Mono- and dinuclear rhodium(I) and rhodium(III) complexes with the bulky phosphine 2,6-Me2C6H3CH2 CH2PtBu2, including the first structurally characterized cis-configurated dicarbonyl compou

Article abstract of DOI:10.1021/om034348p

The bulky functionalized phosphine 2,6-Me₂C₆H₃CH₂CH₂ PtBu₂ (3) was prepared in a stepwise fashion from the Grignard reagent 2,6-Me₂C₆H₃CH₂ CH

Full text of DOI:10.1021/om034348p

1140
Organometallics 2004, 23, 1140-1152
Mon o- a n d Din u clea r Rh od iu m (I) a n d Rh od iu m (III)
Com p lexes w ith th e Bu lk y P h osp h in e
2,6-Me2C6H3CH2CH2P tBu 2, In clu d in g th e F ir st
Str u ctu r a lly Ch a r a cter ized Cis-Con figu r a ted Dica r bon yl
Com p ou n d , cis-[Rh Cl(CO)2(P R3)]
Giuseppe Canepa, Carsten D. Brandt, and Helmut Werner*
Institut fu¨r Anorganische Chemie der Universita¨t Wu¨rzburg, Am Hubland,
D-97074 Wu¨rzburg, Germany
Received December 4, 2003
The bulky functionalized phosphine 2,6-Me2C6H3CH2CH2PtBu2 (3) was prepared in a
stepwise fashion from the Grignard reagent 2,6-Me2C6H3CH2CH2MgCl, tBuPCl2, and tBuLi.
Phosphine 3 reacts with the olefin compounds [RhCl(C2H4)2]2 and [RhCl(C8H14)2]2 to give
the substitution products [RhCl(olefin)(3)]2 (8, 9), of which 9 (olefin ) C2H4) has been
characterized crystallographically. While 9 is rather inert toward 3, it reacts with 3 under
a hydrogen atmosphere to give the dihydrido complex [RhH2Cl(3)2] (11) via the dimer [RhH2-
Cl(3)]2 (10) as an intermediate. In the presence of ethene, 11 is reconverted to 9. The reaction
of 8 (olefin ) C8H14) with the phosphonium salt 3‚HCl affords a mixture of [RhHCl2(3)]2
(12) and 3, which upon warming at 60 °C produces [RhHCl2(3)2] (13). The attempted
separation of 12 by column chromatography on Al2O3 led unexpectedly to the formation of
the novel half-sandwich-type compound [(η6-2,6-Me2C6H3CH2CH2PtBu2-κP)RhCl] (14). Treat-
ment of either 8 or 14 with CO gives cis-[RhCl(CO)2(3)] (15), which represents the first
structurally characterized dicarbonyl complex with the CO ligands in a cis disposition. In
the absence of carbon monoxide, 15 is rather labile and readily converted to [RhCl(CO)(3)]2
(16). The reaction of 9 with HCl affords the dinuclear ethylrhodium(III) compound 18, being
built up by two 14-electron [RhCl2(C2H5)(3)] units. These units are linked by two bridging
chlorides which are unsymmetrically situated between the two metal centers. Compound
18 reacts with CO to give 15 and with 3 to give 13, presumably in both cases via [RhHCl2-
(C2H4)(3)] as an intermediate. The half-sandwich-type complexes [(η6-2,6-Me2C6H3CH2-
CH2PtBu2-κP)Rh(olefin)]PF6 (20, 21), obtained from [Rh(acetone)2(C8H14)2]PF6 as the
precursor, react in acetone in the presence of H2 to give [RhH2(acetone)3(3)]PF6 (22), which
upon addition of diethyl ether generates the dihydride [(η6-2,6-Me2C6H3CH2CH2PtBu2-κP)-
RhH2]PF6 (23). Compound 23 is a suitable starting material for the preparation of compounds
having the general composition [(η6-2,6-Me2C6H3CH2CH2PtBu2-κP)Rh(L)]PF6, where L is
acetone, CH2dCHR (R ) tBu, Ph), PhCtCH, and CO, respectively.
In tr od u ction
(CH2)2C6H5, for example, the insertion of the metal
occurs exclusively into the phenyl C-H bond situated
in a position ortho to the CH2CH2PR2 substituent, we
were interested to find out what the behavior of a
phosphine such as tBu2PCH2CH2C6H3-2,6-Me2 is, which
has the two ring carbon atoms next to the â-phosphi-
noethyl moiety blocked by methyl groups. In this context
it is appropriate to mention the pioneering work by
Milstein et al. illustrating that the pincer-type ligand
C6H-1,3-(CH2PtBu2)2-2,4,6-Me3 reacts even at room
temperature with [MCl(C8H14)2]2 (M ) Rh, Ir) by C-C
bond cleavage to give the methylrhodium(III) and
-iridium(III) derivatives [MCl(CH3)(C6H-2,4-(CH2PtBu2)2-
3,5-Me2-κ3P,C,P)], respectively.4
Recently, we reported the preparation and derivati-
zation of the new phosphines iPr2P(CH2)2C6H5 and
tBu2P(CH2)2C6H5, which are not only sterically demand-
ing but, in contrast to PiPr3 and PtBu3, can behave
either as 2-electron or (2 + 6)-electron ligands.1 More-
over, these phosphines, in the presence of (olefin)-
rhodium(I) or (olefin)iridium(I) compounds, undergo
C-H activation of the six-membered ring to give aryl-
hydridometal(III) complexes, the aryl group being part
of a C,P-bonded chelating system.2,3 Since in the reac-
tions of [RhCl(C8H14)2]2 or [IrCl(C8H14)2]2 with R2P-
(1) Werner, H.; Canepa, G.; Ilg, K.; Wolf, J . Organometallics 2000,
19, 4756-4766.
(2) (a) Canepa, G.; Brandt, C. D.; Werner, H. Organometallics 2001,
20, 604-606. (b) Canepa, G.; Brandt, C. D.; Ilg, K.; Wolf, J .; Werner,
H. Chem. Eur. J . 2003, 9, 2502-2515.
(4) (a) Rybtchinski, B.; Vigalok, A.; Ben-David, Y.; Milstein, D. J .
Am. Chem. Soc. 1996, 118, 12406-12415. (b) Gandelman, M.; Vigalok,
A.; Shimon, L. J . W.; Milstein, D. Organometallics 1997, 16, 3981-
3986. (c) Rybtchinski, B.; Milstein, D. Angew. Chem. 1999, 111, 918-
932; Angew. Chem., Int. Ed. 1999, 38, 870-883.
(3) Canepa, G.; Sola, E.; Martin, M.; Lahoz, F. J .; Oro, L. A.; Werner,
H. Organometallics 2003, 22, 2151-2160.
10.1021/om034348p CCC: $27.50 © 2004 American Chemical Society
Publication on Web 02/04/2004

Rh(I) and Rh(III) Complexes with a Bulky Phosphine
Organometallics, Vol. 23, No. 5, 2004 1141
Sch em e 1
Sch em e 2a
a
L ) 2,6-Me2C6H3CH2CH2PtBu2.
The present paper describes the synthesis and ligand
behavior of the title phosphine, the isolation of the first
structurally characterized cis-configurated dicarbonyl-
rhodium(I) complex, cis-[RhCl(CO)2(PR3)], the genera-
tion and crystallographic identification of an unusual
dinuclear alkylrhodium(III) compound, and the prepa-
ration of a series of half-sandwich-type complexes in
which the functionalized phosphine coordinates to rhod-
ium(I) or rhodium(III) in a chelating fashion. Some
preliminary results of this work have already been
communicated.5
2, which after fractional distillation at 0.002 bar was
isolated as a colorless air- and moisture-sensitive solid
melting at around room temperature. Subsequent treat-
ment of 2 with a solution of tBuLi in pentane afforded,
after hydrolysis and workup by extraction and fractional
distillation, the required phosphine 3 as an oily liquid
in about 80% yield. Since no correct elemental analysis
of 3 could be obtained, due to the extreme sensitivity
toward air, 3 was characterized by MS and NMR spectra
as well as by derivatization to the corresponding phos-
phonium salts 4 and 5. The 31P NMR spectra of 4 and
5 display in each case a singlet resonance at around δ
49.0, which is shifted downfield by ca. 17 ppm compared
with the neutral phosphine 3.
Resu lts a n d Discu ssion
P r ep a r a tion a n d Der iva tiza tion of th e Title
P h osp h in e 3. One of the well-known procedures for the
preparation of alkyldiphenylphosphines Ph2P(CH2)nC6H5
(n ) 2, 3) consists of the reaction of LiPPh2 or KPPh2
with the respective benzene derivative C6H5(CH2)nX (X
) Cl, Br), which in most cases affords the required
phosphine in good to excellent yields.6 This procedure,
however, could not be applied to di-tert-butylphosphine
analogues such as 3, since dialkyl phosphides MPR2
upon treatment with alkyl halides R′X undergo a
halide-metal exchange which gives via reaction of
MPR2 with the intermediately formed R2PX the corre-
sponding diphosphines.7 Attempts to prepare 3 by
hydrophosphination of CH2dCHC6H3-2,6-Me2 with HPt-
Bu2 in the presence of AIBN (azaisobutyronitrile) as a
radical starter afforded a mixture of products which
contained the title phosphine in about 10-15% yield but
could not be separated by common techniques.
Rea ction s of P h osp h in e 3 w ith [Rh Cl(olefin )2]2.
In contrast to related trialkylphosphines such as tBu2-
PCH3,8 the title compound 3 does not react with [RhCl-
(olefin)2]2 (olefin ) C2H4, C8H14) to give the mononuclear
olefinrhodium(I) complex trans-[RhCl(olefin)(3)2]. With
6 and 7 as the starting materials and a 2-fold excess of
3, the dinuclear compounds 8 and 9 are formed instead
(Scheme 2). Both 8 and 9 are yellow, moderately air-
sensitive solids, which differ quite significantly in their
solubility in organic solvents. While 8 is readily soluble
in benzene and dichloromethane (but less so in diethyl
ether), the solubility of 9, even in CD2Cl2, is rather
scarce. Despite this limitation, the 31P NMR spectrum
of 9 could be measured, which, owing to the appearance
of one doublet at δ 67.0, indicated that probably only
one species is present. In contrast, the 31P NMR
spectrum of 8 displayed two resonances (equally dou-
blets) at δ 64.8 and 65.5, of which that at slightly higher
field dominates and is thus tentatively assigned to the
supposedly thermodynamically preferred trans isomer.
The 31P-103Rh coupling constants of both signals are
nearly the same (188.2 and 185.7 Hz) and are in good
agreement with the value for [RhCl(C8H14)(PiPr3)]2 of
1J (Rh,P) ) 183.2 Hz.9
The successful route to obtain phosphine 3 is outlined
in Scheme 1. The first step consists of the formation of
the Grignard reagent ClMgCH2CH2C6H3-2,6-Me2, which
is generated by addition of a solution of 1 in THF to a
suspension of finely divided Mg in the same solvent.
This Grignard reagent reacted at 0 °C with tBuPCl2 in
THF to give in addition to MgCl2 the chlorophosphine
To find out whether the single species observed in the
31P NMR spectrum of 9 is the cis or the trans isomer of
the dinuclear complex, an X-ray crystal structure analy-
sis was carried out. As shown in Figure 1, the two
(5) Canepa, G.; Brandt, C. D.; Werner, H. J . Am. Chem. Soc. 2002,
124, 9666-9667.
(6) (a) Singewald, E. T.; Shi, X.; Mirkin, C. A.; Schofer, S. J .; Stern,
C. L. Organometallics 1996, 15, 3062-3069. (b) Slone, C. S.; Mirkin,
C. A.; Yap, G. P. A.; Guzei, I. A.; Rheingold, A. L. J . Am. Chem. Soc.
1997, 119, 10743-10753. (c) J an, D.; Delaude, L.; Simal, F.; Demon-
ceau, A.; Noels, A. F. J . Organomet. Chem. 2000, 606, 55-64.
(7) Issleib, K.; Mu¨ller, D.-W. Chem. Ber. 1959, 92, 3175-3182.
(8) Kukla, F.; Werner, H. Inorg. Chim. Acta 1995, 235, 253-161.
(9) Werner, H.; Scha¨fer, M.; Nu¨rnberg, O.; Wolf, J . Chem. Ber. 1994,
127, 27-38.

