp-H), 6.32 (m, 1H, Cp-H), 6.02 (m, 1H,
Cp-H), 5.96 (m, 1H, Cp-H), 5.75 (m, 1H, Cp-H), 5.71
(m, 1H, Cp-H), 5.55 (m, 1H, Cp-H), 5.53 (m, 1H, Cp-H),
5.43 (m, 1H, Cp-H), 5.40 (m, 1H, Cp-H), 5.07 (m, 1H,
Cp-H), 5.01 (m, 1H, Cp-H), 4.49 (s, 3H, l3-CMe), 3.06
(s, 3H, NCMe), 1.76 (s, 6H, CMe), 1.68 (s, 3H, CMe),
1.15 (s, 3H, CMe), 0.65 (s, 3H, SiMe), 0.33 (s, 6H, SiMe),
ꢀ0.94 (s, 3H, SiMe); IR (mCO, cmꢀ1): 2051(s), 2027(s),
1999(br s), 1968(br s), 1938(br s), 1828(m), 1491(m),
1473(m).
For compound 7, mp: 208 ꢁC (dec.). Anal. Calc. for
C26H29Mo2NO4Si: C, 48.83; H, 4.57; N, 2.19. Found: C,
1
48.60; H, 4.39; N, 2.23%. H NMR (CDCl3) for the major
isomer: d 6.01 (m, 1H, Cp-H), 5.85 (m, 1H, Cp-H), 5.45 (m,
1H, Cp-H), 5.35 (m, 1H, Cp-H), 5.24 (m, 1H, Cp-H), 4.94
(m, 1H, Cp-H), 3.48 (m, 1H, Cy-CH), 2.24–2.08 (m, 2H,
Cy-CH2), 1.87–1.75 (m, 2H, Cy-CH2), 1.72-1.63 (m, 2H,
Cy-CH2), 1.44–1.34 (m, 4H, Cy-CH2), 1.29 (s, 3H, CMe),
0.84 (s, 3H, CMe), 0.69 (s, 3H, SiMe), 0.53 (s, 3H, SiMe);
for the minor isomer: d 5.94 (m, 1H, Cp-H), 5.86 (m, 2H,
Cp-H), 5.62 (m, 1H, Cp-H), 5.29 (m, 1H, Cp-H), 4.86
(m, 1H, Cp-H), 3.45 (m, 1H, Cy-CH), 2.24–2.08 (m, 2H,
Cy-CH2), 1.87–1.75 (m, 2H, Cy-CH2), 1.73 (s, 3H, CMe),
1.72–1.63 (m, 2H, Cy-CH2), 1.45 (s, 3H, CMe), 1.44–1.34
(m, 4H, Cy-CH2), 0.35 (s, 3H, SiMe), 0.17 (s, 3H, SiMe).
IR (cmꢀ1, mixture of isomers): mCO 1972(s), 1927(s),
1875(s), 1825(s); mCN 1729(m).
2.7. Crystallographic studies
Single crystals of complexes 2, 4, 6, and 9 suitable for
X-ray diffraction were obtained from hexane/CH2Cl2,
whereas complex 10 was from hexane/CHCl3 solution.
Data collection was performed on a Bruker SMART
1000, using graphite-monochromated Mo Ka radiation
˚
(x–2h scans, k = 0.71073 A). Semiempirical absorption
corrections were applied for all complexes. The structures
were solved by direct methods and refined by full-matrix
least-squares. All calculations were using the SHELXTL-97
program system. The molecular structures of 10 contained
two CHCl3 of solvation. The crystal data and summary of
X-ray data collection are presented in Table 1.
For compound 8, mp: 191 ꢁC (dec.). Anal. Calc. for
C26H23Mo2NO4Si: C, 49.30; H, 3.66; N, 2.21. Found: C,
1
49.28; H, 3.68; N, 2.24%. H NMR (CDCl3) for the major
isomer: d 7.48-7.33 (m, 5H, Ph-H), 6.19 (m, 1H, Cp-H),
5.94 (m, 1H, Cp-H), 5.57 (m, 1H, Cp-H), 5.40 (m, 1H,
Cp-H), 5.36 (m, 1H, Cp-H), 5.06 (m, 1H, Cp-H), 1.28
(s, 3H, CMe), 0.74 (s, 3H, CMe), 0.65 (s, 3H, SiMe),
0.58 (s, 3H, SiMe); for the minor isomer: d 7.19–7.14
(m, 5H, Ph-H), 6.02 (m, 2H, Cp-H), 5.81 (m, 1H, Cp-
H), 5.53 (m, 1H, Cp-H), 5.41 (m, 1H, Cp-H), 4.98 (m,
1H, Cp-H), 1.79 (s, 3H, CMe), 1.50 (s, 3H, CMe), 0.32
(s, 3H, SiMe), ꢀ0.11 (s, 3H, SiMe). IR (cmꢀ1, as mixture
of isomers): mCO1967(s), 1920(s), 1879(s), 1831(s); mCN
1680(s).
