Organometallic rhodium complexes containing peralkylated arsino(phosphino)methanes as ligands

Article abstract of DOI:10.1021/om971085o

The peralkylated arsino(phosphino)methanes R₂AsCH₂PR₂ (R = iPr, Cy) reacted with [{(η⁴-C₈H₁₂)RhCl}₂] by cleavage of the chloro bridges to give the mononuclear compounds [RhCl-(η<

Full text of DOI:10.1021/om971085o

Organometallics 1998, 17, 2619-2627
2619
Or ga n om eta llic Rh od iu m Com p lexes Con ta in in g
P er a lk yla ted Ar sin o(p h osp h in o)m eth a n es a s Liga n d s
Helmut Werner,* Matthias Manger, Ulrich Schmidt, Matthias Laubender, and
Birgit Weberndo¨rfer
Institut fu¨r Anorganische Chemie, Universita¨t Wu¨rzburg, Am Hubland,
D-97074 Wu¨rzburg, Germany
Received December 10, 1997
The peralkylated arsino(phosphino)methanes R2AsCH2PR2 (R ) iPr, Cy) reacted with [{(η4-
C8H12)RhCl}2] by cleavage of the chloro bridges to give the mononuclear compounds [RhCl-
(η4-C8H12)(κ-P-R2PCH2AsR2)] (1, 2). In contrast, treatment of the dimeric cyclooctadiene
complex with the tBu-substituted derivative tBu2AsCH2PiPr2 afforded dinuclear [{Rh(η4-
C8H12)}{Rh(κ2-As,P-tBu2AsCH2PiPr2)}(µ-Cl)2] (3), the first example of a d8 transition-metal
compound containing a CH2-bridged As/P donor system as a chelating ligand. The X-ray
crystal structure of 3 has been determined. Cationic complexes [Rh(η4-C8H12)(κ2-As,P-
R2AsCH2PR′2)]PF6 (4a , 5a , 6a ) were obtained from [{(η4-C8H12)RhCl}2], R2AsCH2PR′2, and
MPF6 (M ) K, Ag). The corresponding BPh4 salts (4b, 5b, 6b) were prepared from the PF6
salts upon metathesis with NaBPh4. The chelate compounds 4-6 reacted with CH2N2 by
insertion of CH2 into the Rh-As bond to yield the complexes [Rh(η4-C8H12)(κ2-C,P-CH2As-
(R)2CH2PR′2)]PF6 (7-9), which contain a five-membered metallacycle adopting an envelope
conformation in the crystal. The reaction of the BPh4 salts 4b and 5b with H2 gave the
half-sandwich-type complexes [(η6-C6H5BPh3)Rh(κ2-As,P-R2AsCH2PR′2)] (10, 11), in which
the tetraphenylborate is coordinated like a substituted arene to the metal center. Treatment
of the PF6 salt 6a with H2 in the presence of CF3CO2H led to the formation of the unusual
dinuclear hydrido-bridged complex [{RhH(κ2-As,P-Cy2AsCH2PCy2)}2(µ-H)(µ-O2CCF3)2]PF6
(12).
In tr od u ction
in nature, they mainly reflect the unequal σ-donor and
π-acceptor capabilities of trialkylphosphine and -arsine
or -stibine ligands.
There have been but few comparative studies con-
cerning the reactivity of homologous tertiary phosphine,
arsine, and stibine transition-metal complexes to date.1
Recent work in our laboratory has shown that the
replacement of PiPr3 by its higher homologues SbiPr3
and AsiPr3 or by the functionalized arsine iPr2As(CH2)2-
OMe as a ligand leads to remarkable differences in the
reactivity of low-valent metal complexes of the iron and
cobalt triad.2-4 Moreover, in almost all cases which
have been studied to date, the M-EiPr3 (E ) Sb, As)
bond is more labile than its M-PiPr3 counterpart, and
this can be put to advantage for synthetic purposes.2,4b,5
Although some of these differences are probably steric
To combine the favorable parts of the ligand behavior
of bulky trialkylphosphines on one side and of related
trialkylstibines or -arsines on the other, we set out to
prepare mixed (possibly hemilabile) P/E donor systems
(E ) Sb, As). Very recently, we reported the synthesis
of the first representatives of ligands of the type
R2PCH2SbR′2 with bulky alkyl or cycloalkyl groups R
and R′ and the application of the unsymmetrical ligands
in preparing organometallic rhodium complexes.6 Here
we describe some similarities as well as some remark-
able differences in the behavior of the corresponding
arsine derivatives R2AsCH2PR′2 in the coordination
sphere of rhodium as the metal center.
(1) (a) McAuliffe, C. A. Transition Metal Complexes of Phosphorus,
Arsenic and Antimony; Wiley: New York, 1973. (b) Levason, W.;
McAuliffe, C. A. Phosphine, Arsine and Stibine Complexes of the
Transition Elements; Elsevier: Amsterdam, 1977.
Resu lts a n d Discu ssion
(2) M ) Rh: (a) Schwab, P.; Mahr, N.; Wolf, J .; Werner, H. Angew.
Chem. 1993, 105, 1498-1500; Angew. Chem., Int. Ed. Engl. 1993, 32,
1480-1482. (b) Schwab, P.; Mahr, N.; Wolf, J .; Werner, H. Angew.
Chem. 1994, 106, 82-84; Angew. Chem., Int. Ed. Engl. 1994, 33, 97-
99. (c) Schwab, P.; Werner, H. J . Chem. Soc., Dalton Trans. 1994,
3415-3425. (d) Werner, H.; Heinemann, A.; Windmu¨ller, B.; Steinert,
P. Chem. Ber. 1996, 129, 903-910. (e) Werner, H.; Schwab, P.; Bleuel,
E.; Mahr, N.; Steinert, P. Chem. Eur. J . 1997, 3, 1375-1384.
(3) M ) Ir: Werner, H.; Ortmann, D.; Gevert, O. Chem. Ber. 1996,
129, 411-417.
(4) M ) Ru: (a) Werner, H.; Gru¨nwald, C.; Laubender, M.; Gevert,
O. Chem. Ber. 1996, 129, 1191-1194. (b) Braun, T.; Laubender, M.;
Gevert, O.; Werner, H. Chem. Ber. 1997, 130, 559-564. (c) Gru¨nwald,
C.; Laubender, M.; Wolf, J .; Werner, H. J . Chem. Soc., Dalton Trans.
1998, 833-839.
1. R ea ct ion of [{(η4-C8H 12)R h Cl}2] w it h R 2As-
CH2P R′2. According to the reactivity of bulky phos-
phino(stibino)methanes,6 the reactions of [{(η4-
C8H12)RhCl}2] with 2 equiv of the symmetrically sub-
(5) (a) Schwab, P. Dissertation, Universita¨t Wu¨rzburg, 1994. (b)
Heinemann, A. Dissertation, Universita¨t Wu¨rzburg, in preparation.
(c) Ortman, D.; Gru¨nwald, C.; Bleuel, E.; Herber, U. Unpublished
results. (d) Werner, H. J . Organomet. Chem. 1995, 500, 331-336.
(6) Manger, M.; Wolf, J .; Laubender, M.; Teichert, M.; Stalke, D.;
Werner, H. Chem. Eur. J . 1997, 3, 1442-1450.
S0276-7333(97)01085-6 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 05/13/1998

2620 Organometallics, Vol. 17, No. 12, 1998
Werner et al.
Sch em e 1
Sch em e 2
stituted ligands R2AsCH2PR2 (R ) iPr, Cy)7 in CH2Cl2/
ether or pentane at room temperature involve a facile
cleavage of the chloro bridges by the P-donor site of the
substrate but no replacement of the cyclooctadiene or
chloro ligands. The resulting neutral compounds 1 and
2 (Scheme 1) form yellow, moderately air-stable solids
that decompose between 50 and 60 °C.
