Formation of (diphenylphosphino)naphthalenes by double insertion of (alkynyl)diphenylphosphines into nickel(0)-benzyne complexes

Article abstract of DOI:10.1021/om990749m

(Alkynyl)diphenylphosphines Ph₂PC≡CR (R = H, Me, Ph, PPh₂) undergo double insertion into the nickel(0)-benzyne bond of the complexes [Ni{(1,2-η)-4,5-X₂C₆H₂}(PEt ₃)₂] (X = H (1a), F (1b)) to give mixtures of nickel(O) complexes containing (diphenylphosphino)-naphthalenes, which in some cases are formed with high regioselectivity. Bromination of the mixtures of nickel(O) complexes obtained from Ph₂PC≡CR (R = Me, Ph) and la or lb gives in high yield the chelate NiBr₂ complexes [NiBr₂{6,7-X₂C₁₀H₂-1,4-Y ₂-2,3-(PPh₂)₂}] (X = H, Y = Me (6a), Ph (11a); X = F, Y = Me (6b), Ph (11b)), from which the corresponding 1,4-disubstituted 2,3-naphthylenebis(diphenylphosphines) 12a, 13a, 12b, and 13b can be liberated by treatment with NaCN in DMSO at 60 °C or dimethylglyoxime/ammonia at room temperature. Derivatives in which only one of the phosphorus atoms is oxidized, 6,7-X₂C₁₀H₂-1,4-Me₂-2-PPh ₂-3-P(O)PPh₂ (X = H (15a), F (15b)), have also been prepared. The regioselectivity of the reactions of Ph₂PC≡CH with 1b is poorer than that of Ph₂PC≡CR (R = Me, Ph), and products with a 1,3-substitution pattern predominate. Reaction of Ph₂PC≡CPPh₂ (dppa) with la gives, after addition of bromine, a pair of isomers in which NiBr₂ is attached to the phosphorus atoms at the 2,3- and 1,2-positions, respectively, of the tetrakis(tertiary phosphine) species C₁₀H₄-l,2,3,4-(PPh₂)₄ (19). The molecular structures of complexes lib and [NiBr₂{C₁₀H₄-1,2)3-(PPh₂) ₃-4-{P(O)Ph₂}-κ-P¹,P²}] (18), and of a disordered 73:27 mixture of the bis(diphenylphosphine oxides) C₁₀H₄-1,4-(PPh₂)₂-2,3-{P(O)Ph ₂}₂ (20) and C₁₀H₄-1,2-(PPh₂)₂-3,4-{P(O)Ph ₂}₂ (21) obtained by partial oxidation of 19, have been determined by single-crystal X-ray diffraction. The regioselectivities of the insertions of Ph₂PC≡CMe and Ph₂PC≡CH into 1a and 1b are similar to those of MeC≡CCO₂Me and HC≡CCO₂Me, respectively, and factors that influence them are discussed.

Full text of DOI:10.1021/om990749m

1522
Organometallics 2000, 19, 1522-1533
F or m a tion of (Dip h en ylp h osp h in o)n a p h th a len es by
Dou ble In ser tion of (Alk yn yl)d ip h en ylp h osp h in es in to
Nick el(0)-Ben zyn e Com p lexes
Martin A. Bennett,* Christopher J . Cobley, A. David Rae, Eric Wenger, and
Anthony C. Willis
Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
Received September 23, 1999
(Alkynyl)diphenylphosphines Ph2PCtCR (R ) H, Me, Ph, PPh2) undergo double insertion
into the nickel(0)-benzyne bond of the complexes [Ni{(1,2-η)-4,5-X2C6H2}(PEt3)2] (X ) H
(1a ), F (1b)) to give mixtures of nickel(0) complexes containing (diphenylphosphino)-
naphthalenes, which in some cases are formed with high regioselectivity. Bromination of
the mixtures of nickel(0) complexes obtained from Ph2PCtCR (R ) Me, Ph) and 1a or 1b
gives in high yield the chelate NiBr2 complexes [NiBr2{6,7-X2C10H2-1,4-Y2-2,3-(PPh2)2}] (X
) H, Y ) Me (6a ), Ph (11a ); X ) F, Y ) Me (6b), Ph (11b)), from which the corresponding
1,4-disubstituted 2,3-naphthylenebis(diphenylphosphines) 12a , 13a , 12b, and 13b can be
liberated by treatment with NaCN in DMSO at 60 °C or dimethylglyoxime/ammonia at room
temperature. Derivatives in which only one of the phosphorus atoms is oxidized, 6,7-X2C10H2-
1,4-Me2-2-PPh2-3-P(O)PPh2 (X ) H (15a ), F (15b)), have also been prepared. The regiose-
lectivity of the reactions of Ph2PCtCH with 1b is poorer than that of Ph2PCtCR (R ) Me,
Ph), and products with a 1,3-substitution pattern predominate. Reaction of Ph2PCtCPPh2
(dppa) with 1a gives, after addition of bromine, a pair of isomers in which NiBr2 is attached
to the phosphorus atoms at the 2,3- and 1,2-positions, respectively, of the tetrakis(tertiary
phosphine) species C10H4-1,2,3,4-(PPh2)4 (19). The molecular structures of complexes 11b
and [NiBr2{C10H4-1,2,3-(PPh2)3-4-{P(O)Ph2}-κP1,P2}] (18), and of a disordered 73:27 mixture
of the bis(diphenylphosphine oxides) C10H4-1,4-(PPh2)2-2,3-{P(O)Ph2}2 (20) and C10H4-1,2-
(PPh2)2-3,4-{P(O)Ph2}2 (21) obtained by partial oxidation of 19, have been determined by
single-crystal X-ray diffraction. The regioselectivities of the insertions of Ph2PCtCMe and
Ph2PCtCH into 1a and 1b are similar to those of MeCtCCO2Me and HCtCCO2Me,
respectively, and factors that influence them are discussed.
In tr od u ction
robenzyne, 2,3-naphthalyne; L2 ) 2PEt3, dcpe11) un-
dergo double insertions with alkynes.9,12-14 After re-
ductive elimination of the NiL2 fragment from the
presumed intermediate nickelacycle, the products are
substituted naphthalenes (from the benzyne or 4,5-
difluorobenzyne complexes) or anthracenes (from the
2,3-naphthalyne complexes). These insertions are often
regiospecific. For example, the reaction of methyl 2-bu-
tynoate with [Ni{(1,2-η)-4,5-X2C6H2}(PEt3)2] (X ) H
(1a ), F (1b)) leads exclusively in each case to the
naphthalene having the carboxylate groups in the 2,3-
positions. In contrast, tert-butylacetylene shows the
opposite regioselectivity in its reactions with [Ni{(1,2-
η)-4,5-X2C6H2}(PEt3)2] (X ) H (1a ), F (1b)), which give
exclusively the corresponding 1,3-di-tert-butylnaphtha-
Despite their short lifetimes under normal conditions,
arynes are versatile reagents that have been widely
used in organic synthesis because of their ability to
undergo Diels-Alder reactions, cycloadditions with 1,3-
dipoles, and additions to nucleophiles.1-5 Additional
possibilities for organic synthesis are offered by coor-
dination to a transition-metal-containing fragment,
which both stabilizes and alters the reactivity of an
aryne.6-10 We have shown that nickel(0) complexes of
the type [Ni(η2-aryne)L2] (aryne ) benzyne, 4,5-difluo-
* To whom correspondence should be addressed. Fax: +61 2 6249
3216. E-mail: bennett@rsc.anu.edu.au.
(1) Hoffmann, R. W. Dehydrobenzene and Cycloalkynes; Academic
Press: New York, 1967.
(2) Gilchrist, T. L. In The Chemistry of Triple-Bonded Functional
Groups; Patai, S., Rappoport, Z., Eds.; Wiley: New York, 1983; Vol.
Suppl. C2, p 383.
(3) Hart, H. In The Chemistry of Triple-Bonded Functional Groups;
Patai, S., Ed.; Wiley: Chichester, U.K., 1994; Vol. Suppl. C2.
(4) Kessar, S. V. In Comprehensive Organic Synthesis; Trost, B. M.,
Fleming, I., Semmelhack, M. F., Eds.; Pergamon: Oxford, U.K., 1991;
Vol. 4, p 483.
(5) Oppolzer, W. In Comprehensive Organic Synthesis; Trost, B. M.,
Fleming, I., Paquette, L. A., Eds.; Pergamon: Oxford, U.K., 1991; Vol.
5, p 379.
(6) Buchwald, S. L.; Nielsen, R. B. Chem. Rev. 1988, 88, 1047.
(7) Bennett, M. A.; Schwemlein, H. P. Angew. Chem., Int. Ed. Engl.
1989, 28, 1296.
(8) Buchwald, S. L.; Broene, R. D. In Comprehensive Organometallic
Chemistry II; Abel, E. W., Stone, F. G. A., Wilkinson, G., Hegedus, L.
S., Eds.; Pergamon: Oxford, U.K., 1995; Vol. 12, p 771.
(9) Bennett, M. A.; Wenger, E. Chem. Ber./ Recl. 1997, 130, 1029.
(10) J ones, W. M.; Klosin, J . Adv. Organomet. Chem. 1998, 42, 147.
(11) Abbreviations: dcpe ) 1,2-bis(dicyclohexylphosphino)ethane,
Cy2PCH2CH2PCy2; dppa ) bis(diphenylphosphino)acetylene, Ph2Pt
CPPh2.
(12) Bennett, M. A.; Wenger, E. Organometallics 1995, 14, 1267.
(13) Bennett, M. A.; Hockless, D. C. R.; Wenger, E. Organometallics
1995, 14, 2091.
(14) Bennett, M. A.; Wenger, E. Organometallics 1996, 15, 5536.
10.1021/om990749m CCC: $19.00 © 2000 American Chemical Society
Publication on Web 03/21/2000

