Ruthenaphosphaalkenyls: Synthesis, Structures, and Their Conversion to η2-Phosphaalkene Complexes

Article abstract of DOI:10.1021/om5012177

The ruthenaphosphaalkenyls [Ru{P = CH(SiMe₂R)}Cl(CO)(PPh₃)₂] (R = Me, Ph, Tol) have been prepared in good yield by the facile hydroruthenation of the respective phosphaalkynes, RMe₂SiC≡P, with [RuHCl(CO)-(PPh₃)₃]; all three compounds have been structurally characterized in the solid state. Complemented by DFT studies of these, and the precedent [Ru{P = CH(^tBu)}Cl(CO)(PPh₃)₂], the phosphaalkenyl moieties have been established unequivocally to behave as one-electron donors to the coordinately unsaturated, 15-electron "RuCl(CO)(PPh₃)₂" fragment, corroborating an earlier demonstration of nucleophilic character at phosphorus within the tert-butyl system. Notwithstanding, the ruthena-phosphaalkenyls are shown to react with the nucelophiles Lipz′ (pz′ = pz, pz, pz^H,CF3, pz^Me,CF3) to afford the η¹,η²-chelated pyrazolylphosphaalkene complexes [Ru{η¹-N:η²-P,C-P(pz′) = CH(R)}(CO)(PPh₃)₂], which feature a three-membered metallacyclic (Ru-C-P) core. The nature of these novel compounds is discussed, alongside preliminary insight into the process by which they are formed. (Chemical Equation Presented).

Full text of DOI:10.1021/om5012177

Article
pubs.acs.org/Organometallics
Ruthenaphosphaalkenyls: Synthesis, Structures, and Their
Conversion to η2‑Phosphaalkene Complexes
Victoria K. Greenacre,† Nicola Trathen,† and Ian R. Crossley*
Department of Chemistry, University of Sussex, Falmer, Brighton BN1 9QJ, U.K.
S
* Supporting Information
ABSTRACT: The ruthenaphosphaalkenyls [Ru{PCH-
(SiMe2R)}Cl(CO)(PPh3)2] (R = Me, Ph, Tol) have been
prepared in good yield by the facile hydroruthenation of the
respective phosphaalkynes, RMe2SiCP, with [RuHCl(CO)-
(PPh3)3]; all three compounds have been structurally charac-
terized in the solid state. Complemented by DFT studies of
these, and the precedent [Ru{PCH(tBu)}Cl(CO)(PPh3)2],
the phosphaalkenyl moieties have been established unequivocally
to behave as one-electron donors to the coordinately unsaturated,
15-electron “RuCl(CO)(PPh3)2” fragment, corroborating an
earlier demonstration of nucleophilic character at phosphorus
within the tert-butyl system. Notwithstanding, the ruthena-
Me,CF3
phosphaalkenyls are shown to react with the nucelophiles Lipz′ (pz′ = pz, pz*, pzH,CF , pz
) to afford the η1,η2-chelated
3
pyrazolylphosphaalkene complexes [Ru{η1-N:η2-P,C-P(pz′)CH(R)}(CO)(PPh3)2], which feature a three-membered metal-
lacyclic (Ru−C−P) core. The nature of these novel compounds is discussed, alongside preliminary insight into the process by
which they are formed.
metallaphosphaalkenyls (type A). The first such compound,
[CpFe(CO)2{PC(SiMe3)}tBu], described in 1985,6 was
obtained through an extension of Becker’s methodology, via
INTRODUCTION
■
The chemistry of low-coordinate phosphacarbons has been an
active area of research for over four decades,1 and continues to
be a topic of widespread interest.2 Amidst this constantly
developing field, phosphaalkenes (RPCR′R″) have long held
particular importance, being among the earliest phospha-
carbons to be studied in detail.3 In an organometallic context,
while both the η1- and η2-coordination complexes of phospha-
alkenes have been studied,4 albeit less extensively so for the
latter case, a more prevalent interest has surrounded the
metallaphosphaalkenes (A−E, Chart 1) in which at least one
substituent on the “PC” moiety is replaced by either a
transition metal fragment or main group metal.5
t
the interaction of BuC(O)Cl with the bis(trimethylsilyl)-
phosphide complex [CpFe(CO)2P(SiMe3)2].7 Subsequently, a
range of such compounds was similarly obtained (Chart 2).8
Chart 2. Representative P-Metallaphosphaalkenyls
With the exception of those of type E, all possible
metallaphosphaalkene motifs have been realized, albeit that
work has been overwhelmingly focused on the P-metalla- (type
A) and C-metalla- (type B) systems. These constitute intriguing
extensions of the phosphacarbon paradigm “the carbon copy” in
an organometallic context, particularly with respect to P-
Other prevalent synthetic routes have included (i) metathesis
of P-halogenophosphaalkenes with carbonylmetallates,9 (ii)
metathesis of P-silylphosphaalkenes with transition metal
halides (LnMX),10 and (iii) oxidative addition of P-function-
alized (Cp*, Cl) phosphaalkenes to low-valent metal fragments
(M(NCMe)3(CO)3, where M = Cr, Mo, W; “Fe(CO)5”;
Ni(PR3)2(cod); Pt(PPh3)2(C2H4)).11 The reduction of
phosphaalkynes within the coordination sphere of a transition
Chart 1. Metallaphosphaalkenyl Motifs
Special Issue: Mike Lappert Memorial Issue
Received: November 30, 2014
© XXXX American Chemical Society
A
DOI: 10.1021/om5012177
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
metal has also found some utility to this end, albeit typically
accompanied by oligomerization of phosphaalkyne units.12
Notably, however, in 1996 Hill and Jones described the facile,
stoichiometric reduction of tBuCP by the ruthenium hydride
complex [RuHCl(CO)(PPh3)3].13 Akin to the established
alkyne hydroruthenation protocols,14 this afforded the ruthena-
phosphaalkenyl [Ru(PCHtBu)Cl(CO)(PPh3)2] (1),13,15 the
thiocarbonyl analogue of which was similarly obtained,
alongside analogues derived from AdCP.15 Jones subse-
quently reported the successful double hydroruthenation of his
bicyclo[2.2.2]octane-1,4-diphosphaalkyne,16 though Hill’s at-
tempts to prepare an osmium analogue of 1 were thwarted by
The identities of 2−4 follow convincingly from analytical and
spectroscopic data. Thus, the 31P NMR spectra exhibit doublet-
based resonances associated with the retained PPh3 ligands (δP
34.6, 2; 33.7, 3; 33.7, 4), with mutual coupling (8 Hz) to
heavily deshielded resonances (δP 548.5, JPH = 21 Hz, 2; 553.8,
JPH = 20 Hz, 3; 552.6, JPH = 20 Hz, 4) that lie in a region
characteristic of P-metallaphosphaalkenyls.8−12 The latter
collapse to triplets in the 31P{1H} NMR spectra, consistent
with loss of the scalar interaction to their respective vinylic
proton, the resonances for which are assigned on the basis of
31P−1H HMBC spectra (δH 7.28, 2; 7.40, 3; 7.41, 4), alongside
their correlation to the carbon (δC 168.0, 2; 163.7, 3; 165.2, 4)
and silicon (δSi −9.4, 2; −14.3, 3; −14.4, 4) centers of the
phosphaalkenyl moiety. Retention of the carbonyl ligand is in
each case confirmed by infrared data (νCO = 1920 cm−1, 2;
1938 cm−1, 3; 1936 cm−1, 4), the associated 13C{1H} NMR
resonances of which (δC 203.0, 2; 201.9, 3; 202.5, 4) are also
observed.
It is noteworthy that the low-coordinate phosphorus centers
of 2−4 are significantly more deshielded than that of 1 (δP
450.4).13 We attribute this to the differing substituent at the
adjacent alkenic carbon (SiR3 vs tBu), given the similar disparity
noted between the parent phosphaalkynes RCP (δP for R =
Ph, −67; SiMe3, 98.7; SiMe2Ph, 102.7; SiMe2Tol, 103.3).
However, one cannot immediately discount the possibility of
differing coordination modes; indeed, though compound 1 was
concluded to involve a one-electron phosphaalkenyl ligand
(vide supra),15 the lack of structural verification, alongside a
noted strong trans influence, do not fully preclude the
possibility of some phosphavinylidene character (vide infra).
From a structural stand-point, the silyl derivatives 2−4
(Figures 1−3, Table 1) would seem consistent with the
t
its facile incorporation of a second equivalent of BuCP to
afford a phosphaalkenyl-phosphaalkene complex.17
Compound 1 is notable in featuring both a relatively
unencumbered phosphaalkenyl moiety (cf. the classical use of
sterically demanding and/or π-dative substituents to confer
stability) and apparent unsaturation at the metal center. For
early transition metals, such unsaturation results in additional
donation of the phosphaalkenyl lone pair to the metal, viz.
adoption of a three-electron phosphavinylidene ligation
mode,9a,c,18 resulting in electrophilicity of the phosphorus
center. However, while structural data for 1 have not been
described, the demonstration of nucleophilicity at phospho-
rus,19 in a series of 1,2 additions across the P−Ru linkage, was
deemed characteristic of a “bent” one-electron P-phosphavinyl
ligand15 within an overall 16-electron complex; the latter was
somewhat supported by isolation of 18-electron complexes
upon addition of a series of two-electron donors (CO, CNR),
though a significant trans influence was noted for the
phosphaalkenyl.13,15
Notwithstanding, while investigating an analogue of 1, viz.
[Ru{PCH(SiMe3)}Cl(CO)(PPh3)2] (2), we noted unex-
pected ambiphilic behavior. Thus, as we have recently
communicated,20 while 2 readily undergoes 1,2 additions
consistent with a nucleophilic phosphorus center, its interaction
with the pyrazolates [pz′]− (pz′ = pz, pz*) also results in
functionalization at phosphorus. Herein, we describe further
investigation of this unusual behavior, including a structural
study of the parent phosphaalkenyls.