3. Results and discussion
3.1. Reaction of (Me2C)(Me2Si)[(g5-C5H3)Mo(CO)3]2
(1) with nitrile and isonitrile
Reaction of 1 with PhCN in refluxing xylene afforded
the perpendicularly coordinated benzonitrile complex

90
B. Li et al. / Journal of Organometallic Chemistry 693 (2008) 87–96
Table 1
Summary of crystallographic data for 2, 4, 6, 9, and 10 Æ 2CHCl3
2
4
6
9
10 Æ 2CHCl3
Empirical formula
Fw
Crystal system
Space group
C26H23Mo2NO4Si C21H21Mo2NO4Si C24H27Mo2NO4Si C28H21Mo2NO11Ru3Si C55H44Cl6Mo4N2O19Ru6Si2
633.42
Orthorhombic
P212121
11.1918(19)
12.724(2)
17.095(3)
90
571.36
Monoclinic
P21/c
10.308(3)
10.613(3)
19.737(6)
90
613.44
Monoclinic
P2(1)/c
10.694(3)
13.962(3)
17.436(4)
90
1070.64
Orthorhombic
P212121
10.666(3)
16.159(4)
18.690(5)
90
2295.98
Monoclinic
P21/c
15.500(3)
19.356(3)
23.100(4)
90
˚
a (A)
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
90
90
96.608(5)
90
104.099(4)
90
90
90
92.952(3)
90
3
˚
V (A )
2434.4(7)
4
2144.7(11)
4
2525.0(10)
4
3221.2(14)
4
6921(2)
4
Z
Dcalc (g cmꢀ3
)
1.728
1.769
1.614
2.208
2.203
l (mmꢀ1
F(000)
)
1.113
1.252
1.070
2.228
2.303
1264
1136
1232
2056
4408
Crystal size (mm)
Maximum 2h (ꢁ)
0.24 · 0.20 · 0.18 0.30 · 0.20 · 0.06 0.28 · 0.22 · 0.18 0.34 · 0.32 · 0.28
0.24 · 0.20 · 0.16
50.02
52.72
52.84
52.94
54.34
No. of reflections collected
14149
12115
13937
18299
34959
No. of independent reflections/Rint 4963/0.0245
4380/0.0305
267
1.048
0.0259, 0.0565
0.0407, 0.0628
5186/0.0466
296
1.004
0.0330, 0.0572
0.0745, 0.0688
7067/0.0268
420
1.093
0.0256, 0.0472
0.0359, 0.0506
12204/0.0797
857
1.017
0.0461, 0.0990
0.0944, 0.1197
2.222 and ꢀ0.971
No. of parameters
Goodness-of-fit on F2
R1, wR2 [I > 2r(I)]
R1, wR2 (all data)
311
1.033
0.0209, 0.0465
0.0252, 0.0483
Largest difference in peak and hole 0.450 and ꢀ0.196 0.584 and ꢀ0.281 0.524 and ꢀ0.522 0.535 and ꢀ0.562
ꢀ3
˚
(e A
)
(Me2C)(Me2Si)[(g5-C5H3)2Mo2(CO)4(l-g2-g2(^)-N„CPh)]
(2) and the r + p coordinated benzonitrile complex
(Me2C)(Me2Si)[(g5-C5H3)2Mo2(CO)4(l-g1-g2-N„CPh)] (3)
(Scheme 1). The interconversion of the isomeric complexes
2 and 3 was not detected by heating 2 or 3 in refluxing
xylene separately. The reaction of 1 with CH3CN in reflux-
ing xylene only afforded the corresponding acetonitrile
complex 4 in very poor yield. However, complex 4 was iso-
lated in 29% yield together with the desilylation product
(Me2C)[(g5-C5H4)Mo(CO)3]2 (4%) [19] and 1 (8%) [2] from
the reaction of the doubly bridged ligand (Me2C)(Me2-
Si)(C5H4)2 with (MeCN)3Mo(CO)3 in refluxing xylene for
15h (Scheme 2). Reduction of the reaction time to 6 h
increased the yield of 1 up to about 40% but decreased
the yield of 4 to trace amount. The propionitrile complex
5 was synthesized using similar procedure. It is not clear
why nitriles with lower boiling points such as acetonitrile
and propionitrile react with 1 only produce trace 4 and 5.
