Novel stable five-coordinate diorgano cobalt(III) complexes: Formation, structure, and reaction with carbon monoxide

Article abstract of DOI:10.1016/j.ica.2006.03.029

A series of new five-coordinate acyl vinyl cobalt(III) complexes Co{η¹-C(C{triple bond, long}CPh){double bond, long}CHPh}[C(O){single bond}C{double bond, long}C{single bond}O] L₂(L = PMe₃) (6-10) were prepared via formal insertion of diphenylbutadiyne into Co-H function of mer-octahedral hydrido-acyl(phenolato)-cobalt(III) complexes. The complexes are diamagnetic. One square pyramidal structure of complex 6 was confirmed by X-ray diffraction analysis. These complexes are stable in solid state. In solution, six-coordinate acyl vinyl carbonyl cobalt(III) complex 11 is approved through the reaction of complex 7 with CO and the structure of complex 11 was determined by X-ray method.

Full text of DOI:10.1016/j.ica.2006.03.029

Inorganica Chimica Acta 359 (2006) 3117–3122
www.elsevier.com/locate/ica
Novel stable five-coordinate diorgano cobalt(III)
complexes: Formation, structure, and reaction with carbon monoxide
a,
a
a
b
Xiaoyan Li *, Fengli Yu , Hongjian Sun , Haoqing Hou
a
School of Chemistry and Chemical Engineering, Shandong University, Shanda Nanlu 27, 250100 Jinan, PR China
College of Chemistry and Chemical Engineering, Jiangxi Normal University, Beijing Xilu 437, 330027 Nanchang, PR China
b
Received 1 September 2005; received in revised form 21 March 2006; accepted 24 March 2006
Available online 3 April 2006
Abstract
A series of new five-coordinate acyl vinyl cobalt(III) complexes Co{g1-C(C„CPh)@CHPh}[C(O)AC@CAO] L2(L = PMe3) (6–10)
were prepared via formal insertion of diphenylbutadiyne into Co–H function of mer-octahedral hydrido-acyl(phenolato)-cobalt(III)
complexes. The complexes are diamagnetic. One square pyramidal structure of complex 6 was confirmed by X-ray diffraction analysis.
These complexes are stable in solid state. In solution, six-coordinate acyl vinyl carbonyl cobalt(III) complex 11 is approved through the
reaction of complex 7 with CO and the structure of complex 11 was determined by X-ray method.
ꢀ 2006 Elsevier B.V. All rights reserved.
Keywords: Five-coordinate; Cobalt complex; Trimethylphosphine; Diphenylbutadiyne
1. Introduction
cobalt(III) complexes have been structurally characterized
[4,6].
Transition metal hydride complexes react with diyne to
provide unsaturated r-(alkynyl)vinyl derivatives by mono-
insertion of the alkyne into the M–H bond accompanying
one ligand leaving [1–3]. Presently, such reactions mainly
center on ruthenium complexes. For example, a ruthenium
hydride complex RuClH(CO)(PPh3)3 reacts with disubsti-
We have recently reported some insertion reactions of
trimethylphosphine-supported
hydrido(acyl)enolatoco-
balt(III) complexes with phenylethine, trimethylsilylethine,
bis(trimethylsilyl)butadiyne [7] and propynoic acid ethyl
ester [8]. Products of these reactions are five-coordinate
cobalt(III) complexes. One square pyramid structure was
confirmed by X-ray diffraction analysis [8].
t
tuted butadiyne RC„CC„CR (R = SiMe3, Ph, Bu) at
room temperature, giving the five-coordinatively unsatu-
rated complexes Ru{g1-C(C„CR)@CHR}Cl(CO)(PPh3)2.
The highly unsaturated vinyl ligand may also coordinate as
three-electron donor becoming g3-butadienyl ligand [3].
Five-coordinate cobalt(III) complexes are not saturated
coordination compounds and have significance for cata-
lytic chemistry due to potential application as catalyst.