1142 Organometallics, Vol. 23, No. 5, 2004
Canepa et al.
signal at δ -23.03 (split into a doublet of triplets due
to 1H-103Rh and 1H-31P coupling) and the Rh-H
stretching mode at 2122 cm-1 in the IR spectrum. The
31P NMR spectrum of 11 displays a doublet resonance,
indicating that the two phosphine ligands are stere-
ochemically equivalent.
Regarding the mechanism of formation of 11, we
conclude from the inert behavior of 9 toward phosphine
3 that in the initial step an oxidative addition of H2
followed by the elimination of ethane takes place. This
is supported by the observation that upon stirring a
solution of 9, in the absence of 3, under a H2 atmosphere
a hydridorhodium(III) compound can be detected which
presumably is the dimer 10 (see Scheme 2). Since this
species is only stable in the presence of excess hydrogen,
it has been characterized by spectroscopic techniques.
F igu r e 1. Molecular diagram of compound 9. Selected
bond distances (Å) and angles (deg): Rh(1)-C(1) ) 2.107-
(6), Rh(1)-C(2) ) 2.106(5), Rh(1)-P(1) ) 2.2653(16), Rh-
(1)-Cl(1) ) 2.4077(16), Rh(1)-Cl(2) ) 2.4293(15), Rh(2)-
C(3) ) 2.105(5), Rh(2)-C(4) ) 2.104(5), Rh(2)-P(2) )
2.2701(16), Rh(2)-Cl(1) ) 2.4310(16), Rh(2)-Cl(2) ) 2.4078-
(16); Cl(1)-Rh(1)-Cl(2) ) 80.01(6), Cl(1)-Rh(2)-Cl(2) )
79.98(6), Cl(1)-Rh(1)-P(1) ) 96.99(6), Cl(2)-Rh(1)-P(1)
) 176.70(4), Cl(1)-Rh(2)-P(2) ) 176.75(5), Cl(2)-Rh(2)-
P(2) ) 97.10(6).
1
The H NMR spectrum of 10 shows a hydride signal at
δ -21.50, which like the single 31P NMR resonance at
δ 96.4 is somewhat broadened at 295 K. After the
1
temperature is increased to 313 K, the H NMR spec-
trum displays a sharp doublet at δ -21.48, the chemical
shift being in agreement with the assumption that the
hydrido ligands occupy terminal but not bridging posi-
tions. This proposal is supported by the IR spectrum,
which shows two ν(RhH) vibrations at 2149 and 2125
cm-1: i.e., in a region where the stretching modes of
terminal Rh-H bonds appear.15 To explain the broad-
ening of the NMR resonances at 295 K, it is conceivable
that an equilibrium between a [(PR3)H2Rh(µ-Cl)2RhH2-
(PR3)] dimer and a corresponding isomer with one or
two bridging hydrides exists which at higher tempera-
tures is shifted to the aforementioned molecule. Addition
of 3 to the CH2Cl2 solution of 10 yields exclusively the
monomeric dihydrido complex 11.
ethene and the two phosphine ligands are disposed
trans to each other, as has also been found in [RhCl-
(CO)(PMePh2)]2.10 The C2H4 units are symmetrically
linked to the metal centers and lie nearly perpendicular
to the coordination planes around Rh(1) and Rh(2). The
central Rh2Cl2 four-membered ring is bent, the dihedral
angle between the two planes [RhCl2(C2H4)(3)] being
143.3°. A similar bending of about the same size has
been observed for [RhCl(CO)(PMe2Ph)]2 and for com-
pounds of the general formula [RhCl(L)2]2 with L )
Compound 11 is completely inert toward cyclooctene
and 3,3-dimethyl-1-butene and does not afford [RhCl-
(3)2]n (n ) 1, 2) by abstraction of H2. It reacts, however,
in pentane at room temperature with excess ethene to
give the dimeric product 9. Uncoordinated phosphine 3
can also be detected. The reaction is rather slow at 295
K and 1 bar, and thus even after 3 days small amounts
(ca. 10%) of the starting material are still present.
Replacing the ethene by a hydrogen atmosphere recon-
verts the mixture of 9 and 3 to 11.
14
C2H4,11 cyclohexene,12 CO,13 PF3 as well. It should be
mentioned that although only the trans isomer of 9 has
been found in the crystal, we cannot exclude the
possibility that in solution small amounts of the cis
isomer are present. Their identification might be pre-
vented by the unfavorable signal-to-noise ratio as a
result of the low solubility of the product.
In contrast to what we expected, compounds 8 and 9
do not react with an excess of 3 at room temperature to
afford either trans-[RhCl(olefin)(3)2] or [RhCl(3)2]2. When
the starting materials are heated in benzene at ca. 75
°C, a complicated mixture of products is formed, among
which the half-sandwich-type complex 14 could be
detected. All attempts to separate these mixtures by
column chromatography failed.
The attempted conversion of 9, under a hydrogen
atmosphere in order to eliminate and hydrogenate the
olefin, with 2 equiv of 3 to [RhCl(3)2]n (n ) 1, 2) affords
the dihydrido complex 11 in practically quantitative
yield. Typical features of 11, which is a yellow, moder-
ately air-sensitive solid, are the high-field 1H NMR
An
Un p r eced en t ed
H a lf-Sa n d w ich -Typ e
(Ar en e)r h od iu m (I) Com p lex. While 9 and its cy-
clooctene counterpart 8 are fairly inert toward 3, the
latter reacts with the phosphonium salt 5 in diethyl
ether at room temperature. If the molar ratio of 8 to 5
is 1:2, a mixture of products is isolated which consists
of equal amounts of 5 and a new compound, which we
assume is the dichlorohydridorhodium(III) complex 12
1
(see Scheme 2). The H NMR spectrum of 12 displays a
doublet of doublets resonance at δ -22.48 (for compari-
son see 10: δ -21.48) and the IR spectrum a Rh-H
stretching vibration at 2146 cm-1 (see 10: 2149 and
2125 cm-1). On the basis of the relative intensities of
(10) Bonnet, J . J .; J eannin, Y.; Kalck, P.; Maisonnat, A.; Poilblanc,
R. Inorg. Chem. 1975, 14, 743-747.
1
the H NMR signals, we believe that 12 is an analogue
(11) Klanderman, K. A. Diss. Abstr. 1965, 25, 6253-6254.
(12) Drew, M. G. B.; Nelson, S. M.; Sloan, M. J . Chem. Soc., Dalton
Trans. 1973, 1484-1489.
of 10, with only one hydride and one chloride being
(13) (a) Dahl, L. F.; Martell, C.; Wampler, D. L. J . Am. Chem. Soc.
1961, 83, 1761-1762. (b) Walz, L.; Scheer, P. Acta Crystallogr., Sect.
C 1991, 47, 640-641.
(15) (a) Duckett, S. B.; Haddleton, D. M.; J ackson, S. A.; Perutz,
R. N.; Poliakoff, M.; Upmacis, R. K. Organometallics 1988, 7, 1526-
1532. (b) Bell, T. W.; Haddleton, D. M.; McCamley, A.; Parttridge, M.
G.; Perutz, R. N.; Willner, H. J . Am. Chem. Soc. 1990, 112, 9212-
9226.
(14) Doppelt, P.; Ricard, L.; Weigel, V. Inorg. Chem. 1993, 32, 1039-
1040.

Rh(I) and Rh(III) Complexes with a Bulky Phosphine
Organometallics, Vol. 23, No. 5, 2004 1143
terminally bonded to each rhodium and two chlorides
being in bridging positions. Warming the solution of 5
and 12 in benzene for 2 h at 60 °C leads to the formation
of the monomer 13, which after removal of the solvent
is isolated as an orange air-stable solid in 71% yield.
Typical spectroscopic features of 13 are the high-field
such as Ph2P(CH2)nC6H5 (n ) 2, 3)6,19 and R2P-
(CH2)2C6H5 (R ) iPr, tBu),1,3 that in compound 14 the
chelating phosphine 3 is coordinated as a hemilabile
ligand, we were prompted to find out what the reactivity
of 14 toward carbon monoxide is. Being aware of the
fact that rhodium(I) complexes of the type cis-[RhCl-
(CO)2(PR3)] have been reported by various authors to
be key intermediates in the reactions of [RhCl(CO)2]2
with PR3 and of [RhCl(CO)(PR3)]2 with CO,20 we were
quite optimistic that upon treatment of 14 with carbon
monoxide a dicarbonyl derivative of the required com-
position could be generated.
The reactions of both 14 and dimer 8, the latter
containing a labile cyclooctene ligand, with CO in
pentane or dichloromethane are indeed very fast and
lead in a few seconds to the formation of a yellow
compound, the 31P NMR spectrum of which displays a
single resonance at δ 57.8 (in CD2Cl2). However, after
evaporation of the solvent in vacuo a yellow air-stable
product is isolated which is not the initially formed
species but a mixture of the cis and trans isomers of
the dimer 16. The 31P NMR spectrum of this mixture
shows two resonances (both doublets) at δ 79.4 (1J (Rh,P)
) 172.9 Hz) and 78.6 (1J (Rh,P) ) 174.6 Hz), which are
assigned to cis-[RhCl(CO)(3)]2 and trans-[RhCl(CO)(3)]2,
respectively. Since the cis isomer is more readily soluble
in pentane, it can be washed out and the trans isomer
16 is thus obtained in analytically pure form. The
proposed structure for 16 is supported by the observa-
tion of a doublet of doublets at δ 186.8 for the CO carbon
atoms in the 13C NMR spectrum, the chemical shift and
the 1J (Rh,C) and 2J (P,C) coupling constants being
similar to those of trans-[RhCl(CO)(PPh3)]2.21
1
signal (doublet of triplets) at δ -31.03 in the H NMR
and the doublet resonance at δ 50.0 in the 31P NMR
spectrum, both of which are in support of the proposed
structure.
After we failed to prepare an analogue of either [RhCl-
(PCy3)2]16 or [RhCl(PiPr3)2]217 with the general composi-
tion [RhCl(3)2]n from 8 or 9 and phosphine 3, we
attempted to prepare the required product by treating
the dichloro hydrido complex 13 with NEt3 in benzene.
Although the reaction is quite fast, as indicated by a
quick change of color from orange to light brown and
the precipitation of a white solid ([HNEt3]Cl), the target
compound [RhCl(3)2]n is not formed. Quite surprisingly,
the unusual half-sandwich-type complex 14 is generated
instead. Since 14, similarly to [HNEt3]Cl, is only spar-
ingly soluble in benzene, it could not be completely
separated from the ammonium salt and was thus, in
the initial part of our studies, only characterized by
spectroscopic means.
A clean method to obtain 14 as an analytically pure
compound was found by an unexpected route. While we
attempted to separate the mixture of 5 and 12 using
column chromatography on Al2O3, we observed that
from the yellow material a green fraction could be eluted
with CH2Cl2. Removal of the solvent afforded a green,
very air-sensitive solid which is readily soluble in polar
organic solvents but nearly insoluble in hydrocarbons.
Conductivity measurements confirmed that 14 is a
nonelectrolyte. The coordination of the arene ring to the
metal center is clearly indicated by the 1H and 13C NMR
spectra, in which the signals for the C-H protons and
the ring carbon atoms are shifted considerably to higher
fields compared with those for the free arene. Charac-
teristic in particular is the resonance for the CH carbon
atom in a position para to the CH2CH2PtBu2 substitu-
ent, which appears at δ 94.1 as a doublet of doublets
due to 13C-103Rh and 13C-31P coupling. The corre-
sponding signal (singlet) for the free phosphine 3 is
observed at δ 126.1. Since to the best of our knowledge
neutral complexes of the general formula [(η6-arene)-
Rh(PR3)X] (X ) halide) are unknown,18 the existence of
14 illustrates quite clearly the supportive influence of
the functionalized phosphine 3 for the formation of half-
sandwich-type arenerhodium(I) derivatives.
Taking into account that the intermediate, initially
generated from 14 or 8 and carbon monoxide, is rather
labile and rapidly eliminates CO, we applied a different
methodology to isolate the dicarbonyl 15. We started
with 16 as the precursor, treated this in pentane with
carbon monoxide, and removed the solvent not in vacuo
but with a stream of CO. Using this procedure, we were
able to obtain a light yellow air-stable solid, correctly
analyzed as 15 in 95% yield (Scheme 3). The IR
spectrum of 15 displays (in contrast to that of 16, which
shows a single ν(CO) mode at 1962 cm-1) two stretching
vibrations at 2086 and 1999 cm-1 (in KBr), indicating
that the two CO ligands are in different environments.
In the 13C NMR spectrum of 15 also two CO resonances
appear at δ 184.8 and 181.1, the first of which has a
2
2J (P,C) coupling constant of 16.2 and the latter a J (P,C)
coupling constant of 112.5 Hz. The first signal is thus
assigned to the CO ligand cis and the second signal to
the CO ligand trans to the phosphine. Under argon (1
bar) compound 15 is stable both as a solid and in
Th e F ir st Str u ctu r a lly Ch a r a cter ized Dica r bo-
n ylr h od iu m (I) Com p lex, cis-[Rh Cl(CO)2(P R3)]. As
we assumed, in analogy to the behavior of phosphines
(19) (a) Singewald, E. T.; Mirkin, C. A.; Levy, A. D.; Stern, C. L.
Angew. Chem. 1994, 106, 2524-2526; Angew. Chem., Int. Ed. Engl.
1994, 33, 2473-2475. (b) Singewald, E. T.; Mirkin, C. A.; Stern, C. L.
Angew. Chem. 1995, 107, 1725-1728; Angew. Chem., Int. Ed. Engl.
1995, 34, 1624-1626. (c) Singewald, E. T.; Slone, C. S.; Stern, C. L.;
Mirkin, C. A.; Yap, G. P. A.; Liable-Sands, L. M.; Rheingold, A. L. J .
Am. Chem. Soc. 1997, 119, 3048-3056.
(20) (a) Gallay, J .; De Montauzon, D.; Poilblanc, R. J . Organomet.
Chem. 1972, 38, 179-197. (b) Rotondo, E.; Battaglia, G.; Giordano,
G.; Cusmano, F. P. J . Organomet. Chem. 1993, 450, 179-197. (c)
Hughes, R. P. In Comprehensive Organometallic Chemistry; Wilkinson,
G., Stone, F. G. A., Abel, E. W., Eds.; Pergamon: New York, 1982; p
300.
(16) van Gaal, H. L. M.; van den Bekerom, F. L. A. J . Organomet.
Chem. 1977, 134, 237-248.
(17) (a) Preparation: Werner, H.; Wolf, J .; Ho¨hn, A. J . Organomet.
Chem. 1985, 287, 395-407. (b) Molecular structure: Binger, P.; Haas,
J .; Glaser, G.; Goddard, R.; Kru¨ger, C. Chem. Ber. 1994, 127, 1927-
1929.
(18) The nearest analogue to 14, we are aware of, is the η6-toluene
complex [(η6-C6H5Me)Rh(C8H14){SnCl(N(SiMe3)2)2}], prepared from
[RhCl(C8H14)2]2 and Sn{N(SiMe3)2}2 in toluene: Hawkins, S. M.;
Hitchcock, P. B.; Lappert, M. F. J . Chem. Soc., Chem. Commun. 1985,
1592-1593.
(21) Giordano, G.; Rotondo, E. Polyhedron 1994, 13, 2507-2511.

