Amido Ln(II) Complexes Coordinated by Bi- and Tridentate Amidinate Ligands: Nonconventional Coordination Modes of Amidinate Ligands and Catalytic Activity in Intermolecular Hydrophosphination of Styrenes and Tolane

Article abstract of DOI:10.1021/acs.inorgchem.5b02450

Heteroleptic Ln(II) and Ca(II) amides [tBuC(NC₆H₃-iPr₂-2,6)₂]MN(SiMe₃)₂(THF) (M = Yb (1Yb), Ca (1Ca)), [2-MeOC₆H₄NC(tBu)N(C₆H₃-iPr₂-2,

Full text of DOI:10.1021/acs.inorgchem.5b02450

Article
pubs.acs.org/IC
Amido Ln(II) Complexes Coordinated by Bi- and Tridentate
Amidinate Ligands: Nonconventional Coordination Modes of
Amidinate Ligands and Catalytic Activity in Intermolecular
Hydrophosphination of Styrenes and Tolane
Ivan V. Basalov, Olga S. Yurova, Anton V. Cherkasov, Georgy K. Fukin, and Alexander A. Trifonov*
Institute of Organometallic Chemistry, Russian Academy of Sciences, Tropinina 49, GSP-445, 630950 Nizhny Novgorod, Russia
S
* Supporting Information
ABSTRACT: Heteroleptic Ln(II) and Ca(II) amides [tBuC(NC6H3-
iPr2-2,6)2]MN(SiMe3)2(THF) (M = Yb (1Yb), Ca (1Ca)), [2-
MeOC6H4NC(tBu)N(C6H3-iPr2-2,6)]LnN(SiMe3)2(THF) (Ln = Sm
(2Sm), Yb (2Yb)), and [2-Ph2P(O)C6H4NC(tBu)N(C6H3-Me2-2,6)]-
YbN(SiMe3)2(THF) (3Yb) coordinated by bi- and tridentate amidinate
ligands were obtained by the amine elimination reactions of M[N-
(SiMe3)2](THF)2 (M = Yb, Sm, Ca) with parent amidines in good
yields. Complex [tBuC(NC6H3-iPr2-2,6)2]SmN(SiMe3)2 can be ob-
tained only by a salt metathesis reaction of [tBuC(NC6H3-2,6-
iPr2)2]SmI(THF)2 with NaN(SiMe3)2. Unlike 1Yb and 1Ca in 1Sm the amidinate ligand is coordinated to metal ion in κ1-
amido:η6-arene fashion preventing THF coordination. The derivatives of tridentate amidinate ligands bearing pendant donor 2-
MeOC6H4 or 2-Ph2P(O)C6H4N groups feature nonconventional κ1-N,κ2-O,η6-arene coordination mode. Complexes 1Ca, 1Sm,
1Yb, 2Sm, 2Yb, and 3Yb proved to be efficient catalysts for styrene hydrophosphination with PhPH2 and Ph2PH. In styrene
hydrophosphination with PhPH2 all the catalysts perform excellent chemoselectivity and afford a monoaddition product
secondary phosphine (PhCH2CH2)PhPH. Moreover, all the catalysts perform hydrophosphination reactions regioselectively with
exclusive formation of the anti-Markovnikov addition product. Within the series of complexes coordinated by the same amidinate
ligand catalytic activity decreases in the following order 1Ca ≥ 1Sm>1Yb. The turnover frequencies were in the range of TOF ≈
0.3−0.7 h−1. However, application of tridentate amidinate ligand allowed one to increase catalytic activity significantly: for 2Sm
TOF was found to be 8.3 h−1. For the addition of PhPH2 to para-substituted styrenes catalyzed by 2Sm it was found that
electron-withdrawing substituents (Cl, F) do not affect the reaction rate while electron-donating groups (tBu, OMe) noticeably
slow down the reaction.
chelating monoanionic amidinate fragment [RC(NR)2]− which
INTRODUCTION
■
forms stable complexes with various metal ions across the
Despite the progress which has been done in the field of the
periodic table of elements14 presents a useful platform for
chemistry of Ln(II) complexes during the past two decades1
“tailoring” new versatile ligand systems. Amidinate ligands have
their catalytic properties still remain poorly explored. This is
been successfully employed in Ln(II) chemistry and allowed for
somewhat surprising since the large ionic radii of Ln(II) ions2
the synthesis and isolation of a series of highly reactive
in combination with their strong reducing properties3 make
species.13b,15 Herein, we report on the synthesis, structures of
them promising objects for catalytic applications. Organic
new heteroleptic Ln(II) amido species coordinated by bi- and
derivatives of Ln(III) are well reputed as efficient catalysts (or
tridentate amidinate ligands, and their catalytic activity in
precatalysts) for various transformations involving unsaturated
intermolecular olefin hydrophosphination.
substrates, e.g., polymerization,4 hydrogenation,5 hydrosilyla-
tion,6 hydroamination,7 hydrophosphination,8 hydroalkoxyla-
RESULTS AND DISCUSSION
tion,9 hydrothiolation,9 and hydroboration.10 Only recently first
■
Synthesis. Amine elimination reactions from
[(Me3Si)2N]2M(THF)2 (M = Yb,16 Sm,17 Ca18) were used as
a synthetic approach to a series of heteroleptic M(II)−amido
complexes coordinated by amidinate ligands differening in
denticity and the nature of pendant donor groups. The
reactions of equimolar amounts of [(Me3Si)2N]2M(THF)2 (M
reports on catalytic activity of organic derivatives of Ln(II) in
olefin polymerization11 and hydrosilylation12 appeared. Hydro-
elementation reactions consisting in addition of E−H
functionalities across C−C multiple bonds are atom-economic
processes for the synthesis of valuable compounds that may be
one of the prospective application fields of such divalent
lanthanide complexes. Recent achievements in intermolecular
hydroelementation reactions promoted by Ln(II)13 inspired us
to synthesize new heteroleptic Ln(II) amido complexes. The
Received: October 23, 2015
© XXXX American Chemical Society
A
DOI: 10.1021/acs.inorgchem.5b02450
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Scheme 1. Synthesis of Complexes 1Yb and 1Ca
Scheme 2. Synthesis of Complexes 1SmI and 1Sm
Scheme 3. Synthesis of Complexes 2Sm, 2Yb, and 3Yb
= Yb, Sm, Ca) and proligands 1−3 (Schemes 1 and 3) were
carried out in toluene at ambient temperature or under
moderate heating (70 °C).
mixture. This can be indicative of two reactions occurring in the
mixture: transamination and oxidation of [(Me3Si)2N]2Sm-
(THF)2 by 1. Unfortunately, all attempts to obtain the reaction
products in individual state were unsuccessful. However, we
succeeded to synthesize Sm(II) amide 1Sm via the successive
salt metathesis reactions starting from SmI2(THF)3 (Scheme
2).
It has been reported that the salt metathesis reaction of
equivalent amounts of SmI2(THF)3 and potassium amidinate
1K in THF after recrystallization of the reaction product from
hexane afforded a dimeric iodoamidinate [{tBuC(NC6H3-2,6-
iPr2)2}Sm(THF)(μ-I)]2.15b However, when recrystallization of
the reaction product was carried out from the THF−hexane
mixture we isolated a monomeric Sm(II) complex [tBuC-
(NC6H3-2,6-iPr2)2]SmI(THF)2 (1SmI, 72% yield) containing
one additional THF molecule coordinated to the metal center
(Scheme 2). The reaction of 1SmI with NaN(SiMe3)2 was
carried out in THF, and recrystallization of the reaction product
from hexane allowed for isolation of amido complex [tBuC-
(NC6H3-2,6-iPr2)2]SmN(SiMe3)2 (1Sm) in 57% yield.