Some examples of five-coordinate alkyl cobalt(III) macro-
cycle compounds are known. Most of them were synthe-
sized as model compounds for vitamin B12 [4] as well as
for cobalamins [5]. But so far few of five-coordinate
In order to study the regioselectivity of insertion reac-
tion with different alkynes, in this paper we present some
new insertion reactions of 2-acyl enolato and phenolato
hydrido cobalt(III) complexes with diphenylbutadiyne.
2. Experimental
2.1. General procedures and materials
Standard vacuum techniques were used in manipula-
tions of volatile and air-sensitive material. The solvents
were dried by known procedures and used freshly distilled.
Melting points/decomposition temperatures: sealed
capillaries, uncorrected values. Literature methods were
*
Corresponding author. Tel.: +86 53188361350; fax: +86 53188564464.
E-mail address: xli63@sdu.edu.cn (X. Li).
0020-1693/$ - see front matter ꢀ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2006.03.029

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X. Li et al. / Inorganica Chimica Acta 359 (2006) 3117–3122
1
applied in the preparation of complexes 1–5 [9]. Diph-
enylbutadiyne was obtained by the literature method [10].
The other chemicals were used as purchased. IR: Nujol
mulls between KBr discs, Bruker spectrophotometer type
VECTOR 22. 1H, 13C and 31P NMR spectra (400, 100
and 162 MHz, respectively) were recorded with a Brucker
AV 400 MHz spectrometer. 13C and 31P NMR resonances
were obtained with broad-band proton decoupling. C, H
analyses were carried out in a German ELEMENTAR
Vario ELIII analyzer. Single-crystal structures were deter-
mined with Bruker AXS P4 diffractometer.
(C@O); 1590, 1568, 1520 (C@C) cmꢀ1. H NMR (CDCl3,
300 K): d = 1.14 (s, 18H, PCH3), 6.92 (s, 1H, C@CH),
6.94–7.60 (m, 20H, CH) ppm. 13C NMR (CDCl3, 300 K):
d = 13.2 (t, |1J(PC) + 3J(PC)| = 26.8 Hz, PCH3), 76.7 (s,
C„C), 87.0 (s, C„C), 124.2, 125.0, 126.6, 126.7, 127.0,
127.1, 127.2, 127.5, 127.7, 127.8, 128.1, 128.5, 129.8 (s,
CH), 136.0 (s, C@CH), 140.6 (s, Co–C), 185.2 (C–O),
201.1 (C@O) ppm. 31P NMR (CDCl3, 300 K): d =
10.3 ppm (s, PCH3).
2.2.3. Preparation of (1-carbonyl-2-oxo-5-phenyl-
cyclohexene-diyl)-[(Z)-1-phenylethinyl-2-phenylethenyl]-
trans-bis(trimethylphosphine)cobalt(III) (8)
2.2. Procedures
Diphenylbutadiyne (280 mg, 1.39 mmol) was added to a
stirred solution of mer-hydrido-(1-carbonyl-2-oxo-5-phe-
nyl-cyclohexene-diyl)tris(trimethylphosphine) cobalt(III)
(3) (680 mg, 1.39 mmol) in 50 ml of pentane at room tem-
perature. The orange-yellow solution gradually turned
red brown during reaction for 15 h. Red brown precipitate
crystallized from ether to afford brown needle crystal 8.
Yield: 350 mg (41%); m.p. 143–145 ꢁC (dec.). Anal. Calc.
for C35H41CoO2P2 (614.59 g/mol): C, 68.40; H, 6.72.
