Insertion of isocyanate and isothiocyanate into the ln-p σ-bond of organolanthanide phosphides

Article abstract of DOI:10.1021/om2006722

The synthesis, structure, and reactivity of organoyttrium phosphides toward phenyl isocyanate (PhNCO) and phenyl isothiocyanate (PhNCS) are described. Reaction of (Tp^Me2)CpYCH²Ph(THF) (Tp^Me2 = tris(3,5-dimethylpyrazolyl) b

Full text of DOI:10.1021/om2006722

ARTICLE
pubs.acs.org/Organometallics
Insertion of Isocyanate and Isothiocyanate into the LnꢀP σ-Bond of
Organolanthanide Phosphides
Weiyin Yi,† Jie Zhang,*,† Longcheng Hong,† Zhenxia Chen,† and Xigeng Zhou*,†,‡
†Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University,
Shanghai 200433, People's Republic of China
‡State Key Laboratory of Organometallic Chemistry, Shanghai 200032, People's Republic of China
S Supporting Information
b
ABSTRACT: The synthesis, structure, and reactivity of organoyt-
trium phosphides toward phenyl isocyanate (PhNCO) and
phenyl isothiocyanate (PhNCS) are described. Reaction of
(TpMe2)CpYCH2Ph(THF) (TpMe2 = tris(3,5-dimethylpyrazolyl)
borate; Cp = C5H5) with 1 equiv of HPPh2 in THF at ambient
temperature gives an organoyttrium phosphide (TpMe2)CpYPPh2-
(THF) (1). Treatment of 1 with 1 equiv of PhNCO in THF at
ambient temperature results in monoinsertion of PhNCO into the
YꢀP σ-bond to yield complex (TpMe2)CpY[OC(PPh2)NPh]-
(THF) (2), whereas reaction of 1 with 2 equiv of PhNCO affords
the PhNCO diinsertion product (TpMe2)CpY[OC(PPh2)-
N(Ph)C(O)NPh] (4). However, reaction of 1 with PhNCS
under the same conditions is independent of the stoichiometric
ratio and gives only the monoinsertion product (TpMe2)CpY[SC(PPh2)NPh] (3). Moreover, 1 can effectively catalyze the
cyclotrimerization of PhNCO under mild conditions, but does not catalyze the cyclotrimerization of PhNCS. In addition, the
reaction of Cp2LnPPh2(THF) with PhNCS affords the insertion products Cp2Ln[SC(PPh2)NPh](THF) (Ln = Y (6), Er (7), Dy
(8)). All new complexes were characterized by elemental analysis, IR, and/or 1H, 13C and 31P NMR, and their solid-state structures,
except 4, were determined through single-crystal X-ray diffraction analysis. These reactions represent the first example of isocyanate
and isothiocyanate insertions into the LnꢀP σ-bond and provide an efficient method for the construction of phosphaureido,
phosphadiureido, and phosphathioureido ligands.
’ INTRODUCTION
organolanthanide phosphides stabilized by a half-sandwich li-
gand, such as [Me2Si(C5Me4)(NC6H2Me3-2,4,6)], have been
reported.9a However, stoichiometric transformation of the LnꢀP
bond remains little explored.