F igu r e 1. Molecular structure (ORTEP plot) of compound
3.
rated by chromatographic techniques. However, drop-
wise treatment of a suspension of [{(η4-C8H12)RhCl}2]
with exactly 1 equiv of the ligand in hexane at room
temperature affords a different result. Removal of the
solvent and recrystallization of the crude product from
acetone yields an orange-red microcrystalline solid that
is thermally quite stable and readily soluble in CH2Cl2
or nonpolar solvents such as benzene and ether. In
comparison to those of 1 and 2, the signal of the 31P
nuclei in the 31P NMR spectrum of 3 appears unexpect-
edly at higher field, and the 103Rh-31P coupling constant
increases from ca. 144 Hz to 172.0 Hz. A similar value
results for the dinuclear complex [{(κ2-P,P-tBu2-
PCH2PtBu2)Rh}2(µ-Cl)2], which is formed upon treat-
ment of [{(C8H14)2RhCl}2] with 2 equiv of tBu2-
PCH2PtBu2.10 The 1H and 13C NMR spectra of 3 (which
in contrast to those of 1 and 2 show no temperature
dependence) confirm that one C8H12 ligand is still
present. Since the chemical shift of the proton and the
carbon signals for the bridging AsCH2P unit are in
agreement with a chelating coordination mode of the
arsino(phosphino)methane ligand, we conclude that
from [{(η4-C8H12)RhCl}2] and tBu2AsCH2PiPr2 a di-
nuclear complex is formed by substitution of one of the
diolefin ligands in the starting material (Scheme 2).
To obtain information about the detailed structural
aspects of 3 (which is the first structurally characterized
transition-metal complex containing an arsino(phos-
phino)methane as a chelating ligand), an X-ray crystal
structure investigation was carried out. The ORTEP
diagram (Figure 1) reveals that both metal centers are
coordinated in a square-planar fashion. The angle
between the two planes [Cl1, Rh1, Cl2] and [Cl1, Rh2,
Cl2] is 116.9(7)° and is thus slightly smaller (ca. 6°) than
in the related compound [{Rh(η4-C8H12)}{Rh-
[P(OC6H5)3]2}(µ-Cl)2].11 We note that the central Rh(µ-
Cl)2Rh unit of the starting material [{(η4-C8H12)RhCl}2]
is strictly planar.12 In contrast to the mononuclear
cationic complex [Rh(η4-C8H12)(κ2-P,Sb-iPr2PCH2-
SbtBu2)]+, where the RhPCSb fragment is planar,6 the
Although the 31P NMR spectra of 1 and 2 display a
sharp doublet at δ 32.6 (for 1) and 25.2 (for 2) with a
103Rh-31P coupling constant of ca. 144 Hz, which
corresponds to the data found for the structurally
related complexes [RhCl(η4-C8H12)(PR3)]8 and also for
the stibine derivatives [RhCl(η4-C8H12)(κ-P-R2PCH2-
SbR′2)],6 the 1H NMR spectra of 1 and 2 differ from those
of the latter. Instead of two sets of signals for the
chemically nonequivalent protons of the -CHdCH-
double bonds of the cyclooctadiene unit, the 1H NMR
spectra of 1 and 2 display only one broadened signal at
δ 4.6-4.7, which we attribute to an intermolecular
exchange process at room temperature. At lower tem-
peratures, this dynamic behavior is slowed and two
broadened signals appear at the supposed chemical shift
(δ 5.60 and 3.50). A similar situation is found in
complexes of the type [MCl(diene)L] (M ) Rh, Ir; L )
AsPh3, SbPh3; diene ) η4-C8H12, η4-norbornadiene).9
Owing to the monodentate coordination mode of the
arsino(phosphino)methanes, the signal of the bridging
AsCH2P carbon atom in the 13C NMR spectrum of 1
exhibits a slight upfield shift of about 1.7 ppm compared
to that of iPr2AsCH2PiPr2 (δ 11.6), while at the same
1
time the J (PC) coupling constant decreases from 31.4
to 12.2 Hz.
In contrast to the reaction of [{(η4-C8H12)RhCl}2] with
iPr2PCH2AsiPr2 and Cy2PCH2AsCy2 leading to the
formation of 1 and 2, treatment of the same organo-
7
metallic precursor with 2 equiv of tBu2AsCH2PiPr2
gives a mixture of products, which could not be sepa-
(7) The arsino(phosphino)methanes have been prepared in the same
way as the corresponding phosphino(stibino)methanes.6
(8) (a) Chatt, J .; Venanzi, L. M. J . Chem. Soc. (A) 1957, 4735-4741.
(b) Fougeroux, P.; Denise, B.; Bonnaire, R. J . Organomet. Chem. 1973,
60, 375-386. (c) Crabtree, R. H.; Gautier, A.; Giordano, G.; Kahn, T.
J . Organomet. Chem. 1977, 141, 113-121. (d) Murray, B. D.; Hope,
H.; Hvoslef, J .; Power, P. P. Organometallics 1984, 3, 657-663. (e)
Iglesias, M.; del Pino, C.; Corma, A.; Garcia-Blanco, S. Inorg. Chim.
Acta 1987, 127, 215-221.
(9) (a) Vrieze, K.; Volger, H. C.; Pratt, A. P. J . Organomet. Chem.
1968, 14, 185-200. (b) Vrieze, K.; Volger, H. C.; Pratt, A. P. J .
Organomet. Chem. 1968, 15, 195-208. (c) Vrieze, K.; van Leeuwen, P.
W. N. M. Prog. Inorg. Chem. 1971, 14, 1-63. (d) Crabtree, R. H.;
Morris, G. E. J . Organomet. Chem. 1977, 135, 395-403.
(10) (a) Hofmann, P.; Meier, C.; Englert, U.; Schmidt, M. U. Chem.
Ber. 1992, 125, 353-365. (b) Hofmann, P.; Meier, C.; Hiller, W.; Heckel,
M.; Riede, J .; Schmidt, M. U. J . Organomet. Chem. 1995, 490, 51-70.
(11) Coetzer, J .; Gafner, G. Acta Crystallogr. 1970, B26, 985-990.
(12) Ibers, J . A.; Snyder, R. G. Acta Crystallogr. 1962, 15, 923-930.

Organometallic Rhodium Complexes
Organometallics, Vol. 17, No. 12, 1998 2621
Ta ble 1. Selected Bon d Dista n ces a n d An gles
w ith Esd ’s for Com p ou n d 3
Sch em e 3
Bond Distances (Å)
Rh2-As
Rh2-P
Rh2-Cl1
Rh2-Cl2
Rh1-Cl1
Rh1-Cl2
2.306(2)
2.187(2)
2.441(2)
2.401(3)
2.389(3)
2.391(2)
Rh1-C1
Rh1-C2
Rh1-C5
Rh1-C6
As-C9
2.116(8)
2.098(8)
2.101(8)
2.105(9)
1.958(8)
1.851(9)
P-C9
Bond Angles (deg)
Cl1-Rh1-Cl2
Cl1-Rh2-Cl2
Rh1-Cl1-Rh2
Rh1-Cl2-Rh2
Cl1-Rh2-As
85.47(8)
84.12(9)
77.62(7)
78.35(6)
99.55(8)
Cl2-Rh2-P
Rh2-As-C9
As-Rh2-P
Rh2-P-C9
P-C9-As
101.37(9)
93.0(3)
74.90(8)
100.0(3)
91.7(4)
RhAsCP four-membered ring of 3 is somewhat bent, the
dihedral angle being 6.6(7)°. The As-Rh-P bite angle
(74.90(8)°) is relatively small and comparable to the bite
angle of [Rh(η4-C8H12)(κ2-P,Sb-iPr2PCH2SbtBu2)]+ and
to that of neutral rhodium(I) compounds with tBu2-
PCH2PtBu2 as chelating ligand.10 The Rh-As distance
of 3 is 2.306(2) Å (see Table 1) and therefore signifi-
cantly shorter than the Rh-As bond length in trans-
[RhCl(η2-CH2dCdCH2)(AsiPr3)2] (average value 2.43
Å).13 The Rh-P distance of 2.187(2) Å is comparable to
that of chloro-bridged rhodium(I) complexes with mono-
or bidentate phosphine ligands;10,11 however, it is shorter
than the Rh-P bond length in [Rh(η4-C8H12)(κ2-P,Sb-
iPr2PCH2SbtBu2)]+ (2.317(1) Å).6 The distances be-
tween the two rhodium centers and the bridging chlo-
rides as well as those between Rh1 and the sp2 carbon
atoms of the diolefin fall into the expected range and
thus deserve no further comment.