Recently, we reported that the reaction of [(Me3Si)2N]2Yb-
(THF)2 and 1 afforded an Yb(II) amide coordinated by
amidinate ligand [tBuC(NC6 H3 -iPr2 -2,6)2 ]YbN-
(SiMe3)2(THF) (1Yb) in 60% yield.15 The calcium analogue
[tBuC(NC6H3-iPr2-2,6)2]CaN(SiMe3)2(THF) (1Ca) was for-
merly prepared starting from CaI2 through a series of salt
metathesis reactions in 53% yield,19 and its synthesis and
structure were published in 2014. At the same time we
synthesized complex 1Ca via the amine elimination approach
which provided 66% yield (Scheme 1).
The attempt of preparation of the samarium analogue via the
transamination reaction failed. The reaction of equimolar
amounts of [(Me3Si)2N]2Sm(THF)2 and 1 afforded a brown
viscous oil after removal of the volatiles in vacuum. The GC
analysis of the volatiles determined the presence of ∼20% of
the expected amount of (Me3Si)2NH, which should form in the
transamination reaction. At the same time no remaining
[(Me3Si)2N]2Sm(THF)2 and 1 were found in the reaction
B
DOI: 10.1021/acs.inorgchem.5b02450
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
It is noteworthy that unlike 1Yb and 1Ca complex 1Sm
despite a larger ion size of Sm2+ (effective ionic radii for CN =
6; Yb2+, 1.02 Å; Sm2+, 1.22 Å; Ca2+ 1.00 Å)2 crystallizes without
coordinated THF molecule. For highly oxophilic Ln(II) ion
this becomes possible due to κ1-amido:η6-arene coordination of
the amidinate ligand. Such a nonconventional coordination
mode of the amidinate ligand has been documented for a series
of Yb(II) and Sm(II) species.15,20,21 Earlier by the example of a
series of Yb(II) and Yb(III) complexes it was demonstrated
that the coordination mode of the [tBuC(NC6H3-2,6-iPr2)2]−
ligand is dependent on metal ion size: oxidation of Yb(II) to
Yb(III) results in the change of coordination mode from κ1-
amido:η6-arene to a “classical” κ1,κ1-N,N-chelating one.15,20,21
The fact that Sm(II) complexes 1SmI, 1Sm, and [{tBuC-
15b
(NC6H3-2,6-iPr2)2}Sm(THF)(μ-I)]2
despite the coordina-
tion number of the metal ion exhibit κ1-amido:η6-arene
coordination is in line with this observation.
Recently, two new tridentate amidines bearing in the side
chain a pendant Lewis base 2-MeOC6H4NC(tBu)NH(2,6-
iPr2C6H3) (2)22a and 2-[Ph2P(O)]C6H4NHC(tBu) = N(2,6-
Me2C6H3) (3)22b were synthesized in our group. We reported
on the synthesis and structure of complex 2Yb which was
obtained by amine elimination reaction of [(Me3Si)2N]2Yb-
(THF)2 with amidine 2.13a In this study using the same
synthetic approach we succeeded to obtain the Sm(II) analogue
2Sm (Scheme 3). The reaction of [(Me3Si)2N]2Sm(THF)2
with 2 was carried out in toluene at ambient temperature and
afforded 2Sm after recrystallization from hexane as black
crystals in 50% yield. Amidine 3 also cleanly reacts with
[(Me3Si)2N]2Yb(THF)2 under similar conditions, resulting in
complex 3Yb in 88% yield.
Figure 1. Molecular structure of [tBuC(NC6H3-iPr2-2,6)2]CaN-
(SiMe3)2(THF) (1Ca). Hydrogen atoms, methyl fragments of the
iPr groups, and carbon atoms of the THF molecule are omitted for
clarity; thermal ellipsoids drawn at the 30% probability level. Bond
lengths (Angstroms) and angles (degrees): Ca(1)−N(3) 2.279(2),
Ca(1)−O(1) 2.345(2), Ca(1)−N(1) 2.359(1), Ca(1)−N(2)
2.360(2), N(1)−C(1) 1.344(2), N(1)−C(6) 1.419(2), N(2)−C(1)
1.342(2), N(2)−C(18) 1.419(2), N(3)−Ca(1)−O(1) 100.08(6),
N(3)−Ca(1)−N(1) 134.61(5), O(1)−Ca(1)−N(1) 114.20(5),
N(3)−Ca(1)−N(2) 132.96(5), N(2)−C(1)−N(1) 112.1(1), C(1)−
N(1)−C(6) 128.9(2).
It should be mentioned that despite the difference of the
ionic sizes of Yb(II) and Sm(II) complexes 2Sm, 2Yb, and 3Yb
feature η6-arene coordination of the aryl substituent to Ln(II)
ions. This indicates that the presence of an O-containing donor
group in the side chain of the amidinate ligand along with metal
ion size are crucial for the coordination mode.
X-ray Diffraction Studies of Complexes 1Ca, 1SmI,
1Sm, 2Sm, and 3Yb. Structure of 1Ca. Transparent crystals
of 1Ca suitable for X-ray study were obtained by slow
concentration of hexane solution at room temperature. The
molecular structure of 1Ca is depicted in Figure 1, and the
structure refinement data are listed in Table S1 (see ESI). The
molecular structure of 1Ca was established by the X-ray
diffraction study which revealed that complexes 1Ca and 1Yb
are isomorphous. The M−N bond distances in complexes 1Ca
(Ca−Namido 2.2778(9) Å; Ca−Namidinate 2.3604(9), 2.3592(8)
Å) and 1Yb (Yb−Namido 2.303(3) Å; Yb−Namidinate 2.378(3),
2.377(3) Å)2 have similar values taking into account the
difference of ionic radii of these metals.
Structure of 1SmI. Crystals of 1SmI suitable for X-ray study
were obtained by slow concentration at room temperature of
the solution in THF/hexane (1:2) mixture. Complex 1SmI
crystallizes as a solvate 1SmI·THF. The molecular structure of
complex 1SmI is depicted in Figure 2, and the structure
refinement data are listed in Table S1 (see ESI).
Figure 2. Molecular structure of [tBuC(NC6H3-iPr2-2,6)2]SmI-
(THF)2(1SmI). Hydrogen atoms, methyl fragments of the iPr groups,
and carbon atoms of the THF molecules are omitted for clarity;
thermal ellipsoids drawn at the 30% probability level. Bond lengths
(Angstroms) and angles (degrees): Sm(1)−O(2S) 2.562(2),
Sm(1)−O(1S) 2.580(2), Sm(1)−N(2) 2.580(2), Sm(1)−Arcenter
2.676(1), Sm(1)−I(1) 3.2389(3), N(2)−C(1) 1.358(3), N(1)−C(1)
1.311(3), N(2)−Sm(1)−I(1) 131.57(5), O(2S)−Sm(1)−I(1)
80.14(5), O(1S)−Sm(1)−I(1) 96.76(5), O(2S)−Sm(1)−C(6)
159.81(7), O(1S)−Sm(1)−C(6) 114.00(6).