There is fundamental interest in the reactivity of organo-
lanthanide complexes with unsaturated organic small molecules,
because this is the source for developing new catalytic reactions
and catalysts.1,2 Many efforts have focused on a detailed under-
standing of insertions of such substrates into the LnꢀH,3
LnꢀC,4 LnꢀN,5 or LnꢀS bonds6 of organolanthanide complexes
over the last decades. The accumulated information in this
field indicates that the occurrence of the insertion strongly
depends on the degree of steric saturation around the central
metal ion and the nature of the ligand. In contrast, studies on
the basic chemistry of organolanthanide phosphides have been
very limited,7ꢀ9 despite recent significant advances in catalytic
hydrophosphinylation.9b,c This is mainly due to the weak bond-
ing interaction between a rare-earth ion and a organic phos-
phorus ligand, which renders these complexes difficult to
synthesize and characterize.7 Well-defined organolanthanide
complexes containing organic phosphorus anion ligands are
mainly limited to the divalent lanthanide metals.8 The
first structurally characterized trivalent lanthanocene complexes
bearing the LnꢀP σ-bond was reported in 1986.7c Recently,
The0 scorpionate-supported tris(pyrazolyl)borate ligands
(TpR,R ) have been widely applied in organolanthanide chem-
istry, because their steric profiles can be modified by variation of
the substituents in the 3-positions of the pyrazolyl rings.10
Recently, we have been investigating the synthesis and reactivity
of rare-earth organometallic derivatives with the scorpionate-
supported TpMe2 ligand10c,d and demonstrated that mixed
TpMe2/Cp lanthanide chlorides (TpMe2)CpLnCl(THF) that
are prepared by the cyclopentadienyl-exchange of Cp2LnCl
reacts with KTpMe210c are a suitable precursor for preparation
of a variety of mixed TpMe2/Cp rare-earth derivatives. For
example, transformation of (TpMe2)CpYCl(THF) to (TpMe2
)
CpYCH2Ph(THF) is easily realized via its salt metathesis with
KCH2Ph.11 However, similar reaction of (TpMe2)2LnCl with
Received: July 23, 2011
Published: October 10, 2011
r
2011 American Chemical Society
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dx.doi.org/10.1021/om2006722 Organometallics 2011, 30, 5809–5814
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ARTICLE
KCH2SiMe3 does not afford the corresponding alkyl complex
Synthesis of (TpMe2)CpY[SC(PPh2)NPh] (3). Following the
procedure described for 2, reaction of 1 (0.496 g, 0.70 mmol) with
(TpMe2)2LnCH2SiMe3 due to ligand degradation of TpMe2 12
. To
further explore the reactivity of (TpMe2)CpYCH2Ph(THF), we
investigated its reaction with HPPh2 and thus synthesized the
mixed TpMe2/Cp yttrium phosphide (TpMe2)CpYPPh2(THF).
It has been found that (TpMe2)CpYPPh2(THF) not only under-
goes the YꢀP bond insertions with phenyl isocyanate and phenyl
isothiocyanate under mild conditions but also catalyzes the
cyclotrimerization of phenyl isocyanate through the YꢀP bond
insertion process. Phenyl isothiocyanate insertion into the LnꢀP
σ-bond of Cp2LnPPh2(THF) is also observed. In this contribu-
tion, we would like to report these results.
PhNCS (0.096 g, 0.70 mmol) gave 3 C7H8 as colorless crystals. Yield:
3
0.447 g (74%). Anal. Calcd for C46H50N7BSPY: C, 63.97; H, 5.84; N,
11.35. Found: C, 64.12; H, 5.88; N, 11.12. IR (Nujol, cmꢀ1): 1726 w,
1591 s, 1542 s, 1415 w, 1309 w, 1261 s, 1199 s, 1072 s, 1038 s, 982 s, 903
w, 835 w, 794 s, 695 s, 645 m. 1H NMR (400 MHz, C6D6): δ 8.21ꢀ8.25
(m, 2H, C6H5), 7.61ꢀ7.65 (m, 2H, C6H5), 7.28ꢀ7.31 (m, 2H, C6H5),
7.12ꢀ7.20 (m, 2H, C6H5), 7.01ꢀ7.03 (m, 4H, C6H5), 6.86ꢀ6.92 (m,
3H, C6H5), 6.26 (s, 5H, C5H5), 5.52 (s, 1H, H-4(TpMe2)), 5.49 (s, 1H,
H-4(TpMe2)), 5.47 (s, 1H, H-4(TpMe2)), 2.70 (s, 3H, CH3-TpMe2), 2.18
(s, 3H, CH3-TpMe2), 2.15 (s, 3H, CH3-TpMe2), 2.13 (s, 3H,
CH3-TpMe2), 2.11(s, 3H, CH3-TpMe2), 1.96(s, 3H, CH3-TpMe2). 13CNMR
(100 MHz, C6D6): δ 150.31, 143.90, 137.15, 136.55, 134.31 (d, JPC = 14
Hz), 133.26 (d, JPC = 11 Hz), 129.01, 125.45, 124.08, 124.06, 111.69,
111.85, 106.70, 14.29, 13.04. 31P {1H} (160 MHz, C6D6): δ 7.39.
Synthesis of (TpMe2)CpY[OC(PPh2)N(Ph)CONPh] (4) and
(PhNCO)3 (5). To the 10 mL THF solution of 2 (0.414 g, 0.5 mmol)
was added slowly phenyl isocyanate (0.060 g, 0.5 mmol) at ꢀ35 °C, and
then the reaction mixture was slowly warmed to room temperature.
After stirring overnight at room temperature, all volatile substances were
removed under reduced pressure. The residue was then washed using
hexane and recrystallized in toluene/hexane to give 4 as a yellow powder.
