Synthesis of phosphine tethered η2-allene and μ-η1:η2-alkenyl complexes: Facile P-Cα bond formation and C-H activation reactions of bis(diphenylphosphino)methane with [Fe2(CO)6(μ-ER){μ-η1:η

Article abstract of DOI:10.1021/om960502e

The phosphido-bridged diiron allenyl complex [Fe₂(CO)₆(μ-PPh₂){μi-η ¹:η_αβ²-(H)C _α=C_β=C_γH₂}] (1) reacts with dppm to afford, in the first instance, [Fe₂(CO)₆(μ-PPh₂){η ¹(P):η²(C)-Ph₂PCH₂-PPh ₂(H)C=C=CH₂}] (3), which contains a novel η¹(P):η²(C)-dppm-functionalized allene. A single-crystal X-ray study reveals 3 to be derived from 1 by nucleophilic attack of dppm at C_α with metal-metal bond cleavage and internuclear migration of CO. Upon standing in toluene [Fe₂(CO)₆(μ-PPh₂){η ¹(P):η²(C)-Ph₂PCH₂PPh ₂(H)C=C=CH₂}] (3) slowly decarbonylates to afford the unusual σ-π-alkenyl complex [Fe₂(CO)₅(μ-PPh₂){μ-η ¹(P):η¹(C):η²(C)-Ph ₂PCHPPh₂-(H)C=CCH₃}] (4), containing a metal- and carbon-coordinated bis(diphenylphosphino)-methanide ligand. Overall, the transformation of 3 into 4 requires activation of a dppm methylene C-H bond, hydrogen migration to C_γ together with metal - metal bond formation, and loss of CO. Surprisingly, [Fe₂(CO)₆(μ;-S^tBu){μ-η ¹:η_α,β²-(H)C _α=C_β=C_γH₂}] and dppm react to afford high yields of the isomeric alkenyl complexes [Fe₂(CO)₅(μ-S^tBu){μ-η ¹(P):η¹(C):η²(C)-Ph ₂PCHPPh₂(H)C=CCH₃}] (5a; 90percent) and [Fe₂(CO)₅(μ-S^tBu){μ-η ¹(P):η¹(C):η²(C)-Ph ₂PCHPPh₂-CH₂C=CH₂}] (5b; 10percent), the former of which is a structural analogue of [Fe₂(CO)₅(μ-PPh₂){μ-η ¹(P):η¹(C):η²(C)-Ph ₂PCHPPh₂(H)C=CCH₃}] (4). We tentatively suggest that 5a and 5b form via C-H activation and hydrogen migration in an η²-allene intermediate similar to 3 with the final isomeric distribution depending upon the regiochemistry of the hydrogen migration step, namely to C_α or C_γ. Full structural details of 3, 4, 5a, and 5b are reported.

Full text of DOI:10.1021/om960502e

5302
Organometallics 1996, 15, 5302-5308
Syn th esis of “P h osp h in e Teth er ed ” η2-Allen e a n d
µ-η1:η2-Alk en yl Com p lexes: F a cile P -Cr Bon d F or m a tion
a n d C-H Activa tion Rea ction s of
Bis(d ip h en ylp h osp h in o)m eth a n e w ith
[F e2(CO)6(µ-ER){µ-η1:η2r,â-(H)CrdCâdCγH2}] (E ) P P h , R )
t
P h ; E ) S, R ) Bu )
Simon Doherty,*,† Mark R. J . Elsegood, William Clegg, Dirk Mampe, and
Nicholas H. Rees
Department of Chemistry, Bedson Building, The University of Newcastle upon Tyne,
Newcastle upon Tyne NE1 7RU, United Kingdom
Received J une 21, 1996X
The phosphido-bridged diiron allenyl complex [Fe2(CO)6(µ-PPh2){µ-η1:η2R,â-(H)CRdCâdCγH2}]
(1) reacts with dppm to afford, in the first instance, [Fe2(CO)6(µ-PPh2){η1(P):η2(C)-Ph2PCH2-
PPh2(H)CdCdCH2}] (3), which contains a novel η1(P):η2(C)-dppm-functionalized allene. A
single-crystal X-ray study reveals 3 to be derived from 1 by nucleophilic attack of dppm at
CR with metal-metal bond cleavage and internuclear migration of CO. Upon standing in
toluene [Fe2(CO)6(µ-PPh2){η1(P):η2(C)-Ph2PCH2PPh2(H)CdCdCH2}] (3) slowly decarbonylates
to afford the unusual σ-π-alkenyl complex [Fe2(CO)5(µ-PPh2){µ-η1(P):η1(C):η2(C)-Ph2PCHPPh2-
(H)CdCCH3}] (4), containing a metal- and carbon-coordinated bis(diphenylphosphino)-
methanide ligand. Overall, the transformation of 3 into 4 requires activation of a dppm
methylene C-H bond, hydrogen migration to Cγ together with metal-metal bond formation,
and loss of CO. Surprisingly, [Fe2(CO)6(µ-StBu){µ-η1:η2R,â-(H)CRdCâdCγH2}] and dppm react
to afford high yields of the isomeric alkenyl complexes [Fe2(CO)5(µ-StBu){µ-η1(P):η1(C):η2(C)-
Ph2PCHPPh2(H)CdCCH3}] (5a ; 90%) and [Fe2(CO)5(µ-StBu){µ-η1(P):η1(C):η2(C)-Ph2PCHPPh2-
CH2CdCH2}] (5b; 10%), the former of which is a structural analogue of [Fe2(CO)5(µ-PPh2){µ-
η1(P):η1(C):η2(C)-Ph2PCHPPh2(H)CdCCH3}] (4). We tentatively suggest that 5a and 5b form
via CsH activation and hydrogen migration in an η2-allene intermediate similar to 3 with
the final isomeric distribution depending upon the regiochemistry of the hydrogen migration
step, namely to CR or Cγ. Full structural details of 3, 4, 5a , and 5b are reported.
In tr od u ction
a dppm at a µ-η1:η1-coordinated alkyne.6 Although there
have been relatively few reports of nucleophilic attack
between bidentate phosphines and unsaturated hydro-
carbyl ligands,4-6 P-C bond formation involving mono-
functional phosphines is well-documented.7
By far the most common role for bis(diphenylphos-
phino)methane (dppm) is that of a bridging ligand, and
as such it has found widespread use as a versatile
supporting ligand in an impressive array of complexes.1
However, a growing number of reports suggest that
dppm has a rich and varied chemistry far beyond that
of an innocent spectator ligand. Indeed, recent years
have witnessed some quite remarkable observations,
including facile P-C bond cleavage reactions,2 metala-
tion of the aromatic C-H bonds,3 competitive nucleo-
philic attack between carbon and metal atoms in
binuclear hydrocarbyl-bridged complexes,4,5 and re-
cently, intramolecular nucleophilic attack of one end of
We have recently initiated a systematic investigation
into the reactivity of the diiron allenyl complexes [Fe2-
(CO)6(µ-ER){µ-η1:η2R,â-(H)CRdCâdCγH2}] (E ) PPh, R
) Ph, 1; E ) S, R ) tBu, 2), and our efforts in this area
have unveiled a wealth of unexpected reactivity toward
monofunctional nucleophiles, including the generation
of amido-functionalized alkenyl complexes via a novel
amine-carbonyl-allenyl coupling sequence8 and an
unprecedented nucleophilic attack of primary and sec-
ondary phosphines at CR to afford, after 1,4-hydrogen
migration, new phosphino-substituted µ-η1:η2-alkenyl
ligands.9 In addition to these studies we are currently
examining the reactivity of 1 and 2 with dppm to
compare with [Ru2(CO)6(µ-PPh2){µ-η1:η2-(Ph)CRdCâd
CγH2}], which was reported to react via allenyl-carbo-
nyl-phosphido coupling to afford a novel ketoallenyl
† E-mail: simon.doherty@newcastle.ac.uk.