1144 Organometallics, Vol. 23, No. 5, 2004
Canepa et al.
Sch em e 3a
F igu r e 3. Molecular diagram of compound 18. Selected
bond distances (Å) and angles (deg): Rh(1)-C(1) ) 2.059-
(3), C(1)-C(2) ) 1.480(4), Rh(1)-P(1) ) 2.2711(7), Rh(1)-
Cl(1) ) 2.3059(7), Rh(1)-Cl(2) ) 2.3561(6), Rh(1)-Cl(2A)
) 2.5257(6); Cl(1)-Rh(1)-Cl(2) ) 167.52(2), Cl(1)-Rh(1)-
Cl(2A) ) 87.19(2), Cl(1)-Rh(1)-P(1) ) 92.63(2), Cl(1)-Rh-
(1)-C(1) ) 87.77(9), Cl(2)-Rh(1)-P(1) ) 99.29(2), Cl(2)-
Rh(1)-C(1) ) 94.97(9), Cl(2)-Rh(1)-Cl(2A) ) 80.34(2),
P(1)-Rh(1)-C(1) ) 94.25(8), P(1)-Rh(1)-Cl(2A) ) 161.02-
(2), C(1)-Rh(1)-Cl(2A) ) 104.70(8), Rh(1)-C(1)-C(2) )
111.7(2), Rh(1)-Cl(2)-Rh(1A) ) 99.66(2).
a
L ) 2,6-Me2C6H3CH2CH2PtBu2.
1.9112(19) Å), which clearly reflects the trans influence
of the phosphine. The bulky alkyl substituent CH2-
CH2C6H3-2,6-Me2 is pointing away from the basal
coordination plane, which means that no interaction
between the arene ring and the metal center exists.
Moreover, an intermolecular π-stacking between the six-
membered rings can also be excluded.
The dicarbonyl derivative 15 as well as the dimer 16
react with phosphine 3 to give the monocarbonyl
complex 17 in nearly quantitative yields (see Scheme
3). The yellow air-stable solid is thermally remarkably
stable and decomposes at 188 °C. The 31P NMR spec-
trum displays one doublet resonance at δ 55.9, which
confirms that the two phosphine ligands are trans
disposed.
A Din u clea r Alk ylr h od iu m (III) Com p lex Bu ilt
u p by Tw o 14-Electr on Un its. The reaction of dimer
9 with HCl, undertaken to generate the five-coordinate
dichlorohydridorhodium(III) complex [RhHCl2(C2H4)(3)]
that would be structurally related to 13, led to a
surprising result. Passing a slow stream of dry HCl gas
through a suspension of 9 in CH2Cl2 for 10 s at room
temperature affords, after evaporation of the solvent,
an orange solid, the elemental analysis of which is in
agreement with the expected composition [RhHCl2-
(C2H4)(3)]. However, the 1H NMR spectrum of the
product shows no signals for hydridic and for olefinic
hydrogens but resonances at δ 4.60 and 1.14, which are
assigned to the CH2 and CH3 units of an ethyl group.
The 13C NMR spectrum equally displays two signals at
δ 23.7 and 24.6 for the CH2 and CH3 carbon atoms.
The existence of a Rh-C2H5 moiety in the isolated
product has been confirmed by an X-ray crystal struc-
ture analysis. The molecular diagram of 18 (Figure 3)
reveals that a dinuclear ethylrhodium(III) complex is
formed in which two 14-electron [RhCl2(C2H5)(3)] frag-
ments are linked by two bridging chloro ligands. The
midpoint of the planar Rh2Cl2 ring constitutes a center
of inversion. Since the terminal chlorides Cl(1) and Cl-
(3) lie exactly and the phosphorus atoms P(1) and P(2)
nearly in the plane of the Rh2Cl2 ring, the coordination
geometry around Rh(1) and Rh(2) can be best described
as square pyramidal with the C2H5 ligand in the apical
F igu r e 2. Molecular diagram of compound 15. Selected
bond distances (Å) and angles (deg): Rh(1)-C(1) ) 1.826-
(2), Rh(1)-C(2) ) 1.9112(19), Rh(1)-P(1) ) 2.4004(4), Rh-
(1)-Cl(1) ) 2.3414(5), C(1)-O(1) ) 1.135(3), C(2)-O(2) )
1.116(2); Rh(1)-C(1)-O(1) ) 172.8(2), Rh(1)-C(2)-O(2) )
177.1(2), Cl(1)-Rh(1)-P(1) ) 92.354(16), Cl(1)-Rh(1)-C(1)
) 171.60(8), Cl(1)-Rh(1)-C(2) ) 86.43(6), C(1)-Rh(1)-
C(2) ) 88.19(9), C(1)-Rh(1)-P(1) ) 93.31(6), C(2)-Rh(1)-
P(1) ) 177.08(6).
solution, which is in sharp contrast to observations
reported for other rhodium(I) compounds cis-[RhCl-
(CO)2(PR3)].20,22 In agreement with the assumption that
15 is an intermediate in the formation of 16 from 8 and
14, it is easily converted to 16 in vacuo either in solution
or in the solid state.
The result of the X-ray crystal structure analysis of
15 is outlined in Figure 2. As expected, the coordination
geometry around rhodium is square planar with bond
angles P-Rh-Cl and P-Rh-C(1), which are slightly
larger than 90°, and bond angles C(2)-Rh-Cl and
C(1)-Rh-C(2), which are slightly smaller than 90°. The
effect of the sterically demanding phosphine is obvious.
The Rh-C(2)-O(2) axis is nearly linear (177.1(2)°),
while the Rh-C(1)-O(1) axis is somewhat bent (172.8-
(2)°), which could equally be due to the steric hindrance
between the cis-disposed CO ligand and the substituents
at phosphorus. The most noteworthy feature, however,
is the difference in the Rh-C bond lengths (1.826(2) vs
(22) Arena, C. G.; Faraone, F.; Lanfranchi, M.; Rotondo, E.; Tirip-
icchio, A. Inorg. Chem. 1992, 31, 4797-4802.

Rh(I) and Rh(III) Complexes with a Bulky Phosphine
Organometallics, Vol. 23, No. 5, 2004 1145
Sch em e 4a
Sch em e 5a
a
L ) 2,6-Me2C6H3CH2CH2PtBu2.
Sch em e 6a
a
L ) 2,6-Me2C6H3CH2CH2PtBu2.
position. The ethyl groups of the two fragments are
located in a trans configuration: i.e., on opposite sides
of the Rh2Cl2 plane. The bond length Rh(1)-C(1) of
2.059(3) Å is comparable to those in other alkylrhodium-
(III) compounds23 but significantly shorter (ca. 0.11 Å)
than in the Milstein complex [RhCl(CH3)(C6H-2,4-
(CH2PtBu2)2-3,5-Me2-κ3P,C,P)].4a
The reactivity of the dinuclear ethylrhodium(III)
derivate 18 is quite unusual. Treatment of 18 with
phosphine 3, undertaken to prepare the mononuclear
five-coordinate complex [RhCl2(C2H5)(3)2] via chloride-
bridge cleavage, gives the dichloro hydrido compound
13 (Scheme 4). To explain the formation of this molecule,
we assume that in solution an equilibrium between a
(possibly monomeric) Rh(C2H5) and RhH(C2H4) isomer
exists24 and that 13 is formed from the latter by olefin/
phosphine exchange.
a
L ) 2,6-Me2C6H3CH2CH2PtBu2; S ) acetone.
spectra of 20 show, similarly to those of 14, the signals
for the proton and the carbon nuclei of the CH unit trans
to the ipso C atom of the ring at relatively high chemical
shifts, indicating a pronounced shielding of this CH unit
by the metal center.
The cyclooctene ligand of 20 is not firmly bound, and
upon stirring a solution of 20 in CH2Cl2 under an ethene
atmosphere can be substituted by C2H4. However, the
reaction is rather slow, probably due to the fact that
the rhodium center in the starting material has an 18-
1
electron count. The H NMR spectrum of the generated
The same (ethene)hydridorhodium(III) intermediate
is possibly also involved in the reaction of 18 with CO.
Stirring a solution of 18 in CH2Cl2 under a CO atmo-
sphere (1 bar) for 1 h at room temperature affords a
light yellow solution which contains, according to the
IR and 31P NMR spectra, the dicarbonyl complex 15.
Careful investigation of the gas phase indicated that
ethene and HCl were eliminated. We assume that the
postulated intermediate [RhHCl2(C2H4)(3)] reacts with
CO to give initially [RhHCl2(CO)(3)], which in the
presence of CO eliminates HCl and with a second
molecule of carbon monoxide yields 15.
Ha lf-Sa n d w ich -Typ e Com p lexes w ith P h osp h in e
3 a s Ch ela tin g Liga n d . Following our research on the
coordination capabilities of R2P(CH2)2C6H5 (R ) iPr,
tBu),1,3 we were also interested in investigating the
behavior of the highly reactive bis(cyclooctene)rhodium-
(I) cation 19 toward 3. It reacts with an equimolar
amount of 3 by displacement of one cyclooctene and both
acetone ligands to give the half-sandwich-type complex
20, being isolated as an orange, slightly air-sensitive
solid in 94% yield (Scheme 5). The 1H and 13C NMR
Rh(C2H4) complex 21, being an orange solid, displays
at room temperature only a broadened singlet for the
C2H4 protons at δ 3.25, which indicates that under these
conditions the rotation of the olefin around the Rh-C2H4
axis is quite fast. A similar dynamic behavior has also
been observed for the analogue of 21 with iPr2P-
(CH2)2C6H5 instead of 3 as a ligand and studied in detail
by VT-NMR spectroscopy.1
The conversion of the (olefin)rhodium(I) derivatives
20 and 21 to the cationic dihydridorhodium(III) com-
pound 23 proceeds stepwise. Stirring a solution of one
of the starting materials in acetone for 12 h under a
hydrogen atmosphere leads to a smooth change of color
from orange-red to brown-yellow and, after partial
evaporation of the solvent and addition of diethyl ether,
yields a light brown, moderately air-stable solid with
the analytical composition corresponding to 23 (Scheme
1
6). If, however, the reaction is monitored by H or 31P
NMR spectroscopy, the formation of the intermediate
22, also containing two hydride ligands, can be observed.
Typical features of 22 are the high-field signal (doublet
1
of doublets) in the H NMR spectrum at δ -23.40 and
the doublet resonance in the 31P NMR spectrum at δ
92.1. The half-sandwich-type compound 23 is soluble in
nitromethane and dichloromethane but is reconverted
to the solvated species 22 in the presence of excess
acetone. Both 22 and 23 behave in CH3NO2 as 1:1
electrolytes. The dihydrido complex 23, which can be
stored under argon at -20 °C for a few days, shows a
characteristic 1H NMR signal for the Rh-H protons at
δ -12.51 and thus ca. 11 ppm downfield compared with
22.
(23) (a) Troughton, P. G. H.; Skapski, A. C. J . Chem. Soc., Chem.
Commun. 1968, 575-576. (b) Takenaka, A.; Syal, S. K.; Sasada, Y.;
Omura, T.; Ogoshi, H.; Yoshida, Z.-I. Acta Crystallogr., Sect. B 1976,
32, 62-65. (c) Doyle, M. J .; Mayanza, A.; Bonnet, J . J .; Kalck, P.;
Poilblanc, R. J . Organomet. Chem. 1978, 146, 293-310. (d) van der
Zeijden, A. A. H.; van Koten, G.; Ernsting, J . M.; Elsevier, C. J .;
Krijnen, B.; Stam, C. H. J . Chem. Soc., Dalton Trans. 1989, 317-324.
(e) Cohen, R.; van der Boom, M. E.; Shimon, L. J . W.; Rozenberg, H.;
Milstein, D. J . Am. Chem. Soc. 2000, 122, 7723-7734.
(24) (a) Werner, H.; Feser, R. Angew. Chem. 1979, 91, 171-172;
Angew. Chem., Int. Ed. Engl. 1979, 18, 157-158. (b) Werner, H.; Feser,
R. J . Organomet. Chem. 1982, 232, 351-370. (c) Vigalok, A.; Kraatz,
H.-B.; Konstantinovsky, L.; Milstein, D. Chem. Eur. J . 1997, 3, 253-
260. (d) van der Boom, M. E.; Liou, S.-Y.; Ben-David, Y.; Gozin, M.;
Milstein, D. J . Am. Chem. Soc. 1998, 120, 13415-13421. (e) van der
Boom, M. E.; Higgitt, C. L.; Milstein, D. Organometallics 1999, 18,
2413-2419.
The tris(solvato)rhodium(III) compound 22, if gener-
ated from 23 and acetone, is stable under hydrogen for
hours but rearranges, after the H2 atmosphere is re-