Sch em e 4
One notable structural feature is the Rh1-Rh2
distance of 3.028(1) Å. It is not only shorter than in
the bent complex [{(κ2-P,P-tBu2PCH2PtBu2)Rh}2(µ-Cl)2]
(ca. 3.27 Å)10 but also shorter than in the unsymmetrical
complex [{Rh(η4-C8H12)}{Rh[P(OC6H5)3]2}(µ-Cl)2] (3.138-
(2) Å)11 mentioned above. Although the oxidation
number of Rh in 3 is undoubtedly +1, we think that in
agreement with the structural data found for other
dinuclear rhodium(I) compounds14 a weak interaction
between the two metal centers of 3 can be taken into
consideration.
final product.15 Compounds 4a -6a are orange-red and
4b-6b orange-yellow solids that are air-stable and
readily soluble in polar solvents. The most significant
difference between the spectroscopic data of 4-6 and
those of 1 and 2 is the downfield shift of the signals of
1
the AsCH2P unit in the H and 13C NMR and the high-
2. Ca tion ic (Cycloocta d ien e)r h od iu m (I) Com -
p lexes Con ta in in g Ar sin o(p h osp h in o)m eth a n es a s
Liga n d s. The reactions of [{(η4-C8H12)RhCl}2] with
R2AsCH2PR2 (R ) iPr, Cy) or tBu2AsCH2PiPr2 in the
presence of KPF6 or AgPF6 afford the cationic complexes
4a -6a in 60-75% yield. The corresponding BPh4 salts
4b-6b are obtained on treatment of the PF6 salts with
an excess of NaBPh4 in methanol (Scheme 3). The easy
formation of 4-6 is noteworthy insofar as related
chelate complexes of the general composition [Rh(η4-
C8H12)(κ2-P,P-R2PCH2PR2)]X have not yet been isolated.
For R ) Ph, such a species is presumably generated as
an intermediate on treatment of [{(η4-C8H12)RhCl}2]
with dppm, but it reacts quite rapidly with a second
molecule of Ph2PCH2PPh2 to give [Rh(dppm)2]Cl as the
field shift of the PR2 nuclei in the 31P NMR spectra.
These features are in close analogy to those of the
corresponding stibine complexes [Rh(η4-C8H12)(κ2-P,Sb-
R2PCH2SbR′2)]X.6 Moreover, the 1H and 13C NMR
spectra of 4-6 display two sets of signals for the protons
and the carbon atoms of the -CHdCH- double bonds
of the cyclooctadiene ligand, as is anticipated if two
different donor atoms in trans disposition to the double
bond are coordinated to the rhodium center.
The reactions of the compounds 4a -6a and 5b with
diazomethane in CH2Cl2 at low temperature proceed
with elimination of N2 and insertion of the remaining
CH2 unit into the supposedly labile Rh-As bond. The
resulting As-ylide complexes 7a , 8a ,b, and 9, which are
isolated in 80-95% yield, form yellow, moderately air-
stable solids that decompose with the exception of 7a
at 100-130 °C. The corresponding BPh4 salt 7b is
prepared from the PF6 salt 7a via anion exchange with
(13) Werner, H.; Schwab, P.; Mahr, N.; Wolf, J . Chem. Ber. 1992,
125, 2641-2650.
(14) (a) Drews, M. G. B.; Nelson, S. M.; Sloan, M. J . Chem. Soc.,
Dalton Trans. 1973, 1484-1489. (b) Bonnet, J . J .; J eannin, Y.; Kalck,
P.; Maisonnat, A.; Poilblanc, R. Inorg. Chem. 1975, 14, 743-747. (c)
Bonnet, J . J .; Kalck, P.; Poilblanc, R. Inorg. Chem. 1977, 16, 1514-
1518.
(15) Ernsting, J . M.; Elsevier, C. J .; de Lange, W. G.; Timmer, K.
Magn. Reson. Chem. 1991, 29, 118-124.

2622 Organometallics, Vol. 17, No. 12, 1998
Werner et al.
Sch em e 5
F igu r e 2. Molecular structure (ORTEP plot) of compound
7b.
Ta ble 2. Selected Bon d Dista n ces a n d An gles
w ith Esd ’s for Com p ou n d 7b
angle As-C9-P (108.0(3)°) is slightly larger by 2.3°
than in [Cr(CO)4{κ2-C,As-CH2As(Ph)2CH2AsPh2}].17 The
Rh-P bond length of 7b (2.312(2) Å) is almost identical
with that of other cationic square-planar (cycloocta-
diene)rhodium(I) complexes with bidentate phosphines
as ligands;18 it is, however, significantly shorter than
in the cationic (ylide)rhodium(III) complex [{(η5-
C5Me5)RhI{κ2-C,P-CH2P(Me)2CH2CH2PMe2}]+ (2.259(2)
Å).19 In contrast, the Rh-C10 distance (2.111(7) Å) is
comparable to that of the respective half-sandwich
complex (2.121(5) Å)19 and to that of the related cation
[{(η5-C5H5)Rh(κ-C-CH2PiPr3)(CH3)(CO)]+ (2.126(7) Å).16
In analogy to the reactivity of complexes of the type
[Rh(η4-C8H12)(PR3)2]X,20 the cyclooctadiene ligand of the
cationic derivatives [Rh(η4-C8H12)(κ2-As,P-R2AsCH2-
PR′2)]X can easily be replaced on treatment with H2 in
CH2Cl2 at room temperature. The reaction of the
resulting, probably solvated hydridorhodium(III) inter-
mediate depends on the type of the corresponding anion
X- and on the reaction conditions in particular. While
treatment of the BPh4 salts 4b and 5b with H2 leads to
the formation of the neutral half-sandwich type com-
Bond Distances (Å)
Rh-C10
Rh-P
As-C10
2.111(7)
2.312(2)
1.880(7)
As-C9
P-C9
1.915(7)
1.846(7)
Bond Angles (deg)
Rh-C10-As
P-Rh-C10
C9-P-Rh
109.9(3)
87.7(2)
110.4(2)
As-C9-P
C10-As-C9
108.0(3)
102.5(3)
NaBPh4 (Scheme 4). In analogy to the spectroscopic
data of the Sb-ylide complexes [Rh(η4-C8H12)(κ2-C,P-
CH2Sb(R′2)CH2PR2)]X,6 the 13C NMR spectra of 7-9
display a resonance for the carbon atom linked to
rhodium at δ ∼ 8.0, which is split into a doublet of
1
doublets owing to Rh-C and P-C coupling. In the H
NMR spectra of 7-9, the signals of the corresponding
methylene protons appear at δ ∼ 1.0 and thus at
somewhat higher field than for neutral rhodium(I)
compounds with CH2PiPr3 as ligand.16 According to the
different stereoelectronic features resulting from the
ring expansion of a four-membered chelate ring in 4-6
to a five-membered ring in 7-9, the 31P NMR spectra
of the latter exhibit a doublet which is shifted downfield
by ca. 54 ppm compared to that of 4-6. Moreover, the
103Rh-31P coupling constant increases from ca. 144 Hz
to ca. 161 Hz for the chelate complexes 7-9.
-
pounds 10 and 11 in excellent yield, for X- ) PF6
complete decomposition occurs in the absence of any
substrate. However, the reaction of 6a with H2 in the
presence of a slight excess of CF3CO2H gives the
unusual dinuclear hydrido-bridged rhodium(III) com-
plex 12 that can be isolated as a light yellow, almost
air-stable solid in about 75% yield (Scheme 5).
The most significant difference between the spectro-
scopic data of 10 (light red solid) and 11 (orange-yellow
solid) and those of 4b and 5b is the high-field shift of
The result of the X-ray crystal structure analysis of
7b is shown in Figure 2. The most notable feature is
that the five-membered chelate ring adopts an envelope
conformation that leads to a dihedral angle of 47.50(3)°
between the two planes [C10, Rh, P, C9] and [C10, As,
C9]. The P-Rh-C10 bite angle [87.7(2)°] (see Table 2)
is virtually the same as the As1-Cr-C6 bite angle of
the structurally related chromium complex [Cr(CO)4{κ2-
C,As-CH2As(Ph)2CH2AsPh2}] (88.1(1)°), which has been
prepared by Weber et al. from [Cr(CO)5{κ-C-
CH2S(O)Me2}] and Ph2AsCH2AsPh2.l7 In comparison to
the angle Cr-C6-As2 of this chromium compound
(113.6(2)°), the corresponding angle Rh-C10-As of 7b
is somewhat smaller (109.9(3)°), while the intraligand
(17) Weber, L.; Wewers, D.; Meyer, W.; Boese, R. Chem. Ber. 1984,
117, 732-742.
