Reactivities of secondary phosphine selenides Cp(CO)2FeP(Se)(OR) 2: Formation of a diiodine charge transfer adduct and se-methylation

Article abstract of DOI:10.1021/om900508b

The organoiron-substituted phosphine selenides Cp(CO)₂FeP(Se) (OR)₂ (R = ⁱPr (1a), ⁿPr (1b), Et (1c)) were synthesized. The metalloligands, capable of reacting as nucleophiles toward Me₃OBF₄

Full text of DOI:10.1021/om900508b

4
958 Organometallics 2009, 28, 4958–4963
DOI: 10.1021/om900508b
Reactivities of Secondary Phosphine Selenides Cp(CO) FeP(Se)(OR) :
2
2
Formation of a Diiodine Charge Transfer Adduct and Se-Methylation
†
Ling-Song Chiou, Ching-Shiang Fang, Bijay Sarkar, Ling-Kang Liu, Max K. Leong,*
†
†
‡
,†
,†
and C. W. Liu*
†
‡
Department of Chemistry, National Dong Hwa University, Hualien, Taiwan 97401, and Institute of
Chemistry, Academia Sinica, Taipei, Taiwan
Received June 15, 2009
i
The organoiron-substituted phosphine selenides Cp(CO) FeP(Se)(OR) (R= Pr (1a), Pr (1b), Et
n
2
2
(
1c)) were synthesized. The metalloligands, capable of reacting as nucleophiles toward Me OBF ,
3 4
formed Se-methylated products (2a-c). Upon reaction with diiodine, they formed spokelike charge-
transfer adducts (3a-c). Among them 1b, 2b, and 3a were structurally authenticated, and 3a was the
first structurally characterized, charge-transfer spoke adduct of a secondary phosphine selenide with
diiodine.
2
,5
Since Zingaro and Meyers reported their spectroscopic
studies confirming the formation of 1:1 adducts of tertiary
known are spokelike. Although a search in the Cambridge
Structure Database results in several CT adducts of tertiary
1,6
phosphine sulfide with dihalogens and interhalogens,
1
phosphine selenides (R PdSe) with diiodine in 1962, sur-
3
prisingly there was no further progress on this chemistry
until Godfrey reported the solid-state structures of R PSeI
there has been no report of a CT adduct involving a
7
secondary phosphine chalcogenide with halogens or inter-
3
2
2
in 1997. It was found that phosphine selenides can donate
halogens until now. On the other hand, a few reports on
Se-glycosylations with the formation of a PSe-C bond by
the nucleophilic attack of a phosphoroselenium unit on
electron density toward the σ* antibonding orbital of di-
iodine to form a charge-transfer (CT) adduct, as confirmed by
3
8
single-crystal X-ray crystallography, since d(I-I) values in
glycosyl bromide/anhydride or via isomerization of a
9
P(dSe)C unit are known, which are important due to their
these adducts are elongated compared to that in I in
2
4a
4b
10
the solid state. Godfrey and du Mont also reported a few
T-shaped charge-transfer adducts with dibromine. In contrast,
all the tertiary phosphine selenide-diiodine 1:1 CT adducts
potential biological activities.
that recently this group has reported that the organoiron
It should be noted
i
phosphoroselenide [Cp(CO) Fe(O Pr) PSe], which contains
P(O Pr) Se] , a conjugate base of the typical secondary
2
2
2
i
-
[
*
To whom correspondence should be addressed. E-mail: chenwei@
phosphine selenide R P(H)Se, allows P to retain the þ3
2
mail.ndhu.edu.tw. Fax: þ886-3-8633570.
formal oxidation number and displays a longer P-Se bond
upon metal complexation, characteristic for a secondary
(1) Zingaro, R. A.; Meyers, E. A. Inorg. Chem. 1962, 1, 771.
(2) Godfrey, S. M.; Jackson, S. L.; McAuliffe, C. A.; Pritchard, R. G.
1
phosphine chalcogenide. Herein, we report the synthesis
1a
J. Chem. Soc., Dalton Trans. 1997, 4499.
3) Lippolis, V.; Isaia, F. Charge-Transfer (C.-T.) Adducts and
(
of the metalloligands Cp(CO) Fe(OR) PSe (1a-c) along
2
2
Related Compounds. In Handbook of Chalcogen Chemistry-New Per-
spectives in Sulfur, Selenium and Tellurium; Devillanova, F. A., Ed.; Royal
Society of Chemistry: Cambridge, U.K., 2006.
with the first report of a diiodine charge-transfer adduct of
a secondary phosphine selenide, Cp(CO) Fe(OR) PSeI
2
2
2
(
4) (a) Godfrey, S. M.; Jackson, S. L.; McAuliffe, C. A.; Pritchard,
(3a-c). Also described is the reaction of the metalloligand
R. G. J. Chem. Soc., Dalton Trans. 1998, 4201. (b) Hrib, C. G.; Ruthe, F.;
Sepp €a l €a , E.; B €a tcher, M.; Druckenbrodt, C; Wismach, C.; Jones, P. G.;
du Mont, W.-W.; Lippolis, V.; Devillanova, F. A.; B €u hl, M. Eur. J. Inorg.
Chem. 2006, 88.
(7) (a) Walther, B. Coord. Chem. Rev. 1984, 60, 67. (b) Davies, R.
Chalcogen-Phosphorus (and Heavier Congeners) Chemistry. In Handbook
of Chalcogen Chemistry-New Perspectives in Sulfur, Selenium and Tell-
urium; Devillanova, F. A., Ed.; Royal Society of Chemistry: Cambridge,
U.K., 2006.