Found: C, 68.28; H, 6.77%. IR (Nujol): m = 2138 (C„C),
2.2.1. Preparation of (1-carbonyl-2-oxo-cyclohexene-diyl)-
[(Z)-1-phenylethinyl-2-phenylethenyl]-trans-
bis(trimethylphosphine)cobalt(III) (6)
Diphenylbutadiyne (500 mg, 2.48 mmol) was added
to a stirred solution of mer-hydrido-(1-carbonyl-2-oxo-
cyclohexene-diyl)tris(trimethylphosphine)cobalt(III)
(1)
(1000 mg, 2.43 mmol) in 60 ml of pentane at room temper-
ature. The mixture became red brown from orange yellow
within 5 min. After stirring for 15 h, the solution was fil-
tered and the solid residue was extracted with ether to crys-
tallize at 0 ꢁC. Red brown sheet crystals were obtained.
Upon cooling to ꢀ27 ꢁC, a second fraction of crystal 6
was collected. Yield: 600 mg (45%); m.p. 140–142 ꢁC
(dec.). Anal. Calc. for C29H37CoO2P2 (538.49 g/mol): C,
64.68; H, 6.93. Found: C, 64.60; H, 6.95%. IR (Nujol):
m = 2141 (C„C); 1660, 1627 (C@O); 1592, 1544, 1508
1664, 1623 (C@O); 1592, 1542 (C@C) cmꢀ1 1H NMR
.
(d8-THF, 300 K): d = 1.19 (t0, |2J(PH) + 4J(PH)| = 7.8 Hz,
18H, PCH3), 1.83-2.59 (m, 6H, CH2), 2.69 (m, 1H, CH),
6.79 (t, 4J(PH) = 4.2 Hz, 1H, C@CH), 7.01–7.69 (m,
15H, CH) ppm. 13C NMR (d8-THF, 300 K): d = 10.8 (m,
PCH3), 31.2 (s, CH2), 32.8 (s, CH2), 32.9 (s, CH2), 41.9
(s, CH), 78.2 (s, C„C), 104.39 (s, CAC@O), 125.5 (s,
Co–C), 125.0, 125.8, 126.0, 127.0, 127.8, 128.3, 128.4,
128.8, 130.6 (s, CH), 135.0 (s, C@CH), 120.3, 138.6,
147.0 (s, C), 186.4 (s, C–O), 217.8 (s, C@O) ppm. 31P
NMR (d8-THF, 213 K): d = 12.5 (s) ppm.
(C@C) cmꢀ1 1H NMR (d8-THF, 300 K): d = 1.04 (t0,
.
|2J(PH) + 4J(PH)| = 7.6 Hz, 18H, PCH3), 1.36 (m, 2H,
CH2), 1.48 (m, 2H, CH2), 2.08 (s, 4H, CH2), 6.68 (t,
4J(PH) = 3.8 Hz, 1H, C@CH), 6.68–7.56 (m, 10H, CH)
ppm. 13C NMR (d8-THF, 300 K): d = 9.9 (t0,
|1J(PC) + 3J(PC)| = 25.0 Hz, PCH3), 23.2 (s, CH2), 23.31
(s, CH2), 32.4 (s, 2C, CH2), 65.7 (s, C„C), 77.9 (s,
C„C), 124.2, 125.1, 127.0, 127.5, 128.0, 129.8 (s, CH),
119.4, 124.8 (s, C), 134.4 (s, C@CH), 137.9 (s, Co–C),
186.0 (C–O), 217.0 (C@O) ppm. 31P NMR (d8-THF,
300 K) d = 2.8 ppm (s, PCH3).
2.2.4. Preparation of (1-carbonyl-2-oxo-5-tert-butyl-
cyclohexene-diyl)-[(Z)-1-phenylethinyl-2-phenylethenyl]-
trans-bis(trimethylphosphine)cobalt(III) (9)
Diphenylbutadiyne (300 mg, 1.49 mmol) was added to a
stirred solution of mer-hydrido(1-carbonyl-2-oxo-5-tert-
butyl-cyclohexene-diyl)tris(trimethylphosphine) cobalt(III)
(4) (680 mg, 1.46 mmol) in 50 ml of pentane at room tem-
perature. After 15 h, the solid precipitate crystallized from
ether to afford brown crystal 9. Yield: 320 mg (36%); m.p.
