Reaction of acyl(hydrido)cobalt(III) complexes with (2-diphenylphosphanyl)thiophenol and the influence of chelating ligands containing hard/soft donor atoms on the stability of cobalt complexes

Article abstract of DOI:10.1016/j.poly.2007.11.010

The reaction of acyl(hydrido)cobalt(III) complexes Co^III(O^∩C{double bond, long}O)(H)(PMe₃)₃ (1-5) with (2-diphenylphosphanyl)thiophenol afforded four types of complexes Co^III(O^∩C{double bond, long}O)(P^∩S)(PMe₃)₂ (6-7), Co^III(O^∩C{double bond, long}O)(O^∩OHC)(PMe₃)₂ (11-15), Co^I(P^∩S)(PMe₃)₃ (16), and Co^II(P^∩S)₂(PMe₃) (17). A mechanism for the formation of these complexes is proposed. The influences of chelating ligands containing hard/soft donor atoms on the stability of the cobalt complexes in different oxidation states are discussed with respect to the HSAB concept.

Full text of DOI:10.1016/j.poly.2007.11.010

Available online at www.sciencedirect.com
Polyhedron 27 (2008) 854–860
www.elsevier.com/locate/poly
Reaction of acyl(hydrido)cobalt(III) complexes
with (2-diphenylphosphanyl)thiophenol and the influence
of chelating ligands containing hard/soft donor atoms
on the stability of cobalt complexes
Hongjian Sun a, Lei She a, Shimin Fang a,b, Xiaoyan Li a,*
a School of Chemistry and Chemical Engineering, Shandong University, Shanda Nanlu 27, 250100 Jinan, People’s Republic of China
b Shandong Institute of Light Industry, Daxue Road Western University Science Park, 250353 Jinan, People’s Republic of China
Received 4 September 2007; accepted 13 November 2007
Available online 20 December 2007
Abstract
The reaction of acyl(hydrido)cobalt(III) complexes CoIII(O\C@O)(H)(PMe3)3 (1–5) with (2-diphenylphosphanyl)thiophenol afforded
four types of complexes CoIII(O\C@O)(P\S)(PMe3)2 (6–7), CoIII(O\C@O)(O\OHC)(PMe3)2 (11–15), CoI(P\S)(PMe3)3 (16), and
CoII(P\S)2(PMe3) (17). A mechanism for the formation of these complexes is proposed. The influences of chelating ligands containing
hard/soft donor atoms on the stability of the cobalt complexes in different oxidation states are discussed with respect to the HSAB
concept.
Ó 2007 Elsevier Ltd. All rights reserved.
Keywords: Hydridocobalt(III) complex; [P,S]-chelating ligand; Hard/soft donor; Structure
1. Introduction
chelating (2-diphenylphosphanyl)thiophenolato ligand
was introduced.
Acyl(hydrido)cobalt species stabilized by a (2-acyl)-phe-
nolato chelating ligand and supported by trimethylphos-
phine ligands were intensively studied by Klein and
co-workers [1–5]. The reactions of (acylphenolato)hydri-
docobalt(III) complexes with 2-nitrophenol and (2-diphen-
ylphosphanyl)phenol were reported [3,4]. The stability of
these diorgano bis-chelating complexes was discussed
according to HSAB theory. In order to better understand
the relationship between the properties of different ligands,
molecular structures of cobalt complexes, and stabilities of
compounds in different oxidation states, instead of 2-nitro-
phenol and (2-diphenylphosphanyl)phenol, the soft/soft
2. Experimental
2.1. Materials and methods
Standard vacuum techniques were used in manipula-
tions of volatile and air-sensitive materials. Acyl(hydrido)
cobalt(III) complexes (1–5) [1], (2-diphenylphospha-
nyl)thiophenol were synthesized according to literature
procedures [6]. C, H analyses were carried out in an
Elementor Vario III analyzer. Infrared spectra (4000–
400 cmꢀ1), as obtained from Nujol mulls between KBr
discs, were recorded on NICOLET 5700. H,13C and 31P
1
*
NMR spectra were obtained from Bruker AVANCE 300
spectrometer (300, 75 and 121 MHz, respectively) or
Corresponding author.
E-mail address: xli63@sdu.edu.cn (X. Li).
