Reaction of 2-nitrophenols with high-valent trimethylphosphine complexes of cobalt

Article abstract of DOI:10.1016/S0020-1693(02)01138-6

Acylphenolato(hydrido)cobalt(III) complexes Co(η²-CO,O)H(PMe₃)₃ (CO,O=1-carbonyl-2-oxo-5-tert-butyl-cyclohexendiyl; 1-carbonyl-2-oxo-cyclohexendiyl) by reaction with 2-nitrophenol eliminate dihydrogen and are converted to 2-nitrophenolatocobalt(III) compounds. With the former dianionic ligand an intermediate tris(phosphine) compound 1 containing a η¹-nitrophenolato group is shown to adopt a meridional configuration in the crystal. In solution a η²-nitrophenolato coordination mode is usually attained after dissociation of one of the trimethylphosphines resulting in cis and trans isomers of bis(phosphine) compounds 2 and 3. bis(Phosphine) complexes 5-7 (cis, trans) were also obtained from Co(η²-CO,O)H(PMe₃)₃ (CO,O-1-carbonyl-2-oxo-3,4-benzo-cyclohexendiy1; 1-carbonyl-2-oxo-1,2-diphenyl-ethendiyl) and 2-nitronaphthol. No reduction of nitro groups neither by free PMe₃ nor by excess CoH complex was observed although the corresponding nitrosonaphtholato complexes 8 and 9 were readily formed upon combining Co(η²-CO,O)H(PMe₃)₃(CO,O=1-carbonyl-2- oxo-5-tert-butyl-cyclohexendiyl; 1-carbonyl-2-oxo-1,2-diphenyl-ethendiyl) and 2-nitrosonaphthol.

Full text of DOI:10.1016/S0020-1693(02)01138-6

Inorganica Chimica Acta 342 (2003) 179ꢂ184
/
www.elsevier.com/locate/ica
Reaction of 2-nitrophenols with high-valent trimethylphosphine
complexes of cobalt
Hans-Friedrich Klein a,ꢀ, Xiaoyan Li a, Ulrich Florke b, Hans-Jurgen Haupt b
¨
¨
a Eduard-Zintl-Institut fu¨r Anorganische und Physikalische Chemie der Technischen Universita¨t Darmstadt, Petersenstraße 18, D-64287 Darmstadt,
Germany
b Anorganische und Analytische Chemie der Universita¨t Paderborn, Warburger Straße, D-33098 Paderborn, Germany
Received 20 February 2002; accepted 25 May 2002
Abstract
Acylphenolato(hydrido)cobalt(III) complexes Co(h2-CO,O)H(PMe3)3 (CO,Oꢁ
/1-carbonyl-2-oxo-5-tert-butyl-cyclohexendiyl; 1-
carbonyl-2-oxo-cyclohexendiyl) by reaction with 2-nitrophenol eliminate dihydrogen and are converted to 2-nitrophenolatoco-
balt(III) compounds. With the former dianionic ligand an intermediate tris(phosphine) compound 1 containing a h1-nitrophenolato
group is shown to adopt a meridional configuration in the crystal. In solution a h2-nitrophenolato coordination mode is usually
attained after dissociation of one of the trimethylphosphines resulting in cis and trans isomers of bis(phosphine) compounds 2 and
3. bis(Phosphine) complexes 5ꢂ
7 (cis, trans) were also obtained from Co(h2-CO,O)H(PMe3)3 (CO,O-1-carbonyl-2-oxo-3,4-benzo-
cyclohexendiy1; 1-carbonyl-2-oxo-1,2-diphenyl-ethendiyl) and 2-nitronaphthol. No reduction of nitro groups neither by free PMe3
/
nor by excess CoH complex was observed although the corresponding nitrosonaphtholato complexes 8 and 9 were readily formed
upon combining Co(h2-CO,O)H(PMe3)3(CO,Oꢁ
ethendiyl) and 2-nitrosonaphthol.
