Insertion reactions and catalytic hydrophosphination of heterocumulenes using α-metalated N, N-dimethylbenzylamine rare-earth-metal complexes

Article abstract of DOI:10.1021/om300807k

The reactivity of homoleptic α-metalated dimethylbenzylamine lanthanide complexes (α-Ln(DMBA)₃; Ln = La, Y; DMBA = α-deprotonated dimethylbenzylamine) was probed through a series of stoichiometric insertion and catalytic hydrophosphination reactions. Both rare-earth-metal species inserted 3 equiv of various carbodiimides to form the corresponding homoleptic amidinates. α-La(DMBA)₃ was also found to be a useful precatalyst for the room-temperature hydrophosphination of heterocumulenes to form phosphaguanidines, phosphaureas, and phosphathioureas in moderate to excellent isolated yields. Furthermore, through a series of stepwise stoichiometric protonation and insertion reactions, a plausible mechanism for the hydrophosphination catalysis was investigated.

Full text of DOI:10.1021/om300807k

Article
pubs.acs.org/Organometallics
Insertion Reactions and Catalytic Hydrophosphination of
Heterocumulenes using α‑Metalated N,N‑Dimethylbenzylamine
Rare-Earth-Metal Complexes
Andrew C. Behrle and Joseph A. R. Schmidt*
Department of Chemistry, School of Green Chemistry and Engineering, College of Natural Sciences and Mathematics, The
University of Toledo, 2801 W. Bancroft Street, MS 602, Toledo, Ohio 43606-3390, United States
S
* Supporting Information
ABSTRACT: The reactivity of homoleptic α-metalated
dimethylbenzylamine lanthanide complexes (α-Ln(DMBA)3;
Ln = La, Y; DMBA = α-deprotonated dimethylbenzylamine)
was probed through a series of stoichiometric insertion and
catalytic hydrophosphination reactions. Both rare-earth-metal
species inserted 3 equiv of various carbodiimides to form the
corresponding homoleptic amidinates. α-La(DMBA)3 was also found to be a useful precatalyst for the room-temperature
hydrophosphination of heterocumulenes to form phosphaguanidines, phosphaureas, and phosphathioureas in moderate to
excellent isolated yields. Furthermore, through a series of stepwise stoichiometric protonation and insertion reactions, a plausible
mechanism for the hydrophosphination catalysis was investigated.
various applications such as use as ligands for the stabilization
of metals24 and in medicine,25 complex organic synthesis,26 and
materials chemistry.27 The hydrophosphination of heterocu-
mulenes has recently come under scrutiny as a convenient
means to synthesize phosphorus analogues of guanidines, ureas,
thioureas, and amidines.28−33 Early investigations demonstrated
that alkali-metal amides serve as catalysts for the hydro-
phosphination of carbodiimides,34 while recent work has shown
that constrained-geometry lanthanide catalysts also effect this
transformation but require elevated temperatures (80 °C).23
The product phosphaguanidines are known to be a versatile
ligand class for Al, Y, La, Ti, Zr, Nb, Cu, and Zn species with
broadly tunable properties.35−38 Direct synthesis of phospha-
guanidines from phosphines and carbodiimides does not work;
therefore, metal-catalyzed hydrophosphination of carbodii-
mides, in which the P−H bond is added across the diimine,
reducing the bond order by 1, represents a useful new method
to produce these compounds.
Although Hou has shown that silyl-bridged cyclopentadienyl-
amido lanthanide complexes efficiently catalyze the hydro-
phosphination of carbodiimides, these reactions required
elevated temperatures for catalysis.23 To date, there have
been no reports of successful hydrophosphination of
heterocumulenes at room temperature using a rare-earth-
metal catalyst. As our recent efforts have focused on the
production of new lanthanide complexes,39 we set out to
explore their possible utility in catalytic hydrophosphination
reactions. Herein, we report the room-temperature hydro-
INTRODUCTION
■
In the ever-growing discipline of catalysis, the improvement of
carbon−heteroatom bond-forming reactions remains at the
forefront. The effective catalysis of hydroamination,1−3 hydro-
silylation,4−6 and hydrophosphination7−10 is very attractive, due
to the 100% atom economy involved in these reactions.11 In
contrast to the myriad reported catalysts for hydroamination
and hydrosilylation reactions, the number of known hydro-
phosphination catalysts remains small, although they span the
entire periodic table, with several reports involving late
transition metals.10,12−17 Early-metal catalysts, such as those
of Waterman and Mindiola, have been utilized in the
intermolecular hydrophosphination of alkynes.18,19 Main-
group metals can also be effective, as noted in Cui, Stephan,
and Hill’s reports on alkali-metal- and alkaline-earth-metal-
catalyzed hydrophosphination reactions.8,20,21 Furthermore, the
Marks and Hou groups have shown that even f elements can be
employed, as demonstrated in the hydrophosphination of
olefins and carbodiimides using constrained-geometry lantha-
nide catalysts.22,23 We were especially intrigued by the use of
lanthanides, due to the various possible advantages available
with these metals, such as their electrophilicities, the ability to
tune the steric environment about these metal centers through
a proper choice of supporting ligands, and their absence of
unproductive oxidative addition/reductive elimination reaction
pathways.
Catalytic hydrophosphination of an unsaturated species
yields product phosphines with one more substituent than
the related reactant (e.g., a secondary phosphine is converted to
a tertiary phosphine). In addition to its atom efficiency, this
reaction serves as a convenient way to make unsymmetrically
substituted phosphines (e.g., R2PR′; R ≠ R′). The hydro-
phosphination products are valuable, due to their utility in
Special Issue: Recent Advances in Organo-f-Element Chemistry
Received: August 21, 2012
© XXXX American Chemical Society
A
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Scheme 1. Stoichiometric Insertion of Carbodiimides
phosphination of carbodiimides and isocyanates using homo-
leptic α-metalated N,N-dimethylbenzylamine (DMBA) rare-
earth complexes.
RESULTS AND DISCUSSION
■
We recently reported the synthesis and preliminary proto-
nolysis reactivity of a new class of non-cyclopentadienyl
homoleptic rare-earth-metal complexes utilizing exclusively α-
metalated dimethylbenzylamine supporting ligands.39 In our
ongoing experiments, we sought to expand the reactivity scope
of the α-Ln(DMBA)3 (Ln = La, Y) complexes by investigating
stoichiometric insertion reactions, as well as the related catalytic
processes utilizing both insertion and protonolysis reactions. As
such, complex 1 was synthesized via the stoichiometric reaction
of α-La(DMBA)3 with 3 equiv of N,N′-diisopropylcarbodiimide
in THF at ambient temperature (Scheme 1). Over the course
of 12 h, this reaction underwent a color change from orange-
red to golden yellow. The product was isolated from a
concentrated solution of diethyl ether as a microcrystalline
powder. Its NMR spectrum at ambient temperature was broad
and uninterpretable, indicating significant fluxionality. When
the temperature was raised to 78 °C, the spectrum sharpened
and was consistent with the insertion product 1. We attribute
the fluxional behavior at ambient temperature to slow
intramolecular ligand exchange processes in which the NMe2
unit is transiently coordinated to the metal center instead of
one of the amidinate nitrogen donor atoms. The overall
composition was further supported by elemental analysis data.