139–141 ꢁC (dec.). Anal. Calc. for C33H45CoO2P2
(594.60 g/mol): C, 66.66; H, 7.63. Found: C, 66.50; H,
7.58%. IR (Nujol): m = 2140 (C„C); 1660, 1627 (C@O);
2.2.2. Preparation of (1-carbonyl-2-oxo-1,2-diphenylethene-
diyl)-[(Z)-1-phenylethinyl-2-phenylethenyl]-trans-
bis(trimethylphosphine)cobalt(III) (7)
Diphenylbutadiyne (160 mg, 0.79 mmol) was added
to
a stirred solution of mer-hydrido-(1-carbonyl-2-
oxo-1,2-diphenylethene-diyl)tris(trimethylphosphine) cobalt
(III) (2) (400 mg, 0.78 mmol) in 50 ml of pentane. The yel-
low solution gradually turned red brown within 20 min.
The mixture was kept at room temperature for 18 h during
which a brown precipitate formed. After filtering, the solid
residue was extracted with 80 ml of ether and the solution
was kept at 0 ꢁC to afford red brown crystal 7. Yield:
280 mg (57%); m.p. 133–135 ꢁC (dec.). Anal. Calc. for
C37H39CoO2P2 (536.59 g/mol): C, 69.81; H, 6.17. Found:
C, 69.89; H, 5.96%. IR (Nujol): m = 2133 (C„C); 1630
1592, 1544, 1508 (C@C) cmꢀ1 1H NMR (d8-THF,
.
300 K): d = 1.04 (t0, |2J(PH) + 4J(PH)| = 7.8 Hz, 18H,
PCH3), 0.79 (s, 9H, C(CH3)3), 1.71–2.19 (m, 6H, CH2),
4
2.27 (m, 1H, CH), 6.67 (t, J(PH) = 4.2 Hz 1H, C@CH),
6.67–7.56 (m, 10H, CH) ppm. 13C NMR (d8-THF,
300 K): d = 10.7 (m, PCH3), 27.3 (s, C, C(CH3)3), 32.3 (s,
C(CH3)3), 25.4, 33.5 (s, CH2), 44.1 (s, CH), 77.6 (s,
C„C), 135.1 (s, C@CH), 124.9, 125.8, 127.79, 128.3,
128.7, 130.6 (s, CH) 120.0, 125.5, 138.6 (s, C) ppm. 31P
NMR (d6-Aceton, 300 K): d = 2.8 ppm (m).

X. Li et al. / Inorganica Chimica Acta 359 (2006) 3117–3122
3119
Table 1
Crystal data for compound 6
2.2.5. Preparation of (3-tert-butyl-5-methyl-2-oxobenzoyl)-
[(Z)-1-phenylethinyl-2-phenylethenyl]-trans-
bis(trimethylphosphine)cobalt(III) (10)
Diphenylbutadiyne (210 mg, 1.04 mmol) was added to a
stirred solution of mer-hydrido(3-tert-butyl-5-methyl-
2-oxobenzoyl)tris(trimethylphosphine)cobalt(III) (5) (500
mg, 1.04 mmol) in 50 ml of pentane as described above to
afford red crystal 10. Yield: 180 mg (28%); m.p. 130–
132 ꢁC (dec.). Anal. Calc. for C34H43CoO2P2 (604.59 g/
mol): C, 67.55; H, 7.17. Found: C, 67.48; H, 6.90%. IR
Empirical formula
Formula mass
Crystal size (mm)
Crystal system
Space group
C29H37CoO2P2
538.46
0.49 · 0.46 · 0.11
monoclinic
P2(1)/c
24.239(7)
10.161(3)
11.964(3)
103.084(5)
2870.3(14)
4
˚
a (A)
˚
b (A)
˚
c (A)
b (ꢁ)
3
˚
V (A )
(Nujol): m = 2163 (C„C), 1598, 1565, 1529 (C@C) cmꢀ1
.