(18) See for example: (a) Ball, R. G.; Payne, N. C. Inorg. Chem. 1977,
16, 1187-1191. (b) Anderson, M. P.; Pignolet, L. H. Inorg. Chem. 1981,
20, 4101-4107. (c) Burk, M. J .; Feaster, J . E.; Harlow, R. L. Organo-
metallics 1990, 9, 2653-2655. (d) Marinetti, A.; Le Menn, C.; Ricard,
L. Organometallics 1995, 14, 4983-4985.
(19) Werner, H.; Hofmann, L.; Paul, W.; Schubert, U. Organo-
metallics 1988, 7, 1106-1111.
(20) (a) Schrock, R. R.; Osborn, J . A. J . Am. Chem. Soc. 1971, 93,
2397-2407. (b) Haines, L. M.; Singleton, E. J . Chem. Soc., Dalton
Trans. 1972, 1891-1896. (c) Crabtree, R. H. Acc. Chem. Res. 1979,
12, 331-338.
(16) Werner, H.; Schippel, O.; Wolf, J .; Schulz, M. J . Organomet.
Chem. 1991, 417, 149-162.

Organometallic Rhodium Complexes
Organometallics, Vol. 17, No. 12, 1998 2623
the resonance of the protons and the carbon atoms of
one phenyl group of the BPh4 anion. This feature is also
typical for related compounds of the general composition
[(η6-C6H5BPh3)RhL2] with L2 ) {P(OR)3}2,21 R2PCH2-
dinuclear complex 3 thus formed is one of the rare
examples in which the coordination sphere around the
central Rh2Cl2 core is completed by two different chelat-
ing ligands.
SbR′2,6 or R2PCH2CH2PR2 and clearly indicates that
22
With regard to the chemistry of the readily available
mononuclear complexes [Rh(η4-C8H12)(κ2-As,P-R2AsCH2-
PR′2)]X (4-6), it is in particular worth mentioning that
they react with diazomethane by insertion of CH2 into
the Rh-As bond. This observation strongly supports
the assumption that in a M(κ2-As,P-R2As-X-PR′2) chelate
the M-As linkage is more labile than the M-P counter-
part. Finally we note that on treatment of the cations
[Rh(η4-C8H12)(κ2-As,P-R2AsCH2PR′2)]+ with hydrogen
the cyclooctadiene is easily replaced and, if BPh4 is the
corresponding anion, the neutral half-sandwich type
compounds 10 and 11 are generated. The more spec-
tacular result, however, is the formation of the triply
bridged dinuclear complex 12 in which one hydrido and
two trifluoracetato ligands connect the two metal cen-
ters.
one ring is coordinated to rhodium. Moreover, the
change from a 16-electron metal center in 4b and 5b to
an 18-electron metal center in 10 and 11 results in a
downfield shift of the signal of the PR′2 nuclei in the
31P NMR spectra by ca. 17 ppm, whereas the 103Rh-
31P coupling constant increases from 125 to 129 to ca.
170-173 Hz. Similar values are found for the corre-
sponding complexes containing a phosphino(stibino)-
methane as ligand6 and also for the cyclopentadienyl
compound [(η5-C5H5)Rh(κ2-P,P-Ph2PCH2PPh2)].23
Despite a closed (18-electron) valence shell for each
rhodium due to the three-center-two-electron bond
between the two metal centers and the bridging hydrido
ligand, the 103Rh-31P coupling constant in the 31P NMR
spectrum of 12 (111.2 Hz) is quite small compared with
that of the starting material 6a . This indicates that the
oxidation state of the rhodium has changed from +1 to
+3. In the 1H NMR spectrum of 12, the signal assigned
to the bridging hydrido ligand appears at δ -17.52 and
is split into a triplet of triplets due to coupling with two
equivalent 103Rh and two equivalent 31P nuclei. The
large 103Rh-1H coupling constant of 25.0 Hz seems to
be typical for a bridging RhHRh moiety.24 The chemical
shift of the signal assigned to the PCH2As carbon atom
in the 13C NMR spectrum of 12, which is almost
identical with that of the starting material 6a , leaves
no doubt that the coordination mode of the arsino-
(phosphino)methane is unchanged. We note that with
bulky phosphino(stibino)methanes iPr2PCH2SbR′2 as
ligands similar dinuclear rhodium complexes of compo-
sition [{RhH(κ2-P,Sb-iPr2PCH2SbR′2)}2(µ-H)(µ-O2CCF3)2]-
PF6 have recently been obtained, one of which (with R′
) tBu) has been characterized by X-ray crystal structure
analysis.25
Exp er im en ta l Section
Gen er a l Con sid er a tion s. All experiments were carried
out under an atmosphere of argon by Schlenk techniques.
Solvents were dried by known procedures and distilled before
use. The starting materials R2AsCH2PiPr2 (R ) iPr, tBu),7
Cy2AsCH2PCy2,7 and [{(η4-C8H12)RhCl}2]26 were prepared as
described in the literature.
P h ysica l Mea su r em en ts. NMR spectra were recorded at
room temperature or at the temperature mentioned in the
appropriate procedure on Bruker AC 200 and Bruker AMX
400 instruments. Chemical shifts are expressed in ppm
downfield from SiMe4 (1H and 13C) and (85%) H3PO4 (31P).
Abbreviations used: s, singlet; d, doublet; q, quartet; sept,
septet; m, multiplet; br, broadened signal. Coupling constants
J are given in hertz. Melting points were measured by DTA.
For the assignment of HA and HB see procedure for the
preparation of compound 4a (Figure 3).
P r ep a r a tion of [Rh Cl(η4-C8H12)(K-P -iP r 2P CH2AsiP r 2)]
(1). A solution of [{(η4-C8H12)RhCl}2] (113 mg, 0.23 mmol) in
CH2Cl2 (4 mL) was treated with a solution of iPr2AsCH2PiPr2
(135 mg, 0.46 mmol) in ether (3 mL) and stirred for 1 h at
room temperature. The solvent was removed, the oily residue
was suspended in ether (4 mL), and the suspension was stirred
for 10 min. After removal of the solvent, the procedure was
repeated twice and the remaining solid was washed with ether
(4 mL). The solid was dissolved in acetone (5 mL), and the
solution was stored at -60 °C for 12 h. Yellow crystals were
obtained which were separated from the mother liquor and
dried: yield 53 mg (21%); mp 51 °C dec. 1H NMR (400 MHz,
C6D6): δ 4.64 (br s, 4H, dCH of C8H12), 2.50 (m, 2H, PCHCH3),
2.22 (br m, 4H, CH2 of C8H12), 2.00 [sept, J (HH) ) 7.2 Hz, 2H,
AsCHCH3], 1.75 (br m, 4H, CH2 of C8H12), 1.58 [d, J (PH) )
7.6 Hz, 2H, AsCH2P], 1.33, 1.27 [both dd, J (PH) ) 14.2, J (HH)
) 7.2 Hz, 12H, PCHCH3], 1.12, 1.10 [both d, J (HH) ) 7.2 Hz,
12H, AsCHCH3]. 13C NMR (100.6 MHz, C6D6): δ 86.0 (br s,
dCH of C8H12), 31.2 (br s, CH2 of C8H12), 25.3 [d, J (PC) ) 21.2
Hz, PCHCH3], 25.0 [d, J (PC) ) 3.5 Hz, AsCHCH3], 21.5 (s,
AsCHCH3), 20.1 (br s, PCHCH3), 19.5 (s, AsCHCH3), 9.9 [d,
J (PC) ) 12.2 Hz, AsCH2P]. 31P NMR (162.0 MHz, C6D6): δ
32.6 [d, J (RhP) ) 144.8 Hz]. Anal. Calcd for C21H42AsClPRh
(538.8): C, 46.81; H, 7.85. Found: C, 46.99; H, 7.75.