0277-5387/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2007.11.010

H. Sun et al. / Polyhedron 27 (2008) 854–860
855
Bruker AVANCE 400 spectrometer (400, 100 and
2.2.2. [(3,5-Di-tert-butyl-2-oxobenzoyl)
162 MHz, respectively). 13C and 31P NMR resonances were
obtained with broad-band proton decoupling. Melting
points were measured in capillaries sealed under argon
and are uncorrected.
(2-diphenylphosphanyl)thiophenyl(S,P)]bis(trimethyl-
phosphine)cobalt(III) (7) and [(3,5-di-tert-butyl-
2-oxobenzoyl)(2,4-di-tert-butyl-6-formyl)-
phenolato(O,O)]bis(trimethylphosphine)cobalt(III) (12)
A sample of mer-hydrido(3,5-di-tert-butyl-2-oxobenzoyl)
tris(trimethylphosphine)cobalt(III) (2) (1.45 g, 2.78 mmol)
in 80 ml of diethyl ether and (2-diphenylphosphanyl)thio-
phenol (0.82 g, 2.79 mmol) in 10 ml of THF after stirring
for 18 h at room temperature gave a red-brown suspension.
After evaporating the volatiles in vacuo a red-brown resi-
due was obtained. Pentane, diethyl ether, and THF were
used in turn to extract the residue, and the three filtrates
were crystallized at ꢀ27 °C. 7 was collected from pentane
as a red needles: 0.10 g, yield 5% (based on 2) from which
some crystals of 17 could be mechanically separated. 16
was obtained from diethyl ether: 0.62 g (yield 38%). From
THF 12 was obtained as dark-red cubic crystals: 0.26 g
(yield 28% based on 2). 7: m.p. (dec.) > 132 °C. Anal. Calc.
for C39H52CoO2P3S (736.75 g/mol): C, 63.58; H, 7.11.
Found: C, 63.61; H, 7.08%. IR (Nujol mull, 2600–l500
cmꢀ1): 1620 m, 1593 s m(C@O); 1526 m, m(C@C). 1H
NMR (300 MHz, CDCl3, 295 K, ppm): d(CCH3) 1.12 (s,
9H); d(PCH3) 1.24 (t0,|2J(PH) + 4J(PH)| = 8.1 Hz, 18H);
d(CCH3) 1.67 (s, 9H); d(CHarom) 6.69–8.49 (m, 16H). 31P
NMR (121 MHz, CD3Cl, 295 K, ppm): d(PCH3) 12.1 (s,
2P); d(PPh2) 20.1 (s, 1P). 12: m.p. (dec.) > 187 °C. Anal.
Calc. for C36H59CoO4P2 (676.73 g/mol): C, 63.89; H,
8.79. Found: C, 63.79; H, 8.83%. IR (Nujol mull, 2600–
2.2. Synthesis of the complexes
2.2.1. trans-[(1-Carbonyl-2-oxo-cyclohexenediyl)-
(2-diphenylphosphanyl)thiophenyl(S,P)]bis-
(trimethylphosphine)cobalt(III) (6)
To
a
suspension of mer-hydrido(1-carbonyl-2-
oxo-cyclohexenediyl)tris(trimethylphosphine)cobalt(III) (1)
(1.27 g, 3.07 mmol) in 60 ml of diethyl ether (2-diphenyl-
phosphanyl)thiophenol (0.92 g, 3.12 mmol) dissolved in
20 ml of diethyl ether was added slowly at ꢀ80 °C. When
the mixture was stirred at ambient temperature for 18 h,
the solution changed from yellow to dark-red. After evap-
orating the volatiles under vacuum, the residue was
extracted with pentane and diethyl ether. Both filtrates
were crystallized at ꢀ27 °C. From pentane solution com-
plex 6 was obtained as dark-red cubic crystals which
turned to effloresce under vacuum. Yield: 0.17 g of 6 (9%
based on 1). 17 was also obtained from pentane as
brown-yellow cubic crystals suitable for X-ray diffraction
analysis. Yield: 0.09 g of 17 (8% based on (2-diphenylphos-
phanyl)thiophenol). From THF 11 could be obtained as
red microcrystals: 0.18 g (yield 25%, based on 1). From
diethyl ether 16 was isolated as brown crystals: 0.61 g
(yield 33% based on (2-diphenylphosphanyl)thiophenol).
