Diligating tripodal amido-phosphine ligands: The effect of a proximal antipodal early transition metal on phosphine donor ability in a building block for heterometallic complexes

Article abstract of DOI:10.1021/ic060692d

The ligand precursors P(CH₂NH-3,5-(CF₃) ₂C₆H₃)₃ (1a), P(CH ₂NHPh)₃ (1b), and P(CH₂NH-3,5-Me ₂C₆H₃)₃ (1c), react with the reagents Ti(NMe₂)₄ and ^tBuN=Ta(NEt ₂)₃ to generate metal complexes of the type P(CH ₂NAr^R)₃TiNMe₂ (2a-c) and P(CH ₂NAr^R)₃Ta=N^tBu (3a-c) (where Ar ^R = 3,5-(CF₃)₂C₆H₃, Ph, and 3,5-Me₂C₆H₃). Due to ring strain, the phosphine lone pair cannot chelate and is available to bind a second metal, and this feature can be utilized to synthesize heterometallic polynuclear complexes. The ³¹P chemical shifts observed upon complexation of the early transition metals to the amido donors are large and in the opposite direction expected for the increased C-P-C bond angles in these complexes; these unusual shifts are due to P-Ti and P-Ta distances that are significantly shorter than the sum of van der Waals radii. The reaction of 2c with Ni(CO)₄ produces at first the bimetallic complex (CO)₃Ni[P(CH ₂N-3,5-Me₂C₆H₃) ₃TiNMe₂] (4c), which gradually converts to the trimetallic complex (CO)₂Ni[P(CH₂N-3,5-Me₂C ₆H₃)₃TiNMe₂]₂ (5c). The effect of the complexation of Ti and Ta fragments on the donor ability of the phosphine ligand was determined by the preparation of the bis-phosphine complexes trans-L₂Rh-(CO)Cl, (where L = 1a-c, 2a-c, and 3a-c) prepared by the reaction of the appropriate phosphine with [Rh(CO) ₂-(μ-Cl)]₂, and a measurement of the resultant CO stretching frequencies. Surprisingly, the complexes with the larger C-P-C angles are significantly poorer donors. Density functional theory calculations were performed to determine what factors affect the donor ability of the phosphine and if through-space interactions might play an important role in the observed electronic properties.

Full text of DOI:10.1021/ic060692d

Inorg. Chem. 2006, 45, 7435−7445
Diligating Tripodal Amido-Phosphine Ligands: the Effect of a Proximal
Antipodal Early Transition Metal on Phosphine Donor Ability in a
Building Block for Heterometallic Complexes
Hua Han, Mona Elsmaili, and Samuel A. Johnson*
Department of Chemistry and Biochemistry, UniVersity of Windsor, Windsor,
Ontario, Canada, N9B 3P4
Received April 24, 2006
The ligand precursors P(CH2NH-3,5-(CF3)2C6H3)3 (1a), P(CH2NHPh)3 (1b), and P(CH2NH-3,5-Me2C6H3)3 (1c), react
t
with the reagents Ti(NMe2)4 and BuN
d
Ta(NEt2)3 to generate metal complexes of the type P(CH2NArR)3TiNMe2
(2a− d − ) 3,5-(CF3)2C6H3, Ph, and 3,5-Me2C6H3). Due to ring strain,
c) and P(CH2NArR)3Ta NtBu (3a c) (where ArR
the phosphine lone pair cannot chelate and is available to bind a second metal, and this feature can be utilized
to synthesize heterometallic polynuclear complexes. The 31P chemical shifts observed upon complexation of the
early transition metals to the amido donors are large and in the opposite direction expected for the increased
C−P−C bond angles in these complexes; these unusual shifts are due to P−Ti and P−Ta distances that are
significantly shorter than the sum of van der Waals radii. The reaction of 2c with Ni(CO)4 produces at first the
bimetallic complex (CO)3Ni[P(CH2N-3,5-Me2C6H3)3TiNMe2] (4c), which gradually converts to the trimetallic complex
(CO)2Ni[P(CH2N-3,5-Me2C6H3)3TiNMe2]2 (5c). The effect of the complexation of Ti and Ta fragments on the donor
ability of the phosphine ligand was determined by the preparation of the bis-phosphine complexes trans-L2Rh-
(CO)Cl, (where L
-Cl)]2, and a measurement of the resultant CO stretching frequencies. Surprisingly, the complexes with the larger
C angles are significantly poorer donors. Density functional theory calculations were performed to determine
) 1a−c, 2a−c, and 3a−c) prepared by the reaction of the appropriate phosphine with [Rh(CO)2-
(
µ
C−P−
what factors affect the donor ability of the phosphine and if through-space interactions might play an important role
in the observed electronic properties.
Introduction
inert substrates.4 More recently, rational cluster synthesis has
been used for the tuning of physical properties, such as
single-molecule magnetism,5 and early-late heterobimetallics
have been used to synthesize unusual molecular architectures
via self-assembly.6
We have recently shown that ligands of the type P(CH2-
NArR)3, where ArR is an aryl substituent, can adopt a
conformation where the phosphine and amido lone pairs are
The chemistry of polynuclear and heterobimetallic1 clusters
has been of interest to chemists2 due to the ability of adjacent
metals to cooperatively activate substrates. This is observed
frequently in biological systems, where clusters of metals
can assist in the transfer of electrons3 to activate relatively
* To whom correspondence should be addressed. E-mail: sjohnson@
uwindsor.ca. Fax: (519) 973-7098.
(1) Stephan, D. W. Coord. Chem. ReV. 1989, 95, 41-107. Wheatley, N.;
(3) Gray, H. B.; Malmstroem, B. G. Biochemistry 1989, 28, 7499-7505.
(4) Messerschmidt, A.; Huber, R.; Wieghardt, K.; Poulos, T. Handbook
of Metalloproteins, Volume 1; Wiley: New York, 2001.
(5) Christou, G.; Gatteschi, D.; Hendrickson, D. N.; Sessoli, R. MRS Bull.
2000, 25, 66-71. Gatteschi, D.; Sessoli, R. Angew. Chem., Int. Ed.
2003, 42, 268-297.
(6) Alvarez-Vergara, M. C.; Casado, M. A.; Martin, M. L.; Lahoz, F. J.;
Oro, L. A.; Perez-Torrente, J. J. Organometallics 2005, 24, 5929-
5936. Stang, P. J.; Persky, N. E. Chem. Commun. 1997, 77-78.
Mokuolu, Q. F.; Avent, A. G.; Hitchcock, P. B.; Love, J. B. J. Chem.
Soc., Dalton Trans. 2001, 2551-2553. Mokuolu, Q. F.; Duckmanton,
P. A.; Hitchcock, P. B.; Wilson, C.; Blake, A. J.; Shukla, L.; Love, J.
B. Dalton Trans. 2004, 1960-1970.
Kalck, P. Chem. ReV. 1999, 99, 3379-3419.
(2) Braunstein, P.; Morise, X.; Benard, M.; Rohmer, M.-M.; Welter, R.
Chem. Commun. 2003, 610-611. Hernandez-Gruel, M. A. F.; Perez-
Torrente, J. J.; Ciriano, M. A.; Rivas, A. B.; Lahoz, F. J.; Dobrinovitch,
I. T.; Oro, L. A. Organometallics 2003, 22, 1237-1249. Kabashima,
S.-i.; Kuwata, S.; Hidai, M. J. Am. Chem. Soc. 1999, 121, 7837-
7845. Graham, T. W.; Llamazares, A.; McDonald, R.; Cowie, M.
Organometallics 1999, 18, 3502-3510. Spannenberg, A.; Oberthur,
M.; Noss, H.; Tillack, A.; Arndt, P.; Kempe, R. Angew. Chem., Int.
Ed. 1998, 37, 2079-2082. Gade, L. H.; Schubart, M.; Findeis, B.;
Fabre, S.; Bezougli, I.; Lutz, M.; Scowen, I. J.; McPartlin, M. Inorg.
Chem. 1999, 38, 5282-5294.
10.1021/ic060692d CCC: $33.50
Published on Web 08/03/2006
© 2006 American Chemical Society
Inorganic Chemistry, Vol. 45, No. 18, 2006 7435

Han et al.
Figure 1. Potential binding mode of the of P(CH2NArR)3 ligands to an
early transition metal fragment (shown as M) and a second metal complex
(shown as M′) along with an illustration of the major and minor lobes of
the lone pair orbital on phosphorus.
arranged approximately parallel and are incapable of all
chelating to the same metal; such a bonding mode was
observed in a nonanuclear Cu(I) complex.7 When M is a
high-oxidation-state early transition metal, the bonding mode
shown in Figure 1 is more likely, where the amido donors
chelate to the early transition metal.8 In this bonding mode,
the phosphine ligand cannot bind its lone pair to the metal
chelated by the amido donors but is well situated to bind to
a second metal complex, labeled in Figure 1 as M′.
Figure 2. ORTEP depiction of the solid-state structure of 1a as determined
by X-ray crystallography. Selected bond angles: C(1)-P(1)-C(2), 99.48-
(11); C(1)-P(1)-C(3), 99.38(15); C(2)-P(1)-C(3), 100.59(16); P(1)-
C(1)-N(1), 107.99(18); P(1)-C(2)-N(2), 107.79(16); C(1)-N(1)-C(4),
123.7(2); C(2)-N(2)-C(12), 120.95(19).
