Novel synthesis, X-ray crystal structures, and spectroscopic properties of metalated hypervalent phosphorus compounds, Cp(CO)LFe{P(OC6H4Y)OC6H4Z} (L = CO, P(OPh)3, P(OMe)3, PMe3; Y, Z = NH, NMe, O)

Article abstract of DOI:10.1021/om980384q

Iron phosphorane complexes, Cp(CO)₂Fe{P(OC₆H₄Y)₂} (1a, Y = NH; 1b, Y = NMe; 3, Y = O), have been prepared from [Cp(CO)₂Fe{P(OPh)₃}]PF₆, o-HOC₆H₄YH, and a Lewis base. Cp(CO)₂Fe{P(OC₆H₄O)(OC₆H ₄NR)} (2a, R = H; 2b, R = Me) having two different chelates on the phosphorus has been prepared from [Cp(CO)₂Fe{P(OC₆H₄O)(OPh)}]PF₆, o-HOC₆H₄-NRH, and a Lewis base. These reactions involve nucleophilic attacks of an organic nucleophile at a trivalent phosphorus coordinated to an iron and substitution on the phosphorus. During the course of preparation of 1b, [Cp(CO)₂Fe{P(OC₆H₄NMe)-(OC₆H ₄NMeH)}]PF₆ (4) was isolated, which corresponds to one of the intermediates on the reaction pathways to give 1-3. 4 reacts with a Lewis base to give 1b. The reaction of hydridophosphorane HP(OC₆H₄NH)₂ with n-BuLi leads to NH proton abstraction to give the amide HP(OC₆H₄NH)(OC₆H₄N^-), which then reacts with Cp(CO)LFeCl to yield Cp(CO)-LFe{P(OC₆H₄NH)₂} (5, L = P(OPh)₃; 6, L = P(OMe)₃; 7, L = PMe₃) by an apparent 1,2-proton migration. The X-ray structures of 1b, 2b, and 4 were determined. 1b and 2b have slightly distorted trigonal-bipyramidal geometries around the phosphorus with the iron fragment in the equatorial position and have P-O_eq bonds longer than those of organophosphoranes, indicating that the Cp(CO)₂Fe fragment serves as a strong π donor. The Fe-P(phosphorane) bond rotates freely in solution even at -50°C. A Berry pseudorotation around the phosphorane phosphorus does not occur for 1a,b, 2a,b, and 5-7, whereas it does for 3.

Full text of DOI:10.1021/om980384q

3522
Organometallics 1998, 17, 3522-3531
Novel Syn th esis, X-r a y Cr ysta l Str u ctu r es, a n d
Sp ectr oscop ic P r op er ties of Meta la ted Hyp er va len t
P h osp h or u s Com p ou n d s,
Cp (CO)LF e{P (OC6H4Y)(OC6H4Z)} (L ) CO, P (OP h )3,
P (OMe)3, P Me3; Y, Z ) NH, NMe, O)
Kazuyuki Kubo, Hiroshi Nakazawa,* Tsutomu Mizuta, and Katsuhiko Miyoshi*
Department of Chemistry, Faculty of Science, Hiroshima University,
Higashi-Hiroshima 739-8526, J apan
Received May 15, 1998
Iron phosphorane complexes, Cp(CO)2Fe{P(OC6H4Y)2} (1a , Y ) NH; 1b, Y ) NMe; 3, Y )
O), have been prepared from [Cp(CO)2Fe{P(OPh)3}]PF6, o-HOC6H4YH, and a Lewis base.
Cp(CO)2Fe{P(OC6H4O)(OC6H4NR)} (2a , R ) H; 2b, R ) Me) having two different chelates
on the phosphorus has been prepared from [Cp(CO)2Fe{P(OC6H4O)(OPh)}]PF6, o-HOC6H4-
NRH, and a Lewis base. These reactions involve nucleophilic attacks of an organic
nucleophile at a trivalent phosphorus coordinated to an iron and substitution on the
phosphorus. During the course of preparation of 1b , [Cp(CO)2Fe{P(OC6H4NMe)-
(OC6H4NMeH)}]PF6 (4) was isolated, which corresponds to one of the intermediates on the
reaction pathways to give 1-3. 4 reacts with a Lewis base to give 1b. The reaction of
hydridophosphorane HP(OC6H4NH)2 with n-BuLi leads to NH proton abstraction to give
the amide HP(OC6H4NH)(OC6H4N-), which then reacts with Cp(CO)LFeCl to yield Cp(CO)-
LFe{P(OC6H4NH)2} (5, L ) P(OPh)3; 6, L ) P(OMe)3; 7, L ) PMe3) by an apparent 1,2-
proton migration. The X-ray structures of 1b, 2b, and 4 were determined. 1b and 2b have
slightly distorted trigonal-bipyramidal geometries around the phosphorus with the iron
fragment in the equatorial position and have P-Oeq bonds longer than those of organophos-
phoranes, indicating that the Cp(CO)2Fe fragment serves as a strong π donor. The Fe-
P(phosphorane) bond rotates freely in solution even at -50 °C. A Berry pseudorotation
around the phosphorane phosphorus does not occur for 1a ,b, 2a ,b, and 5-7, whereas it
does for 3.
In tr od u ction
philic attack of an electron-deficient transition-metal
fragment at a phosphoranide6 (Sb7) (eqs 1-5). Some
other preparative methods8 and review articles9 have
been reported.
Pentacoordinate phosphorus compounds (phospho-
ranes) are one class of hypervalent compounds violating
the octet rule and have attracted considerable attention
in theoretical and experimental studies. In contrast to
the widely explored chemistry of organic phosphoranes,
a limited number of examples have been known to date
for metallaphosphoranes, though they are also consid-
ered to be an important class of hypervalent phosphorus
compounds.
The preparative methods for metallaphosphoranes
which have been developed are roughly classified as
follows: (1) deprotonation1 and (2) protonation2 at a
nitrogen in polycyclic species with phosphine- and/or
amine-metal bonds, (3) oxidative addition of halogen
to transition-metal phosphide complexes3 (Sb and As4),
(4) nucleophilic substitution at a phosphorane phospho-
rus atom by a transition-metal anion,5 and (5) electro-
(1) (a) Wachter, J .; Mentzen, B. F.; Riess, J . G. Angew. Chem., Int.
Ed. Engl. 1981, 20, 284. (b) Vierling, P.; Riess, J . G. J . Am. Chem.
Soc. 1981, 103, 2466. (c) J eanneaux, F.; Grand, A.; Riess, J . G. J . Am.
Chem. Soc. 1981, 103, 4272. (d) Dupart, J .-M.; Grand, A.; Pace, S.;
Riess, J . G. J . Am. Chem. Soc. 1982, 104, 2316. (e) Vierling, P.; Riess,
J . G. J . Am. Chem. Soc. 1984, 106, 2432. (f) Dupart, J .-M.; Grand, A.;
Riess, J . G. J . Am. Chem. Soc. 1986, 108, 1167. (g) Vierling, P.; Riess,
J . G. Organometallics 1986, 5, 2543. (h) Vierling, P.; Riess, J . G.;
Grand, A. Inorg. Chem. 1986, 25, 4144. (i) Khasnis, D. V.; Burton, J .
M.; Zhang, H.; Lattman, M. Organometallics 1992, 11, 3745.
(2) (a) Khasnis, D. V.; Lattman, M.; Siriwardane, U. Inorg. Chem.
1989, 28, 681. (b) Khasnis, D. V.; Lattman, M.; Siriwardane, U. Inorg.
Chem. 1989, 28, 2594. (c) Khasnis, D. V.; Lattman, M.; Siriwardane,
U. J . Chem. Soc., Chem. Commun. 1989, 1538. (d) Khasnis, D. V.;
Lattman, M.; Siriwardane, U.; Chopra, S. K. J . Am. Chem. Soc. 1989,
111, 3103. (e) Khasnis, D. V.; Lattman, M.; Siriwardane, U. Organo-
metallics 1991, 10, 1326. (f) Khasnis, D. V.; Lattman, M.; Siriwardane,
U.; Zhang, H. Organometallics 1992, 11, 2074.
S0276-7333(98)00384-7 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 07/11/1998

Metalated Hypervalent Phosphorus Compounds
Organometallics, Vol. 17, No. 16, 1998 3523
the nature of the Fe-phosphorane P bond. A part of
this work has been previously communicated.10
Resu lts a n d Discu ssion
F or m a tion of Cp (CO)2F e{P (OC6H4Y)(OC6H4Z)}.
The synthesis and characterization of the metallaphos-
phoranes are described with Cp(CO)2Fe{P(OC6H4NH)2}
(1a ) as an example. [Cp(CO)2Fe{P(OPh)3}]PF6 was
treated with a reaction mixture of 2 equiv of o-HOC6H4-
NH2 and 1 equiv of n-BuLi to give a yellow powder of
1a in considerable yield (56%) (eq 6).