Insertion of Phosphines into Ni(0) Benzyne Complexes
Organometallics, Vol. 19, No. 8, 2000 1523
Sch em e 1
lenes. These differences have been attributed to a
combination of electronic and steric effects.9,12
We were interested to know whether (alkynyl)diphen-
ylphosphines such as Ph2PCtCR and Ph2PCtCPPh2
(dppa) would undergo double insertions with complexes
1a and 1b to give novel tertiary phosphines based on
the naphthalene ring and, if so, with what regioselec-
tivity. As potentially bifunctional ligands, acetylenes of
this type have been used extensively in organometallic
and coordination chemistry, especially for the formation
of polynuclear metal complexes.15 Apart from the results
reported in our preliminary communication,16 however,
there are only two examples of the insertion of an
(alkynyl)phosphine into a metal-carbon σ-bond, viz. the
reactions of Ph2PCtCR (R ) H, Ph) and t-BuP(CtCPh)2
with zirconocene-benzyne, [Cp2Zr(η2-C6H4)], a species
that is generated in situ by heating [Cp2Zr(η1-C6H5)2].17,18
Of particular relevance to the work described here are
the reactions of Ph2PCtCR (R ) H, Ph), which give
stereoselectively (2-diphenylphosphino)zirconaindene de-
rivatives (eq 1).17
In two of the species, the 31P signals in both regions
appear as triplets, with P-P couplings of ca. 25 Hz,
consistent with the presence of two auxiliary P donors,
i.e., PEt3 and Ph2PCtCMe. In the third species, how-
ever, the two ancillary ligands are clearly different: the
signal assigned to C10H4-1,4-Me2-2,3-(PPh2)2 appears as
a doublet of doublets, whereas the remaining signals
are doublets of triplets at δ 5.4 and 9.7 and are assigned
to coordinated Ph2PCtCMe and PEt3, respectively.
Thus, the mixtures obtained by reaction of 1a and 1b
with Ph2PCtCMe are believed to be four-coordinate
nickel(0) complexes of general formula [Ni{6,7-X2C10H2-
1,4-Me2-2,3-(PPh2)2}(L1)(L2)] (X ) H, F), where L1 ) L2
) PEt3 (2a ,b), L1 ) L2 ) Ph2PCtCMe (3a ,b), or L1 )
PEt3 and L2 ) Ph2PCtCMe (4a ,b) (Scheme 1), all of
which arise from regiospecific double insertion of the
alkynylphosphine. The formulation of these very reac-
tive and labile Ni(0) species is supported by their
reaction with dcpe. Addition of the chelating ligand to
the red solutions liberates the auxiliary ligands, thus
simplifying the 31P{1H} NMR spectra. The products are
the bis(chelate)nickel(0) complexes [Ni{6,7-X2C10H2-1,4-
Me2-2,3-(PPh2)2}(dcpe)] (X ) H (5a ), F (5b)), whose 31P
NMR spectra consist of a pair of triplets at δ ca. 47 and
Resu lts
(1) (1-P r op yn yl)d ip h en ylp h osp h in e, P h 2P Ct
CMe, a n d (P h en ylet h yn yl)d ip h en ylp h osp h in e,
P h 2P CtCP h . The benzyne-nickel(0) complexes [Ni-
{(1,2-η)-4,5-X2C6H2}(PEt3)2] (X ) H (1a ), F (1b)) react
readily with Ph2PCtCMe to give red solutions whose
31P{1H} NMR spectra are complex but consistent with
the presence of three nickel(0) complexes characterized
by groups of multiplets in the regions δ 50 and δ 5-10.
The strongly deshielded nature of the first group sug-
gests immediately that they arise from phosphorus
atoms in a five-membered chelate ring,19 as would be
expected for coordinated 1,4-dimethyl-2,3-naphthyl-
enebis(diphenylphosphine), C10H4-1,4-Me2-2,3-(PPh2)2.
(15) Selected references: (a) Patel, H. A.; Carty, A. J .; Hota, N. K.
J . Organomet. Chem. 1973, 50, 247. (b) Carty, A. J .; Paik, H. N.; Ng,
T. W. J . Organomet. Chem. 1974, 74, 279. (c) Carty, A. J .; J acobson,
S. E.; Simpson, R. J .; Taylor, N. J . J . Am. Chem. Soc. 1975, 97, 7254.
(d) Taylor, N. J .; Carty, A. J . J . Chem. Soc., Dalton Trans. 1976, 799.
(e) Carty, A. J . Pure Appl. Chem. 1982, 54, 113. (f) Sappa, E.; Predieri,
G.; Tiripicchio, A.; Camellini, M. T. J . Organomet. Chem. 1985, 297,
103. (g) Nucciarone, D.; MacLaughlin, S. A.; Taylor, N. J .; Carty, A. J .
Organometallics 1988, 7, 106. (h) Charkas, A. A.; Randall, L. H.;
MacLaughlin, S. A.; Mott, G. N.; Taylor, N. J .; Carty, A. J . Organo-
metallics 1988, 7, 969. (i) Sappa, E.; Pasquinelli, G.; Tiripicchio, A.;
Camellini, M. T. J . Chem. Soc., Dalton Trans. 1989, 601. (j) Braga,
D.; Benvenutti, M. H. A.; Grepioni, F.; Vargas, M. D. J . Chem. Soc.,
Chem. Commun. 1990, 1730. (k) Fornie´s, J .; Lalinde, E.; Mart´ın, A.;
Moreno, M. T.; Welch, A. J . J . Chem. Soc., Dalton Trans. 1995, 1333.
(l) Moldes, I.; Ros, J . Inorg. Chim. Acta 1995, 232, 75. (m) Louattani,
E.; Suades, J .; Alvarez-Larena, A.; Piniella, J . F.; Germain, G. J .
Organomet. Chem. 1996, 506, 121. (n) Dickson, R. S.; de Simone, T.;
Parker, R. J .; Fallon, G. D. Organometallics 1997, 16, 1531. (o) Ara,
I.; Falvello, L. R.; Ferna´ndez, S.; Fornie´s, J .; Lalinde, E.; Mart´ın, A.;
Moreno, M. T. Organometallics 1997, 16, 5923.
2
52 (2J PP ) 27 Hz). Similar values of J PP have been
reported for the complexes [Ni(dmpe)L2] (L ) PMe3,
PPh3)20 and for other unsymmetrical nickel(0) complexes
containing tertiary phosphines and coordinated ole-
fins.21-23 The structure of the poorly soluble complex 5a
1
has also been confirmed by H NMR spectroscopy and
mass spectrometry. Furthermore, reaction of [Ni(η2-
C2H4)(dcpe)] with the free phosphine C10H4-1,4-Me2-2,3-
(PPh2)2 (see below) regenerates complex 5a , as shown
by 31P NMR spectroscopy.
(20) Po¨rschke, K. R.; Mynott, R.; Kru¨ger, C.; Roma˜o, M. J . Z.
Naturforsch., B 1984, 39, 1076.
(21) Po¨rschke, K. R.; Mynott, R.; Angermund, K.; Kru¨ger, C. Z.
Naturforsch., B 1985, 40, 199.
(22) Bennett, M. A.; Chiraratvatana, C. J . Organomet. Chem. 1985,
296, 255.
(23) Yamamoto, T.; Ishizu, J .; Komiya, S.; Nakamura, Y.; Yamamoto,
A. J . Organomet. Chem. 1979, 171, 103.
(16) Bennett, M. A.; Cobley, C. J .; Wenger, E.; Willis, A. C. Chem.
Commun. 1998, 1307.
(17) Miquel, Y.; Igau, A.; Donnadieu, B.; Majoral, J .-P.; Dupuis, L.;
Pirio, N.; Meunier, P. Chem. Commun. 1997, 279.
(18) Dupuis, L.; Pirio, N.; Meunier, P.; Igau, A.; Donnadieu, B.;
Majoral, J .-P. Angew. Chem., Int. Ed. Engl. 1997, 36, 987.
(19) Garrou, P. E. Chem. Rev. 1981, 81, 229.

1524 Organometallics, Vol. 19, No. 8, 2000
Bennett et al.
Sch em e 2
at δ ca. -19, the P-P coupling constants being ca. 30
Hz. The multiplets at higher frequency must be as-
signed to inequivalent phosphorus atoms of the ap-
propriate naphthylenebis(diphenylphosphine), while the
chemical shift of the remaining signal is suggestive of
an uncoordinated phosphorus atom of Ph2PCtCPh.
These data are consistent with the formulation [Ni{6,7-
X2C10H2-1,4-Ph2-2,3-(PPh2)2}(η2-Ph2PCtCPh)] (X ) H
(9a ), F (9b)), the alkynylphosphine being bound only via
its triple bond to trigonal-planar-coordinated nickel(0).
This formulation is supported by the isolation of [Ni-
(dcpe)(η2-Ph2PCtCPh)] (10) as a thermally sensitive
yellow solid from the reaction of Ph2PCtCPh with [Ni-
(C2H4)(dcpe)] (eq 2). This complex contains a parent ion
Treatment of solutions containing 2a -4a or 2b-4b
with bromine gives the dibromonickel(II) complexes
[NiBr2{6,7-X2C10H2-1,4-Me2-2,3-(PPh2)2}] (X ) H (6a ),
F (6b)) as air-stable, orange solids in almost quantita-
tive yield based on nickel. They have been characterized
by elemental analysis, NMR (1H, 31P) spectroscopy, and,
in the case of 6b, by single-crystal X-ray diffraction.16
The coordination geometry about the metal atom is
square planar, and the coordinated PPh2 groups are
located on carbon atoms 2 and 3 of the naphthalene ring.
The 31P chemical shifts of 6a and 6b (δ 65-66) are
strongly deshielded, as expected for a rigid, five-
membered chelate ring; cf. δP 68.6 for [Ni{S2C2(CN)2}-
(cis-Ph2PCHdCHPPh2)].24 In contrast with the behavior
of [Ni(η2-C6H4)(PEt3)2] (1a ), the dcpe complex [Ni(η2-
C6H4)(dcpe)] shows no reaction with Ph2PCtCMe, even
after 1 week at room temperature.
The ligand (phenylethynyl)diphenylphosphine, Ph2-
PCtCPh, also undergoes double insertions with the
benzyne-nickel(0) complexes 1a and 1b at room tem-
perature to generate the corresponding coordinated 1,4-
diphenylnaphthylene-2,3-bis(diphenylphosphines) (Scheme
2). The products formed immediately on mixing Ph2PCt
CPh (2 mol) with 1a or 1b (1 mol) are the bis(tri-
ethylphosphine)nickel(0) complexes [Ni{6,7-X2C10H2-
1,4-Ph2-2,3-(PPh2)2}(PEt3)2] (X ) H (7a ), F (7b)), whose
31P{1H} NMR spectra show a pair of multiplets at δ ca.
7 and 52 due to PEt3 and the naphthylene ligand,
respectively. In a slower reaction, one of the coordinated
triethylphosphine ligands is replaced by Ph2PCtCPh
to give [Ni{6,7-X2C10H2-1,4-Ph2-2,3-(PPh2)2}(PEt3)(Ph2-
PCtCPh)] (X ) H (8a ), F (8b)), characterized by three
multiplets in the 31P{1H} NMR spectra at δ ca. 3, 7, and
52 due to coordinated Ph2PCtCPh, PEt3, and the
naphthylene ligand, respectively. In contrast with the
behavior of Ph2PCtCMe, however, there is no evidence
for the formation of the bis(alkynylphosphine) complex.
Instead, in each case, complexes 7a ,b and 8a ,b are
finally replaced by a third species characterized by the
presence in its 31P{1H} NMR spectrum of a pair of
multiplets in the region of δ 63 and a doublet of doublets
peak in its FAB mass spectrum and shows a 31P NMR
pattern analogous to that of 9, viz. two doublets of
doublets in the region of δ 70 due to inequivalent
phosphorus atoms of dcpe and a doublet of doublets at
δ -14.5 due to the uncoordinated phosphorus atom of
Ph2PCtCPh. In 10, the change in the 13C NMR chemi-
cal shift of the two quaternary carbons of the alkyne
shows clearly that these carbons are now coordinated
to the metal center; the signals appear as doublets at
δC 87 and 108 in the free alkyne and as doublets of
doublets of doublets at δC 141 and 150 in the complex.
The structure of the analogous complex [Ni(dcpe)(η2-
Ph2PCtCMe)] has been confirmed by single-crystal
X-ray diffraction.25
Addition of bromine to the solutions of nickel(0)
complexes 7a -9a or 7b-9b gives the corresponding
orange nickel(II) complexes [NiBr2{6,7-X2C10H2-1,4-Ph2-
2,3-(PPh2)2}] (X ) H (11a ), F (11b)), which show the
expected 31P NMR singlets in the region of δ 67. The
structure of complex 11b has been confirmed by single-
crystal X-ray diffraction (see below). Complex 11a has
been prepared, in 66% yield based on nickel, in a one-
pot procedure starting from the precursor to 1a , [NiBr-
(2-BrC6H4)(PEt3)2]; reduction to 1a , insertion of Ph2PCt
CPh, and bromination were carried out in successive
steps. The yield is somewhat lower than that of complex
6a obtained by use of Ph2PCtCMe, probably because
the formation of the side-bonded complex 9a scavenges
some of the alkynylphosphine required for double inser-
tion. The sterically bulky (alkynyl)diphenylphosphines
Ph2PCtCR (R ) t-Bu, SiMe3) do not react with com-
plexes 1a or 1b at room temperature.
Liberation of the ditertiary phosphines from their
dibromonickel(II) complexes by treatment with an ex-
cess of NaCN requires unexpectedly forcing conditions,
viz. overnight heating to 60 °C in DMSO. In this way
the 2,3-naphthylenebis(diphenylphosphines) 6,7-X2C10H2-
1,4-Y2-2,3-(PPh2)2 (X ) H, Y ) Me (12a ); X ) F, Y )
Me (12b); X ) F, Y ) Ph (13b)) have been obtained
almost quantitatively from complexes 6a ,b and 11b,
respectively. An alternative, milder procedure, which
(24) Bowmaker, G. A.; Williams, J . P. J . Chem. Soc., Dalton Trans.
1993, 3593.
(25) Bennett, M. A.; Castro, J .; Kopp, M. R.; Wenger, E.; Willis, A.
C. Unpublished work.