/1-carbonyl-2-oxo-5-tert-butyl-cyclohexendiyl; 1-carbonyl-2-oxo-1,2-diphenyl-
# 2002 Elsevier Science B.V. All rights reserved.
Keywords: Cobalt(III) complexes; Trimethylphosphine; Acylenolato; 2-Nitrophenolato ligands; Crystal structures
1. Introduction
2. Experimental
2.1. General procedures and materials
Reduction of 2-nitrophenols by trimethylphosphine
complexes of cobalt in low formal oxidation states is a
multistep process [1] where several species can act as
reducing agents. Dissociation of ligands enhances the
reactivity of the low-valent metal center towards elec-
tron acceptor molecules and provides reducing equiva-
lents by forming trimethylphosphine oxide. 2-
Nitrophenols can be precoordinated as chelating ligands
Standard vacuum techniques were used in manipula-
tions of volatile and air-sensitive material. Details of
characterization and spectroscopic instrumentation have
been given elsewhere [2]. tetrakis(Trimethylphosphine)-
cobalt methyltetrakis(trimethylphosphine)cobalt [3],
chlorotris(trimethylphosphine)cobalt [4], and 2-acylphe-
nolatocobalt compounds [5] were prepared by published
procedures.2-Nitrophenol,2-nitro-1-naphthol,2-nitroso-
generating a Coꢀ/H function and subsequently undergo
a stepwise transformation to anionic nitroso-, amido-,
and imido-phenolato ligands depending on the metal,
the metal hydride, and the metal trimethylphosphine
functionalities. An experimental distinction between
metal oxidation state and reducing functionalities was
attempted in order to establish the actual source of the
reduction equivalents.
1-naphthol (Merckꢂ/Schuhardt) were used as purchased.
2.2. Procedures
2.2.1. Synthesis of mer-(1-carbonyl-2-oxo-5-tert-butyl-
cyclohexene-diyl)(2-
nitrophenolato)tris(trimethylphosphine)cobalt(III) (1)
A sample containing 0.70 g of mer-hydrido(1-carbon-
yl-2-oxo-5-tert -butyl-cyclohexene-diyl)tris(trimethyl-
ꢀ Corresponding author. Tel.: ꢃ
/
49-6151-162 173; fax: ꢃ49-6151-
/
164 173
0020-1693/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 0 - 1 6 9 3 ( 0 2 ) 0 1 1 3 8 - 6

180
H.-F. Klein et al. / Inorganica Chimica Acta 342 (2003) 179ꢂ
/
184
1
phosphine)cobalt(III) (1.49 mmol) and 0.22 g of 2-
nitrophenol (1.58 mmol) in 20 ml of ether after 20 h at
20 8C formed a red solution. The volatiles were
removed in vacuo, and the resulting solid was extracted
j J(PC)ꢃ3
/
J(PC)jꢁ
/
24.0 Hz, PCH3), 22.7, 30.1 (CH2),
112.9, 125.1, 128.2, 133.1) (CH).31P NMR (81.0 MHz,
THF-d8, 233 K) for cis-4: d 20.0 (s(br)); 25.5 (s(br)).
Compound cis-4: d 13.2 (s).
with pentane over a glass-sinter disc (G3). Cooling to ꢄ
/
27 8C overnight afforded light brown cubes which were
isolated by decantation and drying in vacuo at 20 8C
2.2.3. Synthesis of 1-carbonyl-2-oxo-3,4-benzo-
cyclohexene-diyl)(2-nitro-1-
(0.63 g, 70%), dec.ꢀ
/
140 8C.
naphtholato)bis(trimethylphosphine)cobalt(III) (5)
A sample containing 1.20 g of mer-hydrido(1-carbon-
yl-2-oxo-3,4-benzo-cyclohexene-diyl)tris(trimethylpho-
sphine)cobalt(III) (2.61 mmol) and 0.52 g of 2-nitro-1-
naphthol (2.75 mmol) in 20 ml of ether after 2 days at
20 8C formed a dark red solution from which a red
solid was deposited. The volatiles were removed in
vacuo, and the resulting solid was washed with pentane
Anal. Calc. for C26H47CoNO5P3 (605.5): C, 51.57; H,
7.82; N, 2.31; P, 15.34. Found: C, 51.06; H, 8.01; N,
2.31; P, 15.86%.