The formation of 1a was verified by the following
spectroscopic data. (i) In the IR spectrum, two absorp-
tion bands due to νCO were observed at 2026 and 1977
cm-1, indicating that the product is electrically neutral.
(ii) The presence of a P(OC6H4NH)2 group in the product
was supported by the observation of a singlet at 24.18
ppm in the proton-decoupled 31P NMR spectrum. The
resonance is at a higher field by ca. 136 ppm than that
of the starting material, indicating that the phosphorus
in the product has a higher valency, and it became a
triplet (J PH ) 19.9 Hz) in the proton-nondecoupled
spectrum, showing the presence of two NH groups on
the phosphorus. (iii) A broad doublet at 5.20 ppm (J PH
) 17.2 Hz) assigned to NH was observed in the 1H NMR
spectrum together with Cp and substituted phenyl ring
signals, as expected.
With some modifications, Cp(CO)2Fe{P(OC6H4NMe)2}
(1b; 87% yield) (eq 6) and Cp(CO)2Fe{P(OC6H4O)2} (3;
66% yield) (eq 8) were similarly prepared from [Cp-
(CO)2Fe{P(OPh)3}]PF6. Treatment of [Cp(CO)2Fe-
{P(OC6H4O)(OPh)}]PF6 with 1 equiv of o-HOC6H4NRH
in the presence of n-BuLi gave Cp(CO)2Fe{P(OC6-
H4O)(OC6H4NR)} (R ) H, 2a , 87% yield; R ) Me, 2b,
47% yield) (eq 7). Table 1 summarizes the IR (νCO) and
1H, 31P, and 13C NMR data for metallaphosphoranes
1a ,b, 2a ,b, and 3.
We herein report an unprecedented synthetic method
for metallaphosphoranes, Cp(CO)2Fe{P(OC6H4Y)-
(OC6H4Z)} (Cp ) η5-C5H5; Y, Z ) NH, NMe, O; although
the complex should be described as Cp(CO)2Fe{P-
(OC6H4Y)(OC6H4Z)}, the tie bars are omitted in this
paper for simplicity), involving the nucleophilic attack
of an organic nucleophile at a trivalent phosphorus
coordinated to a transition metal. Also reported is the
synthesis of Cp(CO)LFe{P(OC6H4NH)2} (L ) P(OPh)3,
P(OMe)3, PMe3) by the reaction of Cp(CO)LFeCl with
[HP(OC6H4NH)(OC6H4N-)] involving an apparent 1,2-
proton migration from P to N. On the basis of the
structural and spectroscopic data for a series of iron-
phosphorane complexes formulated as Cp(CO)LFe-
{P(OC6H4Y)(OC6H4Z)}, we discuss the effect of substit-
uents on both the iron and the phosphorus atoms on
(3) (a) Ebsworth, E. A. V.; McManus, N. T.; Pilkington, N. J .; Rankin,
D. W. H. J . Chem. Soc., Chem. Commun. 1983, 484. (b) Ebsworth, E.
A. V.; Holloway, J . H.; Pilkington, N. J .; Rankin, D. W. H. Angew.
Chem., Int. Ed. Engl. 1984, 23, 630.
(4) Malisch, W.; Kaul, H. A.; Gross, E.; Thewalt, U. Angew. Chem.,
Int. Ed. Engl. 1982, 21, 549.
(5) (a) Lattman, M.; Anand, B. N.; Garrett, D. R.; Whitener, M. A.
Inorg. Chim. Acta 1983, 76, L139. (b) Lattman, M.; Morse, S. A.;
Cowley, A. H.; Lasch, J . G.; Norman, N. C. Inorg. Chem. 1985, 24,
1364. (c) Anand, B. N.; Bains, R.; Usha, K. J . Chem. Soc., Dalton Trans.
1990, 2315.
(6) Chopra, S. K.; Martin, J . C. Heteroat. Chem. 1991, 2, 71.
(7) Yamamoto, Y.; Okazaki, M.; Wakisaka, Y.; Akiba, K. Organo-
metallics 1995, 14, 3364.
It should be noted in these reactions that the valence
of the phosphorus is formally expanded from III to V
presumably without Fe-P bond cleavage; that is, the
nature of the Fe-P bond changes formally from dative
to covalent.
The reaction mechanism is proposed in Scheme 1.
[o-OC6H4YH]-, produced from o-HOC6H4YH and a base,
nucleophilically attacks the phosphorus atom of [Cp-
(CO)2Fe{P(OPh)3}]+ to give a metallaphosphorane (A),
(8) (a) Lattman, M.; Chopra, S. K.; Cowley, A. H.; Arif, A. M.
Organometallics 1986, 5, 677. (b) Burns, E. G.; Chu, S. S. C.; Meester,
P.; Lattman, M. Organometallics 1986, 5, 2383. (c) Lattman, M.; Burns,
E. G.; Chopra, S. K.; Cowley, A. H.; Arif, A. M. Inorg. Chem. 1987, 26,
1926.
(9) (a) Montgomery, C. D. Phosphorus, Sulfur Silicon Relat. Elem.
1993, 84, 23. (b) Dillon, K. B. Chem. Rev. 1994, 94, 1441.
(10) Nakazawa, H.; Kubo, K.; Miyoshi, K. J . Am. Chem. Soc. 1993,
115, 5863.

3524 Organometallics, Vol. 17, No. 16, 1998
Kubo et al.
Sch em e 1
followed by release of OPh- to yield a cationic iron
complex (B). The released OPh- abstracts the YH
proton of B to yield the Y- group, which then nucleo-
philically attacks the P atom to give C, followed by
release of OPh- to obtain D. This OPh- reacts with the
remaining unreacted o-HOC6H4YH to give [o-OC6H4-
YH]-, which undergoes similar reactions leading finally
to the formation of Cp(CO)2Fe{P(OC6H4Y)2}. In eq 6,
2 equiv of o-HOC6H4YH was necessary, but 1 equiv of
a base based on the cationic iron complex was sufficient,
which is consistent with the mechanism. The proposed
intermediates A-D have not been observed even spec-
troscopically, presumably due to their high reactivity.
It is well-known for cationic transition-metal carbonyl
complexes that a Lewis base nucleophilically attacks a
coordinated carbonyl carbon (eq 9). For example, the
phosphorus species has not been observed. Our results
in this paper point to the possibility of such a reaction.
In the reaction of [Cp(CO)2Fe{P(OPh)3}]PF6, o-HO-
C6H4NMeH, and n-BuLi in the hope of 1b formation,
we encountered the isolation of [Cp(CO)2Fe{P(OC6H4-
NMe)(OC6H4NMeH)}]PF6 (4), which has a trivalent
phosphorus ligand with a dangling NMeH group. The
IR and 31P NMR spectra of the reaction mixture show
the formation of 1b. However, removal of volatile
components from the mixture and then addition of ether
to the residue caused the formation of 4 as a yellow
powder (67% yield). The IR spectrum exhibits two CO
stretching bands at 2076 and 2033 cm-1, indicating the
formation of a cationic complex. The 31P NMR spectrum
shows a singlet at 173.56 ppm, which is at 157 ppm
(15) The 31P NMR spectrum measured after stirring of the reaction
mixture of [Cp(CO)2Fe{P(OPh)3}]PF6 and [o-OC6H4NH2]- at room
temperature for 1 h showed a strong singlet at 175.34 ppm together
with singlets for the starting complex and the final product (1a ), and
the ratio was approximately 7:1:1. The complex may be an aryloxy
carbonyl complex, Cp(CO)Fe{C(O)OC6H4NH2}{P(OPh)3}, on the basis
of reactions of similar complexes with other anions.11-14 The IR
spectrum of the reaction mixture also supports the formation of the
aryloxy carbonyl complex: νCO 1953 cm-1 for the terminal CO (νCO for
the FeC(O)OC6H4NH2 fragment was not identified due to the complex-
ity in the region). The aryloxy carbonyl complex disappeared after
stirring overnight at room temperature, and the amount of 1a
increased instead. Therefore, it is highly likely that the reaction
pathway to the aryloxy carbonyl complex is reversible; i.e., it equili-
brates with the starting complex, whereas the reaction pathway to 1a
is irreversible. In our case, an aryloxy carbonyl complex may be a
kinetic product and a metallaphosphorane is a thermodynamic product.
(16) Mason, M. R.; Verkade, J . G. Organometallics 1992, 11, 2212.
(17) Nakazawa, H.; Kubo, K.; Kai, C.; Miyoshi, K. J . Organomet.