It should also note that other nitriles such as PhCH2CN
and EtO2CCH2CN do not react with complex 1. The rea-
Me2
C
Me2
C
Me2
Si
Me2
C
Mo
Mo
Mo
Mo
+
(CO)3 (CO)3 (CO)3 (CO)3
Me2
Si
(4%) 1 (8%)
xylene
reflux
+
Me2
C
(RCN)3Mo(CO)3
Me2
Si
Mo
Mo(CO)2
(CO)2
+
N
C
R
R = Me
Et
4 (29%)
5 (26%)
Scheme 2.
and 5 show resonances which can be assigned to equivalent
Cp rings, the bridging CMe2 and SiMe2 groups and the R
groups of the nitrile ligands.
The molecular structure of 2 was determined by single
crystal X-ray diffraction analysis (Fig. 1). An important
feature of 2 is the l-g2-g2-N„CPh bridging ligand, which
is perpendicular to the Mo–Mo bond. This is in contrast to
the result of the reaction of the non-bridged dimolybdenum
complex Cp2Mo2(CO)6 with cyanamide R2NCN (R = H,
Me), which only produced the l-g1-g2-C„N adduct [4a].
This is probably due to the rigidity of the doubly bridged
bis(cyclopentadienyl) ligand, which might be in favor of
the crosswise-bridging l-g2-g2(^)-C„N coordination. The
crosswise coordination significantly increases the C–N
1
son is still not clear, either. The H NMR spectra of 2, 4,
Me2
C
Me2
C
Me2
Me2
Si
Si
C6H5CN
xylene
Mo
Mo
Mo
Mo
OC
CO OC
CO
CO
Ph
3 (6%)
+
1
OC
CO
C
OC
N
N
C
Ph
2 (50%)
˚
Scheme 1.
bond distance to 1.299(3) A and decreases the N–C–Me

B. Li et al. / Journal of Organometallic Chemistry 693 (2008) 87–96
91
Fig. 2. ORTEP diagram of complex (Me2C)(Me2Si)[(g5-C5H3)2Mo2
(CO)4(l-g2-g2(^)-N„CMe)] (4). Thermal ellipsoids are shown at the
˚
30% level. Selected bond lengths [A] and angles [ꢁ] are Mo(1)–Mo(2)
Fig. 1. ORTEP diagram of complex (Me2C)(Me2Si)[(g5-C5H3)2Mo2
(CO)4(l-g2-g2(^)-N„CPh)] (2). Thermal ellipsoids are shown at the
30% level. Selected bond lengths [A] and angles [ꢁ] are Mo(1)–Mo(2)
2.8993(5), Mo(1)–N(1) 2.151(2), Mo(2)–N(1) 2.138(3), Mo(1)–C(5)
2.196(3), Mo(2)–C(5) 2.190(3), C(5)–N(1) 1.299(3), Mo(1)–N(1)–Mo(2)
85.06(8), Mo(1)–C(5)–Mo(2) 82.76(9), N(1)–C(5)–C(6) 131.7(3), Cp–Cp
fold angle 134.4, Cp(centroid)–Mo(1)–Mo(2)–Cp(centroid) 8.2.
2.9180(9), Mo(1)–N(1) 2.147(2), Mo(2)–N(1) 2.175(3), Mo(1)–C(5)
2.199(3), Mo(2)–C(5) 2.184(3), C(5)–N(1) 1.284(4), Mo(1)–N(1)–Mo(2)
84.93(9), Mo(1)–C(5)–Mo(2) 83.47(10), N(1)–C(5)–C(6) 134.6(3), Cp–Cp
fold angle 136.3, Cp(centroid)–Mo(1)–Mo(2)–Cp(centroid) 5.9.