IR (Nujol mull, 2600ꢂ
/
1570 cmꢄ1): 1612m, n(Nꢁ
O). H NMR (300 MHz, THF-d8, 297 K)
/
O);
1
1595s, n(Cꢁ
/
for 1/cis-2/trans-2ꢁ63/29/7. Compound 1: d 0.91 (s,
/
9H, CCH3), 1.24 (t?, j J(PH)ꢃ4
/
J(PH)jꢁ
/
7.9 Hz, 18H,
9.3 Hz, 9H, PCH3), 6.05 (dt,
2
2
PCH3), 1.38 (d, J(PH)ꢁ
/
and extracted with ether. Crystallization at ꢄ
afforded dark red microcrystals (1.23 g, 82%), dec.ꢀ
183 8C.
Anal. Calc. for C27H32CoNO5P2 (571.4): C, 56.75; H,
/
27 8C
3J(HH)ꢁ
3J(HH)ꢁ
3J(HH)ꢁ
/
8.7 Hz, 4J(HH)ꢁ
/
1.1 Hz, CH), 7.26 (dd,
2.0 Hz, CH), 7.63 (dd,
0.9 Hz, CH). Compound
/
/
8.0 Hz, 4J(HH)ꢁ
/
4
/
8.7 Hz, J(HH)ꢁ
/
2
cis-2: d 0.89 (s, 9H, CCH3), 1.07 (dd, J(PH)ꢁ
/
6.7 Hz,
10.6
1.9 Hz, 9H, PCH3), 1.28 (dd, J(PH)ꢁ
10.6 Hz, J(PH)ꢁ1.6 Hz, 9H, PCH3), 6.23ꢂ7.86 (m,
CH). Without assignment: d 1.81ꢂ
2.50 (m, CH2). 13C
NMR (75.4 MHz, THF-d8, 297 K): d 13.2 (m, PCH3),
5.64; N, 2.45; P, 10.84. Found: C, 57.55; H, 5.78; N,
2.51; P, 11.34%.
4J(PH)ꢁ
Hz, J(PH)ꢁ
/
1.3 Hz, 9H, PCH3), 1.15 (dd, J(PH)ꢁ
/
2
4
2
/
/
IR (Nujol mull, 2600ꢂ
1601s, n(Cꢁ
O). 1H NMR (300 MHz, acetone-d6, 297 K)
cis-5/trans-5ꢁ67/33. Compound cis-5: d 1.26 (d,
2J(PH)ꢁ
11.0 Hz, 9H, PCH3), 1.44 (d, J(PH)ꢁ
/
1570 cmꢄ1): 1615s, n(Nꢁ
/
O);
4
/
/
/
/
/
2
/
/
11.0
8.27 (m, CH). Compound trans-5:
14.1 Hz, 18H, PCH3)
2.80
1
14.5 (m, PCH3) 16.8 (d, J(PC)ꢁ
/
25.3 Hz, PCH3), 25.5
Hz, 9H, PCH3) 6.73ꢂ
/
2
(s, CH2), 26.1 (s, CH2), 27.9 (s, CCH3), 32.9 (s, CCH3),
33.7 (s, CH2), 46.6 (s, CH), 109.2 (CH), 111.2 (s, CCO);
124.9, 126.0, 132.5 (CH), 188.4 (CCO). 31P NMR (81.0
MHz, THF-d8, 233 K) for 1: d 17.8 (s(br)); for 2: d 13.2
d 1.13 (t?, j J(PH)ꢃ4
/
J(PH)jꢁ
/
6.77ꢂ
/
8.23 (m, CH). Without assignment: d 2.40ꢂ
/
(m, CH2). 31P NMR (81.0 MHz, acetone-d6, 233 K) cis-
5: d 21.7 (s(br)); trans-5: d 12.9 (s).