6: m.p. (dec.) > 142 °C. Anal. Calc. for C31H40CoO2P3S
(628.57 g/mol): C, 59.23; H, 6.41. Found: C, 59.31; H,
6.38%. IR (Nujol mull, 2600–l550 cmꢀ1): 1608 s, m(C@O);
1557 s, m(C@C). 1H NMR (300 MHz, C6D6, 296 K,
ppm): d(PCH3) 0.825 (t0,|2J(PH) + 4J(PH)| = 8.1 Hz,
18H); d(C–CH2–CH2) 1.63 (m, 4H); d(CCH2) 2.37 (s,
2H); d(CCH2) 2.78 (s, 2H); d(CHarom) 6.93–8.36 (m,
14H). 13C NMR (75 MHz, C6D6, 298 K, ppm): d(PCH3)
13.22 (t0,|1J(PC) + 3J(PC)| = 27 Hz); d(CH2) 23.9, 24.2,
24.4, 33.3; d(Carom) 113.4, 120.2, 125.6, 129.3, 131.6,
132.2, 133.6, 138.6, 140.5; d(CO), 165.9; d(CCO), 189.5.
31P NMR (121 MHz, C6D6, 296 K, ppm): d(PCH3)
ꢀ1.44 (s, 2P); d(PPh2), 32.9 (s, 1P). 11: m.p. (dec.) >
145 °C. Anal. Calc. for C20H35CoO4P2 (460.37 g/mol): C,
52.18; H, 7.66. Found: C, 52.01; H, 7.72%. IR (Nujol mull,
2600–l500 cmꢀ1): 1592 s, m(C@O); 1550, 1530 s, m(C@C).
1H NMR (300 MHz, CDCl3, 293 K, ppm): cis/trans-
1
l500 cmꢀ1): 1656 s, 1608 s m(C@O); 1513 m, m(C@C). H
NMR (300 MHz, C6D6, 296 K, ppm): d(PCH3) 0.79
(d,2J(PH) = 8.1 Hz, 18H); d(CCH3) 1.21 (s, 9H);
d(CCH3) 1.32 (s, 9H); d(CCH3) 1.55 (s, 9H); d(CCH3)
1.61 (s, 9H); d(CHarom) 6.96–7.99 (m, 4H); d(CHO) 9.55
(s, 1H). 31P NMR (121 MHz, C6D6, 296 K, ppm):
d(PCH3) 14.2 (s).
2.2.3. (2-Oxo-naphthalene-formyl)[(1-formyl)naphtholato-
(O,O)]bis(trimethylphosphine)cobalt(III) (13)
A sample of mer-hydrido(2-oxo-naphthalene-formyl)
tris(trimethylphosphine)cobalt(III) (3) (1.49 g, 3.25 mmol)
in 60 ml of diethyl ether and (2-diphenylphosphanyl)thio-
phenol (0.95 g, 3.25 mmol) in 20 ml of diethyl ether after
stirring for 18 h at room temperature gave a red-brown
suspension. After evaporating the volatiles in vacuo a
red-brown residue was obtained. Pentane, diethyl ether
and THF were used in turn to extract the residue, and
the three filtrates were crystallized at ꢀ27 °C. 0.66 g 16
were obtained from diethyl ether (yield 35%). From THF
13 could be obtained as red microcrystals: 0.30 g (yield
33%, based on 3). 13: m.p. (dec.) > 257 °C. Anal. Calc.
for C28H31CoO4P2 (552.42 g/mol): C, 60.88; H, 5.66.
Found: C, 60.92; H, 5.50%. IR (Nujol mull, 2600–l500
cmꢀ1): 1613 s, 1584 s m(C@O); 1552 m, 1536 m, m(C@C).