Chem. 1992, 439, C42.
reactions with -OR,11,12 -NR2,12 -OH,11,13 and -R14
anions give alkoxycarbonyl, carbamoyl, metallocarboxy-
lic acid, and acyl (aroyl) complexes, respectively. How-
ever, in our case, the reaction site is not a carbonyl
carbon but a phosphite phosphorus.15 Nucleophilic
attack of -F,16 -H,17 or -OH18 anion at a trivalent
phosphorus atom coordinated to a transition metal has
been proposed. However, the expected pentavalent
(11) Trautman, R. J .; Gross, D. C.; Ford, P. C. J . Am. Chem. Soc.
1985, 107, 2355.
(12) Angelici, R. J . Acc. Chem. Res. 1972, 5, 335.
(13) Gibson, D. H.; Ong, T.-S. J . Am. Chem. Soc. 1987, 109, 7191.
(14) (a) Casey, C. P. CHEMTECH 1979, 378. (b) Do¨tz, K. H. Angew.
Chem., Int. Ed. Engl. 1984, 23, 587.
(18) Nakazawa, H.; Kubo, K.; Tanisaki, K.; Kawamura, K.; Miyoshi,
K. Inorg. Chim. Acta 1994, 222, 123.

Metalated Hypervalent Phosphorus Compounds
Organometallics, Vol. 17, No. 16, 1998 3525
Ta ble 1. Sp ectr oscop ic Da ta
IR νCO
,
1H NMR,
ppm (in CDCl3)
31P NMR,
ppm (in THF)
complex cm-1 (in THF)
13C NMR, ppm (in CDCl3)
1a
2026
1977
4.94 (d, J PH ) 1.1 Hz, 5H, C5H5) 24.18 (t, J PH ) 19.9 Hz)
5.20 (d, J PH ) 17.2 Hz, 2H, NH)
6.60-6.66 (m, 8H, OC6H4N)
85.31 (s, C5H5)
108.55 (d, J PC ) 12.9 Hz, OC6H4N)
108.69 (s, OC6H4N)
118.73 (s, OC6H4N)
119.27 (s, OC6H4N)
132.46 (d, J PC ) 11.0 Hz, OC6H4N)
149.55 (d, J PC ) 5.5 Hz, OC6H4N)
210.96 (d, J PC ) 42.3 Hz, CO)
212.62 (d, J PC ) 44.1 Hz, CO)
1b
2024
1975
3.20 (d, J PH ) 7.7 Hz, 6H, NCH3) 16.29 (sep, J PH ) 7.6 Hz) 32.96 (d, J PC ) 3.8 Hz, NCH3)
4.86 (d, J PH ) 0.7 Hz, 5H, C5H5)
6.51-6.77 (m, 8H, OC6H4N)
84.67 (s, C5H5)
107.48 (s, OC6H4N)
107.60 (d, J PC ) 8.7 Hz, OC6H4N)
118.14 (s, OC6H4N)
119.05 (s, OC6H4N)
136.75 (d, J PC ) 16.1 Hz, OC6H4N)
149.44 (d, J PC ) 9.4 Hz, OC6H4N)
210.99 (d, J PC ) 44.1 Hz, CO)
213.09 (d, J PC ) 46.6 Hz, CO)
2a
2034
1988
5.01 (s, 5H, C5H5)
48.50 (d, J PH ) 21.3 Hz)
85.19 (s, C5H5)
5.52 (d, J PH ) 17.1 Hz, 1H, NH)
6.66-6.99 (m, 8H, OC6H4O and
OC6H4N)
108.74 (s, OC6H4O or OC6H4N)
108.85 (s, OC6H4O or OC6H4N)
109.41 (d, J PC ) 5.0 Hz, OC6H4O or OC6H4N)
111.14 (d, J PC ) 11.0 Hz, OC6H4O or OC6H4N)
118.60 (s, OC6H4O or OC6H4N)
118.98 (s, OC6H4O or OC6H4N)
119.84 (s, OC6H4O or OC6H4N)
122.24 (s, OC6H4O or OC6H4N)
131.33 (d, J PC ) 11.0 Hz, OC6H4O or OC6H4N)
143.74 (s, OC6H4O or OC6H4N)
148.41 (s, OC6H4O or OC6H4N)
149.36 (d, J PC ) 7.4 Hz, OC6H4O or OC6H4N)
210.28 (d, J PC ) 44.1 Hz, CO)
211.43 (d, J PC ) 44.1 Hz, CO)
2b
2033
1985
3.28 (d, J PH ) 8.1 Hz, 3H, NCH3) 45.39 (qua, J PH ) 6.1 Hz) 32.59 (d, J PC ) 4.4 Hz, NCH3)
4.96 (s, 5H, C5H5)
6.59-6.97 (m, 8H, OC6H4O and
OC6H4N)
84.94 (s, C5H5)
107.89 (d, J PC ) 1.9 Hz, OC6H4O or OC6H4N)
108.25 (d, J PC ) 9.3 Hz, OC6H4O or OC6H4N)
108.99 (d, J PC ) 1.8 Hz, OC6H4O or OC6H4N)
110.80 (d, J PC ) 11.2 Hz, OC6H4O or OC6H4N)
118.83 (s, OC6H4O or OC6H4N)
119.07 (s, OC6H4O or OC6H4N)
119.19 (s, OC6H4O or OC6H4N)
121.81 (s, OC6H4O or OC6H4N)
135.60 (d, J PC ) 17.4 Hz, OC6H4O or OC6H4N)
143.79 (s, OC6H4O or OC6H4N)
148.20 (d, J PC ) 3.1 Hz, OC6H4O or OC6H4N)
149.34 (d, J PC ) 9.4 Hz, OC6H4O or OC6H4N)
210.07 (d, J PC ) 44.1 Hz, CO)
211.89 (d, J PC ) 45.3 Hz, CO)
3
2042
1996
5.04 (s, 5H, C5H5)
6.81 (s, 4H, OC6H4O)
6.91 (s, 4H, OC6H4O)
73.51 (s)
85.17 (s, C5H5)
110.18 (d, J PC ) 9.2 Hz, OC6H4O)
120.81 (s, OC6H4O)
145.30 (s, OC6H4O)
209.83 (d, J PC ) 45.9 Hz, CO)
lower field than that of 1b, suggesting that the phos-
phorus adopts a lower valency. In the H NMR spec-
NaOPh to give 1b together with HOPh and NaPF6.
Actually, the reaction of 4 with NaOPh in THF was
confirmed to give 1b. In the cases of 1a , 2a , 2b, and 3,
the corresponding cationic complex was not obtained
even in an ether solution. The reason may be the high
solubility in ether of the cationic complex to be formed
and/or lower basicity of N or O atom(s) on the phospho-
rus of these complexes compared with the N basicity in
1b.
F or m a tion of Cp (CO)LF e{P (OC6H4NH)2}. Sys-
tematic change in the substituents from electron-
withdrawing groups to electron-donating groups on the
transition metal as well as on the phosphorane phos-
phorus may help in understanding the nature of the
1
trum, two methyl proton signals are observed; one is a
doublet due to coupling with phosphorus, and the other
is a singlet. The structure of 4 is confirmed by its X-ray
analysis (vide infra).
The isolated complex 4 corresponds to one of the
intermediates, which is, however, omitted in Scheme 1
for brevity. In a THF solution, 1b may be in equilibrium
with 4 but the equilibrium is considerably shifted
toward 1b (eq 10). Complex 4 is sparingly soluble in
ether, which results in the isolation of 4 in considerable
yield. If the H-N(1) proton in 4 is expected to be more
acidic than an H-O proton in HOPh, 4 would react with

3526 Organometallics, Vol. 17, No. 16, 1998
Kubo et al.
Ta ble 2. 31P NMR Da ta a
NMR, ppm
complex
1a
5
24.18 (t, J PH ) 19.9 Hz)
27.09 (dt, J PP ) 149.5 Hz, J PH ) 18.3 Hz, P(V))
169.31 (d, J PP ) 149.6 Hz, P(III))
5′
6
30.00 (dt, J PP ) 158.7 Hz, J PH ) 18.3 Hz, P(V))
170.41 (d, J PP ) 158.7 Hz, P(III))
33.89 (dt, J PP ) 150.9 Hz, J PH ) 18.2 Hz, P(V))
180.65 (d, J PP ) 150.9 Hz, P(III))
6′
7
35.34 (dt, J PP ) 165.5 Hz, J PH ) 18.9 Hz, P(V))
182.96 (d, J PP ) 164.2 Hz, P(III))
37.78 (d, J PP ) 104.6 Hz, P(III))
39.41 (dt, J PP ) 104.6 Hz, J PH ) 15.2 Hz, P(V))
38.11 (d, J PP ) 104.6 Hz, P(III))
7′
42.73 (dt, J PP ) 104.6 Hz, J PH ) 15.8 Hz, P(V))
a
In THF.