Two related yttrium complexes (2 and 3; Scheme 1) were
prepared in a manner similar to that used for 1. As in the
previous case, each of these two complexes exhibited fluxional
NMR spectra at room temperature that sharpened nicely at
elevated temperatures. Thus, we assigned 2 and 3 structures
analogous to that of 1, with compositions that were confirmed
by elemental analysis data. Furthermore, for the cyclohexyl
derivative (3), we were able to obtain X-ray-quality crystals
from a concentrated solution of pentane at room temperature.
The X-ray structure of 3 revealed a homoleptic tris-amidinate
complex (Figure 1). To accurately describe the geometry of 3,
the torsion angle N1−Q1−Q2−N2, where Q1 and Q2 are
centroids formed by the N1N4N7 and N2N5N8 planes from
Figure 1, was determined. A perfect trigonal prism and
octahedron will have torsion angles of 0 and 60°, respectively.
In the case of 3, the torsion angle N1−Q1−Q2−N2 is 28.15°
and compares well to those of other yttrium guanidinates:
Y[(NiPr)2CNMe2]3 (20.77°) and Y[(NiPr)2CNEt2]3
(21.43°).40 The Ln−N bond distances vary from 2.371(3) to
2.405(4) Å and are also quite comparable to those of other
amidinate and guanidinate complexes: Y2[Me3SiNC(Ph)N-
(CH2)3NC(Ph)NSiMe3]2 (2.307(2)−2.354(2) Å), Y[tBuNC-
Figure 1. ORTEP diagram of 3, with cyclohexyl groups from two
ligands removed for clarity (thermal ellipsoids at 30% probability).
Selected bond lengths (Å) and angles (deg): Y1−N1 = 2.393(3), Y1−
N2 = 2.383(3); N1−Y1−N2 = 55.8(1).
(CH3)NtBu]3 (2.379(3)−2.389(3) Å), Y[(NiPr)2CNMe2]3
(2.362(2)−2.373(2) Å), and (C5H5)2Y[iPrNC(NiPr2)NiPr]
(2.316(3)−2.321(3) Å).40−43
Further derivatives of these insertion products were explored
through two additional reactants: bis(trimethylsilyl)-
carbodiimide and N,N′-di-tert-butylcarbodiimide. The latter
showed no insertion into the Ln−C bond for either La or Y
even at elevated temperatures, while the former inserted only 1
equiv of the carbodiimide, yielding complex 4 (Ln = Y)
(Scheme 2). In the NMR spectrum of 4, the benzyl amidinate
Scheme 2. Synthesis of N,N-Dimethylbenzylamine
Amidinate 4 (R = SiMe3)
contained three aryl resonances (7.47, 7.20, and 7.09 ppm) that
were shifted significantly from those of the phenyl group of the
dimethylbenzylamine ligand (7.24, 6.64, and 6.25 ppm). Also,
the methine hydrogen of the newly formed amidinate ligand
4
displayed a doublet with JY−H = 1.9 Hz, while the methine of
the DMBA ligand was a broad singlet. The 13C{1H} NMR of 4
3
displayed two doublets with a coupling constant of JY−C = 4.8
Hz for the methine carbon of the amidinate ligand and 1JY−C
=
6.7 Hz for the methine carbon of the dimethylbenzylamine
B
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ligand. These values are well within the wide range of coupling
constants observed previously for yttrium nonmetallocene
complexes.44,45 The composition of 4 was also confirmed by
X-ray crystallography, verifying the presence of one amidinate
and two DMBA ligands bound to yttrium (Figure 2).
various control experiments. Attempted hydrophosphination
with omission of α-La(DMBA)3 resulted in no hydro-
phosphination product, even after the reaction mixture was
heated to 90 °C for 48 h. To investigate the role of general
Lewis or Brønsted acids, we substituted catalytic quantities of
LaCl3 or triflic acid, respectively. Use of LaCl3 resulted in no
change to the starting materials, while triflic acid yielded at least
three uncharacterized products, none of which had NMR
spectra corresponding to the desired hydrophosphination
products.
Prior to full-scale catalytic screening, we additionally
investigated a series of NMR-scale catalyses using [D8]THF,
in order to determine the optimal conditions for this reaction.
There was a distinct color change upon addition of N,N′-
diisopropylcarbodiimide to the mixture of α-La(DMBA)3 and
1
diphenylphosphine at room temperature. After 10 min, H
NMR spectroscopy indicated that the reaction was >90%
complete. For this and various other heterocumulenes, it was
found that the reaction was essentially complete after 6 h at
room temperature in THF. Noncoordinating reaction solvents
such as C6D6 and C7D8 were screened, but no catalytic activity
was observed. Alternate lanthanide complexes, such as α-
Y(DMBA)3 and α-Ce(DMBA)3, demonstrated moderate
catalytic activity (42% and 40% with diisopropylcarbodiimide,
respectively), but both proved to be inferior to α-La(DMBA)3.
This was attributed to the decomposition of α-Y(DMBA)3 and
α-Ce(DMBA)3 in THF, as noted in our previous report.39
To further develop the substrate scope of this catalytic
reaction, hydrophosphination of a wide range of heterocumu-
lenes was undertaken (Table 1). Additionally, a few
commercially available phosphines were investigated. Hydro-
phosphination of unhindered carbodiimides was very efficient,
and the resulting phosphaguanidines (6a,b) were isolated in
excellent yields. In contrast, attempted hydrophosphination of
N,N′-di-tert-butylcarbodiimide with diphenylphosphine did not
result in production of the desired phosphaguanidine; instead,
only starting materials were observed. This is consistent with
the stoichiometric insertion results, where N,N′-di-tert-
butylcarbodiimide was unable to insert because of the larger
steric bulk of the tert-butyl groups. The hydrophosphination
reaction also worked well with isocyanates and isothiocyanates,
and it was tolerant of both electron-withdrawing and electron-
donating nitrogen substituents on these heterocumulenes (6c−
l). In fact, for most of the isocyanates, NMR spectroscopic
observation of the crude reaction products indicated virtually
quantitative conversion to the desired phosphaureas. The
reduced overall yield is generally reflective of losses upon
isolation and purification. A decrease in reaction yield with 1-
adamantyl isocyanate can be attributed to the larger steric bulk
of the adamantyl group, hindering insertion into the La−
phosphide bond and consequently reducing conversion to the
product. Hydrophosphination of the slightly larger tert-butyl
isocyanate was even worse, with the desired phosphaurea
compound afforded in very low yield (<20%), again
demonstrating the deleterious effect of steric hindrance on
this reaction. Furthermore, scale-up of this reaction with lower
catalyst loading (1 mol %) was successful, giving gram-scale
isolated yields of product 6i (930 mg; 72% yield), although the
reaction times were longer (7 days).
Figure 2. ORTEP diagram of 4 (thermal ellipsoids at 30%
probability). Selected bond lengths (Å) and angles (deg): Y1−C17
= 2.490(3), Y1−C26 = 2.470(3), Y1−N2 = 2.377(2), Y1−N3 =
2.367(2), Y1−N4 = 2.487(3), Y1−N5 = 2.477(2), C16−N2 =
1.332(4), C16−N3 = 1.326(4); N2−Y1−N3 = 57.57(8), N2−C16−
N3 = 118.5(3).