Yield: 0.197 g (45%). Anal. Calcd for C46H47N8BO2PY: C, 63.17; H,
5.42; N, 12.81. Found: C, 62.95; H, 5.27; N, 12.45. IR (Nujol, cmꢀ1):
1607 m, 1586 m, 1540 s, 1199 s, 1070 s, 1034 s, 982 s, 909 m, 842 w, 811
s, 689 s, 665 w, 646 s. 1H NMR (400 MHz, C6D6): δ 6.99ꢀ7.73 (m,
10H, C6H5), 6.72ꢀ6.79 (m, 10H, C6H5), 6.22 (s, 5H, C5H5), 5.68 (s,
2H, H-4(TpMe2)), 5.49 (s, 1H, H-4(TpMe2)), 2.41 (s, 3H, CH3-TpMe2),
2.24 (s, 6H, CH3-TpMe2), 1.97 (s, 6H, CH3-TpMe2), 1.92 (s, 3H,
CH3-TpMe2). 13C NMR (100 MHz, C6D6): δ 169.17, 151.78, 150.38,
145.64, 143.46, 138.85, 135.54 (d, JPC = 19 Hz), 133.14 (d, JPC = 21 Hz), 128.76
(d, JPC = 19 Hz), 128.65, 125.47, 124.22, 125.55, 121.96, 116.01, 113.17,
115.51, 106.48, 14.69, 13.36, 13.26, 13.02. 31P {1H} (160 MHz, C6D6):
δ ꢀ20.05
’ EXPERIMENTAL SECTION
General Procedure. All operations involving air- and moisture-
sensitive compounds were carried out under an inert atmosphere of
purified argon or nitrogen using standard Schlenk techniques. The
solvents of THF, toluene, and n-hexane were refluxed and distilled over
sodium benzophenone ketyl under nitrogen immediately prior to use.
(TpMe2)CpYCH2Ph(THF)11 and Cp2LnPPh2(THF)7c were prepared
according to the procedures described in the literature. Phenyl isocya-
nate, phenyl isothiocyanate, and HPPh2 were purchased from Aldrich
and were used without purification. Elemental analyses for C, H, and N
were carried out on a Rapid CHN-O analyzer. The 1H NMR, 13C NMR,
and 31P NMR spectra were recorded by means of a Bruker DMX-400
NMR spectrometer (FT, 400 MHz for 1H; 100 MHz for 13C; 160 MHz
for 31P).
Synthesis of (TpMe2)CpYPPh2(THF) (1). HPPh2 (0.590 g, 3.00
mmol) was added to a 40 mL THF solution of (TpMe2)CpYCH2Ph-
(THF) (1.84 g, 3.00 mmol) at room temperature. After stirring for
overnight, the solvent was removed under vacuum and the solid residue
was washed with 10 mL of n-hexane for two times. This solid material
was collected by filtration and dried for 5 h on a vacuum line. Yield:
1.78 g (84%). The yellow powder was recrystallized from the mixed
solvent of toluene and n-hexane to give 1 as yellow crystals. Anal. Calcd
for C36H45N6BOPY: C, 61.03; H, 6.40; N, 11.86. Found: C, 60.78; H,
6.33; N, 12.07. IR (Nujol, cmꢀ1): 1573 m, 1543 s, 1261 s, 1202 m, 1071
s, 1033 s, 983 w, 930 m, 860 m, 838 m, 782 m, 695 s, 647 s. 1H NMR (400
MHz, C6D6): δ 7.06ꢀ7.47 (m, 10H, C6H5), 6.42 (s, 5H, C5H5), 5.63 (s,
3H, H-4(TpMe2)), 3.52 (m, 4H, O(CH2CH2)2), 2.41 (s, 9H, CH3-
TpMe2), 2.18 (s, 9H, CH3-TpMe2), 1.28 (m, 4H, O(CH2CH2)2).
13C NMR (100 MHz, C6D6): δ 150.28, 144.57, 140.37 (d, JPC = 14.8
Hz), 134.33 (d, JPC = 17.2 Hz), 133.22 (d, JPC = 18.1 Hz), 128.60,
110.12, 106.22, 70.05, 25.44, 14.61, 13.29. 31P {1H} (160 MHz, C6D6):
δ ꢀ19.07.