1H NMR (300 MHz, CDCl3, 295 K, ppm): d(PCH3) 1.25
(t0,| 2J(PH) + 4J(PH)| = 9.4 Hz, 18H); d(CH) 6.68–9.51
2
11 = 2/1. cis-11: d(PCH3) 1.18 (d, J(PH) = 9.1 Hz, 18H);
4
d(CHO) 7.55 (d, J(PH) = 9.6 Hz, 1H). trans-11: d(PCH3)
1.15 (s, 18H); d(CHO) 8.40 (s, 1H); without assignmet:
d(CH2) 1.40–2.53 (m, 16H).31P NMR (121 MHz, CDCl3,
294 K, ppm): cis-11: d(PCH3) 19.0 (s, br); trans-11:
d(PCH3) 12.4 (s, br).
17: m.p. (dec.) > 230 °C. Anal. Calc. for C39H37CoP3S2
(721.7 g/mol): C, 64.91; H, 5.17. Found: C, 64.83; H,
5.24%. IR (Nujol mull, 2600–l500 cmꢀ1): 1575 s, m(C@C).

856
H. Sun et al. / Polyhedron 27 (2008) 854–860
(m, 12H); d(CHO) 10.37 (s, 1 H). 31P NMR (121 MHz,
CDCl3, 295 K, ppm): d(PCH3) 18.1 (s).
2.2.4. (1-Carbonyl-2-oxo-1,2-diphenylethenyl)[(1-formyl-2-
oxo-1,2-diphenylethenyl)(O,O)]bis(trimethylphosphine)-
cobalt(III) (14)
A sample of mer-hydrido(1-carbonyl-2-oxo-1,2-diph-
enylethenediyl)tris(trimethylphosphine)cobalt(III)
(4)
(0.64 g, 1.25 mmol) in 40 ml of diethyl ether and (2-diphen-
ylphosphanyl)thiophenol (0.37 g, 1.23 mmol) in 10 ml of
diethyl ether after stirring for 18 h at 20 °C gave a red-
brown suspension. After evaporating the volatiles in vacuo
a red-brown residue was obtained. Pentane, diethyl ether
and THF were used in turn to extract the residue, and
the three filtrates were crystallized at ꢀ27 °C. From diethyl
ether 0.22 g of 16 were obtained (30% yield). From THF 14
was obtained as yellow powder: 0.10 g (yield 25% based on
4). 14: m.p. (dec.) > 168 °C. Anal. Calc. for C36H39CoO4P2
(656.57 g/mol): C, 65.85; H, 5.99. Found: C, 65.53; H,
5.54%. IR (Nujol mull, 2600–l500 cmꢀ1): 1692 s, 1608 s
˚
Fig. 2. Molecular structure of 17. Selected distances (A) and angles (°):
Co1–P2 2.1949(18), Co1–P1 2.2055(18), Co1–S1 2.220(2), Co1–S2 2.70(2),
Co1–P3 2.279(2); P2–Co1–P1 152.53(8), P2–Co1–S1 90.49(8), P1–Co1–S1
87.69(7), P2–Co1–S2 84.24(7), P1–Co1–S2 91.34(7), S1–Co1–S2 166.63(8),
P2–Co1–P3 103.41(7), P1–Co1–P3 103.94(7), S1–Co1–P3 99.29(9), S2–
Co1–P3 93.89(8).
1
m(C@O); 1531 m, 1536 s, m(C@C). H NMR (300 MHz,
2.2.5. (3-Methoxy-2-oxobenzoyl)[(2-methoxy-6-
formyl)phenolato(O,O)]bis(trimethylphosphine)
cobalt(III) (15)
A sample of mer-hydrido(3-methoxy-2-oxobenzoyl)-
tris(trimethylphosphine)cobalt(III) (5) (1.40 g, 3.20 mmol)
in 60 ml of diethyl ether and (2-diphenylphosphanyl)
acetone-d6,
296 K,
ppm):
d(PCH3)
1.37
(dd,
2J(PH) = 9.9 Hz, 4J(PH) = 1.8 Hz, 18 H); d (CH) 6.89–
7.94 (m, 15H); d(CHO) 9.19 (s, 1H). 31P NMR (121
MHz, acetone-d6, 296 K, ppm): d(PCH3) 22.8 (s).