Con clu sion s
The work presented in this paper has shown that
phosphino(arsino)methanes R2AsCH2PR′2 with bulky
alkyl or cycloalkyl groups R and R′, which are accessible
from Ph3SnCH2PR′2 via LiCH2PR′2 as intermediates,7
behave as monodentate (P-bonded) as well as bidentate
ligands toward rhodium. One of the most remarkable
features is that the unsymmetrical arsino(phosphino)-
methane tBu2AsCH2PiPr2 reacts with [{(η4-C8H12)-
RhCl}2] by substitution of only one diolefin unit. The
(21) (a) Nolte, M. J .; Gafner, G.; Haines, L. M.. J . Chem. Soc. D 1969,
1406-1407. (b) Schrock, R. R.; Osborn, J . A. Inorg. Chem. 1970, 9,
2339-2343.
(22) (a) Albano, P.; Aresta, M.; Manassero, M. Inorg. Chem. 1980,
19, 1069-1072. (b) Longato, B.; Pilloni, G.; Graziani, R.; Casellato, U.
J . Organomet. Chem. 1991, 407, 369-376. (c) Aresta, M.; Quaranta,
E.; Tommasi, I. Gazz. Chim. Ital. 1993, 123, 271-278.
(23) Chiu, K. W.; Rzepa, H. S.; Sheppard, R. N.; Wilkinson, G.; Wong,
W.-K. Polyhedron 1982, 1, 809-817.
(24) (a) White, C.; Oliver, A. J .; Maitlis, P. M. J . Chem. Soc., Dalton
Trans. 1973, 1901-1907. (b) Musco, A.; Naegeli, R.; Venanzi, L. M.;
Albinati, A. J . Organomet. Chem. 1982, 228, C15-C18. (c) Werner,
H.; Wolf, J . Angew. Chem. 1982, 94, 309; Angew. Chem., Int. Ed. Engl.
1982, 21, 296-297. (d) Sutherland, B. R.; Cowie, M. Inorg. Chem. 1984,
23, 1290-1297. (e) Fryzuk, M. D.; Piers, W. E.; Rettig, S. J . Can. J .
Chem. 1992, 70, 2381-2389.
P r ep a r a t ion of [R h Cl(η4-C8H 12)(K-P -Cy2P CH2AsCy2)]
(2). A suspension of [{(η4-C8H12)RhCl}2] (145 mg, 0.30 mmol)
in pentane (5 mL) was treated with a solution of Cy2AsCH2-
PCy2 (268 mg, 0.60 mmol) in hexane (3 mL) and stirred for 10
(25) Manger, M.; Gevert, O.; Werner, H. Chem. Ber. 1997, 130,
1529-1531.
(26) Giordano, G.; Crabtree, R. H. Inorg. Synth. 1990, 28, 89-90.

2624 Organometallics, Vol. 17, No. 12, 1998
Werner et al.
mmol) in methanol (8 mL) and stirred for 20 min at room
temperature. An orange-yellow precipitate was formed, which
was separated from the mother liquor, washed with 6 mL of
methanol and then twice with 5 mL portions of pentane, and
dried: yield 182 mg (71%); mp 138 °C dec. 1H NMR (200 MHz,
CD2Cl2): δ 7.40-6.88 (m, 20H, C6H5), 5.51 (br s, 2H, HA), 5.10
(br s, 2H, HB), 3.03 [dd, J (RhH) ) 0.9, J (PH) ) 9.5 Hz, 2H,
AsCH2P], 2.50 [sept, J (HH) ) 7.0 Hz, 2H, AsCHCH3], 2.29 (br
s, 8H, CH2 of C8H12), 2.11 (m, 2H, PCHCH3), 1.29 (m, 24H,
AsCHCH3 and PCHCH3). 13C NMR (50.3 MHz, CD2Cl2): δ
164.3 [q, J (BC) ) 48.0 Hz, ipso-C of C6H5], 136.2 (s, meta-C of
C6H5), 125.8 (br s, ortho-C of C6H5), 121.9 (s, para-C of C6H5),
98.4 (m, dCHA), 89.6 (m, dCHB), 30.9, 30.1 (both s, CH2 of
C8H12), 28.8 (s, AsCHCH3), 26.6 [d, J (PC) ) 17.6 Hz, PCHCH3],
25.7 [d, J (PC) ) 18.4 Hz, AsCH2P], 20.6, 20.3 (both s,
AsCHCH3), 19.2 [d, J (PC) ) 2.8 Hz, PCHCH3], 19.0 (br s,
PCHCH3). 31P NMR (81.0 MHz, CD2Cl2): δ -1.1 [d, J (RhP)
) 128.8 Hz]. Anal. Calcd for C45H62AsBPRh (822.6): C, 65.71;
H, 7.60. Found: C, 65.66; H, 7.48.
F igu r e 3.
min at room temperature. The solvent was removed, and the
oily residue was washed with acetone (2 mL) and dried: yellow
solid, yield 345 mg (83%); mp 62 °C dec. 1H NMR (200 MHz,
C6D6): δ 4.71 (br s, 4H, dCH), 2.48-1.24 (br m, 54H, AsCH2P
and CH2 of C8H12 and C6H11). 31P NMR (81.0 MHz, C6D6): δ
25.2 [d, J (RhP) ) 143.9 Hz]. Anal. Calcd for C33H58AsClPRh
(699.1): C, 56.70; H, 8.36. Found: C, 57.18; H, 8.54.
P r ep a r a t ion of [{R h (η4-C8H 12)}{R h (K2-As,P -tBu 2As-
CH2P iP r 2)}(µ-Cl)2] (3). A suspension of [{(η4-C8H12)RhCl}2]
(424 mg, 0.86 mmol) in hexane (15 mL) was treated at room
temperature dropwise (over 45 min) with
a solution of
P r ep a r a t ion of [R h (η4-C8H 12)(K2-As,P -tBu 2AsCH2P i-
P r 2)]P F 6 (5a ). This was prepared as described for 4a , from
[{(η4-C8H12)RhCl}2] (403 mg, 0.82 mmol), tBu2AsCH2PiPr2 (524
mg, 1.64 mmol), and KPF6 (302 mg, 1.64 mmol): red crystals;
yield 551 mg (50%); mp 88 °C dec. 1H NMR (200 MHz, CD2-
Cl2): δ 5.56 (br s, 2H, HA), 5.04 (br s, 2H, HB), 3.16 [dd, J (RhH)
) 1.1, J (PH) ) 9.6 Hz, 2H, AsCH2P], 2.34 (br m, 10H, CH2 of
C8H12 and PCHCH3), 1.44 (s, 18H, AsCCH3), 1.37 [dd, J (PH)
) 11.5, J (HH) ) 7.3 Hz, 6H, PCHCH3], 1.27 [dd, J (PH) ) 15.0,
J (HH) ) 6.9 Hz, 6H, PCHCH3]. 13C NMR (50.3 MHz,
CD2Cl2): δ 98.7 [dd, J (RhC) ) 9.1, J (PC) ) 7.4 Hz, dCHA],
88.2 [d, J (RhC) ) 10.1 Hz, dCHB], 42.2 (br s, AsCCH3), 30.9
[d, J (RhC) ) 2.5 Hz, CH2 of C8H12], 30.1 (s, AsCCH3), 30.0 (br
s, CH2 of C8H12), 26.6 [d, J (PC) ) 14.8 Hz, PCHCH3], 26.3 [d,
J (PC) ) 16.6 Hz, AsCH2P], 19.4, 18.6 (both br s, PCHCH3).
31P NMR (81.0 MHz, CD2Cl2): δ -5.5 [d, J (RhP) ) 126.4 Hz,
iPr2P], -144.0 [sept, J (FP) ) 710.5 Hz, PF6-]. Anal. Calcd
for C23H46AsF6P2Rh (676.4): C, 40.84; H, 6.86. Found: C,
40.58; H, 6.64.