1146 Organometallics, Vol. 23, No. 5, 2004
Canepa et al.
Sch em e 7
placed by argon, very slowly to the chelate complex 24
(Scheme 7). The conversion is completed after storing
a solution of 23 in acetone for ca. 4 weeks at room
temperature. Since in the absence of acetone compound
24 decomposes quite rapidly, it could only be character-
effected by the π-electrons of the phenyl ring attached
to the CdC double bond of the styrene. Similarly to 26,
the alkyne complex 27 is an orange air-stable solid
which slowly decomposes in solvents such as acetone
and dichloromethane. Since the IR spectrum of 27
displays the ν(tCH) and ν(CtC) stretching modes at,
respectively, 3163 and 1827 cm-1, there is no doubt that
during the synthesis no isomerization of the alkyne to
the corresponding vinylidene has taken place.
By attempting to initiate photochemically a rear-
rangement of 27 to the isomer [(η6-2,6-Me2C6H3CH2-
CH2PtBu2-κP)Rh(dCdCHPh)]PF6, we received a sur-
prising result. UV irradiation of a solution of 27 in
acetone for 72 h at room temperature led to a gradual
change of color from orange to yellow and gave, after
removal of the solvent, the carbonyl complex 28 in 91%
yield. If, instead of acetone, CH2Cl2 is used as the
solvent, only decomposition of the starting material
occurs. We assume that, during the extended photo-
chemical process, a C-C bond cleavage of the acetone
ligand takes place, similar to that in a Norrish type I
reaction.25 Typical spectroscopic data of 28 (being a light
yellow, air-stable solid) are the ν(CO) absorption at 2001
cm-1 in the IR and the doublet of doublets resonance
for the carbonyl carbon atom at δ 185.9 in the 13C NMR
spectrum. An independent experiment, carried out in
an NMR tube, confirmed that 28 is also generated upon
UV irradiation of a solution of 26 in the presence of CO.
1
ized by spectroscopic techniques. The H and 13C NMR
spectra of 24 display in acetone-d6 only the signals for
phosphine 3, indicating that obviously a fast exchange
between coordinated and free acetone occurs. The as-
sumption that the phosphine is linked via the phospho-
rus atom and the arene ring to the metal center is
strongly supported by the NMR parameters for the CH
unit trans to the CH2CH2PtBu2 substituent at the ring,
which are very similar to those of 25-28 (see below).
Addition of [NnBu4]Cl to an acetone solution of 24 leads
to an exchange of OCMe2 for chloride and gives the
neutral half-sandwich-type complex 14. If this com-
pound is dissolved in CD2Cl2 and the solution treated
with acetone, the cation of 24 is regenerated.
By attempting to facilitate the elimination of H2 from
22, the starting material 23 was treated with 3,3-
dimethyl-1-butene, which is known to be a good acceptor
for dihydrogen. However, instead of 24 the half-sandwich-
type compound 25 was isolated as a yellow solid in 78%
yield. In contrast to 24, the olefin derivative is surpris-
ingly stable, decomposing at 110 °C, and can be handled
for a short period of time in air. Although it is less stable
in solution, the NMR spectra clearly confirm that an
analogue of the ethene compound 21 is present.
The dihydrido complex 23 reacts not only with 3,3-
dimethyl-1-butene but also with phenylacetylene. If an
excess of HCtCPh is used, the alkynerhodium(I) com-
pound 27 is formed exclusively. With an equimolar
amount of phenylacetylene, the styrene complex 26 is
initially generated, which subsequently reacts with the
alkyne to give 27. A clean synthesis of 26 is possible by
treatment of 23 with styrene, which affords the product
as an orange air-stable solid in 95% isolated yield (see
Scheme 7). Regarding the spectroscopic data of 26, a
typical feature is that in the 1H NMR spectrum two
signals for the protons in 3- and 5-positions at the ring
appear, one of them at unusually high field at δ 5.03.
We assume that for steric reasons only this proton is
Con clu d in g Rem a r k s
The work presented in this paper illustrates that at
least in some respects the title phosphine 3 behaves
differently compared with the less bulky analogues
iPr2P(CH2)2C6H5 and tBu2P(CH2)2C6H5, respectively.
This statement is particularly supported by two results.
The first is the formation and molecular structure of
the dinuclear alkylrhodium(III) compound 18, which is
built up by two 14-electron [RhCl2(C2H5)(PR3)] units.
Although there are a number of rhodium complexes
(25) Carey, F. A.; Sundberg, R. J . In Organische Chemie: Ein
weiterfu¨hrendes Lehrbuch; Scha¨fer, H. J ., Hoppe, D., Erker, G., Eds.;
Wiley-VCH: Weinheim, Germany, 1995.

Rh(I) and Rh(III) Complexes with a Bulky Phosphine
Organometallics, Vol. 23, No. 5, 2004 1147
[RhCl(L)2]2 or [RhCl(L)(L′)]2 known,26 which similarly
to 18 are also composed of two 14-electron fragments,
in all of these compounds the metal is in the oxidation
state +I and not +III. Independently from our work,
Budzelaar, Gal, et al. reported the preparation and
structural characterization of an analogue of 18, with
a bulky chelating â-diiminato ligand (instead of one
chloro ligand and phosphine 3), two phenyl instead of
two ethyl groups, and two bridging bromides.27 In
contrast to 18, this complex was obtained from the 14-
electron rhodium(I) monomer [Rh(â-diiminate-κ2)(C8H14)]
by oxidative addition with bromobenzene. From a
structural point of view, both 18 and the Budzelaar-
Gal compound are remarkable indeed. The nearest
relative of these dinuclear complexes, we are aware of,
is the mononuclear hydridosilylrhodium(III) compound
[RhHCl{Si(CH2Ph)3}(PiPr3)]2, prepared by oxidative
addition of HSi(CH2Ph)3 to [RhCl(PiPr3)2]2.28 With
regard to 18, the unusual feature is that in solution
obviously an equilibrium between a Rh(C2H5) and a
RhH(C2H4) isomer exists, of which the latter is respon-
sible for the pronounced reactivity of 18 toward CO and
the title phosphine 3.
The second significant aspect constitutes the isolation
of the mononuclear four-coordinate dicarbonyl com-
pound 15, representing, to the best of our knowledge,
the first structurally characterized rhodium(I) complex
of the general composition cis-[RhCl(CO)2(PR3)]. Al-
though it has been reported by several groups that
compounds of this type can be generated,20,22 evidence
for the exact configuration with cis-disposed CO ligands
was lacking. In agreement with previous observations,
the dicarbonyl complex is quite labile and readily
eliminates one CO unit to give 16 (see Scheme 3).
However, the abstraction of the remaining CO ligand
is kinetically hindered, and thus compound 16 is not
an appropriate starting material for complex 14. Whether
this novel half-sandwich-type compound, for which
under appropriate conditions a change in coordination
of the title phosphine 3 from a chelating to a terminal
P-bonded mode seems possible, can be used as a catalyst
or a catalyst precursor should be proved by further
investigations.
NMR spectra were recorded (if not otherwise stated) at room
temperature on Bruker AC 200, Bruker DRX 300, and Bruker
AMX 400 instruments, IR spectra were recorded on a IFS 25
FT-IR infrared spectrometer, and mass spectra were recorded
on a Finnigan MAT 90 (70 eV) or on a Hewlett-Packard G 1800
GCD instrument. Coupling constants are given in hertz.
Abbreviations used: s, singlet; d, doublet; t, triplet; m,
multiplet; v, virtual coupling; br, broadened signal; N ) 3J (PH)
5
3
+ J (PH) or 1J (PC) + J (PC). Melting points were measured
by differential thermal analysis (DTA). The molar conductivity
ΛM was determined in nitromethane.
P r ep a r a tion of (2,6-Me2C6H3CH2CH2)(tBu )P Cl (2). A
solution of 2-(2,6-dimethylphenyl)ethyl chloride (19.7 g, 0.12
mol) in THF (40 mL) was added dropwise to a suspension of
Mg (2.8 g, 0.12 mol) in THF (10 mL) at room temperature.
The reaction mixture was warmed under reflux for 30 min
and after cooling to room temperature stirred for 1 h. The
solution thus formed solution was added dropwise at 0 °C to
a solution of tBuPCl2 (18.6 g, 0.12 mol) in THF (60 mL), which
led to the precipitation of a white solid. After the mixture
was warmed to room temperature, the solvent was evaporated
and the residue was extracted six times with diethyl ether
(80 mL each). The combined extracts were brought at only
slightly reduced preasure to dryness, and the remaining
oil was distilled at 0.002 bar. A colorless liquid (bp 106-108
°C) was obtained, which became a solid if it was stored in
the refrigerator. Yield: 13.5 g (45%). (For NMR data see ref
5.)
P r ep a r a tion of 2,6-Me2C6H3CH2CH2P tBu 2 (3). A solution
of 2 (13.0 g, 50.7 mmol) in benzene (40 mL) was treated
dropwise at 5 °C with a 1.6 M solution of tBuLi (44 mL, 70.4
mmol) in pentane. After the reaction mixture was warmed to
room temperature, it was stirred for 8 h and then hydrolyzed
with argon-saturated water (20 mL). Diethyl ether (40 mL)
was added, and the two phases were separated. The organic
phase was dried with Na2SO4 and then filtered. The solvent
was evaporated in vacuo and the oily residue distilled at 0.002
bar. A colorless liquid (bp 105 °C) was obtained. Yield: 11.5 g
(81%). MS (CI): m/z 279 (M+ + H), 278 (M+). (For NMR data
see ref 5.)
P r ep a r a tion of [(2,6-Me2C6H3CH2CH2)P (CH3)tBu 2]I (4).
A solution of 3 (560 mg, 2.01 mmol) in hexane (20 mL) was
treated with methyl iodide (144 µL, 2.30 mmol) and stirred
for 3 h at room temperature. A white solid precipitated, which
was separated from the mother liquor, washed twice with
diethyl ether (10 mL each) and twice with pentane (10 mL
1
each), and dried. Yield: 763 mg (90%). Mp: 258 °C. H NMR
(200 MHz, CD3NO2): δ 7.06 (s, 3 H, C6H3), 3.05 (m, 2 H,
PCH2CH2), 2.35 (s, 6 H, C6H3(CH3)2), 2.31 (m, 2 H, PCH2), 1.99
(d, J (PH) ) 11.7 Hz, 3 H, PCH3), 1.53 (d, J (PH) ) 15.7 Hz, 18
H, PCCH3). 13C NMR (50.3 MHz, CD3NO2): δ 137.6 (s, ortho
C of C6H3), 137.5 (d, J (PC) ) 13.6 Hz, ipso C of C6H3), 130.0
(s, meta C of C6H3), 128.5 (s, para C of C6H3), 34.9 (d, J (PC) )
38.3 Hz, PCCH3), 27.0 (s, PCCH3), 25.0 (d, J (PC) ) 5.2 Hz,
PCH2CH2), 20.2 (s, C6H3(CH3)2), 16.9 (d, J (PC) ) 37.7 Hz,
PCH2), -0.1 (d, J (PC) ) 48.1 Hz, PCH3). 31P NMR (81.0 MHz,
CD3NO2): δ 48.9 (s). Anal. Calcd for C19H34IP: C, 54.29; H,
8.15. Found: C, 53.98; H, 8.10.
P r ep a r a tion of [(2,6-Me2C6H3CH2CH2)P (H)tBu 2]Cl (5).
A slow stream of gaseous HCl was passed for 60 s through a
solution of 3 (432 mg, 1.55 mmol) in hexane (10 mL) at room
temperature. A white solid precipitated, which was separated
from the mother liquor, washed twice with pentane (5 mL
each), and dried. Yield: 454 mg (93%). Mp: 118 °C. (For NMR
data see ref 5.)
Exp er im en ta l Section
All reactions were carried out under an atmosphere of argon
by Schlenk techniques. The starting materials 1,29 tBuPCl2,30
6,31 7,32 and 1933 were prepared as described in the literature.
(26) (a) Dickson, R. S. Organometallic Chemistry of Rhodium and
Iridium; Academic Press: London, New York, 1983; p 58. (b) J ardine,
F. H.; Sheridan, P. S. In Comprehensive Coordination Chemistry;
Wilkinson, G., Gillard, R. D., McCleverty, J . A., Eds.; Pergamon: New
York, 1987; p 908.
(27) Willems, S. T. H.; Budzelaar, P. H. M.; Moonen, N. N. P.; de
Gelder, R.; Smits, J . M. M.; Gal, A. W. Chem. Eur. J . 2002, 6, 1310-
1320.
(28) Osakada, K.; Koizumi, T.; Yamamoto, T. Bull. Chem. Soc. J pn.
1997, 70, 189-195.
(29) Bream, J . B.; Picard, C. W.; White, T. G.; Lauener, H. J . Med.
Chem. 1970, 13, 1051-1057.
(30) Field, M.; Stelzer, O.; Schmutzler, R. Inorg. Synth. 1973, 14,
4-9.
P r ep a r a tion of [Rh (µ-Cl)(C8H14)(2,6-Me2C6H3CH2CH2-
P tBu 2-KP )]2 (8). A suspension of 6 (307 mg, 0.43 mmol) in
benzene (3 mL) was treated with a solution of 3 (238 mg, 0.86
mmol) in benzene (7 mL) at room temperature. After the
reaction mixture was stirred for 5 min, an orange solution was
formed. The solvent was evaporated in vacuo, and the residue
(31) van der Ent, A.; Onderdelinden, A. L. Inorg. Synth. 1973, 14,
92-95.
(32) Cramer, R. Inorg. Synth. 1974, 15, 14-16.
(33) (a) Windmu¨ller, B.; Wolf, J .; Werner, H. J . Organomet. Chem.
1995, 502, 147-161. (b) Windmu¨ller, B.; Nu¨rnberg, O.; Wolf, J .;
Werner, H. Eur. J . Inorg. Chem. 1999, 613-619.