X Abstract published in Advance ACS Abstracts, November 15, 1996.
(1) (a) Puddephatt, R. J . Chem. Soc. Rev. 1983, 12, 99. (b) Chaudret,
B.; Delavaux, B.; Poiblanc, R. Coord. Chem. Rev. 1988, 86, 191.
(2) (a) Hogarth, G.; Knox, S. A. R.; Turner, M. L. J . Chem. Soc.,
Chem. Commun. 1990, 145. (b) Hogarth, G.; Knox, S. A. R.; MacPher-
son, K. A.; Melchior, F.; Morton, D. A. V.; Orpen, A. G. Inorg. Chim.
Acta 1992, 198-200, 257. (c) Hogarth, G.; Knox, S. A. R.; Turner, M.
L. J . Chem. Soc., Chem. Commun. 1990, 145.
(3) Doherty, N. M.; Hogarth, G.; Knox, S. A. R.; Macpherson, K. A.;
Melchior, F.; Orpen, A. G. J . Chem. Soc., Chem. Commun. 1986, 540.
(4) Hogarth, G.; Knox, S. A. R.; Lloyd, B. R. L.; Macpherson, K. A.;
Melchior, F.; Morton, D. A. V.; Orpen, A. G. J . Chem. Soc., Chem.
Commun. 1988, 360.
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L. H.; Breckenridge, S. M.; Taylor, N. J .; Carty, A. J . Organometallics
1992, 11, 1701.
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S0276-7333(96)00502-X CCC: $12.00 © 1996 American Chemical Society

“Phosphine Tethered” Allene and Alkenyl Complexes
Organometallics, Vol. 15, No. 25, 1996 5303
phosphine.10 Herein we describe a new reaction path-
way for bis(diphenylphosphino)methane with σ-η-allenyl
complexes, which involves PsCR bond formation to-
gether with activation of a dppm methylene CsH bond,
and hydrogen migration to the coordinated allenyl
ligand. Both 1 and 2 react with dppm to ultimately
afford the bis(diphenylphosphino)methanide-tethered
µ-η1:η2-alkenyl complexes [Fe2(CO)5(µ-ER){µ-η1(P):η1(C):
η2(C)-Ph2PCHPPh2(H)CdCCH3}] (4, E ) PPh, R ) Ph;
5a , E ) S, R ) tBu) and [Fe2(CO)5(µ-ER){µ-η1(P):η1(C):
t
η2(C)-Ph2PCHPPh2CH2CdCH2}] (5b, E ) S, R ) Bu),
although in the case of [Fe2(CO)6(µ-PPh2){µ-η1:η2R,â-(H)-
CRdCâdCγH2}] (1) nucleophilic attack at CR of the
allenyl ligand initially affords the intermediate [Fe2-
(CO)6(µ-PPh2){η1(P):η2(C)-Ph2PCH2PPh2(H)CdCd-
CH2}] (3), which contains an η1(P):η2(C)-coordinated
dppm-functionalized allene. The bis(diphenylphosphi-
no)methanide anion, formally derived from dppm by
deprotonation, is increasing in popularity as a coordi-
natively and electronically versatile ligand for transition
metals in a variety of oxidation states, and such
complexes are generally accessed via metathesis routes11
or deprotonation of a coordinated dppm.12 The genera-
tion of 4, 5a , and 5b represents, to the best of our
knowledge, the first examples of a facile CsH bond
activation-hydrogen migration pathway during the
reaction of dppm with a σ-η-hydrocarbyl complex.
F igu r e 1. Molecular structure of [Fe2(CO)6(µ-PPh2){η1(P):
η2(C)-Ph2PCH2PPh2(H)CdCdCH2}] (3), illustrating the η1-
(P):η2(C) “phosphine tethered” allene ligand. Phenyl hy-
drogen atoms have been omitted. Ellipsoids are at the 50%
probability level.
Resu lts a n d Discu ssion
R ea ct ion of [F e2(CO)6(µ-P P h 2){µ-η1:η2r,â-(H )-
CrdCâdCγH2}] w ith d p p m : Syn th esis a n d Ch a r -
a cter iza tion of [F e2(CO)5(µ-P P h 2){µ-η1(P ):η1(C):η2-
(C)-P h 2P CHP P h 2(H)CdCCH3}] (3) a n d [F e2(CO)5(µ-
P P h 2 ) {µ-η1 ( P ) :η1 ( C ) :η2 ( C ) -P h 2 P C H P P h
-
2
CH2CdCH2}] (4). The diiron allenyl complex [Fe2-
(CO)6(µ-PPh2){µ-η1:η2R,â-(H)CRdCâdCγH2}] (1) reacts
with dppm, in toluene/diethyl ether, to afford [Fe2(CO)6-
(µ-PPh2){η1(P):η2(C)-Ph2PCH2PPh2(H)CdCdCH2}] (3),
which crystallizes directly from the reaction mixture in
yields of up to 60%. As expected, the 31P{1H} NMR
spectrum of 3 contains three distinct mutually coupled
resonances (δ 75.6, 73.7, 37.8 ppm (ABX)). Of these,
the two at low field are associated with the bridging
phosphido ligand and the metal-coordinated diphos-
phine, the former of which appears in the region most
commonly associated with µ-PPh2 bridging nonbonded
metal atoms.13 The remaining high-field signal is
characteristic of a carbon-coordinated diphosphine.5 All
three 13C signals associated with the C3-bridging ligand
have been identified, two of which have chemical shifts
close to those of Câ and Cγ in 19 (3, δ 176.5, 119.0; 1, δ
180.0, 79.0 ppm), while the remaining signal, that
associated with CR, is shifted to high field (3, δ 18.4 ppm,
1J PC ) 76.0 Hz; 1, δ 118.3 ppm). These spectroscopic
features suggest that the reaction of 1 with dppm occurs
with PsC bond formation, retention of the uncoordi-
nated CsC double bond, and metal-metal bond cleav-
age. However, beyond this, the exact nature of 3
remained uncertain and a single-crystal X-ray study
was undertaken to provide full structural details.
The results of the structural study are presented in
Figure 1 with a selection of bond distances and angles
listed in Table 1. The most remarkable feature of this
structure is the transformation of a µ-η1:η2-allenyl
ligand into a η1(P):η2(C)-coordinated dppm-functional-
ized allene (C(1)-P(3) ) 1.753(6) Å, Fe(1)-C(1) ) 2.030-
(6) Å, Fe(1)-C(2) ) 1.942(6) Å). Overall, formation of
3 requires P-CR bond formation, cleavage of the Fe-
Fe bond, redistribution of the carbonyl ligands, and η2-
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Organomet. Chem. 1984, 265, 87. For vinylidenes: (k) Bruce, M. I.
