Insertion reactions of (benzyne)nickel(0) complexes with carbon monoxide: X-ray structure of a (phthalato)nickel(II) complex formed by oxidation of an η1:η1-phthaloyl intermediate

Article abstract of DOI:10.1021/om950699v

The reaction of (benzyne)nickel(0) complexes Ni(η²-C₆H₄)(dcpe) (1) and Ni((1,2-η)-4,5-F₂C₆H₂)(dcpe) (2) [dcpe = 1,2-bis(dicyclohexylphosphino)ethane, (C₆Hu)₂PCH₂CH₂P(C₆H ₁₁)₂] with carbon monoxide at low concentration gives Ni(CO)₂(dcpe) (3) and, as the main organic products, 9H-fluoren-9-one (4) and 2,3,6,7-tetrafluoro-9H-fluoren-9-one (5), 2,3,6,7-X₄C₁₂H₄-CO (X = H, F), respectively, resulting from monoinsertion into the nickel-benzyne bond. Higher concentrations of CO give rise to bis(acyl) intermediates, one of which, Ni(CO-4,5-F₂C₆H₂CO-2)(dcpe) (9), has been observed by ³¹P and ¹⁹F NMR spectroscopy. These intermediates reversibly form 3 and the corresponding benzocyclobutenediones OC-4,5-X₂C₆H₂CO [X = H (12), F (13)] by reductive elimination and react readily with oxygen to form the stable (phthalato)nickel(II) complexes Ni(OCOC₆H₄COO-2)(dcpe) (6) and Ni(OCO-4,5-F₂C₆H₂COO-2)(dcpe) (7). On treatment with iodine, the latter give the corresponding phthalic anhydrides C₆H₄C₂O₃ (10) and 4,5-F₂C₆H₂C₂O₃ (11), respectively. According to a single-crystal X-ray study, 7 is a planar nickel(II) complex containing a seven-membered chelate ring with monodentate carboxylato groups, the average Ni-O and Ni-P distances being 1.904(4) and 2.152(2) A?, respectively.

Full text of DOI:10.1021/om950699v

928
Organometallics 1996, 15, 928-933
In ser tion Rea ction s of (Ben zyn e)n ick el(0) Com p lexes
w ith Ca r bon Mon oxid e: X-r a y Str u ctu r e of a
(P h th a la to)n ick el(II) Com p lex F or m ed by Oxid a tion of
a n η1:η1-P h th a loyl In ter m ed ia te
Martin A. Bennett,*,† David C. R. Hockless,† Mark G. Humphrey,‡
Madeleine Schultz,‡ and Eric Wenger‡
Research School of Chemistry and Department of Chemistry, Australian National University,
Canberra, ACT 0200, Australia
Received September 5, 1995X
The reaction of (benzyne)nickel(0) complexes Ni(η2-C6H4)(dcpe) (1) and Ni((1,2-η)-4,5-
F2C6H2)(dcpe) (2) [dcpe ) 1,2-bis(dicyclohexylphosphino)ethane, (C6H11)2PCH2CH2P(C6H11)2]
with carbon monoxide at low concentration gives Ni(CO)2(dcpe) (3) and, as the main organic
products, 9H-fluoren-9-one (4) and 2,3,6,7-tetrafluoro-9H-fluoren-9-one (5), 2,3,6,7-X4C12H4-
CO (X ) H, F), respectively, resulting from monoinsertion into the nickel-benzyne bond.
Higher concentrations of CO give rise to bis(acyl) intermediates, one of which, Ni(CO-4,5-
F2C6H2CO-2)(dcpe) (9), has been observed by 31P and 19F NMR spectroscopy. These
intermediates reversibly form 3 and the corresponding benzocyclobutenediones OC-4,5-
X2C6H2CO [X ) H (12), F (13)] by reductive elimination and react readily with oxygen to
form the stable (phthalato)nickel(II) complexes Ni(OCOC6H4COO-2)(dcpe) (6) and Ni(OCO-
4,5-F2C6H2COO-2)(dcpe) (7). On treatment with iodine, the latter give the corresponding
phthalic anhydrides C6H4C2O3 (10) and 4,5-F2C6H2C2O3 (11), respectively. According to a
single-crystal X-ray study, 7 is a planar nickel(II) complex containing a seven-membered
chelate ring with monodentate carboxylato groups, the average Ni-O and Ni-P distances
being 1.904(4) and 2.152(2) Å, respectively.
In tr od u ction
The insertion of carbon monoxide into nickel-carbon
σ-bonds to form nickel acyls is a key step in many
organic reactions catalyzed or promoted by Ni(CO)4.1,2
Acylnickel(II) complexes NiY(COR)L2 have been isolated
by carbonylation of mono(alkyl)nickel(II) complexes
NiY(R)L2 (R ) σ-alkyl; Y ) various monoanionic ligands;
L ) various tertiary phosphines).3 In contrast, carbo-
nylation of bis(alkyls) NiR2L2 gives Ni(CO)2L2 and
organic carbonyl compounds as a result of successive
mono- or diinsertions and subsequent reductive elimi-
nations. For example, NiMe2L2 gives 2,3-butanedione
and acetone in proportions that depend on the temper-
ature, pressure of CO, and the nature of L.4 Similarly,
nickelacycles react with CO to give cyclic ketones (eqs
1 and 2).5,6
Since nickel-carbon σ-bonded species are likely to be
intermediates in the Ni(CO)4-catalyzed formation of R,â-
unsaturated acids from alkynes, CO, and H2O,1,2,7 the
isolation of intermediates from the reaction of CO with
nickel-alkyne complexes has attracted interest. The
complexes Ni(η2-alkyne)(bipy) (alkyne ) PhC2H, PhC2-
Ph, MeC2Me; bipy ) 2,2′-bipyridine) undergo double
insertion of CO to give bis(acyl)nickel(II) complexes,
which reversibly eliminate the corresponding cyclobutene-
diones or form the corresponding anhydrides by reaction
with oxygen (Scheme 1).8-10
† Research School of Chemistry.