Insertion of Phosphines into Ni(0) Benzyne Complexes
Organometallics, Vol. 19, No. 8, 2000 1525
Sch em e 3
was tested with complex 11a , is to treat the nickel(II)
complex with dimethylglyoxime and aqueous ammonia
at room temperature. The ligand C10H4-1,4-Ph2-2,3-
(PPh2)2 (13a ) that is released quantitatively can be
obtained pure by filtration through degassed acidic
alumina. The naphthylenebis(diphenylphosphines) are
air-stable, yellow solids that show singlet 31P NMR
resonances at δ ca. -1 to -6 and parent ion peaks in
their electron-impact (EI) mass spectra.
Oxidation of both phosphorus atoms requires forcing
conditions. The nickel(0) complexes 2a -4a and 2b-4b
or the derived tertiary phosphines 12a ,b had to be
treated with 30% aqueous H2O2 or heated in the
presence of air in order to obtain the bis(diphenylphos-
phine oxides), 6,7-X2C10H2-1,4-Me2-2,3-{P(O)Ph2}2 (X )
H (14a ), F (14b)), quantitatively.
Exposure of the mixtures of nickel(0) complexes 2a -
4a and 2b -4b to air over 24 h gives exclusively the
colorless mono(diphenylphosphine oxides) 6,7-X2C10H2-
1,4-Me2-2-PPh2-3-{P(O)Ph2} (X ) H (15a ), F (15b)),
which show 31P NMR doublet resonances at δ ca. -6
(PPh2) and +31 [P(O)PPh2] (2J PP ) 37 Hz) and parent
ion peaks in their EI mass spectra (eq 3). The formula-
tion of 15b has been confirmed by X-ray structural
analysis.16
(3)
(PPh2)3-4-{P(O)PPh2}-κP1,P2}]; this formulation has
been confirmed by X-ray structural analysis (see below).
The total yield for the double-insertion reaction calcu-
lated from the recovered products 16-18 was ca. 90%,
based on the Ni(II) precursor to 1a , [NiBr(2-C6H4)-
(PEt3)2]; hence, little or no material had been lost on
the silica gel column. The predominant formation of 18
as a result of chromatography can only be accounted
for by mono-oxidation of 16 and 17 on the column
accompanied by migration of the NiBr2 fragment from
phosphorus atoms P2 and P3 to P1 and P2. The observa-
tion that the relative amounts of 16 and 17 before
chromatography do not change on heating suggests that
the rearrangement is preceded, not followed, by oxida-
tion of P4.
Treatment of the mixture of 16 and 17 with dimeth-
ylglyoxime in the presence of aqueous ammonia pre-
cipitates immediately the crude tetrakis(tertiary phos-
phine) C10H4-1,2,3,4-(PPh2)4 (19), whose 31P{1H} NMR
spectrum shows a pair of triplets at δ -10.8 and 4.5
due to P1,4 and P2,3, respectively. Unfortunately, at-
tempts to crystallize 19 gave only partially oxidized
material, single crystals of which contained a 73:27
mixture of the bis(diphenylphosphine oxides) C10H4-1,4-
(PPh2)2-2,3-{P(O)Ph2}2 (20) and C10H4-3,4-(PPh2)2-1,2-
{P(O)Ph2}2 (21), as shown by X-ray structural analysis
(see below).
(2) Bis(d ip h en ylp h osp h in o)a cetylen e, P h 2P Ct
CP P h 2. Double insertion of Ph2PCtCPPh2 with [Ni-
(η2-C6H4)(PEt3)2] (1a ) (Scheme 3) required heating at
50 °C for 16 h. The 31P{1H} NMR spectrum of the
resulting solution is complex, although addition of
bromine simplifies it. The crude orange solid isolated
from the brominated solution contains the dibromon-
ickel(II) complexes of two isomeric naphthalene-based
ligands in a 2:1 ratio. The 31P{1H} NMR spectrum of
the major species contains two doublets of doublets at
δP -12.2 and 75.8, a pattern that is consistent with a
symmetrical chelate complex having uncoordinated
diphenylphosphino groups in the 1,4-positions, i.e.,
[NiBr2{C10H4-1,2,3,4-(PPh2)4-κP2,P3}] (16). The minor
compound is less symmetrical: its 31P{1H} NMR spec-
trum shows four different resonances at δ -9.4, 3.8,
66.9, and 81.9, the first two being assigned to phospho-
rus atoms at positions 4 and 3, the last two to coordi-
nated phosphorus atoms at positions 1 and 2. The
chemical shifts and coupling constants are consistent
with the formulation [NiBr2{C10H4-1,2,3,4-(PPh2)4-
κP1,P2}] (17). Attempts to separate 16 and 17 on silica
gel gave small amounts of the original mixture together
with a new complex 18, whose 31P{1H} NMR spectrum
resembles that of 17 except that the resonances due to
the uncoordinated phosphorus atoms P3 and P4 are
shifted to δ 13.5 and 29.4, respectively. The IR spectrum
contains a strong absorption at 1208 cm-1 assignable
to ν(PdO), and the mass spectrum shows that one of
the uncoordinated phosphorus atoms has been oxidized.
The data indicate that complex 18 is [NiBr2{C10H4-1,2,3-
(3) Eth yn ylp h osp h in e, P h 2P CtCH. This ligand
reacts with the 4,5-difluorobenzyne complex 1b to give
a dark red solution whose 19F and 31P NMR spectra are
very complex. The 31P{1H} NMR spectrum contains
signals similar to those described above corresponding
to nickel(0) complexes of naphthylene-2,3-bis(diphe-
nylphosphines), but there are also signals in the region

1526 Organometallics, Vol. 19, No. 8, 2000
Bennett et al.
of δP -5 that are likely to be due to free naphthylenebis-
(diphenylphosphines), together with multiplets possibly
due to phosphine oxides or oligomers. The 31P{1H} NMR
spectrum of the solution obtained after addition of
bromine is also complex, although a resonance at δP 65.2
due to a minor component may be assigned to the pla-
nar chelate nickel(II) complex [NiBr2{6,7-F2C10H4-2,3-
(PPh2)2}] (22). The main species present shows a very
broad signal at δP 38 and gives a green solution in CH2-
Cl2 suggestive of the presence of a paramagnetic,
tetrahedrally coordinated nickel(II) complex, but we
could not characterize it.
F igu r e 1. Molecular structure of 11b with selected atom
labeling. Thermal ellipsoids show 30% probability levels;
hydrogen atoms have been omitted for clarity.
Treatment of the nickel(0) complexes arising from
reaction with Ph2PCtCH with air and subsequently
with H2O2 gives a mixture whose 19F NMR spectrum
shows the presence of only three aromatic compounds
in a ratio of ca. 1:2:1. The components of the mixture
could not be separated by chromatography, but some
tentative assignments can be made. The first compound,
which shows a triplet at δF -131.7 and a singlet in the
31P{1H} NMR spectrum at δ 31.0, is probably the 2,3-
naphthylenebis(diphenylphosphine oxide) 6,7-F2C10H4-
2,3-{P(O)Ph2}2 (23); the most abundant species contains
a pair of multiplets at δ -129.4 and -133.4 in its 19F
NMR spectrum and a pair of doublets at δ 31.5 and 26.3
(J ) 2.3 Hz) in its 31P{1H} NMR spectrum. These data
suggest that the compound is the 1,3-naphthylenebis-
(diphenylphosphine oxide) 6,7-F2C10H4-1,3-{P(O)Ph2}2
(24); the ligand from which it is derived, 6,7-F2C10H4-
1,3-(PPh2)2, is clearly incapable of chelation to a single
nickel(II) atom and is likely to be responsible for the
formation of the paramagnetic nickel(II) species men-
tioned above. The nature of the third species, which is
responsible for a pair of multiplets at -130.5 and -133.7
in the 19F NMR spectrum, is unknown.
F igu r e 2. Molecular structure of 18 with selected atom
labeling. Thermal ellipsoids show 30% probability levels;
hydrogen atoms have been omitted for clarity.
The double insertion of Ph2PCtCH with 1b is clearly
not regiospecific and, hence, synthetically not very
useful. This reaction has therefore not been studied
further.
squares plane defined by Ni(1), Br(1), Br(2), P(1), and
P(2) in 11 being only 0.038 Å. In 18, the phosphorus
atoms P(1) and P(2) lie 0.1585 and -0.1625 Å, respec-
tively, from that plane. In both complexes, the naph-
thalene ring is planar, the dihedral angles with the
coordination plane being 3.1° (11b) and 11.6° (18). Both
values are considerably smaller than the value of 26.2°
found in [NiBr2{6,7-F2C10H2-1,4-Me2-2,3-(PPh2)2}] (6b),16
probably reflecting the steric interaction between the
1,4-diphenyl substituents and the PPh2 groups in the
case of 11b and between the adjacent coordinated and
uncoordinated PPh2 groups in the case of 18, leading
in both cases to a flattening of the geometry. In
agreement, the 1,4-substituents in 11b are slightly bent
away from the PPh2 groups. The metal-ligand bond
Str u ctu r es Deter m in ed by X-r a y Cr ysta llogr a -
p h y. The molecular geometries of [NiBr2{6,7-F2C10H2-
1,4-Ph2-2,3-(PPh2)2}] (11b ) and [NiBr2{C10H4-1,2,3-
(PPh2)3-4-{P(O)PPh2}-κP1,P2}] (18) are shown, together
with the atom labeling, in Figures 1 and 2; selected
interatomic distances and angles for 6b, 11b, and 18
are listed in Tables 1-3, respectively (those for 6b were
not given in the preliminary communication16). The
nickel atom is bonded to the naphthylenebis(diphen-
ylphosphine) fragments via the phosphorus atoms on
C2 and C3 in the case of 11a and via those on C1 and C2
in the case of 18. As expected, in both complexes the
coordination geometry about the metal atom is close to
square planar, the mean deviation from the least-

