Synthesis and structural characterization of lithium and iron complexes containing a chelating phenolate phosphane ligand

Article abstract of DOI:10.1002/ejic.201100260

The preparation and characterization of lithium and iron(II) complexes containing a potentially tridentate biphenolate phosphane ligand are reported. Deprotonation of 2,2′-phenylphosphanyl-bis(4,6-di-tert-butylphenol) (H₂L^Ph) with one or two equivalents of nBuLi in diethyl ether solutions at-35 °C produces binuclear {Li(HL^Ph)(OEt ₂)}₂ or tetranuclear Li₄(L^Ph) ₂(OEt₂)₃, respectively. An X-ray study of {Li(HL^Ph)(OEt₂)}₂ showed it to be a C _i-symmetric dimer composed of two Li(HL^Ph)(OEt ₂) units linked with dative O-Li bonds involving phenolate oxygen donor atoms whereas that of Li₄(L^Ph)₂(OEt ₂)₃ revealed a C₂-symmetric structure in which the two biphenolate phosphane ligands are linked with four lithium atoms that bind to three diethyl ether molecules. Treatment of FeCl₂ with one or two equivalents of Na₂(L^Ph)(DME)₂ in THF at-35 °C generates binuclear Fe₂(L^Ph)₂(THF) ₂ or mononuclear Fe(HL^Ph)₂(THF)₂, respectively. The two iron(II) centers in Fe₂(L^Ph) ₂(THF)₂ are antiferromagnetically coupled.

Full text of DOI:10.1002/ejic.201100260

FULL PAPER
DOI: 10.1002/ejic.201100260
Synthesis and Structural Characterization of Lithium and Iron Complexes
Containing a Chelating Phenolate Phosphane Ligand
Lan-Chang Liang,*[a] Yu-Ning Chang,[a] Huan-Yu Shih,[a] Sheng-Ta Lin,[a] and
Hon Man Lee[b]
Dedicated to Professor John D. Corbett on the occasion of his 85th birthday
Keywords: Lithium / Iron / O,P ligands / Cluster compounds
The preparation and characterization of lithium and iron(II)
complexes containing a potentially tridentate biphenolate
volving phenolate oxygen donor atoms whereas that of
Li4(LPh)2(OEt2)3 revealed a C2-symmetric structure in which
phosphane ligand are reported. Deprotonation of 2,2Ј-phen- the two biphenolate phosphane ligands are linked with four
ylphosphanyl-bis(4,6-di-tert-butylphenol) (H2LPh) with one
or two equivalents of nBuLi in diethyl ether solutions at
–35 °C produces binuclear {Li(HLPh)(OEt2)}2 or tetranuclear
Li4(LPh)2(OEt2)3, respectively. An X-ray study of {Li(HLPh)-
(OEt2)}2 showed it to be a Ci-symmetric dimer composed of
two Li(HLPh)(OEt2) units linked with dative O–Li bonds in-
lithium atoms that bind to three diethyl ether molecules.
Treatment of FeCl2 with one or two equivalents of Na2(LPh)-
(DME)2 in THF at –35 °C generates binuclear Fe2(LPh)2-
(THF)2 or mononuclear Fe(HLPh)2(THF)2, respectively. The
two iron(II) centers in Fe2(LPh)2(THF)2 are antiferromag-
netically coupled.