PhNCO (10 equiv, 0.830 g, 7.0 mmol) was added slowly to a solution
of 1 (0.497 g, 0.70 mmol) in 30 mL of THF at ꢀ35 °C. The reaction
mixture was warmed slowly to room temperature and then continued to
stir overnight at room temperature. The reaction mixture was concen-
trated to dry. To the residue was added 10 mL of water, and it was
extracted with toluene. The organic portions were dried by Na2SO4. The
solvent was removed in vacuo. Yellow crystals of 5 were obtained by
recrystallization in the mixed solvent of toluene and hexane. Yield:
0.692 g (83%). This product was identified as (PhNCO)3 by MS and
unit cell measurement.4k
Synthesis of Cp2Y[SC(PPh2)NPh](THF) (6). PhNCS (0.140 g,
1.03 mmol) was added to a solution of Cp2YPPh2(THF) (0.490 g,
1.03 mmol) in 20 mL of THF at room temperature. After being stirred for
overnight, the solvent was removed under vacuum and the solid residue
was washed with 5 mL of n-hexane. This solid material was collected by
filtration and was recrystallized from the solvent mixture of THF and
hexane to give 6 as colorless crystals. Yield: 0.485 g (77%). Anal. Calcd
for C33H33NOSPY: C, 64.81; H, 5.44; N, 2.29. Found: C, 64.60; H, 5.32;
N, 2.45. IR (Nujol, cmꢀ1): 1648 m, 1589 s, 1578 w, 1525 w, 1450 s, 1342
m, 1201 m, 1168 m, 1099 m, 1077 s, 1013 s, 975 s, 864 m, 777 s, 696 s,
665 w. 1H NMR (400 MHz, C6D6): δ 7.35ꢀ6.75 (m, 15H, C6H5), 6.36
(s, 10H, C5H5), 3.57 (m, 4H, O(CH2CH2)2), 1.40 (m, 4H, O-
(CH2CH2)2). 13C NMR (100 MHz, C6D6): δ 135.61 (d, JPC = 21
Hz), 135.54 (d, JPC = 19 Hz), 133.20, 132.60, 129.22, 129.12, 128.64,
124.61, 124.34, 111.75, 110.24, 67.95, 25.84. 31P {1H} (160 MHz,
C6D6): δ 12.63.
Synthesis of (TpMe2)CpY[OC(PPh2)NPh](THF) (2). PhNCO
(0.083 g, 0.70 mmol) was added to a solution of 1 (0.497 g, 0.70 mmol)
in 15 mL of THF at room temperature. After being stirred for overnight,
the reaction mixture was worked up by the method described above.
Colorless crystals of 2 were obtained in 76% yield, 0.440 g. Anal. Calcd
for C43H50N7BO2PY: C, 62.41; H, 6.09; N, 11.85. Found: C, 62.29; H,
6.05; N, 11.95. IR (Nujol, cmꢀ1): 1583 m, 1543 s, 1495 w, 1414 w, 1343
w, 1261 s, 1203 s, 1071 s, 1035 s, 1022 s, 921 m, 869 w, 801 s, 785 s, 695 s,
643 s. 1H NMR (400 MHz, C6D6): δ 7.92ꢀ7.96 (m, 4H, C6H5),
7.43ꢀ7.48 (m, 2H, C6H5), 7.35ꢀ7.40 (m, 1H, C6H5), 7.07ꢀ7.20 (m,
8H, C6H5), 6.53 (s, 5H, C5H5), 5.46 (s, 3H, H-4(TpMe2)), 3.54ꢀ3.57
(m, 4H, O(CH2CH2)2), 2.14 (s, 9H, CH3-TpMe2), 2.11(s, 9H,
CH3-TpMe2), 1.37ꢀ1.43 (m, 4H, O(CH2CH2)2). 13C NMR (100 MHz,
C6D6): δ 149.70, 139.71, 138.44 (d, JPC = 10 Hz), 136.52, 134.31
(d, JPC = 18 Hz), 133.18 (d, JPC = 18 Hz), 130.03, 128.82, 128.64,
125.07, 122.09, 111.05, 106.82, 67.87, 25.79, 13.44, 13.32. 31P {1H}
(160 MHz, C6D6): δ ꢀ20.13.
Synthesis of Cp2Er[SC(PPh2)NPh](THF) (7). PhNCS (0.154 g,
1.14 mmol) was added to a solution of Cp2ErPPh2(THF) (0.630 g,
1.14 mmol) in 20 mL of THF at room temperature. After being stirred for
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Scheme 1
overnight, the reaction mixture was worked up by the method described
above. Pink crystals of 7 were obtained in 69% yield, 0.543 g. Anal. Calcd
for C33H33NOSPEr: C, 57.45; H, 4.82; N, 2.03. Found: C, 57.28;
H, 4.70; N, 2.15. IR (Nujol, cmꢀ1): 1649 m, 1588 s, 1578 w, 1521 w,
1450 s, 1342 m, 1262 m, 1168 m, 1075 s, 1013 s, 973 s, 865 m, 740 s,
699 s, 664 w.