Insertion of Phosphines into Ni(0) Benzyne Complexes
Organometallics, Vol. 19, No. 8, 2000 1527
Ta ble 1. Selected Bon d Len gth s (Å) a n d Bon d
An gles (d eg) for 6ba
Ni(1)-Br(1)
Ni(1)-P(1)
P(1)-C(2)
C(1)-C(2)
C(3)-C(4)
C(4)-C(10)
C(4)-C(12)
2.3400(8)
2.144(1)
1.829(4)
1.389(5)
1.377(5)
1.439(5)
1.495(6)
Ni(1)-Br(2)
Ni(1)-P(2)
P(2)-C(3)
C(2)-C(3)
C(1)-C(9)
C(1)-C(11)
2.3253(7)
2.144(1)
1.833(4)
1.428(5)
1.416(5)
1.496(6)
Br(1)-Ni(1)-Br(2)
Br(1)-Ni(1)-P(2)
C(2)-C(1)-C(11)
93.05(3) Br(1)-Ni(1)-P(1)
176.36(4) Ni(1)-P(1)-C(2)
91.28(4)
109.9(1)
124.0(4)
123.4(4)
C(3)-C(4)-C(12)
a
For the numbering scheme, refer to ref 16.
Ta ble 2. Selected Bon d Len gth s (Å) a n d Bon d
An gles (d eg) for 11b
Ni(1)-Br(1)
Ni(1)-P(1)
P(1)-C(2)
C(1)-C(2)
C(3)-C(4)
C(4)-C(10)
C(4)-C(17)
2.336(2)
2.143(2)
1.854(7)
1.38(1)
1.39(1)
1.43(1)
1.49(1)
Ni(1)-Br(2)
Ni(1)-P(2)
P(2)-C(3)
C(2)-C(3)
C(1)-C(9)
C(1)-C(11)
2.331(2)
2.127(2)
1.836(7)
1.42(1)
1.43(1)
1.49(1)
Br(1)-Ni(1)-Br(2)
Br(1)-Ni(1)-P(2)
C(2)-C(1)-C(11)
94.18(6) Br(1)-Ni(1)-P(1)
175.89(8) Ni(1)-P(1)-C(2)
89.40(7)
110.6(2)
123.9(7)
125.3(7)
C(3)-C(4)-C(17)
F igu r e 3. Molecular structure of 20 with selected atom
labeling. Thermal ellipsoids show 30% probability levels;
hydrogen atoms have been omitted for clarity.
Ta ble 3. Selected Bon d Len gth s (Å) a n d Bon d
An gles (d eg) for 18
Ni(1)-Br(1)
Ni(1)-P(1)
P(1)-C(1)
P(3)-C(3)
C(1)-C(2)
C(3)-C(4)
C(4)-C(5)
2.335(2)
2.124(3)
1.84(1)
1.851(8)
1.39(1)
1.42(1)
1.42(1)
Ni(1)-Br(2)
Ni(1)-P(2)
P(2)-C(2)
P(4)-C(4)
C(2)-C(3)
C(1)-C(10)
P(4)-O(1)
2.338(2)
2.137(3)
1.859(8)
1.85(1)
1.44(1)
1.44(1)
and P(3) also deviate considerably from this plane, the
dihedral angle between the planes P(2)-C(2)-C(3) and
P(3)-C(3)-C(2) being 42.2(13)°. Similar steric distor-
tions of the aromatic ring have been reported for
benzenes having more than two adjacent PPh2 groups,
e.g. for 1,2,3,4-tetrakis(diphenylphosphino)benzene and
its chalcogen adducts, which were studied by 31P NMR
spectroscopy,27 or for 1,2,3,5-tetrakis(diphenylthiophos-
phino)benzene, whose X-ray structure analysis showed
dihedral angles P-C-C-P of up to 70°.28
1.463(6)
Br(1)-Ni(1)-Br(2)
Br(1)-Ni(1)-P(1)
P(1)-C(1)-C(2)
P(3)-C(3)-C(2)
94.06(7) Br(1)-Ni(1)-P(2)
88.29(8)
110.6(3)
123.3(6)
119.1(6)
173.5(1)
116.0(6)
111.2(6)
Ni(1)-P(1)-C(1)
P(2)-C(2)-C(3)
P(4)-C(4)-C(3)
lengths in both complexes are similar to each other and
to those in 6b (Ni-Br, 2.333 Å (av) (6b), 2.335 Å (av)
(11b), 2.337 Å (av) (18); Ni-P, 2.144(1), 2.144(1) Å (6b),
2.143(2), 2.127(2) Å (11b), 2.124(3), 2.137(3) Å (18)). The
P-O bond length in 18 (1.463(6) Å) is comparable with
that of 6,7-F2C10H2-1,4-Me2-2-(PPh2)-3-{P(O)Ph2} (15b)
(1.489(5) Å)16 and with those in a wide range of tertiary
phosphine oxides.26
The unit cell of the crystal isolated from attempted
crystallization of the tetrakis(tertiary phosphine) 19
contains two isomeric bis(tertiary phosphine oxides),
C10H4-1,4-(PPh2)2-2,3-{P(O)PPh2}2 (20) (73% occupancy)
and C10H4-1,2-(PPh2)2-3,4-{P(O)PPh2}2 (21) (27% oc-
cupancy). The structure of 20 is shown in Figure 3.
Owing to disorder arising from the alternative locations
of an oxygen atom on P(1) or P(3), the bond lengths are
unreliable and are therefore not tabulated. However,
an interesting consequence of the steric crowding is that
the naphthalene units are not planar. The substituted
carbon atoms C(1), C(2), C(3), and C(4) are respectively
0.17(2), 0.31(3), 0.01(3), and -0.10(2) Å out of the plane
defined by the other carbon atoms (C(5)-C(10)) of the
naphthalene ring. As a consequence of the steric repul-
sion between O(2) and O(3), the phosphorus atoms P(2)
Discu ssion
The double insertion of (alkynyl)diphenylphosphines
into the nickel-carbon bonds of the benzyne complexes
1a and 1b leads to naphthalene-based diphenylphos-
phines and derived phosphine oxides that would be
difficult to make by conventional methods. In particular,
the reactions with Ph2PCtCR (R ) Me, Ph) occur with
high regioselectivity to give nickel(0) complexes contain-
ing the corresponding 2,3-naphthylenebis(diphenylphos-
phines) 6,7-X2C10H2-1,4-Y2-2,3-(PPh2)2 (X ) H, Y ) Me
(12a ); X ) F, Y ) Me (12b); X ) H, Y ) Ph (13a ); X )
F, Y ) Ph (13b)), which behave as bidentate ligands
and can be isolated from the reactions via their five-
membered-ring chelate NiBr2 complexes.29 Few ex-
amples of naphthalene-based bis(tertiary phosphines)
are known. The closest analogue is 1-phenylnaphtha-
lene-2,3-bis(diphenylphosphine), which is obtained via
its PtCl2 complex by thermal coupling of the pendant
alkynyl groups of cis-[PtCl2(Ph2PCtCPh)2].30,31 The
(27) McFarlane, H. C. E.; McFarlane, W. Polyhedron 1999, 18, 2117.
(28) Clegg, W.; Edwards, A. J .; McFarlane, H. C. E.; McFarlane,
W. Polyhedron 1998, 17, 3515.
(29) McAuliffe, C. A.; Levason, W. Phosphine, Arsine and Stibine
Complexes of the Transition Elements; Elsevier: Amsterdam, 1979.
(30) Carty, A. J .; Taylor, N. J .; J ohnson, D. K. J . Am. Chem. Soc.
1979, 101, 5422.
(26) Gilheany, D. C. In The Chemistry of Organophosphorus Com-
pounds; Hartley, F. R., Ed.; Wiley: Chichester, U.K., 1992; Vol. 2, p
10.

1528 Organometallics, Vol. 19, No. 8, 2000
Bennett et al.
Sch em e 4
favored insertion into the nickel-vinyl bond in the
second step on electronic grounds.9,12,14 However, DFT
calculations show nickel-vinyl and nickel-phenyl bonds
to be very similar in energy35 and, in this case, the
presence of the PPh2 group may tilt the balance in favor
of the nickel-phenyl bond. Thus, if the second insertion
occurs in the same sense as the first one, the product
will be the seven-membered nickelacycle 27. Many
examples of similar metallacycles that result from
insertion of an unsaturated substrate into a five-
membered nickelacycle are known.36 Reductive elimina-
tion from 27 then gives the appropriate naphthylene-
2,3-bis(diphenylphosphine), which will readily capture
the nickel(0) fragment to give the observed mixture of
nickel(0) complexes.
The double insertion of Ph2PCtCH is less regiose-
lective than those of Ph2PCtCR (R ) Me, Ph); a similar
trend is evident in the behavior of HCtCCO2Me and
MeCtCCO2Me.9,12 It seems likely that the first inser-
tion occurs with the same regioselectivity as those for
Ph2PCtCR to give the corresponding (2-diphenylphos-
phino)nickelaindene 26 (R ) H); cf. the reactions of Ph2-
PCtCR (R ) H, Ph) with [Cp2Zr(η2-C6H4)] (eq 1).17 Loss
of regiocontrol may occur in the second insertion,
perhaps as a result of competitive insertion with the
same regioselectivity into the nickel-phenyl and nickel-
vinyl bonds of the nickelaindene.
The formation of the η2-alkyne complexes 9a ,b and
10 is also of interest. In general, P-donor coordination
of (alkynyl)diphenylphosphines is favored kinetically
and there are numerous complexes or clusters in which
dppa acts as a bridging ligand through its phosphorus
atoms.37 Only a few compounds are known in which
alkyne coordination is favored over P-donor coordina-
tion, e.g. [Co2(CO)6{µ-η2-(C6F5)2PCtCR}] (R ) Me,
Ph),15a [(CpNi)2(µ-η2-Ph2PCtC-tBu)],38 and [W(CO)(η2-
Ph2PCtCPPh2)(S2CNEt2)2];39 more commonly the Ph2-
PCtCR ligands bridge a pair of metal atoms via
phosphorus and the triple bond, as in [Ni2(CO)2(µ-η1:
η2-Ph2PCtC-tBu)].38 In our case, although a P-coordi-
nated species may be an intermediate in the formation
of 10, the complex having the alkyne bonded to nickel
is clearly the thermodynamically favored species.
Finally, an interesting feature of the new naphthalene-
based bis(tertiary phosphines) is that they undergo
selective oxidation to mixed tertiary phosphine-phos-
phine oxide compounds when their nickel(0) complexes
are exposed to air. The only polyfunctional tertiary
phosphines known to undergo mono-oxidation in air are
o-phenylenebis(methylphenylphosphine), o-C6H4(PMe-
Ph)2,40 and 1,2,3,4-tetrakis(diphenylphosphino)benzene;
in the latter compound only the phosphorus atom
compounds 1,8-naphthylenebis(dimethylphosphine)32 and
1,8-naphthylenebis(diphenylphosphine)33 have been ob-
tained from the reaction of 1,8-dilithionaphthalene with
the appropriate phosphinous chloride; the second com-
pound forms six-membered-ring chelate complexes with
PtCl2 and PdCl2.
In view of the bulk of the PPh2 group, the regioselec-
tivity observed with Ph2PCtCR (R ) Me, Ph) cannot
be determined primarily by steric effects but must result
from electronic control. The regioselectivity is similar
to that with methyl 2-butynoate, MeCtCCO2Me, whose
double insertion with 1a and 1b is also believed to be
under electronic control.12,14 The similarity in the direct-
ing effects of PPh2 and CO2Me as substituents on a Ct
C bond is supported by theoretical calculations, which
show alkynylphosphines and acetylenic esters to be
polarized similarly, although there is no delocalization
of the π-system onto the phosphorus atom.34
A possible mechanism for the double insertion of Ph2-
PCtCR (R ) Me, Ph) into the nickel(0)-benzyne bond
of 1a is outlined in Scheme 4. In the first step, the
alkynylphosphine displaces a PEt3 ligand to give a η2-
alkyne complex (25), analogous to the spectroscopically
detected complexes 9a and 9b, and to 10. The first
insertion, resulting from attack of the nucleophilic
benzyne complex on the electrophilic carbon atom of the
alkyne, then gives the five-membered nickelacycle 26,
in which the carbon atom bearing the PPh2 group is
attached to nickel, i.e., a (2-diphenylphosphino)nick-
elaindene, analogous to the similarly prepared (2-
diphenylphosphino)zirconaindene (eq 1).17
(35) Macgregor, S. A. Preliminary calculations, Heriot-Watt Uni-
versity, Edinburgh, U.K.
(36) Ca´mpora, J .; Palma, P.; Carmona, E. Coord. Chem. Rev. 1999,
193-195, 207.
(37) (a) Orama, O. J . Organomet. Chem. 1986, 314, 273 and
references therein. (b) Hogarth, G.; Norman, T. Polyhedron 1996, 15,
2859 and references therein. (c) Sappa, E. J . Organomet. Chem. 1988,
352, 327.
The second insertion can take place in either the
nickel-vinyl or nickel-phenyl bond of 26. In the cor-
responding reaction of MeCtCCO2Me with 1b, we
(38) Paik, H. N.; Carty, A. J .; Dymock, K.; Palenik, G. J . J .
Organomet. Chem. 1974, 70, C17.
(39) (a) Ward, B. C.; Templeton, J . L. J . Am. Chem. Soc. 1980, 102,
1532. (b) Nickel, T. M.; Wau, S. Y. W.; Went, M. J . J . Chem. Soc., Chem.
Commun. 1989, 775. (c) Powell, A. K.; Went, M. J . J . Chem. Soc.,
Dalton Trans. 1992, 439.
(31) J ohnson, D. K.; Rukachaisirikul, T.; Sun, Y.; Taylor, N. J .;
Canty, A. J .; Carty, A. J . Inorg. Chem. 1993, 32, 5544.
(32) Costa, T.; Schmidbaur, H. Chem. Ber. 1982, 115, 1374.
(33) J ackson, R. D.; J ames, S.; Orpen, A. G.; Pringle, P. G. J .
Organomet. Chem. 1993, 458, C3.
(34) Louattani, E.; Lledo´s, A.; Suades, J .; Alvarez-Larena, A.;
Piniella, J . F. Organometallics 1995, 14, 1053.
(40) Wild, S. B. Personal communication, Australian National
University.