(5) (a) Barnes, N. A.; Godfrey, S. M.; Halton, R. T. A.; Khan, R. Z.;
Jackson, S. L.; Pritchard, R. G. Polyhedron 2007, 26, 4294. (b) Hursthouse,
M. B.; Hibbs, D. E.; Bricklebank, N. Deposited in Cambridge Structural Database
(
CCDC deposition No. 217903), 2003. (c) Jeske, J.; du Mont, W.-W.; Jones, P. G.
(8) (a) Michalska, M.; Orlich-Krezel, I.; Michalski, J. Tetrahedron
1978, 34, 2821. (b) Borowiecka, J. Heteroat. Chem. 2000, 11, 292.
(c) Misiura, K.; Szymanowicz, D.; Stec, W. J. Collect. Czech. Chem.
Commun. 1996, 61, S101. (d) Michalska, M.; Michalski, J.; Orlich-Krezel,
I. Pol. J. Chem. 1979, 53, 253. (e) Lipka, P.; Michalska, M. Carbohydr. Res.
1983, 113, 317. (f ) Kudelska, W. Heteroat. Chem. 1999, 10, 259.
(9) Rachon, J.; Cholewinski, G.; Witt, D. Chem. Commun. 2005, 2692.
(10) (a) Wo ꢀz niak, L. A.; Sochacki, M.; Mitsuya, H.; Kageyama, S.;
Stec, W. J. Bioorg. Med. Chem. Lett. 1994, 4, 1033. (b) Xu, Y.; Kool, E. T.
J. Am. Chem. Soc. 2000, 122, 9040.
(11) (a) Sarkar, B.; Wen, S.-Y.; Wang, J.-H.; Chiou, L.-S.; Santra,
B. K.; Liao, P.-K.; Wang, J.-C.; Liu, C. W. Inorg. Chem. 2009, 48, 5129.
(b) Liu, C. W.; Chen, J.-M.; Santra, B. K.; Wen, S.-Y.; Liaw, B.-J.; Wang, J.-C.
Inorg. Chem. 2006, 45, 8820. (c) Santra, B. K.; Chen, C.-L.; Sarkar, B.; Liu,
C. W. Dalton Trans. 2008, 2270.
Chem. Eur. J. 1999, 5, 385. (d) Jones, P. G.; Jeske, J. Deposited in Cambridge
Structural Database (CCDC deposition No. 239393), 2004. (e) Boyle, P. D.;
Godfrey, S. M. Coord. Chem. Rev. 2001, 223, 265. (f ) du Mont, W.-W.; B €a tcher,
M.; Daniliuc, C.; Devillanova, F. A.; Druckenbrodt, C.; Jeske, J.; Jones, P. G.;
Lippolis, V.; Ruthe, F.; Sepp €a l €a , E Eur. J. Inorg. Chem. 2008, 4562.
(6) (a) Cross, W. I.; Godfrey, S. M.; Jackson, S. L.; McAuliffe, C. A.;
Pritchard, R. G. J. Chem. Soc., Dalton Trans. 1999, 2225. (b) Arca, M.;
Devillanova, F. A.; Garau, A.; Isaia, F.; Lippolis, V.; Verani, G.; Demartin, F.
Z. Anorg. Allg. Chem. 1998, 624, 745. (c) Bransford, J. W.; Meyers, E. A.
Cryst. Struct. Commun. 1978, 7, 697. (d) Apperley, D. C.; Bricklebank, N.;
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2
003, 398. (f ) Bricklebank, N.; Coles, S. J.; Forder, S. D.; Hursthouse, M. B.;
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pubs.acs.org/Organometallics
Published on Web 08/19/2009
r 2009 American Chemical Society

Article
Organometallics, Vol. 28, No. 17, 2009 4959
Scheme 1
a
Cp(CO) Fe(OR) PSe as a nucleophile to form the selenium-
2
Table 1. Hydrogen-Bonding Parameters for 1a,b and 3a
2
methylated products 2a-c. The structure of 1a and the
synthesis of 2a were reported earlier.
sym operation
for A
1
1b
˚
A/A
˚
D-H
3 3 A
H
D
A/A D-H A/deg
3 3 3
3
3 3 3
3 3 3
Compound 1a
Results and Discussion
C21-H21A Se1 2.987(0) 3.700(4) 131
3 3
1 þ x, y, z
1 þ x, y, z
3
The secondary phosphine selenide metalloligands Cp-
C35-H35A Se2 2.921(0) 3.686(4) 136
3
3 3
i
n
CO) FeP(Se)(OR) (R= Pr (1a), Pr (1b), Et (1c)) could
(
be obtained by refluxing NH [(OR) PSe ] with Cp Fe -
2 2
Compound 1b
4
2
2
2
2
C11-H11
3 3 3 Se1
3.096(1) 3.791(9) 129
x, -1 þ y, z
-1 þ x, y, z
(
CO) for 4 h in toluene and purified by column chroma-
4
Compound 3a
tography over silica gel using 10% ethyl acetate in hexane.
These metalloligands Cp(CO) FeP(Se)(OR) are stable
enough to store due to their P coordination to the
2
2
C3-H3
3 3 Se1
3.008(2) 3.740(7) 132
˚
3
a
D-H lengths are 0.98 A for all of the cases.
iron-carbonyl (Fp=Cp(CO) Fe) fragment and have been
2
successfully utilized to build heterometallic clusters con-
1
1a,c
taining Cu(I), Ag(I), Cd(II), and Hg(II).