Table 1
Crystallographic data of complexes 15 and 17
15
17
Formula
Mr (g/mol)
Color
C
22H31CoO6P2
C43H47CoOP3S2
795.77
512.34
orange
triclinic
brown-yellow
monoclinic
P2(1)/n
15.051(3)
12.076(2)
21.916(4)
90
102.16(3)
90
3894.0(13)
4
Crystal system
Space group
ꢀ
P1
˚
a (A)
10.068(4)
10.785(4)
11.580(5)
90.701(7)
107.007(7)
96.529(7)
1193.3(8)
2
˚
b (A)
˚
c (A)
a (°)
b (°)
c (°)
3
˚
V (A )
Z
qcalc. (g/cm3)
1.426
0.888
1.357
0.705
l (mmꢀ1
)
Scan range (°)
1.84 6 h 6 25.50
ꢀ10 6 h 6 12,
ꢀ13 6 k 6 13,
ꢀ11 6 l 6 14
6380
1.84 6 h 6 25.05
ꢀ15 6 h 6 17,
ꢀ12 6 k 6 14,
ꢀ25 6 l 6 25
12676
Reflections collected
Rint
0.0504
0.0857
Independent
reflections
Data/restraints/
parameters
Goodness-of-fit on F2 0.951
Final R indices
[I > 2r(I)]
4343
6678
˚
Fig. 1. Molecular structure of cis-15. Selected distances (A) and angles (°):
4343/0/288
6678/0/54
Co1–C1 1.914(6), Co1–O1 1.918(3), Co1–O4 1.926(3), Co1–O2 2.071(4),
Co1–P2 2.1810(18), Co1–P1 2.2239(18), O2–C9 1.239(6), O5–C1 1.212(6);
C1–Co1–O1 87.12(18), C1–Co1–O4 87.1(2), O1–Co1–O4 88.52(15),
C1–Co1–O2 169.8(2), O1–Co1–O2 91.77(15), O4–Co1–O2 82.66(14),
C1–Co1–P2 88.49(16), O1–Co1–P2 175.54(12), O4–Co1–P2 90.45(11),
O2–Co1–P2 92.40(11), C1–Co1–P1 97.69(18), O1–Co1–P1 83.06(12),
O4–Co1–P1 170.04(12), O2–Co1–P1 92.26(11), P2–Co1–P1 98.35(7).
0.811
R1 = 0.0739,
R1 = 0.0584,
wR2 = 0.1212
R1 = 0.1475,
wR2 = 0.1473
wR2 = 0.1464
R1 = 0.1129,
wR2 = 0.1643
R indices (all data)

H. Sun et al. / Polyhedron 27 (2008) 854–860
857
thiophenol (0.94 g, 3.20 mmol) in 20 ml of diethyl ether after
stirring for 18 h at 20 °C gave a red-brown suspension. After
evaporating the volatiles in vacuo a red-brown residue was
obtained. Pentane, diethyl ether and THF were used in turn
to extract the residue, and the three filtrates were crystallized
at ꢀ27 °C. From diethyl ether 16 was obtained (0.72 g, yield
40%). From THF 15 was obtained as orange crystals of
(0.35 g yield 43% based on 5). 15: m.p. (dec.) > 202 °C. Anal.
Calc. for C22H31CoO6P2 (512.36 g/mol): C, 51.57; H, 6.10.
Found: C, 51.69; H, 6.28%. IR (Nujol mull, 2600–
l500 cmꢀ1): 1646 s, 1616 s, m(C@O); 1579 s, 1537 s,
6 °C. The molecular structures are shown in Fig. 1 and
Fig. 2, respectively, and related crystallographic data are
included in Table 1. The structures were solved by direct
methods and refined with full-matrix least-squares on all
F2 (SHELXL-97) with non-hydrogen atoms anisotropically.
3. Results and discussion
The acyl(hydrido)cobalt complexes 1 and 2 were reacted
with (2-diphenylphosphanyl)thiophenol in diethyl ether.
After careful work-up, apart from the expected novel
cobalt complexes 6 and 7 containing one 2-acylphenolato
ligand and one (2-diphenylphosphanyl)thiophenolato
ligand, three additional types of cobalt complexes, 11, 12,
16, and 17 were successfully isolated and shown to exist
in different formal oxidation states (Eqs. (1) and (2)).
Complexes 6 and 7 are stable below 142 °C and 132 °C
under inert atmosphere. In the IR spectra the conspicuous
m(Co–H) absorption of the acyl(hydrido)cobalt complexes
(complex 1 and 2) are absent.