˚
Cp proton at d 7.11 ppm and for a Si–Me protons at d
ꢀ0.34 ppm are significantly downfield or upfield from the
typical Cp (d 4-6 ppm) and Si–Me (d 0–1 ppm) proton
region, respectively, due to the deshielding or shielding
effect of the bridging N„CPh ligand.
angle to 131.7(3)ꢁ, consistent with the absence of C„N
stretching absorption. Complex 4 has similar structure and
its molecular structure is depicted in Fig. 2. In Table 2 the
dimensions of core (l-g2-g2-RCN)Mo2 units in complexes
2, 4, [Mo2(l-g2-NCCH3) (l-NC(CH3)PPh2CH2 CH2PPh2)
(NCCH3)7](BF4)4 (I) [5a], [Mo2(l-g2-NCCH3) (l-PPh2-
NHPPh2) (l-NC(CH3)PPh2)NPPh2(NCCH3)5] (BF4)3 (II)
[5b], [Mo2(l-g2-NCCH3)(l-O)(l-PPh2NHPPh2) (NCCH3)4]-
(BF4)2 (III) [5b], and the corresponding (l-g2-g2-CH3CN)
W2 unit in W2Cl4(l-PPh2CH2PPh2)2(l-g2-NCCH3) (IV)
[5c] are collected for comparison. All the bridging nitrile
ligands are no longer linear and greatly bended. The N–C–
C(R) angles in III and IV [117.7(5)ꢁ, 116.7(3)ꢁ] are close to
the ideal value for sp2-hybridized atoms, while those in the
former four compounds are significantly large (131–136ꢁ).
Although the isostructural and isoelectronic alkyne com-
plexes are well studied [20], the nitrile complexes of this kind
are still uncommon [5].
Complex 3 is stable in solid state but somewhat air sen-
sitive in solution, which were initially characterized spec-
troscopically. The IR bands at 1940 and 1859 cmꢀ1 are
assigned to the carbonyl ligands; the bridging g1-g2-
N„CPh stretching vibration is at 1639 cmꢀ1, similar to
that of Cp2Mo2(CO)4(l-g1-g2-N„CPh) [4a]. Its 1H
NMR spectrum exhibits inequivalent resonances for the
Cp protons, suggesting the unsymmetrical bonding of ben-
zonitrile to the dimolybdenum moiety. The signals for one
Since the reactions of 1 with nitriles do not parallel with
those of non-bridged complex Cp2Mo2(CO)6, we then
choose isonitriles, which also have C„N bonds, as sub-
strates to react with 1. When 1 reacted with equimolar of
isonitriles in refluxing toluene, complexes (Me2C)(Me2-
Si)[(g5-C5H3)2Mo2(CO)4(l-g1-g2-C„NR)] (R = tBu, 6;
R = Ph, 7; R = C6H11, 8) were obtained in good yield
(Scheme 3). This is consistent with the result of the reaction
of Cp2Mo2(CO)6 with isonitriles [21]. The 1H NMR spectra
of 6–8 exhibit inequivalent resonances for the protons of
Cp rings, the R group of isonitriles, and the CMe2 and
1
SiMe2 groups. The H NMR spectra also show the exis-
tence of another minor isomer (see Section 2). In the major
isomers, one of the signal (d = 0.86, 0.74, and 0.84 ppm for
6, 7, and 8, respectively) is approximately 0.4 ppm upfield
from the typical CMe2 region due to the shielding effect
of the bridging isonitrile ligand. Their IR spectra display
four strong terminal carbonyl absorptions and a low-
energy absorption for the l-g1-g2-C„NtBu ligand at
1716, 1680, and 1729 cmꢀ1 for 6, 7, and 8, respectively.
Details of the molecular structure of one isomer of 6
were established by an X-ray crystallographic analysis
(Fig. 3). The dimension of Mo2(CO)4(l-g1-g2-C„NtBu)
core structure in 6 is similar to that of the analogues
Cp2Mo2(CO)4(l-g1-g2-C„NR) (R = Me [21a], tBu

92
B. Li et al. / Journal of Organometallic Chemistry 693 (2008) 87–96
Table 2
a
˚
Comparison of selected bond distances (A) and angles (ꢁ) of 2, 4, I, II, III, and IV
2
4
I
II
III
1.34(1)
1.47(1)
117.7(5)
69.7(2)
IV
1.303(8)
1.617(11)
116.7(3)
72.9(2)
72.8(2)
N–C
1.299(3)
1.466(4)
1.284(4)
1.504(4)
1.269(8)
1.514(9)
1.27(1)
1.49(2)
C–C(R)
N–C–C(R)
M–N–M
M–C–M
131.7(3)
85.06(8)
82.76(9)
134.6(3)
84.93(9)
83.47(10)
136.2(6)
72.0(2)
72.8(2)
134.6(10)
70.7(2)
72.4(3)
69.7(2)
aI: Mo2(l-g2-NCCH3)(l-NC(CH3)PPh2CH2CH2PPh2) (NCCH3)7](BF4)4 [5a].