In a recent report, Hou and co-workers demonstrated that
[{Me2Si(C5Me5)(NC6H2Me3-2,4,6)}La(CH2C6H4NMe2-o)-
(thf)] functioned as a useful precatalyst for the hydro-
phosphination of a variety of carbodiimides at elevated
temperatures (80 °C).23 Given the results involving carbodii-
mide insertion reactions presented herein and our previous
investigation into protonolysis reactions of α-Ln(DMBA)3,39
we felt that these new complexes were perfectly suited for use
in catalytic hydrophosphination reactions. To test this
hypothesis, we first added N,N′-diisopropylcarbodiimide to a
solution of α-La(DMBA)3 (5 mol %) and THF at room
temperature, followed by the addition of 1 equiv of
diphenylphosphine. While we did observe excellent conversion
to the phosphaguanidine product, in accordance with the
aforementioned results, this product was contaminated with the
amidine iPrNC(NHiPr)CHPhNMe2, which was likely
formed by insertion of the carbodiimide into the La−DMBA
bond, followed by subsequent protonolysis by Ph2PH. Thus,
this order of addition of reactants is limited to a maximum yield
of 85% due to the initial formation of the insertion product 1.
Therefore, the order of addition was reversed in our subsequent
experiments; that is, diphenylphosphine was added to α-
La(DMBA)3 followed by the N,N′-diisopropylcarbodiimide.
Additionally, 1.15 equiv of Ph2PH was used to offset the
amount consumed in activation of the precatalyst. Using this
reversed order of addition, we found that DMBA-H was
produced (via initial protonolysis of α-La(DMBA)3 by Ph2PH)
instead of the amidine observed previously, and this byproduct
was much more easily removed from the desired phosphagua-
nidines, improving isolated yields greatly. In order to confirm
that this reaction required a catalyst to proceed, we investigated
The acidity of the phosphine employed was also found to
significantly affect the catalysis. Attempted hydrophosphination
of N,N′-diisopropylcarbodiimide with di-tert-butylphosphine
gave no product even on heating to 80 °C for 36 h. Small
C
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a
Table 1. Catalytic Addition of Phosphines to Heterocumulenes
a
b
c
Conditions: phosphine (1.15 mmol), heterocumulene (1.00 mmol), catalyst (0.05 mmol), THF (3 mL). Isolated yield. Reaction mixture stirred
d
at 55 °C. Product isolated as a 3:1 ratio of phosphaurea 6h and trimerized isocyanate.
amounts of (4-MeOC6H4)2PH and di-p-tolylphosphine were
obtained from commercial sources for comparison. In both
cases, the related phosphaureas (6m,n) were produced and
isolated in yields very similar to those obtained with the
unsubstituted diphenylphosphine, indicating little or no
sensitivity to electronic effects at this position.
To gain insight into the possible catalysis mechanism, α-
La(DMBA)3 was treated with 3 equiv of diphenylphosphine in
THF (15 mL), followed by 3 equiv of N,N′-diisopropylcarbo-
diimide (Scheme 3). After removal of THF under vacuum, the
mixture was triturated with pentane (10 mL), washed twice
with pentane (12 mL) at −78 °C, and dried under vacuum.
The resulting product (5) was then recrystallized from a
concentrated solution of toluene at room temperature. Its X-ray
crystal structure revealed a homoleptic complex in which three
phosphaguanidinate ligands are bound to the metal center
through their chelating nitrogen atoms (Figure 3). The La−N
bond distances of 5 (2.502(1)−2.566(1) Å) are slightly shorter
than those found in [{Me2Si(C5Me4)(NC6H2Me3-2,4,6)}La-
{iPrNC(PPh2)NiPr}(OEt2)] (2.557(2) and 2.570(2) Å)23 and
D
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Scheme 3. Synthesis of Homoleptic Lanthanum Phosphaguanidinate (5)
Scheme 4. Proposed Catalytic Cycle for the
Hydrophosphination of N,N′-Diisopropylcarbodiimide
attempts to isolate the putative catalyst via various synthetic
routes have not been successful, and to our knowledge
complexes of the form LnLa(PPh2)3 have not been reported
(L = neutral donor ligand). The catalyst activation step
produces either DMBA-H or the protonated product after
heterocumulene insertion into the La−DMBA bond. In either
case, the functional catalyst involves a La−PR2 active moiety.
Overall, the catalysis proceeds via insertion of the hetero-
cumulene into a La−PR2 bond, followed by protonolysis to
yield the hydrophosphination product and regenerate the active
species. As noted above, di-tert-butylphosphine was not a useful
hydrophosphination reagent. Given its much lower acidity,48 it
is likely that the di-tert-butylphosphine is unable to protonate
off the product phosphaguanidinate ligand, preventing catalytic
turnover, while the other phosphine substrates tested were
acidic enough to effect this step in the catalysis.
Figure 3. ORTEP diagram of 5 (thermal ellipsoids at 30%
probability). Selected bond lengths (Å) and angles (deg): La1−N1
= 2.566(1), La1−N2 = 2.502(1), C1−N1 = 1.328(2), C1−N2 =
1.338(2), P1−C1 = 1.907(2), P1−C2 = 1.834(2), P1−C8 = 1.837(2),
N1−C14 = 1.463(2), N2−C17 = 1.467(2); N1−La1−N2 = 52.87(4),
N1−C1−N2 = 115.6(1), C2−P1−C8 = 106.63(7).
marginally longer than the amidinate bond distances of
[La{MeC(NCy)2}3] (2.493(4) and 2.501(4) Å).23,46 Complex
5 proved to be a competent hydrophosphination catalyst. For
example, the hydrophosphination of N,N′-diisopropylcarbodii-
mide with diphenylphosphine using a catalytic amount of 5 (5
mol %) yielded the phosphaguanidine 6a (93%), supporting 5
as a possible catalytic intermediate.
Given the results discussed throughout this report, we
propose the mechanism shown in Scheme 4 for this catalytic
reaction. Transformation of the α-La(DMBA)3 complex to the
active catalyst is postulated to occur via protonolysis by the
phosphine substrate, giving a THF-solvated lanthanum
diphenylphosphide complex, most likely La(PPh2)3(THF)n.
The much higher catalytic efficiency observed in coordinating
solvents is consistent with the formation of a catalytic species
that requires donor ligands to inhibit catalyst decomposition
pathways. Previous reports note that tris-phosphido lanthanide-
(III) complexes are notoriously difficult to isolate cleanly, often
being formed as “ate” salts, a problem commonly experienced
in early-transition-metal and lanthanide chemistry.47 Our
CONCLUSIONS
■
We have broadened the reactivity scope of the α-metalated
N,N-dimethylbenzylamine rare-earth-metal complexes α-La-
(DMBA)3 and α-Y(DMBA)3. Both complexes have been
shown to undergo triple-insertion reactions to form homoleptic
amidinate and phosphaguanidinate complexes (1−5). Addi-
tionally, the La and Y homoleptic complexes serve as useful
catalytic precursors for the addition of a P−H bond across the
CN bond of heterocumulenes. α-La(DMBA)3 demonstrated
excellent catalytic activity at room temperature for the
hydrophosphination of a wide variety of heterocumulenes. It
showed broad tolerance to electron-donating and electron-
withdrawing substituents on aryl isocyanates. The catalytic
effectiveness appeared to be dependent on both the acidity of
the phosphine and the steric bulk of the heterocumulene. The
catalytic mechanism likely begins with formation of a metal
phosphide, followed by insertion of a heterocumulene, and
subsequent protonation yields the hydrophosphination prod-
E
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640 (m). Anal. Calcd for C48H78LaN9: C, 62.66; H, 8.54; N, 13.70.