The X-ray study revealed that unlike most Ln(II) iodo
complexes 1SmI adopts a monomeric structure with a terminal
iodo ligand. The coordination environment of the Sm(II) ion
in 1SmI is set up by a terminal iodo ligand, one nitrogen atom
of the amidinate ligand, and two oxygen atoms of THF
molecules. Moreover, one of the 2,6-iPr2C6H3 rings is η6-
coordinated to the Sm ion, resulting in the short Sm−C
distances. The average Sm−C bond distance (3.021(3) Å) in
1SmI is shorter than that in complex Cp*Sm(BPh4), which also
exhibits η6-interaction between Sm(II) ion and a phenyl ring
C
DOI: 10.1021/acs.inorgchem.5b02450
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
(3.08 Å)23 but slightly longer compared to a related dimeric
complex [{tBuC(NC6H3-2,6-iPr2)2}Sm(THF)(μ-I)]2 (2.997
Å).15b The Sm−I bond in 1SmI exhibits a length (3.2389(3)
Å) similar to that in seven-coordinate monomeric Sm(II) iodo
complex [(DIP2pyr)LnI(THF)3] (DIP2pyr =2,5-bis{N-(2,6-
diisopropylphenyl)imino methyl}pyrrolyl (3.2233(9) Å),24
but it is slightly longer than the Sm−I bond in six-coordinate
molecules and the Sm(II). The Sm−Namido bond (2.4370(15)
Å) in 1Sm is noticeably shorter than the corresponding bond in
-
seven-coordinate Sm(II) amido phenolate complex {LONO4
}
Sm(N(SiMe3)2) (2.560(7) Å).13b The bond between Sm(II)
ion and the amidinate nitrogen in 1Sm 2.524(3) Å is shorter
than that in 1SmI (2.580(2) Å).
Structure of 2Sm. Recently, we reported on the synthesis
and structural characterization of complex 2Yb.13a The crystals
of samarium congener 2Sm suitable for X-ray study were
obtained by slow concentration of the hexane solution at room
temperature. The molecular structure of complex 2Sm is
depicted in Figure 4, and the structure refinement data are
complex [(TptBu,Me)SmI(THF)2] (3.1908(9) Å, TptBu,Me
=
tris(pyrazolyl)borate).25 The Sm−N bond in 1SmI (2.580(2)
Å) is somewhat longer than the appropriate bond in
[{tBuC(NC6H3-2,6-iPr2)2}Sm(THF)(μ-I)]2 (2.552(4) Å).15b
Coordination of the amidinate ligand in κ1-amido:η6-arene
fashion affects the geometric parameters of the NCN fragment
in 1SmI. Unlike the κ1,κ1-N,N-chelating coordination featuring
similar C−N bond distances in amidinate fragment26 as a result
of negative charge delocalization within NCN fragment in
1SmI the amidinate C−N bonds are not equivalent. The length
of one bond, 1.311(3) Å, is consistent with its double-bond
character,28 while the length of the second one (1.358(3) Å) is
close to the length of a single C−N bond.28
Structure of 1Sm. Crystals of 1Sm suitable for X-ray study
were obtained by slow concentration at −18 °C from hexane.
The molecular structure of complex 1Sm is depicted in Figure
3, and the structure refinement data are listed in Table S1 (see
Figure 4. Molecular structure of [2-MeOC6H4NC(tBu)N(C6H3-iPr2-
2,6)]Sm[N(SiMe3)2](THF) (2Sm). Hydrogen atoms, methyl frag-
ments of the iPr groups, and carbon atoms of the THF molecule are
omitted for clarity; thermal ellipsoids drawn at the 30% probability
level. Bond lengths (Angstroms) and angles (degrees): Sm(1)−N(3)
2.472(2), Sm(1)−N(1) 2.571(2), Sm(1)−O(2) 2.593(2), Sm(1)−
O(1) 2.602(2), Sm(1)−Arcenter 2.762(1), N(2)−C(8) 1.301(3),
N(1)−C(8) 1.380(3); N(3)− Sm(1)−N(1) 120.85(6), N(3)−
Sm(1)−O(2) 108.84(6), N(1)−Sm(1)−O(2) 113.31(5), N(3)−
Sm(1)−O(1) 87.23(6), N(1)− Sm(1)−O(1) 62.06(5), O(2)−
Sm(1)−O(1) 80.35(5).
Figure 3. Molecular structure of [tBuC(NC6H3-iPr2-2,6)2]SmN-
(SiMe3)2 (1Sm). Hydrogen atoms and methyl fragments of the iPr
groups are omitted for clarity; thermal ellipsoids drawn at the 30%
probability level. Bond lengths (Angstroms) and angles (degrees):
Sm(1)−N(3) 2.437(3), Sm(1)−N(1) 2.524(3), Sm(1)−Arcenter
2.657(2), Sm(1)−C(6) 3.055(4), Sm(1)−Si(2) 3.440(1), N(1)−
C(1) 1.353(5), N(1)−C(6) 1.410(5), N(2)−C(1) 1.312(5), N(3)−
Sm(1)−N(1) 137.9(1), N(3)−Sm(1)−C(18) 163.7(1), N(1)−
Sm(1)−C(18) 56.0(1), N(2)−C(1)−N(1) 119.8(4), N(1)−Sm(1)−
C(6) 27.2(1).
listed in Table S1 (see ESI). Complex 2Sm has a structure
similar to 2Yb; however, these compounds are not
isomorphous (complex 2S crystallizes in P21/c space group,
while 2Yb in P−1). Similarly to 2Yb complex, 2Sm is bound to
one nitrogen of the N(SiMe3)2− group, one oxygen atom of the
THF molecule, and the tridentate amidinate ligand. The
monoanionic amidinate ligand in 2Sm is coordinated to the
metal center in a rare κ1-N,κ2-O,η6-arene fashion. It should be
noted that the range of the Sm−C distances in 2Sm
(2.987(2)−3.219(2) Å) is much larger compared to 1Sm
(2.957(4)−3.022(4) Å) and 1SmI (2.952(2)−3.055(3) Å).
The average Sm−C bond length in 2Sm (3.095(2) Å) is larger
than that in 1Sm (3.004(4) Å) and 1SmI (3.021(3) Å). Such a
perturbation of the Sm−arene interaction is obviously due to
additional coordination of the OMe group to Sm(II) ion. The
Sm−Namidinate bond distance in 2Sm (2.571(2) Å) matches that
in 1SmI (2.580(2) Å), while the Sm−Namido bond (2.472(2) Å)
is expectedly longer than that in 1Sm (2.437(3) Å).