‡ Department of Chemistry.
X Abstract published in Advance ACS Abstracts, December 15, 1995.
(1) J olly, P. W.; Wilke, G. The Organic Chemistry of Nickel; Academic
Press: New York, 1975; Vol. 2; p 294.
The bonds in (benzyne)- and (naphthalyne)nickel(0)
complexes probably have considerable nickel-carbon
(2) J olly, P. W. In Comprehensive Organometallic Chemistry; Wilkin-
son, G.; Stone, F. G. A., Abel, E. W., Eds.; Pergamon: Oxford, U.K.,
1982; Vol. 8; p 773.
(3) J olly, P. W. In Comprehensive Organometallic Chemistry; Wilkin-
son, G., Stone, F. G. A., Abel, E. W., Eds.; Pergamon: Oxford, U.K.,
1982; Vol. 6, p 73 and references cited therein.
(4) Yamamoto, T.; Kohara, T.; Yamamoto, A. Bull. Chem. Soc. J pn.
1981, 54, 2161.
(5) Grubbs, R. H.; Miyashita, A.; Liu, M.; Burk, P. J . Am. Chem.
Soc. 1978, 100, 2418.
(7) Bird, C. W.; Briggs (ne´e Hollins), E. M. J . Chem. Soc. C 1967,
1265.
(8) Hoberg, H.; Herrera, A. Angew. Chem., Int. Ed. Engl. 1980, 19,
927.
(9) Hoberg, H.; Herrera, A. Angew. Chem., Int. Ed. Engl. 1981, 20,
876.
(10) Herrera, A.; Hoberg, H.; Mynott, R. J . Organomet. Chem. 1981,
222, 331.
(6) Hoberg, H.; Richter, W. J . Organomet. Chem. 1980, 195, 355.
0276-7333/96/2315-0928$12.00/0 © 1996 American Chemical Society

A (Phthalato)nickel(II) Complex
Organometallics, Vol. 15, No. 3, 1996 929
Sch em e 1
Sch em e 3
Sch em e 2
of five-line multiplets at δ -126.7 and -135.9. A small
amount of a compound having a triplet at δ -123.3 in
C6D6, probably 4,5-difluorophthalic anhydride, was also
present (see below).
When CO was added more rapidly to the (benzyne)-
nickel(0) solutions, e.g. by first evacuating and then
refilling with CO, the fluorenones were still formed, but
other compounds were also present. When the concen-
tration of CO was increased further, e.g. by bubbling
CO through the solution, no fluorenones were observed.
The reaction of 2 under these conditions showed, in
addition to 3, signals in the 31P{1H} and 19F NMR
spectra at δ 58.9 and at δ -132.2 (triplet, J FH ) 9 Hz),
respectively, suggesting the formation of a symmetrical
complex. This species was highly air-sensitive and
could not be isolated. In the presence of traces of air, a
stable yellow solid precipitated, which was identified as
σ-bond character, and these molecules readily undergo
insertion of small molecules into the nickel-aryne
bond.11-13 For example, Ni(η2-C6H4)(dcpe) (1) [dcpe )
1,2-bis(dicyclohexylphosphino)ethane, (C6H11)2PCH2-
CH2P(C6H11)2] reacts with CO2 or C2H4 to give the five-
membered ring metallacycles Ni(C6H4COO-2)(dcpe) or
Ni(C6H4CH2CH2-2)(dcpe), respectively.11 Insertions of
1 with alkynes proceed via similar metallacycles, but
these react readily with a second molecule of the alkyne
to form, after reductive elimination, a substituted
naphthalene.12
the phthalato complex Ni(OCOC6H2X2COO)(dcpe) (X )
F) (7) (Scheme 3). The analogue 6 (X ) H) was obtained
similarly from 1. Complexes 6 and 7 show a singlet in
their 31P{1H} NMR spectra at δ 77.8 and 78.7, respec-
tively, and 7 has a triplet at δ -137.8 (J FH ) 9 Hz) in
its 19F NMR spectrum. The 13C{1H} NMR spectra
contain a signal for the carboxylate carbon at δ 174.2
for 6 and δ 171.8 for 7, in agreement with the proposed
structures. The IR spectra display typical strong CdO
stretching bands at 1635 cm-1 (6) and 1637 cm-1 (7);
We therefore expected that 1 and its η2-4,5-difluo-
robenzyne analogue Ni((1,2-η)-4,5-F2C6H2)(dcpe) (2) would
react readily with CO, and we describe here the results
of this study.
Resu lts
cf. 1636 and 1622 cm-1 for Ni(C6H4COO-2)(dcpe).11 The
structure of 7 has been confirmed by X-ray analysis (see
below).