(s(br)). For free P(CH3)3: d ꢄ56.0 (s).
/
2.2.4. Synthesis of (1-carbonyl-2-oxo-cyclohexene-
diyl)(2-nitro-1-
2.2.2. Synthesis of (1-carbonyl-2-oxo-cyclohexene-
diyl)(2-
naphtholato)bis(trimethylphosphine)cobalt(III) (6)
A sample containing 1.20 g of mer-hydrido(1-carbon-
yl-2-oxo-cyclohexene-diyl)tris(trimethylphosphine)co-
balt(III) (2.91 mmol) and 0.53 g of 2-nitro-1-naphthol
(2. 80 mmol) in 60 ml of ether after 20 h at 20 8C
formed a dark red solution from which a red solid
precipitated. The volatiles were removed in vacuo, and
the resulting solid was washed with pentane and
nitrophenolato)bis(trimethylphosphine)cobalt(III) (4)
A sample containing 1.70 g of mer-hydrido(1-carbon-
yl-2-oxo-cyclohexene-diyl)tris(trimethylphosphine)co-
balt(III) (4.12 mmol) and 0.65 g of 2-nitrophenol (4.67
mmol) in 60 ml of ether after 3 days at 20 8C formed a
dark red solution. The volatiles were removed in vacuo,
and the resulting solid was washed with pentane and
extracted with ether. Crystallization at ꢄ
/
27 8C af-
extracted with ether. Keeping the solution at ꢄ
overnight afforded dark red microcrystals (1.10 g. 75%),
dec.ꢀ178 8C.
Anal. Calc. for C23H32CoNO5P2 (523.4): C, 52.78; H,
6.16; N, 2.67; P, 11.83. Found: C, 53.60; H, 6.25; N,
2.67; P, 11.95%.
/
27 8C
forded red cubes (1.40 g, 72%), dec.ꢀ 158 8C.
/
Anal. Calc. for C19H30CoNO5P2 (473.3): C, 48.21; H,
6.39; N, 2.96; P, 13.09. Found: C, 48.39; H, 6.40; N,
2.89; P, 12.39%.
/
IR (Nujol mull, 2600ꢂ
/
1570 cmꢄ1): 1632s, n(Nꢁ
O). H NMR (300 MHz, THF-d8, 297 K)
cis-4/trans-4ꢁ78/22. Compound cis-4: d 1.15 (d,
2J(PH)ꢁ10.6 Hz, 9H, PCH3), 1.28 (d, 2J(PH)ꢁ
9.3
7.73 (m, CH). Compound trans-4:
8.2 Hz, 18H, PCH3),
/O);
1
1607s n(Cꢁ
/
IR (Nujol mull, 2600ꢂ
/
l570 cmꢄ1): 1623s, n(Nꢁ
O). H NMR (300 MHz, THF-d8, 297 K)
cis-6/trans-6ꢁ69/31. Compound cis-6: d 1.20 (d,
2J(PH)ꢁ
10.8 Hz, 9H, PCH3), 1.32 (d, J(PH)ꢁ
8.27 (m, CH), trans-6: d 1.06(t?,
8.3 Hz, 18H, PCH3), 6.65ꢂ8.19 (m,
2.58 (m, CH2). 31P
59/
41. cis-6: d 20.6 (s(br)); 26.4 (s(br)); trans-6: d 13.7 (s).