These ligands are thus well-suited for the facile synthesis
of early-late transition metal heterobimetallic complexes,
providing that some interaction between the two metal
centers bound to either side of the ligand is possible. A direct
through-space interaction between M and the minor lobe of
the lone-pair orbital could allow for communciation between
metal centers.9 Such an interaction could mitigate the transfer
of electrons between metals in complexes of these types or
facilitate magnetic coupling between the metals in paramag-
netic complexes. This paper describes an initial study on the
ability of this ligand to cooordinate both early and late
transition metals to prepare heterobimetallic and polynuclear
complexes and an investigation of the role of the nature of
the amido-chelated early transition metal on the properties
of the phosphine donor.
well using 3,5-dimethylaniline to produce 1c; however, using
3,5-bis(trifluoromethyl)aniline no reaction was observed with
the solvent-free methodology, and it was necessary use the
original procedure using toluene as the solvent and a Dean-
Stark apparatus to remove water to obtain 1a. For simplicity,
these ligand precursors will be abbreviated herein as [P(CH2-
NArR)]H3, where ArR ) 3,5-(CF3)2C6H3, Ph, and 3,5-
Me2C6H3, for a, b, and c, respectively. Ligand precursors
1a-c oxidize only slowly in air and are not particularly
moisture sensitive, although they were stored under a dry
nitrogen atmosphere.
Scheme 1
Results and Discussion
Ligand Precursor Syntheses. The ligand precursors
P(CH2NH-3,5-(CF3)2C6H3)3 (1a), P(CH2NHPh)3 (1b), and
P(CH2NH-3,5-Me2C6H3) (1c) were prepared using P(CH2-
OH)3 with the appropriate aniline, as shown in Scheme 1.
Although this reaction can be performed in toluene, with
water removed by azeotropic distillation using a Dean-Stark
apparatus, as previously reported for 1b,10 this requires the
use of an excess (5 equiv) of aniline. We found it more
convenient to perform the reaction neat and use dynamic
vacuum to remove the byproduct, water. This procedure
worked well with a stoichiometric amount of aniline, which
simplified the purification procedure. The reaction occurred
over 30 min and was exothermic. The product is analytically
pure when prepared in this manner, though it is easily
crystallized from a saturated warm toluene solution by
cooling to -40 °C. A solvent-free procedure also worked
Compounds 1b and 1c both crystallized as thin plates
unsuitable for crystallographic studies; however, crystals of
1a suitable for X-ray diffraction were obtained by slow
evaporation of a toluene solution. An ORTEP depiction of
the solid-state structure obtained at 133 K is shown in Figure
2. Unfortunately, this structure suffers slightly from disorder
of one of the ligand arms and rotational disorder of a majority
of the CF3 substituents. The C(1)-P(1)-C(2), C(1)-P(1)-
C(3), and C(2)-P(1)-C(3) angles for the free ligand
precursor 1c are 99.48(11)°, 99.38(15)°, and 100.59(16)°,
respectively, for a sum of 299.5(2)°; this value is fairly
typical for phosphine donors, whose C-P-C angles are
invariably much less than the tetrahedral angle of 109.5°.
This change in sum of C-P-C angles will be used to
evaluate the effects of complexation of early transition metals
to the amido donors on the phosphine donor (vide infra).
(7) Keen, A. L.; Doster, M.; Han, H.; Johnson, S. A. Chem. Commun.
2006, 1221-1223.
(8) Gade, L. H. Acc. Chem. Res. 2002, 35, 575-582; Gade, L. H. J.
Organomet. Chem. 2002, 661, 85-94. Jia, L.; Ding, E.; Rheingold,
A. L.; Rhatigan, B. Organometallics 2000, 19, 963-965.
(9) Hoffmann, R. Acc. Chem. Res. 1971, 4, 1-9.
(10) Frank, A. W.; Drake, G. L., Jr. J. Org. Chem. 1972, 37, 2752-2755.
7436 Inorganic Chemistry, Vol. 45, No. 18, 2006

Diligating Tripodal Amido-Phosphine Ligands
than the longest reported phosphine-titanium bond length
of 2.813 Å,12 although Ti-P bond distances are more
typically 2.6-2.7 Å.
Despite the fact that the phosphine lone pair is not
coordinated to the early transition metal center, the 31P{1H}
NMR shifts are strongly affected by the coordination of a
transition metal to the amido donors. A small range of
chemical shifts are observed for the free ligands by 31P{1H}
NMR spectroscopy: δ -32.6, -31.0, and -29.6 for 1a-c,
respectively. In 2a-c, both the shifts and the range covered
are vastly different, with shifts of δ -79.9, -65.6, and -61.6
for 2a-c, respectively. The change of the chemical shift to
higher field for 2a-c compared to their ligand precursors
was unexpected; an increase in C-P-C angle usually leads
to a significant shift to lower field. For example, the opposite
trend of chemical shifts vs C-P-C angle is observed for
the alkyl phosphines PMe3, PEt3, and PtBu3, whose 31P shifts
are δ -62, -20, and +63, respectively. The modeling of
31P NMR shifts is complex;13 however, these results indicate
that the phosphorus donor may be directly affected by its
proximity to the chelated early transition metal.
Figure 3. Solid-state molecular structure of 2b as determined by X-ray
crystallography. Hydrogen atoms are omitted for clarity. Selected distances
(Å): Ti(1)‚‚‚P(1), 2.9895(4); Ti(1)-N(1), 1.9239(11); Ti(1)-N(2), 1.9327-
(11); Ti(1)-N(3), 1.9424(11); Ti(1)-N(4), 1.8643(12). Selected bond
angles: C(1)-P(1)-C(2), 105.85(6); C(1)-P(1)-C(3), 102.64(6); C(2)-
P(1)-C(3), 102.89(6); Ti(1)-N(4)-C(22), 130.95(11); Ti(1)-N(4)-C(23),
115.22(10); Ti(1)-N(1)-C(1), 109.48(8); Ti(1)-N(1)-C(4), 132.54(9); Ti-
(1)-N(2)-C(2), 108.78(8); Ti(1)-N(2)-C(10), 133.75(9); Ti(1)-N(3)-
C(3), 109.80(8); Ti(1)-N(3)-C(16), 134.33(9); P(1)-C(1)-N(1), 116.64-
(9); P(1)-C(2)-N(2), 118.59(9); P(1)-C(3)-N(3); 117.06(9); C(1)-N(1)-
C(4), 117.13(11); C(2)-N(2)-C(10), 117.47(11); C(3)-N(3)-C(16),
115.74(10).
Titanium Complex Syntheses. The reactions of 1a-c
with Ti(NMe2)4 in toluene produce P(CH2NArR)3TiNMe2,
2a-c, as shown in eq 1. These reactions are slow at room
temperature and require 12-24 h to go to completion. No
intermediates were observed by 1H or 31P{1H} NMR
spectroscopy. The resultant products are all obtained in high
yields as thermally stable dark-red crystalline solids.
Tantalum Complex Syntheses. The reaction of 1a-c
with Ta(NEt2)3(NtBu) cleanly produced the tantalum imido
complexes P(CH2NArR)3TadNtBu, 3a-c, as shown in eq
2. The products were obtained in high yields as yellow
1
crystalline solids. As with 2a-c, the H NMR spectra of
3a-c are consistent with apparent C3V symmetry.
The solid-state structures of 2a-c were determined by
X-ray crystallography. An ORTEP depiction of the solid-
state molecular structure of 2b is shown in Figure 3; a
comparison of the bond lengths and angles with those of 2a
and 2c revealed little variation, although the quality of the
structure of 2c was hampered by the tendency of this com-
pound to crystallize as nonmerohedral twins. The structural
data for 2a and 2c are contained in the Supporting Informa-
tion. As anticipated, in all three structures, the tripodal ligand
chelates via three amido donors and the lone-pair of the
phosphine donor is directed away from the metal center.
A comparison of the C-P-C angles before and after the
introduction of a transition metal to the triamido chelate
provides some measure of the hybridization change at the
phosphine donor, which should affect its donor properties.
In 2b, the sum of C-P-C angles is 311.4(1)° compared to
299.5(2)° in 1a, which is a significant change. Although the
phosphine donor is hybridized so that the lone pair is
formally directed away from the early transition metal, the
binding of the ligand enforces P‚‚‚Ti distances that are under
the sum of van der Waals radii of these elements.11 For 2b,
the P‚‚‚Ti distance of 2.9895(4) Å for 2b is only ∼6% larger
The solid-state structure of 3b was determined by X-ray
crystallography, and an ORTEP depiction of the solid-state
molecular structure of 3b is shown in Figure 4. As with
complexes 2a-c, the triamido donors chelate to the early
transition metal, and the phosphine lone pair is directed away
from the Ta center. The C-P-C angles for 3b are larger
than those of the titanium complexes 2a-c, with a sum of
C-P-C angles of 315.0(2)°. Clearly, the chelation of a metal
requires an increase in the bond angles at P, with the greater
increase for the larger metal, Ta. This difference is more
than expected, considering the relatively small difference
between the size of Ti and Ta. Despite the slightly larger
size of Ta, the P‚‚‚Ta distance in 3b is 2.9548(6) Å, which
is shorter than the P‚‚‚Ti distance in 2b, and only 3.5% longer
than the longest reported phosphine-tantalum bond length
of 2.855 Å.14
The change in 31P NMR shifts of 1a-c upon coordination
of the amido donors to tantalum are more dramatic than those
(12) Shao, M.-Y.; Gau, H.-M. Organometallics 1998, 17, 4822-4827.
(13) Feindel, K. W.; Wasylishen, R. E. Can. J. Chem. 2004, 82, 27-44.
(14) van Doorn, J. A.; van der Heijden, H.; Orpen, A. G. Organometallics
1994, 13, 4271-4277.
(11) Bondi, A. J. Phys. Chem. 1964, 68, 441-451.
Inorganic Chemistry, Vol. 45, No. 18, 2006 7437

Han et al.
slightly larger donors, although realistically the aryl groups
can probably rotate so that cone angles predicted from the
location of these substituents overestimate the size of these
donors. Regardless, these complexes display remarkably
small cone angles, which are comparable to those of the
smallest of phosphine donors. For comparison, the cone
angles of PMe3, PEt3, PPh3, and P(OEt)3 are all larger, at
118°, 132°, 145°, and 109°, respectively.