Insertion of Phosphines into Ni(0) Benzyne Complexes
Organometallics, Vol. 19, No. 8, 2000 1529
bonded to C1 is oxidized.27 Bis(tertiary phosphine)
monoxides are potentially useful ligands for some
homogeneously catalyzed processes, yet few satisfactory,
general synthetic methods are available.41 The selectiv-
ity to air oxidation in the case of the naphthalene-based
ligands may result from steric protection and electronic
deactivation of one phosphorus atom induced by oxida-
tion at its rigidly held neighbor or from a selective mono-
oxidation induced by the presence of the chelated
nickel(0) center. As the free naphthylenebis(diphe-
nylphosphines) are quite resistant to aerial oxidation,
the latter mechanism is favored.
MHz, C6D6): δ 4.9 (s, CH3), 76.4 (s, CH3CtC), 106.1 (s, CH3Ct
C), 128.7 (d, J (PC) 7.7, CH), 129.0 (s, CH), 132.9 (d, J (PC) 21.0,
CH), 137.73 (d, J (PC) 8.0, C).
P h 2P (O)CtCMe. 31P{1H} NMR (81.0 MHz, C6D6): δ 7.3
(s).
1
P h 2P CtCP h . H NMR (300 MHz, C6D6): δ 6.84-6.94 (m,
3H, Ar H), 7.00-7.11 (m, 6H, Ar H), 7.31-7.36 (m, 2H, Ar H),
7.73-7.80 (m, 4H, Ar H). 13C{1H} NMR (75.4 MHz, C6D6): δ
86.6 (d, J (CP) 8.9, PhCtC), 108.1 (d, J (CP) 4.5, PhCtC), 122.9
(C), 128.2 (CH), 128.6 (d, J (PC) 7.5), 128.6, 128.9, 131.8 (CH),
132.7 (d, J (PC) 21.5, CH), 136.6 (d, J (PC) 7.1, C). 31P{1H} NMR
(81.0 MHz, C6D6): δ -32.5 (s).
1
P h 2P CtC-t-Bu . H NMR (300 MHz, C6D6): δ 1.36 (s, 9H,
C(CH3)3), 7.31-7.39 (m, 6H, Ar H), 7.58-7.66 (m, 4H, Ar H).
31P{1H} NMR (81.0 MHz, C6D6): δ -34.0 (s).
Exp er im en ta l Section
P h 2P (O)CtC-t-Bu . 31P{1H} NMR (81.0 MHz, C6D6): δ 5.1
(s).
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 81.0 MHz), a Varian Gemini-300 BB (1H at 300
MHz, 13C at 75.4 MHz, and 31P at 121.4 MHz), or a Varian
Inova-500 instrument (1H at 500 MHz, 13C at 125.7 MHz, and
31P at 202.4 MHz). The chemical shifts (δ) for 1H and 13C are
given in ppm relative to residual signals of the solvent and to
external 85% H3PO4 for 31P. The spectra of all nuclei (except
P h 2P CtCH. 1H NMR (300 MHz, C6D6): δ 2.68 (d, 1H,
1J (PH) 2.48, CtCH), 6.9-7.05 (m, 6H, Ar H), 7.59-7.67 (m,
4H, Ar H). 31P{1H} NMR (81.0 MHz, C6D6): δ -33.3 (s). 13C-
{1H} NMR (75.4 MHz, C6D6): δ 96.6 (br s, HCtC), 111.1 (s,
HCtC), 128.9 (d, J (PC) 9.4, CH), 129.3 (s, CH), 133.0 (d, J (PC)
24.0, CH), 136.1 (d, J (PC) 8.3, C).
P h 2P (O)CtCH. 31P{1H} NMR (81.0 MHz, C6D6): δ 5.6 (s).
((Tr im eth ylsilyl)eth yn yl)d ip h en ylp h osp h in e, P h 2P Ct
CSiMe3. This oil was prepared similarly to Ph2PCtC-t-Bu45
by deprotonation of Me3SiCtCH with n-BuLi at -78 °C and
reaction of the resulting lithioacetylide with Ph2PCl. 1H NMR
(300 MHz, C6D6): δ 0.13 (s, 9H, CH3), 6.96-7.09 (m, 6H, Ar
H), 7.70-7.77 (m, 4H, Ar H). 13C{1H} NMR (75.4 MHz, C6D6):
δ -0.1 (s, CH3), 103.3 (d, J (CP) 13.2, Me3SiCtC), 117.4 (s,
Me3SiCtC), 129.0 (d, J (PC) 7.7), 129.5 (s), 132.8 (d, J (PC) 20.9,
CH), 136.5 (d, J (PC) 6.6, C). 31P{1H} NMR (81.0 MHz, CD2-
Cl2): δ -31.1 (s).
1
1H and 19F) were H-decoupled. The coupling constants (J ) are
given in Hz. Infrared spectra were measured on Perkin-Elmer
683 or FT-1800 instruments. Mass spectra were obtained on
a Fisons VG ZAB2-SEQ spectrometer by the fast-atom bom-
bardment (FAB) technique, on a Fisons VG Autospec spec-
trometer by electron impact (EI), or on a Fisons VG Quattro
II by electrospray (ESI). Microanalyses were done in-house.
In several cases, especially for the tertiary phosphines and
phosphine oxides, the uninformative 1H and 13C NMR spectra,
which consist of broad multiplets in the aromatic region δH
6.8-8.5 and δC 122-135, are not reported in detail.
Sta r tin g Ma ter ia ls. 1,2-Dibromobenzene, 1,2-dibromo-4,5-
difluorobenzene, acetylene (ethyne), phenylacetylene, propyne,
3,3-dimethyl-1-butyne, bis(diphenylphosphino)acetylene (dppa),
and (trimethylsilyl)acetylene were obtained commercially and
used as received. Chlorodiphenylphosphine was obtained
commercially and distilled under an inert, reduced-pressure
atmosphere before use. The aryl-nickel(II) complexes [NiBr-
(2-Br-4,5-X2C6H2)(dcpe)] (X ) H, F) were prepared by zinc
reduction of [NiBr2(PPh3)2]42 in the presence of the appropriate
1,2-dibromoarene and subsequent replacement of PPh3 by
dcpe. The complexes [NiBr(2-Br-4,5-X2C6H2)(PEt3)2] (X ) H,
F) were prepared by reaction of [Ni(COD)2]43 with the corre-
sponding dibromoarene in the presence of 2.5 equiv of PEt3.12
The complex [Ni(C2H4)(dcpe)] was prepared as described
previously.44
In ser tion Rea ction s of P h 2P CtCMe w ith [Ni{(1,2-η)-
4,5-X2C6H2}(P Et3)2] (X ) H (1a ), F (1b)). A filtered, yellow
solution of 1a in hexane (30 mL), prepared by reduction of
[NiBr(2-BrC6H4)(PEt3)2] (531 mg, 1 mmol) with lithium (231
mg, 10 mmol, 30% dispersion in paraffin) in ether at -40 °C,12
was cooled to -78 °C. A solution of diphenyl-1-propynylphos-
phine (560 mg, 2.5 mmol) in hexane (5 mL) was added. The
initially formed orange suspension was then warmed to room
temperature, and the resulting dark red solution was stirred
at room temperature for a further 4 h. The 31P{1H} NMR
spectrum showed the presence of three nickel(0) complexes of
general formula [Ni{C10H4-1,4-Me2-2,3-(PPh2)2}(L1)(L2)] (L1 )
L2 ) PEt3 (2a ), L1 ) L2 ) Ph2PCtCMe (3a ), L1 ) PEt3 and L2
) Ph2PCtCMe (4a )), together with free PEt3 and Ph2PCt
CMe. The relative ratio of the complexes changes from one
experiment to the other, depending on the excess of Ph2PCt
CMe present.
2a . 31P{1H} NMR (81.0 MHz, C6D6): δ 10.9 (t, J (PP) 25.6,
2
2
PEt3), 50.9 (t, J (PP) 25.6, C12H10(PPh2)2).
3a . 31P{1H} NMR (81.0 MHz, C6D6): δ 7.9 (t, 2J (PP) 22.8,
The (alkynyl)diphenylphosphines Ph2PCtCR (R ) H, Me,
Ph, t-Bu) were prepared by following the published proce-
dures.45,46 Complete NMR data for these compounds have not
been published; they are given below, together with some
values for the corresponding oxides.
P h 2P CtCMe. 1H NMR (300 MHz, C6D6): δ 1.53 (s, 3H,
CH3), 7.02-7.11 (m, 6H, Ar H), 7.64-7.67 (m, 4H, Ar H). 31P-
{1H} NMR (81.0 MHz, C6D6): δ -31.4 (s). 13C{1H} NMR (75.4
2
Ph2PCtCMe), 51.5 (t, J (PP) 22.8, C12H10(PPh2)2).
4a . 31P{1H} NMR (81.0 MHz, C6D6): δ 5.6 (dt, J (PP) 41.2,
2
25.4, Ph2PCtCMe), 10.1 (dt, 2J (PP) 41.2, 21.6, PEt3), 51.2 (dd,
2J (PP) 25.4, 21.6, C12H10(PPh2)2).
A similar reaction was carried out with the 4,5-difluoroben-
zyne complex 1b; 31P{1H} NMR monitoring showed the forma-
tion of the corresponding 6,7-difluoro-substituted nickel(0)
complexes 2b-4b, whose 31P NMR spectroscopic data were
similar to those of 2a -4a .
[Ni{6,7-X2C10H2-1,4-Me2-2,3-(P P h 2)2}(d cp e)] (X ) H (5a ),
F (5b)). In qualitative reactions, dcpe (small excess) was added
to solutions containing 2a -4a and 2b-4b, and the mixtures
were stirred for 2 h at room temperature. The 31P{1H} and
19F NMR spectra indicated the formation of 5a or 5b, together
with free PEt3 and Ph2PCtCMe. Complex 5a was isolated as
a beige solid by removing the solvent in vacuo and washing
(41) Grushin, V. V. J . Am. Chem. Soc. 1999, 121, 5831.
(42) Venanzi, L. M. J . Chem. Soc. 1958, 719.
(43) Schunn, R. A. Inorg. Synth. 1974, 15, 5.
(44) Bennett, M. A.; Hambley, T. W.; Roberts, N. K.; Robertson, G.
B. Organometallics 1985, 4, 1992.
(45) Charrier, C.; Chodkiewicz, W.; Cadiot, P. Bull. Soc. Chim. Fr.
1966, 1002.
(46) Carty, A. J .; Hota, N. K.; Ng, T. W.; Patel, H. A.; O’Connor, T.
J . Can. J . Chem. 1971, 49, 2706.