/
O);
1
/
1609s, n(Cꢁ
/
/
/
/
2
Hz, 9H, PCH3), 6.23ꢂ
/
/
/
10.4
2
d 1.08 (t?, j J(PH)ꢃ4
/
J(PH)jꢁ
/
Hz, 9H, PCH3), 6.65ꢂ
/
2
6.23ꢂ
/
7.85 (m, CH). 13C NMR (75.4 MHz, THF-d8, 297
j J(PH)ꢃ4
/
J(PH)jꢁ
/
/
K). Compound cis-4: d 11.4 (m, PCH3), 22.8, 31.5
(CH2), 103.6 (CCO) 120.0, 125.0, 127.5, 133.5 (CH),
169.3, 189.4 (CCO). Compound trans-4: d 8.4 (t?,
CH). Without assignment: d 1.93ꢂ
/
NMR (81.0 MHz, THF-d8, 233 K) cis-6/trans-6ꢁ
/

H.-F. Klein et al. / Inorganica Chimica Acta 342 (2003) 179ꢂ
/
184
181
2.2.5. Synthesis of (1-carbonyl-2-oxo-1,2-
2.2.6. Synthesis of (1-carbonyl-2-oxo-5-tert-butyl-
cyclohexene-diyl)(2-nitroso-1-
naphtholato)bis(trimethylphosphine)cobalt(III) (8)
diphenylethene-diyl)(2-nitro-1-
naphtholato)bis(trimethylphosphine)cobalt(III) (7)
A sample containing 0.80 g of mer-hydrido(1-carbon-
yl-2-oxo-1,2-diphenylethene-diyl)tris(trimethylphosphi-
ne)cobalt(III) (1.57 mmol) and 0.33 g o f 2-nitro-1-
naphthol (1.74 mmol) in 80 ml of ether after 22 h at
20 8C formed a dark red solution. The volatiles were
removed in vacuo, and the resulting solid was washed
with pentane and extracted with ether. Crystallization at
A sample containing 1.30 g of mer-hydrido(1-carbon-
yl-2-oxo-5-tert -butyl-cyclohexene-diyl)tris(trimethyl-
phosphine)cobalt(III) (2.78 mmol) and 0.56 g of 2-
nitroso-1-naphthol (3.23 mmol) in 40 ml of ether after
18 h at 20 8C formed a dark brown solution from which
a black solid was precipitated. The volatiles were
removed in vacuo, and the resulting solid was washed
with pentane and extracted with toluene. Crystallization
ꢄ
/
27 8C afforded dark red microcrystals (0.76 g, 78%),
at ꢄ
dec.ꢀ
/
27 8C afforded black microcrystals (1.28 g, 60%),
180 8C.
dec.ꢀ190 8C.
/
/
Anal. Calc. for C31H34CoNO5P2 (621.5): C, 59.91; H,
5.51; N, 2.25, Found: C, 59.86; H, 5.58; N, 2.08%.
Anal. Calc. for C31H34CoNO4P2 (605.5): C, 61.49; H,
5.66; N, 2.31. Found: C, 62.06; H 5.95; N, 2.21%.
IR (Nujol mull, 2600ꢂ
/
1570 cmꢄ1): 1616s, n(Nꢁ
/
O):
O). H NMR (300 MHz, THF-d8, 297 K)
cis-7/trans-7ꢁ90/10. Compound cis-7: d 1 35 (d,
2J(PH)ꢁ10.8 Hz, 9H PCH3), 1.40 (d, 2J(PH)ꢁ
10.8
8.36 (m CH), trans-7, d 1.17 (t?,
8.5 Hz, 18H PCH3), 6.70ꢂ8.26 (m,
1
IR (Nujol mull, 2600ꢂ
/
1570 cmꢄ1): empty. H NMR
1
1598s n(Cꢁ
/
2
(200 MHz, THF-d8; 297 K): d 1.40 (d, J(PH)ꢁ
/10.2
/
Hz, 18H, PCH3,) 7.20ꢂ/9.70 (m, 16H, CH).
/
/
Hz, 9H, PCH3), 6.74ꢂ
/
2
2.2.7. X-ray crysta1 measurements
j J(PH)ꢃ4
/
J(PH)jꢁ
/
/
Crystal structure analyses: crystal data for com-
pounds 1 and cis-6 are presented in Table 1. Data
collection with single crystals scaled in glass capillaries
under argon and mounted on a Siemens P4 diffract-
CH). 31P NMR (81.0 MHz, THF-d8, 233 K) cis-7: d
2
2
20.4 (d, J(PP)ꢁ
/
80.0 Hz), 27.1 (d, J(PP)ꢁ80.0 Hz),
/
trans-7: d 14.6 (s).