The electronic properties of many phosphines have been
characterized by measurement of the A1 stretching frequency
of complexes prepared by replacement of a CO group in
Ni(CO)4 by a single phosphine donor. Less-toxic compounds
than Ni(CO)4 are now more commonly used to characterize
the electronic properties of phosphines; however, we opted
to prepare a complex of Ni(CO)4 to have a chance to compare
the parameters of some of these phosphine complexes
directly with large database of data available for adducts of
the Ni(CO)3 moiety. Compound 2c reacted instantaneously
with excess Ni(CO)4 to afford, at first, a single product,
which was determined to be (CO)3Ni[P(CH2NArMe)3]-
Figure 4. Solid-state molecular structure of 3b as determined by X-ray
crystallography. Hydrogen atoms are omitted for clarity. Selected distances
(Å): Ta(1)‚‚‚P(1), 2.9548(6); Ta(1)-N(1), 2.004(2); Ta(1)-N(2), 1.998-
(2); Ta(1)-N(3), 1.990(2); Ta(1)-N(4), 1.7682(18). Selected bond angles
in degrees: C(1)-P(1)-C(2), 103.91(13); C(1)-P(1)-C(3), 105.77(12);
C(2)-P(1)-C(3), 105.27(12); Ta(1)-N(1)-C(1), 105.77(15); Ta(1)-N(1)-
C(4), 137.42(15); C(1)-N(1)-C(4), 116.8(2); Ta(1)-N(2)-C(2), 105.27-
(15); Ta(1)-N(2)-C(10), 138.42(16); C(2)-N(2)-C(10), 116.3(2); Ta(1)-
N(3)-C(16), 135.96(17).
observed for titanium, though the range of observed shifts
is smaller, with shifts of δ -108.5, -100.9, and -100.1 for
complexes 3a-c, respectively. Contrary to what might be
expected, the trend of phosphorus shifts for the free ligand,
Ti, and Ta complexes seem to indicate that the phosphine
donors are becoming poorer donors with increasing C-P-C
angle; however, it is difficult to be certain that the changes
in chemical shift truly represent a reduced donor ability of
the phosphine donor.
Characterization of the Phosphine Donor. The standard
measures of a phosphine donor are its electronic parameter,
usually obtained from the symmetric CO stretching frequency
of a carbonyl complex of the phosphine,15 and the cone angle,
as defined by Tolman with respect to Ni(CO)3 complexes.16
Although numerous other approaches have been described,
most still attempt to classify the properties of a phosphine
in terms of steric17-19 and electronic effects.20 From the
structure of the titanium complex 2b, the cone angle of the
phosphine donor can be estimated as 100° if the methylene
hydrogens are used to define the cone angle, where the
hydrogen atom is given a radius of 0.6 Å, and a metal-P
distance of 2.28 Å is assumed, as described by Tolman. For
the tantalum complex 3b, the estimated cone angle is 103°,
which is larger due to the increase in C-P-C angles relative
to the titanium complexes. For 2a and 2c, the trifluoromethyl
or methyl meta substituents define the cone angle, rather than
the methylene hydrogens, which makes these complexes
1
TiNMe2, 4, as assessed by H, 13C{1H}, and 31P{1H} NMR
spectroscopy. The coordination of phosphorus to nickel is
accompanied by a large 31P{1H} NMR shift from δ -61.6
in 2c to δ +4.1,21 and the 13C{1H} carbonyl carbon resonance
2
at δ 196.3, which is a doublet with a typical JPC value of
1.1 Hz,22 confirms the coordination of a single phosphine
donor. The symmetric A1 carbonyl stretching frequency of
a 0.05 mol L-1 solution of (CO)3Ni[P{CH2N(C6H3R2)}3-
TiNMe2] in CH2Cl2 was 2073.7 cm-1; this can be compared
to the extensive data tabulated by Tolman.16 Compared to
other phosphine ligands, P(CH2NArR)3]TiNMe2 is signifi-
cantly less strongly electron-donating than the common alkyl
phosphines PMe3 (υCO(A1) ) 2064.1 cm-1), and slightly less
electron donating than the ubiquitous PPh3 (υCO(A1) ) 2068.9
cm-1). The electronic parameter for 4 is almost identical to
PHPh2 (υCO(A1) ) 2073.3 cm-1). As a phosphine ligand,
complex 4 appears to be a capable π-acceptor but not as
strong a π-acid as typical phosphites, such as P(OEt)3 (υCO
-
(A1) ) 2076.3 cm-1).
Compound 4 is not stable at room temperature, and
solutions undergo ligand redistribution over the course of
48 h to form over 50% (CO)2Ni[P(CH2NArMe)3TiNMe2]2,
5, presumably with loss of Ni(CO)4. This reaction sequence
is depicted in Scheme 2. The 31P{1H} NMR spectrum shows
an additional peak at δ 7.0, and the 13C{1H} NMR carbonyl
resonance is a triplet at δ 190.0 due to coupling to two
identical phosphorus nuclei. The resonance for the methylene
carbon, which is typically a doublet due to a 1JPC of around
15 Hz, in this case is a virtual triplet due to the AA′XX′
spin system. Further ligand redistribution appears to occur
as the conversion to 5 increases and results in the formation
of an impurity, which is presumably the trisubstituted
complex; this makes the high-yield isolation of pure 5 by
this procedure difficult. Addition of an equivalent of 2b to
(15) Strohmeier, W.; Mueller, F. J. Chem. Ber. 1967, 100, 2812-2821.
Tolman, C. A. J. Am. Chem. Soc. 1970, 92, 2953-2956.
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ReV. 2002, 233-234, 41-51. Ferguson, G.; Roberts, P. J.; Alyea, E.
C.; Khan, M. Inorg. Chem. 1978, 17, 2965-2967.
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Pittard Karl, A.; Temple, M. D.; Zhao, Y. J. Am. Chem. Soc. 2003,
125, 4318-4324.
(19) Dunne, B. J.; Morris, R. B.; Orpen, A. G. J. Chem. Soc., Dalton Trans.
1991, 653-661.
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Organometallics 1989, 8, 1-7. Bush, R. C.; Angelici, R. J. Inorg.
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7438 Inorganic Chemistry, Vol. 45, No. 18, 2006

Diligating Tripodal Amido-Phosphine Ligands
Scheme 2
Figure 5. ORTEP depiction of the solid-state molecular structure of
(CO)2Ni[P(CH2N-3,5-Me2C6H3)3TiNMe2]2 (5). Hydrogen atoms are omitted
for clarity. Selected distances (Å): P(1)-Ni(1), 2.1835(13); P(2)-Ni(1),
2.1900(14); Ti(1)‚‚‚P(1), 3.087(5); Ti(2)‚‚‚P(2), 3.097(5); N(1)-Ti(1),
1.938(4); N(2)-Ti(1), 1.942(4); N(3)-Ti(1), 1.922(4); N(4)-Ti(1), 1.872-
(4); N(5)-Ti(2), 1.943(4); N(6)-Ti(2), 1.937(4); N(7)-Ti(2), 1.923(4);
N(8)-Ti(2), 1.857(4). Selected angles in degrees: P(1)-Ni(1)-P(2),
104.00(5); C(59)-Ni(1)-C(60), 111.4(2); P(1)-Ni(1)-C(59), 111.22(19);
P(1)-N(1)-C(60), 109.96(17); P(2)-Ni(1)-C(59), 110.98(16); P(2)-Ni-
(1)-C(60) 108.97(19); C(1)-P(1)-C(2), 102.4(2); C(2)-P(1)-C(3), 103.7-
(2); C(3)-P(1)-C(1), 101.4(2); C(30)-P(2)-C(31), 101.3(2); C(31)-
P(2)-C(32), 103.6(2); C(30)-P(2)-C(32), 101.5(2); C(1)-P(1)-Ni(1),
116.31(14); C(2)-P(1)-Ni(1), 116.34(15); C(3)-P(1)-Ni(1), 114.66(15);
C(30)-P(2)-Ni(1), 114.98(14); C(31)-P(2)-Ni(1), 117.10(16); C(32)-
P(2)-Ni(1), 116.09(15).
a freshly prepared sample of 4 proved to be the most effective
synthesis of 5.
The molecular structure of 5 was determined by single-
crystal X-ray crystallography and is shown in Figure 5. The
bonding of the phosphine donor to nickel appears to have
some effects on the structure of the ligand. The Ti(1)‚‚‚P(1)
and Ti(2)‚‚‚P(2) short contacts are 3.087(5) and 3.097(5) Å,
respectively, whereas in 2c, a Ti‚‚‚P distance of 3.015(5) Å
was observed, a difference of 0.08(1) Å. The sum of C-P-C
angles for P(1) and P(2) are 307.5(3)° and 306.4(3)°,
respectively, which is a slight decrease from 310.5(5)° in
2c. This result is quite unusual because the coordination of
phosphine donors to metal centers almost invariably results
in an increase of C-P-C angles by 3° or 4°, even in related
cyclic systems such as P(CH2O)3P; this effect is often
explained by the simple application of VSEPR theory.
Although the absence of an increase in C-P-C angles could
be explained by the initial strain on the ligand to accom-
modate the large Ti metal center, the decrease in C-P-C
angle upon coordination to Ni is not easy to rationalize. This
compression of C-P-C angles has a considerable effect on
the geometry at Ti. The sum of the N(1)-Ti(1)-N(2), N(2)-
Ti(1)-N(3), and N(1)-Ti(1)-N(3) angles decreases from
316.4(1)° in 2b to 304.0(3)° in 5, both of which deviate
considerably from the 328.5° expected for a tetrahedral
structure.
Another method to assess the steric bulk of a phosphine
is the symmetric deformation coordinate, which is defined
as the difference between the sum of these C-P-C and Ni-
P-C angles.19 In 5, the sum of Ni(1)-P-C angles for P(1)
and P(2) is 347.3(3)° and 348.2(3)°, respectively, which
results in symmetric deformation coordinates of 39.8(4)° and
41.8(4)° for P(1) and P(2), respectively. As with the cone
angle, these values are indicative of a small donor.