of interest. For instance, the molecular structures of Li2LPh
complexes vary noticeably upon DME or THF coordina-
tion.[18,20] In this contribution, we describe the syntheses
and structures of diethyl ether adducts of Li(HLPh) and
Introduction
Cluster complexes that exhibit unusual structural and/or
reactivity motifs have attracted considerable attention in the
past decades. Specific molecular architectures may be delib-
erately constructed with the employment of smart bridging
and blocking ligands. Unusual physical properties and/or
chemical transformations may evolve significantly.[1–8] For
instance, lithium phenolate aggregates have been used as
building blocks in the controlled assembly of metal–organic
frameworks.[9] We are currently exploring the reaction and
structural chemistry with metal complexes of hybrid chelat-
ing ligands.[10–17] In particular, a number of Group 1 deriva-
tives of the biphenolate phosphane ligands 2,2Ј-phenyl-
phosphanyl-bis(4,6-di-tert-butylphenolate) ([LPh]2–)[18] and
2,2Ј-tert-butylphosphanyl-bis(4,6-di-tert-butylphenolate)
([LtBu]2–)[19] have been prepared and their structures charac-
terized. The structural preferences of these complexes have
been shown to be a function of several parameters, includ-
ing substituents at the phosphorus donor, incorporation of
solvent molecules, and the electrophilicity and sizes of the
Group 1 metals. Examination of the relationship between
complex structures and these constitutional parameters is
Li2LPh; the structural motif of these molecules is notably
[18]
distinct from those of Li2(LPh)(DME)2
and
{Li2(LPh)(THF)2}2.[20] Utilization of the established
Group 1 complexes of [LPh 2–
for the preparation of iron
]
derivatives is also reported. Investigation of phenolate com-
plexes of iron is intriguing in view of their relevance to
metalloprotein chemistry.[21–24] We note that biphenolate
phosphane complexes of iron are unprecedented although
ligands of this general type have been known since 1980.[25]
Results and Discussion
The isolation of well-defined lithium complexes of
[LPh 2–
that are free of strong coordinating solvents was un-
]
dertaken. The addition of two equivalents of nBuLi to a
pentane or toluene solution of H2LPh at –35 °C cleanly gen-
erated the dilithium derivative as evidenced by 31P{1H}
NMR spectroscopy. The observed 31P NMR chemical shift
at approximately –32 ppm from these experiments is com-
parable to those acquired with well-defined compounds
prepared in DME or THF solutions.[18,20] Attempts to grow
crystals of these solvent-free lithium complexes, however,
led to amorphous precipitates, the 1H NMR spectra of
which are unfortunately featureless. Similar reactions were
[a] Department of Chemistry and Center for Nanoscience &
Nanotechnology, National Sun Yat-sen University,
Kaohsiung 80424, Taiwan
E-mail: lcliang@mail.nsysu.edu.tw
[b] Department of Chemistry, National Changhua University of
Education,
Changhua 50058, Taiwan
Eur. J. Inorg. Chem. 2011, 4077–4082
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FULL PAPER
conducted in diethyl ether solutions, which also led to the Table 1. Selected bond lengths [Å] and bond angles [°] for
{Li(HLPh)(OEt2)}2, Li4(LPh)2(OEt2)3, Fe2(LPh)2(THF)2, and
clean formation of the anticipated dilithium derivative as
Fe(HLPh)2(THF)2.
indicated by 31P{1H} NMR spectroscopy. After standard
{Li(HLPh)(OEt2)}2
work-up, the diethyl ether adduct Li4(LPh)2(OEt2)3 was suc-
cessfully isolated as colorless crystals from a concentrated
P(1)–Li(1)
2.725(15)
1.964(18)
98.4(8)
117.7(8)
74.1(5)
Li(1)–O(1A)
O(1)–Li(1)
O(1A)–Li(1)–O(3)
O(1A)–Li(1)–P(1)
O(3)–Li(1)–P(1)
1.833(16)
1.923(17)
129.9(9)
126.7(8)
97.4(6)
diethyl ether solution at –35 °C. In a separate batch, color- O(3)–Li(1)
less crystals of {Li(HLPh)(OEt2)}2 were also obtained,
though in rather low yield, with a crystal shape apparently
different from that of Li4(LPh)2(OEt2)3. The formation of
{Li(HLPh)(OEt2)}2 was unexpected but ascribed tentatively
to the partial protonation of Li4(LPh)2(OEt2)3 as a result of
trace amounts of moisture present in the solvent employed.
Nevertheless, {Li(HLPh)(OEt2)}2 may be readily prepared
from the reaction of H2LPh with one equivalent of nBuLi
O(1A)–Li(1)–O(1)
O(1)–Li(1)–O(3)
O(1)–Li(1)–P(1)
Li4(LPh)2(OEt2)3
O(1)–Li(1)
Li(3)–O(3A)
O(4)–Li(1)
O(3)–Li(3)
O(1)–Li(1)–O(1A)
1.833(4)
1.833(5)
1.901(7)
1.839(5)
101.0(3)
79.4(5)
128.1(1)
128.4(1)
131.6(4)
96.5(6)
O(1)–Li(2)
O(2)–Li(3)
P(1)–Li(2)
1.894(5)
1.881(7)
2.553(2)
P(1)–Li(2)–P(1A)
O(1A)–Li(2)–P(1)
O(1)–Li(2)–P(1A)
O(3)–Li(3)–O(2)
O(3A)–Li(3)–O(3)
O(1A)–Li(2)–P(1A)
142.5(2)
127.8(5)
127.8(5)
132.5(4)
95.3(2)
in diethyl ether at –35 °C. An analogous reaction involving O(1)–Li(2)–P(1)
H2LPh and NaH in DME gave Na(HLPh)(DME)2.