Chem. Rev. 1991, 91, 197. For carbenes and carbynes: (l) Kreissl, F.
R.; Hel, W. Chem. Ber. 1977, 110, 799. (m) Fischer, E. O.; Reitmeier,
R.; Ackermann, K. Angew. Chem., Int. Ed. Engl. 1983, 22, 411. (n)
Kreissl, F. R.; Friedrich, P. Angew. Chem., Int. Ed. Engl. 1977, 16,
543. (o) Kreissl, F. R.; Stuckler, P.; Meineke, E. W. Chem. Ber. 1977,
110, 3040. (p) Fischer, E. O.; Ruhs, A.; Kreissl, F. R. Chem. Ber. 1977,
110, 805. (q) Busetto, L.; Carlucci, L.; Zanotti, V.; Albano, V. G.; Monari,
M. Chem. Ber. 1992, 125, 1125. (r) Bassi, M.; Carlucci, L.; Zanotti, V.
Inorg. Chim. Acta 1993, 204, 171. For allenyl and propargyl com-
plexes: (s) Casey, C. P.; Yi, C.-S. J . Am. Chem. Soc. 1992, 114, 6597.
(t) Henrick, K.; McPartlin, M.; Deeming, A. J .; Hasso, S.; Manning, P.
J . Chem. Soc., Dalton Trans. 1982, 899. (u) Breckenridge, S. M.; Taylor,
N. J .; Carty, A. J . Organometallics 1991, 10, 837.
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metallics 1996, 15, 2688.
(9) Doherty, S.; Elsegood, M. R. J .; Clegg, W.; Scanlan, T.; Rees, N.
H. J . Chem. Soc. Chem. Commun. 1996, 1545.
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Taylor, N. J .; Carty, A. J . Organometallics 1994, 13, 4179.
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5304 Organometallics, Vol. 15, No. 25, 1996
Doherty et al.
Ta ble 1. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for Com p ou n d 3
Fe(1)-C(1)
Fe(1)-P(1)
P(2)-C(34)
P(3)-C(34)
C(2)-C(3)
2.030(6)
2.356(2)
1.853(6)
1.801(6)
1.305(9)
Fe(1)-C(2)
Fe(1)-P(2)
C(1)-P(3)
C(1)-C(2)
1.942(6)
2.218(2)
1.753(6)
1.445(9)
Fe(2)-P(1)-Fe(1)
P(2)-Fe(1)-P(1)
P(3)-C(34)-P(2)
P(3)-C(1)-Fe(1)
C(2)-C(1)-P(3)
121.70(7)
175.37(7)
108.8(3)
114.7(3)
117.5(5)
C(3)-C(2)-C(1)
C(34)-P(2)-Fe(1)
C(1)-P(3)-C(34)
C(1)-Fe(1)-P(2)
137.4(6)
108.7(2)
106.2(3)
90.0(2)
coordination of the allene ligand. Atoms Fe(1), P(2),
C(34), P(3), and C(1) form a five-membered saturated
ring system and, since P(3) is attached to four carbon
atoms, it is zwitterionic with the negative charge
delocalized onto the iron atoms. The C(1)-C(2) bond
length (1.445(9) Å) shows the expected increase upon
coordination and is comparable to values in other allene
complexes.14 The dihedral angle of 89.8° between the
planes defined by P(3), C(1), H(1) and H(3a), C(3), H(3b)
reflects the allenic character of this modified hydrocar-
byl fragment (all these hydrogens were freely refined),
although there is a significant deviation of C(1)C(2)C-
(3) from linearity (137.4(6)°). This, we believe, is the
first example of PsC bond formation between a µ-η1:
η2-allenyl ligand and a diphosphine; in fact, PsC bond
formation between dppm and σ-η-hydrocarbyl ligands
is not a common reaction pathway. Two such com-
plexes, [Fe2(CO)6{µ-C(CH2)P(Ph2)CH2PPh2}]4 and [Fe2-
(CO)5(µ-PPh2){µ-CdC(Ph)Ph2PCH2PPh2}],5 have been
structurally characterized, both of which contain a
carbon- and metal-bonded diphosphine, although ther-
molysis of the latter in toluene readily leads to PsC
bond cleavage, elimination of CO, and formation of the
disubstituted complex [Fe2(CO)4(µ-PPh2)(µ-dppm)(µ-η1:
η2-CdCPh)]. We have found complex 2 to be stable with
respect to PsC bond cleavage, and our efforts to
transform it into [Fe2(CO)4(µ-PPh2)(µ-dppm){µ-η1:η2-(H)-
CRdCâdCγH2}] by heating a toluene solution at 80 °C
overnight have proven unsuccessful.
F igu r e 2. Molecular structure of [Fe2(CO)5(µ-PPh2){µ-
η1(P):η1(C):η2(C)-Ph2PC(H)PPh2(H)CdCCH3}] (4), high-
lighting the bis(diphenylphosphino)methanide-functional-
ized σ-π-alkenyl ligand. Phenyl hydrogens have been
omitted.
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for Com p ou n d 4
Fe(1)-Fe(2)
Fe(1)-C(3)
Fe(1)-P(1)
Fe(2)-P(3)
P(2)-C(21)
C(1)-C(2)
2.6050(12)
2.099(6)
2.2683(17)
2.2169(19)
1.696(6)
Fe(1)-C(2)
Fe(2)-C(2)
Fe(1)-P(3)
P(1)-C(21)
C(3)-P(2)
C(2)-C(3)
2.075(6)
2.002(6)
2.2263(17)
1.723(6)
1.789(6)
1.431(8)
1.497(8)
Fe(2)-P(3)-Fe(1)
71.79(6)
C(21)-P(1)-Fe(1) 108.2(2)
P(3)-Fe(1)-P(1) 167.62(7)
P(2)-C(21)-P(1) 116.4(3)
P(2)-C(3)-Fe(1) 114.0(3)
C(21)-P(2)-C(3)
C(3)-Fe(1)-P(1)
C(3)-Fe(1)-P(3)
107.9(3)
87.39(17) C(3)-C(2)-C(1)
83.31(17)
119.8(5)
dppm and allenyl methylene groups in 4, supported by
DEPT and 13C{1H}-1H correlated NMR experiments,
prompted us to undertake a single-crystal X-ray study
in order to reveal the precise nature of this transforma-
tion.
A perspective view of the molecular structure together
with the atomic numbering scheme is illustrated in
Figure 2 with a selection of bond distances and angles
listed in Table 2. First and foremost we note the
presence of a metal- and carbon-bonded dppm in 4 (Fe-
(1)-P(1) ) 2.2683(17) Å, P(2)-C(3) ) 1.789(6) Å) and a
µ-PPh2 bridging a metal-metal bond (Fe(1)-Fe(2) )
2.6050(12) Å), structural characteristics that readily
account for the 31P{1H} NMR data. The most remark-
able feature of this structure is the transformation of a
η1(P):η2(C)-dppm-functionalized allene into a bis(diphen-
ylphosphino)methanide-tethered µ-η1:η2-alkenyl group
σ-bonded to Fe(2) (Fe(2)-C(2) ) 2.002(6) Å) and π-bond-
ed to Fe(1) (Fe(1)-C(2) ) 2.075(6) Å, Fe(1)-C(3) )
2.099(6) Å). The alkenyl ligand in 4 adopts an endo
conformation with respect to the phosphido bridge15 and
is tethered to Fe(1) by coordination of the bis(diphen-
ylphosphino)methanide. Atoms P(2), C(21), P(1), Fe-
(1), and C(3) form a partially unsaturated five-mem-
bered ring comprising the bis(diphenylphosphino)-
methanide fragment, Câ of the σ-π-alkenyl ligand (for-
mally CR of the allenyl ligand), and Fe(1) (Scheme 1).