Simple stirring
of Cp(CO) FeP(Se)(OR) with an equimolar amount of
2
2
Me OBF in CH Cl at room temperature results in the
3
4
2
2
formation of [Cp(CO) FeP(SeCH )(OR) ](BF ) (R =
4
2
3
2
i
n
Pr (2a), Pr (2b), Et (2c)), and stirring with I at 0 ꢀC in
2
DCM yields the charge-transfer adducts Cp(CO) FeP-
(
2
i
n
OR) SeI (R= Pr (3a), Pr (3b), Et (3c)) (Scheme 1). All the
2 2
compounds have been characterized by spectroscopy
multinuclear NMR, IR) and microanalyses. Isolation of
single crystals suitable for X-ray crystallography enabled us
(
to interpret the structures of 1a,b, 2b, and 3a.
Crystallography. The n-propyl derivative [Cp(CO) FeP-
2
n
˚
(
Se)(O Pr) ] (1b) exhibits the P-Se (2.117(2) A) bond lengths
2
similar to those in its isopropyl homologue 1a, which was
1
1b
reported earlier. The C-H Se type of H-bonding ob-
3
3 3
served in the lattice forms a 1D chain (C-H Se bonding is
3 3
3
shown in Figure S1 (Supporting Information)), with the
Se distances being in the range of reported values for
H
this type of interaction (parameters are given in Table 1).
3
3 3
1
2
Figure 1. Perspective view of the cation in 2b. Selected bond
˚
On the other hand, the solid-state structure of 2b (Figure 1)
˚
lengths (A) and angles (deg): Fe(1)-C(13)=1.774(9), Fe(1)-C-
exhibits a shorter Fe-P distance (2.178(2) A) and a longer
(12)=1.778(9), Fe(1)-P(1)=2.178(2), Se(1)-C(101)=1.975(11),
Se(1)-P(1)=2.232(2); C(101)-Se(1)-P(1)=98.6(4), Fe(1)-P-
(1)-Se(1)=110.86(10), O(3)-C(12)-Fe(1)=179.0(8), O(4)-C-
(13)-Fe(1)=177.1(8).
˚
P-Se length (2.232(2) A) compared to those observed in 1b.
˚
The Se-C length (1.975(11) A) is comparable to those
1
reported in Me C(CH O) P(Se)SeCH (1.951(4) A). The
4
˚
2
2
2
3
angles around P are in the range 93.7(3)-118.9(3)ꢀ, with the
O-P-O angle being the smallest.
longer than that in free metalloligand 1a, its precursor, but is
slightly shorter than that in Se-methylated 2b. In fact, it is still
slightly shorter than a typical P-Se single bond: e.g., as in
i
The structural elucidation of Cp(CO) FeP(O Pr) SeI (3a)
2
2
2
exhibits a spokelike charge-transfer adduct of diiodine on the
organoiron-substituted phosphine selenide, [Cp(CO) FeP-
16
˚
˚
P Se (2.24(1) A). Also, the Fe-P length, at 2.1871(13) A,
4
3
2
lies between those observed in 1a,b and 2b. The I-I distance,
i
˚
˚
(
Se)(O Pr) ]. The P-Se distance in 3a, 2.2080(12) A, is ∼0.08 A
2
˚ ˚
.9742(5) A, which is comparable to 2.985(2) A in (Et N) -
2 3
2
2
PSeI , with the longest I-I distance for a charge-transfer
2
(12) (a) Iwaoka, M.; Tomoda, S. J. Am. Chem. Soc. 1994, 116, 4463.
compound reported to date, indicates that a very strong
charge-transfer adduct has been formed, whereas that distance
(
b) Salon, J.; Sheng, J.; Jiang, J.; Chen, G.; Caton-Williams, J.; Huang, Z.
J. Am. Chem. Soc. 2007, 129, 4862. (c) Narayanan, S. J.; Sridevi, B.;
Chandrashekar, T. K.; Vij, A.; Roy, R. Angew. Chem., Int. Ed. 1998, 37,
2
˚
in Ph PSeI is only 2.881(2) A. The I-Se bond length,
3
2
3
394.
13) Liu, C. W.; Shang, I.-J.; Hung, C.-M.; Wang, J.-C.; Keng, T.-C.
Dalton Trans. 2002, 1974.
14) Bartczak, T. J.; Wolf, W.; Swepston, P. N.; Zerong, L. Acta
Crystallogr., Sect. C: Cryst. Struct. Commun. 1987, 43, 1788.
(
(15) Sarkar, B.; Fang, C.-S.; You, L.-Y.; Wang, J.-C.; Liu, C. W. New
J. Chem. 2009, 33, 626.
(16) Keulen, E.; Vos, A. Acta Crystallogr. 1959, 12, 323.
(

4
960 Organometallics, Vol. 28, No. 17, 2009
Chiou et al.
Figure 3. Predicted infrared spectrum of 3a. The absorption
peaks are theoretically expected to originate from Se-I-I
-
1
-1
stretching at 151 cm , from P-Se stretching at 511 cm
,
-
1
.
and from C-O vibrations at 2033 and 2003 cm
reminiscent of the 83.7 ppm downfield shift for 1a compared
i
to [NH (O Pr) PSe ].
11b,13
4
2
2
The formation of an Se-C bond leading to a decrease in
the P-Se bond order, as expected in compounds 2b,c, is also
confirmed from the lowering of coupling constants observed
3
1
1
77
in both P NMR ( J = 437.5 and 438.7 Hz) and Se
SeP
1
NMR ( J =438.1 and 438.1) spectra for 2b,c, respectively,
SeP
11b
compared to their precursor 1b,c, which is also true for 2a.