Z
1H NMR(CDCl3, 300 K): d = 0.98 (t0, |2J(PH) +
4J(PH)| = 7.0 Hz, 18H, PCH3), 1.53 (s, 9H, C(CH3)3),
2.21 (s, 3H, CH3), 6.90 (s, 1H, C@CH), 6.90–7.90 (m,
Dcalc (g cmꢀ3
)
1.246
0.732
273(2)
l (Mo Ka) (mmꢀ1
)
Temperature (K)
Data collection range (ꢁ)
h
2.18 6 2h 6 25.03
ꢀ28 6 h 6 25
ꢀ12 6 k 6 11
ꢀ14 6 l 6 10
14358
5055 [0.0610]
307
1.021
13
12H, CH) ppm. C NMR (CDCl3, 300 K): d = 11.1 (t0,
|1J(PC) + 3J(PC)| = 26.6 Hz, PCH3), 19.9 (s, CH3), 28.9
(s, C(CH3)3), 34.2 (s, C(CH3)3), 76.7 (s, C„C), 85.1 (s,
C„C), 137.2 (s, C@CH), 117.6, 125.0, 125.2, 127.7,
128.0, 128.1, 130.1 (s, CH), 120.1, 124.2, 130.2, 132.6,
137.2, 137.8 (s, C), 174.6 (s, C–O), 192.0 (s, C@O) ppm.
31P NMR (CDCl3, 300 K): d = 4.4 ppm (s).
k
l
Number of reflections measured
Number of unique data [Rint
Parameters
Goodness-of-fit on F2
R1 [I > 2r(I)]
]
0.0561
wR2 (all data)
0.1692
2.2.6. Preparation of mer-carbonyl-(1-carbonyl-2-oxo-1,2-
diphenyl-diyl)-[(Z)-1-phenylethinyl-2-phenylethenyl]-
trans-bis(trimethylphosphine)cobalt(III) (11)
A 30 ml diethyl ether solution of sample 7 (200 mg,
0.31 mmol) was continuously stirred under 1 bar of CO
at room temperature. The red solution instantly turned yel-
low. After keeping for 2 h, the solution was filtered and
condensed to afford yellow crystal 11 at 0 ꢁC. Yield:
78 mg (37%); m.p. 133–135 ꢁC (dec.). IR (Nujol):
m = 2143 (C„C), 2023 (C„O), 1613 (C@O), 1594, 1535
Table 2
Crystal data for compound 11
Empirical formula
Formula mass
Crystal size (mm)
Crystal system
Space group
C76H78Co2O6P4
1329.12
0.89 · 0.40 · 0.15
triclinic
ꢀ
P1
˚
a (A)
9.5755(17)
12.886(2)
30.823(6)
80.557(2)
89.987(3)
68.158(2)
3474.8(11)
2
(C@C) cmꢀ1
.
1H NMR(CDCl3, 300 K): d = 1.41 (t0,
˚
b (A)
|2J(PH) + 4J(PH)| = 8.2 Hz, 18H, PCH3), 7.02 (s, 1H,
C@CH), 7.03–7.82 (m, 20H, CH) ppm. 13C NMR (CDCl3,
300 K): d = 13.0 (m PCH3), 76.7 (s, C„C), 124.5, 124.8,
125.3, 127.0, 127.5, 128.0, 129.9, 130.1 (s, CH),137.0 (s,
C@CH) 140.6 (m, Co–C), 185.2 (s, C–O), 201.1 (s, C@O)
ppm. 31P NMR (CDCl3, 300 K): d = 9.9 ppm (s).