II: Mo2(l-g2-NCCH3)(l-PPh2NHPPh2)(l-NC(CH3)PPh2)NPPh2(NCCH3)5](BF4)3 [5b].
III: [Mo2(l-g2-NCCH3)(l-O)(l-PPh2NHPPh2)(NCCH3)4](BF4)2 [5b].
IV: W2Cl4(l-PPh2CH2PPh2)2(l-g2-NCCH3) [5c].
Me2
C
Me2
Si
RNC
Mo
Mo
OC
OC
CO
CO
1
toluene
C
N
R
R = tBu
C6H11
Ph
6 (53%)
7 (63%)
8 (58%)
Scheme 3.
[21c]). The bimetallic system is bridged by the CNtBu
ligand coordinated in a r + p fashion: with isocyano car-
˚
bon C(5) r bonded to Mo(1) [Mo(1)–C(5) = 1.946(4) A],
while C–N function
C(5) = 2.282(3) A, Mo(2)–N(1) = 2.224(3) A]. The intro-
duction of the isonitrile bridging ligand decreases the
p bonded to Mo(2) [Mo(2)–
˚
˚
˚
Mo–Mo bond distance to 3.2109(6) A, compared to that
˚
of 1 (3.4328(12) A). The long C(5)–N(1) bond length of
˚
1.226(4) A agrees with the low-energy absorption in its
Fig. 3. ORTEP diagram of complex (Me2C)(Me2Si)[(g5-C5H3)2Mo2
(CO)4(l-g1-g2-N„CtBu)] (6). Thermal ellipsoids are shown at the 30%
level. Selected bond lengths [A] and angles [ꢁ] are Mo(1)–Mo(2) 3.2109(6),
Mo(1)–C(5) 1.946(4), Mo(2)–C(5) 2.282(3), Mo(2)–N(1) 2.224(3), Mo(1)–
C(5)–N(1) 169.4(3), C(5)–N(1)–C(6) 135.8(3), Mo(1)–C(5)–Mo(2)
98.54(15), Cp–Cp fold angle 143.4, Cp(centroid)–Mo(1)–Mo(2)–Cp(cen-
troid) 0.1.
IR spectrum. The major and minor isomers of the product
are obtained as unseparable mixtures and they are not
interconvertible in solutions. The amount of the single
crystal is not enough to verify that the X-ray analysis for
6 has been done is for the major or minor isomer. Due to
the difference of the two bridging atoms, the two isomers
can be assumed as the structures with exchanging the loca-
tion of CMe2 and SiMe2 group in the doubly bridged
ligand.
˚
(7% and 8%, respectively) along with 1 (33%) (Scheme 4).
It is evident that the formation of the l4-, l5-nitrido and
l3-CMe ligands in complexes 9 and 10 must result from
the C„N bond rupture of acetonitrile. Further reaction
of 9 with 4 and Ru3(CO)12 did not generate 10. A number
of metal clusters containing l4-N and l5-N ligands have
been studied by X-ray diffraction [23–26]. But none of
the l4- and l5-nitrido atoms in these complexes derived
from C„N bond cleavage of nitrile. In contrast to a few
illustrations of C„N bond cleavage to form metal nitride
[6,11,12], this is, to the best of our knowledge, the first
example that C„N bond ruptured to construct the l4-nitr-
ido and l5-nitrido ligands in a heterometallic system.
3.2. Reaction of 4 with Ru3(CO)12
Morris and co-workers demonstrated that the thermal
reactions of the dimolybdenum alkyne complexes
Cp2Mo2(CO)4(l-g2-g2-R1C„CR2) with Ru3(CO)12 led to
the C„C bond cleavage of alkynes [22]. So the reaction
of 4 with Ru3(CO)12 in refluxing toluene was done, and
two nitrido clusters [(Me2C)(Me2Si)(g5-C5H3)2]Mo2Ru3
(CO)10(l-CO)(l3-CMe)(l4-N) (9) and [(Me2C)(Me2Si)
(g5-C5H3)2]2Mo4Ru6(CO)16(l-CO)(l4-CO)2(l3-g1-g2-g2-
N„CMe)(l3-CMe)(l5-N) (10) were isolated in low yields

B. Li et al. / Journal of Organometallic Chemistry 693 (2008) 87–96
93
Me2
C
Me2
Si
Me
C
Ru3(CO)12
toluene
Mo(CO)2
Ru
Mo
C
O
1
4
+
N
(33%)
Ru
Ru
(CO)3
(CO)2 (CO)3
9 (7%)
(CO)3
Ru
(CO)2
Ru
C
Mo
Mo
O
(CO)2 OC
Mo
CO
N
N
C
Ru
Ru
OC
Me
C
2
Si
Me2
Me
2Si
C
Me2
+
Ru
OC
O
Mo
(CO)2
C
Me
CO
CO
C
Ru
(CO)2
Me
10 (8%)
Scheme 4.