1
A similar value of J (480.7 Hz) was observed for the P-Se
PSe
i
single bond in the [( PrO) PSe CH ] CH reported from this
2
2
2 2
2
1
group. The coupling of SeCH protons with P ( JPH) in 2b
5
3
3
Figure 2. (a) Perspective view of 3a. (b) C-H Se observed in the
3 3
1
(11.88 Hz) and 2c (11.94 Hz) in the H NMR spectra also
3
˚
lattice of 3a. Bond lengths (A) and angles (deg): I(1)-Se(1)=2.7196-
6), I(1)-I(2) = 2.9742(5), Se(1)-P(1)=2.2080(12), Fe(1)-C(6)=
.772(5), Fe(1)-C(7) = 1.778(5), Fe(1)-P(1) = 2.1871(13);
Se(1)-I(1)-I(2) =172.272(17), P(1)-Se(1)-I(1) =102.36(3), Fe-
confirms the Se-methylation. It is worth noting that the
-
(
1
precursor diselenophosphates [(OR) PSe ] can act as nu-
2
2
cleophiles and one of the two Se atoms can be alkylated by
1
5
the reaction with alkyl halide. During the formation of
metalloligands 1a-c, the Fp unit gets connected to the
diselenophosphate with the loss of one Se atom. The remain-
ing Se atom in each of the metalloligands (1a-c) still retains
its nucleophilic character to form a Se-methylated product.
(
1)-P(1)-Se(1) = 119.30(5), O(2)-C(7)-Fe(1) = 177.9(5), O-
1)-C(6)-Fe(1)=178.7(5).
(
˚ ˚
.7196(6) A, is also comparable with 2.715(2) A in (Et N) -
2 3
2
PSeI . An approximately tetrahedral angle around the sele-
2
3
1
nium atom is observed, P-Se-I = 102.36(3)ꢀ, which is ex-
pected for a CT adduct. A slight deviation from an ideal
The P NMR spectrum of 3a displays a singlet peak
shifted about 4.3 ppm downfield from that of its precursor
1a, which again supports the assertion that the charge-
transfer complex 3a contains a significant P-Se double-
bond character, since the perturbation of the phosphorus
2
tetrahedral angle can probably be explained by (1) the reten-
tion of P-Se double-bond character and (2) valence shell
2
electron pair repulsion. The Se-I-I linkage is essentially
linear (172.272(17)ꢀ), which is common in structurally
characterized charge-transfer complexes of diiodine. The
atom in 1a is relatively small upon coordination of Se to
1
2,5
diiodine. However, a decrease in J (∼180 Hz) compared
PSe
compound 3a also exhibits the C-H Se type of H-bonding
to its precursor (1a) confirms the lengthening of the P-Se
bond and signifies the formation of a strong charge-transfer
adduct. A similar observation is true for compounds 3b,c. It
3
3 3
in its lattice, as shown in Figure 2b (parameters listed in
Table 1).
7
7
It should be noted that the methylated Se atom in 2b is in
an apparent anti orientation with respect to the Cp ring,
whereas the Se atoms in 1a,b and 3a are in an approximately
syn orientation. An estimation of this difference can be
expressed by the Se-P-Fe-C* torsion angles (C* = cen-
troid of the Cp ring), which are -57.94(11), -176.74(7), and
should be noted that we could not observe the Se resonance
frequency of the charge-transfer products (3a-c), even with
a concentrated solution, for reasons which cannot be well
understood.
IR and Theoretical Calculation on the CT Adduct 3a. An
attempt to acquire the Raman spectra of the CT spoke
adduct, which could be useful to identify ν(I-I) stretching
modes and distinguish the different types of adducts, also
failed due to the decomposition of the adduct under the laser
beam. Thus, an FT-IR spectrum of 3a was generated by DFT
calculations (Figure 3). Accordingly, two strong bands at
-
50.27(8)ꢀ for 1b, 2b and 3a, respectively. The torsion angles
of Se-P-Fe-C* in two independent molecules in the
asymmetric unit of 1a are 64.56(6) and 54.18(7)ꢀ. Therefore,
the observed difference in spatial arrangement of the Se atom
relative to the Cp ring in 1a,b, 3a, and 2b is presumably due to
-
1
the absence of the C-H
the lattice of the latter.
3 3 Se type of hydrogen bonding in
2003 and 2033 cm , which are the typical symmetric and
asymmetric stretching modes of two carbonyl groups con-
nected to the iron(II) center, match well with the experi-
3
NMR. The compounds 1b,c exhibit a singlet with a pair of
1
3
77
-1
Se satellites with P- Se coupling constants of 718.2 and
mental values of 2009 and 2054 cm . In addition, the
-1
3
20.5 Hz, respectively, in the P NMR spectrum and a
1
7
doublet peak ( J = 718.9 and 717.5 Hz, respectively) in
ν(PdSe) band of the free metalloligand (538 cm ) is shifted
to lower energy at 519 cm (511 cm by computation) in
1
-1
-1
SeP
7
the Se NMR spectrum; these are very similar to those in
7
the case of CT adduct 3a, indicating the lengthening of the
-1
11b
1
a
and are suggestive of a typical P-Se double bond,
P-Se bond. Thus, the band at 151 cm , which is lower than
-
1
that of free I (180 cm in the solid and 181 cm by
-1
which is supported by the crystallographic P-Se lengths.
On the other hand, an ∼84.7 ppm downfield shift observed
2
calculation), displayed in Figure 3 can be reasonably as-
signed as the ν(Se-I-I) vibration.
1
3
31
for 1c compared to [NH (OEt) PSe ] in P NMR, is
4
2
2

Article
Organometallics, Vol. 28, No. 17, 2009 4961
Table 2. Experimental and Calculated Structure Parameters and
on the diiodine moiety in 3a are more negative than that in
the free diiodine molecule. Furthermore, the bond distances
between both iodine atoms in the optimized 3a molecule and
i
Atomic Charges of 3a and the Model Compound [P(O Pr) SeI ] (X)
a
3
2
3
a
˚
free optimized diiodine molecule are 3.024 and 2.863 A,
˚
X
calcd
respectively, indicating a 0.161 A increase in I-I bond
length. A similar observation can also be found in the crystal
exptl
calcd
˚
Bond Lengths
2.2080(12)
1.573(3)
1.580(3)
structure, in which the I-I distance in 3a is 2.974 A, as
1
9
˚
compared with 2.772 A in free I .