Found: C, 61.60; H, 8.59; N, 13.35. Mp: 187 °C dec.
uct. The most important aspect of the results reported herein is
the development of a new hydrophosphination catalyst with
broad substrate tolerance that functions effectively at ambient
temperature. Further catalytic studies involving catalytic
hydrophosphination of α,β-unsaturated ketones and allenes
will be investigated in due course.
Y[iPrNC(DMBA)NiPr]3 (2). An oven-dried Schlenk tube was
charged with α-Y(DMBA)3 (282 mg, 0.575 mmol). Toluene (15
mL) was added to the α-Y(DMBA)3, followed by diisopropylcarbo-
diimide (276 μL, 224 mg, 1.77 mmol). The mixture was stirred at
room temperature for 12 h. The toluene was removed under vacuum,
the solid was extracted with pentane, and the extract was filtered and
concentrated. The flask was placed in a freezer at −20 °C to yield a
white precipitate after 3 days (208 mg, 42%). 1H NMR (C7D8, 78 °C):
EXPERIMENTAL SECTION
■
General Considerations. Compounds 1−5 and 6a−n were
prepared using standard Schlenk and drybox techniques. Lanthanum-
(III) chloride and yttrium(III) chloride were purchased from Strem
and used without further purification. α-La(DMBA)3 and α-
Y(DMBA)3 were synthesized as previously described.39 Diphenyl-
phosphine was synthesized according to the literature report for
diisopropylphosphine, as previously described.49 Diisopropylcarbodii-
mide, cyclohexyl isocyanate, phenyl isothiocyanate, and 1-naphthyl
isocyanate were purchased from Acros, dried over 4 Å molecular
sieves, freeze−pump−thawed three times, distilled, and stored under
nitrogen. Dicyclohexylcarbodiimide was purchased from Acros and
sublimed. Phenyl isocyanate was purchased from Aldrich, dried over 4
Å molecular sieves, freeze−pump−thawed three times, distilled, and
stored under nitrogen. 1-Adamantyl isocyanate, 4-fluorophenyl
isocyanate, 4-chlorophenyl isocyanate, 4-bromophenyl isocyanate, 4-
(trifluoromethyl)phenyl isocyanate, 4-methoxyphenyl isocyanate, and
di-p-methoxyphenyl phosphine were purchased from Aldrich, stored
under nitrogen, and used without further purification. Di-p-
tolylphosphine was purchased from Strem as a 10% by mass solution
in hexane, and the hexane was removed in vacuo prior to use. C6D6
and C7D8 were purchased from Cambridge Isotope Laboratories and
were vacuum-transferred from sodium/benzophenone ketyl and
degassed with three freeze−evacuate−thaw cycles. C4D8O was
purchased from Cambridge Isotope Laboratories and was vacuum-
transferred from 4 Å molecular sieves and degassed with three freeze−
evacuate−thaw cycles. All other solvents were purchased from either
VWR or Fisher. Pentane, methylene chloride, and toluene were
purified by passage through columns of activated 4 Å molecular sieves
and degassed prior to use. Diethyl ether was purified by passage
through a column of activated alumina and degassed prior to use.
Tetrahydrofuran was dried over sodium/benzophenone ketyl and
distilled prior to use. All 1H, 13C, and 31P NMR data were obtained on
a 400 MHz VXRS, 600 MHz Inova, or 600 MHz Avance III Bruker
3
3
δ 7.45 (d, JH3−H = 7.2 Hz, 6H, o-H), 7.11 (t, JH−H = 7.2 Hz, 6H, m-
H), 7.01 (t, JH−H = 7.2 Hz, 3H, p-H), 4.54 (bs, 3H, CH(C6H5)-
(NMe2)), 4.50−4.30 (m, 6H, CH(CH3)2), 2.27 (s, 18H, CH(C6H5)-
(NMe2)), 1.39−1.29 (m, 9H, CH(CH3)2), 1.09−1.00 (m, 18H,
CH(CH3)2), 0.83−0.79 (m, 9H, CH(CH3)2). 13C{1H} NMR (C7D8,
78 °C): δ 173.33, 140.31, 129.53, 128.35, 126.58, 69.53, 46.55, 45.39,
27.67. IR (Nujol, cm−1): 2896 (s), 2627 (s), 2352 (w), 1646 (w), 1595
(m), 1461 (s), 1337 (s), 1259 (s), 1189 (s), 1125 (s), 1093 (m), 1051
(s), 1018 (s), 940 (m), 917 (w), 894 (s), 867 (m), 839 (s), 816 (m),
738 (s), 701 (s), 650 (w). Anal. Calcd for C48H78N9Y: C, 66.26; H,
9.04; N, 14.49. Found: C, 65.75; H, 9.13; N, 14.19. Mp: 180 °C dec.
Y[CyNC(DMBA)NCy]3 (3). An oven-dried Schlenk tube was
charged with α-Y(DMBA)3 (266 mg, 0.540 mmol). Toluene (15
mL) was added to the α-Y(DMBA)3, followed by dicyclohexylcarbo-
diimide (346 mg, 1.68 mmol). The mixture was stirred at room
temperature for 36 h. The toluene was removed under vacuum, the
solid was extracted with pentane, and the extract was filtered and
concentrated. Colorless crystals grew from a concentrated pentane
1
solution at room temperature (388 mg, 65%). H NMR (C7D8, 78
°C): δ 7.65−7.57 (m, 6H, o-H), 7.29−7.18 (m, 6H, m-H), 7.07−7.02
(m, 3H, p-H), 4.74−4.70 (m, 3H, CH(C6H5)(NMe2)), 4.08 (bs, 6H,
CH-cyclohexyl), 2.38−2.35 (m, 18H, CH(C6H5)(NMe2)), 1.80−1.25
(m, 60H, CH2-cyclohexyl). 13C{1H} NMR (C7D8, 78 °C): δ 173.16,
140.53, 128.30, 126.63, 126.32, 68.23, 55.67, 45.44, 35.39, 32.40,
29.84. IR (Nujol, cm−1): 2884 (s), 2758 (s), 2116 (s), 1598 (m), 1446
(s), 1344 (s), 1260 (s), 1176 (s), 1130 (s), 1024 (s), 990 (s), 957 (w),
923 (m), 889 (s), 843 (m), 830 (m), 805 (m), 741 (s), 699 (s), 623
(m). Anal. Calcd for C66H102N9Y: C, 71.38; H, 9.26; N, 11.35. Found:
C, 71.05; H, 9.40; N, 10.96. Mp: 178−181 °C.