1530 Organometallics, Vol. 19, No. 8, 2000
Bennett et al.
with hexane. The compound was not analytically pure, but
attempts to crystallize it were unsuccessful owing to its poor
solubility.
resulting residue in acetone (5 mL) gave a solution which was
confirmed by 31P{1H} NMR spectroscopy to contain 14a as the
only naphthalene-based product, together with the phosphine
oxides of the auxiliary ligands. Extraction with benzene and
crystallization gave pure 14a as a colorless solid. 1H NMR (200
MHz, C6D6): δ 2.48 (br s, 6H, CH3), 6.85-7.15 (m, 12H), 7.28
([AB]m, 2H), 7.65-7.85 (m, 8H). 31P{1H} NMR (81.0 MHz, d6-
acetone): δ 34.3 (br s). EI-MS (C36H30O2P2): m/z 556 (32, M+),
479 (100, M+ - Ph). High-resolution MS: calcd for C36H30O2P2,
556.172 107; found, 556.171 083. Anal. Calcd for C36H30O2P2:
C, 77.69; H, 5.43. Found: C, 77.71; H, 5.57.
5a . 1H NMR (300 MHz, C6D6): δ 1.15-2.15 (m, 48H, dcpe),
2.29 (6H, CH3), 6.80-7.25 (m, 14H), 7.75 ([AB]m, 2H), 7.97-
8.05 (m, 8H). 31P{1H} NMR (81.0 MHz, C6D6): δ 47.2 (t, 2J (PP)
26.6), 52.1 (t, 2J (PP) 26.6). FAB-MS (C62H78NiP4, tetraglyme):
m/z 1004 (20, M+). High-resolution MS: calcd for C62H78NiP4,
1004.440 754; found, 1004.444 885.
5b. 31P{1H} NMR (81.0 MHz, C6D6): δ 47.4 (t, 2J (PP) 27.4),
52.3 (t, 2J (PP) 27.4). 19F NMR (188.1 MHz, C6D6): δ -139.6
(app t, J (FH) 10.2).
The analogous 6,7-difluoro-substituted bis(phosphine oxide)
14b was formed similarly. IR (KBr disk): ν(PdO) 1118 cm-1
.
[NiBr 2{6,7-X2C10H2-1,4-Me2-2,3-(P P h 2)2}] (X ) H (6a ), F
(6b)). A solution of bromine (0.15 mL, 2.9 mmol) in hexane (5
mL) was added dropwise over 5 min to a solution containing
2a -4a (1 mmol) at -30 °C (prepared as described above), and
the mixture was stirred for 2 h at room temperature. Filtration
of the resulting orange precipitate in air afforded the nickel-
(II) complex 6a (696 mg, 95% yield based on the nickel(II)
31P{1H} NMR (81.0 MHz, d6-acetone): δ 33.4 (br s). 19F NMR
(188.1 MHz, C6D6): δ -133.9 (br). EI-MS (C36H28F2O2P2): m/z
592 (36, M+), 515 (100, M+ - Ph).
6,7-X2C10H2-1,4-Me2-2,3-(P P h 2)2 (X ) H (12a ), F (12b)).
A solution of [NiBr2{C10H4-1,4-Me2-2,3-(PPh2)2}] (6a ; 218 mg,
0.29 mmol) in DMSO (20 mL) was treated with NaCN (575
mg, 11.7 mmol), and the mixture was heated to 60 °C overnight
with stirring. After addition of hexane (25 mL) and distilled
water (20 mL), separation and evaporation of the organic phase
afforded 12a quantitatively as a yellow solid. 1H NMR (200
MHz, C6D6): δ 2.28 (s, 6H, CH3), 6.95-7.15 (m, 12H), 7.23
([AB] m, 2H), 7.45-7.55 (m, 8H), 7.77 ([AB] m, 2H). 13C{1H}
NMR (75.4 MHz, C6D6): δ 20.5 (CH3), 125.3, 126.9, 127.6 (CH),
128.6 (t, 3J (CP) 2.7, CH), 132.0 (t, 2J (CP) 8.9, CH), 135.3
1
precursor). H NMR (300 MHz, CD2Cl2): δ 2.21 (s, 6H, CH3),
7.37-7.50 (m, 12H, Ar H), 7.89-7.98 (m, 8H, Ar H), 7.66-
8.05 (m, 4H, Ar H). 31P{1H} NMR (81.0 MHz, CD2Cl2): δ 65.5
(s). EI-MS (C36H30Br2NiP2): m/z 663 (100, M+ - Br). Anal.
Calcd for C36H30Br2NiP2: C, 58.18; H, 4.04; P, 8.35. Found:
C, 58.40; H, 4.24; P, 8.85.
In a similar reaction, the mixture of nickel(0) complexes 2b-
4b was treated with bromine to give 6b in 97% yield (based
on the nickel(II) precursor). Single crystals suitable for X-ray
1
2
(C4a,8a), 137.9 (t, J (CP) 4.4, Cphenyl), 139.5 (t, J (CP) 4.4, C1,4),
140.8 (t, J (CP) 18.1, C2,3). 31P{1H} NMR (81.0 MHz, C6D6): δ
1
diffraction were obtained from CH2Cl2/hexane. H NMR (300
-5.6 (s). EI-MS (C36H30P2): m/z 524 (58, M+), 447 (100, M+
-
MHz, CD2Cl2): δ 2.18 (s, 6H, CH3), 7.46-7.59 (m, 12H, Ar H),
1
7.81 (t, J (FH) 10.1, 2H, Ar H), 7.91-7.98 (m, 8H, Ar H). 13C-
Ph). High-resolution MS: calcd for C36H30P2, 524.182 278;
found, 524.181 939.
The analogous compound 6,7-F2C10H2-1,4-Me2-2,3-(PPh2)2
(12b) was liberated quantitatively from 6b in the same way.
31P{1H} NMR (81.0 MHz, C6D6): δ -5.6 (s).19F NMR (188.1
{1H} NMR (75.4 MHz, CD2Cl2): δ 20.38 (CH3), 112.23 (m, CH),
129.16 (t, J (CP) 5.6, CH), 131.53 (CH), 133.07 (t, J (CP) 4.8,
CH), 133.34, (t, J (CP) 6.3, C1,4), 135.20 (t, J (CP) 46.5, Cphenyl),
140.22 (t, J (CP) 9.7, C2,3), 151.55 (br dd, J 281, 24, CF); C4a,8a
not located. 31P{1H} NMR (81.0 MHz, CD2Cl2): δ 65.8 (s). 19F
NMR (188.1 MHz, CD2Cl2): δ -132.6 (app t, J (FH) 10.1). EI-
MS (C36H28Br2F2NiP2): m/z 778 (46, M+), 697 (65, M+ - Br),
504 (100). Anal. Calcd for C36H28Br2F2NiP2: C, 55.50; H, 3.62;
Br, 20.51. Found: C, 55.36; H, 3.66; Br, 20.33.
MHz, C6D6): δ -138.5 (app t, J (FH) 10.3). EI-MS (C36H28
-
F2P2): m/z 560 (64, M+), 483 (100, M+ - Ph).
Elemental analyses of 12a and 12b were unsatisfactory
because the compounds tenaciously retain organic solvents.
Rea ction of P h 2P CtCP h w ith [Ni{(1,2-η)-4,5-X2C6H2}-
(P Et3)2] (X ) H (1a ), F (1b)). The reaction was carried out
as described for Ph2PCtCMe using 1a , formed from reduction
of [NiBr(2-BrC6H4)(PEt3)2] (538 mg, 1 mmol), and Ph2PCtCPh
(550 mg, 1.9 mmol). 31P{1H} NMR monitoring showed the
initial formation of [Ni{C10H4-1,4-Ph2-2,3-(PPh2)2}(L1)(L2)] (L1
) L2 ) PEt3 (7a ), L1 ) PEt3 and L2 ) Ph2PCtCPh (8a )),
together with free PEt3. Complex 7a formed first, but after 1
h at room temperature 8a was the major compound. After 3
h, these compounds had disappeared and [Ni{C10H4-1,4-Ph2-
2,3-(PPh2)2}(η2-Ph2PCtCPh)] (9a ) was the main product. 31P-
6,7-X2C10H2-1,4-Me2-2-P P h 2-3-{P (O)P h 2} (X ) H (15a ), F
(15b)). Ether (20 mL, nondegassed) was added to a mixture
of 2a -4a (prepared as described above), and the mixture was
stirred for 24 h in air at room temperature. During this time,
the dark red solution changed to clear yellow. Removal of all
volatiles in vacuo and dissolution of the residue in acetone (5
mL) gave a solution that was confirmed by 31P{1H} NMR spec-
troscopy to contain 15a as the only naphthalene-based product,
together with the phosphine oxides of the auxiliary ligands.
1H NMR (200 MHz, C6D6): δ 2.25 (s, 3H, CH3), 2.79 (s, 3H,
CH3), 6.85-7.95 (m, 24H). 31P{1H} NMR (81.0 MHz, d6-ace-
tone): δ -6.6 (d, 3J (PP) 37.4), 31.0 (d, 3J (PP) 37.4). EI-MS
(C36H30OP2): m/z 540 (29, M+), 422 (100, M+ - Ph), 314 (45,
M+ - PPh2).
The 6,7-difluoro analogue 6,7-F2C10H2-1,4-Me2-2-PPh2-3-{P-
(O)Ph2} (15b) was prepared similarly by exposure of a solution
of 2b-4b to air. Dissolution of the residue in acetone and slow
evaporation of the solution gave single crystals of 15b suitable
for X-ray diffraction. 1H NMR (300 MHz, CDCl3): δ 2.11 (s,
3H, CH3), 2.75 (s, 3H, CH3), 6.90-8.00 (m, 22H). 31P{1H} NMR
(81.0 MHz, d6-acetone): δ -6.3 (d, 3J (PP) 36.7), 31.0 (d, 3J (PP)
36.7). 19F NMR (188.1 MHz, C6D6): δ -135.3 (m) -136.0 (m).
EI-MS (C36H28F2OP2): m/z 576 (40, M+), 499 (100, M+ - Ph),
391 (38, M+ - PPh2). High-resolution MS: calcd for C36H28F2-
OP2, 576.158 834 9; found, 576.158 054.
{1H} NMR (81.0 MHz, C6D6): 7a , δ 6.7 (m, PEt3), 51.8 (m,
2
C
12H10(PPh2)2); 8a , δ 3.4 (dt, J (PP) 47.8, 21.5, Ph2PCtCPh),
7.4 (dt, 2J (PP) 47.8, 23.8, PEt3), 52.3 (app t, J (PP) 22.6, C12H10
-
(PPh2)2); 9a , δ -19.4 (dd, 3J (PP) 32.9, 29.4, Ph2PCtCPh), 61.6
(dd, 2J (PP) 32.4, 3J (PP) 29.6, C22H14(PPh2)2), 63.5 (app t, J (PP)
32.8, C22H14(PPh2)2).
A similar reaction was carried out using [NiBr(2-Br-4,5-
F2C6H2)(PEt3)2] (567 mg, 1 mmol) and Ph2PCtCPh (570 mg,
2 mmol). 31P{1H} NMR monitoring of the insertion showed the
formation of products with spectroscopic parameters similar
to those of 7a and 8a , together with [Ni{6,7-F2C10H2-1,4-Ph2-
2,3-(PPh2)2}(η2-Ph2PCtCPh)] (9b) as the major compound.
3
9b: 31P{1H} NMR (81.0 MHz, C6D6) δ -19.2 (dd, J (PP) 33.3,
29.9, Ph2PCtCPh), 62.2 (dd, 2J (PP) 33.2, 3J (PP) 29.9, C22H12F2-
(PPh2)2), 63.5 (app t, J (PP) 33.3, C22H12F2(PPh2)2).
6,7-X2C10H2-1,4-Me2-2,3-{P (O)P h 2}2 (X ) H (14a), F (14b)).
An excess of aqueous H2O2 (30 vol, 10 mL) was added to a
solution containing 2a -4a (prepared as described above), and
the mixture was stirred for 24 h in air at room temperature.
During this time, the dark red solution changed to clear yellow.
Removal of all volatiles in vacuo and dissolution of the
[NiBr 2{6,7-X2C10H2-1,4-P h 2-2,3-(P P h 2)2}] (X ) H (11a ),
F (11b)). Addition of a solution of bromine (0.15 mL) in THF
(10 mL) to a solution of 7a -9a (1 mmol) at -30 °C, followed
by stirring for 16 h at room temperature, gave a beige
suspension in a greenish solution. The solution was decanted
and the solid purified by filtration through a silica gel column