1148 Organometallics, Vol. 23, No. 5, 2004
Canepa et al.
was dissolved in pentane (6 mL). A yellow solid precipitated,
which was filtered, washed with pentane (3 mL), and dried.
Yield: 365 mg (81%). Mp: 64 °C dec. 1H NMR (200 MHz,
C6D6): δ 6.93 (m, 6 H, C6H3), 3.54 (m, 4 H, dCH of C8H14),
2.85 (m, 4 H, PCH2CH2), 2.52 (m, 4 H, CH2 of C8H14), 2.56 (s,
12 H, C6H3(CH3)2), 1.68-1.17 (m, 24 H, PCH2 and CH2 of
C8H14), 1.53 (d, J (PH) ) 12.4 Hz, 36 H, PCCH3). 13C NMR (50.3
MHz, C6D6): δ 140.0 (d, J (PC) ) 8.4 Hz, ipso C of C6H3), 135.8
(s, ortho C of C6H3), 129.1 (s, meta C of C6H3), 126.5 (s, para
C of C6H3), 59.2 (d, J (RhC) ) 17.5 Hz, dCH of C8H14), 37.4 (d,
J (PC) ) 17.5 Hz, PCCH3), 31.3 (d, J (PC) ) 3.9 Hz, PCCH3),
21.2 (s, C6H3(CH3)2), 18.8 (d, J (PC) ) 22.7 Hz, PCH2); the
signals of PCH2CH2 and the CH2 carbon atoms of C8H14 could
not be exactly located. 31P NMR (81.0 MHz, C6D6): δ 65.5 (d,
J (RhP) ) 185.7 Hz, cis dimer), 64.8 (d, J (RhP) ) 188.2 Hz,
trans dimer). Anal. Calcd for C52H90P2Cl2Rh2: C, 59.26; H,
8.61. Found: C, 59.27; H, 8.46.
vacuo, and the yellow residue was washed three times with
pentane (10 mL each) and dried. The NMR spectra showed
that the solid consisted of equal quantities of 5 and 12.
Attempts to separate the two compounds failed. Spectroscopic
data for 12 are as follows. IR (CH2Cl2): ν(RhH) 2146 cm-1. 1H
NMR (200 MHz, CD2Cl2): δ 6.93 (m, 6 H, C6H3), 3.05 (m, 4 H,
PCH2CH2), 2.43 (s, 12 H, C6H3(CH3)2), 2.16 (m, 4 H, PCH2),
1.47 (d, J (PH) ) 13.8 Hz, 36 H, PCCH3), -22.48 (dd, J (RhH)
) 21.7, J (PH) ) 11.8 Hz, 2 H, RhH). 13C NMR (50.3 MHz,
CD2Cl2): δ 139.9 (d, J (PC) ) 12.3 Hz, ipso C of C6H3), 137.2
(s, ortho C of C6H3), 128.6 (s, meta C of C6H3), 125.8 (s, para
C of C6H3), 37.6 (d, J (PC) ) 20.1 Hz, PCCH3), 30.9 (br s,
PCCH3), 26.4 (s, PCH2CH2), 21.8 (s, C6H3(CH3)2), 14.3 (d, J (PC)
) 21.4 Hz, PCH2). 31P NMR (81.0 MHz, CD2Cl2): δ 77.5 (br d,
J (RhP) ) 142.4 Hz).
P r ep a r a t ion of [R h H Cl2(2,6-Me2C6H 3CH 2CH 2P tBu 2-
KP )2] (13). A solution of 8 (112 mg, 0.11 mmol) in benzene (6
mL) was treated with 5 (67 mg, 0.21 mmol), and the mixture
was then stirred for 2 h at 60 °C. An orange solution was
formed, from which, after cooling to 20 °C, the solvent was
evaporated in vacuo. The remaining orange solid was washed
twice with diethyl ether (5 mL each) and twice with pentane
(5 mL each) and dried. Yield: 115 mg (71%). Mp: 103 °C dec.
Anal. Calcd for C36H63P2Cl2Rh: C, 59.10; H, 8.68. Found: C,
59.53; H, 8.50. (For NMR data see ref 5.)
P r epar ation of [(η6-2,6-Me2C6H3CH2CH2P tBu 2-KP )Rh Cl]
(14). A suspension of 5 (225 mg, 0.71 mmol) in diethyl ether
(7 mL) was treated with a solution of 8 (377 mg, 0.36 mmol)
in diethyl ether (25 mL), and the mixture was stirred for 1 h
at room temperature. The solvent was evaporated in vacuo,
and the residue was washed three times with pentane (10 mL
each) and dried. It was then dissolved in dichloromethane (2
mL), and the solution was chromatographed on Al2O3 (acidic,
activity grade III, length of column 4 cm). With dichlo-
romethane a green-yellow fraction was eluted, from which the
solvent was removed in vacuo. The oily residue was washed
three times with pentane (6 mL each). After it was stored at
-30 °C for 6 h, a green microcrystalline solid was obtained.
Yield: 169 mg (57%). Mp: 58 °C dec. 1H NMR (200 MHz, CD2-
Cl2): δ 6.59 (m, 2 H, meta H of C6H3), 5.13 (m, 1 H, para H of
C6H3), 2.17 (s, 6 H, C6H3(CH3)2), 2.15-1.94 (m, 4 H, PCH2 and
PCH2CH2), 1.36 (d, J (PH) ) 13.5 Hz, 18 H, PCCH3). 13C NMR
(50.3 MHz, CD2Cl2): δ 113.0 (d, J (PC) ) 4.6 Hz, ortho C of
C6H3), 109.3 (s, meta C of C6H3), 94.1 (dd, J (PC) ) 12.0, J (RhC)
) 1.9 Hz, para C of C6H3), 85.6 (dd, J (PC) ) 9.3, J (RhC) ) 2.8
Hz, ipso C of C6H3), 37.2 (dd, J (PC) ) 17.6, J (RhC) ) 1.9 Hz,
PCCH3), 32.7 (d, J (PC) ) 21.3 Hz, PCH2), 29.6 (d, J (PC) ) 3.7
Hz, PCCH3), 27.6 (d, J (PC) ) 4.6 Hz, PCH2CH2), 19.3 (s, C6H3-
(CH3)2). 31P NMR (81.0 MHz, CD2Cl2): δ 108.7 (d, J (RhP) )
203.5 Hz). Anal. Calcd for C18H31ClPRh: C, 51.87; H, 7.50.
Found: C, 51.84; H, 7.64.
P r ep a r a t ion of [R h (µ-Cl)(C2H 4)(2,6-Me2C6H 3CH 2CH 2-
P tBu 2-KP )]2 (9). This compound was prepared as described
for 8 from 7 (94 mg, 0.24 mmol) and 3 (135 mg, 0.48 mmol) in
benzene (8 mL). A yellow microcrystalline solid was obtained.
Yield: 199 mg (93%). Mp: 77 °C dec. Anal. Calcd for C40H70P2-
Cl2Rh2: C, 54.00; H, 7.93. Found: C, 53.97; H, 7.87. (For NMR
data see ref 5.)
Gen er a tion of [Rh H 2(µ-Cl)(2,6-Me2C6H3CH2CH2P tBu 2-
K-P )]2 (10). A suspension of 9 (23 mg, 0.03 mmol) in CD2Cl2
(0.5 mL) was stirred under a hydrogen atmosphere at room
temperature. After a few minutes, a yellow solution was
formed, which was shown by the NMR spectra to contain
exclusively compound 10. Since all attempts to isolate this
compound failed or gave 11, it was characterized spectroscopi-
cally. IR (CH2Cl2): ν(RhH) 2149, 2125 cm-1 1H NMR (200
.
MHz, CD2Cl2): δ 6.97 (m, 6 H, C6H3), 3.05 (dt, J (PH) ) 12.8,
J (HH) ) 3.9 Hz, 4 H, PCH2CH2), 2.38 (s, 12 H, C6H3(CH3)2),
1.86 (m, 4 H, PCH2), 1.43 (d, J (PH) ) 13.8 Hz, 36 H, PCCH3),
-21.50 (br s, 4 H, RhH). 13C NMR (100.6 MHz, CD2Cl2): δ
140.1 (d, J (PC) ) 13.4 Hz, ipso C of C6H3), 136.6 (s, ortho C of
C6H3), 128.4 (s, meta C of C6H3), 126.0 (s, para C of C6H3),
36.6 (d, J (PC) ) 21.0 Hz, PCCH3), 30.5 (d, J (PC) ) 2.9 Hz,
PCCH3), 28.9 (s, PCH2CH2), 25.7 (d, J (PC) ) 25.7 Hz, PCH2),
20.8 (s, C6H3(CH3)2). 31P NMR (81.0 MHz, CD2Cl2, 293 K): δ
96.4 (br s). 31P NMR (81.0 MHz, CD2Cl2, 313 K): δ 97.8 (d,
J (RhP) ) 162.8 Hz).
P r ep a r a t ion of [R h H 2Cl(2,6-Me2C6H 3CH 2CH 2P tBu 2-
KP )2] (11). (a) A suspension of 7 (46 mg, 0.12 mmol) in benzene
(3 mL) was treated with a solution of 3 (132 mg, 0.47 mmol)
in benzene (6 mL), and the mixture was stirred for 8 h under
a hydrogen atmosphere (1 bar). The solvent was evaporated
in vacuo and the residue suspended in pentane (6 mL). A
yellow microcrystalline solid precipitated, which was filtered,
washed twice with pentane (3 mL each), and dried. Yield: 150
mg (90%).
P r ep a r a t ion of cis-[R h Cl(CO)2(2,6-Me2C6H 3CH 2CH 2-
P tBu 2-KP )] (15). A suspension of 16 (67 mg, 0.08 mmol) in
pentane (7 mL) was stirred under a CO atmosphere (1 bar)
for 1 h at room temperature. A light yellow solution was
formed, from which the solvent was evaporated with a stream
of CO. A light yellow solid was isolated. Yield: 68 mg (95%).
(b) 11 was obtained analogously as described for (a), from 9
(77 mg, 0.09 mmol) and 3 (48 mg, 0.17 mmol). Yield: 111 mg
(94%). Mp: 104 °C dec. IR (KBr): ν(RhH) 2122 cm-1. Anal.
Calcd for C36H64P2ClRh: C, 62.02; H, 9.25. Found: C, 61.96;
H, 9.01. (For NMR data see ref 5.)
Mp: 94 °C dec. IR (KBr): ν(CO) 2086, 1999 cm-1 1H NMR
.
Rea ction of Com p ou n d 11 w ith Eth en e. A solution of
11 (77 mg, 0.11 mmol) in pentane (5 mL) was stirred under
an ethene atmosphere (1 bar) for 3 days. A yellow solid
precipitated, which was filtered and then dissolved in C6D6
(0.5 mL). The 1H and 31P spectra confirmed that both the
ethene complex 9 and the phosphine 3 were formed. If the
solution was stored under H2 (1 bar), the starting material 11
was regenerated.
(400 MHz, CD2Cl2): δ 7.00 (s, 3 H, C6H3), 3.02 (m, 2 H,
PCH2CH2), 2.44 (s, 6 H, C6H3(CH3)2), 2.31 (m, 2 H, PCH2), 1.48
(d, J (PH) ) 13.2 Hz, 18 H, PCCH3). 13C NMR (100.6 MHz,
CD2Cl2): δ 184.8 (dd, J (RhC) ) 71.5, J (PC) ) 16.2 Hz, CO
trans to Cl), 181.1 (dd, J (PC) ) 112.5, J (RhC) ) 58.2 Hz, CO
cis to Cl), 139.1 (d, J (PC) ) 12.4 Hz, ipso C of C6H3), 136.9 (s,
ortho C of C6H3), 128.8 (s, meta C of C6H3), 126.4 (s, para C of
C6H3), 36.0 (d, J (PC) ) 17.2 Hz, PCCH3), 30.6 (d, J (PC) ) 3.8
Hz, PCCH3), 26.6 (s, PCH2CH2), 21.3 (s, C6H3(CH3)2), 19.5 (d,
J (PC) ) 15.3 Hz, PCH2). 31P NMR (162.0 MHz, CD2Cl2): δ
57.8 (d, J (RhP) ) 122.1 Hz). Anal. Calcd for C20H31O2PClRh:
C, 50.81; H, 6.61. Found: C, 50.83; H, 6.68.
Gen er ation of [Rh HCl(µ-Cl)(2,6-Me2C6H3CH2CH2P tBu 2-
KP )]2 (12). A suspension of 5 (144 mg, 0.46 mmol) in diethyl
ether (5 mL) was treated with a solution of 8 (241 mg, 0.23
mmol) in diethyl ether (15 mL), and the mixture was stirred
for 1 h at room temperature. The solvent was evaporated in