Examination of the geometry at Ni(1) in the structure of
5 reveals a few points worthy of mention. The P(1)-Ni(1)
and P(2)-Ni(1) distances are 2.1835(13) and 2.1900(14) Å,
respectively, which is approximately 0.1 Å shorter than the
average phosphine-nickel bond length of 2.28 Å. A direct
measurement of the cone angle of these ligands yields a value
of 106°, a value larger than we estimated from the structure
of 2b; however, this increase is entirely due to the shorter
than average Ni-P bond length. The diminutive nature of
these phosphines is apparent from the P(1)-Ni(1)-P(2)
angle of 104.00(5)°, which is significantly smaller than the
tetrahedral angle of 109.5°.
Phosphine Electronic Parameters from Reactions with
[Rh(CO)2(µ-Cl)]2. The addition of 4 equiv of most phos-
phine donors to [Rh(CO)2(µ-Cl)]2 allows for the facile
preparation of trans-rhodiumcarbonylchlorobisphosphine com-
plexes, and the CO stretching frequency of these adducts
have been used extensively in the past to determine electronic
parameters for phosphine ligands. To avoid the repeated
handling of highly toxic Ni(CO)4, we chose to evaluate the
electronic properties of the phosphine donor in 1a-c, 2a-
c, and 3a-c by this method. 1H and 31P{1H} NMR
spectroscopy was used to identify the products as the trans-
rhodiumcarbonylchlorobisphosphine complexes 6a-c, 7a-
c, and 8a-c of the phosphines 1a-c, 2a-c, and 3a-c,
respectively, as shown in Scheme 3. The products were all
formed within 20 min of dissolving the reagents in CH2Cl2.
The adduct of 3c, trans-Cl(CO)Rh[P(CH2NArMe)3Tad
NtBu]2 (8c) was isolated and characterized by X-ray crystal-
lography. The solid-state molecular structure of 8c is shown
in Figure 6. The crystallographically imposed symmetry in
the structure of 8c is C3h, which leads to a 3-fold disorder
of the carbonyl and chloride ligands; only one location is
shown in Figure 6. In a projection along the P-Rh-P 3-fold
axis, the larger Cl ligand is staggered with respect to the
P-CH2 bonds, whereas the smaller carbonyl ligand is
eclipsed. The sum of C-P-C angles is 319.0(3)°, which is
approximately 4° larger than the sum of C-P-C angles in
3b; this increase in C-P-C angle is typical for the
coordination of phosphine to metal centers, unlike the
decrease of C-P-C angle noted previously for complex 5.
Inorganic Chemistry, Vol. 45, No. 18, 2006 7439

Han et al.
Scheme 3
Table 1. Crystallographic Data for Compounds 1a, 2b, 3b, 5, and 8c
1a
2b
3b
empirical formula
formula weight
C27H18F18N3P
757.41
C23H27N4PTi
438.33
C25H30N4PTa
598.45
crystal system
a, Å
b, Å
c, Å
orthorhombic
15.620(2)
16.410(2) Å
22.386(3)
90.0
monoclinic
11.9600(8)
14.4825(9)
12.8136(8)
90.0
90.081(1)
90.0
2219.45(2)
P21/n
monoclinic
27.980(3)
11.7166(12)
19.371(2)
90.0
131.3410(10)
90.0
4767.9(8)
C2/c
R, deg
â, deg
90.0
90.0
γ, deg
V, Å3
5738.0(13)
Pbca (No. 61)
8
space group
Z value
µ(Mo KR)
T
4
8
0.239 mm-1
133 K
0.474 mm-1
173 K
4.697 mm-1
173 K
total no. of reflns
no. of unique reflns
residuals: R1; wR2 (all data)
61 351
6569 (Rint ) 0.0282)
0.077; 0.187
17 442
3903 (Rint ) 0.019)
0.034; 0.090
26 207
5417 (Rint ) 0.021)
0.022; 0.046
5
C65H90N8NiO2P2Ti2
1231.90
8c
C63H84ClN8OP2RhTa2
1531.58
empirical formula
formula weight
crystal system
a, Å
b, Å
c, Å
triclinic
hexagonal
14.2228(8)
14.2228(8)
25.594(3)
90.0
15.417(3)
15.812(3)
16.336(3)
111.303(2)
109.839(2)
95.691(2)
3375.6(11)
P1h
R, deg
â, deg
90.0
120.0
γ, deg
V, Å3
4483.7(6)
P63/m (No. 176)
2
space group
Z value
µ(Mo KR)
T
2
0.601 mm-1
173 K
2.714 mm-1
173 K
total no. of reflns
no. of unique reflns
residuals: R1; wR2 (all data)
32 235
11 867 (Rint ) 0.069)
0.109; 0.174
49 687
3513 (Rint ) 0.0429)
0.056; 0.1254
As a result, the tantalum center moves further into the
chelating amides compared to the structure of 3b and the
P(1)‚‚‚Ta(1) distance of 2.943(2) Å is 0.012(2) Å shorter
than in 3b, as might be expected considering the larger
C-P-C angles. The P(1)‚‚‚Ta(1) distance in 8c is only 3.0%
longer than the longest crystallographically characterized
tantalum-phosphine bonding interaction.14 The sum of Rh-
P-C angles is 337.4(3)°, which leads to a symmetric
deformation coordinate of 18.4(4)°, which is less than half
the value observed in the titanium-nickel complex, 5.
The CO stretching frequencies of CH2Cl2 solutions of 6a-
c, 7a-c, and 8a-c are presented in Table 2 and plotted
versus the 31P chemical shifts of the precursors 1a-c, 2a-
c, and 3a-c in Figure 7. It is clear from this chart that the
effect of the different aryl substituents is very significant
even for the ligand precursor complexes 6a-c, despite the
distance of these substituents from the phosphine donor. Such
an influence demonstrates that the lone pairs on the nitrogen
atoms are important in determining the electronic properties
of these donors even in the absence of a transition metal.
There is evidence for a preferential orientation of the nitrogen
lone pairs with respect to both the aromatic ring substituents
and the phosphine donor in the structure of 1c, shown in
Figure 2; the two ligand arms associated with N(1) and N(2)
Figure 6. ORTEP depiction of the solid-state molecular structure of 8c
as determined by X-ray crystallography. Only one pair of the three
disordered sites of occupancy of the Cl and CO ligands is shown, and
hydrogen atoms are omitted for clarity. Selected distances (Å): P(1)‚‚‚Ta-
(1), 2.943(2); N(1)-Ta(1), 1.995(4); N(2)-Ta(1), 1.787(9); P(1)-Rh(1),
2.292(2). Selected bond angles: C(1)-P(1)-C(1), 106.33(19); Rh(1)-
P(1)-C(1), 112.46(17).
7440 Inorganic Chemistry, Vol. 45, No. 18, 2006

Diligating Tripodal Amido-Phosphine Ligands
1
Table 2. Metal Carbonyl Stretching Frequencies of Compounds 6a-c, 7a-c and 8a-c in CH2Cl2, Their JRhP Coupling Constants and 31P NMR
Shifts, and the 31P NMR Shifts of the Phosphine Donors 1a-c, 2a-c, and 3a-c
Rh(I)
complex
coordinated
31P shift
ligand
phosphine donors
ν
CO (cm-1
)
1JRh-P
31P shift
3
6a
6b
6c
7a
7b
7c
8a
8b
8c
P(CH2NHArCF
P(CH2NHPh)3
)
3
1984.9
1976.3
1973.2
1988.0
1979.5
1975.3
1990.5
1986.7
1986.6
120.1
118.1
116.9
130.3
125.8
122.5
143.6
138.1
136.9
+22.6
+23.7
+23.5
+3.8
+15.7
+18.5
-34.2
-32.8
-32.3
-32.6 (1a)
-31.0 (1b)
-29.6 (1c)
-79.9 (2a)
-65.6 (2b)
-61.6 (2c)
-108.5 (3a)
-100.9 (3b)
-100.1 (3c)
P(CH2NHArMe
)
3
P(CH2NArCF )3TiNMe2
P(CH2NPh)3TiNMe2
P(CH2NArMe)3TiNMe2
3
P(CH2NArCF )3TadNC(CH3)3
3
P(CH2NPh)3TadNC(CH3)3
P(CH2NArMe)3TadNC(CH3)3
to 120.1 Hz, with the largest values for 6a, which bears the
most electron-withdrawing substituents. An increase in
phosphine lone pair s-orbital character is consistent with the
poorer donor ability of this phosphine, although many factors
can affect Rh-P coupling constants.16 The same trend is
observed for complexes 7a-c, and the poorer donor abilities
of these phosphines relative to 6a-c are consistent with their
1
larger JRhP values, which range from 122.5 to 130.3 Hz.
For the tantalum complexes, there is a similar trend. For 8a-
c, the 1JRhP values range from 136.9 to 143.6 Hz, all of which
1
are greater than the JRhP values for 6a-c and 7a-c.
It is known that phosphines with larger cone angles have
smaller changes in 31P NMR shift upon coordination to
rhodium.23 The differences in 31P chemical shifts between
1a-c and their rhodium complexes 6a-c are δ 52.2, 54.7,
and 56.1, respectively, which are consistent with a cone angle
of approximately 110°. This trend of increasing shift with
increasing donor ability is reversed for the pair of 2a-c and
7a-c; these differences in shifts are δ 83.7, 81.3, and 80.1,
respectively. The significantly larger coordination shift
relative to 1a-c can be attributed to the smaller cone angle
for this phosphine donor. The differences in 31P chemical
shift for 3a-c and 8a-c are δ 74.3, 68.1, and 67.8,
respectively, which reflects the fact that phosphines 3a-c
have slightly larger cone angles than their Ti analogues but
still smaller than 1a-c.
Calculations. From the spectroscopic data, the role of the
chelated metals on the electronic properties of the phosphine
donors is clear but the mechanism by which the metal affects
the donor properties is not. A simple hypothesis would be
that the increase in C-P-C angle required to coordinate a
transition metal would render these stronger σ-donors, as the
lone pairs would possess less s-orbital character. Addition-
ally, the increased negative charge on the amido donors in
complexes 2a-c and 3a-c relative to 1a-c would be
expected to render the ligands containing a chelated early
transition metal more strongly electron donating. Only an
increase in the stability of the amido lone pair by π-back-
donation to the early transition metal center could conceiv-
ably render the phosphine a weaker donor relative to 1a-c.