2
P-Se
P-O
P-O
P-O
P-Fe
Se-I
I-I
2.349
1.729
1.729
2.305
1.695
1.689
1.687
Furthermore, the NBO analysis showed that the I-Se
bond order is 0.291, suggesting a weak bond formation
between Se and I. Conversely, the occupancy number of
σ*(I-I) in 3a is 0.384. The increases in both bond distance
and charges of the diiodine moiety and σ*(I-I) occupancy
2.1871(13)
2.7196(6)
2.9742(5)
2.291
3.069
3.024
3.148
2.978
suggest charge transfer from the Se atom to I takes place,
Bond Angles
2
which results in population of the σ* molecular orbital of the
acceptor. In fact, the NBO calculation indicated that the
charge transfer from n(Se) to σ*(I-I) stabilizes the system by
P-Se-I
Se-I-I
102.4
172.3
98.5
180.0
105.1
177.0
Torsion Angles
5
4.46 kcal/mol.
b
P-Se-I-I
12.8
N/A
6.6
It is clear from Table 2 that the I-I distance in the model
Charges
i
compound ( PrO) PSeI (X), a typical tertiary phosphine
3
2
˚
selenide, is 2.978 A longer than that in free I (2.863 A)
˚
P
Se
I
1.305
1.917
2
-0.382
-0.261
-0.097
-0.370
-0.192
-0.077
˚
and is comparable to that in 3a (3.024 A), suggesting that the
charge transfer also takes place between the Se and I in X;
however,fewer electrons are transferred from Se to I in X as
compared with 3a, which is further manifested by the
occupancy number of σ*(I-I) (0.288) and the stabilization
energy of the n(Se)fσ*(I-I) transition (37.44 kcal/mol).
The extent of charge-transfer differences between Se and
I-I in 3a and X can be plausibly attributed to the charge of
the P atom, which is more electropositive (1.917) in X than in
3a (1.300). As a result, more electron density is transferred
from Se (donor) to I-I (acceptor) in 3a, which, in turn,
weakens the I-I bond strength as mentioned above.
Therefore, this confirms the formation of a stronger CT
complex in the case of 3a, a secondary phosphine selenide.
In this paper we have demonstrated the successful synth-
esis of secondary selenophosphito iron complexes 1a-c and
presented the structure of 1b, which is essentially the same as
that of the previously reported 1a. We also presented the
nucleophilic behavior of the metalloligands 1a-c, which can
form 2a-c with methylating agents, and we have structurally
characterized 2b. The relative disposition of the Se atom in
space in 2b is surprisingly different from that of
I
a
Calculations were carried at the B3LYP/LanL2DZ level, and
charges were estimated by natural population analysis. Bond lengths
b
are given in A and angles in deg. Data not available due to the linearity
˚
of Se-I-I.
In order to categorize the nature of the D I adduct
2
according to Deplano’s classification, the I-I bond order,
n(I-I), was evaluated using the Pauling equation:
3
1
7
nðI-IÞ ¼ 10½d0ðI-IÞ -dðI-IÞꢀ=c
where d(I-I) and d (I-I) are the I-I bond distances in the
adduct and free molecule in the gas phase, respectively, and
c is an empirical constant equal to 0.85. The d(I-I) value for
3a in the crystal structure is 2.974 A, and an I-I bond order
of 0.433, suggesting that 3a is a type 2 adduct, which can be
0
˚
1
7
further manifested by the asymmetric Se-I-I vibration at
-
1
51 cm observed in the calculated IR spectrum of 3a
1
(Figure 3). Accordingly, it is plausible to expect 3a to be a
type 2 adduct on the basis of the bond order values and
vibration characteristics.
The calculated geometric parameters are in reasonable
agreement with the crystal data as given in Table 2. Of all the
geometric parameters, —Se-I-I and d(Se-I) showed the
most pronounced discrepancies between the theoretical
its precursor, which is correlated to the C-H Se type of
3 3
3
H-bonding interactions present in the lattice of the free
metalloligand. The organoiron phosphito selenide 3a, which
has a formal þ3 oxidation number on its P atom, can be
considered as a secondary phosphito selenide and represents
the first structurally characterized diiodine charge-transfer
adduct of its kind. Metric data comparison with the reported
charge-transfer complexes suggests that the donating ability
of Se in the title complex 3a is as strong as that in
model and crystal structure with deviations of 7.7ꢀ and
˚
.349 A, respectively, as illustrated by the overlay of both
0
structures (Figure S2 (Supporting Information)). Neverthe-
less, the almost linear arrangement of Se-I-I in the theore-
tical model (Table 2), as compared with the crystal structure,
is consistent with the fact that spoke charge-transfer adducts
are linear. In addition to geometrical parameters, the
modeled infrared spectrum (vide supra) is also in good
agreement with the experimental infrared spectrum.
(Et N) PSeI , a tertiary phosphine selenide CT adduct with
2 3 2
the largest I-I distance reported until now. We have also
presented a model study by DFT calculations which proves
that the title compound has better donor ability in order to
form a stronger charge-transfer adduct than the typical
1
8
The NBO atomic charges on diiodine atoms in 3a are
i
tertiary phosphine selenide ( PrO) PSeI , which is correlated
3
2
-
0.097 and -0.261 electrostatic units, which, nevertheless, is
.000 in free diiodine molecules, indicating that the charges
to the difference between the lower (þ3) formal oxidation
0
7
number of the P in the secondary phosphine chalcogenide
compared to that of þ5 in the tertiary compounds.