O(1)–Li(1)–O(4)
O(1A)–Li(1)–O(4)
Figure 1 illustrates the molecular structure of {Li(HLPh)-
O(3A)–Li(3)–O(2)
(OEt2)}2. Selected bond lengths and angles are summarized
O(1)–Li(2)–O(1A)
79.4(5)
in Table 1. The crystals were of poor quality, suffering from
Fe2(LPh)2(THF)2
disorder of the diethyl ether molecules, but sufficient to
O(1)–Fe(1)
1.924(4)
2.078(4)
2.028(4)
2.215(4)
O(2)–Fe(2)
O(3)–Fe(1)
O(4)–Fe(2)
O(6)–Fe(2)
1.890(4)
2.086(4)
2.268(4)
2.206(5)
confirm the identity of this molecule. The Ci-symmetric di-
O(3)–Fe(2)
mer comprises two Li(HLPh)(OEt2) units bridged with two
O(4)–Fe(1)
dative O–Li bonds. The inversion center lies at the central
O(5)–Fe(1)
point of the Li2O2 tetragon. With the presence of a hydroxy P(1)–Fe(1)
2.6443(17) P(1)–Fe(2)
2.4081(16) Fe(1)–Fe(2)
129.51(16) O(1)–Fe(1)–O(3)
2.8221(17)
2.8237(14)
139.28(16)
91.88(16)
97.76(15)
88.90(10)
171.42(12)
52.68(10)
126.52(11)
156.19(15)
94.26(18)
82.55(14)
122.48(12)
99.00(13)
72.50(12)
103.45(13)
153.31(6)
47.42(11)
45.34(9)
P(2)–Fe(2)
group, the phenolate phosphane ligand is a monoanionic
O(1)–Fe(1)–O(4)
κ2-O,P donor to lithium. The coordination geometry at
each lithium core is best described as a severely distorted
tetrahedral.
O(4)–Fe(1)–O(3)
O(4)–Fe(1)–O(5)
O(1)–Fe(1)–P(1)
O(3)–Fe(1)–P(1)
O(1)–Fe(1)–Fe(2)
O(3)–Fe(1)–Fe(2)
P(1)–Fe(1)–Fe(2)
O(2)–Fe(2)–O(6)
O(2)–Fe(2)–O(4)
O(6)–Fe(2)–O(4)
O(3)–Fe(2)–P(2)
O(4)–Fe(2)–P(2)
O(3)–Fe(2)–P(1)
O(4)–Fe(2)–P(1)
O(2)–Fe(2)–Fe(1)
O(6)–Fe(2)–Fe(1)
P(2)–Fe(2)–Fe(1)
88.46(14)
97.29(15)
79.58(12)
88.30(10)
O(1)–Fe(1)–O(5)
O(3)–Fe(1)–O(5)
O(4)–Fe(1)–P(1)
O(5)–Fe(1)–P(1)
141.57(12) O(4)–Fe(1)–Fe(2)
47.18(10)
62.04(4)
89.06(17)
95.40(15)
O(5)–Fe(1)–Fe(2)
O(2)–Fe(2)–O(3)
O(3)–Fe(2)–O(6)
O(3)–Fe(2)–O(4)
175.01(14) O(2)–Fe(2)–P(2)
80.30(10)
76.72(9)
83.81(10)
80.08(9)
O(6)–Fe(2)–P(2)
O(2)–Fe(2)–P(1)
O(6)–Fe(2)–P(1)
P(2)–Fe(2)–P(1)
116.35(12) O(3)–Fe(2)–Fe(1)
133.95(15) O(4)–Fe(2)–Fe(1)
97.93(5)
P(1)–Fe(2)–Fe(1)
55.86(4)
Fe(HLPh)2(THF)2
Fe(1)–O(1)
Fe(1)–O(4)
1.977(3)
2.270(5)
174.40(15) O(1)–Fe(1)–O(3)
92.80(7)
87.20(7)
80.50(8)
86.67(3)
99.83(8)
86.67(3)
173.35(5)
Fe(1)–O(3)
Fe(1)–P(1)
2.260(4)
2.5241(9)
92.80(7)
87.20(7)
180.0
Figure 1. Molecular structure of {Li(HLPh)(OEt2)}2 with thermal
ellipsoids drawn at the 35% probability level. All methyl groups in
tert-butyl and all ethyl groups in coordinated diethyl ether mole-
cules have been omitted for clarity.