1
m(C@C). H NMR (400 MHz, CDCl3, 293 K, ppm): cis/
trans-15 = 1/3. cis-15: d(PCH3) 1.01 (t0,|2J(PH) + 4J(PH)|
= 13.4 Hz, 9H); d(PCH3) 1.22 (t0,| 2J(PH) + 4J(PH)|
= 10.9 Hz, 9H); d(OCH3) 3.72 (s, 3H); d(OCH3) 3.77 (s,
3H); d(CHO) 9.7 (s, 1H). trans-15: d(PCH3) 1.24
(t0,|2J(PH) + 4J(PH)| = 13.7 Hz, 18H); d(OCH3) 3.32 (s,
3H); d(OCH3) 3.57 (s, 3H); d(CHO) 9.46 (s, 1H), without
assignmet: d(CH) 6.89–7.94 (m, 15H). 31P NMR
(121 MHz, CDCl3, 296 K, ppm): cis-15: d(PCH3) 4.1(s,
1P), 8.1(s, 1P); trans-15: d(PCH3) 2.3 (s, 1P).
1
The H and 31P NMR spectra of complexes 6 and 7 are
well resolved. The pattern of PCH3 signals as pseudotri-
plets are is consistent with an octahedral coordination
geometry and two trans-trimethylphosphine ligands. Two
31P NMR singlets represent one diphenylphosphanyl group
and two isochronic trimethylphosphine ligands. Due to
2.3. X-ray diffraction
Crystals of complexes 15 and 17 suitable for X-ray dif-
fraction analysis were grown from THF and pentane at
H
H
PMe3
PMe3
O
O
PMe3
Me3P
O
O
SH
O
H
Co
O
Co
+
Co
+
PMe3
O
O
PPh2
O
O
PMe3
PMe3
1
cis-11
trans-11
ð1Þ
Ph
O
O
Ph
PMe3
Co
Ph
Ph
Ph
Ph
PMe3
Co
P
PMe3
P
S
P
Co
+
+
+
PMe3
S
S
P
S
PMe3
PMe3
Ph
Ph
O
6
16
17
H
H
PMe3
O
PMe3
O
O
O
PMe3
Me3P
O
SH
H
Co
Co
Co
+
+
PMe3
O
O
PPh2
O
O
PMe3
PMe3
2
ð2Þ
cis-12
trans-12
Ph
P
O
O
PMe3
Ph
16
17
+
+
+
Co
S
PMe3
7

858
H. Sun et al. / Polyhedron 27 (2008) 854–860
H
H
PMe3
O
PMe3
O
O
O
O
PMe3
Co
Me3P
O
SH
H
O
Co
Co
+
+
O
PMe3
O
O
PPh2
PMe3
PMe3
cis-13
trans-13
3
ð3Þ
Ph
O
O
PMe3
Co
Ph
P
+
17
16
+
+
S
PMe3
8
H
Ph
P
H
PMe3
O
O
O
O
O
PMe3
Co
PMe3
O
Ph
O
O
PMe3
Co
Me3P
Ph
Ph
Ph
Ph
SH
16
17
+
Ph
Ph
+
+
H
O
Co
Co
+
ð4Þ
+
O
Ph
S
Ph
O
Ph
Ph
PMe3
O
Ph
PPh2
PMe3
PMe3
PMe3
Ph
9
4
cis-14
trans-14
H
H
PMe3
O
PMe3
O
O
O
PMe3
Me3P
O
SH
H
Co
Co
Co
+
+
O
PMe3
O
O
O
PPh2
O
PMe3
PMe3
OMe
OMe
OMe
OMe
5
OMe
cis-15
trans-15
ð5Þ
Ph
O
PMe3
Ph
P
Co
16
17
+
+
+
S
O
PMe3
OMe
10
O
efflorescence of crystals the crystal structure of complex 6
could not be determined by X-ray diffraction.
In the case of complexes 3–5, the analogous reactions
according to Eqs. (3)–(5) have been carried out without
successfully isolating the expected complexes 8, 9, and 10
due to very low yields of these compounds.