Fig. 4. ORTEP diagram of complex [(Me2C)(Me2Si)(g5-C5H3)2]Mo2R-
u3(CO)10(l-CO)(l3-CMe)(l4-N) (9). Thermal ellipsoids are shown at the
30% level. Selected bond lengths [A] and angles [ꢁ] are Mo(1)–Mo(2)
Both 9 and 10 are air stable crystals, but in solution they
are somewhat air sensitive. The H NMR spectrum of 9
1
˚
shows five groups of peaks for the Cp protons, three
groups of peaks for the bridging CMe2 and SiMe2 protons,
and a singlet at d 4.29 ppm for the ethylidyne ligand. The
signal of the ethylidyne is similar to that for Cp2Mo2Ru4-
(CO)12(l3-CMe) [22a], but significantly downfield relative
3.0014(8), Mo(1)–Ru(1) 2.8505(7), Mo(1)–Ru(2) 2.8203(8), Mo(2)–Ru(2)
2.7242(7), Mo(2)–Ru(3) 2.7943(8), Ru(1)–Ru(2) 2.7803(8), Ru(2)–Ru(3)
2.7426(7), Mo(1)–N(1) 2.073(3), Mo(2)–N(1) 1.934(3), Ru(1)–N(1)
1.961(3), Ru(2)–N(1) 2.117(3), Mo(2)–C(12) 1.995(4), Ru(2)–C(12)
2.162(5), Ru(3)–C(12) 2.107(4), Mo(2)–N(1)–Ru(2) 84.41(13), Ru(1)–
N(1)–Ru(2) 85.87(13), Mo(1)–N(1)–Ru(2) 84.61(13), Mo(1)–N(1)–Mo(2)
96.96(14), Ru(1)–N(1)–Mo(1) 89.86(13), Mo(2)–N(1)–Ru(1) 167.54(19),
Mo(2)–C(12)–Ru(3) 85.82(16), Mo(2)–C(12)–Ru(2) 81.77(16), Ru(2)–
C(12)–Ru(3) 79.92(15), Cp–Cp fold angle 138.0, Cp(centroid)–Mo(1)–
Mo(2)–Cp(centroid) 13.7.
1
to the signal of the g2-g2-N„CMe in 4. The H NMR
spectrum of 10 is composed of twelve groups of peaks
for the Cp protons, two singlets at d 4.49 and 3.06 ppm
for the l3-CMe and g2-g2-N„CMe protons, respectively,
and six groups of peaks for the bridging CMe2 and SiMe2
protons with one of the SiMe2 protons significantly upfield
to ꢀ0.94 ppm. This reveals that two molecules of 4 are
incorporated in 10. In IR spectra 9 displays eleven absorp-
tions for both terminal and bridging carbonyls, whereas 10
exhibits eight absorptions for terminal, bridging carbonyls
and the quadruply bridging (l4) carbonyl ligands.
˚
C(12) = 2.107(4) A], and their lengths are comparable to
those found for Cp2Mo2Ru4(CO)12(l3-CMe)2 [22a]. One of
the eleven carbonyl groups, C(3)–O(3), bridges Mo(2)–
Ru(3) bond. The others are all linear terminal carbonyl
ligands except C(2)–O(2) and C(8)–O(8), which adopts a
weak semi-bridging coordination to the Mo(1)–Mo(2) and
Ru(2)–Ru(1) bonds, respectively [\Mo(1)–C(2)–C(2)
166.7(4)ꢁ, \Ru(2)–C(8)–C(8) 169.5(4)ꢁ] [28]. All the arrange-
ments of carbonyl ligands are in good agreement with its IR
spectrum. In the case that l4-N ligand is a five electron
donor, 9 has a total 76 cluster valence electrons. So the clus-
ter obeys both the Wade-Mingos rules [29] and the 18-elec-
tron rule.