Rh(I) and Rh(III) Complexes with a Bulky Phosphine
Organometallics, Vol. 23, No. 5, 2004 1149
P r ep a r a t ion of [R h (µ-Cl)(CO)(2,6-Me2C6H 3CH 2CH 2-
P tBu 2-KP )]2 (16). (a) A suspension of 8 (114 mg, 0.11 mmol)
in pentane (8 mL) was stirred under a CO atmosphere at room
temperature. In less than 10 s a light yellow solution was
formed, the 31P NMR spectrum of which confirmed that
compound 15 was generated. While the solution was concen-
trated in vacuo, a light yellow solid precipitated, which was
shown by the NMR spectra to consist of a mixture of cis-16
(δP 79.4, J (RhP) ) 172.9 Hz; ca. 10%) and trans-16 (δP 78.6,
J (RhP) ) 174.6 Hz; ca. 90%). After the precipitate was
suspended in pentane (10 mL), part of the solid (mainly the
cis dimer) was dissolved. The solvent was evaporated in vacuo;
the remaining light yellow solid (consisting only of the trans
dimer) was washed twice with pentane (5 mL each) and dried.
Yield: 85 mg (87%).
(b) A solution of 14 (54 mg, 0.13 mmol) in dichloromethane
(2 mL) was stirred under a CO atmosphere (1 bar). In less
than 10 s a change of color from red-brown to light yellow
occurred. The solution was worked up as described for (a).
Yield: 47 mg (81%). Mp: 195 °C dec. IR (KBr): ν(CO) 1962
cm-1. 1H NMR (400 MHz, CD2Cl2): δ 6.99 (m, 6 H, C6H3), 3.15
(m, 4 H, PCH2CH2), 2.43 (s, 12 H, C6H3(CH3)2), 2.15 (m, 4 H,
PCH2), 1.52 (d, J (PH) ) 13.2 Hz, 36 H, PCCH3). 13C NMR
(100.6 MHz, CD2Cl2): δ 186.8 (dd, J (RhC) ) 80.2, J (PC) )
17.2 Hz, CO), 139.2 (d, J (PC) ) 13.4 Hz, ipso C of C6H3), 136.8
(s, ortho C of C6H3), 128.8 (s, meta C of C6H3), 126.3 (s, para
C of C6H3), 37.1 (d, J (PC) ) 20.0 Hz, PCCH3), 30.6 (d, J (PC)
) 2.9 Hz, PCCH3), 26.9 (s, PCH2CH2), 23.7 (d, J (PC) ) 18.1
Hz, PCH2), 21.3 (s, C6H3(CH3)2). 31P NMR (162.0 MHz, CD2-
Cl2): δ 78.6 (d, J (RhP) ) 174.6 Hz). Anal. Calcd for C38H62O2P2-
Cl2Rh2: C, 51.31; H, 7.02. Found: C, 51.61; H, 7.09.
(CH3)2), 2.20 (m, 4 H, PCH2), 1.63 (d, J (PH) ) 13.2 Hz, 36 H,
PCCH3), 1.15 (t, J (HH) ) 7.1 Hz, 6 H, CH2CH3). 13C NMR (75.4
MHz, CD2Cl2, 293 K): δ 138.9 (d, J (PC) ) 12.0 Hz, ipso C of
C6H3), 136.7 (s, ortho C of C6H3), 128.8 (s, meta C of C6H3),
126.5 (s, para C of C6H3), 39.4 (d, J (PC) ) 20.7 Hz, PCCH3),
31.0 (s, PCCH3), 26.1 (d, J (PC) ) 2.6 Hz, PCH2CH2), 24.6 (d,
J (RhC) ) 2.9 Hz, CH2CH3), 23.7 (br, CH2CH3), 21.4 (d, J (PC)
) 14.9 Hz, PCH2), 21.2 (s, C6H3(CH3)2). 31P NMR (81.0 MHz,
CD2Cl2, 293 K): δ 60.2 (d, J (RhP) ) 152.6 Hz). Anal. Calcd
for C40H72P2Cl4Rh2: C, 49.91; H, 7.54; Rh, 21.38. Found: C,
49.88; H, 7.29; Rh, 21.62.
P r ep a r a tion of [(η6-2,6-Me2C6H3CH2CH2P tBu 2-KP )Rh -
(C8H14)]P F 6 (20). A solution of 19 (505 mg, 0.86 mmol) in
acetone (3 mL) was treated dropwise with a solution of 3 (241
mg, 0.86 mmol) in acetone (5 mL), and the mixture was stirred
for 5 min at room temperature. After the solution was
concentrated to ca. 3 mL in vacuo, diethyl ether (10 mL) was
added. An orange solid precipitated, which was filtered,
washed three times with diethyl ether (5 mL each) and twice
with pentane (5 mL each), and dried. Yield: 516 mg (94%).
1
Mp: 58 °C dec. ΛΜ ) 101 cm2 Ω-1 mol-1. H NMR (400 MHz,
acetone-d6): δ 6.86 (m, 2 H, meta H of C6H3), 5.77 (m, 1 H,
para H of C6H3), 4.03 (m, 2 H, dCH of C8H14), 2.81 (m, 4 H,
PCH2 and PCH2CH2), 2.60 (s, 6 H, C6H3(CH3)2), 2.34, 1.80 (both
m, 2 H each, CH2 of C8H14), 1.66-1.35 (m, 8 H, CH2 of C8H14),
1.36 (d, J (PH) ) 13.5 Hz, 18 H, PCCH3). 13C NMR (100.6 MHz,
acetone-d6): δ 120.5 (s, ortho C of C6H3), 117.9 (dd, J (PC) )
5.1, J (RhC) ) 4.1 Hz, ipso C of C6H3), 112.2 (s, meta C of C6H3),
91.6 (dd, J (PC) ) 10.2, J (RhC) ) 3.1 Hz, para C of C6H3), 68.3
(d, J (RhC) ) 13.2 Hz, dCH of C8H14), 39.2 (dd, J (PC) ) 16.3,
J (RhC) ) 2.0 Hz, PCCH3), 38.7 (d, J (PC) ) 23.4 Hz, PCH2),
33.5, 32.7, 26.6 (all s, CH2 of C8H14), 30.5 (s, PCH2PCH2), 30.2
(d, J (PC) ) 3.0 Hz, PCCH3), 19.2 (s, C6H3(CH3)2). 31P NMR
(162.0 MHz, acetone-d6): δ 92.7 (d, J (RhP) ) 191.8 Hz, tBu2P),
-144.1 (sept, J (FP) ) 708.5 Hz, PF6). Anal. Calcd for
P r ep a r a tion of tr a n s-[Rh Cl(CO)(2,6-Me2C6H3CH2CH2-
P tBu 2-KP )2] (17). (a) A suspension of 16 (56 mg, 0.06 mmol)
in pentane (5 mL) was treated with a solution of 3 (36 mg,
0.13 mmol) in pentane (4 mL). After ca. 10 s a light yellow
solution was formed, which was concentrated to ca. 1 mL in
vacuo and then chromatographed on Al2O3 (neutral, activity
grade III, length of column 10 cm). First, with hexane a
colorless fraction was eluted, containing 3 and the correspond-
ing phosphine oxide. Second, with benzene a light yellow
fraction was eluted and brought to dryness in vacuo. The
remaining yellow solid was washed twice with pentane (5 mL
each) and dried. Yield: 83 mg (91%).
C
26H45F6P2Rh: C, 49.06; H, 7.13. Found: C, 49.50; H, 6.91.
P r ep a r a tion of [(η6-2,6-Me2C6H3CH2CH2P tBu 2-KP )Rh -
(C2H4)]P F 6 (21). A solution of 20 (202 mg, 0.32 mmol) in
dichloromethane (3 mL) was stirred under an atmosphere of
ethene at 75 °C for 1.5 h. After the heating bath was removed,
the volatile materials were removed in vacuo. The yellow
residue was washed with diethyl ether (10 mL) and dried. It
was dissolved in CH2Cl2 (3 mL), and the preparative procedure
(stirring under ethene at 75 °C for 1.5 h, removal of the
volatiles) was repeated four times. Finally, the residue was
dissolved in acetone (4 mL), the solution was filtered, and the
filtrate was concentrated to ca. 2 mL in vacuo. After diethyl
ether (10 mL) was added, an orange solid precipitated, which
was separated from the mother liquor, washed twice with
diethyl ether (5 mL each) and twice with pentane (5 mL each),
and dried. Yield: 156 mg (88%). Mp: 175 °C dec. ΛΜ 92 cm2
(b) 17 was obtained analogously as described for (a) from
15 (92 mg, 0.19 mmol) and 3 (54 mg, 0.19 mmol). Yield: 122
1
mg (87%). Mp: 188 °C dec. IR (CH2Cl2): ν(CO) 1937 cm-1. H
NMR (400 MHz, C6D6): δ 7.01 (m, 6 H, C6H3), 3.23 (m, 4 H,
PCH2CH2), 2.55 (s, 12 H, C6H3(CH3)2), 2.45 (m, 4 H, PCH2),
1.42 (vt, N ) 12.9 Hz, 36 H, PCCH3). 13C NMR (100.6 MHz,
C6D6): δ 190.8 (dt, J (RhC) ) 73.4, J (PC) ) 15.3 Hz, CO), 140.1
(vt, N ) 12.4 Hz, ipso C of C6H3), 136.9 (s, ortho C of C6H3),
129.1 (s, meta C of C6H3), 126.4 (s, para C of C6H3), 36.1 (vt,
N ) 15.3 Hz, PCCH3), 30.9 (m, PCCH3), 27.1 (s, PCH2CH2),
21.8 (s, C6H3(CH3)2), 20.4 (vt, N ) 13.4 Hz, PCH2). 31P NMR
(162.0 MHz, C6D6): δ 55.9 (d, J (RhP) ) 120.4 Hz). Anal. Calcd
for C37H62OP2ClRh: C, 61.45; H, 8.64. Found: C, 61.06; H,
8.71.
Ω-1 mol-1 1H NMR (400 MHz, acetone-d6): δ 7.08 (m, 2 H,
.
meta H of C6H3), 5.16 (m, 1 H, para H of C6H3), 3.25 (br s, 4
H, dCH2), 2.90-2.84 (m,4 H, PCH2 and PCH2PCH2), 2.63 (s,
6 H, C6H3(CH3)2), 1.30 (d, J (PH) ) 13.8 Hz, 18 H, PCCH3).
13C NMR (100.6 MHz, acetone-d6): δ 121.6 (d, J (RhC) ) 2.9
Hz, ortho C of C6H3), 120.5 (dd, J (RhC) ) 4.8, J (PC) ) 3.8 Hz,
ipso C of C6H3), 109.1 (s, meta C of C6H3), 89.4 (dd, J (PC) )
11.0, J (RhC) ) 3.3 Hz, para C of C6H3), 42.4 (d, J (RhC) ) 14.3
Hz, dCH2), 39.1 (d, J (PC) ) 23.8 Hz, PCH2), 38.7 (dd, J (PC)
) 17.2, J (RhC) ) 1.9 Hz, PCCH3), 30.3 (d, J (PC) ) 2.9 Hz,
PCCH3), 27.0 (s, PCH2CH2), 19.1 (s, C6H3(CH3)2). 31P NMR
(162.0 MHz, acetone-d6): δ 96.0 (d, J (RhP) ) 185.3 Hz, tBu2P),
-144.1 (sept, J (FP) ) 708.4 Hz, PF6). Anal. Calcd for
P r ep a r a tion of [Rh (µ-Cl)Cl(C2H5)(2,6-Me2C6H3CH2CH2-
P tBu 2-KP )]2 (18). A slow stream of gaseous HCl was passed
through a suspension of 9 (123 mg, 0.14 mmol) in dichlo-
romethane (3 mL) for 10 s at room temperature. An orange
solution was formed, from which the solvent was evaporated
in vacuo. The remaining orange solid was washed three times
with pentane (5 mL each) and dried. Yield: 112 mg (83%).
1
C
20H35F6P2Rh: C, 43.33; H, 6.36. Found: C, 42.86; H, 6.05.
Mp: 102 °C dec. H NMR (300 MHz, CD2Cl2, 293 K): δ 7.01
(m, 6 H, C6H3), 4.60 (br, 4 H, CH2CH3), 3.05 (br, 4 H,
PCH2CH2), 2.42 (s, 6 H, C6H3(CH3)2), 2.15 (br, 4 H, PCH2), 1.60
(d, J (PH) ) 13.2 Hz, 36 H, PCCH3), 1.14 (t, J (HH) ) 7.1 Hz,
6 H, CH2CH3). 1H NMR (200 MHz, CD2Cl2, 313 K): δ 7.02 (m,
6 H, C6H3), 4.63 (ddq, J (HH) ) 7.1, J (PH) ) J (RhH) ) 2.2 Hz,
4 H, CH2CH3), 3.11 (m, 4 H, PCH2CH2), 2.45 (s, 6 H, C6H3-
Gen er a tion of [Rh (H)2{OdC(CD3)2}3(2,6-Me2C6H3CH2-
CH2P tBu 2-KP )]P F 6 (22). A solution of 21 (41 mg, 0.07 mmol)
in acetone-d6 (0.5 mL) was stirred under a hydrogen atmo-
sphere (1 bar) for 12 h at room temperature. A gradual change
of color from orange to brown-yellow occurred. The solution
was then investigated by spectroscopic techniques. IR (acetone-