RESULTS AND DISCUSSION
■
Ruthenaphosphaalkenyl Complexes. In a manner
similar to that previously described for 1,13 the novel
ruthenaphosphaalkenyls [Ru{PCH(SiMe2R)}Cl(CO)-
(PPh3)2] (R = Me 2, Ph 3, p-Tol 4) were obtained from the
reaction of [RuHCl(CO)(PPh3)3] with excess of the respective
phosphaalkyne RMe2SiCP21,22 (Scheme 1), the latter
generated as toluene solutions by the double dehydrochlorina-
tion of RMe2SiCH2PCl2.23
Figure 1. Molecular structure of 2 in molecules of the Et2O solvate;
50% thermal ellipsoids, hydrogen atoms omitted for clarity.
a
Scheme 1. Synthesis of Phosphaalkenyls 2−4
phosphaalkenyl being engaged in one-electron ligation to the
metal. Thus, a distinctly “bent” geometry is noted for the
phosphaalkenyl moiety (∠Ru−P−C = 121.3(2)−124.4(4)°;
∠P−C−Si = 122.5(7)−125.6(2)°) with no evidence for
linearization. The Ru−P linkages are relatively short (dRuP
=
2.226(2)−2.2503(10) Å) in comparison to ruthenium-
phosphido complexes (2.382−2.512 Å24), those of the η1-
phosphaalkene complexes [Ru{η1-P(E)CH(R)}Cl2(CO)-
19b
(PPh3)2] (R = Bu, E = Au(PPh3), HgFc;19e R = SiMe3, E
= HgPh;20 dRu−P = 2.256(2)−2.296(2) Å) and that reported for
Hill’s 18-electron phosphaalkenyl [Ru{PCHtBu}(O2CH)-
t
a
Reagents and conditions: (i) 2AgOTf, 2DABCO, toluene; (ii)
[RuHCl(CO)(PPh3)3], CH2Cl2 (L = PPh3).
B
DOI: 10.1021/om5012177
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
PC bonds (dPC = 1.655(2)−1.660(11) Å) are comparable
to those of the η1-phosphaalkene complexes (1.662(5)−
1.69(2) Å), Hill’s 18-electron system (1.640(8) Å), and
phosphaalkenyls more generally (1.65−1.75 Å).24 It is thus
fair to conclude a lack of any higher-order character for the
Ru−P linkage; this is also borne out by DFT studies (vide
infra).
The molecular geometries are otherwise largely unremark-
able. The interligand angles about ruthenium (∠Cl−Ru−CO =
162.68(8)−163.56(12)°; ∠PPR −Ru−PPR 166.62(2)−
3
3
167.18(7)°) are typical of square-based pyramidal Ru(II), and
CO distances are similarly consistent. The phosphaalkenyl
moieties are in each case essentially coplanar with the carbonyl
ligand (ϕ = 8.2(6)°, 2; 17.93(10)°, 3; 17.89(17)°, 4), with
which they also adopt a cis conformation, as was observed for
[Ru{PCHtBu}(O2CH)(CO)(PPh3)2]15 and has been pre-
viously noted for analogous ruthenium vinyl complexes.24,26 In
the latter cases, this has been attributed to achieving optimal
dπ→π* retro-donation to both the carbonyl and alkenyl ligands,
coupled with a consequentially significant barrier to rotation
about the Ru−Calkene linkage, and a marginal thermodynamic
preference for the cis rather than trans arrangement (ca. 2 kcal
mol−1) of the two ligands.27 A comparable situation would
seem likely for the phosphaalkenyl analogues.
Figure 2. Molecular structure of 3; 50% thermal ellipsoids, hydrogen
atoms omitted for clarity.
DFT Studies. The ground-state geometries of complexes 1−
4 were optimized using DFT methods, commencing either
from the solid-state data (2−4) or from hypothetical models (1
and 2); in each case, geometries were obtained that compare
well with the experimental (solid-state) structures of 2−4 (see
Supporting Information).
The calculated IR data (νCO) and 31P NMR isotropic
shielding tensors (lanl2dz on Ru; 6-31G** all other atoms) of
1−4, show moderate agreement with experimental data, but do
closely reflect the observed trends (Table 2). In particular, the
Table 2. Comparative Calculated and Experimental IR and
NMR Data
Figure 3. Molecular structure of 4; 50% thermal ellipsoids, hydrogen
νCO/cm−1
abc
δP (Palkene)
atoms omitted for clarity.
d
be
,
be
,
f
,
,
calcd
exptl
B3LYP
PBEPBE
exptl
a
Table 1. Selected Geometric Data for Compounds 2−4
1
2
3
4
1933.4
1938.5
1952.2
1951.8
1929
1920
1938
1936
482.0
584.4
606.8
604.7
455.4
537.2
558.0
557.9
450.4
548.5
553.8
552.6
b
2
3
4
Ru−Palkenyl
Ru−CCO
PC
2.226(2)
1.735(9)
1.660(11)
1.183(12)
124.4(4)
122.5(7)
167.18(7)
2.2468(5)
1.835(2)
2.2504(8)
1.824(3)
a
b
c
1.665(2)
1.655(3)
B3LYP. lanl2dz on Ru; 6-31G** on all other atoms. Frequency
scaling factor of 0.961 applied. CH2Cl2 solutions. Using GIAO
method, referenced against H3PO4 at the same level of theory. As
CD2Cl2 solutions.
d
e
CO
1.143(3)
1.163(4)
f
Ru−PC
PC−Si
121.49(7)
124.88(12)
166.615(6)
121.31(11)
125.64(17)
166.84(3)
PPR −Ru−PPR
3
3
computed 31P NMR shifts for the Palkenyl centers indicate
appreciably greater shielding within 1 (ΔδP ≈ −100 ppm w.r.t.
2) compared with the silyl systems; this substantiates the
notion that this feature is of purely electronic origin (i.e., tBu vs
SiMe2R) rather than being the result of any geometric
distinctiveness. Indeed, attempts to optimize the geometry of
1 using a phosphavinylidene model resulted in relaxation to the
phosphaalkenyl motif (Figure 4), which exhibits no evidence
for involvement of the lone pair in metal binding.
For all four complexes the frontier orbitals are dominated by
the metal and phosphaalkenyl fragments (Figure 5). Thus, for
2−4, the HOMO involves appreciable bonding overlap
between ruthenium and the phosphaalkenyl σ-framework, and
also incorporates the phosphorus lone pair. A somewhat lesser
Cl−Ru−CCO
159.0(3)
162.68(6)
163.57(10)
a
Bond distances (Å) and angles (deg) with estimated standard
b
deviations in parentheses. The structure for 2 suffers from some
disorder around the carbonyl carbon; associated parameters should be
interpreted with caution.
(CO)(PPh3)2] (2.295(2) Å).15 They are also shorter than
those reported by Peters for [Ru{κ4-Si(C6H4PPh2)3}{PR2)] (R
= Ph, 2.2700(3) Å; iPr, 2.2592(4) Å), which exhibit appreciable
RuP double bond character, as evidenced by planarity of the
Ru-PR2 unit.25 However, the distances of 2−4 do compare well
with the Ru←PR3 distances recorded for other square-based
pyramidal ruthenium(II) complexes (2.16−2.47 Å),24 while the
C
DOI: 10.1021/om5012177
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
pz, pz*) to afford in each case high yield of a single species (5−
10, Scheme 2). As we have previously communicated,20 the
a
Scheme 2. Reactions of 1−3 with Lipz′ (pz′ = pz, pz*)
Figure 4. Optimized core geometry of 1, with phenyl rings and
ancillary hydrogen atoms omitted for clarity. Selected bond distances
(Å) and angles (deg): Ru−P 2.318, PC 1.680, Ru−CO 1.846,
CO 1.166, Cl−Ru−C 159.02, Ru−P−C 118.05 PC−C 126.54.
a
Reagents and conditions: (i) Lipz′ (pz′ = pz, pz*), THF, rt, 1 h.
Comparable methodology is used to obtain 11−14 from LipzCF and
3
LipzMe,CF
.
3
connectivity of compounds 7 and 8 was established from X-ray
diffraction data, which were readily reconciled with character-
istic features of the multinuclear NMR spectra. Thus, while 5, 6,
9, and 10 have yet to yield X-ray-quality crystals, their
comparable nature is apparent from their spectroscopic
signatures (Table 3). In all cases three (1:1:1) mutually
coupling resonances are apparent in the 31P{1H} NMR spectra,
in a region (10−60 ppm) typically characteristic of saturated
phosphorus centers, while the heavily deshielded phospha-
alkenyl resonance has been lost. Notwithstanding, retention of
the tBu (5, 6) or SiMe2R (7−10) moieties is apparent from the
1
1H NMR spectra (supported by H− 29Si correlation for 7−
10), the respective resonances integrating consistently against
those in the aromatic region, which indicate retention of both
PPh3 ligands. Moreover, 1H and 13C NMR resonances
associated with the P−CH unit are observed, identified on
the basis of correlation experiments, albeit in significantly more
shielded positions; the “P−CHR” unit can thus be concluded to
be intact, albeit no longer phosphaalkenyl in nature. Finally,
retention of the carbonyl ligand is confirmed by both
characteristic infrared and 13C{1H} NMR data.
Figure 5. Representative frontier orbitals for compound 2.
component of dπ→π*(CO) retro-donation is also apparent.
The HOMO−1, which lies essentially orthogonal to the
HOMO (with respect to the metal d orbitals and alkenyl
moiety) and around 0.1 eV lower in energy, is composed of
out-of-phase mixing of the metal dπ orbital and phosphaalkenyl
π-system, and in the cases of 3 and 4 a small contribution from
the arene π-orbitals. For 1, the HOMO and HOMO−1 are
reversed, though again close in energy (0.09 eV) and with the
same general composition.
The precise nature of the three-membered (Ru−C−P) cyclic
core of these compounds is a matter of intrigue. The
crystallographic data20 for 7 and 8 indicated significant
pyramidalization about the Calkene center (∠P−C−H =
112.8°, ∠Si−C−H = 112.8°, ∠P−C−Si = 116.7°) with
concomitant lengthening of the P−C linkage (1.793(6) Å),
superficially consistent with a ruthenaphosphirane geometry.
1
Indeed, H and 13C NMR spectroscopic data would also seem
In all cases the LUMO is appreciably separated from the
HOMO (3.76−3.87 eV), largely metal-based, and accessible to
nucleophiles through the basal plane. Interestingly, for 2−4 the
LUMO+1, which is only modestly higher in energy (ca. 0.6
eV), involves an appreciable contribution from the phospha-
alkenyl π* orbital; the equivalent orbital of 1 is at LUMO+2, ca.