(
17) Deplano, P.; Ferraro, J. R.; Mercuri, M. L. Coord. Chem. Rev.
999, 188, 71.
18) Antoniadis, C. D.; Hadjikakou, S. K.; Hadjiliadis, N.;
Papakyriakou, A.; Baril, M.; Butler, I. S. Chem. Eur. J. 2006, 12, 6888.
1
(
(19) Odagi, K.; Nakayama, H.; Ishii, K. Bull. Chem. Soc. Jpn. 1990,
63, 3277.

4
962 Organometallics, Vol. 28, No. 17, 2009
Experimental Section
Chiou et al.
3
1
1
77
3
Cp). P NMR (CDCl ): 190.8 (s, JPSe=438.7 Hz). Se NMR
1
-1
(
2013. FAB-MS (m/z): 392.9 [Cp(CO) FeP(SeCH )(OEt) ] .
CDCl
3
): 283.5 (d, JSeP=438.1 Hz). IR (KBr, νCO, cm ): 2056,
þ
Materials and Measurements. All chemicals were purchased
from commercial sources and used as received. Solvents were
purified following standard protocols. All the reactions were
performed in oven-dried Schlenk glassware by using standard
inert-atmosphere techniques. The compounds NH Se P(OR)
2
3
2
[{Cp(CO) FeP(SeI )(OR) } ] (3a-c). [{Cp(CO) FeP(Se)-
2
2
2 2
2
2
0
i
2 2 2 2
(O Pr) } ] (0.1 g, 0.246 mmol) was dissolved in 15 mL of CH Cl
in a 100 mL flask, and I (0.06 g, 0.246 mmol) was added to it.
2
The mixture was stirred for 2.5 h in an ice bath to give a dark red
4
2
2
i
13
(R = Pr, Et) were prepared according to the reported methods.
NH
solution, which was evaporated to dryness under vacuum to give
3a as a dark red solid. Single crystals were obtained by slow
evaporation of an acetone solution of the compound. In a
n
4 2 2
Se P(O Pr) was prepared by following a procedure similar
i
to that reported for the synthesis of NH
4 2 2
Se P(O Pr) by using
n
n-propanol as the solvent instead of 2-propanol. The elemental
analyses were carried out using a Perkin-Elmer 2400 CHN
analyzer. NMR spectra were recorded on a Bruker Advance
DPX300 FT-NMR spectrometer, which operates at 300 MHz
similar procedure the use of [{Cp(CO) FeP(Se)(O Pr) } ]
2 2
2
or [{Cp(CO) FeP(Se)(OEt) } ] instead of [{Cp(CO) FeP(Se)-
2
2 2
i
(O Pr) } ] gives rise to 3b or 3c.
2
2
2
3a. Yield: 94% (0.151 g). Anal. Calcd for C H I FeO PSe:
4
1
3
19 2
1
31
77
31
1
1
for H, 121.49 MHz for P, and 57.24 MHz for Se. The P{ H}
6
C, 23.70; H, 2.91. Found: C, 23.74; H, 3.14. H NMR (acetone-d ):
77
1
31
and Se{ H} NMR spectra were referenced externally against
5% H PO (δ 0 ppm) and PhSeSePh (δ 463 ppm), respectively.
1.27 (m, 12H, CH ), 4.82 (m, 2H, CH), 5.52 (s, 5H, C H ).
P
NMR (acetone-d ): 168.6 (s, JPSe=540.0 Hz). IR (KBr, cm ):
3
5
5
1
-1
8
3
4
6
The chemical shifts (δ) and coupling constants (J) are reported in
ppm and Hz, respectively. IR spectra were recorded on a JASCO
FT-IR 401 spectrometer at 25 ꢀC. Details of the synthesis and
spectral data of compounds 1a and 2a were reported in a previ-
ous communication. Syntheses of new compounds are reported
below.
2009, 2054 (νCO); 519 (νPSe).
3b. Yield: 93% (0.149 g). Anal. Calcd for C H -
1
3
19
I FeO PSe 0.5(CH ) CO: C, 25.32; H, 3.22. Found: C, 24.95;
2
4
3 2
3
1
3
H, 3.51. H NMR (acetone-d ): 1.02 (t, J =7.23 Hz, 6H,
6
HH
11b
CH ), 1.80 (sextet, 4H, CH CH ), 4.19 (m, 4H, OCH ), 5.58 (s,
3 2 3 2
3
5H, C H ). P NMR (acetone-d ): 176.4 (s, JPSe=544.0 Hz).
1
1
5
5
6
-
1
Synthesis. [Cp(CO)
tion, to a mixture of [NH
Cp Fe (CO) (0.81 g, 2.30 mmol) in a flask was added 100 mL of
2
FeP(Se)(OR)
2
] (1b,c). In a typical reac-
] (1.09 g, 3.35 mmol) and
IR (KBr, cm ): 2005, 2050 (νCO); 513 (νPSe).