1150 Organometallics, Vol. 23, No. 5, 2004
Canepa et al.
d6): ν(RhH) 2127, 2067 (br) cm-1. 1H NMR (400 MHz, acetone-
d6): δ 6.99 (m, 3 H, C6H3), 3.02 (m, 2 H, PCH2CH2), 2.35 (s, 6
H, C6H3(CH3)2), 1.91 (m, 2 H, PCH2), 1.35 (d, J (PH) ) 12.6
Hz, 18 H, PCCH3), -23.40 (dd, J (RhH) ) J (PH) ) 27.9 Hz, 2
H, RhH). 13C NMR (100.6 MHz, acetone-d6): δ 211.5 (br s, Cd
O), 140.0 (d, J (PC) ) 13.4 Hz, ipso C of C6H3), 136.5 (s, ortho
C of C6H3), 129.1 (s, meta C of C6H3), 126.8 (s, para C of C6H3),
36.5 (d, J (PC) ) 23.8 Hz, PCCH3), 30.1 (d, J (PC) ) 2.9 Hz,
PCCH3), 28.6 (s, PCH2PCH2), 25.0 (d, J (PC) ) 24.8 Hz, PCH2),
20.5 (s, C6H3(CH3)2). 31P NMR (162.0 MHz, acetone-d6): δ 92.1
(br d, J (RhP) ) 165.7 Hz, tBu2P), -144.2 (sept, J (FP) ) 708.4
Hz, PF6).
P r epar ation of [(η6-2,6-Me2C6H3CH2CH2P tBu 2-KP )Rh H2]-
P F 6 (23). (a) A solution of 21 (263 mg, 0.47 mmol) in acetone
(6 mL) was stirred under a hydrogen atmosphere (1 bar) for
12 h at room temperature. A gradual change of color from
orange to brown-yellow occurred. The solution was concen-
trated to ca. 2 mL in vacuo and then layered with diethyl ether
(12 mL). After the mixture was stored for 6 h, a pale brown
solid precipitated, which was filtered, washed twice with
diethyl ether (5 mL each) and twice with pentane (5 mL each),
and dried. Yield: 224 mg (90%).
(b) A solution of 20 (101 mg, 0.16 mmol) in acetone (3 mL)
was stirred under a hydrogen atmosphere (1 bar) for 14 days
at room temperature. A smooth change of color from orange-
red to brown-yellow occurred, and a metallic-like solid pre-
cipitated. The solution was filtered, concentrated in vacuo to
ca. 1 mL, and then layered with diethyl ether (10 mL). After
the mixture was stored for 6 h, a pale-brown solid precipitated,
which was worked up as described for (a). Yield: 51 mg (61%).
Mp: 67 °C dec. ΛΜ ) 99 cm2 Ω-1 mol-1. IR (KBr): ν(RhH)
2127, 2067 cm-1. 1H NMR (400 MHz, CD2Cl2): δ 6.85 (m, 2 H,
meta H of C6H3), 6.21 (m, 1 H, para H of C6H3), 3.13-2.96 (m,
4 H, PCH2 and PCH2CH2), 2.52 (s, 6 H, C6H3(CH3)2), 1.25 (d,
J (PH) ) 15.3 Hz, 18 H, PCCH3), -12.51 (dd, J (RhH) ) 25.9,
J (PH) ) 19.9 Hz, 2 H, RhH). 13C NMR (100.6 MHz, CD2Cl2):
δ 132.0 (dd, J (PC) ) 5.7, J (RhC) ) 1.9 Hz, ipso C of C6H3),
121.3 (s, ortho C of C6H3), 109.4 (s, meta C of C6H3), 93.4 (dd,
J (PC) ) 6.7, J (RhC) ) 1.9 Hz, para C of C6H3), 40.2 (d, J (PC)
) 21.0 Hz, PCH2), 37.9 (dd, J (PC) ) 23.9, J (RhC) ) 1.9 Hz,
PCCH3), 28.9 (d, J (PC) ) 3.8 Hz, PCCH3), 27.3 (s, PCH2PCH2),
19.3 (s, C6H3(CH3)2). 31P NMR (162.0 MHz, CD2Cl2): δ 130.6
(d, J (RhP) ) 152.6 Hz, tBu2P), -144.4 (sept, J (FP) ) 710.6
Hz, PF6). Anal. Calcd for C18H33F6P2Rh: C, 40.92; H, 6.30.
Found: C, 40.59; H, 6.13.
Gen er a tion of [(η6-2,6-Me2C6H3CH2CH2P tBu 2-KP )Rh -
(OdCMe2)]P F 6 (24). A solution of 23 (43 mg, 0.08 mmol) in
acetone (2 mL) was stored for 4 weeks at room temperature.
A smooth change of color from light yellow to brown occurred.
The 31P NMR spectrum displayed a new resonance at δ 108.3
(d, J (RhP) ) 198.4 Hz), while the signal of 23 had disappeared.
Attempts to isolate the product failed or led to decomposition
of the material. Spectroscopic data for 24 are as follows. 1H
NMR (200 MHz, acetone-d6): δ 6.87 (m, 2 H, meta H of C6H3),
5.46 (m, 1 H, para H of C6H3), 2.42-2.28 (m, 4 H, PCH2 and
PCH2CH2), 2.38 (s, 6 H, C6H3(CH3)2), 1.36 (d, J (PH) ) 12.8
Hz, 18 H, PCCH3). 13C NMR (50.3 MHz, acetone-d6): δ 114.9
(d, J (PC) ) 6.5 Hz, ortho C of C6H3), 109.2 (d, J (RhC) ) 1.9
Hz, meta C of C6H3), 90.8 (dd, J (PC) ) 10.6, J (RhC) ) 3.3 Hz,
para C of C6H3), 85.5 (dd, J (PC) ) 8.3, J (RhC) ) 4.6 Hz, ipso
C of C6H3), 37.3 (d, J (PC) ) 17.6 Hz, PCCH3), 33.0 (d, J (PC)
) 24.0 Hz, PCH2), 29.2 (d, J (PC) ) 4.6 Hz, PCCH3), 27.6 (s,
PCH2CH2), 19.3 (s, C6H3(CH3)2). 31P NMR (81.0 MHz, acetone-
d6): δ 108.3 (d, J (RhP) ) 198.4 Hz, tBu2P), -142.7 (sept, J (FP)
) 707.0 Hz, PF6).
(2 mL), and the solution was chromatographed on Al2O3 (acidic,
activity grade III, length of column 4 cm). With CH2Cl2 a green-
yellow fraction was eluted, which was brought to dryness in
1
vacuo. The H and 31P NMR spectra showed that the residue
consisted of a mixture (ca. 1:1) of 14 and [nBu4N]PF6, which
could not be separated by either repeated chromatography or
fractional crystallization.
P r ep a r a tion of [(η6-2,6-Me2C6H3CH2CH2P tBu 2-K-P )Rh -
(CH2dCHtBu )]P F 6 (25). A solution of 23 (95 mg, 0.18 mmol)
in acetone (2 mL) was treated with 3,3-dimethyl-1-butene (93
µL, 0.72 mmol) and stirred for 15 min at room temperature.
After diethyl ether (15 mL) was added, a yellow solid precipi-
tated, which was filtered, washed twice with diethyl ether (5
mL each) and with pentane (5 mL), and dried. Yield: 86 mg
(78%). Mp: 110 °C dec. ΛΜ ) 93 cm2 Ω-1 mol-1. 1H NMR (300
MHz, CD2Cl2): δ 7.04, 6.44 (both m, 1 H each, meta H of C6H3),
5.27 (m, 1 H, para H of C6H3), 4.51 (dddd, J (HH) ) 13.6, 8.9,
J (PH) ) 4.7, J (RhH) ) 2.7 Hz, 1 H, dCHC(CH3)3), 3.18 (ddd,
J (HH) ) 13.6, 1.0, J (RhH) ) 2.1 Hz, 1 H, one H of dCH2 cis
to tBu), 2.93 (dddd, J (HH) ) 8.9, 1.0, J (PH) ) 2.6, J (RhH) )
1.0 Hz, 1 H, one H of dCH2 trans to tBu), 2.77-2.58 (m, 4 H,
PCH2 and PCH2CH2), 2.53, 2.52 (both s, 3 H each, C6H3(CH3)2),
1.41 (d, J (PH) ) 13.6 Hz, 9 H, PCCH3), 1.20 (d, J (PH) ) 13.4
Hz, 9 H, PCCH3), 1.02 (s, 9 H, dCHC(CH3)3). 13C NMR (75.4
MHz, CD2Cl2): δ 122.3, 119.5 (both d, J (RhC) ) 2.9 Hz, ortho
C of C6H3), 118.2 (dd, J (PC) ) 4.9, J (RhC) ) 3.8 Hz, ipso C of
C6H3), 108.9 (s, meta C of C6H3), 108.0 (dd, J (PC) ) 3.2, J (RhC)
) 1.9 Hz, meta C of C6H3), 89.3 (dd, J (PC) ) 10.6, J (RhC) )
2.9 Hz, para C of C6H3), 79.2 (d, J (RhC) ) 12.4 Hz, dCHC-
(CH3)3), 40.2 (dd, J (PC) ) 13.8, J (RhC) ) 2.2 Hz, PCCH3), 40.0
(d, J (RhC) ) 12.7 Hz, dCH2), 38.0 (dd, J (PC) ) 16.4, J (RhC)
) 2.2 Hz, PCCH3), 37.6 (d, J (PC) ) 23.6 Hz, PCH2), 35.2 (s,
dCHC(CH3)3), 30.8 (s, PCCH3), 30.7 (s, dCHC(CH3)3), 29.3 (d,
J (PC) ) 2.9 Hz, PCCH3), 26.7 (s, PCH2CH2), 19.4, 18.9 (both
s, C6H3(CH3)2). 31P NMR (81.0 MHz, acetone-d6): δ 93.7 (d,
J (RhP) ) 188.2 Hz, tBu2P), -142.7 (sept, J (FP) ) 707.0 Hz,
PF6). Anal. Calcd for C24H43F6P2Rh: C, 47.22; H, 7.10. Found:
C, 47.00; H, 7.00.
P r ep a r a tion of [(η6-2,6-Me2C6H3CH2CH2P tBu 2-KP )Rh -
(CH2dCHP h )]P F 6 (26). A solution of 23 (67 mg, 0.13 mmol)
in acetone (2 mL) was treated with styrene (73 µL, 0.63 mmol),
and the mixture was stirred for 2 min at room temperature.
A rapid change of color from light yellow to orange-red
occurred. The solution was concentrated to ca. 0.5 mL in vacuo
and then layered with diethyl ether (10 mL). An orange solid
precipitated, which was filtered, washed twice with diethyl
ether (5 mL each) and pentane (5 mL), and dried. Yield: 76
mg (95%). Mp: 156 °C dec. ΛΜ 77 cm2 Ω-1 mol-1 1H NMR
.
(400 MHz, acetone-d6): δ 7.41 (m, 2 H, ortho H of dCHC6H5),
7.35 (m, 1 H, meta H of C6H3), 7.32 (m, 2 H, meta H of d
CHC6H5), 7.21 (m, 1 H, para H of dCHC6H5), 5.39 (dddd,
J (HH) ) 12.8, 8.2, J (PH) ) 3.3, J (RhH) ) 2.7 Hz, 1 H,
dCHC6H5), 5.03 (m, 1 H, meta H of C6H3), 4.91 (m, 1 H, para
H of C6H3), 4.27 (ddd, J (HH) ) 12.8, 1.8, J (RhH) ) 2.1 Hz, 1
H, one H of dCH2 cis to tBu), 3.00 (dddd, J (HH) ) 8.2, 1.8,
J (PH) ) 3.7, J (RhH) ) 2.1 Hz, 1 H, one H of dCH2 trans to
tBu), 2.96-2.68 (m, 4 H, PCH2 and PCH2CH2), 2.52, 2.46 (both
s, 3 H each, C6H3(CH3)2), 1.56, 1.32 (both d, J (PH) ) 13.5 Hz,
9 H each, PCCH3). 13C NMR (100.6 MHz, acetone-d6): δ 145.1
(s, ipso C of dCHC6H5), 129.5, 127.6, 126.8 (all s, ortho, meta,
and para C of dCHC6H5), 121.6 (d, J (RhC) ) 2.9 Hz, ortho C
of C6H3), 120.1 (d, J (RhC) ) 1.9 Hz, ortho C of C6H3), 119.1
(dd, J (PC) ) 5.7, J (RhC) ) 3.8 Hz, ipso C of C6H3), 114.3 (dd,
J (PC) ) 2.9, J (RhC) ) 1.9 Hz, meta C of C6H3), 111.1 (s, meta
C of C6H3), 93.3 (dd, J (PC) ) 10.5, J (RhC) ) 3.9 Hz, para C of
C6H3), 63.1 (d, J (RhC) ) 12.4 Hz, dCHC6H5), 40.0 (dd, J (PC)
) 15.3, J (RhC) ) 2.9 Hz, PCCH3), 38.7 (d, J (PC) ) 23.8 Hz,
PCH2), 38.2 (dd, J (PC) ) 16.2, J (RhC) ) 1.9 Hz, PCCH3), 37.3
(d, J (RhC) ) 13.4 Hz, dCH2), 30.6 (d, J (PC) ) 3.8 Hz, PCCH3),
29.8 (d, J (PC) ) 2.8 Hz, PCCH3), 26.9 (s, PCH2CH2), 19.1, 18.8
(both s, C6H3(CH3)2). 31P NMR (162.0 MHz, acetone-d6): δ 94.2
Rea ction of Com p ou n d 23 w ith [n Bu 4N]Cl. A solution
of 23 (56 mg, 0.11 mmol) in acetone (2 mL) was stored for 4
weeks at room temperature. After the solution was cooled to
-78 °C, it was treated with [nBu4N]Cl (29 mg, 0.10 mmol) and
then warmed to room temperature. The solvent was evapo-
rated in vacuo, the residue was dissolved in dichloromethane