0.8 eV above the LUMO. This is significant, given that NBO
calculations indicate an appreciable δ+ character at the alkenyl
phosphorus atom (0.55−0.76). Taken together, these features
would seem to imply the possibility of at least some
electrophilic character for this center, alongside the unequiv-
ocally established nucleophilicity associated with the accessible
lone pair (HOMO). This has potential implications with
respect to the noted ambiphilicity of these systems (vide
infra).20
to support such formalism, the “P−CH” moiety exhibiting
shifts consistent with a saturated system (for 7, δH 1.59, δC
47.5; for 8, δH 1.62, δC 44.9). The C−H coupling magnitudes
for the “P−CH” moiety (JCH = 137 Hz, 7; 123 Hz, 8) are,
however, more ambiguous, being intermediate between those
characteristic of “sp3 ” (cf. 125 Hz in CH4) and “sp2 ” (cf. 156
Hz in C2H4)28 models; moreover, minimal perturbation of the
P−C coupling magnitude (1JPC ≈ 79 Hz; cf. 1JPC = 77 Hz in 3)
is also superficially consistent with retention of appreciable
“sp2” character. Intermediate character is also reflected in the
fact the P−C linkage remains shorter than both a typical
P(sp3)−C(sp3) single bond (1.855(19) Å)29 and those of other
known phosphiranes (1.8−1.9 Å).24
The spectroscopic data for all compounds 5−10 show a
consistent trend, though it is again noted that replacement of
silyl with tert-butyl results in significant deshielding of the “P−
CH” unit (cf. 1 vs 2−4). This is markedly more pronounced
than for the parent phosphaalkenyls, which may suggest a more
Synthesis of η2-Phosphaalkene Complexes. The
ruthenaphosphaalkenyls 1−3 all react readily, in THF solution,
with single equivalences of the lithium pyrazolates Lipz′ (pz′ =
D
DOI: 10.1021/om5012177
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
a
Table 3. Spectroscopic Data for η2-Phosphaalkene Complexes 5−14
b
c
c
δP
δC
δH
d
e
R
R′
R″
PC
PPh3
PC
PCH (1JCH/Hz)
νCO /cm−1
kCO/N cm−1
5
tBu
tBu
H
H
38.8
14.7
58.7
32.9
57.0
32.3
76.6
64.6
74.9
62.7
44.2, 42.5
45.5, 41.4
46.6, 42.0
46.6, 39.2
47.0, 41.7
47.0, 38.9
47.7, 41.5
46.9, 38.4
48.0, 41.3
47.2, 38.3
81.6
79.8
47.6
44.9
45.1
41.8
47.1
45.2
46.7
41.8
2.84
1906
1902
1907
1906
1913
1910
1912
1909
1915
14.68
14.62
14.69
14.68
14.79
14.74
14.77
14.72
14.82
14.72
6
Me
H
Me
H
2.90 (137)
1.59 (137)
1.62 (123)
1.72 (135)
1.77 (128)
1.78 (136)
1.76 (129)
1.91 (136)
7
SiMe3
8
SiMe3
Me
H
Me
H
9
SiMe2Ph
SiMe2Ph
SiMe3
10
11
12
13
14
Me
H
Me
CF3
CF3
CF3
CF3
SiMe3
Me
H
SiMe2Ph
SiMe2Ph
Me
1.97 (131)
1909
a
b
c
NMR spectra recorded in CD2Cl2 for compounds 5−10 inclusive; CDCl3 for 11−14. Referenced to 85% H3PO4. Referenced to SiMe4.
d
e
1
Measured using coupled H−13C HSQC spectra. Recorded as solutions in CH2Cl2.
“alkene-like” character than for the silyl derivatives; however,
spectroscopic data (Table 3) in each case reflect the anticipated
3 3
1
the magnitude of JCH in 6 (137 Hz) is comparable, while a
trend in δP for the Palkene center (pz* < pz < pzMe,CF < pzCF ),
the more electron-withdrawing CF3 moiety imparting appreci-
able deshielding. It is noteworthy that in each of 11−14 a single
positional isomer is apparently formed with respect to the
pyrazolyl substituents, the assignment of which is nontrivial in
lieu of structural data. However, while the CF3 moieties exhibit
correlation to both Palkene and one of the PPh3 ligands, only for
the former is an appreciable coupling observed (4JPF ≈ 20 Hz),
consistent with CF3 being proximal to the Palkene center. This
can be rationalized in terms of the steric demand of
accommodating the bulkier CF3 (cf. Me) between flanking
1
slightly greater variation in JPC coupling (67 Hz, 5; 69 Hz, 6)
over the alkenyl (1JPC ≈ 59 Hz, 1)13 may reflect a marginal
increase in s-character. Finally, infrared spectroscopic data for
5−10 indicate a significant reduction in the carbonyl stretching
frequencies in comparison to the parent phosphaalkenyls.
Indeed, while νCO for the latter are entirely consistent with
Ru(II) (vide supra; 1929 cm−1 for 1), those of 5−10 are more
akin to the limited range of Ru(0) monocarbonyls reported to
date (1910−1880 cm−1),30 while the force constants for the
CO bond are consistent with those derived from Ru(0)
dicarbonyls.31
PPh3 units. Indeed, reacting 2 or 3 with Lipz(CF ) , for which
this is unavoidable, fails to afford the fluorinated analogues of 8
and 10, resulting instead in degradation of the ruthenaphospha-
3
2
Taken together, these data suggest that compounds 5−10 are
perhaps best described using the Dewar−Chatt−Duncanson
2
alkenyls; comparable results are noted with Lipz(tBu) , thus
2
model, and formulated as η -phosphaalkene complexes. Thus,
dπ→π*(PC) retro-donation can be considered a dominant
contribution to metal−ligand binding (albeit potentially
diminished in complexes 5 and 6, a corollary of reduced
acceptor character of tert-butyl compared with silyl), as was
negating the possibility of an electronic effect associated with
the bis-trifluoromethyl system.
DFT Studies. The optimized ground-state geometries of 5
and 7 (Figure 6) both show good agreement with the solid-
described by Cowley for [Ni{η2-(Me3Si) CPCH(SiMe3)2}-
2
(PMe3)] (dPC = 1.773(8) Å),32 which also exhibited a
significantly low-frequency resonance for Palkene (δP = 23).
More recently, Ionkin described a similar situation (δP = 54) for
his chelated phosphaalkene complex (Chart 3),33 the significant
Chart 3. A Chelated Ruthenium η2-Phosphaalkene Complex
Figure 6. Optimized geometries of 5 (left) and 7 (right), with
hydrogen atoms and phenyl rings omitted for clarity.
state data for the latter.20 There is only marginal variation in
geometry about the P−CH moiety, 5 exhibiting a slightly wider
P−C−R angle (119.24°, cf. 117.23° in 7) and increased
displacement of carbon from the metal center (2.244 Å, cf.
2.240 Å in 7), while other parameters are comparable. This
would seem to exclude significant variation in the extent of
“alkene” character being responsible for the observed
shift from the free ligand (δP = 248), which was mirrored in the
13C data (δC = 67, cf. 181 for the free ligand), being deemed
consistent with an η2-coordination mode. These data fit well
with the trends noted herein.
t
spectroscopic variations between silyl and Bu systems. Indeed,
A further notable feature in the spectroscopic data of 5−10 is
the appreciable shielding of the Palkene center in the 1,3-
dimethylpyrazole derivatives, compared with their pyrazole
analogues, presumably reflecting the enhanced donor strength
of pz* over pz. This was verified by preparing the analogues
though the calculated isotropic shielding tensors for 5 and 7
(31P, 13C, and 1H, see Table 4) are in less close agreement than
for their parent phopshaalkenyls (vide supra), they do mirror
the experimental trend. Thus, for the “P−CH” fragment, the
phosphorus center of 5 resonates at somewhat lower frequency
than that of 7 (ΔδP = −13.6, cf. −19.9 expt), while significant
11−14, which incorporate pzCF and pzMe,CF moieties.34 The
3
3
E
DOI: 10.1021/om5012177
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Table 4. Calculated Spectroscopic Data for 5 and 7
CONCLUDING REMARKS
■
ab
,
ab
,
We have described the synthesis of several ruthenaphospha-
alkenyl complexes by the hydroruthenation of the silylphospha-
alkynes RMe2SiCP (R = Me, Ph, p-Tol), and provided the
first structural (X-ray and DFT) characterization of these
intriguing compounds. The complexes are thus confirmed to
adopt square-pyramidal geometry about ruthenium and
comprise a formal one-electron phosphaalkenyl ligand, as was
previously inferred for [Ru{PCH(tBu)}Cl(CO)(PPh3)2] on
the basis of reactivity studies. While that latter remains elusive
to crystallographic study, DFT has provided adequate evidence
to confirm a comparable geometry to its silyl counterparts.
All of the complexes are found to react with lithium
pyrazolates, seemingly resulting in reduction of both the metal
(Ru(II)→Ru(0)) and phosphaalkenyl moiety. The resulting
complexes exhibit a metallacyclic core (Ru−P−C) that might
feasibly be described as a ruthenaphosphirane, the Ru−P bond
of which is additionally bridged by the pyrazolyl group.
However, spectroscopic and structural data are inconclusive,
being equally consistent with the η2-coordination of a
phosphaalkene, tethered by the pyrazolyl moiety, with a
dominant bonding contribution from dπ→π*PC retro-
donation. Indeed, on balance, we currently favor this
description, based on the Dewar−Chatt−Duncanson model.
Regardless of the correct formalism, the process by which these
novel complexes are obtained is equally intriguing and remains
to be firmly established. While it is not currently possible to
fully discount the direct nucleophilic attack at phosphorus
which would imply true ambiphilic character for the phospha-
alkenyl ligand, for which some support is foundevidence
would seem to favor initial addition of the pyrazolate to
ruthenium. However, the full mechanistic features of this
reaction remain to be established, and are the subject of
ongoing investigations.