ometer, graphite monochromated Mo Ka radiation,
Table 1
Crystal data and refinement details for 1 and cis-6
˚
0.71073 A, v-scans, Lp corrections and empirical
lꢁ
/
absorption corrections via psi-scans applied. Structure
solutions with direct and conventional Fourier methods;
full-matrix least-squares refinement based on F2, all
non-hydrogen atoms refined anisotropically, hydrogen
atoms with riding model at idealized positions with
1
cis-6
Formula
C
605.5
26H47CoNO5P3
C23H32CoNO5P2
523.4
Molecular mass
Crystal size (mm)
Crystal system
Space group
0.65ꢅ0.37ꢅ0.12
monoclinic
P21/n
0.30ꢅ0.24ꢅ0.22
monoclinic
P21/c
Uiso
C52 atoms with split model and site occupation factors
0.50 each, disordered methyl groups C91ꢀC111 and
C92ꢀC112 with split model and s.o.f. 0.672(8); for cis-6
disordered C41ꢀC51 and C42ꢀC52 with split model and
0.001. Programs used:
ꢁ
/
1.2U(C) and 1.5U(Cmethyl); for 1 disordered C51/
˚
a (A)
13.908(3)
12.132(3)
19.626(3)
108.91(2)
3132.8(15)
4
14.769(3)
9.787(1)
/
˚
b (A)
/
c (A)
b (8)
˚
V (A)
18.123(2)
104.77(1)
2533.0(6)
4
/
/
s.o.f. 0.52(2)/0.48(2); max(D/s)B
/
Z
SHELXTL [6].
Dcalc (g cmꢄ3
)
1.284
0.734
1.372
0.836
m (Mo Ka) (mmꢄ1
Temperature (K)
Data collection
range (8)
)
293(2)
2.195u 527.00
293(2)
2.325u 527.50
3. Results and discussion
Limiting indices
ꢄ175h 51,
ꢄ155k 51,
ꢄ245l 525
8411
ꢄ195h 51,
ꢄ15k 512,
ꢄ235l 523
7215
Among the reducing species which are supplied or
subsequently generated in the alkyl/metal/trimethylpho-
sphine system acting on 2-nitrophenols we have to
distinguish between
Number of reflec-
tions measured
Number of unique
data
6840 (Rintꢁ0.0353)
5804 (Rintꢁ0.0563)
a) free or coordinated trimethylphosphine being oxi-
dized by the nitrophenol:
Parameters
Goodness-of-fit
on F2
322
1.012
289
0.943
RꢀNO2 ꢃMe3P 0 RꢀNOꢃMe3PꢁO
b) the metal center in a low formal oxidation state, e.g.
RꢀNO2 ꢃCo(I) 0 RꢀNOꢃCo(III)O
R1 (I ꢀ2s(I))
R1 (all data)
wR2 (all data)
0.0590
0.1213
0.1599
0.413
0.0646
0.1748
0.1365
0.304
ꢄ3
˚
Drmax (e A
)
ꢄ3
˚
Drmin (e A
)
ꢄ0.164
ꢄ0.334
c) the metal center being protonated by the phenol and
turning out a metal hydride function through

182
H.-F. Klein et al. / Inorganica Chimica Acta 342 (2003) 179ꢂ184
/
oxidative addition:
RꢀNO2 ꢃCoꢀH 0 RꢀNOꢃCoꢀOH
An experimental distinction between adventitious
and active reducing agents in the system became
possible as acylphenolato(hydrido)cobalt(III) com-
plexes [5] were found to smoothly react with 2-
nitrophenols, in a first step according to Eq. (1).