(J PH ) 814.8 and 21.3 Hz). Therefore, it can be said in
the reaction of HP(OC6H4NH)2 with a Lewis base that
the P-H bond remains intact and an amino proton is
selectively abstracted to give the amide HP(OC6H4NH)-
(OC6H4N-), where the remaining amino proton is shut-
tling rapidly between the two N atoms.
Fe-P(phosphorane) bond. Thus, we attempted to pre-
pare Cp(CO)LFe{P(OC6H4NH)2} (L ) phosphine, phos-
phite).
The reaction of [Cp(CO)LFe{P(OPh)3}]PF6 (L )
P(OPh)3, P(OMe)3, PMe3) with o-HOC6H4NH2 in the
presence of n-BuLi was first examined. Monitoring of
the reaction mixture by the 31P NMR spectra revealed
that several reactions take place simultaneously, but
the desired iron phosphorane complex was not obtained.
The replacement of CO (a good π acceptor) by L (an
electron-donating ligand compared with CO) makes the
P atom in a P(OPh)3 ligand electron-rich, which may
result in its resisting the nucleophilic attack of [o-OC6H4-
NH2]-.
The amide thus formed reacts with Cp(CO)LFeCl in
THF to give Cp(CO)LFe{P(OC6H4NH)2} (L ) P(OPh)3
(5), P(OMe)3 (6), PMe3 (7)). The phosphorane complex
is the main product, but some unidentified compounds
are also produced. Although several attempts to isolate
5 and 6 in a pure form failed, due to the difficulty of
purification without decomposition, the formation is
strongly supported by the 31P NMR data shown in Table
2. 7 could be isolated and the spectroscopic data were
obtained, though satisfactory elemental analysis data
could not be obtained due to its high reactivity. These
metallaphosphoranes show two doublets in the penta-
coordinate phosphorus region and two doublets in the
coordinating phosphite or phosphine region. The ob-
servation is rationalized by diastereomer formation due
to the Fe and P chiral centers. In the 31P NMR spectra
without proton irradiation, the two doublets in the
phosphorane region become two doublets of triplets,
which is consistent with the presence of an Fe-P(OC6H4-
NH)2 moiety.
We sought another preparative method and found
that the reaction of HP(OC6H4NH)2 with n-BuLi and
then Cp(CO)LFeCl leads to the formation of Cp(CO)-
LFe{P(OC6H4NH)2} (eq 11). In the reaction of HP-
In the reaction of HP(OC6H4NH)(OC6H4N-) with Cp-
(CO)LFeCl, if a nucleophilic attack of the amido nitrogen
on the iron takes place, the iron amido complex HP-
(OC6H4NH)(OC6H4N{FeL(CO)Cp}) would be formed.
This is not the case. Two explanations seem to be
possible. (i) HP(OC6H4NH)(OC6H4N{FeL(CO)Cp}) is
first formed, and then an H on the phosphorus and an
FeL(CO)Cp moiety exchange positions in some way. (ii)
Although only HP(OC6H4NH)(OC6H4N-) is observed in
the 31P NMR spectrum, a phosphoranide, -P(OC6H4NH)2,
exists in solution as an equilibrium species with the
amide, and the equilibrium lies on the side of the amide.
If the phosphoranide is much more reactive than the
amide toward Cp(CO)LFeCl, then the phosphoranide
selectively reacts to give an iron phosphorane complex
eventually as the main product. It is not clear now
which route is correct. However, route ii seems ap-
propriate because of our following observations. (a)
HP(OC6H4NH)(OC6H4N-) reacts with MeI to give
MeP(OC6H4NH)2 selectively. (b) For HP(OC6H4NMe)2,
an exchange reaction between an H on the phosphorus
and an Me on the nitrogen has not been observed.
X-r a y Str u ctu r es of 1b, 2b, a n d 4. The structures
of 1b, 2b, and 4 were determined by X-ray diffraction
(OC6H4NH)2 with n-BuLi, the product is not the phos-
phoranide P(OC6H4NH)2 but the amide HP(OC6H4NH)-
-
(OC6H4N-), which was deduced from the 31P NMR
spectra. The product shows a broad singlet at -27.30
ppm, which becomes a doublet with J PH ) 726 Hz
without proton irradiation. The large coupling constant
indicates the presence of a P-H bond: for example, HP-
(OC6H4NH)2 shows a doublet of triplets at -46.14 ppm

Metalated Hypervalent Phosphorus Compounds
Organometallics, Vol. 17, No. 16, 1998 3527
F igu r e 3. ORTEP drawing of 4 (50% probability el-
lipsoids), showing the numbering system. All hydrogen
atoms and the PF6 counterion are omitted for clarity.
F igu r e 1. ORTEP drawing of 1b (50% probability el-
lipsoids), showing the numbering system. All hydrogen
atoms are omitted for clarity.
-
For both metallaphosphoranes 1b and 2b, the five-
coordinate phosphorus adopts a trigonal-bipyramidal
(tbp) geometry with two oxygen atoms in the apical
positions and with the iron atom in one equatorial
position. The tbp geometry is slightly distorted: the two
apical bonds bend away from the iron fragment (the
Oap-P-Oap angle is 176.0° for 1b and 171.6° for 2b),
and in the equatorial plane, the angles of Fe-P-Neq
and Fe-P-Oeq (121.4-124.1°) are slightly greater than
the ideal angle (120°), though the sum of the equatorial
angles is 359.9° for 1b and 360.0° for 2b. The distortion
may arise from the apical-equatorial five-membered-
ring strain and/or a steric demand of the iron fragment.
The geometry around nitrogen (N1 and N2 for 1b and
N1 for 2b) is planar. The O1-P1-O2 bond is in the
same plane as the nitrogens and the three atoms
directly bonded to the nitrogens. Therefore, the nitro-
gen undergoes sp2 hybridization and the lone-pair
electrons are located on the equatorial plane, implying
π donation of the lone-pair electrons to equatorial σ*
orbitals on the phosphorus.19-22 The observed Fe-P
bond lengths (2.291 Å for 1b and 2.272 Å for 2b) are
close to that of the only precedent of iron phosphorane
(2.300 Å).6
The X-ray structure of HP(OC6H4O)(OC6H4NMe) was
reported by Holmes.23 Because this hydridophosphorane
corresponds to the nonmetalated version of 2b, the
comparison of these two structures should be informa-
tive when we consider the effect of a transition-metal
F igu r e 2. ORTEP drawing of 2b (50% probability el-
lipsoids), showing the numbering system. All hydrogen
atoms are omitted for clarity.
analyses, and the ORTEP drawings are displayed in
Figures 1, 2, and 3, respectively. The crystal data and
the selected bond lengths and angles are listed in Tables
3-6.
(19) Hoffmann, R.; Howell, J . M.; Muetterties, E. L. J . Am. Chem.
Soc. 1972, 94, 3047.
(20) Strich, A.; Veillard, A. J . Am. Chem. Soc. 1973, 95, 5574.
(21) McDowell, R. S.; Streitwieser, A., J r. J . Am. Chem. Soc. 1985,
107, 5849.
(22) (a) Wang, P.; Zhang, Y.; Glaser, R.; Reed, A. E.; Schleyer, P. v.
R.; Streitwieser, A. J . Am. Chem. Soc. 1991, 113, 55. (b) Wang, P.;
Zhang, Y.; Glaser, R.; Streitwieser, A.; Schleyer, P. v. R. J . Comput.
Chem. 1993, 14, 522.
(23) Clark, T. E.; Day, R. O.; Holmes, R. R. Inorg. Chem. 1979, 18,
1653.
These complexes have normal piano-stool configura-
tions; the iron has a cyclopentadienyl ligand bonded in
an η5 fashion, two terminal CO ligands, and a phospho-
rus ligand.

3528 Organometallics, Vol. 17, No. 16, 1998
Kubo et al.