The reactions of 1 and 2 with CO are very dependent
on the concentration of CO. Gas uptake measurements
showed that 2.5 mol/mol of complex were absorbed when
CO was allowed to diffuse slowly into a dilute (0.05-
0.15 M) solution of 1 in toluene. As the 31P NMR signals
of 1 and 2 at δ 78.9 and 79.4, respectively, decreased in
intensity, a new species appeared having a singlet at δ
63.9 in the 31P NMR spectrum and strong bands at 1980
and 1920 cm-1 in the IR spectrum. This was identified
as Ni(CO)2(dcpe) (3), which was prepared for comparison
by treatment of Ni(η2-C2H4)(dcpe) with CO. Complex
3 was removed by decomposition with HCl, and the
organic products, extracted into hexane, were identified
as 9H-fluoren-9-one (4) and 2,3,6,7-tetrafluoro-9H-fluo-
ren-9-one (5), respectively (Scheme 2). The latter was
formed in ca. 90% yield as estimated from the 19F NMR
spectrum of the reaction mixture, which showed a pair
The symmetrical intermediate that forms 7 in the
presence of air is assumed to be the bis(acyl)nickel(II)
complex 9. The reaction of CO with 1 probably gener-
ates the corresponding intermediate 8, but this was not
observed directly. Similar bis(acyls) have been isolated
from the reaction of Ni(η2-alkyne)(bipy) with CO, and
their reaction with oxygen to give, after treatment with
H2SO4, a substituted maleic anhydride has been noted
(Scheme 1).8
At an early stage of this work, it was thought that
the isolated carboxylato complexes 6 and 7 were bis-
(acyls), and in an attempt to confirm this, they were
treated with iodine in dichloromethane or methanol in
the expectation of isolating phthalic acid or dimethyl
phthalate. The organic products formed were phthalic
anhydride (10) and 4,5-difluorophthalic anhydride (11),
respectively, presumably resulting from cleavage of the
Ni-O bonds of 6 and 7 by traces of HI and dehydration
(11) Bennett, M. A.; Hambley, T. W.; Roberts, N. K.; Robertson, G.
B. Organometallics 1985, 4, 1992.
(12) Bennett, M. A.; Wenger, E. Organometallics 1995, 14, 1267.
(13) Bennett, M. A.; Hockless, D. C. R.; Wenger, E. Organometallics
1995, 14, 2091.

930 Organometallics, Vol. 15, No. 3, 1996
Bennett et al.
Sch em e 4
reacts with another molecule of the benzyne complex
to form, after reductive elimination, the corresponding
fluorenone and Ni(CO)2(dcpe) (pathway A). This process
is represented by eq 3, which accounts for the observed
2Ni(C6H2X2)(dcpe) + 5CO f
2Ni(CO)2(dcpe) + C6H2X2COC6H2X2 (3)
X ) H, F
gas uptake under these conditions. A similar process
is thought to account for the formation of 9,10-bis-
(trifluoromethyl)-2,3,6,7-tetrafluorophenanthrene in the
reaction of hexafluoro-2-butyne with 2.12
In the presence of an excess of CO, e.g. when bubbled
through the solution or applied under pressure, a second
molecule of CO rapidly reacts with the monoacyl 14 to
form the corresponding bis(acyl) complex, which has
been detected in the case of 9 (pathway B). The bis-
(acyls) readily absorb oxygen to give the stable phthalato
complexes 6 and 7 and traces of the phthalic anhydride.
Aerial oxidation of monoacyls NiY(COR)L2 has been
reported to give paramagnetic monocarboxylato com-
plexes NiY(OCOR)Ln, which have not been structurally
characterized.4 The bis(acyl) intermediate can also
reductively eliminate benzocyclobutenedione, with for-
mation of Ni(CO)2(dcpe) (3); this reaction is probably
induced by an excess of CO. The elimination is revers-
ible; as the bis(acyl) is consumed by oxidation, it is re-
formed by addition of benzocyclobutenedione to 3. This
type of addition has precedent. Reaction of 3,4-diphe-
nylcyclobutenedione with Ni(bipy)(COD) at 100 °C in
toluene gives the corresponding bis(acyl).8 Cyclobutene-
diones or benzocyclobutenediones also add to Pt(PPh3)2
complexes to give bis(acyls), although these products are
unsymmetrical and result from the insertion of plati-
num into one C-CO bond.16-19 It is interesting that
the unsymmetrical bis(acyl) of this type formed from
benzocyclobutenedione and Pt(PPh3)4 is also oxidized
with oxygen to form a symmetrical dicarboxylato (ph-
thalato)platinum(II) complex similar to 6 and 7.16
However, since 9 shows only one resonance in both its
31P and 19F NMR spectra, an unsymmetrical structure
can be ruled out.
of the resulting phthalic acid.14 Small amounts of 11
were also formed during the reaction of intermediate 9
with air.
A second product detected together with 7 when CO
was either bubbled through or applied at 25 bar to
solutions of 2 showed a 19F NMR triplet in C6D6 at δ
-120.7 (J ) 6.4 Hz). This species and its analogue
obtained similarly from 1 show strong CdO stretching
bands in their IR spectra at 1805 and 1780 cm-1 and
are thought to be 4,5-difluorobenzocyclobutene-1,2-dione
(13) and benzocyclobutene-1,2-dione (12), respectively;
the values reported for the latter are 1808 and 1779
cm-1 15
However, these compounds could not be sepa-
.
rated from Ni(CO)2(dcpe), because they decomposed
both on addition of HCl and on attempted chromatog-
raphy on silica gel. The proposal is, however, supported
by the observation that cyclobutenedione is formed
reversibly by reductive elimination from the bis(acyl)
complex Ni(COCRdCRCO)(bipy) (R ) Me, Ph) on treat-
ment with CO (Scheme 1).8-10
During the reaction of the bis(acyl) intermediate 9
with oxygen to form the phthalato complex 7, the 19F
NMR signal assigned to 4,5-difluorobenzocyclobutene-
1,2-dione (13) also disappeared; hence, the formation of
13 also seems to be reversible.