ESI). According to the X-ray study heteroleptic amide complex
1Sm adopts a monomeric structure. Similarly to 1SmI, the
amidinate ligand in 1Sm is coordinated to the Sm(II) ion in κ1-
amido:η6-arene fashion. The average Sm−C distance (3.004(4)
Å) is slightly shorter than that in 1SmI. Moreover, a short
contact (3.055(4) Å) between Sm(II) ion and the ipso-carbon
of the second 2,6-iPr2C6H3 ring was detected in 1Sm. It is
noteworthy that despite the strong oxophilic nature of
lanthanide ions and the fact that the synthesis was carried
out in THF complex 1Sm does not contain coordinated THF
Structure of 3Yb. The crystals of 3Yb suitable for X-ray
study were obtained by slow concentration of the hexane
D
DOI: 10.1021/acs.inorgchem.5b02450
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
solution at room temperature. The molecular structure of
complex 3Yb is depicted in Figure 5, and the structure
Scheme 4. Catalytic Hydrophosphination of Styrene with
PhPH2
Table 1. Catalytic Hydrophosphination of Styrene with
PhPH2
c
d
no.
precat.
t [h]
conv [%]
sec-P/tert-P [%]
a
1
3Yb
3Yb
3Yb
2Yb
2Sm
2Sm
2Sm
1Ca
1Yb
1Sm
2
26
98:2
97:3
98:2
95:5
97:3
95:5
97:3
96:4
99:1
95:5
a
2
24
2
30
b
3
92
b
4
70
2
86
a
5
63
a
6
6
100
99
b
7
4
b
8
70
70
70
100
41
b
9
b
10
94
a
Figure 5. Molecular structure of [2-Ph2POC6H4NC(tBu)N(C6H3-
Me2-2,6)]Yb[N(SiMe3)2] (3Yb). Hydrogen atoms, methyl fragments
of the iPr groups, and carbon atoms of Ph groups are omitted for
clarity; thermal ellipsoids drawn at the 30% probability level. Bond
lengths (Angstroms) and angles (degrees): Yb(1)−O(1) 2.279(1),
Yb(1)−N(3) 2.315(2), Yb(1)−N(1) 2.497(2), Yb(1)−P(1)
3.3120(4), P(1)−O(1) 1.507(1), O(1)−Yb(1)−N(3) 101.29(5),
O(1)−Yb(1)−N(1) 78.03(5), N(3)−Yb(1)−N(1) 131.95(5),
O(1)−Yb(1)−C(24) 113.69(5).
Reaction[styrene]0/[PhPH2]0/[Precat]0 = 50:50:1 in C6D6, [precat]0
= 17.5 mM, T [°C] = 60 unless otherwise specified. The formation of
secondary phosphine was 100% anti-Markovnikov regiospecific, as
established by NMR spectroscopy. Reaction in neat substrates with
[precat]0 = 80.5 mM, T [°C] = 60. Conversion of styrene, as
b
c
d
determined by NMR spectroscopy. Product chemoselectivity
determined by 31P NMR spectroscopy.
preliminary studies such a high chemoselectivity results from
kinetic control due to the large difference in the values of the
rate constants of addition of primary PhPH2 and secondary
(PhCH2CH2)PhPH phosphines to styrenic substrates. More-
over, all catalysts perform hydrophosphination reactions
regioselectively with exclusive formation of the anti-Markovni-
kov (or 2,1) addition product. As previously demonstrated by
Hill29 and Carpentier30 for intermolecular styrene hydro-
elementations, 2,1-addition to a CC double bond favors
stabilization of a polarized four-membered transition state at
the alkene insertion step due to delocalization of the anionic
charge at benzylic carbon adjacent to the metal ion to the
phenyl ring of styrene. We assume that the same scenario
operates in our case. Both the metal ion and the ligand were
found to affect the catalytic activity. Thus, within the series of
complexes coordinated by the same amidinate ligand catalytic
activity decreases in the following order 1Ca ≥ 1Sm > 1Yb
(Table 1, entries 8−10). The turnover frequencies were in the
range of TOF ≈ 0.3−0.7 h−1. However, application of
tridentate amidinate ligand allowed one to increase catalytic
activity significantly: for 2Sm TOF was found to be 8.3 h−1.
To assess the influence of the electronic properties of
styrenic substrate on reaction rate a series of catalytic tests of
hydrophosphination of styrenes bearing various substituents in
the para position of the aromatic ring with PhPH2 was carried
out. A number of functional groups were found to be tolerated
for the hydrphosphination of styrene. Complex 2Sm which
demonstrated the highest catalytic activity in hydrophosphina-
tion of unsubstituted styrene was chosen as a catalyst. It was
found that electron-withdrawing substituents (Cl, F) do not
affect the reaction rate (Table 2, entries 2 and 3), while for
styrenes containing electron-donating groups (tBu, OMe) a
noticeable decrease of the reaction rate was detected (Table 2,
entries 5 and 6). Unexpectedly in the case of p-Me-styrene
having an electron-donating Me substituent the reaction rate
refinement data are listed in in Table S1 (see ESI). Complex
3Yb crystallizes as a solvate 3Yb·C6H14. The X-ray study
revealed that similarly to 2Yb and 2Sm in complex 3Yb the
amidinate ligand is tridentate and coordinated to the Yb(II) ion
in κ1-N,κ2-O,η6-arene fashion. However, despite the similar
denticity of amidinate ligands in 2Yb and 3Yb the latter does
not contain a coordinated THF molecule. Obviously this results
from higher degree of steric saturation of the Yb(II)
coordination sphere in the case of the six-membered metalla-
cycle 3Yb compared to a five-memebered in 2Yb. Thus, the bite
angle N−Yb−O in 3Yb (78.03(5)°) is noticeably larger
compared to 2Yb (64.85(3)°). The Yb−C distances in 3Yb
fall into a rather narrow range 2.769(2)−2.906(2) Å (compare
to 2.886(3)−3.157(3) Å for 2Yb). The average Yb−C
(2.844(2) Å) and Yb−Namido (2.315(2) Å) bond distances in
3Yb are expectedly shorter than those in 2Yb (3.034(3) and
2.368(2) Å, respectively) due to different coordination
numbers of the metal centers. The same trend was found for
the Yb−O bond (3Yb 2.2799(11) Å; 2Yb 2.483(2) Å), while
the Yb−Namidinate bond in 3Yb (2.4971(14) Å) is somewhat
longer compared to that in 2Yb (2.452(2) Å).
Hydrophosphination Catalysis. Complexes 1Ca, 1Sm,
1Yb, 2Sm, 2Yb, and 3Yb were evaluated as precatalysts in
intermolecular hydrophosphination of styrene with PhPH2 and
Ph2PH. The catalytic tests were performed either in neat
substrates ([styrene]:[PhPH2] = 1:1) or in C6D6 solution at 60
°C in the presence of 2 mol % of precatalyst (Scheme 4). The
representative results are listed in Table 1.
Complexes 1Sm, 1Yb, 1Ca, 2Sm, 2Yb, and 3Yb turned out
to be able to mediate styrene hydrophosphination. All catalysts
were found to be highly chemoselective and afford a
monoaddition productsecondary phosphine (PhCH2CH2)-
PhPH with selectivity typically over 95%.28 According to our
E
DOI: 10.1021/acs.inorgchem.5b02450
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Yb complexes 1Yb, 2Yb, and 3Yb tridentate amidinate ligand
with pendant Ph2PO group provides the highest catalytic
activity (58%, 26%, and 100% conversions). All catalysts
perform hydrophosphination reactions with exceptional
regioselectivity, affording exclusively anti-Markovnikov addition
product.