O(1)–Fe(1)–O(1A)
O(1A)–Fe(1)–O(3)
O(1A)–Fe(1)–O(4)
O(1)–Fe(1)–P(1)
O(3)–Fe(1)–P(1)
O(1)–Fe(1)–P(1A)
O(3)–Fe(1)–P(1A)
P(1)–Fe(1)–P(1A)
O(1)–Fe(1)–O(4)
O(3)–Fe(1)–O(4)
O(1A)–Fe(1)–P(1)
O(4)–Fe(1)–P(1)
O(1A)–Fe(1)–P(1A) 80.49(8)
O(4)–Fe(1)–P(1A) 93.33(3)
99.83(8)
93.33(3)
The molecular structure of Li4(LPh)2(OEt2)3 is depicted
in Figure 2. In view of the structural motifs of the pre-
viously
established
Li2(LPh)(DME)2,[18]
{Li2(LPh)-
(THF)2}2,[20] and {Li2(LtBu)(DME)}2,[19] the molecular
structure of Li4(LPh)2(OEt2)3 is of interest. It adopts three
diethyl ether and two biphenolate phosphane ligands to to Li3; a coordination mode that is markedly different from
bind to four lithium atoms in an overall C2-symmetric fash- those of Li2(LPh)(DME)2,[18] {Li2(LPh)(THF)2}2,[20] and
ion, leading to the formation of two Li2O2 tetragons that {Li2(LtBu)(DME)}2[19] in which both [LPh 2–
]
and [L ]
tBu 2– act
are nearly orthogonal to each other. The C2 axis coincides as a κ3-O,P,O ligand bound to one of the lithium atoms.
with the Li1–Li2 vector and penetrates through the central Notably, the lithium atoms in Li4(LPh)2(OEt2)3 are three- or
point of the Li3–O3–Li3A–O3A tetragon. The biphenolate four-coordinate whereas those in Li2(LPh)(DME)2,[18]
[19]
phosphane ligand is κ2-O,P bound to Li2 and κ1-O bound {Li2(LPh)(THF)2}2,[20] and {Li2(LtBu)(DME)}2
are four-
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Eur. J. Inorg. Chem. 2011, 4077–4082

Li and Fe Complexes with a Phenolate Phosphane Ligand
or five-coordinate. Such a discrepancy in molecular archi- amount of diethyl ether. Standing a [D8]toluene solution of
tectures highlights the weaker coordinating nature of di- {Li(HLPh)(OEt2)}2 or Li4(LPh)2(OEt2)3 at room tempera-
ethyl ether compared with DME and THF. Though the ture for several hours led to the occurrence of some precipi-
bond lengths and angles of Li4(LPh)2(OEt2)3 are all within tates. The 1H NMR spectra of these solutions are indicative
the expected values for a biphenolate phosphane complex of the presence of C1-symmetric molecules, due possibly to
of lithium, the O–Li distances in Li4(LPh)2(OEt2)3 involving the formation of higher aggregates.[26–28] In agreement with
both phenolate and ethereal oxygen donors are slightly this hypothesis, these precipitates re-dissolve in solution
shorter than those of Li2(LPh)(DME)2 [lengths involving upon addition of an excess of diethyl ether. Similar phen-
phenolate oxygen range from 1.897(6) to 1.985(7) Å and omena were also found for {[LtBu]Li2(DME)}2.[19] Variable-
those involving DME oxygen range from 1.971(6) to temperature 31P{1H} NMR spectroscopic studies of
2.155(6) Å],[18] {Li2(LPh)(THF)2}2 [lengths involving phe- {Li(HLPh)(OEt2)}2 and Li4(LPh)2(OEt2)3 in [D8]toluene
nolate oxygen range from 1.890(3) to 2.148(3) Å and those confirmed the coordination of the soft phosphorus donors
involving THF oxygen range from 1.981(3) to to the hard lithium atoms with a 1:1:1:1 quartet resonance
1.994(3) Å],[20] and {Li2(LtBu)(DME)}2 [lengths involving (1JPLi = 61 Hz), albeit at temperatures lower than –70 °C.
phenolate oxygen range from 1.850(6) to 2.151(7) Å and Consistently, the 7Li{1H} NMR spectrum of {Li(HLPh)-
those involving DME oxygen range from 2.006(7) to (OEt2)}2 at –70 °C exhibits a doublet resonance for the
2.078(7) Å],[19] likely reflecting the lower coordination phosphorus-bound lithium atoms whereas that of Li4(LPh)2-
number of the lithium cores in the former. Consistent with (OEt2)3 shows one triplet and two singlet resonances in a
the anticipated electronic nature of the phosphorus substit- 1:1:2 ratio, reflecting the structural resemblance of these
uents, the P–Li distance of 2.553(2) Å in Li4(LPh)2(OEt2)3 molecules between the solution and the solid state.