The bis(diphenylphosphino)methanide shows the ex-
pected contraction in P-C bond length (P(1)-C(21) )
1.723(6) Å, P(2)-C(21) ) 1.696(6) Å) due to partial
Surprisingly, upon standing, toluene solutions of 3
smoothly decarbonylate to form [Fe2(CO)5(µ-PPh2){µ-
η1(P):η1(C):η2(C)-Ph2PCHPPh2(H)CdCCH3}] (4), readily
identified by the appearance of a new set of resonances
in the 31P{1H} NMR spectrum of the reaction mixture.
One of these, a low-field doublet of doublets (δ 185.5,
2J PP ) 63.0, 39.0 Hz), appears in the region commonly
encountered for µ-PPh2 ligands bridging metal-metal
bonds.13 The remaining two sets of resonances, both
doublets of doublets, are relatively unshifted, which
suggests little or no change in the mode of coordination
of dppm, although the phosphorus-phosphorus coupling
constant of 122.0 Hz is substantially larger than in 3.
In addition, the 13C{1H} NMR spectrum of 4 provides
further support for retention of the metal-carbon
coordinated dppm in the form of a low-field resonance
(δ 57.7 ppm) with a relatively large phosphorus-carbon
coupling constant (1J PC ) 75.0 Hz). The 13C{1H} NMR
spectrum of 4 also contains an unusually high field
shifted doublet of doublets at δ 7.8 with exceptionally
large phosphorus-carbon coupling constants (1J PC
)
133.4, 63.7 Hz). Finally, the apparent absence of both
(14) Barry, J . T.; Chacon, S. T.; Chisholm, M. H.; Huffman, J . C.;
Streib, W. J . Am. Chem. Soc. 1995, 117, 1974.
(15) MacLaughlin, S. A.; Doherty, S.; Taylor, N. J . Carty, A. J .
Organometallics 1992, 11, 4315.

“Phosphine Tethered” Allene and Alkenyl Complexes
Organometallics, Vol. 15, No. 25, 1996 5305
Sch em e 1
multiple-bond character within the PCP framework.11,12
Overall, the transformation of 3 into 4 involves activa-
tion of a dppm methylene C-H bond together with a
1,5-hydrogen migration to Cγ (C(1)), re-formation of the
metal-metal bond, and elimination of carbon monoxide.
Rea ction of [F e2(CO)6(µ-St Bu ){µ-η1:η2r,â-(H)Crd
CâdCγH2}] w ith d p p m : Syn th esis a n d X-r a y Str u c-
t u r es of [F e2(CO)5(µ-St Bu ){µ-η1(P ):η1(C):η2(C)-
P h 2P CHP P h 2(H)CdCCH3}] (5a ) a n d [F e2(CO)5(µ-
S t B u ) {µ-η1 ( P ) :η1 ( C ) :η2 ( C ) -P h 2 P C H P P h
-
2
CH2CdCH2}] (5b). Our efforts to extend this chemis-
try to the sulfido-bridged complex [Fe2(CO)6(µ-StBu){µ-
η1:η2-(H)CRdCâdCγH2}] (2) resulted in the unexpected
isolation of the isomeric bis(diphenylphosphino)-
methanide-functionalized µ-η1:η2-alkenyl complexes
[Fe2(CO)5(µ-St Bu){µ-η1(P):η1(C):η2(C)-Ph2PCHPPh2-
(H)CdCCH3}] (5a ) and [Fe2(CO)5(µ-StBu){µ-η1(P):η1(C):
η2(C)-Ph2PCHPPh2CH2CdCH2}] (5b). Treatment of a
diethyl ether solution of 2 with dppm at 298 K resulted
in the instantaneous formation of a deep red solution.
Removal of the solvent, extraction into hexane, and
crystallization at 0 °C yielded X-ray-quality crystals of
deep red [Fe2(CO)5(µ-StBu){µ-η1(P):η1(C):η2(C)-Ph2-
PCHPPh2(H)CdCCH3}] (5a ; 90%) and orange [Fe2-
(CO)5 (µ-St Bu ){µ-η1 (P ):η1 (C):η2 (C)-P h 2 P CH P P h 2 -
CH2CdCH2}] (5b; 10%). The 31P{1H} characteristics of
F igu r e 3. Molecular structure of [Fe2(CO)5(µ-StBu){µ-
η1(P):η1(C):η2(C)-Ph2PC(H)PPh2(H)CdCCH3}] (5a , molecule
A), illustrating the five-membered-ring system formed by
iron and carbon coordination of dppm. Phenyl and tert-
butyl hydrogens have been omitted.
Ta ble 3. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for Com p ou n d 5a
molecule A
molecule B
2
Fe(1)-Fe(2) 2.548(2)
Fe(3)-Fe(4)
2.572(2)
2.088(12)
2.101(12)
1.969(12)
2.240(3)
2.283(3)
2.262(4)
1.756(12)
1.638(13)
1.805(12)
1.507(17)
1.446(18)
5a and 5b (5a , 61.8, 25.9 ppm, J PP ) 112.0 Hz; 5b,
Fe(1)-C(2)
Fe(1)-C(3)
Fe(2)-C(2)
Fe(1)-P(2)
Fe(1)-S(1)
Fe(2)-S(1)
P(2)-C(16)
P(1)-C(16)
C(3)-P(1)
C(1)-C(2)
C(2)-C(3)
2.072(11) Fe(3)-C(39)
2.106(11) Fe(3)-C(40)
2.017(12) Fe(4)-C(39)
2.249(3)
2.273(3)
2.257(3)
1.730(14) P(4)-C(53)
1.661(13) P(3)-C(53)
1.786(12) C(40)-P(3)
1.491(16) C(38)-C(39)
1.427(16) C(39)-C(40)
2
60.6, 30.4 ppm, J PP ) 72.0 Hz) leave little doubt that
both complexes contain a metal- and carbon-coordinated
bis(diphenylphosphino)methanide. Moreover, the 13C-
{1H} NMR spectrum of 5a contained a high-field-shifted
doublet of doublets at δ 8.6 with coupling constants
similar in magnitude to those previously reported for
this ligand type.11,12 Unfortunately, the low isolated
yields of 5b prevented us from obtaining its 13C{1H}
NMR spectrum, and on the basis of 1H NMR data alone
we were unable to arrive at a reasonable formulation.
However, the precise identity of both 5a and 5b were
finally underpinned with single-crystal X-ray studies.
A single-crystal X-ray study of 5a was undertaken to
compare with that of 4. Compound 5a crystallizes with
two independent but essentially identical molecules in
the asymmetric unit of the monoclinic cell, and the
following discussion is based on data for molecule A. A
perspective view of the molecular structure of 5a is
presented in Figure 3, while Table 3 lists a selection of
bond distances and angles for both molecules A and B.