Ta ble 3. Su m m a r y of Cr ysta l Da ta for 1b, 2b, a n d 4
1b
2b
4
formula
fw
C
21H19O4N2FeP
C20H16O5NFeP
437.17
C21H20O4N2F6FeP2
596.20
450.21
cryst syst
space group
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
monoclinic
P2/a
20.829(6)
7.280(3)
13.056(4)
triclinic
P1h
triclinic
P1h
9.963(3)
10.124(3)
10.495(4)
83.86(3)
61.87(3)
78.76(2)
915.5(5)
2
10.378 (6)
11.483 (5)
12.219 (5)
114.51 (3)
106.64 (4)
94.74 (4)
1235.1 (10)
2
91.39(2)
1979.2(10)
4
1.511
Z
D
calcd, g m-3
1.586
9.392
1.603
8.104
µ, cm-1
8.689
cryst size, mm
radiation (λ, Å)
scan technique
scan range, deg
no. of unique data
no. of unique data with Fo > 3σ(Fo)
Ra
0.48 × 0.30 × 0.20
Mo KR (0.710 73)
ω-2θ
0.38 × 0.35 × 0.25
Mo KR (0.710 73)
ω-2θ
0.43 × 0.33 × 0.25
Mo KR (0.710 73)
ω-2θ
3 < 2θ < 55
3 < 2θ < 55
3 < 2θ < 55
4554
3705
0.037
0.048
4210
3649
0.044
0.054
5411
4235
0.070
0.064
b
Rw
b
FA, FB
10.0, 0.00030
10.0, 0.00030
3.0, 0
R ) ∑||Fo| - |Fc||/∑|Fo|. Rw ) [∑w||Fo| - |Fc|| /∑w|Fo| ]1/2 and w ) exp(FA(sin2 θ)/λ2)/(σ2(Fo) + FBFo2).
a
b
2
2
Ta ble 4. Selected Bon d Len gth s (Å) a n d An gles
Ta ble 5. Selected Bon d Len gth s (Å) a n d An gles
(d eg) w ith Esd ’s in P a r en th eses for 2b
(d eg) w ith Esd ’s in P a r en th eses for 1b
Bond Lengths
Bond Lengths
Fe(1)-P(1)
Fe(1)-C(21)
P(1)-O(2)
2.291(1)
1.764(2)
1.757(1)
1.722(1)
1.355(2)
1.143(2)
1.462(2)
1.453(2)
1.397(2)
Fe(1)-C(20)
P(1)-O(1)
P(1)-N(1)
O(1)-C(6)
O(3)-C(20)
N(1)-C(11)
N(2)-C(17)
C(6)-C(11)
1.770(2)
1.774(1)
1.721(1)
1.352(2)
1.134(2)
1.392(2)
1.395(2)
1.396(2)
Fe(1)-P(1)
Fe(1)-C(20)
P(1)-O(2)
P(1)-N(1)
O(2)-C(12)
O(4)-C(19)
N(1)-C(17)
C(6)-C(11)
2.272(1)
1.775(1)
1.745(1)
1.703(1)
1.352(1)
1.139(2)
1.388(1)
1.388(1)
Fe(1)-C(19)
1.772(1)
1.799(1)
1.675(1)
1.344(1)
1.371(1)
1.129(1)
1.463(1)
1.403(1)
P(1)-O(1)
P(1)-O(3)
P(1)-N(2)
O(1)-C(6)
O(3)-C(11)
O(5)-C(20)
N(1)-C(18)
C(12)-C(17)
O(2)-C(12)
O(4)-C(21)
N(1)-C(18)
N(2)-C(19)
C(12)-C(17)
Bond Angles
Bond Angles
P(1)-Fe(1)-C(19)
C(19)-Fe(1)-C(20)
Fe(1)-P(1)-O(2)
Fe(1)-P(1)-N(1)
O(1)-P(1)-O(3)
O(2)-P(1)-O(3)
O(3)-P(1)-N(1)
P(1)-O(2)-C(12)
P(1)-N(1)-C(17)
C(17)-N(1)-C(18)
O(3)-C(11)-C(6)
N(1)-C(17)-C(12)
Fe(1)-C(20)-O(5)
89.5(1) P(1)-Fe(1)-C(20)
94.5(1) Fe(1)-P(1)-O(1)
95.7(1) Fe(1)-P(1)-O(3)
123.8(1) O(1)-P(1)-O(2)
88.3(1) O(1)-P(1)-N(1)
84.7(1) O(2)-P(1)-N(1)
114.8(1) P(1)-O(1)-C(6)
113.8(1) P(1)-O(3)-C(11)
114.5(1) P(1)-N(1)-C(18)
117.4(1) O(1)-C(6)-C(11)
92.0(1)
92.0(1)
121.4(1)
171.6(1)
90.1(1)
P(1)-Fe(1)-C(20)
C(20)-Fe(1)-C(21)
Fe(1)-P(1)-O(2)
Fe(1)-P(1)-N(2)
O(1)-P(1)-N(1)
O(2)-P(1)-N(1)
N(1)-P(1)-N(2)
P(1)-O(2)-C(12)
P(1)-N(1)-C(18)
P(1)-N(2)-C(17)
C(17)-N(2)-C(19)
N(1)-C(11)-C(6)
N(2)-C(17)-C(12)
Fe(1)-C(21)-O(4)
88.8(1) P(1)-Fe(1)-C(21)
93.4(1) Fe(1)-P(1)-O(1)
93.8(1) Fe(1)-P(1)-N(1)
122.1(1) O(1)-P(1)-O(2)
87.4(1) O(1)-P(1)-N(2)
90.3(1) O(2)-P(1)-N(2)
113.7(1) P(1)-O(1)-C(6)
113.3(1) P(1)-N(1)-C(11)
92.8(1)
90.1(1)
124.1(1)
176.0(1)
90.4(1)
87.6(1)
113.8(1)
114.7(1)
88.6(1)
111.7(1)
114.6(1)
127.9(1)
112.3(1)
127.5(1) C(11)-N(1)-C(18) 117.4(1)
113.7(1) P(1)-N(2)-C(19)
117.2(1) O(1)-C(6)-C(11)
127.9(1)
112.5(1)
112.4(1) O(2)-C(12)-C(17) 112.3(1)
110.8(1) Fe(1)-C(19)-O(4)
176.8(1)
178.3(1)
111.1(1) O(2)-C(12)-C(17) 112.3(1)
110.8(1) Fe(1)-C(20)-O(3)
178.8(2)
176.9(2)
should overlap with the HOMO orbital shown in Figure
4. This is the case observed in the X-ray structures of
1b and 2b.
fragment on a phosphorane. As we go from the hydri-
dophosphorane to the iron phosphorane (2b), although
every bond around the phosphorus is lengthened, the
remarkable elongation of P-Oap is notable (0.122 Å
elongation for two P-Oap bonds vs 0.070 Å elongation
for the P-Oeq and P-Neq bonds). It has been reported6,8
that the π-donating ability of a transition-metal sub-
stituent in an equatorial site of a phosphorane may be
responsible for apical bond elongation. In our cases of
1b and 2b, the orientation of the Cp(CO)2Fe fragment
strongly supports its π back-donation. According to the
calculation by Hoffmann,24 the HOMO of the Cp(CO)2-
Fe+ fragment has π symmetry, as illustrated in Figure
4. If a phosphorane fragment accepts π-electron density
into the σ* orbital of the P-Oap bond, the σ* orbital
It can be considered that the Fe-P bond in an iron
phosphorane complex consists of σ donation from P to
Fe and π back-donation from Fe to P. The substituents
on the phosphorus in 1b are two amino and two aryloxy
groups, whereas those in 2b are one amino and three
aryloxy groups. Therefore, supposing that the σ dona-
tion is a dominant factor concerning the Fe-P bond, the
bond would be shorter for 1b than for 2b, and op-
positely, if the π back-donation is dominant, the bond
would be shorter for 2b than for 1b. The X-ray analyses
revealed that the Fe-P bond is ca. 0.02 Å shorter for
2b than for 1b, indicating that the π back-donation is
more important in the Fe-P bond. This is also sup-
ported by the IR data. The νCO stretching bands of 2b
(2033 and 1985 cm-1) are at a higher frequency than
those of 1b (2024 and 1975 cm-1).
(24) Schilling, B. E. R.; Hoffmann, R.; Lichtenberger, D. L. J . Am.
Chem. Soc. 1979, 101, 585.

Metalated Hypervalent Phosphorus Compounds
Organometallics, Vol. 17, No. 16, 1998 3529
rangement is a Berry pseudorotation. Experimental
and theoretical investigations have been reported for
organophosphoranes, but little has been done for meta-
lated phosphoranes. Iron phosphorane complexes in
this study have two five-membered rings involving the
phosphorus, resulting in the creation of a chiral center
at the phosphorus in principle. Therefore, the polytopal
rearrangement corresponds to the racemization.
The 13C NMR spectra of 1a , 1b, 2a , and 2b at room
temperature exhibit two doublets in the CO region.
These observations indicate that the two carbonyl
ligands are diastereotopic; in other words, racemization
at the phosphorus does not occur on the NMR time
scale. The racemization was not observed even at 100
°C. In contrast, the 13C NMR spectrum for 3 shows one
doublet assignable to CO even at -50 °C, showing that
3 undergoes rapid racemization.
F igu r e 4. HOMO of the Cp(CO)2Fe fragment.