is comparable to those of Li2(LPh)(DME)2 [2.573(5) Å][18]
The preparation of iron(II) complexes of biphenolate
and {Li2(LPh)(THF)2}2 (2.499(3) Å][20] but significantly phosphane ligands was undertaken. Reactions involving all
longer than those of {Li2(LtBu)(DME)}2 (2.43 Å established ethereal adducts of Li2LPh, including those iso-
average).[19]
lated and generated in situ, led to intractable materials from
which no well-defined products have been identified thus
far. In contrast, treating FeCl2 with one equivalent of the
[18]
sodium complex Na2(LPh)(DME)2 in THF at –35 °C af-
forded brownish-yellow crystals of binuclear Fe2(LPh)2-
(THF)2 in 47% yield after recrystallization from a diethyl
ether solution. As shown in Figure 3, this molecule has C1
symmetry, with the Fe1 ion being six-coordinate and Fe2
seven. In addition to the coordination of two biphenolate
phosphane ligands, each iron atom is bound to one THF
molecule. The coordination modes of the two [LPh 2–
gands are different: the two iron atoms are bridged with
one phosphorus donor from one [LPh 2–
ligand and two
]
li-
]
phenolate oxygen donors from the other, although the P1–
Fe2 distance of 2.822(2) Å and O4–Fe2 distance of
2.268(4) Å are somewhat long.[24,29–32] The difference of
0.1778 Å between the P1–Fe1 and P1–Fe2 distances high-
lights the semi-bridging nature of this phosphane do-
nor.[33–35] The Fe–Fe distance of 2.824(1) Å in Fe2(LPh)2-
(THF)2 is substantially longer than those found in the di-
Figure 2. Molecular structure of Li4(LPh)2(OEt2)3 with thermal el-
lipsoids drawn at the 35% probability level. All methyl groups in
tert-butyl and all ethyl groups in diethyl ether molecules have been
omitted for clarity.
The solution NMR spectroscopic data of {Li(HLPh)- iron site of Fe-only hydrogenase structures (ca. 2.60 Å)[36,37]
(OEt2)}2 are consistent with what is anticipated from the and their model complexes, such as Fe2(μ-S2C3H6)(CO)6
established X-ray structures; the tert-butyl groups are ob- [2.510(1) Å][38]
and
[Fe2(μ-S2C3H6)(CO)4(CN)2]2–
1
served in the H NMR spectra as three singlet resonances [2.517(1) Å],[39] but appears to be comparable to those in
in a 2:1:1 ratio at room temperature whereas there are four the model complexes of non-heme diiron enzymes, such as
well-resolved signals with equal intensity at –80 °C. The [Fe4O2(O2CPh)7(H2B(pz)2)2]– [2.829(4) Å],[40] (Tol2C6H3-
solution structure of Li4(LPh)2(OEt2)3 is apparently more CO2)4Fe2(μ-OH)2 [2.8843(9) Å],[41] and (Mes2C6H3CO2)4-
symmetric than the solid-state, with the tert-butyl groups Fe2(μ-OCHMe2)2 [2.998(1) Å].[42] Solution NMR spectro-
appearing as two singlet resonances with equal intensity in scopic studies showed that Fe2(LPh)2(THF)2 is 31P NMR
the 1H NMR spectrum at room temperature, consistent silent, indicating this compound to be paramagnetic. The
with a dynamic equilibrium occurring in solution. The effective magnetic moment (μeff) of this complex in solution
coordinated diethyl ether molecules in {Li(HLPh)- at room temperature, determined by the Evans
(OEt2)}2 and Li4(LPh)2(OEt2)3 are presumably labile as evi- method,[43,44] was found to be 7.15 μB, indicating that the
denced by only one set of diethyl ether signals observed in two high-spin FeII centers are antiferromagnetically cou-
the 1H NMR spectra of solutions containing an excess pled.
Eur. J. Inorg. Chem. 2011, 4077–4082
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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4079

L.-C. Liang, Y.-N. Chang, H.-Y. Shih, S.-T. Lin, H. M. Lee
FULL PAPER
the Evans method[43,44] at room temperature is comparable
to that anticipated for a mononuclear high-spin FeII com-
plex.[45]
Conclusion
In summary, we have prepared and structurally charac-
terized a previously elusive diethyl ether adduct of Li2LPh
and that of its singly protonated derivative Li(HLPh). With
the incorporation of OEt2, a somewhat weaker coordinating
motif than DME and THF, complex Li4(LPh)2(OEt2)3 exhi-
bits a molecular architecture distinct from Li2(LPh)-
(DME)2,[18]
{Li2(LPh)(THF)2}2,[20]
and
{Li2(LtBu)-
(DME)}2.[19] The formation of binuclear Fe2(LPh)2(THF)2
is of particular interest in view of its diiron core structure
containing two phenolate oxygen and one phosphane brid-
ges. The isolation of {Li(HLPh)(OEt2)}2 and Fe(HLPh)2-
(THF)2 implies the compatibility of [HLPh]– be an effective
chelating ligand to main-group and transition metals. The
two iron(II) centers in Fe2(LPh)2(THF)2 are antiferromag-
netically coupled.