Insertion of Phosphines into Ni(0) Benzyne Complexes
Organometallics, Vol. 19, No. 8, 2000 1531
(CH2Cl2). Removal of the solvent gave pure 11a as an orange-
red powder (570 mg, 66% yield based on Ni(II) precursor). The
compound was recrystallized from a CH2Cl2 solution layered
with hexane. 1H NMR (300 MHz, CD2Cl2): δ 6.35 (d, 4H, J
7.6), 6.89 (d, 4H, J 7.7), 7.10 ([AA′BB′]m, 2H), 7.20 (t, 2H, J
7.3), 7.27-7.38 (m, 10H), 7.44-7.56 (m, 12H). 13C{1H} NMR
(50.3 MHz, CD2Cl2): δ 127.55, 127.73, 128.02 (CH), 128.64 (t,
J 5.9, CH), 129.00, 130.52 (CH), 130.89 (t, J 1.7, CH), 131.32
(C), 133.11 (t, J 4.7, CH), 133.85 (t, J 46.4, P-Cphenyl), 136.30
(t, J 1.8, C4a,8a), 136.69 (t, J 2.8, C1,4), 147.64 (t, J 9.0, C2,3).
yield of double-insertion products, calculated from 16-18, was
90%, based on the Ni(II) precursor.
The first fraction eluted from the column, containing mainly
the isomeric mixture of 16 and 17, was treated with dimeth-
ylglyoxime (150 mg) in acetone (20 mL) and 10 drops of
concentrated aqueous NH4OH. A colorless solid was formed
immediately. The solution was decanted, and the residue was
extracted with DMSO. Addition of hexane and stirring gave a
sticky solid which was identified as being the tetrakis(tertiary
phosphine) C10H4-1,2,3,4-(PPh2)4 (19). Attempted crystalliza-
tion from DMSO/ether gave a mixture of dioxides, 20 and 21,
identified by X-ray crystallography (see below).
16: 31P{1H} NMR (81.0 MHz, d6-acetone) δ -12.2 (dd, J (PP)
16.0, 11.8, P1,4), 75.8 (dd, J (PP) 16.0, 11.8, P2,3).
17: 31P{1H} NMR (81.0 MHz, d6-acetone) δ -9.4 (app t,
J (PP) 3.3, P4), 3.8 (d, J (PP) 26.9, P3), 66.9 (dd, 75.7, 3.7, P1),
81.9 (ddd, J (PP) 75.8, 27.0, 2.7, P2).
31P{1H} NMR (81.0 MHz, CD2Cl2): δ 66.7 (s). EI-MS (C46H34
-
Br2NiP2): m/z 787 (65, M+ - Br), 741 (35), 706 (40), 571 (95),
443 (52), 286 (100). Anal. Calcd for C46H34Br2NiP2‚CH2Cl2: C,
59.29; H, 3.81. Found: C, 59.44; H, 4.06.
The nickel(II) complex 11b was obtained similarly by
addition of a hexane solution of bromine to an aliquot of the
mixture of Ni(0) complexes 7b-9b prepared as described
above. Red single crystals suitable for X-ray diffraction were
obtained from CH2Cl2/hexane. 31P{1H} NMR (81.0 MHz, CD2-
Cl2): δ 67.1 (s). 19F NMR (188.1 MHz, CD2Cl2): δ -132.26 (app
t, J (FH) 10.3). FAB-MS (3-nitrophenyloctyl ether, C46H32Br2F2-
NiP2): m/z 902 (8, M+), 823 (100, M+ - Br). Anal. Calcd for
18: IR (KBr) 3052 (m), 1582 (w), 1479 (s), 1435 (s) 1208 (s,
PdO), 1111 (s), 1097 (s), 737 (vs), 692 (vs), 642 (vs) cm-1 31P-
;
{1H} NMR (81.0 MHz, d6-acetone) δ 13.5 (d, J (PP) 27.5, P3),
29.4 (d, J (PP) 3.9, P4), 64.9 (dd, J (PP) 76.9, 4.0, P1), 84.1 (dd,
J (PP) 76.8, 27.3, P2); FAB-MS (NBA, C58H44Br2NiOP4) m/z
1019 (38, M+-Br), 803 (100, C10H4(PPh2)3(OPPh2)).
19: 31P{1H} NMR (81.0 MHz, d6-DMSO) δ -10.8 (t, J (PP)
13.7, P1,4), 4.5 (t, J (PP) 13.7, P2,3).
C
46H32Br2F2NiP2‚2CH2Cl2: C, 53.71; H, 3.36; P, 5.78. Found:
C, 53.81; H, 3.95; P, 5.92.
6,7-X2C10H2-1,4-P h 2-2,3-(P P h 2)2 (X ) H (13a ), F (13b)).
Under nitrogen, a solution of [NiBr2{C10H4-1,4-Ph2-2,3-(PPh2)2}]
(11a ; 45 mg) in acetone was treated with an excess of
dimethylglyoxime (20 mg) and one drop of degassed concen-
trated aqueous NH4OH. After 3 h at room temperature, 31P
NMR spectroscopy showed the formation of 13a to be quan-
titative. The solvent was evaporated, the red solid was
extracted with benzene, and the resulting yellowish solution
was filtered through degassed silylated silica gel. Chromato-
graphic purification through degassed acidic alumina (ether)
Rea ction of P h 2P CtCH w ith [Ni{(1,2-η)-4,5-F 2C6H2}-
(P Et3)2] (1b). Both the reactions of 1a and 1b (1 mmol) with
2 equiv of Ph2PCtCH (420 mg, 2 mmol) gave very complicated
mixtures, as shown by 31P NMR spectroscopy. That obtained
from 1b was used in subsequent experiments.
A solution of bromine (0.15 mL, 2.9 mmol) in hexane (5 mL)
was added dropwise to the reaction mixture obtained from 1b.
The resulting orange precipitate was separated by filtration
and washed with hexane. The 31P NMR spectrum indicated
the presence of various dibromonickel(II) species (see text). The
peaks listed below are believed to be due to [NiBr2{6,7-F2C10H2-
2,3-(PPh2)2}] (22).
1
gave pure 13a as a yellow solid. H NMR (500 MHz, C6D6): δ
6.69 (t, 4H, J 7.8), 8.82-6.85 (m, 6H), 6.92 ([AA′BB′]m, 2H),
6.93-6.98 (m, 12H), 7.29-7.32 (m, 8H), 7.38 ([AA′BB′]m, 2H).
31P{1H} NMR (121.4 MHz, C6D6): δ -1.3 (s). 13C{1H} NMR
(125.7 MHz, C6D6): δ 126.51 (CH), 127.13 (t, J (CP) 27.4, CH),
127.66, 127.91 (CH), 128.07 (d, J (CP) 2.3, CH), 128.29, 130.67
(CH), 132.76 (t, J (CP) 10.3, CH), 136.30 (C), 137.57 (t, J (CP)
2.1, C), 139.38 (dd, J (CP) 14.4, 13.0, P-Cphenyl), 139.54 (C),
146.63 (t, J (CP) 5.1, C2,3). EI-MS (C46H34P2): m/z 648 (M+, 31),
571 (100). High-resolution MS: calcd for C46H34P2, 648.213 578;
found, 648.213 845.
22: 31P{1H} NMR (81.0 MHz, CD2Cl2) δ 65.8 (s); 19F NMR
(188.1 MHz, CD2Cl2) δ -132.6 (app t, J (FH) 10.1); EI-MS
(C36H28F2P2NiBr2) m/z 778 (46, M+), 697 (65, M+ - Br), 504
(100).
F or m a tion of [Ni(η2-P h 2P CtCP h )(d cp e)] (10). A sus-
pension of [Ni(C2H4)(dcpe)] (224 mg, 0.44 mmol) in ether (10
mL) was cooled to 0 °C under nitrogen. Ph2PCtCPh (126 mg,
0.44 mmol) was added as a solid, and the orange solution was
stirred for 0.5 h at room temperature. 31P{1H} NMR analysis
of the resulting yellow solution showed quantitative formation
of 10, which can be isolated as a yellow solid by layering the
solution with hexane. Although stable in solution, solid
The bis(phosphine) 13b was released from the dibromide
11b by heating with NaCN in DMSO as described for 12a .
31P{1H} NMR (81.0 MHz, C6D6): δ -6.9 (s). 19F NMR (188.1
MHz, C6D6): δ -137.9 (app t, J (FH) 10.2).
1
samples of 10 decompose on storage over a period of days. H
Rea ction betw een P h 2P CtCP P h 2 a n d [Ni(η2-C6H4)-
(P Et3)2] (1a ). A hexane solution of 1a , obtained from lithium
reduction of [NiBr(2-BrC6H4)(PEt3)2] (508 mg, 0.96 mmol), was
cooled to -60 °C. Bis(diphenylphosphino)acetylene (680 mg,
1.73 mmol) was added as a solid, followed by THF (10 mL).
The cold bath was removed, and the solution was stirred for 3
h and then heated at 50 °C for 16 h. After being cooled to -10
°C, the solution was treated with a solution of bromine (0.15
mL) in THF (10 mL) and the mixture was stirred for 2 h at
room temperature. The solvent was removed in vacuo. The
residue was extracted with THF, and the solution was filtered
through Celite. Removal of the solvent yielded a crude solid
containing [NiBr2{C10H4-1,2,3,4-(PPh2)4-κP2,P3}] (16) and [NiBr2-
{C10H4-1,2,3,4-(PPh2)4-κP1,P2}] (17) in a 2:1 ratio, together with
other phosphorus-containing products (as shown by 31P NMR
spectroscopy). Attempted separation on a degassed silica gel
column (CH2Cl2) gave 423 mg of a 1:1:0.7 mixture of 16, 17,
and [NiBr2{C10H4-1,2,3-(PPh2)3-4-{P(O)PPh2}-κP1,P2}] (18). Fur-
ther elution with acetone yielded another 520 mg of red 18.
Single crystals for X-ray analysis of 18 were obtained from a
hot mixture of chlorobenzene, toluene, and acetone. The total
NMR (200 MHz, C6D6): δ 0.90-2.20 (m, 48H), 6.85-7.20 (m,
9H), 7.20-7.40 (m, 2H), 7.70-7.85 (m, 4H). 13C{1H} NMR
(125.7 MHz, C6D6): δ 22.0 (t, J (CP) 19.5, CH2), 22.6 (t, J (CP)
19.4, CH2), 26.6 (CH2), 27.5-27.7 (m, CH2), 29.1, 29.4 (CH2),
30.0-30.2 (m, CH2), 35.1 (dd, J (CP) 16.0, 3.4, CH), 35.7 (dd,
J (CP) 16.7, 3.8, CH), 122.9 (C of PhCtC), 124.4 (CH), 127.5,
127.8, 127.9 (CH), 128.2 (d, J (CP) 7, CH), 133.9 (d, J (CP) 20.1,
CH), 141.4 (ddd, J (CP) 10.5, 5.0, 3.2, PCtC), 142.0 (dd, J (CP)
14.8, 4.0, C of PPh2), 150.3 (ddd, J (CP) 41.0, 19.0, 5.3, PCt
3
C). 31P{1H} NMR (C6D6, 81.0 MHz): δ -14.5 (dd, J (PP) 24.9,
3J (PP) 34.5, Ph2PCtCPh), 68.3 (dd, 2J (PP) 41.9, 3J (PP) 24.7),
70.1 (dd, 2J (PP) 41.9, 3J (PP) 34.6, dcpe). FAB-MS (C46H63NiP3,
tetraglyme): m/z 766 (3, M+).
X-r a y Cr ysta llogr a p h y. Crystal data, details of data
collection, data processing, structure analysis, and structure
refinement are given in Table 4.
All three structures were solved by direct methods (SIR92)47
and were expanded with use ofFourier techniques (DIRDIF94).48
The crystal structure of 11b‚3CH2Cl2 revealed a crystal-
lographic asymmetric unit comprising one clearly defined
molecule of 11b and three molecules of partly disordered CH2-