Ta ble 6. Selected Bon d Len gth s (Å) a n d An gles
(d eg) w ith Esd ’s in P a r en th eses for 4
Bond Lengths
Fe(1)-P(1)
Fe(1)-C(21)
P(1)-O(2)
2.161(1)
1.789(3)
1.625(2)
1.430(3)
1.143(3)
1.395(3)
1.365(3)
Fe(1)-C(20)
1.771(3)
1.602(2)
1.651(2)
1.405(3)
1.119(4)
1.462(3)
P(1)-O(1)
P(1)-N(2)
O(2)-C(12)
O(4)-C(21)
N(2)-C(19)
O(1)-C(6)
O(3)-C(20)
N(2)-C(17)
C(12)-C(17)
Bond Angles
It is highly likely that the racemization takes place
by Berry pseudorotation. Complexes 1a and 1b require
five transformation pathways, and 2a and 2b require
two pathways to complete the racemization. During the
interconversion, some tbp configurations have to have
an amino and/or an iron group in apical position(s),
though these groups prefer an equatorial position to an
apical position and, in addition, have to have a five-
membered chelate ring connecting two equatorial posi-
tions. Therefore, when the rings contain two different
atoms bonded to phosphorus, high-energy intermediates
are encountered during racemization by an intra-
molecular process. In contrast, the racemization of 3
is attained by only one transformation pathway, where
the iron fragment retains an equatorial position as a
pivotal group. This may be the reason for the fact that
3 racemizes even at -50 °C, whereas 1a ,b and 2a ,b do
not even at 100 °C.
Complexes 5-7 have two chiral centers at phosphorus
and iron, and so the formation of diastereomers is
expected. According to the 31P NMR spectra, two
diastereoisomers are separately detected at room tem-
perature. Therefore, it can be concluded that racem-
ization occurs at neither phosphorus nor iron for 5-7.
Sp ectr oscop ic F ea tu r es of Ir on P h osp h or a n es.
Let us examine the spectroscopic data which the iron
phosphoranes exhibit in this study. As one goes from
1 to 2 and 3, the number of amino substituents on the
phosphorus decreases. The νCO values in the IR spectra
increase in frequency in this order. This trend is
considered to be due to the decrease in σ-donicity and/
or the increase in π-acceptability of a phosphorane
fragment in this order.
P(1)-Fe(1)-C(20)
C(20)-Fe(1)-C(21)
Fe(1)-P(1)-O(2)
O(1)-P(1)-O(2)
O(2)-P(1)-N(2)
P(1)-O(2)-C(12)
P(1)-N(2)-C(17)
C(17)-N(2)-C(19)
N(2)-C(17)-C(12)
Fe(1)-C(21)-O(4)
88.5(1) P(1)-Fe(1)-C(21)
94.1(2) Fe(1)-P(1)-O(1)
111.3(1) Fe(1)-P(1)-N(2)
106.1(1) O(1)-P(1)-N(2)
93.5(1) P(1)-O(1)-C(6)
94.3(1)
112.6(1)
122.4(1)
108.4(1)
120.7(2)
111.3(2) C(11)-N(1)-C(18) 121.8(3)
112.2(2) P(1)-N(2)-C(19) 126.7(2)
121.0(2) O(2)-C(12)-C(17) 112.5(2)
110.3(2) Fe(1)-C(20)-O(3)
177.3(3)
176.5(3)
The X-ray structure of 4 (Figure 3) revealed that 4 is
a normal iron complex containing an amino-substituted
phosphite. It should be noted here that no transannular
interaction between N(1) and P(1) is observed. The
phosphorus atom adopts a distorted-tetrahedral geom-
etry, in which the O(2)-P(1)-N(2) angle is reduced to
93.5°, probably due to the five-membered ring. The
C(18)-N(1)-C(11) angle is 121.8°, and the C(18)-N(1)-
C(11)-C(10) torsion angle is 4.9°, indicating that N(1)
undergoes sp2 hybridization and the lone-pair electrons
are delocalized into the attached phenyl ring.
Rota tion a lon g th e F e-P (p h osp h or a n e) Bon d .
With phosphoranes, a π-electron-donating substituent
favors assuming an equatorial position. In an equato-
rial position, two types of π interactions are conceiv-
able: (i) π donation to the σ* orbital of an equatorial
bond and (ii) that of an apical bond. Theoretical
studies19-22 suggest that an amino group energetically
favors the type i interaction. In addition, in the cases
of 1b and 2b, the five-membered ring connecting apical
and equatorial positions sterically allows the amino
substituent to have only a type i interaction. The
restriction may make the iron fragment undergo a type
ii interaction in the solid state, although a transition-
metal fragment would basically favor the type i interac-
tion. Therefore, the difference between types i and ii
in energy with respect to the iron fragment is expected
to be small. In solution, the free rotation of the Fe-P
bond is deduced from NMR measurements. For ex-
ample, the 1H NMR spectrum of 1b showed only one
doublet due to NMe (Table 1). If 1b in solution retains
the structure observed in the solid state, the two NMe
groups should not be magnetically equivalent. The
Fe-P rotation did not cease even at -50 °C.
Comparison of νCO values of 1-3 with those of
Cp(CO)2FeX (X ) electron-withdrawing ligands) may
help the estimation of π-acidity of a phosphorane ligand.
Values of νCO for Cp(CO)2FeX are as follows: 2011, 1965
cm-1 (in CH2Cl2) for X ) Ph;26 2022, 1963 cm-1 (in CH2-
Cl2) for X ) C(O)Me;27 2040, 1990 cm-1 (in CH2Cl2) for
X ) P(O)(OMe)2;17 2053, 2003 cm-1 (Nujol mull) for X
) CF3.28 Therefore, it can be roughly said that the
(25) (a) Emsley, J .; Hall, D. In The Chemistry of Phosphorus: Harper
& Row: New York, 1976. (b) Holmes, R. R. In Pentacoordinated
Phosphorus; ACS Monograph Series 175 and 176; American Chemical
Society: Washington, DC, 1980; Vols. I and II.
(26) Gansow, O. A.; Schexnayder, D. A.; Kimura, B. Y. J . Am. Chem.
Soc. 1972, 94, 3406.
Rea r r a n gem en t a t P h osp h or a n e P h osp h or u s. It
is well-known for pentacoordinate phosphorus that
apical-equatorial rearrangement takes place readily.25
The widely accepted mechanism for the polytopal rear-
(27) Forschner, T. C.; Cutler, A. R. Organometallics 1985, 4, 1247.
(28) King, R. B.; Bisnette, M. B. J . Organomet. Chem. 1964, 2, 15.

3530 Organometallics, Vol. 17, No. 16, 1998
Kubo et al.
under vacuum. The residual dark red oil was washed repeat-
edly with a small amount of ether. Finally, a yellow powder
was formed, which was dried under reduced pressure to give
Cp(CO)2Fe{P(OC6H4NH)2} (1a ; 396 mg, 0.90 mmol, 56% yield).
Anal. Calcd for C19H15FeN2O4P: C, 54.06; H, 3.58; N, 6.64.
Found: C, 53.84; H, 3.38; N, 6.44. MS (EI, 70 eV; m/z (relative
acidity of a P(OC6H4Y)(OC6H4Z) ligand (Y, Z ) NH,
NMe, O) is greater than that of Ph or C(O)Me but less
than that of CF3 and is comparable to that of P(O)-
(OMe)2.
With 31P NMR data, the chemical shift moves upfield
on going from 3 to 2 and 1. This is parallel to the
increase in the number of electron-donating amino
groups. In a series of Cp(CO)LFe{P(OC6H4NH)2} com-
pounds where the ligand on the iron varies, the basicity
of L increases from 1a to 5, 6, and 7, which may cause
greater π back-donation of a Cp(CO)LFe fragment to the
phosphorus in this order. Thus, an upfield shift in the
31P NMR spectra is expected in this order. However,
the opposite tendency was observed. Although factors
affecting NMR chemical shifts are sometimes very
complicated, one plausible explanation which rational-
izes our observations is the following. The apical
intensity)): 422 (2, M+), 394 (10, M+ - CO), 366 (24, M+
-
2CO), 299 (100), 163 (59), 138 (49).