Discu ssion
Scheme 4 provides a summary and rationalization of
the observations. Initially, one molecule of carbon
monoxide inserts into the nickel-benzyne bond to form
a highly reactive monoacyl (14) containing a four-
membered ring. A species of this type has been pro-
posed as the first product of carbonylation of Ni(CO)3(η2-
alkyne) in the Ni(CO)4-catalyzed hydrocarbonylation of
Bis(carboxylato) complexes cannot be formed by double
insertion of CO2 into nickel-aryne bonds of 1 or Ni-
(2,3-η-C10H6)(dcpe); only the monoinsertion products
Ni(C6H4COO-2)(dcpe) and Ni(2-C10H6COO-3)(dcpe) are
observed.11,13
Cr ysta l Str u ctu r e of Ni(OCO-4,5-F 2C6H2COO-2)-
alkynes,1,2,7 and a platinum analogue, Pt{C(O)C(Ph)dC-
(Ph)}(PPh3)2, has been isolated from the reaction of Pt-
(PPh3)4 or Pt(PPh3)2(trans-stilbene) with diphenylcyclo-
propenone.16,17 If the concentration of CO is low, 14
(d cp e) (7). The molecular geometry of Ni(OCO-4,5-
F2C6H2COO-2)(dcpe) (7) is shown in Figure 1. Atomic
coordinates, selected interatomic distances and angles,
and experimental details are given in Tables 1-3,
respectively.
The coordination geometry is close to square planar;
the nickel atom lies 0.042 Å from the least-squares plane
defined by the coordinated oxygen atoms (O1 and O3)
(14) A reviewer has suggested that these products are formed by
reductive elimination after one-electron oxidation of nickel; cf. the
formation of 4,4-dimethyl-3,4-dihydrocoumarin by iodination of the
oxanickelacycle Ni(CH2CMe2C6H4O)(phen) (Koo, K.; Hillhouse, G. L.;
Rheingold, A. L. Organometallics 1995, 14, 456). This seems to us
unlikely, because reductive elimination after iodine oxidation of 6 and
7 would initially form energy-rich compounds such as the peroxides
C6H2X2COO-OCOC6H2X2 or C6H2X2COOI.
(17) Burgess, J .; Kemmitt, R. D. W.; Morton, N.; Mortimer, C. T.;
Wilkinson, M. P. J . Organomet. Chem. 1980, 191, 477.
(18) Hamner, E. R.; Kemmitt, R. D. W.; Smith, M. A. R. J . Chem.
Soc., Chem. Commun. 1974, 841.
(15) Cava, M. P.; Napier, D. R.; Pohl, R. J . J . Am. Chem. Soc. 1963,
85, 2076.
(16) Evans, J . A.; Everitt, G. F.; Kemmitt, R. D. W.; Russell, D. R.
J . Chem. Soc., Chem. Commun. 1973, 158.
(19) Burgess, J .; Haines, R. I.; Hamner, R.; Kemmitt, R. D. W.;
Smith, M. A. R. J . Chem. Soc., Dalton Trans. 1975, 2579.

A (Phthalato)nickel(II) Complex
Organometallics, Vol. 15, No. 3, 1996 931
CH2Cl2 and added to a matrix of tetraglyme or 3-nitrobenzyl
alcohol. Mass spectra of the organic compounds were obtained
by the electron impact (EI) method on a VG ZAB2-SEQ or a
VG Micromass 7070F spectrometer. Microanalyses were done
in-house.
Sta r tin g Ma ter ia ls. The benzyne complexes Ni(η2-C6H4)-
(dcpe) (1) and Ni((1,2-η)-4,5-F2C6H2)(dcpe) (2) were obtained
by reduction of the corresponding (2-bromoaryl)nickel(II)
bromides with lithium in ether.11,12
P r ep a r a t ion of Ni(CO)2(d cp e) (3). Ni(η2-C2H4)(dcpe)11
(80 mg, 0.16 mmol) in THF (10 mL) was exposed to an
atmosphere of carbon monoxide. After the solution was stirred
for 4 h at room temperature, the 31P{1H} NMR spectrum
indicated that the reaction was complete. The solvent was
removed by evaporation, and the residue was extracted with
hexane. Evaporation of hexane gave 3 as a colorless solid (83
mg, 99%). 13C{1H} NMR (75.4 MHz, CD2Cl2): δ 23.0 (t, J CP
)
20), 26.7 (s), 27.5 (s), 28.5 (s), 29.3 (s, CH2), 35.6 (t, J CP ) 8,
CH), 204.9 (t, J CP ) 4, CO). 31P{1H} NMR (80.96 MHz, CD2-
Cl2): δ 63.9. IR (KBr): 2930 (s), 2860 (s), 1980 (s, ν(CO)), 1915
(s, ν(CO)), 1450 (m), 960 (m) cm-1
. FAB-MS (3-nitrobenzyl
alcohol, C28H48NiO2P2): m/e 508 (7, M - CO), 480 (47, M -
2CO), 371 (65), 355 (73), 289 (100).
F igu r e 1. ORTEP diagram for Ni(OCO-4,5-F2C6H2COO-
2)(dcpe) (7) with atom labeling and with 50% probability
ellipsoids.
In ser tion Rea ction s w ith Ca r bon Mon oxid e. All the
reactions were very dependent on the concentration of CO
present in solution and especially on the speed of diffusion of
CO into the solution. This parameter is hard to control
reproducibly, and reactions for which the conditions seemed
identical gave the products in varying proportions. Factors
such as stirring speeds, diffusion of CO via a cannula or via a
balloon, and evacuating the flask at room temperature or at
-30 °C before adding CO appeared to be important. Some
representative examples of the reactions carried out are given
below.