There is a similarity of the complexes studied herein to
compounds such as diazabicyclo[2,2,2]octane (N(CH2-
CH2)3N), where it was noted that there is little through-space
overlap of the orbitals on nitrogen but enough through-bond
Figure 7. 31P NMR chemical shift vs carbonyl stretching frequencies for
complexes 6a-c, 7a-c, and 8a-c.
are aligned so that their aromatic substituents, C(1), C(2),
and P(1) are nearly coplanar. The effect of the aryl
substituents is also apparent in the CO stretching frequencies
of the titanium complexes, 7a-c. The effect of the aryl
substituents for these titanium complexes is practically
identical to that observed for 6a-c, although the titanium
complexes are nearly uniformly less strongly donating than
6a-c. In contrast, the CO stretches for the tantalum
complexes 8a-c are much less affected by the aryl substit-
uents. The range of CO stretching frequencies for 8a-c spans
only 3.8 cm-1 for the three different aryl substituents,
whereas for 6a-c and 7a-c, the ranges spanned are 11.7
and 12.7 cm-1, respectively. Complexes 8b and 8c have
nearly identical CO stretching frequencies. There is a near-
linear trend to decreasing 31P chemical shift with the
decreasing donor ability of the phosphine for each set of
complexes, 6a-c, 7a-c, and 8a-c. Between sets of
complexes, there is no linear trend between chemical shift
and donor ability; however, the highest-field 31P NMR
chemical shifts do correlate with the weaker σ-donating
phosphines. The most strongly donating phosphine ligands,
1b-c and 2b-c, have similar donor properties to PPh3,
which exhibits a CO stretching frequency of 1978 cm-1 in
the complex trans-Rh(CO)Cl(PPh3)2.
Table 2 also contains the 31P NMR shifts and 1JRhP values
for complexes 6a-c, 7a-c, and 8a-c, along with the 31P
NMR shifts of the phosphine donors 1a-c, 2a-c, and 3a-
c. For complexes 6a-c, the 1JRhP values ranges from 116.9
(23) Shaw, B. L.; Mann, B. E.; Masters, C. J. Chem. Soc. A 1971, 1104-
1106.
Inorganic Chemistry, Vol. 45, No. 18, 2006 7441

Han et al.
The minor lobe of this orbital clearly extends back close to
the tantalum center; however, there is no large contribution
from the metal center in this orbital; any stabilization of the
lone-pair orbital via direct through-space interaction must
be largely electrostatic. An electrostatic stabilization of the
phosphine lone pair would explain why the Ta(V) complexes
are poorer donors than the Ti(IV) complexes. The reason
for the lack of contribution from a tantalum-based orbital is
not the lack of an orbital of appropriate symmetry but rather
the energy difference between the metal-based orbital and
the lone pair. The appropriate orbital is the LUMO+2 and
is shown in Figure 8. This metal-based orbital extends
considerably toward the phosphorus nucleus, and it is
conceivable that by using a different transition metal frag-
ment in the amido chelate a through-space covalent interac-
tions between the transition metal and phosphine donor could
be observed.
Conclusions. Ligands of the type P(CH2NArR)3 readily
bind early transition metals using the amido donor, while
retaining a phosphorus donor to bind to late transition metals,
which allows for the facile syntheses of early-late hetero-
bimetallics. The 31P NMR shifts upon coordination of an
early transition metal to the amido donors are opposite to
the typical trend of increasing chemical shift with increasing
C-P-C angle, and interactions with the transition metal d
orbitals are likely the cause of these unusual 31P NMR
chemical shifts.
Figure 8. Depiction of the phosphorus lone pair orbital, HOMO-8, and
Ta dz orbital, LUMO+2 for complex 3b, as determined by DFT using the
B3LYP functional and LANL2DZ basis functions.
interactions to render the in-phase and out-of-phase combina-
tion of lone-pair orbitals on nitrogen different energies.24 It
is interesting to note that in the radical cation of diazabicyclo-
[2,2,2]octane, (N(CH2CH2)3N)•+, the ESR spectrum is in-
dicative of a symmetric species, with equal coupling to two
14N nuclei; however; it is unclear if this is delocalization is
due to spatial overlap of the nitrogen orbitals or to rapid
electron transfer through the ethylene bridge carbons.25 The
separation of the nitrogen atoms in diazabicyclo[2,2,2]octane
complexes is typically around 2.6 Å, which is only ∼0.4 Å
shorter than the Ti‚‚‚P and Ta‚‚‚P distances observed here,
and the significantly larger radii of both these transition
metals and the phosphorus nuclei compared to nitrogen could
allow for a direct through-space interaction.9 Such an
interaction could involve the overlap of a metal-based orbital
with the minor lobe of the orbital associated with the lone
pair. Alternatively, a net stabilization of the phosphine-based
lone pair could occur by simple electrostatic interaction,
providing a significant amount of electron density in the lone
pair orbital resided close to the positively charged early
transition metal center. With larger C-P-C angles increased
p-orbital contribution to the lone pair orbital is anticipated,
which should increase the relative magnitude of the minor
lobe in this orbital. There is precedent for interactions of
the minor lobe of a phosphine donor with a proximal
transition metal center in the lowering of the inversion barrier
for a phosphine.26
A DFT calculation was performed on complex 3b,
constrained to C3 symmetry, using the B3LYP functional
and the LANL2DZ basis function set provided in Gaussian
03. This level of theory overestimates the P‚‚‚Ta distance
by approximately 0.1 Å but otherwise adequately reproduces
the crystallographically observed bond lengths and angles.
A depiction of the HOMO-8, which is the orbital with the
largest contribution from the lone pair on phosphorus, is
shown in Figure 8. A natural bond order analysis determined
the phosphorus lone pair to be of 50.03% p-orbital and
49.97% s-orbital character, which is reasonably close to that
expected for the calculated C-P-C bond angle of 103°.27
These are atypical phosphine donors, by virtue of the
strained C-P-C angles required to chelate the early transi-
tion metals, as well as due to direct interactions between
the early transition metal and the phosphine donor. The donor
abilities of the titanium complexes are similar to those of
the ubiquitous triphenylphosphine, but these are an unusual
set of donors because their cone angles are similar to only
the smallest trialkyl phosphines.18,28
Experimental Section
General Procedures. Unless otherwise stated, all manipulations
were performed under an inert atmosphere of nitrogen using either
standard Schlenk techniques or an MBraun glovebox. Dry, oxygen-
free solvents were employed throughout. Anhydrous pentane,
toluene, diethyl ether, and THF were purchased from Aldrich,
sparged with dinitrogen, and passed through activated alumina under
a positive pressure of nitrogen gas; toluene and hexanes were further
deoxygenated using Ridox catalyst columns.29 Deuterated benzene
was dried by heating at reflux with sodium/potassium alloy in a
sealed vessel under partial pressure, then trap-to-trap distilled, and
freeze-pump-thaw degassed three times. Deuterated methylene
chloride was heated in a sealed vessel over CaH2, then trap-to-trap
distilled, and freeze-pump-thaw degassed three times. NMR
spectra were recorded on Bruker AMX (300 MHz) or Bruker AMX
(500 MHz) spectrometer. All chemical shifts are reported in ppm,
and all coupling constants are in Hz. For 19F{1H} NMR spectra,
trifluoroacetic acid was used as the external reference at 0.00 ppm.
1H NMR spectra were referenced to residual protons (C6D5H, δ
7.15; C7D7H, δ 2.09) with respect to tetramethylsilane at δ 0.00.
(24) Takahashi, M.; Matsuo, M.; Udagawa, Y. Chem. Phys. Lett. 1999,
308, 195-198. Nelsen, S. F.; Buschek, J. M. J. Am. Chem. Soc. 1974,
96, 7930-7933. Heilbronner, E.; Muszkat, K. A. J. Am. Chem. Soc.
1970, 92, 3818-3821.
(25) McKinney, T. M.; Geske, D. H. J. Am. Chem. Soc. 1965, 87, 3013-
3014.
(26) Fryzuk, M. D.; Giesbrecht, G. R.; Rettig, S. J. Inorg. Chem. 1998,
37, 6928-6934.
(27) Nixon, J. F.; Pidcock, A. Annu ReV. NMR Spectrosc. 1969, 2, 345-
422.
(28) Fey, N.; Tsipis, A. C.; Harris, S. E.; Harvey, J. N.; Orpen, A. G.;
Mansson, R. A. Chem. Eur. J. 2005, 12, 291-302.
(29) Pangborn, A. B.; Giardello, M. A.; Grubbs, R. H.; Rosen, R. K.;
Timmers, F. J. Organometallics 1996, 15, 1518-1520.
7442 Inorganic Chemistry, Vol. 45, No. 18, 2006

Diligating Tripodal Amido-Phosphine Ligands
31P{1H} NMR spectra were referenced to external 85% H3PO4 at
δ 0.0. 13C{1H} spectra were referenced relative to solvent reso-
nances (C6D6, δ 128.0; C7D8, δ 20.4). Elemental analyses were
performed by the Centre for Catalysis and Materials Research
(CCMR), Windsor, Ontario, Canada. The compounds tris(hydroxyl-
methyl)phosphine, aniline, 3,5-dimethylaniline, 3,5-bis(trifluoro-
methyl)aniline, Ni(CO)4, TiCl4, LiNMe2, Ta(NEt3)2(NtBu), and
[(CO)2Rh(µ-Cl)]2 were purchased from Aldrich and used as
received. The complex Ti(NMe2)4 was prepared from the reaction
of TiCl4 and LiNMe2 and distilled prior to use.30 Nickel tetracar-
bonyl, Ni(CO)4, is highly toxic and should be handled with care.