Complexes 1Sm, 1Yb, 1Ca, 2Sm, 2Yb, and 3Yb enable
addition of PhPH2 to the internal triple CC bond of tolane
(Scheme 6). The results are presented in Table 4. Complete
Table 2. Catalytic Hydrophosphination of Para-Substituted
Styrenes with PhPH2
b
c
no.
precat. t [h]
styrene
conv [%] sec-P/tert-P [%]
a
1
2Sm
2Sm
2Sm
2Sm
2Sm
2Sm
4
4
4
4
4
4
p-H-styrene
p-F-styrene
99
88
99
90
30
14
97:3
98:2
a
2
a
3
p-Cl-styrene
p-Me-styrene
p-tBu-styrene
p-OMe-styrene
97:3
a
4
96:4
a
5
100:0
100:0
a
6
a
Reaction[styrene]0/[PhPH2]0/[Precat]0 = 50:50:1 in neat substrates
Scheme 6. Catalytic Hydrophosphination of Tolane with
PhPH2
with [precat]0 = 80.5 mM. T [°C] = 60. The formation of secondary
phosphine was 100% anti-Markovnikov regiospecific, as established by
b
NMR spectroscopy. Conversion of styrene, as determined by NMR
c
spectroscopy. Product chemoselectivity determined by 31P NMR
spectroscopy.
remains comparable to that of unsubstituted styrene (Table 2,
entry 4). These results are consistent with the previously
reported observations of Hill29 and Carpentier,30 which were
rationalized by the stabilization of the partial negative charge on
the benzylic carbon atom in polarized four-membered ring at
the rate-determining step due to electron-withdrawing para
substituents. In contrast the electron-donating para substituents
in the phenyl ring tend to destabilize this transition state.
Complexes 1Sm, 1Yb, 1Ca, 2Sm, 2Yb, and 3Yb proved to be
able to evolve into styrene hydrophosphination not only
primary PhPH2 but also secondary phosphine Ph2PH (Scheme
5). The catalytic tests were carried out in neat substrates at
Table 4. Catalytic Hydrophosphination of Tolane with
PhPH2
b
c
no.
precat.
t [h]
conv [%]
E/Z [%]
2
3
4
5
6
7
3Yb
2Yb
2Sm
1Ca
1Yb
1Sm
70
70
70
70
70
70
100
37
35
84
56
24
36:64
33:67
28:72
58:42
70:30
83:17
a
Reactions were carried out in neat substrates. [Tolane]0/[PhPH2]0/
b
[Precat]0 = 50:50:1, T [°C] = 60. Conversion of tolane and PhPH2
c
was determined by H and 31P NMR spectroscopy Formation of E
and Z addition products established by 31P NMR spectroscopy.
Reaction time is not optimized.
1
Scheme 5. Catalytic Hydrophosphination of Styrene with
Ph2PH
conversion of substrates was reached when complex 3Yb was
employed. High conversion (84%) was also detected for
complex 1Ca. Surprisingly, in the series of complexes 1Sm,
1Yb, and 1Ca a complex of Sm despite having largest ionic
radius displayed the lowest activity (24% vs 56% for 1Yb).
Complexes 2Yb and 2Sm had low catalytic activities (37% and
35%, respectively). Tolane hydrophosphinations mediated by
all complexes afford mixtures of E- and Z-isomers. The highest
selectivity in the formation of E-isomer was observed for 1Sm
(E:Z = 83:17).
precatalyst concentration 2 mol % at 60 °C. The results of the
catalytic tests are compiled in Table 3. Surprisingly, despite the
Table 3. Data for the Hydrophosphination of Styrene with
Ph2PH
b
no.
precat.
t [h]
conv [%]
1
2
3
4
5
6
3Yb
2Yb
2Sm
1Ca
1Yb
1Sm
2
2
2
2
2
2
100
26
CONCLUSIONS
■
100
100
58
We found that the reactions of M[N(SiMe3)2](THF)2 (M =
Yb, Sm, Ca) with amidines 1−3 cleanly occur in toluene under
mild conditions and afford in good yields the related
heteroleptic amido-amidinates 1Yb, 1Ca, 2Yb, 2Sm, and 3Yb.
Exceptionally, complex 1Sm cannot be obtained via an amine
elimination reaction but only by successive salt metathesis
reactions. Matching our previous observations that bigger ion
size favors κ1-amido:η6-arene coordination of the amidinate
ligand complexes 1Sm and 1SmI exhibit this coordination
mode of [tBuC(NC6H3-iPr2-2,6)2]−. The κ1-amido:η6-arene
coordination of the amidinate ligand allows one to prevent
THF coordination and isolation of 1Sm as a THF-free complex
in contrast to 1Ca and 1Yb. The present study also
demonstrated that the coordination mode of the amidinate
ligand besides the metal ion size also depends on denticity.
Thus, if an amidinate ligand has a pendant donor group (OMe
or Ph2PO) for both Sm(II) and Yb(II) κ1-N,κ2-O,η6-arene
coordination was detected.
100
a
Reaction [styrene]0/[Ph2PH]0/[Precat]0 = 50:50:1, T [°C] = 60.
The formation of sec-P was 100% anti-Markovnikov regiospecific, as
established by NMR spectroscopy. Conversion of styrene,
determined by NMR spectroscopy.
b
higher steric demand of Ph2PH vs PhPH2 the addition reactions
of the former to styrene occur much faster. Thus, for catalysts
1Ca and 1Sm total conversion of substrates in the case of
Ph2PH was reached in 2 h, while for PhPH2 it required 70 h. It
is noteworthy that for both phosphines complexes 1Ca and
1Sm have higher catalytic activity compared to the Yb
compound. Complex 2Sm was much more efficient in styrene
hydrophosphination with Ph2PH compared to the ytterbium
analogue 2Yb (100% vs 26%). Interestingly, within the series of
F
DOI: 10.1021/acs.inorgchem.5b02450
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
57.55; H, 8.41; N, 5.75; Sm, 20.59. Found: C, 57.24; H, 8.19; N, 6.00;
Sm, 20.37.
Complexes 1Sm, 1Yb, 1Ca, 2Sm, 2Yb, and 3Yb proved to be
efficicent catalysts for styrene hydrophoshination with both
PhPH2 and Ph2PH. They enable addition of PhPH2 to styrene
with extremely high chemoselectivity and to afford a
monoaddition productsecondary phosphine (PhCH2CH2)-
PhPH. For both phosphines hydrophosphination reactions are
exceptionally regioselective and provide formation only of the
anti-Markovnikov addition product. Within the series of
complexes coordinated by the same amidinate ligand catalytic
activity decreases in the following order 1Ca ≥ 1Sm > 1Yb
with TOF ≈ 0.3−0.7 h−1. Application of tridentate amidinate
ligand allowed one to increase the catalytic activity vs
complexes of the same metals coordinated by bidentate
amidinate. Complexes 1Sm, 1Yb, 1Ca, 2Sm, 2Yb, and 3Yb
enable addition of PhPH2 to an internal triple CC bond of
tolane, affording mixtures of E- and Z-izomers.