Rea ction of 1 w ith Ca r bon Mon oxid e. Meth od a .
Carbon monoxide was allowed to slowly diffuse into a flask
containing a solution of 1 (0.6 g, 0.83 mmol) in toluene (50
mL) via a cannula. The uptake of carbon monoxide (52 mL,
2.5 mol/mol of 1) was measured at 293 K over a period of 60
min, after which time the 31P{1H} NMR spectrum indicated
that the reaction was complete. The solvent was removed by
evaporation. The 31P{1H} NMR signal at δ 63.9 indicated that
the major phosphorus-containing product in the residue was
Ni(CO)2(dcpe) (3). Several unsymmetrical phosphorus-con-
taining compounds were also present in minor quantities. THF
(5 mL) and concentrated hydrochloric acid (2 mL) were added,
and the solvent was removed by evaporation. The residues
from several experiments were combined. Extraction with
hexane and removal of hexane from the extract allowed the
isolation of an organic compound which was identified (1H
NMR, IR, and EI-MS) as 9H-fluoren-9-one (4).
and the phosphorus atoms. The seven-membered ring
has a boat-shaped conformation similar to that in Ni-
(CH2CMe2C6H4COO)(PMe3)2 (15).20,21 The planes de-
fined by Ni-O1-O3 and by C7-C1-C2-C8 form
angles of 52 and 46°, respectively, with the plane defined
by O3-C8-C7-O1. The average Ni-O distance of
1.904(4) Å is very similar to the distances of 1.900 and
1.877 Å found in the monocarboxylato complex Ni(3-
C10H6COO-2)(dcpe) (16)13 and in 15,20,21 respectively.
The Ni-P distances of 7, 2.155(2) and 2.149(2) Å, are
also similar to the Ni-P distance trans to the carboxy-
late group in 16 of 2.144(2) Å. These values are lower
than typical Ni-P distances trans to σ-bonded carbon
atoms of about 2.20 Å, which is consistent with the
expected low trans influence of the oxygen donors.
Exp er im en ta l Section
Gen er a l P r oced u r es. All experiments were performed
under an inert atmosphere with use of standard Schlenk
techniques, and all solvents were dried and degassed prior to
use. All reactions involving benzyne complexes were carried
out under argon. NMR spectra were recorded on a Varian XL-
200E (1H at 200 MHz, 13C at 50.3 MHz, 19F at 188.1 MHz,
and 31P at 80.96 MHz), a Varian Gemini-300 BB (1H at 300
MHz, 13C at 75.4 MHz, and 31P at 121.4 MHz), or a Varian
VXR-300 instrument (1H at 300 MHz and 13C at 75.4 MHz).
Meth od b. Carbon monoxide (1 bar) was added from a
balloon to a solution of 1 in toluene (90 mL), prepared in situ
from NiBr(2-BrC6H4)(dcpe) (2.3 g, 2.7 mmol). After 44 h the
31P{1H} NMR spectrum indicated that 1 had reacted com-
pletely, forming a yellow precipitate. The solution was de-
canted from the solid, which was dried in vacuo and identified
1
The chemical shifts (δ) for H and 13C are given in ppm relative
as the phthalato complex Ni(OCOC6H4COO-2)(dcpe) (6) (0.66
g, 38%), presumably formed by diffusion of air into the flask.
1H NMR (200 MHz, CD2Cl2): δ 1.20-2.00 (m, 40H, CH2 of
C6H11), 2.20-2.40 (m, 8H, CH2 and CH of C6H11), 7.41 (AA′BB′
m, 2H, Harom), 7.60 (AA′BB′ m, 2H, Harom). 13C{1H} NMR (75.4
to residual signals of the solvent and to external 85% H3PO4
1
for 31P. The spectra of all nuclei (except 1H and 19F) were H
decoupled. The coupling constants (J ) are given in Hz.
Infrared spectra were measured in solution (KBr cells) or as
KBr disks on a Perkin-Elmer 683 or a Perkin-Elmer FTIR 1800
instrument. Mass spectra of the complexes were obtained on
a VG ZAB2-SEQ spectrometer by the fast-atom bombardment
(FAB) technique. Solutions of the samples were prepared in
MHz, CD2Cl2): δ 20.7 (t, J CP ) 30.2), 26.0 (s), 27.0 (t, J CP
)
7), 27.3 (t, J CP ) 9.8), 28.6 (s), 29.3 (s, CH2), 34.2 (t, J CP ) 17,
CH), 128.5 (s, CHarom), 128.8 (s, CHarom), 139.0 (s, C1,2), 174.2
(s, CO). 31P{1H} NMR (80.96 MHz, CD2Cl2): δ 77.8 (s). IR
(CH2Cl2): 2934 (s), 2854 (s), 1635 (s, ν(CdO)), 1448 (m), 1363
(s), 1273 (w). FAB-MS (tetraglyme, C34H52NiO4P2): m/e 645
(57, M + 1), 577 (100).
(20) Carmona, E.; Palma, P.; Paneque, M.; Poveda, M. L.; Gutie´rrez-
Puebla, E.; Monge, A. J . Am. Chem. Soc. 1986, 108, 6424.
(21) Carmona, E.; Gutie´rrez-Puebla, E.; Mar´ın, J . M.; Monge, A.;
Paneque, M.; Poveda, M. L.; Ruiz, C. J . Am. Chem. Soc. 1989, 111,
2883.