P r ep a r a t ion of [Cp (CO)2F e{P (OC6H 4NMe)(OC6H 4-
NHMe)}]P F 6 (4). A solution of o-HOC6H4NHMe (971 mg,
7.88 mmol) in THF (25 mL) was cooled to -78 °C, and then
n-BuLi (2.4 mL of a 1.60 M hexane solution, 3.84 mmol) was
added. After the cooling bath was removed, the mixture was
stirred for 20 min and then recooled to -78 °C. Then [Cp-
(CO)2Fe{P(OPh)3}]PF6 (2.28 g, 3.61 mmol) was added to the
solution. The reaction mixture was stirred at room temper-
ature overnight to give a homogeneous solution. The IR
spectrum of the solution showed two νCO absorption bands at
2024 and 1975 cm-1, indicating the formation of the metalla-
phosphorane Cp(CO)2Fe{P(OC6H4NMe)2}. After NH4PF6 (540
mg, 3.31 mmol) was added to the solution, the volatile
components were removed under vacuum. The residual yellow
oil was dissolved in ether, and the solution was stirred for a
few minutes to form a yellow precipitate. The supernatant
was decanted off, and the precipitate was dried in vacuo. After
addition of a small amount of acetone to the product, the
solution was filtered and the solvent was removed quickly
under reduced pressure. Finally, the yellow residue was
washed with ether until the supernatant became almost
colorless and was dried under vacuum to give [Cp(CO)2Fe-
{P(OC6H4NMe)(OC6H4NHMe)}]PF6 (4) as a yellow powder
(1.44 g, 2.41 mmol, 67% yield). Anal. Calcd for C21H20F6-
FeN2O4P2: C, 42.31; H, 3.38; N, 4.70. Found: C, 42.35; H,
3.18; N, 4.42. IR (cm-1; νCO, in acetone): 2076, 2033. 31P NMR
(δ, in acetone): 173.56 (quartet, J PH ) 10.2 Hz). 1H NMR (δ,
in acetone-d6): 2.82 (s, 3H, N(H)CH3), 3.42 (d, J PH ) 11.2 Hz,
3H, PNCH3), 4.72 (bs, 1H, NH), 5.87 (d, J PH ) 1.3 Hz, 5H,
C5H5), 6.34-7.19 (m, 8H, OC6H4N). 13C NMR (δ, in acetone-
d6): 29.06 (d, J PC ) 9.9 Hz, PNCH3), 30.37 (s, N(H)CH3), 89.40
O-P-O hypervalent 3c-4e bond is polarized as Oδ-
-
Pδ+-Oδ- intrinsically. Because the electron density on
the iron atom flows into the antibonding orbital of the
3c-4e bond, the π donation makes the 3c-4e bond
longer, which would cause an increase in the polariza-
tion. If so, the π back-donation accumulates a positive
charge on the phosphorus, leading to the downfield shift
in the 31P NMR.
Exp er im en ta l Section
Gen er a l P r oced u r es. All reactions and manipulations
were carried out under an atmosphere of dry nitrogen using
standard Schlenk techniques. Tetrahydrofuran and diethyl
ether were distilled from sodium benzophenone ketyl, and CH2-
Cl2 and CHCl3 were distilled from P2O5 and then stored under
dry nitrogen. Sodium amide, n-butyllithium (1.6 M in hexane),
acetone, triethylamine, catechol, and ammonium hexafluoro-
phosphate were obtained from common commercial sources
and used without further purification. N-methyl-o-aminophe-
nol29 and HP(OC6H4NH2)2 and Cp(CO)LFeCl (L ) P(OMe)3,
PMe3)30 were prepared according to the literature procedures.
Cp(CO){P(OPh)3}FeCl30 and [Cp(CO)2Fe{P(OPh)3}]PF6 and
(s, C5H5), 109.56 (d, J PC ) 6.3 Hz, OC6H4N), 112.15 (d, J PC
)
6.2 Hz, OC6H4N), 112.66 (d, J PC ) 1.9 Hz, OC6H4N), 116.99
(d, J PC ) 1.9 Hz, OC6H4N), 121.41 (d, J PC ) 3.7 Hz, OC6H4N),
121.43 (s, OC6H4N), 124.76 (s, OC6H4N), 128.12 (d, J PC ) 1.8
Hz, OC6H4N), 136.63 (d, J PC ) 5.6 Hz, OC6H4N), 139.47 (d,
J PC ) 14.3 Hz, OC6H4N), 141.97 (d, J PC ) 3.1 Hz, OC6H4N),
148.90 (d, J PC ) 10.0 Hz, OC6H4N), 207.38 (d, J PC ) 36.7 Hz,
CO), 207.63 (d, J PC ) 35.4 Hz, CO).
31
[Cp(CO)2Fe{P(OC6H4O)(OPh)}]PF6 were prepared by the
published methods with some modifications. NMR spectra
were recorded on J EOL LA-300, EX-400, and EX-270 spec-
trometers. 1H resonances were measured relative to residual
proton solvent peaks and referenced to TMS. 13C resonances
were measured relative to solvent peaks and referenced to
TMS. 31P resonances were measured relative to 85% H3PO4
as an external reference. Either a Shimadzu FTIR-8100A or
a FTIR-4000 spectrometer was used to obtain IR spectra. EI
mass spectra (70 eV) were recorded on a Shimadzu QP-2000
mass spectrometer. Elemental analysis data were obtained
on a Perkin-Elmer 2400 CHN elemental analyzer.
P r ep a r a tion of Cp (CO)2F e{P (OC6H4NH)2} (1a ). A solu-
tion of o-HOC6H4NH2 (351 mg, 3.22 mmol) in THF (10 mL)
was cooled to -78 °C, and then n-BuLi (1.1 mL of a 1.60 M
hexane solution, 1.76 mmol) was added. After the cooling bath
was removed, the mixture was stirred for 20 min. The solution
was added dropwise to the suspension of [Cp(CO)2Fe{P(OPh)3}]-
PF6 (1.02 g, 1.61 mmol) in THF (5 mL) at -78 °C. The reaction
mixture was stirred at room temperature overnight, which led
to a homogeneous solution. The solvents were removed under
reduced pressure, and the residue was extracted with ether
repeatedly until the ether solution became almost colorless.
The ether extract was collected, and the solvent was removed
P r ep a r a tion of Cp (CO)2F e{P (OC6H4NMe)2} (1b). [Cp-
(CO)2Fe{P(OC6H4NMe)(OC6H4NHMe)}]PF6 (4; 951 mg, 1.60
mmol) was suspended in THF (15 mL) and then NaNH2 (81
mg, 2.08 mmol) was added. While the mixture was stirred at
room temperature for a few minutes, the suspension of 1b
disappeared. After excess NaNH2 was filtered off, the solvent
was removed from the filtrate in vacuo to give a yellow oil,
and then the oil was dissolved in CHCl3 followed by filtration.
Finally, the solvent of the filtrate was removed under reduced
pressure, giving a yellow powder of Cp(CO)2Fe{P(OC6H4-
NMe)2} (1b; 628 mg, 1.39 mmol, 87% yield). Anal. Calcd for
C
21H19FeN2O4P: C, 56.03; H, 4.25; N, 6.22. Found: C, 55.79;
H, 4.16; N, 6.03. MS (EI, 70 eV; m/z (relative intensity)): 422
(1, M+ - CO), 394 (4, M+ - 2CO), 273 (46), 152 (100), 137
(11).
P r ep a r a tion of Cp (CO)2F e{P (OC6H4O)(OC6H4NH)} (2a )
a n d Cp (CO)2F e{P (OC6H4O)(OC6H4NMe)} (2b). A solution
of o-HOC6H4NH2 (60 mg, 0.55 mmol) in THF (2 mL) was cooled
to -78 °C, and then n-BuLi (0.28 mL of a 1.6 M hexane
solution, 0.45 mmol) was added. The solution was stirred at
room temperature for 20 min. The reaction mixture was added
to a THF solution (2 mL) of [Cp(CO)2Fe{P(OC6H4O)(OPh)}]-
PF6 (243 mg, 0.44 mmol) at -78 °C, and the solution was
warmed to room temperature. After the volatile components
(29) Anderson, G. W.; Bell, F. J . Chem. Soc. 1949, 2668.
(30) Kalck, P.; Poilblanc, R. C. R. Hebd. Seances Acad. Sci., Ser. C
1972, 274, 66.
(31) Catheline, D.; Astruc, D. Organometallics 1984, 3, 1094.

Metalated Hypervalent Phosphorus Compounds
Organometallics, Vol. 17, No. 16, 1998 3531
were removed under vacuum, the residue was dissolved in
ether followed by filtration. The solvent of the filtrate was
removed in vacuo, and the residue was washed with a small
amount of ether until the color of the supernatant changed
from dark red to yellow. Finally, the remaining yellow powder
was dried under reduced pressure to give Cp(CO)2Fe-
{P(OC6H4O)(OC6H4NH)} (2a ; 132 mg, 0.31 mmol, 87% yield).
Anal. Calcd for C19H14FeNO5P: C, 53.93; H, 3.33; N, 3.31.