B3LYP
PBEPBE
ac
νCO /cm−1
,
δP
δC
δH
δP
δC
δH
5
7
94.1
96.9
65.3
3.52
2.30
73.3
82.6
100.9
65.8
3.99
2.1
1912.8
1915.9
108.1
a
b
Lanl2dz on Ru; 6-31G** on all other atoms. Data for the P−CH
fragment, calculated using the GIAO method, referenced against
H3PO4 and Me4Si at the same level of theory. B3LYP, frequency
c
scaling factor of 0.961 applied.
deshielding is also apparent for both 13C and 1H nuclei (ΔδC =
31.4, ΔδH = 1.25, cf. 34.0 and 1.22 expt). The calculated
carbonyl stretching frequencies correlate well with the
experimental data, the significant decrease from those of the
parent phosphaalkenyls being consistent with reduction of the
metal (Ru(II)→Ru(0)), as previously inferred (vide supra).
Mechanistic Considerations. The mechanism by which
compounds 5−14 form from the respective phosphaalkenyls
and Lipz′ is the subject of ongoing experimental and
computational studies; however, brief comment is warranted.
Intuitively, one might anticipate nucleophilic attack at the
ruthenium center, given its predominant contribution to the
LUMO and accessibility through the basal plane. Indeed,
complex 1 was shown to readily add donors (CO, CNR) at this
site,15 albeit that an apparently strong trans influence imparted
significant lability. Moreover, the reaction of 1 with the
carboxylate salts Na[O2CR] (R = H, Fc) was shown to afford
[Ru{PCHtBu}(O2CH)(CO)(PPh3)2] via formal nucleo-
philic displacement of chloride,15 presumably via an associative
mechanism. It is also reasonable to consider that in the reaction
of 1 or 2 with electrophilic species such as RHgCl, MeI or
AuCl(L),15,19a,b,e,20 the ensuing 1,2 addition across the Ru−P
bond involves installation of a nucleophilic fragment (X−) at
the vacant metal site, though whether this is concomitant with
addition of the electrophilic fragment to phosphorus, or
facilitated by it, has not been established.
However, one cannot arbitrarily dismiss the possibility of
initial nucleophilic attack at the phosphorus center. While
nucleophilicity at this site is characteristic of one-electron
phosphaalkenyls and has been well established for both 115 and
2,20 NBO analysis (vide supra) has provided evidence of
appreciable δ+ character. Moreover, as noted, the π*(PC)
orbital is a significant component of the LUMO+1 (LUMO+2
in 1), which lies moderately close in energy to the LUMO (ΔE
≈ 0.6 eV), thus offering a viable competitive pathway.
Notwithstanding, in the formation of 11−14, we have inferred
the influence of sterics in directing the bulkier CF3 substituent
EXPERIMENTAL SECTION
■
General Methods. All maniplations were performed under strict
anaerobic conditions using standard Schlenk line and glovebox
(MBraun) techniques, working under an atmosphere of dry argon
or dinitrogen, respectively. Solvents were distilled from appropriate
drying agents and stored over either molecular sieves (4 Å, for DCM
and THF) or potassium mirrors. General reagents were obtained from
Sigma-Aldrich or Fisher and purified by appropriate methods before
use; precious metal salts were obtained from STREM. [RuHCl(CO)-
(PPh3)3],37 tBuCP,38 RMe2SiCH2PCl2 (R = Me, Ph),23 Me3SiC
P,20,39 and [Ru{PCH(tBu)}Cl(CO)(PPh3)2]13,15 were prepared by
literature methods. Unless otherwise stated, NMR spectra were
recorded at 303 K on a Varian VNMRS 400 (1H, 399.50 MHz; 13C,
100.46 MHz; 19F, 375.87; 31P, 161.71 MHz; 29Si, 79.37 MHz);
VNMRS 500 (1H, 499.91 MHz; 13C, 125.72 MHz) or 600 (1H, 599.69
MHz; 13C, 150.81 MHz, 31P, 242.83 MHz) spectrometers were used in
selected instances. All spectra are referenced to external Me4Si, 85%
H3PO4, and CFCl3 as appropriate. Carbon-13 spectra were assigned by
recourse to the 2D (HSQC, HMBC) spectra; phosphaalkenic proton
(cf. H, Me) to orient away from the metal center; we have also
35
noted this in the reaction of 2 with LipztBu
.
While not fully
excluding the possibility of attack at phosphorus,36 this
outcome would necessarily follow from an associative addition
to ruthenium, sterics likely precluding approach of the more
1
1
and silicon shifts were determined indirectly by H−31P and H−29Si
correlation (HMBC). Mass spectrometry was performed by Dr A.
Abdul-Sada of the departmental service. Elemental analyses were
obtained by Mr. S. Boyer of the London Metropolitan University
Elemental Analysis Service.
t
encumbered (α-CF3 or Bu) nitrogen center. Thus, while we
are yet to reach a definitive conclusion, weight of evidence
would currently suggest initial addition to the ruthenium
center, presumably followed by elimination of LiCl. However,
the process by which the putative pyrazolate complexes
[Ru{PCH(R)}(pz′)(CO)(PPh3)2] subsequently convert to
[Ru{η1-N:η2-P,C-P(pz′)CH(SiMe3)}(CO)(PPh3)2] with
concomitant reduction of the metal remains unclear.
X-ray Diffraction Studies. Single-crystal X-ray diffraction data
were recorded on an Agilent Xcalibur Eos Gemini Ultra diffractometer
with CCD plate detector using Mo Kα (λ = 0.71073) or Cu Kα (λ =
1.54184) radiation. Structure solution and refinement were performed
using SHELXS40 and SHELXL,40 respectively, running under
WinGX41 or Olex2.42
F
DOI: 10.1021/om5012177
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
DFT Calculations. Calculations were performed using Gaussian
09W, Revision C.01,43 running on an Intel Core i5-2500 (quad, 3.3
GHz), equipped with 4 GB RAM; results were visualized using
GaussView 5.0. Geometries were optimized with the hybrid density
functional B3LYP, using the RECP basis set Lanl2dz for Ru and 6-
31G** for all other atoms. Minima were characterized by frequency
calculations, and calculated frequencies adjusted by standard scaling
factors. NMR shielding tensors were calculated at the same level of
theory with both the B3LYP and PBEPBE hybrid functionals using the
GIAO method, and compared against those similarly calculated for the
respective reference standards to derive chemical shifts.
(p-Tol)Me2SiCH2Cl. To a cooled (−10 °C ), stirred ethereal
solution (30 cm3) of ClMe2SiCH2Cl (10 cm3, 0.076 mol) was added a
THF solution of p-TolMgBr (57 cm3, 1.33 M, 0.065 mol). After 45
min, the mixture was brought to reflux for 18 h, and then allowed to
cool to ambient temperature with continued stirring. The solvents
were removed by distillation at ambient pressure, and then the residue
was distilled under reduced pressure (2.3 mbar, 55 °C) to afford (p-
Tol)Me2SiCH2Cl as a colorless liquid (6.6 g, 43%), which was
identified on the basis of literature data.44 1H NMR (CDCl3): δ 0.41
(s, 6H, Si(CH3)2), 2.37 (s, 3H, CH3−Ar), 2.94 (s, 2H, CH2Cl), 7.21
(d, J = 7.71 Hz, 2H, Ar−H), 7.45 (d, J = 7.71, 2H, Ar−H). 13C NMR
(CDCl3): δ 4.3 (s, 1JSiC = 54.1 Hz, Si(CH3)2), 21.6 (s Ar−CH3), 30.7
(s, CH2Cl), 128.98 (s, Ar−H), 133.9 (s, Ar−H). 29Si NMR (CDCl3):
δ −4.1.
obtained by storage of a saturated ether solution at 4 °C for several
days.
Crystal data for 2: C41H40ClOP3RuSi·C4H10O, Mw = 954.49,
monoclinic, P21/c (no. 14), a = 9.7961(5), b = 34.2580(17), and c =
14.8457(7) Å, β = 95.201(5)°, V = 4961.6(4) Å3, Z = 4, Dc = 1.278
Mg m−3, μ(Cu Kα) = 4.491 mm−1, T = 173(2) K, 9180 independent
reflections, full-matrix F2 refinement, R1 = 0.0876, wR2 = 0.2864 on
6502 independent absorption-corrected reflections [I > 2σ(I); 2θmax
=
141.8°], 473 parameters, CCDC 1036624.
1
Data for 3. H NMR (CD2Cl2): δH 7.66−7.56 (m, 12 H, Ar),
7.50−7.41 (m, 8 H, Ar), 7.40 (s, 1H, PCH), 7.39−7.29 (m, 12 H,
Ar), 0.26 (s, JSiH 6.3 Hz, 6 H, SiMe2). 13C{1H} NMR (CD2Cl2, 150.81
MHz, 298 K): δC 201.9 (t, JPC 15 Hz, CO), 163.7 (d., JPC = 77 Hz,
CH, PCH), 134.3 (t, JPC 5.5 Hz, CH, PAr), 133.5 (s, CH, Ph), 132.1
(t, JPC 23.2 Hz, C, PAr), 130.3 (s, CH, Ph), 128.5 (s, C, Ph), 128.2 (t,
JPC 5.2 Hz, CH, PAr), 127.5 (s, CH, Ph), −1.3 (d, JCP 7.7 Hz,
Si(CH3)2). 31P{1H} NMR (CD2Cl2): δP 553.8 (t, JPP 8 Hz), 33.7 (d,
JPP 8 Hz). 29Si{1H} NMR (C6D6): δSi −14.3. νCO = 1938 cm−1. Anal.
Found: C, 63.53; H, 4.75. Calcd for C44H42ClOP3RuSi: C, 63.63; H,
4.88. X-ray-quality crystals were obtained by slow evaporation of a
saturated CH2Cl2/hexane solution at ambient temperature.
Crystal data for 3: C44H42ClOP3RuSi, Mw = 868.37, monoclinic,
P21/c (no. 14), a = 19.6355(5), b = 11.9196(2), and c = 19.5933(5) Å,
β = 116.565(3)°, V = 4101.6(2) Å3, Z = 4, Dc = 1.406 Mg m−3, μ(Cu
Kα) = 5.346 mm−1, T = 173(2) K, 7897 independent reflections, full-
matrix F2 refinement, R1 = 0.0267, wR2 = 0.0714 on 7237 independent
absorption-corrected reflections [I > 2σ(I); 2θmax = 143.6°], 479
parameters, CCDC 1036625.