Figure 3. Molecular structure of Fe2(LPh)2(THF)2 with thermal el-
lipsoids drawn at the 35% probability level. All methyl groups in
tert-butyl and all methylene groups in THF molecules have been
omitted for clarity.
Given the unexpected formation of {Li(HLPh)(OEt2)}2,
which contains a mono-protonated biphenolate phosphane
ligand, we became curious if this phenomenon would occur
similarly for reactions involving Fe2(LPh)2(THF)2. Indeed,
a controlled experiment of Fe2(LPh)2(THF)2 with a sub-
stoichiometric amount of water in THF at –35 °C pro-
duced, though in low isolated yield, brown crystals of
Fe(HLPh)2(THF)2 as indicated by an X-ray diffraction
Experimental Section
General Procedures: Unless otherwise specified, all experiments
were performed under nitrogen using standard Schlenk or glovebox
techniques. All solvents were reagent grade or better and purified
by standard methods. Compounds H2(LPh [46]
)
and Na2(LPh)-
[18]
(DME)2
were prepared according to literature procedures. All
study. Salt metathesis reactions of FeCl2 with two equiva-
other chemicals were obtained from commercial vendors and used
as received. The NMR spectra were recorded on Varian Unity or
Bruker AV instruments. Chemical shifts (δ) are listed as parts per
million downfield from tetramethylsilane and coupling constants
[18]
lents of Na2(LPh)(DME)2
or Na(HLPh)(DME)2 in THF
also generated Fe(HLPh)2(THF)2 in 48 or 80% isolated
yield, respectively. An X-ray study of Fe(HLPh)2(THF)2
(Figure 4) showed it to be a six-coordinate octahedral spe-
cies containing two trans-disposed THF and two trans-dis-
posed phosphorus donors. This complex is thus C2-sym-
metric; the C2 axis coincides with the vector defined by the
two oxygen donor atoms of the coordinated THF. The phe-
nolate phosphane ligands are κ2-O,P bound to iron. Similar
to Fe2(LPh)2(THF)2, the mononuclear Fe(HLPh)2(THF)2 is
also 31P NMR silent. The μeff value of 5.48 μB measured by
1
(J) are given in Hertz. H NMR spectra are referenced using the
residual solvent peak at δ = 2.09 for [D8]toluene (the most upfield
resonance). 31P and 7Li NMR spectra are referenced externally
using 85% H3PO4 at δ = 0 and LiCl in D2O at δ = 0, respectively.
Routine coupling constants are not listed. All NMR spectra were
recorded at room temperature in specified solvents unless otherwise
noted. Elemental analysis was performed on a Heraeus CHN-O
Rapid analyzer.
X-ray Crystallography: Crystallographic data are summarized in
Table 2. Data were collected on a Bruker-Nonius Kappa CCD dif-
fractometer with graphite monochromated Mo-Kα radiation (λ =
0.7107 Å). Structures were solved by direct methods and refined
by full-matrix least-squares procedures against F2 using SHELXL-
97.[47] All full-weight non-hydrogen atoms were refined anisotropi-
cally. Hydrogen atoms were placed in calculated positions. The
structures of Fe2(LPh)2(THF)2 and Fe(HLPh)2(THF)2 contain dis-
ordered diethyl ether molecules. Attempts to obtain a suitable dis-
order model failed. The SQUEEZE procedure of Platon pro-
gram[48] was used to obtain a new set of F2 (hkl) values without
the contribution of solvent molecules, leading to the presence of
significant voids in the structure. The refinement reduced R1 values
to 0.0776 and 0.0713 for Fe2(LPh)2(THF)2 and Fe(HLPh)2(THF)2,
respectively. In {Li(HLPh)(OEt2)}2, one coordinated diethyl ether
molecule is disordered with one ethyl and one methyl substituents
over two conformations. In Li4(LPh)2(OEt2)3, one coordinated di-
ethyl ether molecule is disordered with two orientations crossing a
symmetry element. In both Fe2(LPh)2(THF)2 and Fe(HLPh)2-
Figure 4. Molecular structure of Fe(HLPh)2(THF)2 with thermal
ellipsoids drawn at the 35% probability level. All methyl groups
have been omitted for clarity.
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2011, 4077–4082

Li and Fe Complexes with a Phenolate Phosphane Ligand
Table 2. Crystallographic data for {Li(HLPh)(OEt2)}2, Li4(LPh)2(OEt2)3, Fe2(LPh)2(THF)2, and Fe(HLPh)2(THF)2.