P r ep a r a t ion of [R h (η4-C8H 12)(K2-As,P -tBu 2AsCH2P i-
P r 2)]BP h 4 (5b). This was prepared as described for 4b, from
5a (171 mg, 0.25 mmol) and NaBPh4 (186 mg, 0.54 mmol) as
starting materials: orange-yellow solid; yield 186 mg (87%);
mp 150 °C dec. 1H NMR (400 MHz, CD2Cl2): δ 7.42-6.86 (m,
20H, C6H5), 5.58 (br s, 2H, HA), 4.91 (br s, 2H, HB), 2.96 [dd,
J (RhH) ) 0.8, J (PH) ) 9.4 Hz, 2H, AsCH2P], 2.66 (m, 4H, CH2
of C8H12), 2.17 (br m, 6H, CH2 of C8H12 and PCHCH3), 1.36 (s,
18H, AsCCH3), 1.25 [dd, J (PH) ) 15.6, J (HH) ) 7.2 Hz, 6H,
PCHCH3], 1.16 [dd, J (PH) ) 15.2, J (HH) ) 7.2 Hz, 6H,
PCHCH3]. 13C NMR (100.6 MHz, CD2Cl2): δ 164.3 [q, J (BC)
) 48.3 Hz, ipso-C of C6H5], 136.3 (s, meta-C of C6H5), 125.4
(br s, ortho-C of C6H5), 121.5 (s, para-C of C6H5), 98.5 [dd,
J (RhC) ) 9.3, J (PC) ) 6.2 Hz, dCHA], 87.9 [d, J (RhC) ) 9.4
Hz, dCHB], 42.0 (s, AsCCH3), 30.7 (s, CH2 of C8H12), 30.1 (s,
AsCCH3), 29.8 (s, CH2 of C8H12), 26.5 [d, J (PC) ) 16.1 Hz,
PCHCH3], 25.9 [d, J (PC) ) 16.1 Hz, AsCH2P], 19.3, 18.7 (both
s, PCHCH3). 31P NMR (162.0 MHz, CD2Cl2): δ -5.4 [d, J (RhP)
) 125.0 Hz]. Anal. Calcd for C47H62AsBPRh (850.7): C, 66.36;
H, 7.82. Found: C, 66.54; H, 7.66.
tBu2AsCH2PiPr2 (275 mg, 0.86 mmol) in hexane (20 mL). After
the addition had been completed, the reaction mixture was
stirred for 1 h at 25 °C. It was then filtered, and the filtrate
was brought to dryness in vacuo. The oily residue was
dissolved in warm acetone (8 mL), and the solution was stored
at -60 °C. Small orange-red crystals precipitated, which were
separated from the mother liquor, washed with 2 mL of
acetone (-40 °C), and dried: yield 448 mg (74%); mp 146 °C
dec. 1H NMR (400 MHz, CD2Cl2): δ 4.20 (br s, 4H, dCH of
C8H12), 2.84 [dd, J (RhH) ) 1.6, J (PH) ) 8.8 Hz, 2H, AsCH2P],
2.43 (br m, 4H, CH2 of C8H12), 2.06 (br m, 2H, PCHCH3), 1.72
(br m, 4H, CH2 of C8H12), 1.45 (br s, 18H, AsCCH3), 1.38 [dd,
J (PH) ) 16.0, J (HH) ) 7.2 Hz, 6H, PCHCH3], 1.27 [dd, J (PH)
) 14.4, J (HH) ) 7.2 Hz, 6H, PCHCH3]. 13C NMR (100.6 MHz,
CD2Cl2): δ 76.9 [d, J (RhC) ) 13.9 Hz, dCH of C8H12], 39.2 [d,
J (PC) ) 2.5 Hz, AsCCH3], 34.4 [d, J (PC) ) 16.4 Hz, AsCH2P],
31.3 (s, CH2 of C8H12), 30.0 (s, AsCCH3), 27.8 [d, J (PC) ) 17.6
Hz, PCHCH3], 20.1 [d, J (PC) ) 2.4 Hz, PCHCH3], 19.3 (br s,
PCHCH3). 31P NMR (162.0 MHz, CD2Cl2): δ 10.6 [d, J (RhP)
) 172.0 Hz]. Anal. Calcd for C23H46AsCl2PRh2 (705.2): C,
39.17; H, 6.57. Found: C, 39.14; H, 6.48.
P r ep a r a tion of [Rh (η4-C8H12)(K2-As,P -iP r 2AsCH2P iP r 2)]-
P F 6 (4a ). A solution of [{(η4-C8H12)RhCl}2] (360 mg, 0.73
mmol) in CH2Cl2 (20 mL) was treated with a solution of
iPr2AsCH2PiPr2 (465 mg, 1.58 mmol) in CH2Cl2 (15 mL) and
stirred for 10 min at room temperature. A change of color from
yellow to orange-red occurred. A solution of KPF6 (270 mg,
1.47 mmol) in methanol (15 mL) was then added dropwise,
and the reaction mixture was stirred for 2 h. An almost
colorless solid (KCl) precipitated, and a red solution was
formed. The solution was filtered, and the filtrate was brought
to dryness in vacuo. The oily residue was dissolved in 4 mL
of methanol (50 °C), and the solution was stored for 24 h at
-60 °C. Red needlelike crystals were obtained, which were
washed twice with 3 mL portions of pentane and dried: yield
724 mg (76%); mp 126 °C dec. 1H NMR (200 MHz, CD2Cl2):
δ 5.51 (br s, 2H, HA), 5.10 (br s, 2H, HB), 3.12 [d, J (PH) ) 10.0
Hz, 2H, AsCH2P], 2.52 [sept, J (HH) ) 6.0 Hz, 2H, AsCHCH3],
2.19 (br m, 10H, CH2 of C8H12 and PCHCH3), 1.36 (br m, 24H,
AsCHCH3 and PCHCH3). 13C NMR (50.3 MHz, CD2Cl2): δ
98.8 [dd, J (RhC) ) 8.5, J (PC) ) 7.3 Hz, dCHA], 89.4 [d, J (RhC)
) 9.3 Hz, dCHB], 30.8, 30.0 (both br s, CH2 of C8H12), 28.6 (br
s, AsCHCH3), 26.4 [d, J (PC) ) 16.7 Hz, PCHCH3], 25.6 [d,
J (PC) ) 17.6 Hz, AsCH2P], 20.4, 20.1 (both br s, AsCHCH3),
19.0 [d, J (PC) ) 3.7 Hz, PCHCH3], 17.8 (br s, PCHCH3). 31P
NMR (81.0 MHz, CD2Cl2): δ -1.3 [d, J (RhP) ) 126.6 Hz,
iPr2P], -144.0 [sept, J (FP) ) 712.8 Hz, PF6-]. Anal. Calcd
for C21H42AsF6P2Rh (648.3): C, 38.91; H, 6.53; As, 11.56.
Found: C, 39.10; H, 6.30; As, 11.11.
P r ep a r a tion of [Rh (η4-C8H12)(K2-As,P -Cy2AsCH2P Cy2)]-
P F 6 (6a ). A solution of [{(η4-C8H12)RhCl}2] (230 mg, 0.47
mmol) was treated with a solution of Cy2AsCH2PCy2 (430 mg,
0.95 mmol) in CH2Cl2 (5 mL) and stirred for 10 min at room
temperature. A solution of AgPF6 (238 mg, 0.94 mmol) in
CH2Cl2 (4 mL) was then added dropwise, and the reaction
mixture was stirred for 1 h under exclusion of light. An almost
colorless solid (AgCl) precipitated. The solution was filtered
and worked up as described for 3a : orange-red crystals; yield
558 mg (74%); mp 178 °C dec. 1H NMR (200 MHz, CD2Cl2):
δ 5.46 (br s, 2H, HA), 5.05 (br s, 2H, HB), 3.14 [br d, J (PH) )
9.3 Hz, 2H, AsCH2P], 2.36-1.70 (br m, 30H, CH2 of C8H12 and
AsCHCH2 and PCHCH2), 1.58-1.29 (br m, 24H, CH2 of C6H11).
P r ep a r a tion of [Rh (η4-C8H12)(K2-As,P -iP r 2AsCH2P iP r 2)]-
BP h 4 (4b). A solution of 4a (149 mg, 0.23 mmol) in methanol
(10 mL) was treated with a solution of NaBPh4 (212 mg, 0.62

Organometallic Rhodium Complexes
Organometallics, Vol. 17, No. 12, 1998 2625
13C NMR (50.3 MHz, CD2Cl2): δ 98.4 [dd, J (RhC) ) 9.1, J (PC)
) 6.6 Hz, dCHA], 89.0 [d, J (RhC) ) 9.0 Hz, dCHB], 38.6 (s,
AsCHCH2), 35.9 [d, J (PC) ) 16.2 Hz, PCHCH2], 30.8-26.0 (m,
CH2 of C8H12 and C6H11), 25.0 [d, J (PC) ) 18.7 Hz, AsCH2P].