Fig. 1. Molecular structure of 1, only major part of disordered regions
˚
shown; selected distances (A) and angles (8): Co1ꢀ
O2 1.956(3), Co1ꢀO3 2.089(3), Co1ꢀP1 2.2450(15), Co1ꢀ
2.2527(14), Co1ꢀP3 2.2206(12), O1ꢀC1 1.230(4), O2ꢀC7 1.300(4),
O3ꢀC12 1.302(4), O4ꢀN1 1.205(5), O5ꢀN1 1.200(5), N1ꢀC13 1.451
(6), C2ꢀC7 1.354(5); C1ꢀCo1ꢀO3 178.16(15), P2ꢀCo1ꢀP3 94.08(5),
P1ꢀCo1ꢀP2 170.04(5), C12ꢀO3ꢀCo1 139.7(3), C1ꢀCo1ꢀO2
84.80(14), C7ꢀO2ꢀCo1 110.5(2), C1ꢀC2ꢀC7 113.4(4), O2ꢀC7ꢀC2
121.2(4), C2ꢀC1ꢀCo1 110.1(3).
/
C1 1.917(4), Co1ꢀ
/
/
/
/
P2
/
/
/
/
/
/
/
ð1Þ
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
The 2-nitrophenolatocobalt(III) complex 1 forms
yellow brown cubic crystals (from pentane) which are
air-stable and decompose above 40 8C. In the IR
/
/
The molecular structure of 1 (Fig. 1) shows a
hexacoordinate cobalt and three P-donor atoms lying
in a plane, and two phenolato-O donors and an acyl
group are arranged in a plane perpendicular to the first.
spectra the conspicuous n(Coꢀ
/
H) absorption of the
starting complex is absent. The 1H NMR spectrum
indicates the presence of 1 by the expected pattern of
PCH3 signals as a virtual triplet for two trans-phos-
phines and a doublet for the singular PMe3 ligand. A
multitude of further resonances indicates a mixture of
isomers in solution resulting from an equilibration
reaction according to Eq. (2).
In opposite position to the acyl group the Cꢀ
/
O distance
˚
2.089(3) A) is larger than that opposite to a
(Co1ꢀ
/
O3ꢁ
/
˚
O2ꢁ1.956(3) A) indicating a
trimethylphosphine (Co1ꢀ
/
/
strong trans-influence in the former. There is some
positional disorder at C51 (50%) and C52 (50%) as well
as rotational disorder of the tert-butyl group with site
occupation of 67 and 33% and to a lesser extent in the
NO2 group which is rotated out of the phenolic ring
plane.
Dimensions in the chelate ring are normal, and the
sum of internal angles (540.08) is as expected for a
planar five-membered metallocycle. Without a tert-
ð2Þ
Although assignment was not unequivocally possible
for all three complexes, 31P data clearly show three
signals for coordinated trimethylphosphine, one at 17.8
ppm for 1 (63%) and two broad resonances at 13.2 (29%
cis-2) and 25.8 ppm (7% trans-2). An additional sharp
resonance appeared at ꢄ
trimethylphosphine is expected.
/
56.0 ppm where uncoordinated
ð3Þ

H.-F. Klein et al. / Inorganica Chimica Acta 342 (2003) 179ꢂ
/
184
183
butyl substituent and after prolonged reaction times a
tris(phosphine) intermediate similar to 1 is not found.
Loss of 1 equiv. of trimethylphosphine smoothly gives a
mixture of isomers cis-4 (68%) and trans-4 (32%) in 72%
yield according to Eq. (3).
The dark red crystals of 4 are stable up to 158 8C and
can be handled in air for several days without any sign
of decomposition. Well-resolved 1H and 31P NMR
spectra clearly show the presence of two isomers cis-4
(78%) and trans-4 (22%) in THF solution. Analogous
reactions have been carried out with 2-nitronaphthol
and three acylenolato(hydrido)cobalt complexes accord-
ing to Eq. (4).