Compound
{Li(HLPh)(OEt2)}2
Li4(LPh)2(OEt2)3
Fe2(LPh)2(THF)2
Fe(HLPh)2(THF)2
Formula
Fw
C38H56LiO3P
598.74
0.13ϫ0.08ϫ0.02
1.094
C80H120Li4O7P2
1283.46
0.75ϫ0.7ϫ0.65
1.076
monoclinic
C2/c
C76H106Fe2O6P2
1289.25
0.24ϫ0.20ϫ0.11
1.067
C76H108FeO6P2
1235.41
0.66ϫ0.60ϫ0.40
1.086
orthorhombic
Ibca
Crystal size [mm3]
Dcalc [Mg/m3]
Crystal system
Space group
triclinic
triclinic
¯
¯
P1
P1
a [Å]
b [Å]
c [Å]
α [°]
10.5366(5)
11.1909(5)
15.9578(9)
83.121(2)
89.630(2)
76.706(2)
1817.61(16)
2
20.5594(3)
21.5581(4)
19.6062(4)
90
114.2490(10)
90
13.517(4)
17.121(4)
18.817(4)
78.679(19)
70.328(16)
89.256(18)
4014.1(16)
2
13.2732(5)
27.1423(10)
41.9311(17)
90
90
90
β [°]
γ [°]
V [Å3]
7923.2(2)
4
15106.3(10)
8
Z
T [K]
200(2)
200(2)
200(2)
200(2)
2θ range [°]
4.30, 50.64
4.42, 50.62
2.42, 50.06
1.94, 50.06
Index ranges (h;k;l)
Total number of reflections
Independent reflections
Rint
–12, –12; –13, 13; –19, 19 –24, 24; –25, 25; –23, 17 –16, 15; –19, 20; –22, 22 –15, 11; –32, 27; –46, 49
25019
30787
25026
28179
6571
7189
13685
6622
0.1610
0.0906
0.0856
0.0415
Absorption coefficient [mm–1]
Data / restraints / parameters
Goodness of fit
Final indices R1 [IϾ2σ(I)]
Final indices wR2 [IϾ2σ(I)]
R1 indices (all data)
wR2 indices (all data)
Residual density [e/Å3]
0.108
6571 / 0 / 417
1.399
0.1562
0.4110
0.2470
0.4579
–0.876 to 0.931
0.104
7189 / 0 / 442
1.048
0.0622
0.1609
0.0922
0.1807
–0.314 to 0.582
0.445
13685 / 0 / 734
0.876
0.0776
0.1803
0.1606
0.2110
–0.598 to 0.715
0.288
6622 / 0 / 412
1.131
0.0713
0.2329
0.0934
0.2587
–0.359 to 2.556
(THF)2, two tert-butyl groups are disordered with the methyl sub-
stituents over two conformations.
= –33.2 (br. s) ppm. 7Li{1H} NMR ([D8]toluene, 194 MHz,
–70 °C): δ = 4.26 (t, JPLi = 65 Hz, 1 Li), 1.76 (s, 1 Li), 1.23 (s, 2
1
Li) ppm.
CCDC-810499 (for {Li(HLPh)(OEt2)}2), -810500 [for Li4(LPh)2-
(OEt2)3], -810501 [for Fe2(LPh)2(THF)2], -810502 [for Fe(HLPh)2-
(THF)2] contain the supplementary crystallographic data for this
paper. These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
Na(HLPh)(DME)2: A DME solution (2 mL) of H2LPh (65 mg,
0.125 mmol) was added to a DME suspension (12 mL) of NaH
(3 mg, 0.125 mmol) at room temperature. The reaction mixture was
stirred at room temperature overnight, resulting in a colorless,
homogeneous solution. All volatiles were removed under reduced
pressure. The solid residue obtained was dissolved in pentane
(10 mL). The pentane solution was then filtered through a pad of
Celite and the solvents evaporated to dryness under reduced pres-
sure to give the product as an off-white solid; yield 85 mg (95%).
1H NMR (C6D6, 300 MHz): δ = 7.59 (br. s, 2 H, ArH), 7.55 (m, 2
H, ArH), 7.21 (m, 2 H, ArH), 6.99 (br. m, 4 H, ArH and OH),
3.09 (s, 8 H, OCH2), 2.93 (s, 12 H, OMe), 1.65 (s, 18 H, CMe3),
1.29 (s, 18 H, CMe3) ppm. 31P{1H} NMR (C6D6, 121 MHz): δ =
–36.1 ppm.