The molecular structure identifies 5a as [Fe2(CO)5(µ-
Fe(3)-P(4)
Fe(3)-S(2)
Fe(4)-S(2)
Fe(2)-S(1)-Fe(1) 68.46(10) Fe(4)-S(2)-Fe(3)
P(2)-Fe(1)-S(1) 165.98(14) P(4)-Fe(3)-S(2)
68.92(10)
165.77(14)
111.5(6)
108.1(6)
117.7(7)
105.5(4)
88.2(3)
P(1)-C(3)-Fe(1) 112.2(5)
C(16)-P(1)-C(3) 107.7(6)
P(1)-C(16)-P(2) 117.8(7)
C(16)-P(2)-Fe(1) 105.5(4)
C(3)-Fe(1)-P(2) 87.5(3)
P(3)-C(40)-Fe(3)
C(53)-P(3)-C(40)
P(3)-C(53)-P(4)
C(53)-P(4)-Fe(3)
C(40)-Fe(3)-P(4)
C(1)-C(2)-C(3)
119.0(10) C(38)-C(39)-C(40) 117.2(11)
StBu){µ-η1(P):η1(C):η2(C)-Ph2PCHPPh2(H)CdCCH3}], for
which the principal feature of interest is the bis-
(diphenylphosphino)methanide-functionalized µ-η1:η2-

5306 Organometallics, Vol. 15, No. 25, 1996
Doherty et al.
between 5a and 5b lies in the isomeric µ-η1: η2-alkenyl
ligands, whose coordination isomerism manifests itself
in the formation of the five- and six-membered rings of
5a and 5b, respectively. At this time we tentatively
suggest the selectivity for 5a to be electronic in origin
(η2-coordination to a phosphine-substituted iron), to-
gether with a contribution from the inherent stability
of five-membered rings. The remainder of the structure
is as expected for a diiron sulfido-bridged σ-π-alkenyl
complex. We suggest that 5a and 5b form via CsH
activation and hydrogen migration in an η2-allene
intermediate similar to 3, the final isomeric distribution
depending upon the regiochemistry of hydrogen migra-
tion (Scheme 1).
The regioselective attack of neutral phosphorus-based
nucleophiles at CR of the µ-η1:η2-allenyl ligand in [Fe2-
(CO)6(µ-PPh2){µ-η1:η2R,â-(H)CRdCâdCγH2}] (1) contrasts
sharply with previous reports of exclusive attack of
carbon, phosphorus, and nitrogen nucleophiles at Câ of
binuclear µ-η1:η2- and mononuclear η3-allenyl com-
plexes.7u,16 For instance, in all cases [Ru2(CO)6(µ-PPh2)-
{µ-η1:η2R,â-(Ph)CRdCâdCγH2}] reacts with monofunc-
tional nucleophiles to form dimetallacyclopentanes and
pentenes via attack at Câ.7u However, EHMO calcula-
tions on the model compound [Ru2(CO)6(µ-PH2){µ-η1:
η2R,â-(H)CRdCâdCγH2}] have shown that a significant
component of the lowest unoccupied molecular orbital
(LUMO) is centered on CR and the lack of reactivity at
this carbon was suggested to be steric in origin. The
selectivity of [Ru2(CO)6(µ-PPh2){µ-η1:η2R,â-(Ph)CRd
CâdCγH2}] for nucleophilic attack at Câ was eventually
rationalized by examining the characteristics of the
LUMO and HOMO during rotation about Câ-Cγ, a
dynamic process thought to be responsible for the
exchange of the methylene protons. These studies
showed that the orbital contribution to the LUMO from
Câ maximizes at a rotation of the CγH2 fragment of 88°
with respect to the CH2 plane in the ground state.
Moreover, during this rotation a positive charge also
F igu r e 4. Molecular structure of [Fe2(CO)5(µ-StBu){µ-
η1(P):η1(C):η2(C)-Ph2PCHPPh2CH2CdCH2}] (5b), highlight-
ing the six-membered ring formed by the “phosphine
tethered” µ-η1(P):η1(C):η2(C)-coordinated alkenyl ligand.
Phenyl and tert-butyl hydrogen atoms have been omitted.
Ta ble 4. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for Com p ou n d 5b
Fe(1)-Fe(2)
Fe(1)-C(2)
Fe(1)-S(1)
Fe(2)-P(2)
C(21)-P(1)
C(1)-C(2)
2.5439(6)
2.111(3)
2.3061(8)
2.2082(9)
1.682(3)
1.400(4)
Fe(1)-C(1)
Fe(2)-C(2)
Fe(2)-S(1)
P(2)-C(21)
C(3)-P(1)
C(2)-C(3)
2.157(3)
1.987(3)
2.2589(8)
1.744(3)
1.823(3)
1.513(4)
Fe(2)-S(1)-Fe(1)
67.72(2)
P(2)-Fe(2)-S(1) 106.95(3)
C(21)-P(2)-Fe(2) 116.75(10) P(1)-C(21)-P(2) 127.94(17)
C(21)-P(1)-C(3)
C(3)-C(2)-Fe(2)
C(1)-C(2)-C(3)
110.12(14) C(2)-C(3)-P(1)
120.13(19) C(2)-Fe(2)-P(2)
113.8(2)
107.38(19)
86.24(8)
alkenyl ligand, σ-bonded to Fe(2) (Fe(2)-C(2) ) 2.017-
(12) Å) and π-bonded to Fe(1) (Fe(1)-C(2) ) 2.072(11)
Å, Fe(1)-C(3) ) 2.106(11) Å). Complex 5a , a structural
analogue of 4, is derived from 2 via P-CR bond forma-
tion, activation of a dppm methylene C-H bond coupled
with hydrogen transfer to Cγ, and coordination of the
remaining phosphorus to Fe(1) to generate a partially
unsaturated five-membered ring. The phosphorus-
carbon bonds of the bis(diphenylphosphino)methanide
fragment in 5a (P(1)-C(16) ) 1.661(13) Å, P(2)-C(16)
) 1.730(14) Å) are considerably shorter than the cor-
responding ones in 3 and similar to those in 4, consistent
with a degree of multiple bonding in the P-C-P
fragment. A number of transition-metal bis(diphen-
ylphosphino)methanide complexes have been crystallo-
graphically characterized, and in each case similar bond
length reductions have been noted compared with their
neutral dppm counterparts.11,12A single-crystal X-ray
analysis identified 5b as [Fe2(CO)5(µ-StBu){µ-η1(P):
η1(C):η2(C)-Ph2PCHPPh2CH2CdCH2}], an isomer of 5a
by virtue of competitive 1,3-hydrogen migration to CR
of the µ-η1:η2-allenyl in 2. In addition, 5a and 5b also
exhibit coordination isomerism in that the σ-π-alkenyl
ligand of 5b is η2-coordinated to the unsubstituted Fe-
(CO)3 fragment (Fe(1)-C(2) ) 2.111(3) Å, Fe(1)-C(1)
) 2.157(3) Å), while in 5a this ligand is η2-coordinated
to the phosphine-tethered iron (Scheme 1). Atoms P(1),
C(3), C(2), Fe(2), P(2), and C(21) form a six-membered-
ring system containing the bis(diphenylphosphino)-
methanide (P(2)-C(21) ) 1.744(3) Å, P(1)-C(21) )
1.682(3) Å) whose PsC bonds are comparable in length
to those of 4 and 5a . The most notable difference
develops on Câ
, which suggests that overall the reactiv-
ity of [Ru2(CO)6(µ-PPh2){µ-η1:η2R,â-(Ph)CRdCâdCγH2}]
toward neutral nucleophiles is controlled by both orbital
and charge factors. The highly regioselective attack of
phosphorus-based nucleophiles at CR of the µ-η1:η2
-
R,â
allenyl ligand in 1 prompted us to perform preliminary
EHMO calculations17 on the model compound [Fe2(CO)6-
(µ-PH2){µ-η1:η2R,â-(H)CRdCâdCγH2}] using parameters
derived from the X-ray structure of [Fe2(CO)6(µ-PPh2)-
{µ-η1:η2R,â-(H)CRdCâdCγH2}].18 These calculations re-
veal that in the ground state, as for [Ru2(CO)6(µ-
PPh2){µ-η1:η2R,â-(Ph)CRdCâdCγH2}], the LUMO has a
(16) For comprehensive reviews on transition-metal allenyl chem-
istry see: (a) Doherty, S.; Corrigan, J . F.; Carty, A. J .; Sappa, E. Adv.