Synthesis of [tBuC(NC6H3-iPr2-2,6)2]CaN(SiMe3)2(THF) (1Ca). A
solution of [{tBuC(NC6H3-2,6iPr2)2}H] (0.737 g, 1.75 mmol) in
toluene (10 mL) was added to a solution of Ca[N(SiMe3)2](THF)2
(0.885 g, 1.75 mmol) in toluene, and the reaction mixture was heated
at 70 °C for 70 h. The volatiles were removed in vacuum, and the solid
residue was dissolved in hexane. Slow concentration of the hexane
solution at room temperature resulted in the formation of yellow
crystals. The mother liquid was decanted, and the crystals were washed
with cold hexane and dried in a vacuum at room temperature for 30
min. Complex 1Ca was isolated in 66% yield (0.800 g). 1H NMR (400
MHz, C6D6): δ = 0.05 (s,18H, SiMe3), 1.02 (s, 9H, C(CH3)3), 1.27
(m, 4H, β-CH, THF), 1.28 (d, 3JHH = 6.8 Hz, 12H, CH(CH3)2), 1.37
3
3
(d, JHH = 6.8 Hz, 12H, CH(CH3)2), 3.5 (sept, JHH = 6.8 Hz, 4H,
CH(CH3)2), 3.7 (m, 4H, α-CH, THF), 7.05−7.15 (complex m,
together 6H, CH Ar). 13C NMR (101 MHz, C6D6) δ = 4.8 (SiCH3),
22.6 (C(CH3)3), 25.8 (CH(CH3)2), 28.5 (β-CH2, THF), 30.7
(CH(CH3)2), 45.1 (C(CH3)3), 69.2 (α-CH2, THF), 122.3 (p-CH,
C6H3), 123.1 (m-CH, C6H3), 140,1 (o-C, C6H3), 146.3 (ipso-C,
C6H3). IR (Nujol, KBr, ν/cm−1): 3335 (m), 1900 (m), 1845 (m),
1790 (m), 1655 (m), 1615 (m), 1585 (m), 1245 (m), 1205 (m), 1170
(m), 1050 (m), 975 (m), 875 (m), 825 (s), 755 (s), 660 (s), 605 (s),
580 (s). Anal. Calcd for C39H69CaN3OSi2 (691.46 g/mol): C, 67.67;
H, 10.05; Ca, 5.79; N, 6.07. Found: C, 67.35; H, 10.45; Ca, 5.69; N,
6.27.
EXPERIMENTAL SECTION
■
General Considerations. All experiments were performed in
evacuated tubes using standard Schlenk-flask or glovebox techniques
with rigorous exclusion of traces of moisture and air. After drying over
KOH, THF and DME were purified by distillation from sodium/
benzophenone ketyl, hexane, and toluene by distillation from sodium/
triglyme benzophenone ketyl prior to use. C6D6 toluene-d8 and THF-
d8 were dried with sodium/benzophenone ketyl and condensed in
vacuum prior to use. [(Me3Si)2N]2M(THF)2 (M = Yb,16 Sm,17 Ca18),
2-MeOC6H4NC(tBu)NH(2,6-R2C6H3),22a and 2-[Ph2P(O)]-
C6H4NHC(tBu) = N(2,6-Me2C6H3)22b were prepared according to
literature procedures. Diphenylphosphine and phenylphosphine were
donated by Synor Ltd., vacuum distilled over CaH2, and then degassed
by freeze−pump−thaw methods.
Synthesis of [2-MeOC6H4NC(tBu)N(C6H3-iPr2-2,6)]SmN-
(SiMe3)2(THF) (2Sm). A solution of 2-MeOC6H4NHC(tBu)N-
(C6H3-iPr2-2,6) (0.200 g, 0.55 mmol) in toluene (10 mL) was
added to a solution of [(Me3Si)2N]2Sm(THF)2 (0.335 g, 0.55 mmol)
in toluene (10 mL) at room temperature. The reaction mixture was
stirred for 1 h, and then volatiles were removed in vacuum. The solid
residue was dissolved in hexane (40 mL), and the resulted solution was
centrifuged. Slow concentration of the hexane solution at room
temperature resulted in the formation of complex 2Sm as black
crystals. The mother liquid was decanted; the crystals were washed
with cold hexane and dried in a vacuum for 30 min. Complex 2Sm was
isolated in 50% yield (0.209 g). IR (Nujol, KBr, ν/cm−1): 2737 (m),
2028 (m), 1790 (m), 1670 (m), 1625 (m), 1584 (m), 1485 (m), 1360
(m), 1245 (m), 1205 (m), 1170 (m), 1110 (m), 1030 (m), 935 (m),
875 (m), 820 (m), 788 (s), 725 (m), 660 (s), 605 (s), 580 (s), 514 (s).
Anal. Calcd for C34H59N3O2Si2Sm (762.41 g/mol): C, 54.57; H, 7.93;
N, 5.61; Sm, 20.09. Found: C, 54.20; H, 7.66; N, 5.39; Sm, 19.88.
Synthesis of [2-Ph2P(O)C6H4NC(tBu)N(C6H3-Me2-2,6)]YbN(SiMe3)2
(3Yb). A solution of 2-[Ph2P(O)]C6H4NHC(tBu)N(2,6-Me2C6H3)
(0.360 g, 0.67 mmol) in toluene (10 mL) was added to a solution of
[(Me3Si)2N]2Yb(THF)2 (0.428 g, 0.67 mmol) in toluene (10 mL) at
room temperature. The reaction mixture was stirred for 1 h, and the
volatiles were removed in vacuum. The solid residue was dissolved in
hexane (40 mL). Slow concentration of the hexane solution at room
temperature resulted in the formation of complex 3Yb as black
crystals. The mother liquid was decanted, and the crystals were washed
with cold hexane and dried in vacuum for 30 min. Complex was
isolated in 84% yield (0.56 g, 0.56 mmol). 1H NMR (400 MHz, C6D6)
δ = 0.08, 0.42 (s, together 18H, SiMe3), 1.16 (s, 9H, C(CH3)3), 2.07(s,
3H, CH3), 2.13 (s, 3H, CH3), 6.35−6.37 (m, 1H, C6H4), 6.65−6.69
(m, 1H, C6H4), 7.66−7.68 (m, 1H, C6H4), 7.51−7.54 (m, 1H,
C6H4P), 6.94−6.96 (m, 3H, p-CH, Ph, and NC6H3Me2), 7.00−7.03
(m, 4H, o-CH, Ph) 7.08−7.11 (m, 6H, m-CH, Ph, and NC6H3 Me2).
13C NMR (101 MHz, C6D6) δ = 2.3, 4.9 (SiCH3), 18.0 (CH3), 18.6
Instruments and Measurements. NMR spectra were recorded
on a Bruker DPX 200 or Bruker Avance DRX-400 spectrometer.
Chemical shifts for 1H and 13C1{H} spectra were referenced internally
using the residual solvent resonances and are reported relative to TMS.
Lanthanide metal analysis was carried out by complexometric
titration.31 C, H, N elemental combustion analysis was performed in
the microanalytical laboratory of IOMC.
Synthesis of [tBuC(NC6H3-2,6-iPr2)2]SmI(THF)2 (1SmI). A solution
of tBuC(NC6H3-2,6-iPr2)2K (1.345 g, 2.93 mmol) in THF (15 mL)
was added to a solution of SmI2(THF)3 (1.825 g, 2.93 mmol) in THF
(20 mL) at room temperature, and the reaction mixture was stirred at
40 °C for 24 h. The precipitate of KI was separated by centrifugation,
and the volatiles were removed in vacuum. The solid residue was
dissolved in toluene (15 mL), the resulting solution was centrifuged,
and toluene was removed in a vacuum. Complex 1SmI was obtained
after recrystallization of the remaining solid by slow concentration of
the THF/hexane (1:2) solution at room temperature. Complex 1SmI
was isolated as brown crystals in 72% yield (1.783 g). IR (Nujol, KBr,
ν/cm−1): 1614 (m), 1585 (m), 1259 (m), 1155 (m), 1108 (m), 1027
(m), 926 (s), 767 (s). Anal. Calcd for C41H67IN2O3Sm (913.22 g/
mol): C, 53.92; H, 7.39; N, 3.06; Sm 16.46. Found: C, 53.59; H, 7.02;
N, 2.80; Sm, 16.17.