{Li(HLPh)(OEt2)}2: nBuLi (77 μL, 2.5 m in hexane, 0.19 mmol) was
added to a diethyl ether solution (7 mL) of H2LPh (100 mg,
0.19 mmol) at –35 °C. The solution was stirred at room tempera-
ture for 1 h and the solvents evaporated to dryness under reduced
pressure to give the product as an off-white solid; yield 98 mg
(93%). Colorless crystals suitable for X-ray diffraction analysis
were grown from a concentrated diethyl ether solution at –35 °C.
1H NMR ([D8]toluene, 500 MHz): δ = 7.44 (m, 8 H, ArH), 7.05
(m, 8 H, ArH), 6.91 (m, 4 H, ArH and OH), 2.90 (q, 8 H, OCH2),
1.62 (s, 18 H, ArCMe3), 1.49 (s, 18 H, ArCMe3), 1.26 (br. s, 36 H,
ArCMe3), 0.78 (t, 12 H, OCH2CH3) ppm. 31P{1H} NMR ([D8]-
Fe2(LPh)2(THF)2:
A
pre-chilled THF solution (4 mL) of
Na2(LPh)(DME)2 (200 mg, 0.27 mmol) was added to a THF solu-
tion (1 mL) of FeCl2 (34 mg, 0.27 mmol) at –35 °C. The reaction
solution was stirred at room temperature overnight and the solvents
evaporated to dryness under reduced pressure. Toluene (10 mL)
7
toluene, 121.5 MHz): δ = –33.3 (br. s) ppm. Li{1H} NMR ([D8]-
1
toluene, 194 MHz, –70 °C): δ = 1.13 (d, JPLi = 65 Hz) ppm.
Li4(LPh)2(OEt2)3: nBuLi (150 μL, 2.5 m in hexane, 0.38 mmol) was
added to a diethyl ether solution (7 mL) of H2LPh (100 mg, was added and the solution was filtered through a pad of celite and
0.19 mmol) at –35 °C. The solution was stirred at room tempera-
ture for 1 h and the solvents evaporated to dryness under reduced
pressure to give the product as an off-white solid; yield 111 mg
(99%). Colorless crystals suitable for X-ray diffraction analysis
were grown from a concentrated diethyl ether solution at –35 °C.
the solvents evaporated to dryness under reduced pressure. The tan
solid obtained was dissolved in a minimal amount of diethyl ether
(ca. 2 mL) and the solution was cooled to –35 °C to give the prod-
uct as brownish yellow crystals suitable for X-ray diffraction analy-
sis; yield 81 mg (47%). (C76H106Fe2O6P2)(C4H8O)3 (1504.61):
1H NMR ([D8]toluene, 500 MHz): δ = 7.47 (m, 8 H, ArH), 7.17 (t, calcd. C 70.18, H 8.71; found C 69.97, H 8.53. 1H NMR (C6D6,
4 H, ArH), 7.06 (m, 4 H, ArH), 6.97 (m, 2 H, ArH), 3.05 (q, 12 300 MHz): δ = 70.42 (4 H), 49.24 (2 H), 33.18 (4 H), 29.34 (2 H),
H, OCH2), 1.51 (s, 36 H, ArCMe3), 1.21 (s, 36 H, ArCMe3), 0.70 (t,
18.35 (4 H), 9.25 (20 H), 6.75 (18 H), 3.92 (22 H), 2.74 (4 H), 1.63
18 H, OCH2CH3) ppm. 31P{1H} NMR ([D8]toluene, 121.5 MHz): δ (8 H), –25.51 (18 H) ppm.
Eur. J. Inorg. Chem. 2011, 4077–4082
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4081

L.-C. Liang, Y.-N. Chang, H.-Y. Shih, S.-T. Lin, H. M. Lee
FULL PAPER
Fe(HLPh)2(THF)2. Method 1: A pre-chilled THF solution (4 mL)
of Na2(LPh)(DME)2 (300 mg, 0.40 mmol) was added to a THF
solution (1 mL) of FeCl2 (26 mg, 0.20 mmol) at –35 °C. The reac-
tion solution was stirred at room temperature overnight and the
solvents evaporated to dryness under reduced pressure. Diethyl
ether (10 mL) was then added. The solution was filtered through a
pad of celite and concentrated under reduced pressure until the
volume was approximately 2 mL. Cooling the concentrated solu-
tion to –35 °C afforded the product as brown crystals suitable for
X-ray diffraction analysis; yield 118 mg (48%).
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1
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We thank the National Science Council of Taiwan for financial
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Received: March 16, 2011
Published Online: July 26, 2011
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Eur. J. Inorg. Chem. 2011, 4077–4082