Organomet. Chem. 1995, 37, 39. (b) Wojcicki, A. New J . Chem. 1994,
18, 61. For specific examples see: (c) Baize, M. W.; Blosser, P. W.;
Plantevin, V.; Schimpff, D. G.; Gallucci, J . C.; Wojcicki, A. Organome-
tallics 1996, 15, 164. (d) Baize, M. W.; Plantevin, V.; Gallucci, J . C.;
Wojcicki, A. Inorg. Chim. Acta 1995, 235. 1. (e) Ogoshi, S.; Tsutsumi,
K.; Kurosawa, H. J . Organomet. Chem. 1995, 493, C19. (f) Su, C.-C.;
Chen, J .-T.; Lee, G.-H.; Wang, Y. J . Am. Chem. Soc. 1994, 116, 4999.
(g) Huang, T.-M.; Chen, J .-T.; Lee, G.-H.; Wang, Y. J . Am. Chem. Soc.
1993, 115, 1170. (h) Blosser, P. W.; Schimpff, D. G.; Gallucci, J . C.;
Wojcicki, A. Organometallics 1994, 12, 1993. (i) Huang, T.-M.; Hsu,
R.-H.; Yang, C.-S.; Chen, J .-T.; Lee, G.-H.; Wang, Y. Organometallics
1994, 13, 3657. (j) Plantevin, V.; Blosser, P. W.; Gallucci, J . C.; Wojcicki,
A. Organometallics 1994, 13, 3651.
(17) (a) Mealli, C.; Proserpio, D. M. J . Chem. Educ. 1990, 67, 399.
(b) Hoffmann, R.; Lipscomb, W. N. J . Chem. Phys. 1962, 36, 2179, 3489.
(c) Hoffmann, R. J . Chem. Phys. 1963, 39, 1397.
(18) Doherty, S.; Corrigan, J . F.; Waugh, M. Unpublished results.

“Phosphine Tethered” Allene and Alkenyl Complexes
Organometallics, Vol. 15, No. 25, 1996 5307
dppm had dissolved, stirring was stopped and the reaction
mixture left to stand overnight, during which time the solution
changed from yellow to orange-red. After 20 h the large
quantity of crystalline material deposited on the bottom of the
flask was isolated and dried in vacuo to afford 3 in 60% yield
(0.160 g). IR (ν(CO), cm-1, CH2Cl2): 2022 m, 1982 m, 1921 s.
large component centered on CR, suggesting that the
selectivity of 1 for nucleophilic attack at this carbon is
under orbital control. Thus, in contrast to [Ru2(CO)6-
(µ-PPh2){µ-η1:η2R,â-(Ph)CRdCâdCγH2}], in the absence of
steric congestion, CR in 1 and 2 is, at least for phospho-
rus-based nucleophiles, the preferred site of attack.
Other significant contributions to the LUMO include
Fe-CO nonbonding interactions and a small contribu-
tion to Cγ.
2
31P{1H} NMR (202 MHz, CD2Cl2, δ): 75.6 (ABX, J PP ) 96.9
Hz, 2J PP ) 54.0 Hz, FesPPh2), 73.7 (ABX, 2J PP ) 96.9 Hz, 2J PP
2
2
) 29.6 Hz, µ-PPh2), 37.8 (ABX, J PP ) 54.0 Hz, J PP ) 29.6
Hz, CsPPh2sC). 1H NMR (500.1 MHz, CD2Cl2, δ): 8.0-7.0
(m, C6H5, 30 H), 6.00 (br, s, 1H, CdCHaHb), 5.41 (br, s, 1H,
CdCHaHb), 3.31 (m, 1H, PsCH2sP), 2.01 (m, 2H, PsCH2sP
and HCdC). 13C{1H} NMR (125.1 MHz, CDCl3, δ): 216.8 (d,
Con clu sion
The diiron allenyl complex [Fe2(CO)6(µ-PPh2){µ-η1:
η2R,â-(H)CRdCâdCγH2}] (1) reacts with bis(diphenylphos-
phino)methane to afford, in the first instance, [Fe2(CO)5-
(µ-PPh2){η1(P):η2(C)-Ph2PCH2PPh2(H)CdCdCH2}] (3),
which, when left standing in toluene, slowly decarbo-
nylates to give [Fe2(CO)5(µ-PPh2){µ-η1(P):η1(C):η2(C)-
Ph2PCHPPh2(H)CdCCH3}] (4). In contrast, dppm re-
acts with [Fe2(CO)6(µ-StBu){µ-η1:η2R,â-(H)CRdCâdCγH2}]
(2) to afford the isomeric σ-π-alkenyl complexes [Fe2-
(CO)5(µ-St Bu){µ-η1(P):η1(C):η2(C)-Ph2PCHPPh2(H)-
CdCCH3}] (5a ) and [Fe2(CO)5(µ-StBu){µ-η1(P):η1(C):
η2(C)-Ph2PCHPPh2CH2CdCH2}] (5b). In each case the
alkenyl ligand in 4, 5a , and 5b presumably results from
nucleophilic attack at CR of the allenyl ligand and
activation of a dppm methylene carbon-hydrogen bond
in an intermediate η2-dppm-functionalized allene com-
plex, coupled with hydrogen migration to either Cγ (4,
5a ) or CR (5b). These studies support our previous
report of regiospecific nucleophilic attack of protic
phosphines at CR of the allenyl ligand in [Fe2(CO)6(µ-
PPh2){µ-η1:η2R,â-(H)CRdCâdCγH2}] (1), although, in con-
trast to phosphines with labile PsH bonds, dppm reacts
via activation of its methylene CsH bond with hydrogen
migration to the σ-η-hydrocarbon. These results further
broaden the wealth of reactivity associated with transi-
tion-metal allenyl complexes. Additionally, we have
identified new reaction pathways for dppm, a ligand
that has until recently been assumed to adopt a role as
an innocent spectator. We anticipate that new and
exciting developments will continue to evolve from
future endeavors in this area.
2
2J PC ) 14.3 Hz, CO), 215.2 (d, J PC ) 12.0 Hz, CO), 147.5 (dd,
2
2J PC ) 62.9 Hz, J PC ) 15.3 Hz, CdCH2), 136-127 (m, C6H5),
1
1
121.0 (s, CCdCH2), 25.2 (dd, J PC ) 69.9 Hz, J PC ) 5.7 Hz,
1
PCH2P), 18.2 (d, J PC ) 65.3 Hz, CHCdCH2). Anal. Calcd
for C46H35Fe2O6P3: C, 62.16; H, 3.97. Found: C, 62.65; H, 4.19.