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
3
˚
V (A )
Z
Dcalc (g cmꢀ3
)
1.270
0.620
l (Mo Ka) (mmꢀ1
)
Temperature (K)
Data collection range (ꢁ)
h
293(2)
2.2.7. Crystal structure analyses
1.73 6 2h 6 25.00
ꢀ8 6 h 6 11
ꢀ14 6 k 6 15
ꢀ36 6 l 6 33
17759
11987 [0.0331]
806
1.047
Crystal data for compounds 6 and 11 are presented
in Tables 1 and 2. The single crystals were mounted on a
Bruker AXS P4 diffractometer. Reflections were mea-
sured using graphite-monochromated Mo Ka radiation
k
l
Number of reflections measured
Number of unique data [Rint
Parameters
Goodness-of-fit on F2
R1 [I > 2r(I)]
]
˚
(k = 0.71073 A). The structures were solved by direct meth-
ods. Full-matrix least-squares refinement based on F2 was
used. All non-hydrogen atoms were anisotropically refined.
Program such as SHELXTL was used.
0.0695
0.1714
wR2 (all data)
3. Results and discussion
unsaturated acyl vinyl cobalt(III) complexes 6–10 contain-
ing 1,4-diphenylbut-1-en-3-yn-2-yl ligand, g1-C(C„
CPh)@CHPh, by mono-insertion of the diyne into the
Co–H bond accompanying one trimethylphosphine ligand
leaving. The reactions proceeded at room temperature in
pentane extending over 15–18 h.
3.1. Mono-insertion reaction with diphenylbutadiyne
Reactions of 2-acyl enolato hydrido cobalt(III) com-
plexes 1–4 and 2-acyl phenolato hydrido cobalt(III) com-
plex 5 with diphenylbutadiyne form five-coordinatively

3120
X. Li et al. / Inorganica Chimica Acta 359 (2006) 3117–3122
R
O
O
O
pentane, single crystals of 6 for X-ray diffraction analysis
were obtained.
PMe
Co
3H
PMe3
O
Ph
Co
(PhC
C)2
+
The molecular structure of compound 6 is shown in
Fig. 1. The structure is similar to that of (3-tert-butyl-5-
methyl-2-oxobenzoyl)(1-ethoxocarbonyl-1-vinyl)-trans-bis
(trimethylphosphine)cobalt(III) [8]. The cobalt atom cen-
ters in the square plane of the square pyramidal and attains
a coordination with two equatorial phosphor atoms of
trans-trimethylphosphine ligands and a carbon atom of
vinyl group and an oxygen atom of phenoxy group. The
carbon atom of acyl group is situated at the apex point
of the square pyramidal geometry.
R
PMe3
Me3P
PMe3
Ph
1-5
6-10
Ph
Ph
Ph
=
R
,
,
,
,
Angular distortion of C1–Co–C8 = 105.2ꢁ may result
from the bulky r-phenylvinyl ligand. The chelating acyl-
phenolato ligand with a chelate-bite angle C1–Co1–
O1 = 86.2ꢁ spans apical and basal positions in the square
pyramid. The phenyl ring (C10–C15) in phenyl vinyl group
is rotated out of the square plane (P1C8P2O1) with a dihe-
dral angle of 116.3ꢁ and the phenyl group (C18–C23) in
phenyl alkynyl moiety is rotated out of the square plane
(P1C8P2O1) with a dihedral angle of 93.3ꢁ. A folding angle
of 98.1ꢁ is observed between these two phenyl rings. C1–O2
1, 6
2, 7
3, 8
4, 9
5, 10
ð1Þ
Crystals or powders 6–10 were obtained from diethyl
ether or pentane solution. In infrared spectra, typical sig-
nals for the vibration of (Co–H) bond are absent and the
valence vibration of C„C bonds (2133–2141 cmꢀ1) are
observed, indicating that mono-insertion reactions took
place.