Rea ction of 2 w ith Ca r bon Mon oxid e. Meth od a .
slight vacuum was applied at room temperature to a flask
A

932 Organometallics, Vol. 15, No. 3, 1996
Ta ble 1. Atom ic Coor d in a tes for Ni(OCO-4,5-F 2C6H2COO-2)(d cp e) (7)
Bennett et al.
atom
x
y
z
atom
x
y
z
Ni1
Cl1
P1
P2
F1
0.19889(4)
0.2465(2)
0.29126(7)
0.16207(7)
0.0543(2)
0.1705(2)
0.2339(2)
0.2567(2)
0.1179(2)
0.0453(2)
0.1771(3)
0.1162(3)
0.0740(3)
0.0934(4)
0.1531(4)
0.1946(3)
0.2258(3)
0.0911(3)
0.2881(3)
0.2268(3)
0.1100(3)
0.1416(3)
0.0968(3)
0.0784(3)
0.0458(3)
0.03590(6)
0.2281(3)
0.09149(10)
0.1557(1)
0.0467(3)
0.0002(3)
-0.0687(3)
-0.1568(3)
-0.0129(3)
-0.0984(3)
-0.0595(4)
-0.0380(4)
-0.0040(4)
0.0099(5)
-0.0120(5)
-0.0487(4)
-0.0987(4)
-0.0525(4)
0.1844(4)
0.04518(4)
0.7870(1)
C16
C17
C18
C19
C20
C21
C22
C23
C24
C25
C26
C27
C28
C29
C30
C31
C32
C33
C34
C35
C36
C37
C38
C39
C40
0.0887(3)
0.1196(3)
0.0528(3)
0.0208(3)
0.0574(4)
0.1237(4)
0.1571(3)
0.3188(3)
0.3479(3)
0.3635(3)
0.4059(3)
0.3775(3)
0.3620(3)
0.3501(3)
0.4155(3)
0.4612(3)
0.4378(3)
0.3730(3)
0.3259(3)
0.3102(5)
0.3107(6)
0.3602(8)
0.4089(7)
0.4074(9)
0.3575(9)
0.2851(4)
0.1625(4)
0.1280(4)
0.1393(6)
0.0984(6)
0.1318(6)
0.1240(5)
0.1238(4)
0.0519(4)
0.0792(5)
0.1546(5)
0.2257(5)
0.2010(4)
0.0216(4)
0.0607(4)
-0.0021(4)
-0.0382(4)
-0.0770(4)
-0.0148(4)
0.2142(8)
0.1476(6)
0.1369(7)
0.194(1)
0.0211(3)
0.1381(3)
0.1364(3)
0.1954(3)
0.2436(3)
0.2466(3)
0.1874(3)
-0.0287(3)
-0.0624(3)
-0.1254(3)
-0.1263(3)
-0.0919(3)
-0.0293(3)
0.0774(2)
0.0860(3)
0.1109(3)
0.1680(3)
0.1597(3)
0.1351(3)
0.7398(4)
0.7077(5)
0.6713(5)
0.6692(6)
0.7038(7)
0.7406(5)
0.04509(7)
0.06791(7)
-0.1844(2)
-0.2199(2)
0.0237(2)
-0.0469(2)
0.0540(2)
0.0191(2)
-0.0667(3)
-0.0492(3)
-0.0892(3)
-0.1452(3)
-0.1630(3)
-0.1252(3)
-0.0273(3)
0.0124(3)
0.0901(2)
0.0753(3)
0.0102(3)
-0.0497(3)
-0.0983(3)
-0.0861(3)
-0.0271(3)
F2
O1
O2
O3
O4
C1
C2
C3
C4
C5
C6
C7
C8
C9
C10
C11
C12
C13
C14
C15
0.2311(4)
0.1954(4)
0.1867(4)
0.2172(4)
0.3059(5)
0.3153(5)
0.259(1)
0.2710(7)
Ta ble 2. Selected Bon d Dista n ces (Å) a n d Bon d
Ta ble 3. Cr ysta l a n d Str u ctu r e Refin em en t Da ta
An gles (d eg) for Ni(OCO-4,5-F 2C6H2COO-2)(d cp e)
(7)
for Ni(OCO-4,5-F 2C6H2COO-2)(d cp e) (7)
(a) Crystal Data
chem formula
fw
cryst syst
unit cell dimens
a (Å)
C34H50F2NiO4P2‚C6H5Cl
Bond Distances
794.98
Ni-P1
Ni1-O1
F1-C4
O1-C7
O3-C8
C1-C2
C1-C7
C2-C8
C4-C5
2.155(2)
1.907(4)
1.359(7)
1.274(7)
1.278(7)
1.396(8)
1.510(8)
1.524(8)
1.378(9)
Ni-P2
Ni-O3
F2-C5
O2-C7
O4-C8
C1-C6
C2-C3
C3-C4
C5-C6
2.149(2)
1.901(4)
1.368(7)
1.229(7)
1.232(7)
1.398(8)
1.393(8)
1.361(9)
1.368(9)
orthorhombic
21.214(4)
16.131(5)
22.869(3)
7825(2)
Pbca (No. 61)
1.349
b (Å)
c (Å)
V (Å3)
space group
Dc (g cm-3)
Z
8
Bond Angles
F(000)
3368
P1-Ni-P2
P1-Ni-O3
P2-Ni-O3
Ni-O1-C7
O1-C7-O2
O2-C7-C1
O3-C8-C2
87.50(7)
174.0(1)
91.0(1)
121.3(4)
123.6(6)
117.8(6)
117.1(6)
P1-Ni-O1
P2-Ni-O1
O1-Ni-O3
Ni-O3-C8
O1-C7-C1
O3-C8-O4
O4-C8-C2
90.8(1)
178.1(1)
90.7(2)
122.0(4)
118.6(5)
123.9(6)
118.9(6)
color, habit
cryst dimens
µ (cm-1)
yellow, prism
0.10 × 0.14 × 0.12
25.16 (Cu KR)
(b) Data Collection and Processing
diffractometer
X-radiation
Rigaku AFC6R
Cu KR (graphite
monochromated)
ω-2θ
1.00 + 0.30 tan θ
120.1
scan mode
containing a solution of the benzyne complex 2, prepared from
NiBr(2-Br-4,5-F2C6H2)(dcpe) (1.0 g, 1.3 mmol), in toluene (60
mL), which was then exposed to carbon monoxide (1 bar). After