UV P h otolysis of [F e2(CO)6(µ-P P h 2){η1(P ):η2(C)-P h 2-
P CH2P P h 2-(H)CdCdCH2}] (4). A solution of 3 (0.120 g, 0.14
mmol) in toluene (150 mL) was irradiated for 30 min, during
which time the color changed from pale yellow to deep orange.
The solvent was removed under reduced pressure to afford an
orange solid which when crystallized from dichloromethane/
n-hexane gave 4 in 90% yield (0.105 g). IR (ν(CO), cm-1
C6H14): 2046 w, 2030 s, 1974 s, 1953 m, 1917 w. 31P{1H} NMR
,
2
3
(202 MHz, CDCl3, δ): 185.5 (dd, J PP ) 63.0 Hz, J PP ) 39.0
2
2
Hz, µ-PPh2), 66.0 (dd, J PP ) 122.0 Hz, J PP ) 63.0 Hz,
2
3
FesPPh2), 34.2 (dd, J PP ) 122.0 Hz, J PP ) 39.0 Hz,
CsPPh2sC). 1H NMR (500.1 MHz, CDCl3, δ): 8.0-7.1 (m,
30H, C6H5), 2.47 (s, 3H, CdCCH3), 1.92 (q, 2J PH ) 3J PH ) 11.0
2
2
Hz, 1H, HCdCCH3), 1.65 (dd, J PH ) 13.7 Hz, J PH ) 8.5 Hz,
1H, PsCHsP) 13C{1H} NMR (125.1 MHz, CDCl3, δ): 220.4
2
2
(d, J PC ) 24.0 Hz, CO), 217.0 (d, J PC ) 22.0 Hz, CO), 211.3
(s, CO), 197.5 (d, 2J PC ) 11.1 Hz, CdCMe), 145-128 (m, C6H5),
1
2
56.5 (dd, J PC ) 75.3 Hz, J PC ) 9.8 Hz, HCdCMe), 40.4 (br
1
1
m, HCdCCH3), 3.2 (dd, J PC ) 133.4 Hz, J PC ) 63.7 Hz,
Ph2PCHPPh2). Anal. Calcd for C45H35Fe2O5P3: C, 62.79; H,
4.10. Found C, 62.80; H, 4.23.
P r ep a r a t ion of [F e2(CO)5(µ-St Bu ){µ-η1(P ):η1(C):η2(C)-
P h 2P C(H)P P h 2(H)CdCCH3}] (5a ) a n d [F e2(CO)5(µ-StBu )-
{µ-η1(P ):η1(C):η2(C)-P h 2P CHP P h 2CH2CdCH2}] (5b). A so-
lution of dppm (0.245 g, 0.64 mmol) in diethyl ether (20 mL)
was added via cannula to a rapidly stirred solution of
[Fe2(CO)6(µ-StBu){µ-η1:η2R,â-(H)CRdCâdCγH2}] (0.260 g, 0.64
mmol) in diethyl ether (30 mL) with monitoring of the reaction
by TLC and IR spectroscopy. A deep cherry red color appeared
immediately, and the reaction was complete within minutes.
After the solvent was removed, the resultant oily residue was
extracted with hexane (3 × 30 mL) to give a clear red solution
which upon concentration (∼10 mL) and cooling at -20 °C
afforded a mixture of deep red (5a ) and orange (5b) crystals
in a combined yield of 69% (0.336 g). Isomers 5a and 5b were
separated mechanically under an optical microscope.
Exp er im en ta l Section
Gen er a l P r oced u r es. Unless otherwise stated, all ma-
nipulations were carried out in an inert-atmosphere glovebox
or by using standard Schlenk line techniques. Diethyl ether
and hexane were distilled from Na/K alloy, tetrahydrofuran
from potassium, and dichloromethane from CaH2. CDCl3 was
predried with CaH2 and vacuum-transferred and stored over
4 Å molecular sieves. Infrared spectra were recorded on a
Mattson Genesis FTIR spectrometer operating WINFIRST
software. Ultraviolet photolysis was carried out using a
Hanovia medium-pressure lamp. Bis(diphenylphosphino)-
methane, dodecacarbonyltriiron, and pentacarbonyliron were
purchased from Strem Chemical Co. and used without further
purification. The allenyl complexes [Fe2(CO)6(µ-PPh2){µ-η1:
η2R,â-(H)CRdCâdCγH2}]8 and [Fe2(CO)6(µ-StBu){µ-η1:η2R,â-(H)-
CRdCâdCγH2}]19 were prepared as previously described.
P r ep a r a tion of [Fe2(CO)6(µ-P P h 2){η1(P ):η2(C)-P h 2P CH2-
P P h 2(H)CdCdCH2}] (3). A slight excess of dppm (0.115 g,
0.35 mmol) was added to a rapidly stirred solution of 1 (0.150
g, 0.3 mmol) in toluene/diethyl ether (30/30 mL). After all the
Compound 5a : IR (ν(CO), cm-1, C6H14) 2038 s, 1984 s, 1965
2
s, 1916 m; 31P{1H} NMR (202 MHz, CDCl3, δ) 61.8 (d, J PP
)
2
112.0 Hz, FesPPh2), 25.9 (d, J PP ) 112.0 Hz, CsPPh2sC);
3
3
1H NMR (500.1 MHz, C6D6, δ) 8.35 (dd, J HH ) 7.1 Hz, J PH
)
8.0 Hz, 2H, ortho), 8.31 (dd, 3J HH ) 8.3 Hz, 3J PH ) 9.4 Hz, 2H,
ortho), 8.11 (dd, 2J HH ) 8.4 Hz, 3J PH ) 9.1 Hz, 2H, ortho), 7.80
(m, 2H, ortho), 7.5-7.1 (m, 12H, C6H5), 2.85 (d, 4J PH ) 4.2 Hz,
2
3
3H, CH3), 2.83 (dd, J PH ) 16.0 Hz, J PH ) 11.2 Hz, 1H,
2
2
CHdCCH3), 1.94 (dd, J PH ) 13.0 Hz, J PH ) 8.9 Hz, 1H,
PsCHsP), 1.61 (s, 9H, C(CH3)3); 13C{1H} NMR (125.1 MHz,
2
2
CDCl3, δ) 220.0 (d, J PC ) 24.0 Hz, CO), 217.0 (d, J PC ) 22.0
Hz, CO), 211.0 (s, CO), 198.3 (d, 2J PC ) 10.0 Hz, CdCMe), 145-
128 (m, C6H5), 57.9 (d, J PC ) 75.0 Hz, HCdCMe), 48.7 (s,
1
2
2
SC(CH3)3), 41.3 (dd, J PC ) 11.3 Hz, J PC ) 3.8 Hz, HCCCH3),
1
1
33.2 (s, SC(CH3)3), 8.6 (dd, J PC ) 135.7 Hz, J PC ) 66.6 Hz,
Ph2PCHPPh2). Anal. Calcd for C37H34Fe2O5P2S: C, 58.20; H,
4.48. Found C, 58.57; H, 4.13.
(19) Seyferth, D.; Womack, C. M.; Dewan, J . C. Organometallics
1989, 8, 430.