Y[Me3SiNC(DMBA)NSiMe3](DMBA)2 (4). An oven-dried Schlenk
tube was charged with α-Y(DMBA)3 (368 mg, 0.749 mmol). Toluene
(15 mL) was added, followed by bis(trimethylsilyl)carbodiimide (188
μL, 154 mg, 0.826 mmol). The mixture was stirred at room
temperature for 48 h. The toluene was removed under vacuum, the
solid was extracted with hot diethyl ether, and the extract was filtered
and concentrated. The flask was placed in a freezer at −20 °C to yield
1
spectrometer. H NMR shifts given were referenced internally to the
residual solvent peaks at δ 7.16 ppm (C6D5H), 2.08 ppm (C7D7H),
and 3.58 ppm (C4D7HO). 13C NMR shifts given were referenced
internally to the residual peaks at δ 128.0 ppm (C6D6) and 20.4 ppm
(C7D8). Phosphorus NMR spectra were externally referenced to 0.00
ppm with 5% H3PO4 in D2O. IR samples were prepared as Nujol mulls
and taken between KBr plates on a Perkin-Elmer XTL FTIR
spectrophotometer. Melting points were observed on a capillary
Mel-Temp apparatus in sealed capillary tubes under nitrogen and are
uncorrected. Elemental analyses were determined by Atlantic Micro-
labs, Inc., Norcross, GA. Single-crystal X-ray structure determinations
were performed at The University of Toledo.
1
a yellow precipitate after 3 days (429 mg, 84%). H NMR (C6D6, 23
°C): δ 7.47 (d, 3JH−H = 7.4 Hz, 2H, o-H(amidinate)), 7.24 (t, 3JH−H
=
3
7.0 Hz, 4H, m-H(DMBA)), 7.20 (t, JH−H = 7.4 Hz, 2H, m-
H(amidinate)), 7.09 (t, 3JH−H = 7.4 Hz, 1H, p-H(amidinate)), 6.64 (t,
3
3JH−H = 7.0 Hz, 2H, p-H(DMBA)), 6.25 (d, JH−H = 7.0 Hz, 4H, o-
4
H(DMBA)), 4.16 (d, JY−H = 1.9 Hz, 1H, CH(amidinate)), 3.53 (s,
2H, CH(DMBA)), 2.20 (bs, 12H, NMe2(DMBA)), 2.09 (s, 6H,
NMe2(amidinate)), 0.100 (s, 18H, SiMe3). 13C{1H} NMR (C6D6, 23
La[iPrNC(DMBA)NiPr]3 (1). An oven-dried Schlenk tube was
charged with α-La(DMBA)3 (400 mg, 0.739 mmol). THF (15 mL)
was added to the α-La(DMBA)3, followed by diisopropylcarbodiimide
(355 μL, 0.288 g, 2.28 mmol). The mixture was stirred at room
temperature for 12 h. The THF was removed under vacuum, the solid
was extracted with diethyl ether, and the extract was filtered and
concentrated. The flask was placed in a freezer at −20 °C to yield a
white precipitate after 3 days (516 mg, 76%). 1H NMR (C7D8, 78 °C):
δ 7.48−7.44 (m, 6H, o-H), 7.41 (t, 3JH−H = 6.4 Hz, 6H, m-H), 7.00 (t,
3JH−H = 6.4 Hz, 3H, p-H), 4.49 (s, 3H, CH(C6H5)(NMe2)), 4.38 (bs,
6H, CH(CH3)2), 2.33 (s, 18H, CH(C6H5)(NMe2)), 1.33−1.22 (m,
18H, CH(CH3)2), 0.93−0.85 (m, 18H, CH(CH3)2). 13C{1H} NMR
(C7D8, 78 °C): δ 171.37, 140.96, 129.12, 128.29, 126.34, 68.85, 46.88,
45.15, 27.37. IR (Nujol, cm−1): 2924 (s), 2767 (s), 2592 (m), 1645
(w), 1600 (m), 1471 (s), 1318 (s), 1254 (s), 1180 (s), 1120 (s), 1023
(s), 940 (m), 894 (s), 862 (m), 839 (m), 811 (m), 737 (s), 701 (s),
2
°C): δ 177.89 (d, JY−C = 4.4 Hz, amidinate), 139.98, 137.30, 131.99,
1
131.91, 128.45, 128.41, 114.73, 110.14, 80.08 (d, JY−C = 6.7 Hz,
3
DMBA), 77.61 (d, JY−C = 4.8 Hz, amidinate), 46.11, 41.07, 3.48. IR
(Nujol, cm−1): 2928 (s), 2845 (s), 2129 (w), 1598 (m), 1535 (w),
1463 (s), 1374 (m), 1307 (w), 1245 (m), 1177 (w), 1151 (w), 1042
(w), 1011 (m), 975 (w), 868 (w), 835 (s), 731 (m), 695 (m), 674 (w),
638 (w), 607 (w). Anal. Calcd for C34H54N5Si2Y: C, 60.24; H, 8.03; N,
10.33. Found: C, 57.96; H, 7.84; N, 9.93. Mp: 149−153 °C.
La[iPrNC(PPh2)NiPr]3 (5). An oven-dried Schlenk tube was
charged with α-La(DMBA)3 (542 mg, 1.00 mmol). THF (15 mL)
was added, followed by diphenylphosphine (568 mg, 3.05 mmol). The
mixture was stirred until the solution was ruby red. A second oven-
dried Schlenk tube was charged with diisopropylcarbodiimide (472 μL,
385 mg, 3.05 mmol) and THF (5 mL), which was then added to the
initial reaction mixture. The reaction mixture was stirred at room
temperature overnight to yield a yellow solution. The THF was
F
dx.doi.org/10.1021/om300807k | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
3
removed under vacuum, and the mixture was triturated with pentane
(10 mL) to yield a yellow precipitate. The precipitate was washed
twice with pentane (12 mL) at −78 °C and dried under vacuum. The
solid was dissolved in toluene (15 mL). Colorless X-ray-quality crystals
were grown at room temperature from a concentrated solution of
6H, Ph-P), 5.49 (bd, JH−H = 6.0 Hz, 1H, N-H), 3.96−3.95 (m, 1H,
CH), 1.65−1.62 (m, 2H, CH2), 1.29−1.21 (m, 2H, CH2), 1.04−0.98
(m, 2H, CH2), 0.80−0.78 (m, 2H, CH2), 0.71−0.69 (m, 2H, CH2).
13C{1H} NMR (C6D6, 23 °C): δ 174.92 (d, JP−C = 12.3 Hz), 135.39
1
1
2
(d, JP−C = 12.7 Hz), 134.65 (d, JP−C = 18.8 Hz), 129.57, 129.00 (d,
3JP−C = 7.0 Hz), 48.69, 32.82, 25.58, 24.70. 31P{1H} NMR (C6D6, 23
°C): δ −3.35. IR (Nujol, cm−1): 3251 (m), 2918 (s), 2285 (m), 1974
(w), 1957 (w), 1898 (w), 1883 (w), 1624 (s), 1497 (s), 1438 (s), 1370
(m), 1337 (m), 1303 (m), 1256 (m), 1218 (s), 1185 (m), 1151 (m),
1092 (m), 1024 (m), 999 (m), 919 (w), 885 (m), 839 (m), 805 (w),
739 (w), 746 (s), 695 (s). Anal. Calcd for C19H22NOP: C, 73.29; H,
7.12; N, 4.50. Found: C, 71.97; H, 7.12; N, 4.39. HRMS: calcd m/z
312.1517 for C19H23NOP [M + H]+, measd 312.1522.