Synthesis of Cp2Dy[SC(PPh2)NPh](THF) (8). Following the
procedure described for 6, reaction of Cp2DyPPh2(THF) (0.540 g, 0.98
mmol) with PhNCS (0.132 g, 0.98 mmol) gave 8 as yellow crystals.
Yield: 0.483 g (72%). Anal. Calcd for C33H33NOSPDy: C, 57.85; H,
4.86; N, 2.04. Found: C, 57.70; H, 4.93; N, 2.10. IR (Nujol, cmꢀ1): 1649
m, 1587 s, 1578 w, 1522 w, 1440 s, 1342 m, 1262 m, 1169 m, 1099 m,
1075 s, 1020 s, 974 s, 865 m, 776 s, 695 s, 664 w.
X-ray Data Collection, Structure Determination and Re-
finement. Suitable single crystals of complexes 1ꢀ3 and 6ꢀ8 were
sealed under argon in Lindemann glass capillaries for X-ray structural
analysis. Diffraction data were collected on a Bruker SMART Apex CCD
diffractometer using graphite-monochromated Mo Kα (λ = 0.71073 Å)
radiation. During the intensity data collection, no significant decay was
observed. The intensities were corrected for Lorentz-polarization effects
and empirical absorption with the SADABS program.13 The structures
were solved by the direct method using the SHELXL-97 program.14 All
non-hydrogen atoms were found from the difference Fourier syntheses.
The H atoms were included in calculated positions with isotropic
thermal parameters related to those of the supporting carbon atoms,
but were not included in the refinement. All calculations were performed
using the Bruker Smart program.
Figure 1. ORTEP diagram of (TpMe2)CpYPPh2(THF) (1) with the
probability ellipsoids drawn at the 30% level. Hydrogen atoms are
omitted for clarity. Selected bond lengths (Å) and angles (°): Y1ꢀO1
2.411(3), Y1ꢀN1 2.463(4), Y1ꢀN5 2.480(4), Y1ꢀN3 2.507(4),
Y1ꢀC16 2.677(5), Y1ꢀC18 2.684(5), Y1ꢀC19 2.684(5), Y1ꢀC17
2.686(5), Y1ꢀC20 2.688(5), Y1ꢀP1 2.845(2); O1ꢀY1ꢀP1 100.0(1),
N1ꢀY1ꢀP1 86.6(1), N5ꢀY1ꢀP1 86.4(1), N3ꢀY1ꢀP1 161.0(1).
Scheme 2
’ RESULTS AND DISCUSSION
Synthesis and Characterization of Mixed TpMe2/Cp
Yttrium Phosphide (TpMe2)CpYPPh2(THF) (1). Treatment of
(TpMe2)CpYCH2Ph(THF) with 1 equiv of HPPh2 in THF at
room temperature gave the expected complex (TpMe2)CpYPPh2-
(THF) (1) in 84% isolated yield, companying with release of a
toluene molecule (Scheme 1).
monomer with the yttrium atom bonded to one k3-TpMe2 ligand,
one η5-Cp ring, one PPh2 ligand, and one THF molecule. The
coordination number of the center metal ion is 8. The YꢀP
distance of 2.845(2) Å is in the normal range of LnꢀP σ-bonds.9a,15
The YꢀO(THF) distance is 2.411(3) Å, a normal donor YꢀO
bond length. The YꢀC(Cp) and YꢀN(TpMe2) distances are also in
the normal ranges.10a
Complex 1 is air- and moisture-sensitive and is readily
dissolved in THF and toluene and is sparingly soluble in n-
1
hexane. It was characterized by elemental analysis, IR, and H
Reactions of 1 with PhNCO and PhNCS. With mixed TpMe2
/
NMR spectra, which were in good agreement with the proposed
1
Cp yttrium phosphide 1 in hand, we next explored its reactivity
toward PhNCO and PhNCS. As shown in Scheme 2, 1 was
allowed to react with 1 equiv of PhNCO in THF at ambient
temperature, affording an organoyttrium phosphaureido com-
plex (TpMe2)CpY[OC(PPh2)NPh](THF) (2), indicating that
one isocyanate molecule is inserted into the YꢀP σ-bond of 1.