31P NMR (81.0 MHz, CD2Cl2): δ -12.0 [d, J (RhP) ) 125.0 Hz,
Cy2P], -144.0 [sept, J (FP) ) 711.4 Hz, PF6-]. Anal. Calcd
for C33H58AsF6P2Rh (808.6): C, 49.06; H, 7.23; Rh, 12.73.
Found: C, 49.56; H, 7.74; Rh, 12.89.
) 10.6, J (PC) ) 8.3 Hz, dCHA], 82.7 [d, J (RhC) ) 8.3 Hz,
dCHB], 31.8, 29.9 (both s, CH2 of C8H12), 28.8 [d, J (PC) ) 4.6
Hz, AsCHCH3], 27.0 [d, J (PC) ) 17.6 Hz, PCHCH3], 19.3, 19.2
(both s, AsCHCH3), 18.3 [d, J (PC) ) 1.8 Hz, PCHCH3], 18.1
(s, PCHCH3), 13.5 [dd, J (RhC) ) J (PC) ) 3.2 Hz, AsCH2P],
8.9 [dd, J (RhC) ) 30.1, J (PC) ) 6.5 Hz, RhCH2]. 31P NMR
(81.0 MHz, CD2Cl2): δ 53.6 [d, J (RhP) ) 161.3 Hz]. Anal.
Calcd for C46H64AsBPRh (836.6): C, 66.04; H, 7.71. Found:
C, 65.29; H, 7.49.
P r ep a r a t ion of [R h (η4-C8H 12){K2-C,P -CH2As(tBu )2-
CH2P iP r 2}]P F 6 (8a ). This was prepared as described for 7a ,
from 5a (114 mg, 0.17 mmol) and a solution of CH2N2 (ca. 0.25
M, 2.04 mL, ca. 0.51 mmol) in ether as starting materials: red-
brown solid; yield 111 mg (95%); mp 128 °C dec. 1H NMR (400
MHz, CD2Cl2): δ 4.85 (br s, 2H, HA), 4.48 (br s, 2H, HB), 2.40
[dd, J (RhH) ) 0.8, J (PH) ) 7.4 Hz, 2H, AsCH2P], 2.16 (br m,
10H, CH2 of C8H12 and PCHCH3), 1.49 (s, 18H, AsCCH3), 1.35
[dd, J (PH) ) 15.2, J (HH) ) 6.8 Hz, 6H, PCHCH3], 1.21 [dd,
J (PH) ) 14.6, J (HH) ) 7.6 Hz, 6H, PCHCH3], 0.97 (br s, 2H,
RhCH2). 13C NMR (100.6 MHz, CDCl3): δ 95.4 [dd, J (RhC) )
10.7, J (PC) ) 8.6 Hz, dCHA], 80.2 [d, J (RhC) ) 8.3 Hz, dCHB],
42.3 [d, J (PC) ) 3.4 Hz, AsCCH3], 31.6 [br d, J (RhC) ) 1.7
Hz, CH2 of C8H12], 29.7 (br s, CH2 of C8H12), 28.2 (s, AsCCH3),
27.6 [d, J (PC) ) 17.0 Hz, PCHCH3], 19.5 [d, J (PC) ) 2.4 Hz,
PCHCH3], 18.7 (br s, PCHCH3), 15.0 [dd, J (RhC) ) 2.0, J (PC)
) 6.2 Hz, AsCH2P], 7.7 [dd, J (RhC) ) 30.1, J (PC) ) 7.2 Hz,
RhCH2]. 31P NMR (162.0 MHz, CDCl3): δ 53.4 [d, J (RhP) )
161.2 Hz, iPr2P], -144.2 [sept, J (FP) ) 712.7 Hz, PF6-]. Anal.
Calcd for C24H48AsF6P2Rh (690.4): C, 41.75; H, 7.01. Found:
C, 42.19; H, 6.81.
P r ep a r a tion of [Rh (η4-C8H12)(K2-As,P -Cy2AsCH2P Cy2)]-
BP h 4 (6b). This was prepared as described for 4b, from 6a
(251 mg, 0.31 mmol) and NaBPh4 (212 mg, 0.62 mmol) as
starting materials: yellow solid; yield 284 mg (93%); mp 164
°C dec. 1H NMR (200 MHz, CD2Cl2): δ 7.40-6.90 (m, 20H,
C6H5), 5.39 (br s, 2H, HA), 4.99 (br s, 2H, HB), 2.98 [br d, J (PH)
) 9.4 Hz, 2H, AsCH2P], 2.27-1.79 (br m, 30H, CH2 of C8H12
and AsCHCH2 and PCHCH2), 1.39-1.26 (br m, 24H, CH2 of
C6H11). 13C NMR (50.3 MHz, CD2Cl2): δ 164.2 [q, J (BC) )
49.3 Hz, ipso-C of C6H5], 136.2 (s, meta-C of C6H5), 125.3 (br
s, ortho-C of C6H5), 121.4 (s, para-C of C6H5), 98.1 [dd, J (RhC)
) 9.1, J (PC) ) 6.5 Hz, dCHA], 88.7 [d, J (RhC) ) 8.8 Hz,
dCHB], 38.4 (s, AsCHCH2), 35.7 [d, J (PC) ) 16.0 Hz, PCHCH2],
30.6-27.2 (m, CH2 of C8H12 and C6H11), 26.7 [d, J (PC) ) 12.7
Hz, PCHCH2], 26.3 [d, J (PC) ) 9.7 Hz, PCHCH2], 25.7, 25.6
(both s, CH2 of C6H11), 25.0 [d, J (PC) ) 18.5 Hz, AsCH2P]. 31
P
NMR (81.0 MHz, CD2Cl2): δ -11.9 [d, J (RhP) ) 125.0 Hz].
Anal. Calcd for C57H78AsBPRh (982.9): C, 69.66; H, 8.00.
Found: C, 69.76; H, 7.94.
P r ep a r a t ion of [R h (η4-C8H 12){K2-C,P -CH2As(iP r )2-
CH2P iP r 2}]P F 6 (7a ). A solution of 4a (132 mg, 0.20 mmol)
in THF (6 mL) was treated at -50 °C with a solution of CH2N2
(ca. 0.25 M, 2.50 mL, ca. 0.63 mmol) in ether. Under slightly
reduced pressure, the solution was slowly warmed to room
temperature and stirred for 45 min. The resulting brown
solution was brought to dryness in vacuo. The oily residue
was washed several times with pentane and dried: yellow
solid; yield 109 mg (81%); mp 60 °C dec. 1H NMR (400 MHz,
CDCl3): δ 4.95 (br s, 2H, HA), 4.35 (br s, 2H, HB), 2.72 [sept,
J (HH) ) 7.2 Hz, 2H, AsCHCH3], 2.36 [dd, J (RhH) ) 0.8, J (PH)
) 8.0 Hz, 2H, AsCH2P], 2.15 (br m, 10H, CH2 of C8H12 and
PCHCH3), 1.42, 1.37 [both d, J (HH) ) 7.2 Hz, 12H, AsCHCH3],
1.24 (m, 12H, PCHCH3), 0.98 [dd, J (RhH) ) J (PH) ) 1.6 Hz,
2H, RhCH2]. 13C NMR (100.6 MHz, CDCl3): δ 96.8 [dd, J (RhC)
) 10.6, J (PC) ) 8.1 Hz, dCHA], 81.7 [d, J (RhC) ) 8.4 Hz,
dCHB], 31.7 [d, J (RhC) ) 1.9 Hz, CH2 of C8H12], 28.4 [d, J (PC)
) 4.2 Hz, AsCHCH3], 26.7 [d, J (PC) ) 18.5 Hz, PCHCH3], 19.1
(br s, AsCHCH3), 18.2, 17.9 (both s, PCHCH3), 13.8 [br dd,
J (RhC) ) 2.3, J (PC) ) 8.2 Hz, AsCH2P], 8.1 [dd, J (RhC) )
30.0, J (PC) ) 7.2 Hz, RhCH2]. 31P NMR (162.0 MHz, CDCl3):
δ 52.5 [d, J (RhP) ) 159.7 Hz, iPr2P], -144.3 [sept, J (FP) )
712.7 Hz, PF6-]. Anal. Calcd for C22H44AsF6P2Rh (662.4): C,
39.89; H, 6.70; As, 11.31; Rh, 15.54. Found: C, 40.08; H, 6.53;
As, 10.62; Rh, 15.00.