5308 Organometallics, Vol. 15, No. 25, 1996
Doherty et al.
Ta ble 5. Su m m a r y of Cr ysta l Da ta a n d Str u ctu r e Deter m in a tion for Com p ou n d s 3, 4, 5a , a n d 5b
3‚1/2 toluene
4‚CH2Cl2‚1/2 hexane
5a
5b
mol formula
fw
C46H33Fe2O6P3‚0.5C7H8 C45H35Fe2O5P3‚CH2Cl2‚0.5C6H14 C37H34Fe2O5P2S
C37H34Fe2O5P2S
764.3
932.4
988.4
764.3
temp, K
cryst syst
space group
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
160
triclinic
P1h
160
triclinic
P1h
160
monoclinic
P21
17.5589(14)
11.2530(9)
18.5709(15)
160
triclinic
P1h
11.3498(12)
12.0803(13)
17.730(2)
87.624(3)
78.363(3)
65.475(3)
2163.8(4)
2
1.431
8.32
0.39 × 0.06 × 0.06
0.790-0.952
4.3-50.0
11 402
7517
0.0436
0.0370, 12.4648
0.0009(4)
575
65
0.1786
0.0746 (5667)
1.107
11.8979(11)
12.2293(11)
15.9827(15)
99.440(2)
103.827(2)
96.506(2)
2199.1(4)
2
1.489
9.38
0.22 × 0.17 × 0.06
0.671-0.928
2.7-50.0
12 612
7556
0.0621
0.0638, 0
0.0008(5)
587
61
0.1566
0.0687 (4407)
0.982
+0.70, -0.57
10.2099(13)
10.7921(14)
18.496(2)
78.025(3)
85.654(3)
62.876(4)
1774.0(4)
2
106.046(2)
3526.5(5)
4
1.440
10.14
Z
D
calcd, g cm-3
1.431
10.08
µ(Mo KR), cm-1
cryst size, mm
0.72 × 0.46 × 0.45 0.34 × 0.22 × 0.06
transmissn coeff range
scan range (2θ), deg
no. of rflns measd
no. of unique rflns
Rint
0.726-0.887
2.3-45.0
15 053
0.796-0.959
4.3-57.0
10 987
7687
0.0368
0.0387, 0.8536
0.0008(4)
434
9114
0.0391
0.0272, 55.4463
0.0006(2)
858
75
0.1899
0.0749 (8996)
1.155
+1.82, -0.68
weighting parametersa a, b
extinction coeff xb
no. of variables
no. of restraints
Rw (all data)c
0
0.0957
0.0407 (5306)
1.011
R (“observed” data)d
GOFe
max, min electron density, e Å-3 +1.50, -0.96
+0.39, -0.34
a
2
b
2
w-1 ) σ2(Fo2) + (aP)2 + bP, where P ) (Fo + 2Fc2)/3. Fc′ ) Fc(1 + xFc2λ3/sin 2θ)-1/4
.
c Rw ) {∑[w(Fo - Fc2)2]/∑[w(Fo2)2]}1/2 for all
data. R ) ∑||Fo| - |Fc||/∑|Fo| for reflections having Fo > 2σ(Fo2). e GOF ) [∑w(Fo - Fc2)2/((no. of unique rflns) - (no. of variables))]1/2
.
d
2
2
Compound 5b: IR (ν(CO), cm-1, C6H14): 2053 sh, 2038 m,
1976 s, 1920 w; 31P{1H} NMR (202 MHz, CDCl3, δ) 60.6 (d,
2J PP ) 72.0 Hz, FesPPh2), 30.4 (d, 2J PP ) 72.0 Hz, CsPPh2sC);
1H NMR (500.1 MHz, C6D6, δ) 7.8-7.1 (m, C6H5, 20 H), 4.20
restraints on geometry and displacement parameters; hydro-
gen atoms were not included. For 4, disordered CH2Cl2 and
n-hexane molecules were located and refined, also with ap-
propriate restraints and with H atoms for CH2Cl2 only. The
structure of 5a was found to be partially twinned racemically.
Programs used were Siemens SMART (control) and SAINT
(integration) software,20 SHELXTL,21 and local programs, on
Silicon Graphics Indy workstations and personal computer
systems.
2
2
2
(t, J HH ) 12.4 Hz, J PH ) 4.2 Hz, 1H, CHaHb), 3.31 (t, J HH
)
2
2
12.7 Hz, J PH ) 4.2 Hz, 1H, CHaHb), 3.15 (d, br, J HH ) 2.0
2
Hz, 1H, CHcHd), 2.65 (d, br, J HH ) 2.0 Hz, 1H, CHcHd), 1.80
(t, J PC ) 7.8 Hz, 1H, PsCHsP), 0.98 (s, 9H, C(CH3)3). Anal.
2
Calcd for C37H34Fe2O5P2S: C, 58.20; H, 4.48. Found: C, 58.61;
H, 4.27.
Cr ysta l Str u ctu r e Deter m in a tion of 3, 4, 5a , a n d 5b.
Single crystals of each compound were obtained by crys-
tallization: from toluene/diethyl ether for 3 and CH2Cl2/n-
hexane for 4, 5a , and 5b. Crystals were examined on a
Siemens SMART CCD area-detector diffractometer with graph-
ite-monochromated Mo KR radiation (λ ) 0.710 73 Å). Cell
parameters were refined from the observed setting angles of
all strong reflections in each complete data set. Intensities
were integrated from series of ω-rotation exposures with
different φ-angles chosen to generate more than a hemisphere
of data, each exposure covering 0.3° in ω. Analysis of repeated
and symmetry-equivalent data indicated no significant inten-
sity decay and formed the basis of empirical absorption
corrections.
The structures were solved by direct methods and refined
by full-matrix least squares on F2 values for all unique data
(see Table 5 for details). All non-hydrogen atoms except for
hexane solvent were assigned anisotropic displacement pa-
rameters. Hydrogen atoms were constrained to ideal positions
with a riding model and with Uiso(H) set at 1.2 (1.5 for methyl
groups) times Ueq for the parent atom, except for allene and
alkene CH and CH2, for which positions were refined freely.
For 3, a disordered toluene was located and refined with
Ack n ow led gm en t. We thank the University of
Newcastle, the Nuffield Foundation, and the Royal
Society for financial support (S.D.) and the EPSRC for
funding for a diffractometer (W.C.). We thank Dr. J ohn
F. Corrigan for his assistance with the molecular orbital
calculations and helpful discussions.
Su p p or tin g In for m a tion Ava ila ble: For 3, 4, 5a , and
5b, details of the structure determination (Tables S1, S6, S11,
and S16), non-hydrogen atom positional parameters (Tables
S2, S7, S12, and S17), bond distances and angles (Tables S3,
S8, S13, and S18), anisotropic displacement parameters
(Tables S4, S9, S14, and S19), and hydrogen atom parameters
(Tables S5, S10, S15, and S20) (36 pages). Ordering informa-
tion is given on any current masthead page. Observed and
calculated structure factors are available from the authors
upon request.
OM960502E
(20) SMART and SAINT software for CCD diffractometers, from
Siemens Analytical X-ray Instruments Inc., Madison, WI, 1995.
(21) Sheldrick, G. M. SHELXTL Manual, Version 5, Siemens
Analytical X-ray Instruments: Madison, WI, 1994.