1
From H NMR spectroscopy, we know that a pseudo-
˚
bond length (1.219(6) A) is slightly shorter than previously
triplet between 0.98 and 1.14 ppm with strong coupling
|2J(PH) + 4J(PH)| = 7.0–7.8 Hz is recorded for two trans-
PMe3 ligands. Signals of vinylic proton of the alkenyl
group are found in the region of 6.67–6.79 ppm. In 31P
NMR spectrum, a singlet is detected indicating two trim-
ethylphosphine ligands in the same chemistry surround-
ings. The magnetic properties of these compounds
confirm that these complexes have a square pyramidal
configuration with two trans-trimethylphosphine ligands
in the square plane. This conjecture is verified through
X-ray single crystal diffraction. By crystallization from
reported acyl cobalt complexes. Co–C8 bond length
˚
(1.917(5) A) falls in the typical range for r-vinyl com-
˚
plexes. Co–C1 with 1.909 A is shorter than that of the
six-coordinate hydrido acyl phenolato cobalt(III) com-
˚
plexes with Co–C1 from 1.925 to 1.952 A [9]. Displacement
of the Co atom is toward the acyl group. These effects can
be explained by a stronger Co–C bonding interaction with-
out the sixth ligand in the trans-position of acyl group,
which would normally compete with alkyl for the metal
dz2 orbital. The metallation steers at position 2 of the
˚
Fig. 1. Molecular structure of 6: selected bond distances (A) and bond angles (ꢁ): Co1–C1 1.909(6), Co1–C8 1.917(5), Co1–O1 1.953(4), Co1–P1 2.220(1),
Co1–P2 2.231(2), C1–O2 1.219(6), C8–C9 1.350(7), C16–C17 1.206(7); C1–Co–O1 86.2(2), C1–Co1–P1 89.6(2), C1–Co1–P2 92.5(2), C1– Co1–C8 105.2(2),
P1–Co1–P2 177.93(6), O1–Co1–C8 168.5(2), C8–C16–C17 174.1(6), C16–C17–C18 174.1(5).

X. Li et al. / Inorganica Chimica Acta 359 (2006) 3117–3122
3121
˚
Fig. 2. Molecular structure of 11: selected bond distances (A) and bond angles (ꢁ): Co2–C76 1.886(5), Co2–C8 2.008(4), Co2–C23 1.974(4), Co2–O1
1.967(3), Co2–P3 2.222(1), Co2–P4 2.213(1), C1–O2 1.219(6), C6–C7 1.477(6), C7–C8 1.352(6), C8–C9 1.415(6), C9–C10 1.207(6), C10–C11 1.427(6),
C23–Co2–C76 165.1(2), C8–Co2–O1 176.0(2), P4–Co2–P3 167.50(6), C76–Co2–O1 81.60(2), C76–Co2–C8 94.4(2), Co2–C76–O3 170.1(5), C8–Co2–C23
100.5(2), C23–Co2–O1 83.6(2) C8–C9–C10 175.4(5), C9–C10–C11 173.1(5).
C-chain of the butadiyne. It is supposed that the regioselec-
tivity of the insertion reaction with diphenylbutadiyne is
similar to that with bis(trimethylsilyl)butadiyne in view of
steric factor.
instantly accompanying obvious change of the color of
the solution from red-brown to yellow.
Ph
Ph
O
O
O
PMe3
It is interesting to note that a reversible 16–18 electron
interconversion is present as shown in Eq. (2). Treatment
of 6–10 with an excess of PMe3 at room temperature pro-
ceeded smoothly monitored by the change in the red color
of the solution to yellow. But at room temperature only
the five coordinated acyl vinyl cobalt(III) complexes were
isolated. In the case of insertion reaction with bis(trimeth-
ylsilyl)butadiyne [7], the reversible 16–18 electron inter-
conversion is also present at lower temperature, and
hexa-coordinated acyl vinyl cobalt(III) complexes were
successfully isolated at room temperature.