(d, JPC ) 13.1 Hz, PCH2), 112.2 and 120.9 (s, Ph o-C and m-C),
139.1 (s, Ph p-C), 149.3 (d, J ) 4.8 Hz, ipso-C). 31P{1H} NMR
(C6D6, 121.5 MHz, 298 K): δ -29.6 (s). Anal. Calcd for
C27H36N3P: fw 433.57; C, 74.80; H, 8.37; N, 9.69. Found: C,
74.50; H, 8.49 N, 9.40.
P(CH2NArCF )3TiNMe2 (2a). A solution of Ti(NMe2)4 (754.78
3
mg, 3.37 mmol) in toluene (60 mL) was added to a solution of 1a
(2.55 g, 3.37 mmol) in 50 mL of toluene. The pale yellow solution
was stirred for 10 h and turned dark red. The solvent was removed
under vacuum, and the remaining dark red solid was rinsed with a
small portion of pentane and then dried under vacuum (2.45 g,
85%). X-ray-quality crystals were obtained by slow evaporation
of a benzene solution. 1H NMR (C6D6, 300 MHz, 298 K): δ 2.85
(s, 6H, NCH3), 3.18 (d, 6H, 2JPH ) 7.0 Hz, PCH2), 6.81 (s, 6H, Ph
o-H), 7.40 (s, 3H, Ph p-H). 13C{1H} NMR (C6D6, 125.8 MHz, 298
K): δ 41.2 (s, TiNCH3), 44.1 (d, JPC ) 24.2 Hz, PCH2), 113.4
and 122.1 (s, Ph o-C and m-C), 116.0 (s, Ph p-C), 132.6 (q, J )
32.9 Hz, PhC-F3), 152.9(d, ipso-C). 31P{1H} NMR (C6D6, 121.5
MHz, 298 K): δ -79.9 (s). 19F{1H} NMR (C6D6, 282.1 MHz, 298
K): δ 14.88 (s). Anal. Calcd for C29H21F18N4PTi, fw 846.32. C,
41.16; H, 2.50; N, 6.62. Found: C, 40.72; H, 2.70; N, 6.71.
P[CH2NH-3,5-(CF3)2C6H3]3 (1a). A mixture of P(CH2OH)3 (5.0
g, 90%, 0.0362 mol), 3,5-bis(trifluoromethyl)aniline (28 mL, 41.5
g, 5 equiv), and toluene (60 mL) were mixed in a 250 mL three-
neck flask equipped with a Dean-Stark trap and a condenser. The
solution was heated to reflux for 30 min, and the water was collected
and removed from the trap. The solution was allowed to cool, and
then the remaining solvent was removed under vacuum. The
addition of pentane (80 mL) dissolved the excess 3,5-bis(trifluo-
romethyl)aniline and precipitated the product as a fine white solid,
which was collected by filtration and dried under vacuum. X-ray-
quality crystals were obtained from slow evaporation of the toluene
P(CH2NPh)3TiNMe2 (2b). Prepared in an analogous manner to
2a from Ti(NMe2)4 (2.63 g, 11.73 mmol) and 1b (4.09 g, 11.73
mmol) using a reaction time of 12 h. Yield 4.10 g (83%). 1H NMR
(C6D6, 500.1 MHz, 298 K): δ 2.98 (s, 6H, TiNMe2), 3.84 (d, 6H,
2JPH ) 6.7 Hz, PCH2), 6.72 (d, 6H, 3JHH ) 8.3 Hz, Ph o-H), 6.86
(t, 3H, Ph p-H), 7.20 (m, 6H, Ph m-H). 13C{1H} NMR (C6D6, 125.8
MHz, 298 K): δ 42.4 (s, TiNMe2), 45.9 (d, JPC ) 20.2 Hz, PCH2),
117.7 and 129.7 (s, Ph o-Cand m-C), 120.9 (s, Ph p-C), 154.2 (m,
ipso-C). 31P{1H} NMR (C6D6, 202.5 MHz, 298 K): δ -65.6 (s).
Anal. Calcd for C23H27N4PTi: fw 438.33. C, 63.02; H, 6.21; N,
12.78. Found: C, 63.24; H, 6.25 N, 12.44.
1
solution. Yield 20.2 g, 73%. H NMR (C6D6, 300 MHz, 298 K):
δ 2.55 (dd, 3JHH ) 5.2 Hz, 2JPH ) 5.2 Hz, 6H, PCH2), 3.13 (b, 3H,
NH), 6.59 (s, 6H, Ph o-H), 7.27 (s, 3H, Ph p-H). 13C{1H} NMR
(C6D6, 125.8 MHz, 298 K): δ 39.4 (d, JPC ) 12.2 Hz, PCH2),
111.2 and 122.1 (s, Ph o-C and m-C), 112.5. (s, Ph p-C), 132.9 (q,
J ) 32.9 Hz, PhC-F3), 148.9 (d, J ) 5.5 Hz, ipso-C). 31P{1H}
NMR (C6D6, 121.5 MHz, 298 K): δ -32.6 (s). 19F{1H} NMR
(C6D6, 282.1 MHz, 298 K): δ 14.71 (s). Anal. Calcd for
C27H18F18N3P: fw 757.10. C, 42.82; H, 2.40; N, 5.55. Found: C,
43.00; H, 2.49 N, 5.41.
P(CH2NHPh)3 (1b).10 A mixture of P(CH2OH)3 (7.5 g, 0.0605
mol) and aniline (16.5 mL, 3 equiv) were stirred under dynamic
vacuum. The solution became warm after 1 min and was then cooled
after 10 min. Shortly thereafter, the mixture solidified and was left
under vacuum for 2 h. The addition of ether to the mixture and
filtering the resulting solid removed any trace remaining aniline.
The sample was crystallized by cooling a warm saturated toluene
solution sample at -40 °C. The white solid was filtered, rinsed
with pentane, and dried (15.8 g, 75%). 1H NMR (C6D6, 300 MHz,
P(CH2NArMe)3TiNMe2 (2c). A solution of Ti(NMe2)4 (2.63 g,
11.73 mmol) in toluene (50 mL) was added to a solution of 1c
(5.08 g, 11.73 mmol) in 50 mL of toluene. The solution gradually
turned dark red over 24 h. The solution was evaporated to dryness,
and 5 mL of pentane and 10 mL of hexamethyldisiloxane were
added. The solution was filtered, and the dark red solid dried under
vacuum (5.62 g, 92%). X-ray-quality crystals were obtained from
slow evaporation of a pentane solution. 1H NMR (C6D6, 500 MHz,
298 K): δ 2.22 (s, 18H, ArCH3), 3.15 (s, 6H, NMe2), 3.95 (d,
2JPH ) 7.3 Hz, 6H, PCH2), 6.49 (s, 6H, o-H), 6.53 (s, 3H, p-H).
13C{1H} NMR (C6D6, 125.8 MHz, 298 K): δ22.2 (s, ArCH3), 42.8
(s, NMe2), 46.3 (d, JPC ) 19.9 Hz, PCH2), 115.9, 122.7, and 138.7
2
298 K): δ 3.23 (d, JPH ) 4.8 Hz, 6H, PCH2), 3.47 (b, 3H, NH),
6.48 (dd, 6H, Ph o-H), 6.76 (t, 3H, Ph p-H), 7.16 (m, Ph m-H).
13C{1H} NMR (C6D6, 125.8 MHz, 298 K): δ 40.6 (d, JPC ) 12.5
Hz, PCH2), 113.2 and 118.2 (s, Ph o-C and m-C), 117.0. (s, Ph
p-C), 148.5 (d, J ) 4.5 Hz, ipso-C). 31P{1H} NMR (C6D6, 121.5
MHz, 298 K): δ -32.1 (s). Anal. Calcd for C21H24N3P: fw 349.41.
C, 72.19; H, 6.92; N, 12.03. Found: C, 72.55; H, 7.00 N, 11.64.
3
(s, Ph o-C , m-C and p-C), 154.4 (d, J ) 1.6 Hz, ipso-C). 31P-
{1H} NMR (C6D6, 202.5 MHz, 298 K): δ -61.6 (s). Anal. Calcd
for C29H39N4PTi, fw 522.49. C, 66.66; H, 7.52; N, 10.72. Found:
C, 67.02; H, 7.71; N, 11.01.
P(CH2NH-3,5-Me2C6H3)3 (1c). The mixture of P(CH2OH)3
(17.36 g, 0.126 mol) and 3,5-dimethylaniline (45.8 g, 3 equiv) was
stirred under dynamic vacuum. The solution became warm after 1
min and was then cooled after 10 min. Shortly thereafter, the
mixture solidified. Residual 3,5-dimethylaniline was removed by
adding pentane to the mixture and filtering the resulting solid. The
sample was crystallized by cooling a warm saturated toluene
solution to -40 °C. The white solid was filtered, rinsed with
pentane, and dried (42.7 g, 78%). 1H NMR (C6D6, 300 MHz, 298
t
P(CH2NArCF )3TadN Bu (3a). A solution of (Et2N)3Tad
3
NtBu (234.3 mg, 0.5 mmol) in 10 mL of toluene was added to a
solution of 1b (379 mg, 0.5 mmol) in 30 mL of toluene. The
solution was stirred overnight. The solvent was removed under
vacuum, and the remaining pale yellow solid was rinsed with a
small portion of pentane and then dried under vacuum (315 mg,
1
60%). H NMR (C6D6, 300 MHz, 298 K): δ 1.65 (s, 9H, Tad
NCMe3), 3.10 (d, 6H, 2JPH ) 6.7 Hz, PCH2), 7.15 (s, 3H, Ph p-H),
7.54 (s, 6H, Ph o-H). 13C{1H} NMR (C6D6, 125.8 MHz, 298 K):
δ 32.6 (s, 9H, TadNCMe3), 41.8 (d, JPC ) 30.1 Hz, PCH2), 70.4
(s, TadNCMe3), 118.4 and 129.6 (s, Ph o-C and m-C), 125.9 (s,
Ph p-C), 132.8 (q, J ) 32.9 Hz, PhC-F3), 152.5(s, ipso-C). 31P-
{1H} NMR (C6D6, 121.5 MHz, 298 K): δ -108.5 (s). 19F{1H}
NMR (C6D6, 282.1 MHz, 298 K): δ 14.2 (s). Anal. Calcd for
2
K): δ 2.18 (s, 18H, PhCH3), 3.23 (d, JPH ) 5.2 Hz, 6H, PCH2),
3.49 (b, 3H, NH), 6.23 (s, 6H, Ph o-H), 6.42 (s, 3H, Ph p-H).