O
O
PMe3
H
H
OH
Co
+
R
R
PMe3
PMe3
1-5
As by-products, the bis-chelate complexes 11–15 were
obtained from the reactions (Eqs. (1)–(5)) as yellow to
orange crystals. In the 1H NMR spectra the aldehyde
protons appear between 9 and 10 ppm. X-ray diffraction
indicates that complex 15 attains an octahedral configura-
tion with two trimethylphosphine groups in cis-positions,
while the two 2-acylphenolato ligands are arranged perpen-
dicular to each other (Fig. 1). Complexes 11–15 could be
isolated as cis and trans isomers. The ratio of the isomers
H
H
PMe3
O
PMe3
O
O
Me3P
O
PMe
H2,
3
Co
+
Co
R
R
R
O
O
O
O
PMe3
R
cis-(11-15)
trans-(11-15)
ð6Þ
1
was determined from H NMR and 13P NMR data. Crys-
From each reaction in Eqs. (1)–(5) cobalt(I) complex 16
with one [P,S]-chelating ligand was obtained in good yield
(>30%). The direct synthesis of complex 16 can be achieved
by reaction of (2-diphenylphosphanyl)thiophenol with
methyl tetrakis(trimethylphosphine)cobalt(I), CoMe(PMe3)4,
or by reaction of (2-diphenylphosphanyl)thiophenol with
talline materials of all these complexes are stable in the air
at room temperature.
Complexes 11–15 can be directly prepared by the reac-
tion of acyl(hydrido)cobalt 1–5 with the corresponding b-
hydroxy aldehyde (Eq. (6)) [5].

H. Sun et al. / Polyhedron 27 (2008) 854–860
859
tris(trimethylphosphine)cobalt(I), CoX(PMe3)3, (Eqs. (7)
and (8)) [7].
cubic crystals. The molecular structure (Fig. 2) shows the
expected square-pyramidal geometry of complex 17. The
cobalt atom is located above the center of a plane contain-
ing two P-donor and two S-donor atoms of the diphenyl-
phosphanylthiophenolato ligands arranged in mutual
trans-positions. The P-donor atom of trimethylphosphine
is located at the apical point of the pyramid.
Ph
Ph
PPh2
PMe3
P
CoMe(PMe )
+
Co
3
4
PMe3
PMe3
PMe3, CH4
SH
S
16
Regarding all information obtained from this compli-
cated reaction system (Eqs. (1) and (2)) a mechanism is
proposed as given in Scheme 1. In the first step the phenoxy
O-donor of the 2-acylphenolato chelating ligand in com-
plexes 1–5 is substituted by a (2-diphenylphosphanyl)thio-
phenolato chelating ligand leading to an intermediate
hydridocobalt complex 18. In the presence of trimethyl-
phosphine, 18 undergoes a reductive elimination to generate
the [P,S]-chelate cobalt(I) complex 16 with liberation of a
b-hydroxy aldehyde. Subsequently, hydrogen is evolved
from the acyl(hydrido)cobalt(III) complexes 1–5 and the
b-hydroxy aldehyde to afford the bis-chelate cobalt(III)
complexes 11–15. Disproportionation of complex 16 gives
rise to the bis-chelate complex 17 and tetrakis(trimethyl-
phosphine)cobalt(0). In a parallel reaction of complexes
1–5 with 2-diphenylphosphanylthiophenol the bis-chelate
complexes 6–7 are formed with evolution of hydrogen.
ð7Þ
Ph
P
+
Ph
Co
PPh2
SH
PMe3
CoX(PMe )
+
3
3
PMe3
PMe3
PMe3
SH
X = Cl, Br
ð8Þ
Ph
Ph
PMe3
P
Et N, PMe
+
3
3
Co
X
PMe3
PMe3
[Et3NH]X
S
16
At the same time a penta-coordinate cobalt(II) complex
with two [P,S]-chelating ligands (17) was also isolated from
the mother liquor in small amount as tiny brown-yellow
PMe3
OH
O
S
SH
H
O
O
R
Co
PMe3
Co
+
H
PPh2
PPh2
PMe3
R
PMe3
PMe3
PMe3
1-5
18
O
PMe
+
3
H2
H
PMe3
+
R
OH
Ph
O
O
PMe3
Co
H
Ph
Ph
PMe3
O
Ph
Co
P
S
Me3P
O
PMe3
P
Co
R
R
PMe3
PMe3
S
O
PMe3
O
R
cis-(11-15)
16
6-7, (8)-(10)
+
PMe3
PMe3
H
O
Ph
Ph
PMe3
O
S
P
Co
R
Co
(1/2)
R
O
Co(PMe4)4
O
P
S
PMe3
Ph
17
Scheme 1. A proposed mechanism of reaction of acyl(hydrido)cobalt(III) complexes with (2-diphenylphosphanyl)thiophenol.