PhNCS reacts with 1 under the same conditions to yield the
corresponding YꢀP bond insertion product (TpMe2)CpY
[SC(PPh2)NPh] (3). These reactions represent the first example
of isocyanate and isothiocyanate insertion into the lanthanideꢀ
phosphorus bond of organolanthanide complexes and provide a
structure. In H NMR spectra, four single peaks at 6.42, 5.63,
2.41, and 2.18 ppm are attributed to H-Cp, 4-H-TpMe2, 3-Me-
TpMe2, and 5-Me-TpMe2, respectively. The chemical shifts of the
coordinated THF molecule are shown at 3.52 and 1.28 ppm as
two multiplet peaks. The Ph/Cp molar ratio of 2 indicates the
occurrence of the displacement of the CH2Ph group by a
PPh2 unit.
Recrystallization of 1 in toluene/n-hexane afforded pale-
yellow crystals suitable for single-crystal X-ray diffraction anal-
ysis. The molecular structure and important bond lengths/angles
of 1 are displayed in Figure 1. Compound 1 is a solvated
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Figure 2. ORTEP diagram of (TpMe2)CpY[OC(PPh2)NPh](THF)
(2) with the probability ellipsoids drawn at the 30% level. Hydrogen
atoms are omitted for clarity. Selected bond lengths (Å) and angles (°):
Y1ꢀO1 2.352(3), Y1ꢀN1 2.518(3), Y1ꢀO2 2.526(3), Y1ꢀN3
2.530(3), Y1ꢀN5 2.555(3), Y1ꢀN7 2.564(3), P1ꢀC22 1.894(4),
O1ꢀC22 1.271(4), N7ꢀC22 1.304(5); O1ꢀC22ꢀN7 117.7(4),
O1ꢀC22ꢀP1 117.2(3), N7ꢀC22ꢀP1 124.9(3), O1ꢀC22ꢀY1
54.1(2), N7ꢀC22ꢀY1 63.6(2), P1ꢀC22ꢀY1 169.4(2).
Figure 3. ORTEP diagram of (TpMe2)CpY[SC(PPh2)NPh] (3) with
the probability ellipsoids drawn at the 30% level. Hydrogen atoms are
omitted for clarity. Selected bond lengths (Å) and angles (°): Y1ꢀN1
2.410(4), Y1ꢀN5 2.420(5), Y1ꢀN2 2.456(5), Y1ꢀN7 2.579(5),
Y1ꢀS1 2.823(2), S1ꢀC1 1.723(6), P1ꢀC1 1.877(6), N1ꢀC1
1.310(7); N1ꢀC1ꢀS1 117.9(4), N1ꢀC1ꢀP1 120.4(4), S1ꢀC1ꢀP1
121.3(4), N1ꢀC1ꢀY1 51.0(3), S1ꢀC1ꢀY1 67.0(2), P1ꢀC1ꢀY1
170.9(3).
The X-ray structural analysis results show that 2 is a solvated
monomer with the yttrium atom bonded to one k3-TpMe2 ligand,
one η5-cyclopentadienyl ring, one chelating phosphaureido
ligand [OC(PPh2)NPh], and one THF (Figure 2). The coordi-
nation number of the central Y3+ ion is 9. The coordinated
phosphaureido group forms essentially a planar four-membered
ring with the Y atom within experimental errors. The bond angles
around C22 are consistent with sp2 hybridization. The N7ꢀC22
and O1ꢀC22 bond lengths, 1.304(5) and 1.271(4) Å, are in
intermediate values between the corresponding CꢀN and CꢀO
single- and double-bond distances and are similar to the values
observed in (C5H4Me)2Y[OC(NiPr2)NPh](THF) (N1ꢀC1
1.323(5) Å; O1ꢀC1 1.297 (4) Å). These bond parameters
indicate substantial electronic delocalization over the OꢀCꢀN
practical strategy for the in situ construction of phosphaureido
and phosphathioureido ligands.
Further investigation results indicated that 1 is an efficient
catalyst for cyclotrimerization of phenyl isocyanate.4k,l
Treatment of 1 with 10 equiv of PhNCO in THF at room
temperature gave the cyclotrimerization product (PhNCO)3 (5)
in 83% isolated yield. To explore the mechanism of the
cyclotrimerization,16 the subsequent reaction of 2 with another
equivalent of PhNCO under the same conditions was examined,
and the diinsertion product (TpMe2)CpY[OC(PPh2)N(Ph)C-
(O)NPh] (4) was obtained in 45% isolated yield. Treatment of
4 with the third equivalent or excess of PhNCO did not afford the
triinsertion product; instead, the cyclotrimer 5 was isolated
(Scheme 2). We also carried out the reaction of 3 with an excess
of PhNCS under the similar conditions, but only the starting
materials PhNCS and 3 were recovered.