being stirred 16 h at room temperature, 2 had reacted
completely and the 31P{1H} NMR spectrum indicated that the
major phosphorus-containing product was Ni(CO)2(dcpe). The
solvent was removed by evaporation, and the products were
extracted into hexane. The 19F NMR spectrum of the solution
showed two multiplets at δ -126.7 and δ -135.9, correspond-
ing to 2,3,6,7-tetrafluoro-9H-fluoren-9-one (5), and two mul-
tiplets at δ -142.0 and δ -148.0 corresponding to 3,3′,4,4′-
tetrafluorobiphenyl, formed by decomposition of 2. The mixture
was dissolved in THF (5 mL) and stirred with concentrated
HCl (2 mL). Extraction with hexane gave 20 mg of 5 (12%
based on nickel(II) precursor). 1H NMR (200 MHz, CD2Cl2):
ω-scan width
2θ limits (deg)
data collcd (h,k,l)
no. of reflns
tot
(-18,0,0) to (0,24,26)
6431
3271 [I > 3σ(I)]
azimuthal scans (0.884-1.000)
obsd
abs corr (transm factors)
(c) Structure Analysis and Refinementa
structure soln
Patterson methods
(PATTY,23 DIRDIF9223
full-matrix least squares
452
)
refinement
no. of params
weighting scheme
R(obsd data) (%)
Rw (obsd data) (%)
w ) 4Fo2/[σ2(Fo2) + (0.007Fo2)2]
5.0
4.7
a
All calculations were performed by use of teXsan24 with
neutral atom scattering factors from Cromer and Waber,25 ∆f and
∆f ′ values from ref 26, and mass attenuation coefficients from ref
27. Anomalous dispersion effects were included in Fc.28
δ 6.20 (dd, 1H, J FH ) 10, J FH ) 7, H3,6), 6.90 (dd, 1H, J FH
)
10, J FH ) 7, H2,7). 13C{1H} NMR (75.4 MHz, CD2Cl2): δ 110.8
(d, J CF ) 20, CH), 114.4 (d, J CF ) 20, CH), 128.8 (d, J CF ) 12,
C), 132.3 (d, J CF ) 9, C), 198.2 (s, CO); signals of CF were not
located. 19F NMR (188.1 MHz, CD2Cl2): δ -126.7 (5-line m,
J FH ) 9), -135.9 (5-line m, J FH ) 9). IR (CH2Cl2): 2850 (m),
1720 (m, ν(CdO)), 1500 (m) cm-1. EI-MS (C13H4F4O): m/e 252
(100, M), 224 (30, M - CO).
Meth od b. A vacuum was applied to a flask containing a
solution of 2 in toluene (35 mL) that had been prepared from
NiBr(2-Br-4,5-F2C6H2)(dcpe) (1.0 g, 1.3 mmol), and the solution
was then cooled to -30°C. Carbon monoxide (1 atm) was
introduced, and the solution was allowed to warm to room

A (Phthalato)nickel(II) Complex
Organometallics, Vol. 15, No. 3, 1996 933
temperature and was stirred for 16 h, forming a precipitate.
The 19F NMR spectrum in C6D6 of the supernatant solution
contained signals corresponding to 5 and a signal at δ -123.3
due to 4,5-difluorophthalic anhydride (11), whereas the 31P
NMR spectrum showed the presence of 3. The solid was
washed with hexane and was identified as the phthalato
1782 cm-1 due to 13, in addition to the ν(CO) bands of 3. On
exposure to air, the peaks due to 9 and 13 disappeared and
only 11 remained, together with the yellow precipitate 7.
Rea ction of P h th a la to Com p lexes 6 a n d 7 w ith Iod in e.
A solution of 7 (0.03 g, 0.05 mmol) in CD2Cl2 (0.5 mL) was
treated with iodine (0.025 g, 0.1 mmol) at room temperature.
The 19F NMR spectrum (CD2Cl2) contained a signal at δ
-121.2, while the 31P{1H} NMR spectrum contained only a
broad peak at δ 82.0, corresponding to NiI2(dcpe). The mixture
was filtered through Celite, and 4,5-difluorophthalic anhydride
(11) was isolated. 19F NMR (188.1 MHz): CD2Cl2), δ -121.2
(t, J ) 6.2); C6D6 δ -123.3 (t, J ) 7.5); literature value in
acetone-d6, δ -123.7.22 EI-MS (C8H2F2O3): m/e 183 (17, M -
1), 57 (100).