1532 Organometallics, Vol. 19, No. 8, 2000
Ta ble 4. Cr ysta l a n d Str u ctu r e Refin em en t Da ta for Com p ou n d s 11b, 18, a n d 20/21
Bennett et al.
[NiBr2{6,7-F2C10H2-1,4-Ph2-
[NiBr2{C10H4-1,2,3-(PPh2)3-
4-{P(O)PPh2}-κP1,P2}] (18)
C10H4(PPh2)2{P(O)Ph2}2
2,3-(PPh2)2-κP2,3}] (11b)
(20/21)
(a) Crystal Data
chem formula
C
46H32Br2F2NiP2‚3CH2Cl2
C58H44Br2NiOP4‚1.21C7H8‚
0.29C3H6O
C58H44O2P4‚2C2H6OS
fw
1158.01
1227.72
1053.14
cryst syst
unit cell dimens
a (Å)
b (Å)
c (Å)
monoclinic
triclinic
monoclinic
17.976(4)
28.384(9)
9.385(4)
13.431(2)
13.715(3)
16.000(2)
94.70(1)
104.06(1)
96.27(1)
2823.8(8)
P1h (No. 2)
1.444
21.296(6)
11.996(3)
23.157(7)
R (deg)
â (deg)
90.21(3)
111.18(3)
γ (deg)
V (Å3)
4789(3)
P21/a (No. 14)
1.606
5516(3)
P21/a (No. 14)
1.268
space group
Dc (g cm-3
Z
)
4
2
4
F(000)
2320
1255.56
2208
color, habit
brown-red, block
0.33 × 0.30 × 0.18
66.00 (Cu KR)
orange, plate
0.30 × 0.15 × 0.05
35.69 (Cu KR)
yellow, block
0.19 × 0.16 × 0.15
2.60 (Mo KR)
cryst dimens (mm)
µ (cm-1
)
(b) Data Collection and Processing
Rigaku AFC6R
diffractometer
X-radiation
scan mode
ω-scan width (deg)
2θ limits (deg)
data collected (h,k,l)
no. of rflns
Rigaku AFC6R
Philips PW1100/20
Cu KR (graphite monochromated) Cu KR (graphite monochromated) Mo KR (graphite monochromated)
ω-2θ
ω-2θ
ω-2θ
1.20 + 0.30 tan θ
1.20 + 0.30 tan θ
1.0 + 0.34 tan θ
120.2
120.0
40.0
(-20,0,0) to (20,31,10)
(-15,-15,-17) to (15,0,17)
(-20,0,0) to (19,11,22)
total
7822
8823
5677
unique (Rint (%))
obsd
abs cor (transmissn factors) azimuthal scans (0.23-0.31)
decay (%)
7323 (10.7)
5008 (I > 2σ(I))
8415 (5.4)
5178 (6.0)
2035 (I > 3σ(I))
none
4666 (I > 2σ(I))
azimuthal scans (0.65-0.84)
nil
nil
13
(c) Structure Analysis and Refinement
struct soln
refinement
direct methods (SIR92)
full-matrix least squares
no. of params
R(obsd data) (%)
Rw(obsd data) (%)
578
6.2
7.4
668
6.0
7.9
215
8.1
11.6
Cl2. Several of the atoms of the CH2Cl2 molecules were split
over two sites, and relative occupancies were refined. Re-
straints were placed on the C-Cl distances in these cases. The
disordered carbon atoms were refined with isotropic displace-
ment factors, while all other 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. The maximum and minimum peaks in the final differ-
ence Fourier map were 1.40 and -1.41 e/Å3, respectively, the
major features being associated with the solvent molecules.
All calculations were performed with use of teXsan structure
analysis software.49
In the crystal structure of 18‚1.21C7H8‚0.29C3H6O, the
molecular species (18) was clearly defined, but disordered
solvent molecules were also present; one series of peaks was
assigned to disordered toluene and the other to a disordered
mixture of toluene and acetone. Restraints were imposed upon
these solvent molecules and relative occupancies refined where
appropriate.50 All non-hydrogen atoms were refined anisotro-
pically by full-matrix least squares, except for those of the
disordered solvent molecules. Hydrogen atoms were included
at calculated positions (C-H ) 0.95 Å); they were not refined,
but their positions were recalculated regularly. The maximum
and minimum peaks in the final difference Fourier map were
1.22 and -0.52 e/Å3, respectively, the largest features being
associated with the bromine atoms and solvent molecules.
teXsan49 and XTAL50 software was used.
The crystal structure of 20/21‚2DMSO revealed a molecular
species with oxygen atoms bonded to P(1) and P(3) having only
partial occupancy. Data were weak, and only 2035 out of 5178
independent reflections were considered to be reliable; there-
fore, the comprehensive constrained least-squares refinement
program RAELS96 was used to minimize the number of
parameters required to describe the structure.51 Constraints
enabled 215 variables to adequately describe the refinement
of the 77 non-hydrogen atoms in the asymmetric cell.52,53 The
asymmetric unit contains a mixture of two isomers (20/21) in
a 73:27 ratio, which differ only in the location of the oxygen
atoms attached to phosphorus atoms. Atom O(2) is attached
to P(2), whereas the remaining oxygen atom is attached either
to P(1) (occupancy 0.27) or to P(3) (occupancy 0.73). Two
molecules of DMSO are also present, one of which is 0.69/0.31
disordered. The DMSO molecule was constrained to contain
an exact mirror plane, while differences in the P-O bond
(47) Altomare, A.; Cascarano, M.; Giacovazzo, C.; Guagliardi, A.;
Burla, M. C.; Polidori, G.; Camalli, M. J . Appl. Crystallogr. 1994, 27,
435.
(48) Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bosman, W. P.;
de Gelder, R.; Israel, R.; Smits, J . M. M. The DIRDIF-94 Program
System; Technical Report of the Crystallographic Laboratory; Univer-
sity of Nijmegen, Nijmegen, The Netherlands, 1994.
(49) teXsan: Single-Crystal Structure Analysis Software, Version
1.8; Molecular Structure Corp., 3200 Research Forest Drive, The
Woodlands, TX 77381, 1997.
(51) Rae, A. D. RAELS96: A Comprehensive Constrained Least-
Square Refinement Program; Australian National University, Can-
berra, ACT, Australia, 1996.
(52) Rae, A. D. Acta Crystallogr. 1975, A31, 560.
(53) Rae, A. D. Acta Crystallogr. 1984, A40 Supplement, C428.
(50) Hall, S. R., King, G. S. D., Steward, J . M., Eds. XTAL3.4
Reference Manual; University of Western Australia, Lamb: Perth,
Australia, 1995.

Insertion of Phosphines into Ni(0) Benzyne Complexes
Organometallics, Vol. 19, No. 8, 2000 1533
lengths were constrained to approach zero. All atoms were
described by refinable rigid body thermal parametrizations.52
The hydrogen atoms were relocated in sensible chemical
positions after each refinement cycle. The maximum and
minimum peaks in the final difference Fourier map were 1.0
and -1.3 e/Å3, respectively. Calculations were performed with
the crystallographic software packages teXsan,49 XTAL,50 and
RAELS96.51
∆f ′ and ∆f′′ values and mass attenuation coefficients were
taken from ref 55 for all three structures.
Ack n ow led gm en t. C.J .C. gratefully acknowledges
the receipt of a Fellowship from the Royal Society of
London, and E.W. thanks the Australian Research
Council for a QEII Research Fellowship.
The neutral atom scattering factors were taken from ref 54
for structure 11b and from ref 55 for structures 18 and 20/21.
Su p p or tin g In for m a tion Ava ila ble: Figures giving ad-
ditional views and tables giving X-ray crystallographic data
for 11b‚3CH2Cl2, 18‚1.21C7H8‚0.29C3H6O, and 20/21‚2DMSO.
This material is available free of charge via the Internet at
http://pubs.acs.org.
(54) Cromer, D. T.; Waber, J . T. International Tables for X-ray
Crystallography; Kynoch Press: Birmingham, England, 1974; Vol. IV.
(55) International Tables for Crystallography; Wilson, A. J . C., Ed.;
Kluwer Academic: Dordrecht, The Netherlands, 1992; Vol. C.
OM990749M