.
.
unit.4k,17 Consistent with this, the YꢀN7 and YꢀO1 distances,
2.564(3) and 2.352(3) Å, are intermediate between the values
observed for a YꢀN and YꢀO single bond distance and a YꢀN
and YꢀO donor bond distance and are comparable to the
corresponding values found in (C5H4Me)2Y[OC(NiPr2)NPh]
(THF) (YꢀN1 2.401(2) Å; YꢀO1 2.285(2) Å).5s The P1ꢀC22
distance is 1.894(4) Å, a typical PꢀC single bond, and is
comparable with that found in [Me2Si(C5Me4)(NC6H2Me3-2,4,6)]
La[(iPrN)2C(PPh2)](THF) (P1ꢀC1 1.915(3) Å).9a The
bond lengths and angles of (TpMe2)CpY unit are in the normal
ranges.
Complexes 2ꢀ4 were characterized by standard spectroscopic
and analytical techniques. In the IR spectra data of 2 and 3, in
addition to the characteristic absorptions assigned to TpMe2 and
Cp groups, a new band is observed at ca. 1583 cmꢀ1 for 2
(1591 cmꢀ1 for 3), which may be assigned to the absorption of
the delocalized mode of the OꢀCꢀN (SꢀCꢀN) unit of the
.
.
.
.
resulting phosphaureido (phosphathioureido) ligand.4k,5s The
bonding mode was further proven by single-crystal X-ray diffrac-
1
tion on complexes 2 and 3. The H NMR spectra of 2 and 3
Positive structural verification of 3 was also provided by a
single-crystal X-ray analysis (Figure 3). The structural determi-
nation results show that 3 is a solvent-free monomer, and the
Ph2P group has combined with PhNCS, forming a four-mem-
bered heterometallacycle. The C1ꢀN1 and C1ꢀS1 bond dis-
tances (1.310(7) and 1.732(6) Å) are in agreement with those
found in {(C5H4Me)2Y[SC(NiPr2)NPh]}2 (C13ꢀN1 1.304(3)
Å; C13ꢀS1 1.727(3) Å).5p The YꢀS bond distance of 2.823(2)
Å is comparable with that found in (C5H4Me)2Nd[η2-SC-
(SPh)NPh](THF) (2.881 Å), if the difference in metallic radii
display two different splitting behaviors of the TpMe2 ligand, viz a
single peak at 5.54 ppm assigned to 4-H-TpMe2 and two single
peaks at 2.14 and 2.11 ppm assigned to 3-Me-TpMe2 and 5-Me-
TpMe2 in 2, three single peaks at 5.52, 5.49, and 5.47
ppm assigned to 4-H-TpMe2 and six single peaks at 2.70, 2.18,
2.15, 2.13, 2.11, and 1.96 ppm assigned to 3-Me-TpMe2 and 5-Me-
TpMe2 in 3. The 1H NMR spectrum of 4 shows the Cp/Ph molar
ratio of 1/4, suggesting that two PhNCO units contact with a
PPh2 group.
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Organometallics
ARTICLE
Scheme 3
ν(SꢀCꢀN) stretching band in the 1587ꢀ1589 cmꢀ1 region.5p
.
.
1
The H NMR spectra of 6 contain resonances at δ 7.35ꢀ6.75
assignable to the phenyl ring, and at 6.36 assignable to the Cp ring.
6ꢀ8 are solvated monomers, different from that of 3. It might be
attributed to the more steric hindrance of the TpMe2 ligand compared
to that of the Cp group. Consistent with this observation, two
characteristic multiplet peaks at 3.58 and 1.32 ppm assigned to a
coordinated THF in the 1H NMR spectra of 6 are present. It should
be noted that the reaction of Cp2YPPh2(THF) with PhNCO under
the same conditions gave a complicated mixture.
As shown in Figure 4, complexes 6ꢀ8 possess similar solvated
mononuclear structures. Selected bond distances and angles are
given in Table 1. The yttrium metal is coordinated to two η5-
cyclopentadienyl rings, one chelating phosphathioureido ligand
[SC(PPh2)NPh], and one THF molecule to form a distorted
bipyramidal geometry. The coordination number of the central
Ln3+ is 9. The Y1ꢀN1 and Y1ꢀS1 distances (2.485(8) and
2.773(5) Å) in 6 are slightly different from the corresponding
values in 3 (2.410(4) and 2.823(2) Å) due to the steric effect of
the coordinated THF unit. The N1ꢀC1, S1ꢀC1, and P1ꢀC1
distances (1.30(1), 1.75(1), and 1.88(1) Å) of the [SC(PPh2)NPh]
unit in 6 are comparable to the corresponding values found in 3
(1.31(1), 1.72(1), and 1.88(1) Å).