(p-Tol)Me2SiCH2PCl2. Following from literature methods for
related compounds,23 TolMe2SiCH2Cl (6.6 g, 0.033 mol) in ether
(15 cm3) was added, dropwise, to a stirring suspension of activated Mg
(2.0 g, 0.08 mol) in ether (20 cm3), at a rate to maintain reflux. Stirring
was continued while the reaction cooled to ambient temperature, and
then for a further 2 h. The mixture was then filtered directly into an
ethereal solution (20 cm3) of PCl3 (4.5 cm3, 0.05 mol) held at −78 °C
. The mixture was then stirred for 30 min at this temperature, before
being allowed to warm to ambient temperature over the course of 18
h. The solution was filtered, and the residues were washed with Et2O
(3 × 15 cm3); the combined filtrate was stripped of Et2O by
distillation at ambient temperature to afford a colorless liquid (5.92 g,
Data for 4. Yield: 59%. 1H NMR (CD2Cl2, 499.9 MHz): δH 0.20 (s,
6H, Si(CH3)2), 2.31 (s, 3H, CH3), 6.9−7.46, 7.55−7.61 (2m, 30H
PAr3, 4H C6H4, 1H PC). 13C{1H} NMR (CD2Cl2): δC 1.4 (s,
Si(CH3)2), 21.7 (s, Ar−CH3), 127.3 (dd, J = 7 Hz, 9 Hz, P−Ar),
128.0, (t, J = 5 Hz), 128.8 (t, J = 5 Hz), 130.1 (ipso-CH), 129.8 (P−
Ar), 129.5 (P−Ar), 130.9 (P−Ar), 132.8 (t, J = 23 Hz, PAr), 134.3 (o-
CH), 135.0 (m, PAr), 135.7 (m, P−Ar), 136.5 (t, J = 23 Hz, P−Ar),
138.28 (para-CH), 165.2 (br, CP), 202.5 (br, CO). 31P{1H} NMR
(CD2Cl2): δP 33.7 (d, JPP = 8 Hz, PPh3), 552.6 (t, JPP = 8 Hz, PC).
29Si{1H} NMR (CD2Cl2): δSi −14.4. νCO = 1936 cm−1. Anal. Found:
C, 64.02; H, 5.14. Calcd for C47H44ClOP3RuSi: C, 63.98; H, 5.03. X-
ray-quality crystals were obtained by slow evaporation of a saturated
CH2Cl2 solution at ambient temperature.
1
2
67%). H NMR (CDCl3): δ 0.48 (s, 6H SiMe2), 2.24 (d, JPH = 15.2
Hz, CH2), 2.37 (s, 3H, Me), 7.22 (d, 3JC−H = 7.4 Hz, Ar−H), 7.44 (d,
3JC−H = 7.4 Hz, Ar−H). 13C{1H} NMR (CDCl3): δ −1.33 (s, SiMe2),
1
21.6 (s, CH3), 35.2 (d, JC−P = 61 Hz, CH2), 129.1 (s, Ar−H), 133.1
Crystal data for 4: C47H44ClOP3RuSi, Mw = 882.34, monoclinic,
P21/c (no. 14), a = 19.6947(6), b = 12.0013(2), and c = 19.7876(5) Å,
β = 116.762(4)°, V = 4176.0(2) Å3, Z = 4, Dc = 1.403 Mg m−3, μ(Cu
Kα) = 5.259 mm−1, T = 173(2) K, 6511 independent reflections, full-
matrix F2 refinement, R1 = 0.0384, wR2 = 0.1118 on 5898 independent
absorption-corrected reflections [I > 2σ(I); 2θmax = 123.6°], 490
parameters, CCDC 1036626.
(d, 3JC−P = 4 Hz, Si−C), 133.7 (Ar−H), 140.0 (s, C−Me). 29Si NMR
(CDCl3): δ −6.7. 31P NMR (CDCl3): δ 203.3.
(p-Tol)Me2SiCP. As previously described for RMe2SiCP (R =
Me, Ph),20,38 TolMe2SiCH2PCl2 (0.595 g, 2.4 mmol) as a solution in
toluene was added to a toluene suspension of AgOTf (1.26 g, 4.9
mmol); after this mixture was stirred for 10 min, DABCO (0.550 g, 4.9
mmol) was added as a solution in toluene. After being stirred for 1 h,
the mixture was filtered and then calibrated for concentration by
integration of its 31P{1H} NMR resonance (δP 103.3) against that of
fully relaxed (d1 = 150 s) PPh3. Samples were stored below 5 °C (<1
week) and recalibrated before use.
[Ru{η1-N:η2-P,C-P(pz)CH(tBu)}(CO)(PPh3)2] (5). At ambient
temperature, to a solution of pzH (0.010 g, 0.150 mmol) in THF
(5 cm3) was added nBuLi (0.06 cm3, 2.5M, 0.150 mmol). The mixture
was stirred for ca. 10 min and then transferred via cannula to a stirred
solution of 1 (0.119 g, 0.150 mmol). After the mixture was stirred for 1
h, the solvent was removed under reduced pressure, and then the
product was extracted into CH2Cl2 (5 cm3), filtered, and taken to
[Ru{PCH(SiMe2R)}Cl(CO)(PPh3)2] (R = Me, 2; Ph, 3; p-Tol, 4).
In a typical reaction, to a stirring suspension of [RuHCl(CO)(PPh3)3]
(1.5 g, 1.53 mmol) in CH2Cl2 (15 cm3) was added an excess (1.3
equiv) of RMe2SiCP as a solution in toluene (ca. 25 cm3). After this
mixture was stirred for 1 h, the solvent was removed under reduced
pressure to afford an orange/brown residue, which was washed
vigorously with n-hexane (3 × 10 cm3). The solvent was then removed
by filtration, to afford a yellow to orange solid, which was dried in
vacuo.
1
dryness in vacuo. Yield: 0.078 g, 63%. H NMR (CD2Cl2): δH 7.36−
7.10 (m, 30 H, P(C6H5)), 6.91 (d, JHH = 2.26 Hz, 1 H, Pz-H3), 5.58
(br, 1 H, Pz-H5), 5.54 (m, 1 H, Pz-H4), 2.84 (m, 1 H, P−CH), 0.88 (s,
9 H, C(CH3)3). 13C{1H} NMR (CD2Cl2): δC 211.7 (m, CO), 140.9
(s, Pz-C3), 135.9 (s, Pz-C5), 138.8−128.2 (m, P(C6H5)), 105.2 (s, Pz-
C4), 81.6 (ddd, JCP = 68.65, 36.36, 4.83 Hz, CHtBu), 37.7 (d, JCP
=
14.83 Hz, C(CH3)3), 33.4 (m, C(CH3)3). 31P{1H} NMR (CD2Cl2): δP
44.2 (dd, JPP = 17.45, 8.10 Hz), 42.5 (dd, JPP = 47.14, 17.42 Hz), 38.8
(dd, JPP = 47.02, 8.17 Hz, PC). νCO = 1906 cm−1. Anal. Found: C,
62.34; H, 5.42; N, 3.58. Calcd for C45H43P3N2ORu·0.75CH2Cl2: C,
62.05; H, 5.07; N, 3.16.45
1
Data for 2. Yield, 95%. H NMR (C6D6, 499.9 MHz): δH 7.92−
7.85 (m, 12 H, PAr3), 7.39 (s, 1H, PCH), 7.08−6.98 (m, 18 H,
PAr3), 0.18 (s, JSiH 6.5 Hz, 9 H). 13C{1H} NMR (C6D6) δC 203.0 (m,
CO), 168.0 (br, CH, PCH), 134.1, 132.2, 127.6 (m, CH, PAr3 x
3), 0.9 (d, JCP 6.4 Hz, Si(CH3)3). 31P{1H} NMR (C6D6): δP 34.6 (d,
[Ru{η1-N:η2-P,C-P(pz*)CH(tBu)}(CO)(PPh3)2] (6). Prepared as
JPP 8 Hz), 548.5 (t, JPP 8 Hz). 29Si{1H} NMR (C6D6): δSi −9.4. νCO
=
n
for 5, commencing with pz*H (0.155 g, 0.160 mmol), BuLi (0.07
1920 cm−1. Anal. Found: C, 60.91; H, 4.82. Calcd for
C41H40ClOP3RuSi: C, 61.07; H, 5.00. X-ray-quality crystals were
cm3, 2.5 M, 0.160 mmol), and 1 (0.126 g, 0.160 mmol). Yield: 0.090 g,
66%. 1H NMR (CD2Cl2): δH 7.39−7.13 (m, 30 H, P(C6H5)), 5.14 (s,
G
DOI: 10.1021/om5012177
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
1 H, Pz*-H4), 2.90 (ddd, JHP = 5.70, 3.28, 2.38 Hz, 1JCH = 137 Hz, 1 H,
P−CH), 1.96 (s, 3 H, Pz*-CH3-5), 0.91 (s, 9 H, C(CH3)3), 0.43 (s, 3
H, Pz*-CH3-3). 13C{1H} NMR (CD2Cl2): δC 211.8 (m, CO), 152.4
(s, Pz*-C3), 145.6 (d, JCP = 1.63 Hz, Pz*-C5), 134.7−134.2 (m,
P(C6H5)), 129.5−128.0 (m, P(C6H5)), 105.6 (s, Pz*-C4), 79.8 (ddd,
JCP = 66.67, 36.99, 5.43 Hz, CHtBu), 37.7 (d, JCP = 13.72 Hz,
C(CH3)3), 34.0 (dd, JCP = 9.47, 3.67 Hz, C(CH3)3), 12.1 (s, Pz*-CH3-
3), 9.6 (d, JCP = 5.26 Hz, Pz*-CH3-5). 31P{1H} NMR (CD2Cl2): δP
45.5 (dd, JPP = 17.28, 8.64 Hz), 41.4 (dd, JPP = 50.36, 16.98 Hz), 14.7
(dd, JPP = 50.44, 8.56 Hz, PC). νCO = 1906 cm−1. MS [FAB]: m/z
(%) 850 [M+], 751 [M−Pz*]+, 655 [M−Pz*−PC(H)tBu]+. Anal.
Found: C, 62.27; H, 5.41; N, 3.26. Calcd for C47H47N2OP3Ru: C,
66.43; H, 5.57; N, 3.30.
Found: C, 65.87; H, 5.29; N, 3.09. Calcd for C51H49P3N2OSiRu: C,
66.01; H, 5.32; N, 3.02.