3c. Yield: 92% (0.143 g). Anal. Calcd for C H -
n
4
(O Pr)
2
PSe
2
1
1
15
2
2
4
I FeO PSe 0.25(CH ) CO: C, 21.87; H, 2.58. Found: C,
2
4
3 2
3
1
3
toluene and this mixture was refluxed in an oil bath with
constant stirring for 4 h. After this the solution mixture was
filtered hot and the filtrate was evaporated to dryness to obtain a
black solid. The pure compound was isolated from the solid by
column chromatography over silica gel, using hexane/ethyl
acetate (10:1) as the eluent. After the first band containing
ferrocene was washed out, pure 1b was eluted out from the
second band and upon evaporation of the solvent it was iso-
6 HH
21.69; H, 2.79. H NMR (acetone-d ): 1.40 (t, J =6.39 Hz,
3
6H, CH ), 4.26 (m, 4H, CH ), 5.56 (s, 5H, Cp). P NMR
1
3
2
-
1
(acetone-d ): 174.9 (J = 560.0 Hz). IR (KBr, cm ): 2009,
6
PSe
2054 (νCO); 517 (νPSe).
X-ray Crystallographic Details. Crystals were mounted on the
tips of glass fibers with epoxy resin. Data were collected on a P4
diffractometer for 2b and for the rest of compounds on an
APEX II diffractometer, using graphite-monochromated Mo
lated as a dark brown solid. In a similar method, use of
PSe
KR radiation (λ=0.710 73 A). Data reduction was performed
˚
n
(O Pr)
21
22
[
NH
4
(OEt)
2
PSe
2
] instead of [NH
4
2
2
] yielded 1c.
with XSCANS and/or SAINT, which corrects for Lorentz
and polarization effects. Empirical absorption corrections
based on ψ scans for 2b and multiscan (SADABS was used)
for the other compounds were performed. Structures were
solved by the use of direct methods, and refinement was
1
b. Yield: 33% (0.135 g). Anal. Calcd for C H FeO PSe: C,
13 19 4
1
8.55; H, 4.73. Found: C, 38.42; H, 4.90. H NMR (CDCl
3
(
3
): 0.93
CH ), 3.84 (m,
3
t, JHH = 7.25 Hz, 6H, CH
H, OCH
3
), 1.64 (m, 4H, CH
2
5
3
31
2
2
), 4.12 (m, 2H, OCH ), 4.97 (s, 5H, C
2
5
H ). P NMR
1
77
2
(
(
CDCl ): 172.5 (s, JPSe= 718.2 Hz). Se NMR (CDCl ): 206.53
3
performed by least-squares methods on F with the SHELXL-
97 package, incorporated in SHELXTL/PC V5.10. The
3
1
-1
23
24
d, JSeP=718.9 Hz). IR (KBr, νCO, cm ): 2041, 1993.
c. Yield: 28% (0.354 g). Anal. Calcd for C11 15FeO
5.04; H, 4.01. Found: C, 35.02; H, 4.08. H NMR (CDCl ): 1.22
1
1b
1
H
4
PSe: C,
crystallographic data of 1a were reported previously. Crystal
data for 1b: C H FeO PSe, M =405.06, monoclinic, space
1
3
3
13 19
4
r
3
(t, J = 7.03 Hz, 6H, CH ), 3.95 (m, 2H, CH ), 4.20 (m, 2H,
HH 3 2
CH
3
), 4.95 (s, 5H, Cp). P NMR (CDCl
1
1
2
3
): 172.7 (s, JPSe=720.5
): 205.4 (d, JSeP = 717.5 Hz). IR (KBr,
77
1
(21) XSCANS, Release 2.21; Siemens Energy and Automation, Inc.,
Madison, WI, 1995.
(22) SAINT, V4.043: Software for the CCD Detector System; Bruker
Analytical X-ray Systems, Madison, WI, 1995.
(23) Sheldrick, G. M. SHELXL-97: Program for the Refinement of
Hz). Se NMR (CDCl
3
-1
νCO, cm ): 2041, 1994.
Cp(CO) FeP(SeCH
tion, [(CH OBF ] (0.15 g, 1.04 mmol) was dissolved in 50 mL
of CH Cl in a flask and [{Cp(CO)
.04 mmol) was added to it. This mixture was stirred for 1 h at
[
2
3 2 4
)(OR) ](BF ) (2b,c). In a typical reac-
3
)
3
4
n
Crystal Structure; University of G €o ttingen:, G €o ttingen, Germany, 1997.
2
2
2 2 2
FeP(Se)(O Pr) } ] (0.42 g,
(
24) SHELXL 5.10 (PC version): Program Library for Structure
1
Solution and Molecular Graphics; Bruker Analytical X-ray Systems,
Madison, WI, 1998.
(25) Becke, A. D. J. Chem. Phys. 1993, 98, 5648.
(26) Lee, C.; Yang, W.; Parr, R. G. Phys. Rev. B 1988, 37, 785.
room temperature under a nitrogen atmosphere and filtered to
get rid of any solid present. The dark red filtrate was evaporated
to dryness to give 2b as a dark red solid.
(
27) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
2
b. Yield: 89% (0.470 g). Anal. Calcd for C14
Se 0.5CH Cl : C, 31.70; H, 4.22. Found: C, 31.71; H, 4.33. H
NMR (acetone-d ): 0.99 (t, J = 7.36 Hz, 6H, CH ), 1.79
4 4
H22BF FeO P-
1
Robb, M. A.; Cheeseman, J. R.; Montgomery, J., J. A.; Vreven, T.;
Kudin, K. N.; Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.;
Barone, V.; Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson,
G. A.; Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.;
Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai,
H.; Klene, M.; Li, X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Bakken,
V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev,
O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.;
Morokuma, K.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.;
Zakrzewski, V. G.; Dapprich, S.; Daniels, A. D.; Strain, M. C.; Farkas,
O. M., D. K.; Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.; Ortiz,
J. V.; Cui, Q.; Baboul, A. G.; Clifford, S.; Cioslowski, J.; Stefanov, B. B.;
Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.; Martin, R. L.; Fox,
D. J. K., T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.;
Challacombe, M.; Gill, P. M. W.; Johnson, B.; Chen, W.; Wong,
M. W.; Gonzalez, C.; Pople, J. A. Gaussian 03, Revision C.02; Gaussian,
Inc., Wallingford, CT, 2004.