complex Ni(OCO-4,5-F2C6H2COO-2)(dcpe) (7), presumably
formed from air in the reaction flask. Crystals suitable for
X-ray analysis were grown from chlorobenzene. 1H NMR (200
MHz, CD2Cl2): δ 1.10-2.00 (m, 40H, CH2 of C6H11), 2.10-2.20
(m, 4H, CH2), 2.30-2.40 (m, 4H, CH of C6H11), 7.42 (t, 2H,
J FH ) 9, Harom). 13C{1H} NMR (75.4 MHz, CD2Cl2): δ 20.6 (t,
J CP ) 20), 26.0 (t), 26.9-27.3 (m), 28.7 (s), 30.5 (s, CH2), 34.3
(t, J CP ) 11, CH), 117.8 (t,J HF ) 9, C3,6-H), 136.4 (s, C1,2), 150.3
(dd, J CF ) 249, J CF ) 14, C4,5-F), 171.8 (s, CO). 19F NMR (188.1
MHz, CD2Cl2): δ -137.8 (t, J FH ) 9). 31P{1H} NMR (80.96
MHz, CD2Cl2): δ 78.7 (s). IR (CH2Cl2): 2935 (s), 2856 (s), 1637
(s, ν(CdO)), 1504 (m) 1448 (m), 1368 (s), 1277 (w). FAB-MS
(tetraglyme, C34H50F2NiO4P2): m/e 681 (60, M + 1), 455 (100).
Anal. Calcd for C34H50F2NiO4P2: C, 59.9; H, 7.4. Found: C,
59.3; H, 7.7.
A similar reaction with 1 gave phthalic anhydride (10).
X-r a y cr ysta llogr a p h y of Ni(OCO-4,5-F 2C6H2COO-2)-
(d cp e) (7). Crystal data and details of data collection, data
processing, structure analysis, and structure refinement are
in Table 3. The structure of 7 was solved by Patterson
methods (PATTY)23 and was expanded using Fourier tech-
niques (DIRDIF92).23 All non-hydrogen atoms were refined
anisotropically by full-matrix least squares. Hydrogen atoms
were included at calculated positions (C-H 0.95 Å) and held
fixed. All calculations were performed using the teXsan
Structure Analysis Software of Molecular Structure Corp.
Meth od c. Under vigorous stirring, 150 mL of a toluene
solution of 2, prepared from NiBr(2-Br-4,5-F2C6H2)(dcpe) (3.0
g, 4 mmol), was treated with carbon monoxide introduced from
a balloon. After the mixture was stirred overnight, the 19F
NMR spectrum (C6D6) contained peaks at δ -126.7 and δ
-135.9 due to 2,3,6,7-tetrafluoro-9H-fluoren-9-one (5), a very
small peak at δ -123.3 due to 4,5-difluorophthalic anhydride
(11) [lit. δ -123.7 in acetone-d6],22 a triplet at δ -120.7 (J )
6.4) which was attributed to 4,5-difluorobenzocyclobutenedione
(13), and a peak at δ -137.8 due to the phthalato complex 7.
Another intense triplet at δ -132.2 (J ) 9), corresponding to
Ack n ow led gm en t. M.G.H. thanks the ARC for an
Australian Research Fellowship, and M.S. gratefully
acknowledges the receipt of an RSC Honours Year
Scholarship and a National Undergraduate Scholarship.
Su p p or tin g In for m a tion Ava ila ble: For structure 7, a
packing diagram, text describing X-ray procedures, and tables
of atomic coordinates with isotropic displacement parameters,
bond lengths, bond angles, torsion angles, anisotropic displace-
ment parameters, and data collection parameters (27 pages).
Ordering information is given on any current masthead page.
a
31P NMR signal at δ 58.9 was assumed to be due to the bis-
(acyl) complex Ni(OC-4,5-F2C6H2CO-o)(dcpe) (9). The propor-
tions of the products changed on further stirring, the peak at
δ -132.2 decreasing and that at δ -123.3 increasing in
intensity. After 2 days the only components of the product
mixture observed in the 19F NMR spectrum were 11 and 5,
and 7 had precipitated. The mixture was decanted, and 7 was
recovered in 25% yield.
OM950699V
(23) Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bosman, W. P.;
Garcia-Granda, S.; Gould, R. O.; Smits, J . M. M.; Smykalla, C. The
PATTY and DIRDIF Program System, Technical Report of the Crystal-
lographic Laboratory; University of Nijmegen: Nijmegen, The Neth-
erlands, 1992.
(24) teXsan: Single Crystal Structure Analysis Software, Version
1.6c; Molecular Structure Corp.: The Woodlands, TX 77381, 1993.
(25) Cromer, D. T.; Waber, J . T. International Tables for X-Ray
Crystallography; Kynoch Press: Birmingham, England, 1974; Vol. IV.
(26) Creagh, D. C.; McAuley, W. J . International Tables for X-ray
Crystallography; Kluwer Academic: Boston, MA, 1992; Vol. C, p 219.
(27) Creagh, D. C.; Hubbell, J . H. International Tables of X-ray
Crystallography; Kluwer Academic: Boston, MA, 1992; Vol. C, p 200.
(28) Ibers, J . A.; Hamilton, W. C. Acta Crystallogr. 1964, 17, 781.
Meth od d . A carbon monoxide pressure of 25 bar was
applied to a solution of 2 in toluene (150 mL) that had been
prepared as in method c. After 5 days, the 19F NMR spectrum
of the reaction mixture showed peaks corresponding to the bis-
(acyl) intermediate 9 and 4,5-difluorobenzocyclobutenedione
(13). The IR spectrum contained ν(CO) bands at 1803 and
(22) Fifolt, M. J .; Sojka, S. A.; Wolfe, R. A.; Hojnicki, D. S.; Bieron,
J . F.; Dinan, F. J . J . Org. Chem. 1989, 54, 3019.