13C{1H} NMR (C6D6, 125.8 MHz, 298 K): δ22.1 (s, PhCH3), 41.1
(30) Diamond, G. M.; Jordan, R. F.; Petersen, J. L. Organometallics 1996,
15, 4030-4037.
Inorganic Chemistry, Vol. 45, No. 18, 2006 7443

Han et al.
C31H24F18N4PTa‚(0.5 C7H8): C, 39.34; H, 2.7; N, 5.32. Found: C,
39.71; H, 3.30; N, 5.29.
trans-RhCl(CO)(1a)2 (6a). A solution of 1a (60.8 mg, 0.08
mmol) in 0.4 mL of CD2Cl2 was added to [RhCl(CO)2]2 (7.8 mg,
0.02 mmol) in 0.4 mL of CD2Cl2. Gas evolution was observed,
and the solution turned dark orange over the course of 20 min. 1H
NMR (CD2Cl2, 300 MHz, 298 K): δ 3.1 (s, 6H, PCH2), 4.82 (s,
3H, NH), 7.05 (s, 6H, Ph o-H), 7.24 (s, 3H, Ph p-H). 13C{1H}
NMR (CD2Cl2, 125.8 MHz, 298 K): δ 39.1 (s, PCH2), 112.8 (s,
CO), 113.2 and 122.1 (s, Ph o-C and m-C), 118.5 (s, Ph p-C),
132.9 (q, J ) 33.1 Hz, PhC-F3), 148.9 (s, ipso-C). 31P{1H} NMR
(CD2Cl2, 121.5 MHz, 298 K): δ 22.6 (d, JPRh ) 120.1 Hz). 19F-
{1H} NMR (CD2Cl2, 282.1 MHz, 298 K): δ 14.00 (s). IR: 1984.9
P(CH2NPh)3TadNtBu (3b). Prepared in an analogous manner
to 3a using (Et2N)3TadNtBu (234.3 mg, 0.5 mmol) and 1b (173
mg, 0.5 mmol). Yield 389 mg (65%). 1H NMR (C6D6, 500.1 MHz,
298 K): δ 1.62 (s, 9H, TadNCMe3), 3.67 (d, 6H, 2JPH ) 7.3 Hz,
3
3
PCH2), 6.90 (t, 6H, JHH ) 7.3 Hz, Ph o-H), 7.27 (t, 3H, JHH
)
7.8 Hz, Ph p-H), 7.40 (m, 6H, Ph m-H). 13C{1H} NMR (C6D6,
125.8 MHz, 298 K): δ 33.8 (s, TadNCMe3), 42.6 (d, JPC ) 26.8
Hz, PCH2), 69.1 (s, TadNCMe3), 119.1 and 129.1 (s, Ph o-C and
m-C), 121.5 (s, Ph p-C), 152.3 (s, ipso-C). 31P{1H} NMR (C6D6,
202.5 MHz, 298 K): δ -100.9 (s). Anal. Calcd for C25H30N4PTa:
fw 598.45. C, 50.17; H, 5.05; N, 9.36. Found: C, 50.65; H, 5.25;
N, 9.01.
cm-1
.
trans-RhCl(CO)(1b)2 (6b). A solution of 28.0 mg (0.08 mmol)
of 1b in 0.4 mL of CD2Cl2 was added to [RhCl(CO)2]2 (7.8 mg,
0.02 mmol) in 0.4 mL of CD2Cl2. 1H NMR (CD2Cl2, 300.1 MHz,
298 K): δ 3.95 (s, 6H, PCH2), 4.28 (b, 3H, NH), 6.78 (m, 6H, Ph
o-H), 7.20 (t, 3H, Ph p-H), 7.35 (s, 6H, Ph m-H). 13C{1H} NMR
(CD2Cl2, 125.8 MHz, 298 K): δ 39.7 (t, JPC ) 14.5 Hz, PCH2),
114.2 (s, CO), 119.3 and 129.9 (s, Ph o-C and m-C), 128.8 (s, Ph
p-C), 148.2 (m, ipso-C). 31P{1H} NMR (CD2Cl2, 202.5 MHz, 298
P(CH2NArMe)3TadNtBu (3c). Prepared in an analogous manner
to 3a using (Et2N)3TadNtBu (234.3 mg, 0.5 mmol) and 1c (215
mg, 0.5 mmol) and a reaction time of 72 h. Yield 204.6 mg (60%).
X-ray-quality crystals were obtained from slow evaporation of the
1
benzene solution. H NMR (C6D6, 300 MHz, 298 K): δ 1.71 (s,
2
9H, TadNCMe3), 2.32 (s, 18H, ArCH3), 3.73 (d, JPH ) 6.7 Hz,
K): δ 23.7 (d, JPRh ) 118.1 Hz). IR: 1976.3 cm-1
.
6H, PCH2), 6.61 (s, 6H, o-H), 7.11 (s, 3H, p-H). 13C{1H} NMR
(C6D6, 125.8 MHz, 298 K): δ21.9 (s, ArCH3), 33.6 (s, 9H, Tad
NCMe3), 42.7 (d, JPC )26.3 Hz, NMe2), 68.9 (s, TadNCMe3),
116.2 (s, Ph o-C), 117.9 (s, Ph m-C), 138.7 (s, Ph p-C), 152.5(s,
ipso-C). 31P{1H} NMR (C6D6, 202.5 MHz, 298 K): δ -100.1 (s).
Anal. Calcd for C31H42N4PTa: fw 682.61. C, 54.55; H, 6.20; N,
8.21. Found: C, 54.07; H, 6.11; N, 8.77.
trans-RhCl(CO)(1c)2 (6c). A solution of 1c (34.4 mg, 0.08
mmol) in 0.4 mL of CD2Cl2 was added to[RhCl(CO)2]2 (7.8 mg,
1
0.02 mmol) in 0.4 mL of CD2Cl2. H NMR (CD2Cl2, 300 MHz,
298 K): δ 2.20 (s, 18H, PhCH3), 3.93 (s, 6H, PCH2), 4.24 (b, 3H,
NH), 6.32 (s, 6H, Ph o-H), 6.43 (s, 3H, Ph p-H). 13C{1H} NMR
(CD2Cl2, 125.8 MHz, 298 K): δ21.7 (s, PhCH3), 39.6 (t, JPC
)
(CO)3Ni(PCH2NArMe)3TiNMe2 (4). Excess Ni(CO)4 was vacuum-
transferred onto a solution of 2c (1.25 g, 2.87 mmol) in 50 mL of
toluene. The dark red solution was stirred 5 min and then evaporated
to dryness to provide a dark red product (1.77 g, 93%). The product
was stable for short durations in CH2Cl2, as judged by 31P{1H}
NMR spectroscopy, and the IR spectrum of a 0.05 M solution was
obtained in this solvent. Solutions kept at room temperature are
not stable and gradually undergo ligand redistribution with loss of
13.4 Hz, PCH2), 116.0 (s, CO), 112.0 and 121.2 (s, Ph o-C and
m-C), 139.6 (s, Ph p-C), 148.3 (t, ipso-C). 31P{1H} NMR (CD2-
Cl2, 121.5 MHz, 298 K): δ 23.5 (d, JPRh ) 116.9 Hz). IR: 1973.2
cm-1
.
trans-RhCl(CO)(2a)2 (7a). A solution of 2a (64.1 mg, 0.08
mmol) in 0.4 mL of CD2Cl2 was added to [RhCl(CO)2]2 (7.8 mg,
1
0.02 mmol) in 0.4 mL of CD2Cl2. H NMR (CD2Cl2, 300 MHz,
298 K): δ 3.5 (s, 6H, NCH3), 4.8 (s, PCH2), 7.29 (s, 6H, Ph o-H),
7.54 (s, 3H, Ph p-H). 13C{1H} NMR (CD2Cl2, 125.8 MHz, 298
K): δ 42.7 (s, TiNCH3), 49.3 (s, PCH2), 115.2 (s, CO), 113.4 and
122.1 (s, Ph o-C and m-C), 117.3 (s, Ph p-C), 133.1 (q, J ) 32.8
Hz, PhC-F3), 153.2(s, ipso-C). 31P{1H} NMR (CD2Cl2, 121.5 MHz,
298 K): δ 3.8 (d, JPRh ) 130.3 Hz). 19F{1H} NMR (CD2Cl2, 282.1
1
Ni(CO)4 and thus should be handled with care. H NMR (C6D6,
500 MHz, 298 K): δ 2.17 (s, 18H, ArCH3), 3.06 (s, 6H, NMe2),
4.07 (s, 6H, PCH2), 6.46 (s, 6H, o-H), 6.52 (s, 3H, p-H). 13C{1H}
NMR (C6D6, 125.8 MHz, 298 K): δ22.0 (s, ArCH3), 42.9 (s,
NMe2), 52.5 (d, JPC ) 15.5 Hz, PCH2), 116.1, 123.6, and 139.1 (s,
MHz, 298 K): δ 14.3 (s). IR: 1988.1 cm-1
.