[Ru{η1-N:η2-P,C-P(pz′)CH(SiMe3)}(CO)(PPh3)2] (pz′ = pzH,CF
,
3
11; pzMe,CF , 12). Prepared in an analogous fashion to 7 and 8, by
lithiation of the respective pz′H, and subsequent addition to 1 equiv of
2 as a solution in THF.
3
Data for 11. 1H NMR (CDCl3): δH 7.39−7.16 (br m, 24 H, C6H5),
7.07 (br m, 6 H, C6H5), 5.59 (s, 1 H, PzCF -H ), 5.28 (s, 1 H, Pz
-
4
CF3
3
H3), 1.78 (br s, 1 H, CHSi), −0.17 (s, 9 H, Si(CH3)3). 13C{1H}
(CDCl3): δC 190.0 (CO), 137.3 (m, C, PC6H5 ipso), 135.9 (s, PzCF
-
3
C5), 133.6 (m, CH, PC6H5), 128.6 (obscured q, JCF = 248 Hz, CF3),
127.9 (m CH, PC6H5), 0.98 (s, SiCH3), remaining resonances not
4
resolved. 31P{1H} NMR (CDCl3): δP 76.6 (dq, JPP = 43.68 Hz, JPF
=
[Ru{η1-N:η2-P,C-P(pz)CH(SiMe3)}(CO)(PPh3)2] (7). Prepared as
for 5 from pzH (0.010 g, 0.150 mmol), nBuLi (0.06 cm3, 0.150 mmol)
and 2 (0.121 g, 0.150 mmol). Yield: 0.090 g, 72%. 31P{1H} NMR
(CD2Cl2, 161.7 MHz): δP 58.7 (d, JPP = 47 Hz), 46.6 (d, JPP = 18 Hz),
18.40 Hz, PC), 47.7 (d, JPP = 18.13 Hz), 41.5 (dd, JPP = 43.85, 17.99
Hz). 29Si{1H} NMR (CDCl3): δSi −1.1. 19F NMR (CDCl3): δF −60.1
4
(d, JFP = 18.07 Hz). νCO = 1912 cm−1. Anal. Found: C, 59.60; H,
4.52; N, 3.15. Calcd for C45H42P3F3N2OSiRu: C, 59.67; H, 4.64; N,
3.09.
1
42.0 (dd, JPP = 47, 18 Hz). H NMR (CD2Cl2): δH 7.38−7.30, 7.27−
Data for 12. 1H NMR (CDCl3): δH 7.45−7.41 (br m, 6 H, C6H5),
7.17, 7.12−7.06 (3m, 30 H, PAr3), 6.89 (br 1 H, pz-H3), 5.48 (br, 1 H,
pz-H5), 5.45 (br, 1 H, pz-H4), 1.59 (br, 1 H, P-CH), 0.18 (s, 9 H,
Si(CH3)3). 13C{1H} NMR (CD2Cl2): δC 211.2 (m, CO), 141.3 (pz-
C3), 135.7 (pz-C4), 138.2 (m, ipso-PAr3), 134.3, 129.0, 128.3 (3 × CH,
PAr3), 105.0 (pz-C5), 47.6 (ddd, JCP = 79, 31, 4 Hz, P−CH(SiMe3)),
1.6 (dm, JCP = 5 Hz, Si(CH3)3). 29Si{1H} NMR (CD2Cl2): δSi −1.38.
νCO = 1906 cm−1. Anal. Found: C, 62.95; H, 5.15; N, 3.30. Calcd for
C44H43P3N2OSiRu: C, 63.08; H, 5.13; N, 3.34.
7.27−7.20 (br m, 18 H, C61H5), 7.16−7.12 (br m, 6 H, C6H5), 5.52 (s,
4
1 H, PzMe,CF -H ), 1.76 (s, JCH = 129.3 Hz, 1 H, CHSi), 0.55 (s, 3 H,
3
CH3), −0.13 (s, 9 H, Si(CH3)3). 13C{1H} NMR (CDCl3): δC 209.2
3
(br m, CO), 152.5 (br m, PzMe,CF -C ), 137.8 (dd, J = 30.98, 1.60
3
5
Hz, PzMe,CF -C ), 134.3−133.6 (m, C6H5), 129.2−128.6 (m, C6H5),
3
128.0−127.7 (m, C6H5), 119.2 (q, JCF = 268 Hz, CF3), 105.6 (br m,
4
PzMe,CF -C ), 45.2 (ddd, JCP = 80.06, 31.84, 4.63 Hz, SiCH), 11.8 (s,
3
PzMe,CF -CH3-3), 1.7 (dd, JCP = 5.83, 1.40 Hz, Si(CH3)3). 31P{1H}
[Ru{η1-N:η2-P,C-P(pz*)CH(SiMe3)}(CO)(PPh3)2] (8). Prepared
3
NMR (CDCl3): δP 64.6 (dq, JPP = 46.79 Hz, 4JPF = 20.19 Hz, PC),
n
as for 6 from pz*H (0.013 g, 0.135 mmol), BuLi (0.05 cm3, 0.125
46.9 (dd, JPP = 16.85, 1.09 Hz), 38.4 (ddq, JPP = 46.79, 16.86 Hz, 6JPF
=
mmol), and 2 (0.105 g, 0.120 mmol). Yield: 0.080 g, 77%. 13C{1H}
NMR (CD2Cl2, 100.5 MHz): δC 210.4 (m, CO), 152.9 (pz*-C3),
145.7 (d, JCP = 1.4 Hz, pz*-C5), 138.7 (C, ipso-PAr3), 135.7, 129.5,
128.2 (3 × CH, PAr3), 105.5 (d, JCP = 2.7 Hz, pz*-C4), 44.9 (ddd, JCP
= 78, 32, 5 Hz, P−CH(SiMe3)), 12.2 (s, pz*-CH3-3), 9.7 (s, pz*-CH3-
5) 2.2 (dm, JCP = 6 Hz, Si(CH3)3). 31P{1H} NMR (CD2Cl2): δP 46.6
(d, JPP = 17 Hz), 39.3 (dd, JPP = 50, 17 Hz), 32.9 (d, JPP = 47 Hz). 1H
NMR (CD2Cl2): δH 7.58−7.53, 7.38−7.23, 7.21−7.13 (3m, 30 H,
PAr3), 5.12 (br, 1 H, pz-H4), 1.62 (br, 1 H, P−CH), −0.13 (s, 9 H,
Si(CH3)3). 29Si{1H} NMR (CD2Cl2): δSi 1.28. νCO = 1907 cm−1. Anal.
Found: C, 63.35; H, 5.44; N, 3.32. Calcd for C46H47P3N2OSiRu: C,
63.52; H, 5.41; N, 3.22.
1.79 Hz). 29Si{1H} NMR (CDCl3): δSi 2.2. 19F NMR (CDCl3): δF
−60.0 (d, 4JFP = 20.13 Hz). νCO = 1909 cm−1. Anal. Found: C, 59.90;
H, 4.72; N, 2.98. Calcd C46H44F3P3N2OSiRu: C, 60.07; H, 4.82; N,
3.04.
Ru{η1-N:η2-P,C-P(pz′)CH(SiMe2Ph)}(CO)(PPh3)2] (pz′ =
Me,CF3
pzH,CF , 13; pz
, 14). Prepared in an analogous fashion to 7
3
and 8, by lithiation of the respective pz′H, and subsequent addition of
1 equiv of 2 as a solution in THF. Compound 14 forms alongside
decomposition products, limited purification being achieved by
extraction into hexane.34 This compound is characterized spectro-
scopically in situ.
1
[Ru{η1-N:η2-P,C-P(pz)CH(SiMe2Ph)}(CO)(PPh3)2] (9). Pre-
Data for 13. H NMR (CDCl3): δH 7.61 (br m, 2 H, Si(C6H5)),
n
pared as for 5 from pzH (0.020 g, 0.299 mmol), BuLi (0.12 cm3,
7.41−7.18 (br m, 27 H, C6H5), 7.08 (br m, 6 H, C6H5), 5.61 (s, 1 H,
4
CF3
3
PzCF -H ), 5.36 (s, 1 H, Pz -H ), 1.97 (br m, 1 H, CHSi), 0.18 (s, 3
1
3
0.300 mmol), and 3 (0.260 g, 0.299 mmol). Yield: 0.137 g, 51%. H
H, Si(CH3)), −0.03 (s, 3 H, Si(CH3)). 13C{1H} NMR (CDCl3): δC
NMR (CD2Cl2): δH 7.47−7.07 (m, 35 H, P(C6H5) + Ph), 5.46 (br, 1
H, Pz-H4), 7.52 (d, JHH = 2.08 Hz, 1 H, Pz-CH5), 6.81 (d, JHH = 2.08
Hz, 1 H, Pz-CH3), 1.72 (m, 1JCH = 149 Hz, 1 H, CHSi), 0.13 (s, 3 H,
Si(CH3)2), −0.08 (s, 3 H, Si(CH3)2). 13C{1H} NMR (CD2Cl2): δC
211.1 (br, CO), 141.4 (s, Pz-C3), 135.9 (s, Pz-C5), 135.1−127.8 (m,
P(C6H5)), 106.1 (br, Pz-C4), 45.1 (ddd, JCP = 3.58, 29.40, 79.52 Hz,
CHSi), 0.3 (d, JCP = 4.33 Hz, Si(CH3)2), −1.6 (d, JCP = 10.42 Hz,
Si(CH3)2). 31P{1H} NMR (CD2Cl2): δP 57.0 (d, JPP = 47.05 Hz, P
C), 47.0 (d, JPP = 17.77 Hz), 41.7 (dd, JPP = 46.98, 17.63 Hz). 29Si{1H}
NMR (CD2Cl2): δSi −6.6. νCO = 1913 cm−1. Anal. Found: C, 62.37; H,
5.01; N, 3.49. Calcd for C49H45N2OP3SiRu.0.5CH2Cl2: C, 63.08; H,
4.92; N, 2.97.45
198.1 (br m, CO), 142.3 (br m, PzCF -C ), 135.0−133.6 (m, C6H5),
3
3
129.9−127.3 (m, C6H5), 121.4 (q, JCF 267 Hz, CF3), 103.3 (br m,
4
3
PzCF -C ), 46.7 (br m, SiCH), 0.15 (d, JCP = 5.24 Hz, SiCH3),
3
remaining resonances are not resolved. 31P{1H} NMR (CDCl3): δP
2
4
2
74.9 (dq, JPP = 44.45 Hz, JPF = 17.60 Hz, PCH), 48.0 (d, JPP
=
17.68 Hz), 41.3 (dd, 2JPP = 44.45, 17.68 Hz). 29Si{1H} NMR (CDCl3):
δSi −5.3. 19F NMR (CDCl3): δF −60.1 (d, JFP = 19.48 Hz). νCO
=
4
1909 cm−1. High-res ESI+MS: m/z 968.1426 [M]+ (Err = 2.07 ppm).