1
3
toluene (697 mg, 65%). H NMR (C6D6, 23 °C): δ 7.72 (t, JH−H
=
3JP−H = 7.2 Hz, 12H, o-H), 7.14 (t, 3JH−H = 7.2 Hz, 12H, m-H), 7.06 (t,
3JH−H = 7.2 Hz, 6H, p-H), 4.35 (sept, 3JH−H = 6.0 Hz, 6H, CH(CH3)2),
1.17 (bs, 36H, CH(CH3)2). 13C{1H} NMR (C6D6, 23 °C): δ 171.52
1
1
2
(d, JP−C = 54.6 Hz), 135.65 (d, JP−C = 28.6 Hz), 134.29 (d, JP−C
=
3
4
19.8 Hz), 132.38 (d, JP−C = 17.8 Hz), 128.70 (d, JP−C = 5.5 Hz),
49.88 (d, JP−C = 21.1 Hz), 26.87. 31P{1H} NMR (C6D6, 23 °C): δ
3
−18.86. IR (Nujol, cm−1): 2918 (s), 2842 (s), 1948 (w), 1581 (s),
1433 (s), 1362 (s), 1311 (s), 1164 (s), 1117 (s), 1062 (m), 990 (s),
940 (w), 910 (w), 872 (w), 843 (w), 813 (w), 737 (s), 691 (s), 636
(s). Anal. Calcd for C57H72LaN6P3: C, 63.80; H, 6.76; N, 7.83. Found:
C, 63.95; H, 6.72; N, 8.02. Mp: 201−204 °C.
OC(PPh2)(NHAd) (6e). Method C. White solid (138 mg, 38%).
1H NMR (C6D6, 23 °C): δ 7.69−7.66 (m, 4H, Ph-P), 7.11−7.08 (m,
4H, Ph-P), 7.06−7.04 (m, 2H, Ph-P), 5.35 (bs, 1H, N-H), 1.86 (bs,
6H, Ad-H), 1.79 (bs, 3H, Ad-H), 1.44−1.40 (m, 6H, Ad-H). 13C{1H}
NMR (C6D6, 23 °C): δ 174.86 (d, 1JP−C = 13.6 Hz), 135.69 (d, 1JP−C
=
General Procedures for the Hydrophosphination of Hetero-
cumulenes. Method A. An oven-dried Schlenk tube was charged with
α-La(DMBA)3 (27.0 mg, 0.0500 mmol) and THF (2 mL).
Diphenylphosphine (214 mg, 1.15 mmol) and THF (1 mL) were
added. The mixture was stirred until the solution turned ruby red. The
carbodiimide (1.00 mmol) was then added. The mixture was stirred
for 6 h at room temperature. The THF was removed under vacuum
and triturated with 3 mL of pentane. The solid was extracted with
pentane, filtered, and concentrated. The Schlenk tube was placed in a
freezer at −20 °C to yield a white solid. Spectroscopic data for 6a,b
matched those of previously reported material.23
Method B. An oven-dried Schlenk tube was charged with α-
La(DMBA)3 (27.0 mg, 0.0500 mmol) and THF (2 mL). The
phosphine (1.15 mmol) and THF (1 mL) were added to the reaction
mixture. The mixture was stirred until the solution turned ruby red.
The heterocumulene (1.00 mmol) was then added. The mixture was
stirred for 6 h at room temperature. The THF was removed under
vacuum and triturated with 3 mL of pentane. The solid was washed
with cold pentane (5 mL), filtered, and dried under vacuum, yielding a
white or yellow precipitate.
2
3
12.1 Hz), 134.53 (d, JP−C = 18.1 Hz), 129.34, 128.92 (d, JP−C = 6.0
Hz), 53.33, 41.66, 36.35, 29.74. 31P{1H} NMR (C6D6, 23 °C): δ
−2.20. IR (Nujol, cm−1): 3258 (m), 2933 (s), 2852 (s), 1625 (s), 1491
(s), 1455 (s), 1432 (s), 1375 (m), 1352 (m), 1308 (m), 1290 (m),
1276 (m), 1205 (s), 1182 (m), 1088 (m), 1026 (w), 999 (w), 941 (w),
887 (w), 856 (w), 802 (w), 748 (s), 722 (w), 695 (s). Anal. Calcd for
C23H26NOP: C, 76.01; H, 7.21; N, 3.85. Found: C, 74.50; H, 7.41; N,
4.17. HRMS: calcd m/z 364.1830 for C23H27NOP [M + H]+, measd
364.1833.
OC(PPh2)(NH-1-Naph) (6f). Method C. White solid (271 mg,
1
3
76%). H NMR (C6D6, 23 °C): δ 8.70 (d, JH−H = 8.4 Hz, 1H, 2-
3
Naph), 7.83 (s, 1H, N-H), 7.61 (m, 4H, Ph-P), 7.52 (d, JH−H = 8.4
Hz, 1H, 8-Naph), 7.34 (d, 3JH−H = 8.4 Hz, 1H, 4-Naph), 7.21 (t, 3JH−H
= 8.4 Hz, 1H, 3-Naph), 7.13 (t, 3JH−H = 8.4 Hz, 1H, 7-Naph), 7.06 (m,
3
7H, Ph-P and 6-Naph), 6.79 (d, JH−H = 8.4 Hz, 1H, 5-Naph).
13C{1H} NMR (C6D6, 23 °C): δ 175.46 (d, JP−C = 15.2 Hz), 134.82
1
2
1
(d, JP−C = 19.1 Hz), 134.39, 134.29 (d, JP−C = 12.8 Hz), 132.60 (d,
3JP−C = 2.1 Hz), 129.88, 129.29 (d, JP−C = 7.1 Hz), 129.14, 128.68,
3
126.29, 126.06, 125.80, 125.20, 119.54, 118.41. 31P{1H} NMR (C6D6,
23 °C): δ −0.36. IR (Nujol, cm−1): 3257 (s), 2936 (s), 2849 (s), 1717
(w), 1630 (s), 1530 (s), 1469 (s), 1430 (s), 1400 (m), 1378 (m), 1339
(s), 1265 (m), 1248 (s), 1196 (s), 1161 (s), 1083 (w), 1026 (w), 952
(w), 909 (w), 888 (w), 856 (w), 793 (s), 771 (s), 740 (s), 692 (s), 644
(m). Anal. Calcd for C23H18NOP: C, 77.74; H, 5.11; N, 3.94. Found:
C, 75.43; H, 5.08; N, 4.48. HRMS: calcd m/z 356.1204 for
C23H19NOP [M + H]+, measd 356.1206.
Method C. An oven-dried Schlenk tube was charged with α-
La(DMBA)3 (27.0 mg, 0.0500 mmol) and THF (2 mL).
Diphenylphosphine (214 mg, 1.15 mmol) and THF (1 mL) were
added to the reaction mixture. The mixture was stirred until the
solution turned ruby red. The isocyanate (1.00 mmol) was then added.
The mixture was stirred for 12 h at 55 °C. The THF was removed
under vacuum and triturated with 3 mL of pentane. The solid was
washed with pentane (5 mL), filtered, and dried under vacuum,
yielding a white precipitate.
SC(PPh2)(NHPh) (6g). Method B. Yellow solid (292 mg, 91%).
1H NMR (C6D6, 23 °C): δ 8.67 (bs, 1H, N-H), 7.67 (d, JH−H = 7.8
3
iPrNC(PPh2)(NHiPr) (6a).23 Method A. White solid (290 mg,
93%). Anal. Calcd for C19H25N2P: C, 73.05; H, 8.07; N, 8.97. Found:
C, 71.37; H, 7.98; N, 8.85. HRMS: calcd m/z 313.1834 for C19H26N2P
[M + H]+, measd 313.1825.