Synthesis of [tBuC(NC6H3-2,6-iPr2)2]SmN(SiMe3)2 (1Sm). A
solution of [tBuC(NC6H3-2,6-iPr2)2SmI(THF)2] (1.302 g, 1.55
mmol) in THF (15 mL) was added to a solution of NaN(SiMe3)2
(0.284 g, 1.55 mmol) in THF (10 mL) at room temperature, and the
reaction mixture was stirred at room temperature for 24 h. The
precipitate of NaI was separated by centrifugation, and the volatiles
were removed in vacuum. The solid residue was dissolved in hexane
(15 mL), and the solution was centrifuged. The solution was
concentrated, and the resulted viscous oil was cooled at −18 °C to
give brown crystals of 1Sm. The crystals were washed with cold hexane
and dried in vacuum for 30 min at room temperature. Complex 1Sm
was isolated in 57% yield (0.647 g). IR (Nujol, KBr, ν/cm−1): 3334
(m), 1902 (m), 1845 (m), 1655 (m), 1615 (m), 1585 (m), 1245 (m),
1205 (m), 1170 (m), 1050 (m), 975 (m), 875 (m), 825 (s), 755 (s),
660 (s), 580 (s). Anal. Calcd for C35H61N3Si2Sm (730.40 g/mol): C,
(CH3), 32.3 (C(CH3)), 41.1 (C(CH3)), 117.7 (C6H4), 132.2 (C6H4),
132.3 (C6H4), 133.1 (C6H4), 120.0 (C6H3Me2), 128.97 (Ph), 129.02
(Ph), 130.10 (Ph), 130.80 (C6H3Me2), 134.6 (Ph), 134.7 (Ph), 158.33
(C6H4), 158.8 (C6H3Me2), 171.5 (NCN). IR (Nujol, KBr, ν/cm−1):
1900 (s), 1845 (s), 1790 (s), 1669 (s), 1604 (s), 1577 (s), 1538 (s),
1403 (w), 1311 (s), 1265 (w), 1246 (w), 1223 (w), 1203 (w), 1165
(s) (s), 1153 (s), 1133 (m), 1121 (s), 1100 (s), 1092 (s), 1071 (s),
1029 (s), 998 (w), 947 (w), 825 (w), 755 (w), 660 (w), 580 (w). Anal.
Calcd for C43H57N3OPSi2Yb (856.08 g/mol): C, 56.12; H, 6.70; N,
4.90; Yb, 20.21. Found: C, 55.84; H, 6.38; N, 4.77; Yb, 20.20.
G
DOI: 10.1021/acs.inorgchem.5b02450
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
X-ray Crystallography. The X-ray data for 1Ca, 1Sm, 1Yb, 1SmI,
2Sm, and 3Yb were collected on Agilent Xcalibur E (1Ca, 2Sm, 3Yb)
and Bruker Smart Apex (1Sm, 1Yb, 1SmI) diffractometers (graphite-
monochromated, Mo Kα radiation, ω-scan technique, λ = 0.71073 Å,
T = 100(2) K). The systematic pseudomerohedrically twinning of the
crystal of 1Ca, 1Sm, and 1Yb afforded an empirical absorption
correction using the program TWINABS.32 SADABS33 and
ABSPACK34 were used to perform area-detector scaling and
absorption corrections for 1SmI, 2Sm, and 3Yb. The structures
were solved by direct methods and refined on F2 using SHELXTL.35
For the refinements of 1Ca, 1Sm, and 1Yb a HKLF5 formatted data
file was used. A batch scaling factor was introduced to describe the
twin volume fractions, resulting in a 0.458/0.542 (1Ca), 0.425/0.575
(1Sm), and 0.505/0.495 (1Yb) ratio for the volumes of domains 1 and
2, respectively. All non-hydrogen atoms were found from Fourier
syntheses of electron density and refined anisotropically. All hydrogen
atoms were placed in geometrically idealized positions and treated as
riding with Uiso(H) = 1.2Ueq (Uiso(H) = 1.5 Ueq for the hydrogen
atoms in CH3 groups) of their parent atoms.
(6) Molander, G. A.; Romero, J. A. C. Chem. Rev. 2002, 102, 2161−
2186.
(7) (a) Hong, S.; Marks, T. J. Acc. Chem. Res. 2004, 37, 673−686.
(b) Muller, T. E.; Hultzsch, K. C.; Yus, M.; Foubelo, F.; Tada, M.
̈
Chem. Rev. 2008, 108, 3795−3892. (c) Hultzsch, K. C. Adv. Synth.
Catal. 2005, 347, 367−391.
(8) (a) Kawaoka, A. M.; Marks, T. J. J. Am. Chem. Soc. 2005, 127,
6311−6324. (b) Kawaoka, A. M.; Marks, T. J. J. Am. Chem. Soc. 2004,
126, 12764−12765. (c) Kawaoka, A. M.; Douglass, M. R.; Marks, T. J.
Organometallics 2003, 22, 4630−4632. (d) Douglass, M. R.; Stern, C.
L.; Marks, T. J. J. Am. Chem. Soc. 2001, 123, 10221−10238.
(e) Douglass, M. R.; Marks, T. J. J. Am. Chem. Soc. 2000, 122,
̀
1824−1825. (f) Motta, A.; Fragala, I. L.; Marks, T. J. Organometallics
2005, 24, 4995−5003. (g) Takaki, K.; Koshoji, G.; Komeyama, K.;
Takeda, M.; Shishido, T.; Kitani, A.; Takehira, K. J. Org. Chem. 2003,
68, 6554−6565. (h) Takaki, K.; Takeda, M.; Koshoji, G.; Shishido, T.;
Takehira, K. Tetrahedron Lett. 2001, 42, 6357−6360. (i) Hu, H.; Cui,
C. Organometallics 2012, 31, 1208−1211.
(9) Weiss, C. J.; Marks, T. J. Dalton Trans. 2010, 39, 6576−6588.
(10) (a) Harrison, K. N.; Marks, T. J. J. Am. Chem. Soc. 1992, 114,
9220−9221. (b) Bijpost, E. A.; Duchateau, R.; Teuben, J. H. J. Mol.
Catal. A: Chem. 1995, 95, 121−128.
Crystal data and details of data collection and structure refinement
for 1Ca, 1Sm, 1Yb, 1SmI, 2Sm, and 3Yb are given in Table S1
(Supporting Information). The CCDC files 1430019−1430024
contain supplementary crystallographic data for this paper. These
data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via ccdc.cam.ac.uk/products/csd/
request.
(11) (a) Harder, S. Angew. Chem., Int. Ed. 2004, 43, 2714−2718.
(b) Yasuda, H.; Ihara, E.; Hayakawa, T.; Kakehi, T. J. Macromol. Sci.,
Part A: Pure Appl.Chem. 1997, 34 (10), 1929−1944.
(12) Ruspic, C.; Spielmann, J.; Harder, S. Inorg. Chem. 2007, 46,
5320−5326.
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.inorg-
chem.5b02450.
■
(13) (a) Basalov, I. V.; Rosç a, S. C.; Lyubov, D. M.; Selikhov, A. N.;
S
Fukin, G. K.; Sarazin, Y.; Carpentier, J.-F.; Trifonov, A. A. Inorg. Chem.