3
2
2
3
6
HH
3
3
(
(
(
m, 4H, CH
2
CH
3
), 2.47 (d, JPH=11.88 Hz, 3H, SeCH
3
), 4.21
): 191.2
s, JPSe=437.5 Hz). Se NMR (CDCl ): 281.4 (d, JSeP=438.1
3
1
m, 4H, OCH
2
), 5.73 (s, 5H, Cp). P NMR (CDCl
3
1
77
1
3
-
1
Hz). IR (KBr, νCO, cm ): 2057, 2013. FAB-MS (m/z): 420.9
n
þ
[
Cp(CO)
c. Yield: 90% (0.450 g). Anal. Calcd for C12
Se 0.25CH Cl : C, 29.42; H, 3.73. Found: C, 29.42; H, 3.70. H
2 3 2
FeP(SeCH )(O Pr) ] .
2
4 4
H18BF FeO P-
1
3
2
2
3
NMR (acetone-d ): 1.40 (t, JHH=6.97 Hz, 6H, CH
6
3
), 2.46 (d,
3
J
PH=11.94 Hz, 3H, SeCH ), 4.31 (m, 4H, CH ), 5.73 (s, 5H,
3
2
(20) Perrin, D. D.; Armarego, W. L. F.; Perrin, D. R. Purification of
Laboratory Chemicals, 2nd ed.; Pergamon Press: Oxford, U.K., 1980.

Article
Organometallics, Vol. 28, No. 17, 2009 4963
˚
/n, a = 7.5177(12) A, b = 8.8367(14) A, c = 26.176(4) A,
˚
˚
group P2
1
indicated by real, rather than imaginary, numbers. The bonding
was also analyzed with the natural bond orbital (NBO) analysis
program. Bond order analyses were then taken from the
o
3
˚
β = 91.059(3) , V=1738.6(5) A , Z = 4, T=298(2) K, Fcalcd
=
3
-1
28
1
.547 g/cm , μ = 3.060 mm , 8903 reflections collected, 3054
unique reflections (Rint= 0.0345), used in all calculations, final
R1 and wR2 (I>2σ(I)) 0.0573 and 0.1448, R1 and wR2 (for all
data) 0.0891 and 0.1589, GOF = 1.033. Crystal data for 2b:
C H BF FeO PSe, M = 506.91, triclinic space group P1, a=
Wiberg bond index matrix in the natural atomic orbital
(NAO) basis. In addition, the second-order perturbation
theory analyses of a Fock matrix in an NBO basis were carried
out by examining all possible interactions between localized
NBOs of the idealized Lewis structure (donor) and an
empty non-Lewis orbital (acceptor) and estimating the ener-
getic importance of donor-acceptor (bonding-antibonding)
interactions in the NBO basis by second-order perturbation
theory.
1
4
22
4
4
r
˚
˚
˚
9
.6588(10) A, b = 10.5120(12) A, c = 10.9495(12) A, R =
o o 3
˚
8
5.373(9) , β = 74.666(7) , γ = 79.197(9)ꢀ, V=1052.6(2) A ,
3 -1
Z=2, T = 293(2) K, F
=1.599 g/cm , μ=2.570 mm , 3320
calcd
reflections collected, 2732 unique reflections (R = 0.0207),
which were used in all calculations, final R1 and wR2 (I > 2σ(I))
int
0.0659 and 0.1806, R1 and wR2 (for all data) 0.0807 and 0.1960,
GOF=1.054. Crystal datafor 3a: C H FeI O PSe, M =658.86,
Acknowledgment. This study was financially supported
in part by Grant Nos. NSC 97-2113-M-259-007-MY3 (to
C.W.L.) and NSC 97-2113-M-259-003-MY2 (to M.K.L.)
from the National Science Council of Taiwan. Parts of the
calculations were performed at the National Center for
High-Performance Computing in Taiwan.
1
3
19
2
4
r
˚
triclinic space group P1, a = 9.0495(5) A, b = 9.9012(6) A, c=
˚
o
o
˚
1
1
2.6309(8) A, R = 83.818(2) , β=72.832(2) , γ=78.377(2)ꢀ, V=
3
3
˚
057.73(11) A , Z=2, T=298(2) K, Fcalcd=2.069 g/cm , μ= 5.438
-
1
mm , 10 721 reflections collected, 5239 unique reflections (R =
int
0.0315), which were used in all calculations, final R1 and wR2 (I>
2σ(I)) 0.0377 and 0.0904, R1 and wR2 (for all data) 0.0676 and
0.1018, GOF = 0.999.
Supporting Information Available: CIF files giving X-ray
crystallographic data for compounds 1b, 2b, and 3a, Figures
S1 and S2, and tables giving Cartesian coordinates of all the
DFT computed models. This material is available free of charge
via the Internet at http://pubs.acs.org.
Theoretical Calculations. The optimization calculations for 3a
and the model compound ( PrO) PSeI (X), which is a tertiary
i
3
2
phosphine selenide-diiodine charge-transfer adduct, were car-
ried using Becke’s three-parameter exchange functional com-
2
5
bined with the Lee-Yang-Parr correlation functional
2
6
(
B3LYP) method with the LanL2DZ basis set using the
(
28) Glendening, E. D.; Badenhoop, J. K.; Reed, A. E.; Carpenter,
2
7
Gaussian 03 package. The minimum nature of these optimized
structures was confirmed by the frequency calculations as
J. E.; Bohmann, J. A.; Morales, C. M.; Weinhold, F. NBO 5.0,
University of Wisconsin, Madison, WI, 2001.