Anal. Found: C, 61.86; H, 4.49; N, 3.00. Calcd for
C50H44F3P3N2OSiRu: C, 62.05; H, 4.58; N, 2.89.
Data for 14. 1H NMR (CDCl3): δH 7.42 (br m, 12 H, C6H5), 7.23
(br m, 14 H, C6H5), 7.15 (br m, 9 H, C6H5, PPh3 + Ph), 5.53 (s, 1 H,
[Ru{η1-N:η2-P,C-P(pz*)CH(SiMe2Ph)}(CO)(PPh3)2] (10). Pre-
PzMe,CF -H ), 1.97 (br s, 1 H, JCH = 134.52 Hz, CHSi), 0.56 (s, 3 H,
4
1
n
pared as for 6 from pz*H (0.035 g, 0.368 mmol), BuLi (0.15 cm3,
3
CH3), 0.19 (s, 3 H, Si(CH3)), 0.01 (s, 3 H, Si(CH3)). 13C{1H} NMR
1
0.375 mmol), and 3 (0.318 g, 0.367 mmol). Yield: 0.124 g, 37%. H
(CDCl3): δC 209.0 (br m, CO), 152.6 (br m, PzMe,CF -C ), 143.2 (br
3
3
NMR (CD2Cl2): δH 7.50 (m, 5 H, Ar), 7.36−7.14 (m, 30 H, Ar)
(PPh3 + Ph), 5.12 (s, 1 H, Pz*-H4), 1.98 (br, 3 H, Pz*-CH3-5), 1.77
(br, 1 H, 1JCH = 128.49 Hz, CHSi), 0.43 (br, 3 H, Pz*-CH3-3), 0.17 (s,
3 H, Si(CH3)), −0.02 (s, 3 H, Si(CH3)). 13C{1H} NMR (CD2Cl2): δC
210.1 (m, CO), 153.1 (s, Pz*-C3), 145.7 (d, JCP = 1.69 Hz, Pz*-C5),
136.1−127.9 (m, P(C6H5)), 106.7 (d, JCP = 2.74 Hz, Pz*-C4), 41.8
(ddd, JCP = 78.19, 32.40, 4.35 Hz, CHSi), 12.1 (s, Pz*-CH3-3), 9.7 (d,
JCP = 5.45 Hz, Pz*-CH3-5), 0.5 (d, JCP = 8.78 Hz, Si(CH3)2), −0.4 (d,
m, ipso-C6H5), 134.3−133.6 (m, C6H5), 129.2−128.6 (m, C6H5),
128.0−127.5 (m, C6H5), 137.6 (dd, J = 31.06, 1.36 Hz, PzMe,CF -C ),
5
3
119.4 (q, JCF = 270 Hz, CF3), 105.7 (br m, 1JCH = 129.77 Hz, PzMe,CF
-
-
3
C4), 41.8 (ddd, JCP3 = 80.61, 31.43, 4.93 Hz, SiCH), 11.9 (s, PzMe,CF
3
3
CH3-3), 0.16 (d, JCP = 8.53 Hz, SiCH3), −1.2 (d, JCP = 7.66 Hz,
SiCH3). 31P{1H} NMR (CDCl3): δP 62.7 (dq, JPP = 47.06 Hz, JPF
=
4
2
19.69 Hz, PCH), 47.2 (d, JPP = 16.25 Hz), 38.3 (dd, JPP = 47.03,
16.48 Hz). 29Si{1H} NMR (CDCl3): δSi −6.0. 19F NMR (CDCl3): δF
−59.8 (d, 4JFP = 19.48 Hz). νCO = 1915 cm−1. High-res ESI+MS: m/z
982.1582 [M]+ (Err = 4.57 ppm).
JCP = 7.61 Hz, Si(CH3)2). 31P{1H} NMR (CD2Cl2): δP 47.0 (d, JPP
=
16.46 Hz), 38.9 (dd, JPP = 50.75, 16.67 Hz), 32.3 (d, JPP = 50.21 Hz,
PC). 29Si{1H} NMR (CD2Cl2): δSi −4.9. νCO = 1910 cm−1. Anal.
H
DOI: 10.1021/om5012177
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
M.; Cowley, A. H.; Quashie, S. Organometallics 1986, 5, 593−595.
(c) Niecke, E.; Metternich, H.-J.; Nieger, M.; Gudat, D.; Wenderoth,
P.; Malisch, W.; Hahner, C.; Reich, W. Chem. Ber. 1993, 126, 1299−
1309.
ASSOCIATED CONTENT
* Supporting Information
■
S
Final atomic positions of optimized geometries for compounds
1−5 and 7 in xyz format; frontier orbital plots for 1−4; charge
distribution plots for 1 and 2; and crystallographic data, in CIF
format, for 2 (CCDC 1036624), 3 (CCDC 1036625), and 4
(CCDC 1036626). The Supporting Information is available
free of charge on the ACS Publications website at DOI:
10.1021/om5012177.
(10) (a) Weber, L.; Kaminski, O.; Stammler, H.-G.; Neumann, B.;
Romanenko, V. D. Z. Naturfosch. B 1993, 48, 1784−1794. (b) Weber,
L.; Kleinebekel, S.; Ruhlicke, A.; Stammler, H.-G.; Neumann, B. Eur. J.
̈
Inorg. Chem. 2000, 1185−1191.
(11) (a) Gudat, D.; Meidine, M. F.; Nixon, J. F.; Niecke, E. J. Chem.
Soc., Chem. Commun. 1989, 1206−1208. (b) Gudat, D.; Niecke, E.;
Krebs, B.; Dartmann, M. Chimia 1985, 39, 277−279.
(12) (a) Binger, P.; Biedenbach, B.; Kruger, C.; Regitz, M. Angew.
̈
AUTHOR INFORMATION
Corresponding Author
*E-mail: i.crossley@sussex.ac.uk.
■
Chem., Int. Ed. Engl. 1987, 26, 764−765. (b) Driess, M.; Hu, D.;
Pritzkow, H.; Schaufele, H.; Zenneck, U.; Regitz, M.; Rosch, W. J.
̈
̈
Organomet. Chem. 1987, 334, C35−C38. (c) Binger, P.; Biedenbach,
Author Contributions
B.; Mynott, R.; Kruger, C.; Betz, P.; Regitz, M. Angew. Chem., Int. Ed.
̈
†V.K.G. and N.T. contributed equally to the work.
Engl. 1988, 27, 1157−1158. (d) Binger, P.; Haas, J.; Hermann, A. T.;
Langhauser, F.; Kruger, C. Angew. Chem., Int. Ed. Engl. 1991, 30, 310−
̈
Notes
312. (e) Hitchcock, P.; Jones, C.; Nixon, J. F. Angew. Chem., Int. Ed.
The authors declare no competing financial interest.
Engl. 1994, 33, 463−465. (f) Bohm, D.; Knoch, F.; Kummer, S.;
̈
Schmidt, U.; Zenneck, U. Angew. Chem., Int. Ed. Engl. 1995, 34, 198−
201. (g) Binger, P.; Glaser, G.; Gabor, B.; Mynott, R. Angew. Chem.,
Int. Ed. Engl. 1995, 34, 81−83.
ACKNOWLEDGMENTS
■
We thank the Royal Society, Leverhulme Trust (F/00 230/AL,
studentship to N.T.), and University of Sussex (studentship to
V.K.G.) for financial support. I.R.C. gratefully acknowledges the
award of a Royal Society University Research Fellowship. We
thank Dr. I. J. Day (Sussex) for collection of 13C{31P} NMR
spectra for compound 3, Dr. A. Abdul-Sada (Sussex) for
collection of high-resolution MS data for compounds 12−14,
and Dr. M. P. Coles (Sussex/Wellington) for assistance with
the X-ray structural solution for compound 2.
(13) Bedford, R. B.; Hill, A. F.; Jones, C. Angew. Chem., Int. Ed. Engl.
1996, 35, 547−549.
(14) See: Hill, A. F. In Comprehensive Organometallic Chemistry II;
Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds.; Pergamon: Oxford,
1995; Vol. 7.
(15) Bedford, R. B.; Hill, A. F.; Jones, C.; White, A. J. P.; Williams, D.
J.; Wilton-Ely, J. D. E. T. Organometallics 1998, 17, 4744−4753.
(16) Brym, M.; Jones, C. Dalton Trans. 2003, 3665−3667.
(17) Hill, A. F.; Jones, C.; Wilton-Ely, J. D. E. T. Chem. Commun.
1999, 451−452.
(18) (a) Cowley, A. H.; Norman, N. C.; Quashie, S. J. Am. Chem. Soc.
1984, 106, 5007−5008. (b) Arif, A. M.; Cowley, A. H.; Nunn, C. M.;
Quashie, S.; Norman, N. C.; Orpen, A. G. Organometallics 1989, 8,
1878−1884.
DEDICATION
■
Dedicated to the memory of Prof. Michael F. Lappert, an
inspiring colleague.
(19) (a) Bedford, R. B.; Hibbs, D. E.; Hill, A. F.; Hursthouse, M. B.;
Abdul Malik, K. M.; Jones, C. Chem. Commun. 1996, 1895−1896.
(b) Bedford, R. B.; Hill, A. F.; Jones, C.; White, A. J. P.; Williams, D. J.;
Wilton-Ely, J. D. E. T. Chem. Commun. 1997, 179−180. (c) Hill, A. F.;
Jones, C.; White, A. J. P.; Williams, D. J.; Wilton-Ely, J. D. E. T. Chem.