3
Ph o-C , m-C and p-C), 153.8 (d, JPC ) 6.9 Hz, ipso-C), 196.3
2
(d, JPC ) 1.1 Hz, Ni(CO)3). 31P{1H} NMR (C6D6, 202.5 MHz,
trans-RhCl(CO)(2b)2 (7b). A solution of 2b (35.2 mg, 0.08
mmol) in 0.4 mL of CD2Cl2 was added to 7.8 mg (0.02 mmol) of
[RhCl(CO)2]2 in 0.4 mL of CD2Cl2. 1H NMR (CD2Cl2, 300 MHz,
298 K): δ 4.1 (s). Anal. Calcd for C32H39N4O3PTi: fw 665.21; C,
57.78; H, 5.91; N, 8.42. Found: C, 58.01; H, 5.94; N, 8.39. IR:
(CH2Cl2, 0.05M) 2073.7 cm-1 (s, A1), 2041.0 cm-1 (w), 2000.0
cm-1 (br, E).
3
298 K): δ 3.3 (s, 6H, TiNMe2), 4.6 (s, PCH2), 6.82 (d, 6H, JHH
) 7.8 Hz, Ph o-H), 6.89 (t, 3H, Ph p-H), 7.30 (t, 6H, Ph m-H).
13C{1H} NMR (CD2Cl2, 125.8 MHz, 298 K): δ 43.0 (s, TiNMe2),
49.7 (s, PCH2), 117.5 (s, CO), 117.7 and 129.7 (s, Ph o-Cand m-C),
121.6 (s, Ph p-C), 153.5 (m, ipso-C). 31P{1H} NMR (CD2Cl2, 202.5
(CO)2Ni[P(CH2NArMe)3TiNMe2]2 (5). Solid 1c (482.8 mg, 0.924
mmol) was added to a solution of 4 (614.9 mg, 0.924 mmol) in 50
mL of toluene. The solution was stirred for 48 h and evaporated to
dryness, and 15 mL of pentane was added. The solution was filtered
and the remaining dark red solid was rinsed with a small portion
of pentane and then dried under vacuum. The complex is slightly
soluble in pentane, and X-ray crystals were obtained by cooling a
MHz, 298 K): δ 15.7 (d, JPRh ) 125.8 Hz). IR: 1979.6 cm-1
.
trans-RhCl(CO)(2c)2 (7c). A solution of 2c (42.0 mg, 0.08
mmol) in 0.4 mL of CD2Cl2 was added to [RhCl(CO)2]2 (7.8 mg,
1
0.02 mmol) in 0.4 mL of CD2Cl2. H NMR (CD2Cl2, 300 MHz,
1
298 K): δ 2.28 (s, 18H, ArCH3), 3.26 (s, 6H, NMe2), 4.56(s, 6H,
PCH2), 6.46 (s, 6H, o-H), 6.47 (s, 3H, p-H). 13C{1H} NMR (CD2-
Cl2, 125.8 MHz, 298 K): δ21.9 (s, ArCH3), 43.3 (s, NMe2), 49.6-
(s, PCH2), 112.1 (s, CO), 115.6, 123.2, and 139.2 (s, Ph o-C , m-C
and p-C), 153.5 (s, ipso-C). 31P{1H} NMR (CD2Cl2, 202.5 MHz,
pentane solution to -40 °C. H NMR (C6D6, 500 MHz, 298 K):
δ 2.17 (s, 18H, ArCH3), 3.06 (s, 6H, NMe2), 1H NMR (C6D6, 500
MHz, 298 K): δ 2.15 (s, 18H, ArCH3), 3.12 (s, 6H, NMe2), 4.37
(s, 6H, PCH2), 6.51 (s, 3H, p-H), 6.56 (s, 6H, o-H). 13C{1H} NMR
(C6D6, 125.8 MHz, 298 K): δ 22.0 (s, ArCH3), 42.9 (s, NMe2),
54.0 (vt, JPC ) 15.5 Hz, PCH2), 116.0, 123.4, and 139.0 (s, Ph
o-C, m-Cand p-C), 153.8 (d, 3JPC ) 6.9 Hz, ipso-C), 190.0 (t, 2JPC
) 1.1 Hz, Ni(CO)3). 31P{1H} NMR (C6D6, 202.5 MHz, 298 K): δ
7.03 (s). Anal. Calcd for C60H78N8NiO2P2Ti2: fw 1159.69; C,
62.14; H, 6.78; N, 9.66. Found: C, 62.33; H, 6.96; N, 9.47.
298 K): δ 18.51 (d, JPRh ) 122.5 Hz). IR: 1974.8 cm-1
.
trans-RhCl(CO)(3a)2 (8a). A solution of 3a (80.5 mg, 0.08
mmol) in 0.4 mL of CD2Cl2 was added to 7.8 mg (0.02 mmol) of
[RhCl(CO)2]2 in 0.4 mL of CD2Cl2. 1H NMR (CD2Cl2, 300 MHz,
298 K): δ 1.59 (s, 9H, TadNCMe3), 4.90 (s, PCH2), 7.55 (s, 3H,
7444 Inorganic Chemistry, Vol. 45, No. 18, 2006

Diligating Tripodal Amido-Phosphine Ligands
Ph p-H), 7.82 (s, 6H, Ph o-H). 13C{1H} NMR (CD2Cl2, 125.8 MHz,
298 K): δ 32.9 (s, 9H, TadNCMe3), 53.3 (d, JPC ) 30.1 Hz,
PCH2), 72.2 (s, TadNCMe3), 116.2 and 129.6 (s, Ph o-C and m-C),
125.9 (s, Ph p-C), 132.8 (q, J ) 33.2 Hz, PhC-F3), 152.8(t, ipso-
C). 31P{1H} NMR (CD2Cl2, 121.5 MHz, 298 K): δ -34.2 (d, JPRh
) 143.6 Hz). 19F{1H} NMR (CD2Cl2, 282.1 MHz, 298 K): δ 14.9
and the WinGX36 software package, and thermal ellipsoid plots
were produced using ORTEP32.37 The thermal parameters for the
carbonyl fragment in 8c were modeled isotropically due to problems
arising from its 3-fold disorder.
Calculations. Ab initio DFT calculations were performed using
the hybrid functional B3LYP38 method with the Gaussian 03
package.39 The basis functions used were the LANL2DZ set,
provided in the Gaussian 03 program.
(s). IR: 1990.5 cm-1
.
trans-RhCl(CO)(3b)2 (8b). A solution of 3b (48.0 mg, 0.08
mmol) in 0.4 mL of CD2Cl2 was added to[RhCl(CO)2]2 (7.8 mg,
0.02 mmol) in 0.4 mL of CD2Cl2. 1H NMR (CD2Cl2, 300.1 MHz,
298 K): δ 1.59 (s, 9H, TadNCMe3), 4.82 (s, PCH2), 6.95 (t, 6H,
3JHH ) 7.3 Hz, Ph o-H), 7.3 (t, 3H, 3JHH ) 7.8 Hz, Ph p-H), 7.44
(d, 6H, Ph m-H). 13C{1H} NMR (CD2Cl2, 125.8 MHz, 298 K): δ
32.9 (s, TadNCMe3), 46.7 (s, PCH2), 69.8 (s, TadNCMe3), 117.7
(s, CO), 118.4 and 128.5(s, Ph o-C and m-C), 121.3 (s, Ph p-C),
151.0 (s, ipso-C). 31P{1H} NMR (CD2Cl2, 202.5 MHz, 298 K): δ
Acknowledgment is made to the National Sciences and
Engineering Council (NSERC) of Canada and the Ontario
Research and Development Challenge Fund (University of
Windsor Centre for Catalysis and Materials Research) for
their financial support.
Supporting Information Available: Crystallographic data in
the form of cif files for 1c, 2b, 3c, 5, and 8c; energy and optimized
geometry coordinates for DFT calculation on 3b and crystal-
lographic data. This material is available free of charge via the
Internet at http://pubs.acs.org.
-32.8 (d, JPRh ) 138.11 Hz). IR: 1986.7 cm-1
.
trans-RhCl(CO)(3c)2 (8c). A solution of 3c (54.6 mg, 0.08
mmol) in 0.4 mL of CD2Cl2 was added to 7.8 mg (0.02 mmol) of
[RhCl(CO)2]2 in 0.4 mL of CD2Cl2. X-ray-quality crystals were
obtained from slow evaporation of the CD2Cl2 solution at -40 °C.
1H NMR (CD2Cl2, 300 MHz, 298 K): δ 1.63 (s, 9H, TadNCMe3),
2.32 (s, 18H, ArCH3), 4.77 (s, 6H, PCH2), 6.61 (s, 6H, o-H), 7.08
(s, 3H, p-H). 13C{1H} NMR (CD2Cl2, 125.8 MHz, 298 K): δ21.7
(s, ArCH3), 33.5 (s, TadNCMe3), 47.4 (s, NMe2), 70.4 (s, Tad
NCMe3), 116.3 (s, CO), 116.9 (s, Ph o-C), 123.9 (s, Ph m-C), 138.9
(s, Ph p-C), 151.9 (s, ipso-C). 31P{1H} NMR (CD2Cl2, 202.5 MHz,
298 K): δ -32.3 (d, JPRh ) 136.9 Hz). IR: 1986.6 cm-1. Anal.
Calcd for C63H84N8OClP2Ta2: C, 49.40; H, 5.53; N, 7.32. Found:
C, 49.09; H, 5.64; N, 7.27.
X-ray Crystallography. The X-ray structures were obtained at
low temperature, with each crystal covered in Paratone and placed
rapidly into the cold N2 stream of the Kryo-Flex low-temperature
device. The data were collected using the SMART31 software on a
Bruker APEX CCD diffractometer using a graphite monochromator
with Mo KR radiation (λ ) 0.71073 Å). A hemisphere of data was
collected using a counting time of 10-30 s per frame. Details of
crystal data, data collection, and structure refinement are listed in
Table 1. Data reductions were performed using the SAINT32
software, and the data were corrected for absorption using SAD-
ABS.33 The structures were solved by direct methods using SIR9734
and refined by full-matrix least-squares on F2 with anisotropic
displacement parameters for the non-H atoms using SHELXL-9735
IC060692D
(32) SAINTPlus, Data reduction and correction program; Bruker AXS,
Inc.: Madison, WI, 2001.
(33) SADABS, An empirical absorption correction program; Bruker AXS,
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