Ph
trans-(11-15)

860
H. Sun et al. / Polyhedron 27 (2008) 854–860
O
Ph
Ph
P
PMe3
O
O
O
O
O
PMe3
Co
PMe3
Co
Ph
Ph
N
P
O
Co
>
>
O
O
O
S
R
R
R
R
R
R
PMe3
PMe3
PMe3
Ph
O
Ph
Ph
Ph
N
P
P
O
Co(PMe3)3
Co(PMe3)3
>
>
Co(PMe3)3
S
O
O
Scheme 2. Influence of chelating ligands containing hard/soft donor atoms on the stability of cobalt complexes.
According to the earlier work of Klein [1–5] and Sun [8],
Coordination of chelating ligands at Co(III) decreases as
when reacting an acyl(hydrido)cobalt(III) complex with 2-
nitrophenol and (2-diphenylphosphanyl)phenol, respec-
tively, to form cobalt(III) complexes with chelating 2-nitro-
phenolato ligands, in the light of the HSAB rule, the hard/
hard product is expected to be more stable than the hard/
soft product with (2-diphenylphosphanyl)phenolato
ligands. In combination with our present work, the influ-
ence of chelating ligands containing hard/soft donor atoms
on the relative stabilities of cobalt complexes can be
described as in Scheme 2. In the reaction system with 2-
nitrophenol the stable 2-acylphenolato cobalt(III) complex
was obtained, while a corresponding cobalt(I) complex
could not be experimentally verified [8]. In the present
work, the cobalt(I) complex 16 was isolated in high yield,
while relatively low yields were attained for complexes 6–
7 and 8–10. Derivatives of salicylaldehyde released in situ
react with starting materials to generate bis-chelate cobal-
t(III) complexes 11–15, and no formation of salicylalcohol
was observed, while salicylalcohol was identified in the
reaction system with (2-diphenyl)phosphanylphenol [8].
This result confirms the key role of (2-diphenylphospha-
nyl)phenol in the formation of salicylalcohol.
[N,O] > [P,O] > [P,S], while at Co(I) this order is reversed,
which is in accord with the HSAB rule.
Acknowledgements
We gratefully acknowledge support by NSFC China
No. 20572062. The Doctoral Program of Ministry of Edu-
cation of China (MOE) Nos. 20050422010, 20050422011,
Natural Science Foundation of Shandon No. Y2006B18
and Shandong Scientific Plan No. 032090105. We also
thank the kind assistance from Prof. Dieter Fenske for
the X-ray diffraction analysis.
Appendix A. Supplementary material
CCDC 641640 contains the supplementary crystallo-
graphic data for 17. These data can be obtained free of
charge
via
http://www.ccdc.cam.ac.uk/conts/retriev-
ing.html, or from the Cambridge Crystallographic Data
Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax:
(+44) 1223-336-033; or 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.poly.2007.
11.010.
4. Conclusions
References
The reaction of acyl(hydrido)cobalt(III) complexes 1–5
with (2-diphenylphosphanyl)thiophenol generated two
types of chelate cobalt(III) complexes (6–7, 8–10 and 11–
15), one chelate cobalt(I) complex (16) and one chelate
cobalt(II) complex (17). Complex 16 bearing a soft/soft
[P,S]-chelate ligand and a soft low-valent cobalt(I) central
atom was obtained in the highest yield of about 30–40%,
while the expected products with a soft/soft [P,S]-chelate
ligand and a hard high-valent cobalt(III) central atom (6,
7 and 8–10) show low yields (less than 10%). The by-prod-
ucts 11–15 with a hard/hard [O,O]-chelating ligand and a
hard cobalt(III) center are very stable. Cobalt(II) complex
17 could be separated as a result of a disproportionation
reaction of complex 16. A possible mechanism is proposed.
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