Rh(I) and Rh(III) Complexes with a Bulky Phosphine
Organometallics, Vol. 23, No. 5, 2004 1151
Ta ble 1. Cr ysta llogr a p h ic Da ta for 9, 15, a n d 18
9
15
20H31ClO2PRh
472.78
18
formula
fw
C
40H70Cl2P2Rh2
C
C40H72Cl4P2Rh2
962.54
889.62
cryst size, mm
cryst syst
0.30 × 0.20 × 0.20
0.35 × 0.16 × 0.16
0.18 × 0.15 × 0.10
triclinic
triclinic
monoclinic
space group
cell dimens determn
a, Å
P1h (No. 2)
P1h (No. 2)
P21/c (No. 14)
5357 rflns, 2.428° < θ < 28.183°
10.0093(6)
5000 rflns, 2.60° < θ < 25.00°
6959 rflns, 2.400° < θ < 28.140°
8.5713(17)
7.9221(4)
b, Å
8.5866(17)
8.6663(4)
15.4273(9)
c, Å
30.745(6)
16.9724(9)
14.0090(8)
R, deg
â, deg
γ, deg
V, Å3
Z
94.76(3)
94.61(3)
112.88(3)
2061.8(7)
90.0310(10)
90.6400(10)
11.7650(10)
1082.10(9)
90
92.7580(10)
90
2160.7(2)
2
2
2
d
calcd, g cm-3
1.433
1.451
1.479
temp, K
µ, mm-1
173(2)
1.034
173(2)
0.997
193(2)
1.112
scan method
æ
ω
ω
2θ(max), deg
total no. of rflns
50.00
6781
52.74
17545
52.74
28637
no. of unique rflns
no. of obsd rflns
6781 (R(int) ) 0.0000)
5948 (I > 2σ(I))
6781
4416 (R(int) ) 0.0183)
4309 (I > 2σ(I))
4416
4412 (R(int) ) 0.0370)
4084 (I > 2σ(I))
4412
no. of rflns used for refinement
no. of params refined
final R indices (I > 2σ(I))a
R indices (all data)a
resid electron density, e Å-3
455
234
226
R1 ) 0.0534, wR2 ) 0.1394
R1 ) 0.0587, wR2 ) 0.1420
2.000/-1.529
R1 ) 0.0210, wR2 ) 0.0542
R1 ) 0.0216, wR2 ) 0.0546
0.596/-0.342
R1 ) 0.0311, wR2 ) 0.0709
R1 ) 0.0349, wR2 ) 0.0726
0.635/-0.267
a
2
2
2
w-1 ) [σ2Fo + (0.0769P)2 + 6.5760P] (9), w-1 ) [σ2Fo + (0.0295P)2 + 0.4618P] (15), and w-1 ) [σ2Fo + (0.0334P)2 + 0.0181P] (18),
where P ) (Fo + 2Fc2)/3.
2
(d, J (RhP) ) 185.3 Hz, tBu2P), -144.1 (sept, J (FP) ) 708.4
Hz, PF6). Anal. Calcd for C26H39F6P2Rh: C, 49.53; H, 6.24.
Found: C, 49.24; H, 6.18.
filtered, washed with diethyl ether (10 mL) and pentane (10
mL), and dried. Yield: 87 mg (91%). Mp: 154 °C dec. ΛΜ
)
119 cm2 Ω-1 mol-1. IR (KBr): ν(CO) 2001 cm-1. H NMR (300
MHz, acetone-d6): δ 7.27 (m, 2 H, meta H of C6H3), 6.33 (m, 1
H, para H of C6H3), 3.20 (m, 2 H, PCH2), 2.95 (m, 2 H,
PCH2CH2), 2.61 (s, 6 H, C6H3(CH3)2), 1.37 (d, J (PH) ) 15.0
Hz, 18 H, PCCH3). 13C NMR (75.5 MHz, acetone-d6): δ 185.9
(dd, J (RhC) ) 91.1, J (PC) ) 15.7 Hz, CO), 126.5 (d, J (RhC) )
2.8 Hz, ortho C of C6H3), 121.8 (dd, J (PC) ) 5.8, J (RhC) ) 3.0
Hz, ipso C of C6H3), 109.9 (dd, J (PC) ) J (RhC) ) 1.9 Hz, meta
C of C6H3), 92.4 (dd, J (PC) ) 6.9, J (RhC) ) 3.2 Hz, para C of
C6H3), 39.6 (d, J (PC) ) 21.7 Hz, PCH2), 38.9 (dd, J (PC) ) 21.5,
J (RhC) ) 1.6 Hz, PCCH3), 29.1 (d, J (PC) ) 3.7 Hz, PCCH3),
27.7 (s, PCH2CH2), 19.4 (s, C6H3(CH3)2). 31P NMR (81.0 MHz,
acetone-d6): δ 120.9 (d, J (RhP) ) 167.9 Hz, tBu2P), -142.7
(sept, J (FP) ) 707.0 Hz, PF6). Anal. Calcd for C19H31F6OP2-
Rh: C, 41.17; H, 5.64. Found: C, 41.20; H, 5.41.
1
P r ep a r a tion of [(η6-2,6-Me2C6H3CH2CH2P tBu 2-KP )Rh -
(HCtCP h )]P F 6 (27). A solution of 23 (93 mg, 0.18 mmol) in
acetone (3 mL) was treated with phenylacetylene (0.5 mL, 4.90
mmol) at room temperature. A rapid change of color from light
yellow to orange-red occurred. The reaction mixture was
stirred for 4 h, which led to the precipitation of an orange solid
(probably polyphenylacetylene). The solution was filtered, the
filtrate was concentrated to ca. 1 mL in vacuo, and diethyl
ether (10 mL) was added. An orange-red solid precipitated,
which was filtered, washed twice with diethyl ether (5 mL
each) and twice with pentane (5 mL each), and dried. Yield:
106 mg (96%). Mp: 162 °C dec. ΛΜ ) 117 cm2 Ω-1 mol-1. IR
(CH2Cl2): ν(tCH) 3163, ν(CtC) 1827 cm-1 1H NMR (400
.
MHz, acetone-d6): δ 7.72 (m, 2 H, ortho H of tCC6H5), 7.56,
7.25 (both m, 1 H each, meta H of C6H3), 7.45-7.36 (m, 3 H,
meta and para H of tCC6H5), 5.81 (d, J (RhH) ) 3.8 Hz, 1 H,
tCH), 5.34 (m, 1 H, para H of C6H3), 3.04-2.92 (m, 4 H, PCH2
and PCH2CH2), 2.85, 2.71 (both s, 3 H each, C6H3(CH3)2), 1.37,
1.10 (both br d, J (PH) ) 13.8 Hz, 9 H each, PCCH3). 13C NMR
(100.6 MHz, acetone-d6): δ 133.2, 129.5, 129.2 (all s, ortho,
meta, and para C of tCC6H5), 127.7 (d, J (RhC) ) 1.9 Hz, ipso
C of tCC6H5), 122.5 (dd, J (PC) ) 4.8, J (RhC) ) 3.8 Hz, ipso
C of C6H3), 120.1, 119.4 (both s, ortho C of C6H3), 112.9, 110.5
(both s, meta C of C6H3), 96.8 (dd, J (PC) ) 12.4, J (RhC) ) 1.9
Hz, para C of C6H3), 79.8 (dd, J (RhC) ) 16.2, J (PC) ) 1.9 Hz,
CtCH), 67.1 (dd, J (RhC) ) 14.3, J (PC) ) 4.8 Hz, CtCH), 38.9
(br m, PCCH3), 38.8 (d, J (PC) ) 24.8 Hz, PCΗ2), 29.7, 29.2
(both br s, PCCH3), 27.6 (s, PCH2CH2), 19.6, 19.5 (both s, C6H3-
(CH3)2). 31P NMR (162.0 MHz, acetone-d6): δ 103.2 (d, J (RhP)
) 187.5 Hz, tBu2P), -144.1 (sept, J (FP) ) 708.4 Hz, PF6). Anal.
Calcd for C26H37F6P2Rh: C, 49.69; H, 5.93. Found: C, 49.59;
H, 5.84.
X-r a y Str u ctu r e Deter m in a tion of Com p ou n d s 9, 15,
a n d 18. Single crystals of 9 were grown from benzene at room
temperature, those of 15 from a saturated solution in pentane
at -10 °C under a CO atmosphere, and those of 18 from
dichloromethane at room temperature. Crystal data collection
parameters are summarized in Table 1. The data were
collected on an IPDS Stoe diffractometer (9) and a Bruker
Smart Apex diffractometer with a D8 goniometer (15 and 18)
using monochromated Mo KR radiation (λ ) 0.710 73 Å).
Intensity data were corrected by Lorentz and polarization
effects, and empirical absorption corrections were applied. The
structures of 9 and 18 were solved by direct methods and the
structure of 15 by the Patterson method (SHELXS-97).34
Atomic coordinates and anisotropic thermal parameters of non-
hydrogen atoms were refined by full-matrix least squares on
F2 (SHELXL-97).35 The positions of all hydrogen atoms were
calculated according to ideal geometry and refined using the
riding method, except for H1a, H1b, H2a, H2b, H3a, H3b, H4a,
P r ep a r a tion of [(η6-2,6-Me2C6H3CH2CH2P tBu 2-KP )Rh -
(CO)]P F 6 (28). A solution of 27 (108 mg, 0.17 mmol) in acetone
(120 mL) was irradiated for 3 days with a UV lamp. It was
then concentrated to ca. 3 mL in vacuo, and diethyl ether (15
mL) was added. A light yellow solid precipitated, which was
(34) Sheldrick, G. M. Acta Crystallogr., Sect. A 1990, 46, 467-473.
(35) Sheldrick, G. M. Program for Crystal Structure Refinement;
Universita¨t Go¨ttingen, Go¨ttingen, Germany, 1996.

1152 Organometallics, Vol. 23, No. 5, 2004
Canepa et al.
and H4b of 9, which were found in a differential Fourier
synthesis.
measurements), Dr. G. Lange and Mr. F. Dadrich (mass
spectra), and BASF AG for gifts of chemicals.
Ack n ow led gm en t . We thank the Deutsche For-
schungsgemeinschaft (Grant SFB 347) and the Fonds
der Chemischen Industrie for financial support. More-
over, we gratefully acknowledge support by Mrs. R.
Schedl and Mr. C. P. Kneis (elemental analyses and
DTA), Mrs. M.-L. Scha¨fer and Dr. W. Bertermann (NMR
Su p p or tin g In for m a tion Ava ila ble: Crystallographic
data for 9 and 15 as CIF files. This material is available
free of charge via the Internet at http://pubs.acs.org. For the
corresponding data for 18, see ref 5.
OM034348P