Hz, 2H, o-H), 7.49−7.46 (m, 4H, Ph-P), 7.03−7.00 (m, 6H, Ph-P),
6.96 (t, 3JH−H = 7.8 Hz, 2H, m-H), 6.86 (t, 3JH−H = 7.8 Hz, 1H, p-H).
13C{1H} NMR (C6D6, 23 °C): δ 206.39 (d, 1JP−C = 39.3 Hz), 139.78,
1
2
CyNC(PPh2)(NHCy) (6b).23 Method A. White solid (290 mg,
74%). Anal. Calcd for C25H33N2P: C, 76.50; H, 8.47; N, 7.14. Found:
C, 74.81; H, 8.56; N, 6.93. HRMS: calcd m/z 393.2460 for C25H34N2P
[M + H]+, measd 393.2456.
135.80 (d, JP−C = 17.0 Hz), 134.74 (d, JP−C = 21.1 Hz), 130.07,
129.34 (d, JP−C = 6.0 Hz), 129.01, 126.60, 121.80. 31P{1H} NMR
3
(C6D6, 23 °C): δ 20.86. IR (Nujol, cm−1): 3300 (m), 2953 (s), 2857
(s), 2284 (w), 1960 (w), 1886 (w), 1821 (w), 1660 (w), 1595 (m),
1521 (m), 1465 (s), 1443 (s), 1373 (s), 1204 (m), 1152 (m), 1083
(m), 1026 (m), 996 (m), 978 (m), 926 (w), 905 (m), 852 (w), 796
(m), 722 (s), 692 (s). Anal. Calcd for C19H16NPS: C, 71.01; H, 5.02;
N, 4.36. Found: C, 68.58; H, 5.27; N, 3.99. HRMS: calcd m/z
322.0819 for C19H17NPS [M + H]+, measd 322.0811.
OC(PPh2)(NHPh) (6c). Method B. White solid (184 mg, 60%).
1H NMR (C6D6, 23 °C): δ 7.57−7.55 (m, 4H, Ph-P), 7.34 (d, 3JH−H
=
3
7.8 Hz, 2H, o-H), 7.22 (d, JP−H = 8.4 Hz, 1H, N-H), 7.03−7.02 (m,
6H, Ph-P), 6.97 (t, 3JH−H = 7.8 Hz, 2H, m-H), 6.81 (t, 3JH1−H = 7.8 Hz,
1H, p-H). 13C{1H} NMR (C6D6, 23 °C): δ 175.49 (d, JP−C = 15.4
Hz), 149.02, 135.06 (d, 2JP−C = 19.3 Hz), 134.64 (d, 1JP−C = 17.5 Hz),
OC(PPh2){N(H)C6H4F-4} (6h). Method B. White solid in a 3:1
ratio of product and trimerized isocyanate (193 mg, 83%), purified by
passing through a plug of silica gel. 1H NMR (C6D6, 23 °C): δ 7.57−
7.54 (m, 4H, Ph-P), 7.12 (bs, 1H, N-H), 7.09−7.07 (m, 2H, o-H),
3
130.20, 129.61, 129.51 (d, JP−C = 2.9 Hz), 124.87, 119.74. 31P{1H}
NMR (C6D6, 23 °C): δ 0.77. IR (Nujol, cm−1): 3247 (m), 2941 (s),
2843 (s), 1701 (w), 1688 (w), 1590 (m), 1531 (m), 1455 (s), 1433
(s), 1348 (s), 1303 (m), 1236 (m), 1169 (w), 1088 (w), 1066 (w),
1026 (w), 990 (w), 914 (w), 887 (w), 757 (m), 735 (s), 690 (s), 650
(w), 587 (m). Anal. Calcd for C19H16NOP: C, 74.74; H, 5.28; N, 4.59.
Found: C, 70.23; H, 4.89; N, 5.22. HRMS: calcd m/z 306.1048 for
C19H17NOP [M + H]+, measd 306.1041.
7.05−7.04 (m, 6H, Ph-P), 6.60 (t, JF−H = 3JH−H = 9.0 Hz, 2H, m-H).
3
13C{1H} NMR (C6D6, 23 °C): δ 174.94 (d, JP−C = 15.6 Hz), 159.57
1
(d, 1JF−C = 242.0 Hz), 134.66 (d, 2JP−C = 19.7 Hz), 134.39 (br), 134.09
1
3
(d, JP−C = 11.3 Hz), 129.89, 129.13 (d, JP−C = 7.1 Hz), 121.06 (d,
3JF−C = 7.7 Hz), 115.62 (d, 2JF−C = 22.2 Hz). 31P{1H} NMR (C6D6, 23
°C): δ 0.55. IR (Nujol, cm−1): 3210 (m), 2929 (s), 2848 (s), 1881
(w), 1811 (w), 1630 (m), 1605 (m), 1529 (m), 1509 (m), 1464 (m),
OC(PPh2)(NHCy) (6d). Method B. White solid (167 mg, 54%).
1H NMR (C6D6, 23 °C): δ 7.67−7.65 (m, 4H, Ph-P), 7.10−7.06 (m,
G
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1434 (m), 1399 (m), 1379 (m), 1298 (m), 1253 (m), 1208 (m), 1168
(m), 1153 (m), 1097 (m), 1022 (w), 886 (w), 851 (w), 826 (m), 735
(m), 690 (m), 640 (m). HRMS: calcd m/z 324.0954 for C19H16FNOP
[M + H]+, measd 324.0948.
Hz, 4H, o-H), 7.31 (s, 1H, N-H), 7.17 (d, JH−H = 9.6 Hz, 2H, o-H),
7.15 (d, 3JH−H = 9.6 Hz, 2H, m-H), 6.94 (d, 3JH−H = 8.0 Hz, 4H, m-H),
2.01 (s, 6H, CH3). 13C{1H} NMR (C6D6, 23 °C): δ 176.76 (d, 1JP−C
=
3
2
17.3 Hz), 141.15 (d, JP−C = 3.2 Hz), 140.28, 134.82 (d, JP−C = 19.8
Hz), 130.39 (d, 1JP−C = 9.0 Hz), 130.01 (d, 3JP−C = 7.8 Hz), 126.30 (q,
3JF−C = 3.5 Hz), 125.94 (q, 2JF−C = 32.8 Hz), 124.80 (q, 1JF−C = 272.0
Hz), 119.11, 20.74. 31P{1H} NMR (C6D6, 23 °C): δ 0.24. IR (Nujol,
cm−1): 3263 (s), 2925 (s), 2881 (s), 1906 (w), 1632 (s), 1602 (s),
1524 (s), 1459 (s), 1403 (s), 1372 (m), 1312 (s), 1246 (s), 1173 (s),
1147 (s), 1116 (s), 1064 (s), 1012 (m), 964 (w), 903 (m), 838 (m),
799 (m), 751 (w), 712 (m), 630 (m). HRMS: calcd m/z 402.1235 for
C22H20F3NOP [M + H]+, measd 402.1237.