The structural parameters of 7 and 8 are very similar to those
found in 6 (Figure 4, Table 1); they have no unusual distances
and angles in the Cp2Ln and [SC(PPh2)NPh] units. The LnꢀN
and LnꢀS distances (2.462(5) and 2.760(5) Å in 7, 2.484(3) Å
and 2.775(5) Å in 8) are similar to the corresponding values
found in 6 (2.485(8) and 2.773(5) Å), if the difference in ionic
radii is considered.15
Figure 4. ORTEP diagram of Cp2Ln[SC(PPh2)NPh](THF) (Ln = Y
(6), Er (7), Dy (8)) with the probability ellipsoids drawn at the 30%
level. Hydrogen atoms are omitted for clarity.
’ CONCLUSIONS
The first organoyttrium phosphide with the TpMe2 ligand,
(TpMe2)CpYPPh2(THF) (1), has been synthesized by the proto-
lysis reaction of the corresponding alkyl complex with HPPh2. 1 can
undergo controllable YꢀP bond mono- or diinsertion with PhNCO,
depending on the stoichiometric ratio, to form the corresponding
phosphaureido or phosphadiureido complex, whereas reaction of 1
with PhNCS gives only the LnꢀP bond monoinsertion product.
Furthermore, 1 can catalyze the cyclotrimerization of PhNCO under
mild conditions, through stepwise insertions of isocyanates into the
YꢀP or N bond. It is found that PhNCS can also insert into the
LnꢀP σ-bond of Cp2LnPPh2(THF). These insertions provide an
efficient route to organolanthanide complexes incorporating phos-
phaureido or phosphathioureido ligands.
Table 1. Selected Bond Lengths (Å) and Angles (°) for 6ꢀ8
Ln = Y (6)
Ln = Er (7)
Ln = Dy (8)
Ln1ꢀO1
2.435(6)
2.485(8)
2.773(6)
1.229(10)
1.750(9)
1.878(10)
59.5(5)
2.429(5)
2.462(5)
2.760(5)
1.281(8)
1.761(6)
1.865(7)
59.1(5)
2.464(3)
2.484(3)
2.775(5)
1.297(5)
1.718(5)
1.877(5)
58.7(5)
Ln1ꢀN1
Ln1ꢀS1
N1ꢀC1
S1ꢀC1
P1ꢀC1
N1ꢀLn1ꢀS1
Ln1ꢀN1ꢀC1
Ln1ꢀS1ꢀC1
N1ꢀC1ꢀS1
N1ꢀC1ꢀP1
S1ꢀC1ꢀP1
102.0(6)
80.8(4)
104.1(4)
81.2(2)
102.1(3)
81.3(2)
’ ASSOCIATED CONTENT
117.7(8)
124.0(7)
118.3(6)
115.6(5)
125.8(5)
118.5(4)
117.9(4)
122.7(3)
119.3(2)
S
Supporting Information. Crystallographic data (CIF
b
files). This material is available free of charge via the Internet
at http://pubs.acs.org.
is considered.15 The P1ꢀC1 (1.877(6) Å) distance is in agree-
ment with that found in 2 (1.894(4) Å).
’ AUTHOR INFORMATION
Reactions of Cp2LnPPh2(THF) with PhNCS. Examples of
insertions into the LnꢀP bond are rare.9a To explore the effect of
the ancillary ligands on the LnꢀP bond insertion, we further
investigated the reactions of Cp2LnYPPh2(THF)7c with PhNCS
and PhNCO. As shown in Scheme 3, reaction of PhNCS with a
solution of Cp2LnPPh2(THF) in THF at room temperature gave
the corresponding insertion products Cp2Ln[SC(PPh2)NPh]-
(THF) (Ln = Y (6), Er (7), Dy (8)). Complexes 6ꢀ8 exhibit the
Corresponding Author
*E-mail: zhangjie@fudan.edu.cn (J.Z.), xgzhou@fudan.edu.cn (X.Z.).
’ ACKNOWLEDGMENT
We thank the NNSF, 973 program (2009CB825300), NSF of
Shanghai, and Shanghai Leading Academic Discipline Project
(B108) for financial support.
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ARTICLE
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