Fig. 2. Molecular structure of cis-6, only major part of disordered
˚
regions shown; selected distances (A) and angles (8): Co1ꢀ
Co1ꢀO2 1.929(3), Co1ꢀO3 1.931(3), Co1ꢀO4 2.110(3), Co1ꢀ
2.2223(16), Co1ꢀP2 2.1798(15), C1ꢀO1 1.224(5), O4ꢀN1 1.268(4),
O5ꢀN1 1.235(4); P1ꢀCo1ꢀP2 96.51(6), C1ꢀCo1ꢀO4 170.86(19), O3ꢀ
Co1ꢀO4 86.07(13), C8ꢀO3ꢀCo1 127.2(3), O3ꢀC8ꢀC17 127.3(5), C8ꢀ
C17ꢀN1 123.0(4), C17ꢀN1ꢀO4 121.4(4), N1ꢀO4ꢀCo1 123.9(3).
/
C1 1.925(5),
/
/
/
/
P1
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
ð4Þ
phines at different bonding distances. The shorter
˚
(Co1ꢀ
/
P2ꢁ2.180(2) A) is opposite to the weaker O-
/
donor atom of the naphtholato group, and the longer
˚
P1ꢁ2.222(2) A) is subject to the influence of the
(Co1ꢀ
/
/
stronger phenolato donor. The spiro metal atom is part
of a planar five-membered and a perpendicular six-
membered chelate ring which adopts a boat conforma-
tion. Both the cis and trans complex configurations
place the acyl-C and nitro-O donors in opposite posi-
tions as expected for an optimum balance of trans-
influences.
Under the conditions of syntheses the nitrophenola-
tocobalt(III) compounds 1ꢂ7 are unreactive towards
/
trimethylphosphine or excess of the hydridocobalt(III)
educt. Reduction equivalents carried by those groups
are not utilized. The corresponding 2-nitroso com-
pounds were shown to be thermally stable target
complexes by reaction according to Eq. (5).
Black microcrystals of 8 or 9 were obtained in 60%
yield that decompose above 240 and 180 8C, respec-
tively. Spectroscopic data are as expected for 2-nitroso-
naphtholato-1-cobalt complexes, and because of the low
solubility in THF no attempts were made to further
elucidate the mixtures of cis and trans isomers. Again
no reduction to the imido or amido stage was observed
which could proceed by subsequent reactions either with
the liberated trimethylphosphine or with excess starting
complex.
Again cis and trans isomers were observed by NMR
spectroscopy in THF solutions. A dark red crystal of 6
was examined by X-ray diffraction and shown to consist
of molecular units cis-6.
The molecular structure Fig. 2 contains an octahed-
rally coordinated cobalt(III) center with two cis-phos-

184
H.-F. Klein et al. / Inorganica Chimica Acta 342 (2003) 179ꢂ184
/
deposited as supplementary material with the Cam-
bridge Crystallographic Data Centre. Deposition num-
bers are CCDC-177639 for 1 and 177640 for cis-6.
Copies of the data can be obtained free of charge on
application to CCDC, 12 Union Road, Cambridge, CB2
1EZ, UK (fax:ꢃ44-1223-336-033; e-mail: deposit@
/
ccdc.cam.ac.uk or www:http://www.ccdc.cam.ac.uk).
(5)
Acknowledgements
Financial support of this work by Deutsche Forse-
hungsgemeinschaft (SP ‘Nitridobruecken’) is gratefully
acknowledged.
References
[1] H.-F. Klein, A. Dal, S. Hartmann, U. Florke, H.-J. Haupt, Inorg.
¨
Chim. Acta 287 (1999) 199.
[2] H.-F. Klein, A. Petermann, Inorg. Chim. Acta 261 (1997) 187.
[3] H.-F. Klein, H.H. Karsch, Chem. Ber. 108 (1975) 944.
[4] H.-F. Klein, H.H. Karsch, Inorg. Chem. 14 (1975) 473.
[5] H.-F. Klein, S. Haller, H. Sun, X. Li, T. Jung, C. Rohr, U. Florke,
¨ ¨
4. Supplementary material
H.-J. Haupt, Z. Naturforsch., Teil B 53 (1998) 587.
[6] Siemens SHELXTL, Ver. 5.1. Siemens Analytical X.ray Instruments
Inc., Madison, WI, USA.
Crystallographic data (without structure factors) for
the structures described in this publication have been