2014, 53, 1654−1661. (b) Basalov, I. V.; Dorcet, V.; Fukin, G. K.;
Sarazin, Y.; Carpentier, J.-F.; Trifonov, A. A. Chem. - Eur. J. 2015, 21,
6033−6036.
(14) (a) Edelmann, F. T. Coord. Chem. Rev. 1994, 137, 403−481.
(b) Barker, J.; Kilner, M. Coord. Chem. Rev. 1994, 133, 219−300.
(c) Coles, M. P. Dalton Trans. 2006, 985−1001.
Crystallographic data for 1Ca, 1Yb, 1Sm, 1SmI, 2Sm,
and 3Yb (CIF)
1
Representative H and 13C NMR spectra of ytterbium
(15) (a) Basalov, I. V.; Lyubov, D. M.; Fukin, G. K.; Shavyrin, A. S.;
Trifonov, A. A. Angew. Chem., Int. Ed. 2012, 52, 3444−3447.
(b) Heitmann, D.; Jones, C.; Mills, D. P.; Stasch, A. Dalton Trans.
2010, 39, 1877−1882. (c) Wedler, M.; Noltemeyer, M.; Pieper, U.;
Schmidt, H.-G.; Stalke, D.; Edelmarin, F. T. Angew. Chem., Int. Ed.
Engl. 1990, 29, 894−896. (d) Yan, L.; Liu, H.; Wang, J.; Zhang, Y.;
Shen, Q. Inorg. Chem. 2012, 51, 4151−4160.
and calcium complexes (PDF)
AUTHOR INFORMATION
Corresponding Author
*Phone: 007 831 4623532. Fax: 007 831 4627497. E-mail:
trif@iomc.ras.ru.
■
(16) Tilley, T. D.; Andersen, R. A.; Zalkin, A. J. Am. Chem. Soc. 1982,
104, 3725−3727.
Notes
The authors declare no competing financial interest.
(17) Evans, W. J.; Drummond, D. K.; Zhang, H.; Atwood, J. L. Inorg.
Chem. 1988, 27, 575−579.
(18) Westerhausen, M.; Hartmann, M.; Makropoulos, N.; Wieneke,
B.; Wieneke, M.; Schwarz, W.; Stalkec, D.; Naturforsch, Z. Z.
Naturforsch., B: J. Chem. Sci. 1998, 53, 117.
ACKNOWLEDGMENTS
The study was supported by the Russian Foundation for Basic
■
Research
. We thank Synor Ltd. and
personally Dr. A. Tatarnikov for donation of PhPH2 and
Ph2PH.
(19) Loh, C.; Seupel, S.; Gorls, H.; Krieck, S.; Westerhausen, M. Eur.
J. Inorg. Chem. 2014, 2014, 1312−1321.
(20) Basalov, I. V.; Lyubov, D. M.; Fukin, G. K.; Cherkasov, A. V.;
Trifonov, A. A. Organometallics 2013, 32, 1507−1516.
(21) Tolpygin, A. O.; Cherkasov, A. V.; Fukin, G. K.; Trifonov, A. A.
Inorg. Chem. 2014, 53, 1537−1543.
̈
REFERENCES
■
(1) Bochkarev, M. N. Coord. Chem. Rev. 2004, 248, 835−851.
(2) Shannon, R. D. Acta Crystallogr., Sect. A: Cryst. Phys., Diffr., Theor.
Gen. Crystallogr. 1976, 32, 751−767.
(22) (a) Rad’kov, V. Yu.; Skvortsov, G. G.; Lyubov, D. M.;
Cherkasov, A. V.; Fukin, G. K.; Shavyrin, A. S.; Cui, D.; Trifonov, A. A.
Eur. J. Inorg. Chem. 2012, 2012, 2289−229. (b) Tolpygin, A. O.;
Glukhova, T. A.; Cherkasov, A. V.; Fukin, G. K.; Aleksanyan, D. V.;
Cui, D.; Trifonov, A. A. Dalton Trans. 2015, 44, 16465−16474.
(23) Evans, W. J.; Champagne, T. M.; Ziller, J. W. Organometallics
2007, 26, 1204−1211.
(3) (a) Morss, L. R. Chem. Rev. 1976, 76, 827−841. (b) Finke, R. G.;
Keenan, S. R.; Schiraldi, D. A.; Watson, P. L. Organometallics 1986, 5,
598−601. (c) Bond, A. M.; Deacon, G. B.; Newnham, R. H.
Organometallics 1986, 5, 2312−2316.
(4) (a) Hou, Z.; Wakatsuki, Y. Coord. Chem. Rev. 2002, 231, 1−22.
(b) Nakayama, Y.; Yasuda, H. J. Organomet. Chem. 2004, 689, 4489−
4511. (c) Gromada, J.; Carpentier, J.-F.; Mortreux, A. Coord. Chem.
Rev. 2004, 248, 397−410.
(5) (a) Jeske, G.; Lauke, H.; Mauermann, H.; Swepston, P. N.;
Schumann, H.; Marks, T. J. J. Am. Chem. Soc. 1985, 107, 8091−8103.
(b) Jeske, G.; Schock, L. E.; Swepston, P. N.; Schumann, H.; Marks, T.
J. J. Am. Chem. Soc. 1985, 107, 8103−8110.
(24) Jenter, J.; Gamer, M. T.; Roesky, P. W. Organometallics 2010,
29, 4410−4413.
(25) Zhang, X. W.; Maunder, G. H.; Gieβmann, S.; MacDonald, R.;
Ferguson, M. J.; Bond, A. H.; Rogers, R. D.; Sella, A.; Takats, J. Dalton
Trans. 2011, 40, 195−210.
(26) Edelmann, F. T. Adv. Organomet. Chem. 2008, 57, 183−352.
H
DOI: 10.1021/acs.inorgchem.5b02450
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
(27) Allen, A.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen, G.;
Taylor, R. J. Chem. Soc., Perkin Trans. 2 1987, S1−S19.
(28) Ghebreab, M. B.; Bange, C. A.; Waterman, R. J. Am. Chem. Soc.
2014, 136, 9240−9243.
(29) Brinkmann, C.; Barrett, A. G. M.; Hill, M. S.; Procopiou, P. A. J.
Am. Chem. Soc. 2012, 134, 2193−2207.
(30) (a) Liu, B.; Roisnel, T.; Carpentier, J.-F.; Sarazin, Y. Chem. - Eur.
J. 2013, 19, 13445−13462. (b) Liu, B.; Roisnel, T.; Carpentier, J.-F.;
Sarazin, Y. Angew. Chem., Int. Ed. 2012, 51, 4943−4946.
(31) Lyle, S. J.; Rahman, M. M. Talanta 1963, 10, 1177−1182.
(32) Sheldrick, G. M. TWINABS; Bruker AXS: Madison, WI, 1998.
(33) Sheldrick, G. M. SADABS v.2.01-Bruker/Siemens Area Detector
Absorption Correction Program; Bruker AXS: Madison, WI, 1998.
(34) CrysAlis Pro; Agilent Technologies Ltd.: Yarnton, England,
2012.
(35) Sheldrick, G. M. SHELXTL v.6.12-Structure Determination
Software Suite; Bruker AXS: Madison, WI, 2000.
I
DOI: 10.1021/acs.inorgchem.5b02450
Inorg. Chem. XXXX, XXX, XXX−XXX