Ph
PMe3
Ph
Ph
pentane
O
Ph
CO
Co
+
Co
CO
Ph
Me3P
PMe3
Ph
7
11
ð3Þ
A strong infrared absorption 2023 cmꢀ1 shows the exis-
tence of a terminal carbonyl ligand. 1H NMR spectroscopy
indicates a pseudo-triplet by 1.41 ppm with strong coupling
|2J(PH) + 4J(PH)| = 8.2 Hz, which is recorded for the two
trans-PMe3 ligands.
R
O
R
O
PMe3
PMe3
PMe3
PMe3
O
Ph
O
Ph
Co
Co
By re-crystallization from pentane at 4 ꢁC, single crys-
tals of 11 as yellow plate for an X-ray diffraction analysis
were obtained. A view of the molecular geometry is shown
in Fig. 2 with selected bond distances and bond angles. The
molecular structure of 11 (Fig. 2) shows an expected octa-
hedral configuration of monocarbonyl acyl cobalt(III)
complex with the CO group in a position opposite to the
acyl function and two trans trimethylphosphine ligands in
axial position. This structure is related to that of mer-car-
bonyl-(1-carbonyl-2-oxo-cyclohexen-diyl)-[(Z)-1-trimethyl-
silylethinyl-2-trimethylsilylethenyl]-trans-bis(trimethylpho-
sphine) cobalt(III) [7]. As a result of trans-influence of acyl
ð2Þ
Me3P
Me3P
PMe3
Ph
Ph
6 - 10
3.2. Reaction with carbon monoxide
Complexes 1–5 are formal 16-electron species. They are
stable in solid state. But in solution they are highly reactive
toward CO. Carbon monoxide easily coordinates to
16-electron acyl cobalt(III) complexes, leading to the for-
mation of coordinatively saturated configurations. The
reaction of acyl cobalt(III) complex 7 with carbon monox-
ide proceeds smoothly in diethyl ether solution under 1 bar
of CO at room temperature. The reaction takes place
˚
unit, distance Co2–C76 with 1.886(5) A in trans-position to
acyl group is considerably longer than the corresponding
˚
bond (1.782(9) A) in cobalt(III) complex, [CpCo(dppe)-
CO](PF6)2 Æ (CH3)2CO [11]. Under the experimental

3122
X. Li et al. / Inorganica Chimica Acta 359 (2006) 3117–3122
conditions, insertion of CO into the Co–C bond was not
observed.
ited as supplementary material with the Cambridge Crys-
tallographic Data Centre. Deposition number is CCDC-
273386 for 6 and CCDC-273395 for 11. Copies of the data
can be obtained free of charge on application to CCDC, 12
Union Road, Cambridge, CB2 1EZ, UK (fax: +44 1223
336 033; e-mail: deposit@ccdc.cam.ac.uk). Supplementary
data associated with this article can be found, in the online
version, at doi:10.1016/j.ica.2006.03.029.
4. Conclusion
We have reported the formation of five new five-
coordinate acyl vinyl cobalt(III) complexes Co{g1-
C(C„CPh)@CHPh}[C(O)AC@CAO ]L2 (L = PMe3) (6–
10) through the formal insertion of diphenylbutadiyne into
Co–H function of mer-octahedral hydrido acyl(phenolato)-
cobalt(III) complexes. These complexes are characterized
with NMR and IR spectroscopy. The complexes are dia-
magnetic. One square pyramidal structure of complex 6
was confirmed by X-ray crystallography. The complexes
are stable in solid state. In solution, hexa-coordinate acyl
vinyl carbonyl cobalt(III) complex 11 was approved
through the reaction of complex 7 with CO and the struc-
ture of complex 11 was determined by X-ray method.
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We gratefully acknowledge support by the Excellent
Young Teachers Program of MOE, the Scientific Research
Foundation for the Returned Overseas Chinese Scholars,
SEM and NSFC Nos. 20572062 and 20372042, as well as
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Appendix A. Supplementary data
Crystallographic data (excluding structure factors) for
the structure described in this publication have been depos-