Cluster 10 has a tetrahedral Mo2–nitrile [Mo(1)–Mo(2)]
structure unit, namely, one molecule of 4 linked to a
Mo2Ru6–l5-nitrido [Mo(3)–Mo(4)] moiety via N(1)–Ru(1)
dative bond. Since the g2-g2(^)-nitrile ligand of 4 acts as a
four-electron donor to the dimolybdenum centers, it can still
coordinate to Ru(1) atom with its lone-pair electron in a k-N
fashion [30]. The unique geometry of Mo2Ru6–l5-nitrido
moiety can be described as a distorted bicapped [Ru(3)
and Ru(6)] square pyramid [l5-nitrido-Mo2Ru3] with a
‘‘spiked’’ atom Ru(1) attached to the apical ruthenium atom
Since neither the NMR nor the IR spectra on 9 and 10
were structurally definitive, the single crystal X-ray diffrac-
tion studies were carried out which revealed the structures
shown in Figs. 4 and 5, respectively. The metal framework
of 9 consists of a Mo2Ru2 butterfly fragment with an addi-
tional Ru(3) atom spanning one of the Mo–Ru bonds. The
nitrido ligand is semi-encapsulated within the Mo2Ru2 but-
terfly moiety and the ethylidyne ligand caps the MoRu2 tri-
angular face. This metal framework geometry bears a
striking resemblance to that of CpꢁMo3Co2ðCOÞ
3
8
ðl3-NHÞðl4-NÞ except the difference of the butterfly hinge
position [24d]. The Mo–Ru and Ru–Ru bond distances of
cluster 9 are comparable to or a little shorter than those
found in other Mo–Ru clusters [22,27]. The N–Mo [24d]
and N–Ru [24b,24c–26] bond lengths are similar to those
found for l4-N clusters. The l3-alkylidyne carbon C(12),
caps the triangle somewhat unsymmetrically [Mo(2)–
˚
˚
C(12) = 1.995(4) A, Ru(2)–C(12) = 2.162(5) A, Ru(3)–

94
B. Li et al. / Journal of Organometallic Chemistry 693 (2008) 87–96
Fig. 5. Molecular structure of [(Me2C)(Me2Si)(g5-C5H3)2]2Mo4Ru6(CO)16(l-CO)(l4-CO)2(l3-g1-g2-g2-N„CMe)(l3-CMe)(l5-N) (10). The left drawing
shows the whole molecular structure. The right drawing depicts the architecture of the Mo2Ru6(CO)13(l-CO)(l4-CO)2(l3-CMe)(N)(l5-N) core. Selected
˚
bond lengths [A] and angles [ꢁ] are Mo(1)–Mo(2) 2.8695(11), Mo(3)–Mo(4) 3.0250(10), Ru(1)–Ru(2) 2.8214(10), Ru(2)–Ru(3) 2.6561(9), Ru(2)–Ru(4)
2.8753(10), Ru(2)–Ru(5) 2.7677(10), Ru(2)–Ru(6) 2.7683(10), Ru(2)–Mo(3) 2.7993(11), Ru(2)–Mo(4) 2.6627(10), Ru(3)–Ru(4) 3.0457(11), Ru(3)–Mo(3)
2.7988(11), Ru(4)–Ru(5) 2.8244(10), Ru(4)–Mo(3) 2.8364(12), Ru(5)–Ru(6) 2.8070(11), Ru(5)–Mo(4) 2.9305(12), Ru(6)–Mo(4) 2.7545(11), C(21)–N(1)
1.319(9), Ru(1)–N(1) 2.178(6), Ru(1)–O(8) 2.129(6), Ru(1)–C(8) 2.550(8), Ru(1)–O(9) 2.153(5), Ru(2)–C(8) 2.448(8), Ru(2)–C(9) 2.129(7), Ru(3)–C(8)
2.223(8), Ru(3)–C(23) 2.124(9), Ru(4)–C(23) 2.124(9), Ru(6)–C(9) 2.357(8), Mo(3)–C(23) 2.115(8), Mo(3)–C(8) 1.949(9), Mo(4)–C(9) 1.988(8), C(8)–O(8)
1.233(9), C(9)–O(9) 1.226(9), N(2)–Ru(2) 2.048(6), N(2)–Ru(4) 2.082(6), N(2)–Ru(5) 2.081(7), N(2)–Mo(4) 1.980(6), N(2)–Mo(3) 2.112(7), Mo(1)–N(1)–
Mo(2) 83.0(2), Mo(1)–C(21)–Mo(2) 83.7(3), N(1)–C(21)–C(22) 131.1(8), C(21)–N(1)–Ru(1) 125.0(5), Ru(2)–N(2)–Ru(4) 88.2(2), Ru(2)–N(2)–Ru(5)
84.2(2), Ru(2)–N(2)–Mo(3) 84.6(2), Ru(2)–N(2)–Mo(4) 82.7(2), Ru(4)–N(2)–Mo(3) 85.1(2), Ru(5)–N(2)–Mo(4) 92.3(3), Mo(3)–N(2)–Mo(4) 95.3(3),
Ru(4)–N(2)–Ru(5) 85.4(3), Cp1–Cp2 fold angle 136.7, Cp3–Cp4 fold angle 139.0, Cp(centroid)–Mo(1)–Mo(2)–Cp(centroid) 3.4, Cp(centroid)–Mo(3)–
Mo(4)–Cp(centroid) 3.1.