Commun. 1998, 367−368. (d) Bedford, R. B.; Hill, A. F.; Jones, C.;
White, A. J. P.; Williams, D. J.; Wilton-Ely, J. D. E. T. J. Chem. Soc.,
Dalton Trans. 1997, 139−140. (e) Hill, A. F.; Jones, C.; White, A. J. P.;
Williams, D. J.; Wilton-Ely, J. D. E. T. J. Chem. Soc., Dalton Trans.
1998, 1419−1420.
REFERENCES
■
(1) Dillon, K. B.; Mathey, F.; Nixon, J. F. Phosphorus: The Carbon
Copy; Wiley: Chichester, 1998.
(2) (a) Mathey, F. Angew. Chem., Int. Ed. 2003, 42, 1578−1604.
(b) Nixon, J. F. Coord. Chem. Rev. 1995, 145, 201−258. (c) Nixon, J.
F. Chem. Rev. 1988, 88, 1327−1362.
(3) For reviews, see: (a) Appel, R. In Multiple Bonds and Low
Coordination in Phosphorus Chemistry; Regitz, M., Scherer, O. J., Eds.;
Thieme: Stutgart, 1990. (b) Appel, R.; Knoll, F. Adv. Inorg. Chem.
1989, 33, 259−361. (c) Markovski, L. N.; Romanenko, V. D.
Tetrahedron 1989, 45, 6019−6090. (d) Appel, R.; Knoll, F.; Ruppert, I.
Angew. Chem., Int. Ed. Engl. 1981, 20, 731−744.
(4) Le Floch, P. Coord. Chem. Rev. 2006, 250, 627−681 and
references therein.
(5) For recent reviews, see: (a) Weber, L. Coord. Chem. Rev. 2005,
249, 741−763. (b) Weber, L. Angew. Chem., Int. Ed. Engl. 1996, 35,
271−288.
(6) Weber, L.; Reizig, K.; Boese, R.; Polk, M. Angew. Chem., Int. Ed.
Engl. 1985, 24, 604−605.
(7) Weber, L.; Reizig, K.; Frebel, M.; Boese, R.; Polk, M. J.
Organomet. Chem. 1986, 306, 105−114.
(8) (a) Weber, L.; Reizig, K.; Frebel, M. Chem. Ber. 1986, 119, 1857−
1867. (b) Weber, L.; Bungardt, D.; Reizig, K.; Boese, R. Z. Naturfosch.
B 1986, 41, 1096−1106. (c) Weber, L.; Bungardt, D. J. Organomet.
Chem. 1986, 311, 269−280. (d) Weber, L.; Uthmann, S.; Torwiehe,
B.; Kirchhoff, R.; Boese, R.; Blaser, D. Organometallics 1997, 16,
3188−3193. (e) Weber, L.; Scheffer, M. H.; Beckmann, E.; Stammler,
H.-G.; Neumann, B. Organometallics 1997, 16, 2958−2962.
(9) (a) Gudat, D.; Niecke, E.; Malisch, W.; Hofmockel, U.; Quashie,
S.; Cowley, A. H.; Arif, A. M.; Krebs, B.; Dartmann, M. J. Chem. Soc.,
Chem. Commun. 1985, 1687−1689. (b) Gudat, D.; Niecke, E.; Arif, A.
(20) Trathen, N.; Greenacre, V. K.; Crossley, I. R.; Roe, S. M.
Organometallics 2013, 32, 2501−2504.
(21) While Me3SiCP is already known in the literature,22
PhMe2SiCP and TolMe2SiCP, which are obtained in comparable
fashion,22c,d are described for the first time herein.
(22) (a) Appel, R.; Westerhaus, A. Tetrahedron Lett. 1981, 22, 2159−
2160. (b) Guillemin, J. C.; Janati, T.; Guenot, P.; Savignac, P.; Denis, J.
M. Angew. Chem., Int. Ed. Engl. 1991, 30, 196−198. (c) Mansell, S. M.;
Green, M.; Kilby, R. J.; Murry, M.; Russell, C. A. C. R. Chem. 2010, 13,
1073−1081. (d) Mansell, S. M.; Green, M.; Russell, C. A. Dalton
Trans. 2012, 41, 14360−14368.
(23) Averre, C. E.; Coles, M. P.; Crossley, I. R.; Day, I. J. Dalton
Trans. 2012, 41, 278−284.
(24) Search of CCDC: Allen, F. H. Acta Crystallogr., Sect. B: Struct.
Sci. 2002, 58, 380−388.
(25) Takaoka, A.; Mendiratta, A.; Peters, J. C. Organometallics 2009,
28, 3744−3753.
(26) See, for example: (a) Farmer, J. D.; Man, W. Y.; Fox, M. A.;
Yufit, D. S.; Howard, J. A. K.; Hill, A. F.; Low, P. J. J. Organomet. Chem.
2012, 721−722, 173−185. (b) Alcock, N. W.; Hill, A. F.; Melling, R. P.
Organometallics 1991, 10, 3898−3903.
I
DOI: 10.1021/om5012177
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
(27) Choi, S.-H.; Bytheway, I.; Lin, Z.; Jia, G. Organometallics 1998,
17, 3974−3980.
P.; Dannenberg, J. J.; Dapprich, S.; Daniels, A. D.; Farkas, O.;
Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J. Gaussian 09,
Revision C.01; Gaussian, Inc.: Wallingford, CT, 2010.
(44) Hu, C.; He, J.-G.; O’Brien, D. H.; Irgolic, K. J. J. Organomet.
Chem. 1984, 268, 31−38.
(45) Despite considerable effort, it has proven impossible to fully free
these two materials from CH2Cl2 of crystallization. Approximately
0.5−0.75 molecule is routinely present per molecule of 5 or 9 by NMR
integration (δH 5.34).
(28) Maciel, G. E.; McIver, J. W., Jr.; Ostlund, N. S.; Pople, J. A. J.
Am. Chem. Soc. 1970, 92, 1−11.
(29) Allen, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen,
A. G.; Taylor, R. J. Chem. Soc., Perkin Trans. 2 1987, S1−S19.
(30) See, for example: (a) Bohanna, C.; Esteruelas, M. A.; Lahoz, F.
J.; Onate, E.; Oro, L. A.; Sola, E. Organometallics 1995, 14, 4825−
4831. (b) Bolton, P. D.; Grellier, M.; Vautravers, N.; Vendier, L.; Sabo-
Etienne, S. Organometallics 2008, 27, 5088−5093. (c) Hill, A. F.;
Owen, G. R.; White, A. J. P.; Williams, D. J. Angew. Chem., Int. Ed.
1999, 38, 2759−2761.
(31) See, for instance: (a) Christian, D. F.; Roper, W. R. J. Chem. Soc.,
Chem. Commun. 1971, 1271−1272. (b) Herberhold, M.; Hill, A. F. J.
Organomet. Chem. 1990, 395, 195−206.
(32) Cowley, A. H.; Jones, R. A.; Stewart, C. A.; Stuart, A. L.;
Atwood, J. L.; Hunter, W. E.; Zhang, H. M. J. Am. Chem. Soc. 1983,
105, 3737−3738.
(33) Ionkin, A. S.; Marshall, W. J.; Fish, B. M.; Schiffhauer, M. P.;
Davidson, F.; McEwen, C. N.; Keys, D. E. Organometallics 2007, 26,
5050−5058.
(34) Compound 14 forms alongside decomposition products, as
observed by in situ NMR studies. Separation from other metal-
containing species is effected by dissolution in hexane, pentane, or dry
ethanol; however, appreciable solubility in these solvents, alongside
sensitivity to more “invasive” purification methods, has precluded
separation from free PPh3 and other trace impurities. The parent ion is
apparent from high-resolution mass spectrometry, and the species is
otherwise characterized spectroscopically in situ. Compound 14
exhibits an unequivocally characteristic 31P{1H} NMR spectrum (cf.
compounds 5−13), heteronuclear correlation experiments (31P−1H,
1
13C− H, 29Si−1H HMBC, and 13C−1H HSQC) allowing assignment
1
of the key H and 13C resonances. A single 19F-containing species is
apparent and is thus unequivocally assigned.
(35) Trathen, N. Ph.D. Thesis, University of Sussex, 2014.
(36) In the CF3-substituted pyrazolates, appreciable variation in
nucleophilicity between the two nitrogen centers is probable, such that
−
the more encumbered site would be least reactive; for [pztBu
]
the
situation will be less pronounced, but also reversed. Thus, while for
−
[pztBu
] the same isomer might reasonably result from either steric
shielding of the metal or preferential attack at phosphorus, for the
fluorinated systems attack at phosphorus by the more reactive nitrogen
should place the CF3 moiety distal from phosphorus; sterics would
then preclude coordination to the metal. Notwithstanding, reversible
attack at phosphorus, cannot be discounted, which may allow for
formation of the observed isomer.
(37) Boniface, S. M.; Clark, G. R.; Collins, T. J.; Roper, W. R. J.
Organomet. Chem. 1981, 206, 109−117.
(38) Becker, G.; Gresser, G.; Uhl, W. Z. Naturfosch. B 1981, 36, 16−
19.
(39) Trathen, N.; Leech, M. C.; Crossley, I. R.; Greenacre, V. K.;
Roe, S. M. Dalton Trans. 2014, 43, 9004−9007.
(40) Sheldrick, G. M. Acta Crystallogr., Sect. A 2008, 64, 112−122.
(41) Farrugia, L. J. Appl. Crystallogr. 1999, 32, 837−838.
(42) Dolomanov, O. V.; Bourhis, L. J.; Gildea, R. J.; Howard, J. A. K.;
Puschmann, H. J. Appl. Crystallogr. 2009, 42, 339−341.
(43) Frisch, M. J.; Trucks, G. W.; Schlegel, H B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci,
B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H.
P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada, M.;
Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima,
T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery, J. A., Jr.;
Peralta, J. E.; Ogliaro, F.; Bearpark, M.; Heyd, J.; Brothers, E.; Kudin,
K. N.; Staroverov, V. N.; Keith, T.; Kobayashi, R.; Normand, J.;
Raghavachari, K.; Rendell, A.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.;
Cossi, M.; Rega, N.; Millam, J. M.; Klene, M.; Knox, J. E.; Cross, J. B.;
Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.;
Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.;
Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador,
J
DOI: 10.1021/om5012177
Organometallics XXXX, XXX, XXX−XXX