Hydrophosphination Scale-Up Experiment. Method B was
employed with the following chemicals: Ph2PH (810 mg, 4.35 mmol),
4-chlorophenyl isocyanate (580 mg, 3.78 mmol), La(DMBA)3 (22 mg,
0.041 mmol), and THF (7 mL). The reaction mixture was stirred at
ambient temperature for 7 days. After workup product 6i was isolated
(930 mg, 72%), with spectroscopic properties matching those reported
above.
OC(PPh2){N(H)C6H4Cl-4} (6i). Method B. White solid (281 mg,
1
83%). H NMR (C6D6, 23 °C): δ 7.55−7.52 (m, 4H, Ph-P), 7.31 (s,
1H, N-H), 7.08 (d, 3JH−H = 9.0 Hz, 2H, o-H), 7.07−7.04 (m, 6H, Ph-
P), 6.92 (d, 3JH−H = 9.0 Hz, 2H, m-H). 13C{1H} NMR (C6D6, 23 °C):
1
3
δ 175.28 (d, JP−C = 16.1 Hz), 136.80 (d, JP−C = 4.2 Hz), 134.68 (d,
2JP−C = 19.6 Hz), 133.92 (d, 1JP−C = 10.9 Hz), 129.95, 129.49, 129.15
(d, JP−C = 7.6 Hz), 129.08, 120.68. 31P{1H} NMR (C6D6, 23 °C): δ
3
1.00. IR (Nujol, cm−1): 3239 (m), 2935 (s), 2857 (s), 1899 (w), 1690
(w), 1625 (m), 1591 (m), 1525 (m), 1460 (s), 1378 (s), 1300 (s),
1282 (m), 1235 (m), 1169 (m), 1091 (m), 1013 (m), 896 (w), 833
(m), 808 (m), 737 (m), 697 (m), 658 (m). HRMS: calcd m/z
340.0658 for C19H16ClNOP [M + H]+, measd 340.0648.
OC(PPh2){N(H)C6H4Br-4} (6j). Method B. White solid (190 mg,
1
49%). H NMR (C6D6, 23 °C): δ 7.54−7.51 (m, 4H, Ph-P), 7.06 (d,
3JH−H = 8.8 Hz, 2H, o-H), 7.05−7.03 (m, 6H, Ph-P), 7.00 (bs, 1H, N-
H), 6.97 (d, 3JH−H = 8.8 Hz, 2H, m-H). 13C{1H} NMR (C6D6, 23 °C):
1
3
ASSOCIATED CONTENT
* Supporting Information
δ 175.68 (d, JP−C = 16.4 Hz), 137.63 (d, JP−C = 3.9 Hz), 135.06 (d,
2JP−C = 19.6 Hz), 134.27 (d, 1JP−C = 10.9 Hz), 132.43, 130.34, 129.53
■
S
(d, JP−C = 7.6 Hz), 121.38, 117.46. 31P{1H} NMR (C6D6, 23 °C): δ
3
Text, a table, and CIF files giving crystal data, including bond
lengths and angles, and additional crystallographic experimental
information for compounds 3−5. This material is available free
of charge via the Internet at http://pubs.acs.org.
1.28. IR (Nujol, cm−1): 3265 (m), 2927 (s), 2857 (s), 1630 (m), 1599
(m), 1534 (m), 1460 (s), 1378 (m), 1308 (m), 1243 (m), 1169 (w),
1070 (w), 1004 (m), 822 (m), 731 (m), 692 (m). HRMS: calcd m/z
384.0153 for C19H16BrNOP [M + H]+, measd 384.0144.
OC(PPh2){N(H)C6H4OMe-4} (6k). Method B. Recrystallized from
AUTHOR INFORMATION
Corresponding Author
*E-mail: Joseph.Schmidt@utoledo.edu. Tel: 419-530-1512.
Fax: 419-530-4033.
Notes
1
■
a CH2Cl2/pentane mixture. White solid (208 mg, 62%). H NMR
3
(C6D6, 23 °C): δ 7.61−7.58 (m, 4H, Ph-P), 7.28 (d, JH−H = 9.0 Hz,
2H, o-H), 7.11 (s, 1H, N-H), 7.05−7.04 (m, 6H, Ph-P), 6.61 (d, 3JH−H
= 9.0 Hz, 2H, m-H), 3.20 (s, 3H, OCH3). 13C{1H} NMR (C6D6, 23
1
2
°C): δ 174.47 (d, JP−C = 14.4 Hz), 156.85, 134.70 (d, JP−C = 19.6
1
3
Hz), 134.52, 134.27 (d, JP−C = 17.7 Hz), 129.76, 129.09 (d, JP−C
=
The authors declare no competing financial interest.
7.4 Hz), 121.01, 114.25, 54.82. 31P{1H} NMR (C6D6, 23 °C): δ 0.18.
IR (Nujol, cm−1): 3257 (m), 2927 (s), 2831 (s), 1690 (s), 1607 (s),
1590 (s), 1507 (s), 1497 (s), 1377 (s), 1299 (s), 1251 (s), 1164 (s),
1104 (m), 1025 (s), 891 (w), 821 (s), 752 (m), 730 (m), 691 (m),
636 (m). HRMS: calcd m/z 336.1153 for C20H19NO2P [M + H]+,
measd 336.1149.
ACKNOWLEDGMENTS
■
Acknowledgment is made to the Donors of the American
Chemical Society Petroleum Research Fund for support of this
research. We also gratefully acknowledge Dr. John F. Beck for
the synthesis of diphenylphosphine and for solving the X-ray
structure of compound 4 and Dr. Allen Oliver (University of
Notre Dame) and the staff of the Ohio Crystallography
Consortium housed at The University of Toledo for assistance
with X-ray crystallography.
OC(PPh2){N(H)C6H4CF3-4} (6l). Method B. White solid (329 mg,
1
88%). H NMR (C6D6, 23 °C): δ 7.55−7.52 (m, 4H, Ph-P), 7.16 (d,
3JH−H = 8.5 Hz, 2H, o-H), 7.07 (d, 3JH−H = 8.5 Hz, 2H, m-H), 7.06 (s,
1H, N-H), 7.06−7.04 (m, 6H, Ph-P). 13C{1H} NMR (C6D6, 23 °C): δ
1
3
175.92 (d, JP−C = 17.5 Hz), 140.95 (d, JP−C = 3.6 Hz), 134.68 (d,
2JP−C = 19.1 Hz), 133.60 (d, 1JP−C = 10.5 Hz), 130.08, 129.21 (d, 3JP−C
3
2
= 7.5 Hz), 126.32 (q, JF−C = 4.0 Hz), 126.08 (q, JF−C = 32.8 Hz),
124.76 (q, 1JF−C = 272.0 Hz), 119.09. 31P{1H} NMR (C6D6, 23 °C): δ
1.63. IR (Nujol, cm−1): 3220 (m), 2916 (s), 2838 (s), 1950 (w), 1898
(w), 1629 (s), 1525 (s), 1460 (s), 1403 (m), 1377 (m), 1316 (m),
1273 (m), 1208 (m), 930 (s), 856 (m), 761 (m), 708 (m), 665 (m),
635 (m), 600 (m). HRMS: calcd m/z 374.0922 for C20H16F3NOP [M
+ H]+, measd 374.0920.
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(262 mg, 65%).1H NMR (C6D6, 23 °C): δ 7.53 (t, 3JH−H = 3JP−H = 8.0
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dx.doi.org/10.1021/om300807k | Organometallics XXXX, XXX, XXX−XXX