Found: C, 53.44; H, 3.33; N, 3.15. MS (EI, 70 eV; m/z (relative
dissolved in THF (10 mL), NaNH2 (111 mg, 2.85 mmol) was
added, and the mixture was stirred overnight at room tem-
perature. The volatile components were removed in vacuo,
and the product was extracted with ether. The solvent was
removed under reduced pressure, and the product was then
extracted with ether/pentane (1/1). Finally, the solvents were
removed under reduced pressure to give a yellow powder of 7
(228 mg, 0.49 mmol, 24% yield). Complex 7 also consists of a
pair of diastereomers in the ratio of ca. 1:1.2. IR (cm-1, in
THF): νCO 1942. 1H NMR (δ, in C6D6): 1.04 (d, J PH ) 9.7 Hz,
9H, PCH3), 4.19 (m, 5H, C5H5), 4.62 (d, J PH ) 13.7 Hz, 2H,
NH), 6.44-6.91 (m, 8H, OC6H4N), 0.87 (d, J PH ) 9.6 Hz, 9H,
PCH3), 4.23 (m, 5H, C5H5), 4.79 (d, J PH ) 13.7 Hz, 2H, NH),
6.30-6.91 (m, 8H, OC6H4N). 31P NMR (δ, in THF): 38.11 (d,
J PP ) 104.6 Hz, P(III)), 42.73 (dt, J PP ) 104.6 Hz, J PH ) 15.8
intensity)): 423 (1, M+), 395 (11, M+ - CO), 367 (58, M+
-
2CO), 258 (24), 230 (75), 164 (41), 138 (100), 121 (34).
Under similar conditions, Cp(CO)2Fe{P(OC6H4O)(OC6H4-
NMe)} (2b) was obtained as a yellow powder (47% yield).
Anal. Calcd for C20H16FeNO5P: C, 54.95; H, 3.69; N, 3.20.
Found: C, 55.07; H, 3.57; N,3.06. MS (EI, 70 eV; m/z (relative
intensity)): 409 (4, M+ - CO), 381 (16, M+ - 2CO), 152 (100),
137 (11).
P r ep a r a tion of Cp (CO)2F e{P (OC6H4O)2} (3). To a sus-
pension of [Cp(CO)2Fe{P(OPh)3}]PF6 (989 mg, 1.56 mmol) were
added o-HOC6H4OH (350 mg, 3.18 mmol) and NEt3 (0.44 mL,
3.16 mmol); the solution was then stirred at room temperature
overnight. Volatile components were removed under vacuum,
and the residue was extracted with ether followed by filtration.
The solvent of the filtrate was removed under reduced pres-
sure. After the extraction was repeated again, the residue was
washed with a small amount of ether until the color of the
supernatant changed from deep purple to yellow and was then
dried under vacuum to give a yellow powder of Cp(CO)2Fe-
Hz, P(V)), 37.78 (d, J PP ) 104.6 Hz, P(III)), 39.41 (dt, J PP
)
104.6 Hz, J PH ) 15.2 Hz, P(V)). 13C NMR (δ, in C6D6): 19.91
(d, J CP ) 29.2 Hz, PCH3), 20.42 (d, J CP ) 29.2 Hz, PCH3), 83.09
(s, C5H5), 83.15 (s, C5H5), 108.49 (s, OC6H4N), 108.65 (s,
OC6H4N), 108.67 (d, J CP ) 10.5 Hz, OC6H4N), 108.87 (d, J CP
) 10.0 Hz, OC6H4N), 118.25 (s, OC6H4N), 118.42 (s, OC6H4N),
118.92 (s, OC6H4N), 119.05 (s, OC6H4N), 133.96 (d, J CP ) 6.2
Hz, OC6H4N), 134.03 (d, J CP ) 4.4 Hz, OC6H4N), 151.00 (d,
J CP ) 6.2 Hz, OC6H4N), 151.16 (d, J CP ) 8.1 Hz, OC6H4N),
217.03 (dd, J CP ) 34.2, 50.4 Hz, CO), 219.02 (dd, J CP ) 34.5,
50.0 Hz, CO). MS (EI, 70 eV; m/z (relative intensity)): 470
(5, M+), 442 (17, M+ - CO), 229 (100), 197 (84), 163 (59), 137
(80), 109 (92), 61 (83), 59 (60).
X-r a y Str u ctu r e Deter m in a tion s. Suitable crystals of 1b
and 2b were obtained through recrystallization from hot
toluene, and that of 4 was obtained similarly from hot 1,2-
dichloroethane. The crystals were mounted on a Mac Science
MXCκ diffractometer and irradiated with graphite-monochro-
mated Mo KR radiation (λ ) 0.710 73 Å). Unit-cell dimensions
were obtained by least squares from the angular settings of
29 accurately centered reflections with 31° < 2θ < 35° for 1b
and 2b and from that of 20 such reflections with 32° < 2θ <
35° for 4. P2/a, P1h, and P1h were selected as the space groups
for 1b, 2b, and 4, respectively, which led to successful
refinements. Reflection intensities were collected in the usual
manner at 25 °C, and 3 reflections checked after every 200
reflections showed no decrease in intensity.
The structures were solved by a direct method with the
program SIR92.32 The positions of hydrogen atoms were
determined from subsequent difference Fourier maps for 1b
and 2b, and those for 4 were calculated by assuming idealized
geometries. For 4, the counteranion, PF6-, was refined as a
disordered molecule. Absorption and extinction corrections
were then applied, and several cycles of a full-matrix least-
squares refinement with anisotropic temperature factors for
{P(OC6H4O)2} (3; 441 mg, 66% yield). Anal. Calcd for C19H13
-
FeO6P: C, 53.81; H, 3.09. Found: C, 53.82; H, 3.18. MS (EI,
70 eV; m/z (relative intensity)): 424 (2, M+), 396 (8, M+ - CO),
368 (100, M+ - 2CO), 303 (23), 229 (23), 139 (94), 121 (33).
P r epar ation of Cp(CO)LFe{P (OC6H4NH)2} (L ) P (OP h )3
(5), P (OMe)3 (6)). Cp(CO){P(OPh)3}FeCl (270 mg, 0.55 mmol)
was treated with the reaction mixture of HP(OC6H4NH)2 (134
mg, 0.54 mmol) and n-BuLi (0.5 mL of a 1.6 M hexane solution,
0.80 mmol) in THF (5 mL) at -78 °C. The reaction mixture
was then stirred at room temperature overnight. Although
the formation of the metallaphosphorane Cp(CO){P(OPh)3}-
Fe{P(OC6H4NH)2} (5) was confirmed by the 31P NMR spec-
trum, the product could not be isolated in a pure form, because
unknown byproducts and the unreacted starting materials
were not removed. Complex 6 was prepared under similar
conditions.
P r ep a r a tion of Cp (CO)(P Me3)F e{P (OC6H4NH)2} (7).
Cp(CO)(PMe3)FeCl (535 mg, 2.05 mmol) was treated with the
reaction mixture of HP(OC6H4NH)2 (491 mg, 1.99 mmol) and
n-BuLi (1.5 mL of a 1.6 M hexane solution, 2.4 mmol) in THF
(10 mL) at -78 °C, and the solution was stirred at room
temperature overnight. After NH4PF6 (500 mg, 3.07 mmol)
was added to the solution, the volatile components were
removed under reduced pressure. The residual reddish oil was
washed with ether until the supernatant became almost
colorless and was dried in vacuo. The product is a pair of
diastereomers of[Cp(CO)(PMe3)Fe{P(OC6H4NH)(OC6H4NH2)}]-
PF6, according to its spectroscopic data. IR (cm-1, in THF):
non-hydrogen atoms led to final values of R ) 0.037 and Rw
)
0.048 for 1b, R ) 0.044 and Rw ) 0.054 for 2b, and R ) 0.070
and Rw ) 0.064 for 4. All calculations were performed on an
SGI Indy R5000 computer using the program system CRYS-
TAN-GM33 with neutral atom scattering factors from Cromer
and Waber.34
ν
CO 1985. 31P NMR (δ, in THF): 31.97 (d, J PP ) 85.2 Hz), 32.14
Ack n ow led gm en t. This work was supported by a
Grant-in-Aid for Scientific Research (No. 07404037) and
a Grant-in-Aid on Priority Area of Interelement Chem-
istry (No. 09239235) from the Ministry of Education,
Science, Sports and Culture of J apan.
(d, J PP ) 88.8 Hz), 179.46 (dd, J PP ) 88.8 Hz, J PH ) 28.6 Hz),
182.40 (dd, J PP ) 86.4 Hz, J PH ) 29.2 Hz). The product was
(32) Altomare, A.; Burla, M. C.; Camalli, M.; Cascarano, M.;
Giacovazzo, C.; Guagliardi, A.; Polidori, G. J . Appl. Crystallogr. 1994,
27, 435.
(33) A package for cystal structure analysis from Mac Science Co.
Ltd., c/o Sodick Co. Ltd., Nakamachidai 3-12-1, Tsuzuki-ku, Yokohama
224, J apan.
(34) Cromer, D. T.; Waber, J . T. In International Tables for X-ray
Crystallography; Kynoch Press: Birmingham, England, 1974; Vol. IV,
Table 2.2A.
Su p p or tin g In for m a tion Ava ila ble: Tables giving posi-
tional and thermal parameters and bond distances and angles
for 1b, 2b, and 4 (17 pages). Ordering information is given
on any current masthead page.
OM980384Q