˚
Ru(2). The l5-nitride nitrogen N(2) lies 0.1866 A below the
basal Mo2Ru2 plane of the square pyramid. The ethylidyne
ligand l3-MeC(23) caps a MoRu2 triangular face [Mo(3)R-
u(3)Ru(4)], which is analogous to that of 9. The N–M bond
lengths are also comparable to those of 9 and other l5-N
complex [24d,24i,26b]. Both the Mo–Ru and Ru–Ru bond
distances span a wide range, which are 2.6627(10)–
In conclusion, reactions of the doubly bridged bis(cyclo-
pentadienyl) dinuclear molybdenum complex (Me2C)(Me2-
Si)[(g5-C5H3)Mo(CO)3]2 (1) with nitrile mainly gave the
perpendicularly coordinated nitrile complex (Me2C)(Me2-
Si)[(g5-C5H3)2Mo2(CO)4(l-g2-g2(^)-N„CR)]. This is in
contrast to the reaction of the non-bridged dimolybdenum
complex Cp2Mo2(CO)6 with cyanamide R2NCN, which
only produced the l-g1-g2-C„N adduct. This indicated
that the rigidity of the doubly bridged bis(cyclopentadie-
nyl) ligand might be in favor of the crosswise l-g2-g2(^)-
C„N coordination. Two MoRu clusters containing a l4
and a l5-N ligand, respectively, were obtained via the
C„N bond cleavage of acetonitrile by cooperation of the
dimolybdenum complex and Ru3(CO)12.
˚
2.9305(12) and 2.6561(9)–3.0457(11) A, respectively.
Another feature of 10 is the two l4-carbonyl ligands C(8)–
O(8) and C(9)–O(9) [31]. The C–O bond lengths are consid-
erably longer than the terminal C–O bonds [1.233(9) and
˚
˚
1.226(9) A vs. av. 1.136 A], indicating a significant reduction
in CO bond order. This is also supported by its very low IR
absorptions at 1491 and 1473 cmꢀ1. Besides C(15)–O(15) is
a bridging carbonyl, the others are all terminal in the
remaining 17 carbonyl ligands. Assuming that bridging
nitrile and l5-nitride ligands act as 6e and 5e donors, respec-
tively, 10 contains 148 cluster valence electrons. Sixteen
metal–metal bonds in 10 would be expected by the 18-elec-
tron rule, and this is observed.
4. Supplementary material
CCDC 636559, 636560, 636561, 636562 and 660007 con-
tain the supplementary crystallographic data for 2, 4, 9, 10,
and 6. These data can be obtained free of charge from The

B. Li et al. / Journal of Organometallic Chemistry 693 (2008) 87–96
95
(b) M. Kobayashi, M. Goda, S. Shimizu, Biochem. Biophys. Res.
Commun. 253 (1998) 662, and references cited therein.
[9] (a) K.M. Doxsee, J.K.M. Mouser, Organometallics 9 (1990) 3012;
(b) Z. Xi, K. Sato, Y. Gao, J. Lu, T. Takahashi, J. Am. Chem. Soc.
125 (2003) 9568.
Cambridge Crystallographic Data Centre via www.ccdc.
cam.ac.uk/data_request/cif.
Acknowledgements
[10] X. Sun, C. Wang, Z. Li, S. Zhang, Z. Xi, J. Am. Chem. Soc. 126
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[11] (a) D.E. Coons, J.C.V. Laurie, R.C. Haltiwanger, M. Rakowski
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This work was financially supported by NSFC (Grants
20421202, 20472034, 20702026), Specialized Research
Fund for the Doctoral Program of Higher Education
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