P r ep a r a t ion of [R h (η4-C8H 12){K2-C,P -CH2As(iP r )2-
CH2P iP r 2}]BP h 4 (7b). A solution of 7a (69 mg, 0.10 mmol)
in methanol (6 mL) was treated with a solution of NaBPh4
(72 mg, 0.21 mmol) in methanol (5 mL) and stirred for 10 min
at room temperature. A gradual change of color from yellow
to light yellow occurred, and a yellow solid precipitated. The
mother liquor was removed, and the residue was washed twice
with 5 mL portions of methanol and twice with 5 mL portions
of pentane and dried: yield 72 mg (86%); mp 102 °C dec. 1H
NMR (200 MHz, CD2Cl2): δ 7.31-6.87 (m, 20H, C6H5), 5.04
(br s, 2H, HA), 4.37 (br s, 2H, HB), 2.59 (m, 2H, AsCHCH3),
2.24 (br s, 8H, CH2 of C8H12), 2.09 (br m, 2H, PCHCH3), 1.98
[d, J (PH) ) 6.6 Hz, 2H, AsCH2P], 1.38, 1.35 [both d, J (HH) )
7.3 Hz, 12H, AsCHCH3], 1.23 [dd, J (PH) ) 16.1, J (HH) ) 6.8
Hz, 6H, PCHCH3], 1.20 [dd, J (PH) ) 14.2, J (HH) ) 6.6 Hz,
6H, PCHCH3], 1.05 [dd, J (RhH) ) J (PH) ) 1.8 Hz, 2H,
RhCH2]. 13C NMR (50.3 MHz, CD2Cl2): δ 164.1 [q, J (BC) )
49.9 Hz, ipso-C of C6H5], 136.1 (s, meta-C of C6H5), 125.7 (s,
ortho-C of C6H5), 121.9 (s, para-C of C6H5), 98.5 [dd, J (RhC)
P r ep a r a t ion of [R h (η4-C8H 12){K2-C,P -CH2As(tBu )2-
CH2P iP r 2}]BP h 4 (8b). A solution of 5b (60 mg, 0.07 mmol)
in CH2Cl2 (4 mL) was treated at -60 °C with a solution of
CH2N2 (ca. 0.25 M, 0.84 mL, ca. 0.21 mmol) in ether, which
led to a change of color from light red to yellow. The solution
was slowly warmed to room temperature and stirred for 15
min. The reaction mixture was filtered, and the filtrate was
concentrated to ca. 2 mL in vacuo. The concentrate was
layered with pentane (8 mL) and stored at -25 °C for 48 h.
Light yellow crystals precipitated, which were separated from
the mother liquor, washed with pentane (5 mL), and dried:
yield 57 mg (93%); mp 115 °C dec. 1H NMR (400 MHz,
CDCl2): δ 7.40-6.88 (m, 20H, C6H5), 4.85 (br s, 2H, HA), 4.45
(br s, 2H, HB), 2.17 (m, 8H, CH2 of C8H12), 1.98 (br m, 2H,
PCHCH3), 1.94 [dd, J (RhH) ) 0.8, J (PH) ) 7.2 Hz, 2H,
AsCH2P], 1.35 (s, 18H, AsCCH3), 1.25 [dd, J (PH) ) 14.8, J (HH)
) 7.2 Hz, 6H, PCHCH3], 1.16 [dd, J (PH) ) 14.8, J (HH) ) 7.2
Hz, 6H, PCHCH3], 0.90 [dd, J (RhH) ) J (PH) ) 2.0 Hz, 2H,
RhCH2]. 13C NMR (100.6 MHz, CDCl3): δ 164.3 [q, J (BC) )
49.3 Hz, ipso-C of C6H5], 136.3 (s, meta-C of C6H5), 125.4 [q,
J (BC) ) 3.0 Hz, ortho-C of C6H5], 121.5 (s, para-C of C6H5),
96.4 [dd, J (RhC) ) 10.7, J (PC) ) 7.9 Hz, dCHA], 80.8 [br d,
J (RhC) ) 8.4 Hz, dCHB], 42.4 [d, J (PC) ) 3.4 Hz, AsCCH3],
30.7 [d, J (RhC) ) 1.6 Hz, CH2 of C8H12], 29.7 (s, CH2 of C8H12),
28.3 (s, AsCCH3), 27.7 [d, J (PC) ) 17.5 Hz, PCHCH3], 19.5 [d,
J (PC) ) 2.1 Hz, PCHCH3], 18.9 (br s, PCHCH3), 14.8 [d, J (PC)
) 2.6 Hz, AsCH2P], 7.5 [dd, J (RhC) ) 30.1, J (PC) ) 7.2 Hz,
RhCH2]. 31P NMR (162.0 MHz, CDCl3): δ 54.0 [d, J (RhP) )
161.2 Hz]. Anal. Calcd for C48H68AsBPRh (864.7): C, 66.67;
H, 7.93. Found: C, 66.09; H, 8.11.
P r ep a r a t ion
of [R h (η4-C8H 12){K2-C,P -CH2As(Cy)2-
CH2P Cy2}]P F 6 (9). A solution of 6a (73 mg, 0.09 mmol) in
THF (3 mL) was treated at -30 °C with a solution of CH2N2
(ca. 0.30 M, 0.90 mL, ca. 0.27 mmol) in ether. Under slightly
reduced pressure, the solution was slowly warmed to room
temperature and then stirred for 30 min. The resulting brown
solution was brought to dryness in vacuo. The oily residue
was extracted with CH2Cl2 (5 mL), and the solvent was
removed. The remaining solid was washed twice with 15 mL
portions of pentane/ether (4:1) and with pentane (10 mL) and
dried: light yellow solid; yield 70 mg (94%); mp 112 °C dec.

2626 Organometallics, Vol. 17, No. 12, 1998
Ta ble 3. Cr ysta llogr a p h ic Da ta for 3 a n d 7b
Werner et al.
formula
C23H46AsCl2PRh2 (3)
705.71
C23H64AsBPRh (7b)
836.58
fw
cryst size, mm3
0.2 × 0.2 × 0.07
monoclinic
P21/c (No. 14)
24 rflns, 10° < θ < 15°
10.744(1)
20.174(2)
14.35(2)
111.20(5)
2900(4)
0.18 × 0.15 × 0.12
cryst syst
space group
cell dimens determn
monoclinic
P21/c (No. 14)
25 rflns, 10° < θ < 15°
15.580(3)
13.617(1)
20.386(4)
93.674(9)
4316(1)
a, Å
b, Å
c, Å
â, deg
V, A3
Z
4
4
d
calcd, g cm-3
1.617
1.287
diffractometer
CAD4 (Enraf-Nonius)
radiation (λ, Å)
Mo KR (0.710 73)
filter factor (Zr filter)
temp, K
15.4
293(2)
2.503
ω/θ
54
5465
15.4
293(2)
1.217
ω/θ
46
µ, mm-1
scan method
2θ(max), deg
total no. of rflns
7263
no. of unique rflns
no. of obsd rflns (I > 2σ(I))
no. of rflns used for refinement
no. of params refined
final R indices (I > 2σ(I))
R indices (all data)
rfln:param ratio
5135 (R(int) ) 0.0263)
5984 (R(int) ) 0.0348)
3126
3814
5132
280
5982
525
R1 ) 0.0457, wR2 ) 0.0718a
R1 ) 0.0968, wR2 ) 0.0943a
18.33
R1 ) 0.0529, wR2 ) 0.0984a
R1 ) 0.1058, wR2 ) 0.1261a
11.39
resid electron density, e Å-3
0.448/-0.413
0.413/-0.338
a
2
2
2
w-1 ) [σ2Fo + (0.0162P)2 + 6.5172P] (3) and w-1 ) [σ2Fo + (0.0391P)2 + 9.8224P] (7b), where P ) (Fo + 2Fc2)/3.
1H NMR (200 MHz, CD2Cl2): δ 4.89 (br s, 2H, HA), 4.29 (br s,
2H, HB), 2.58-1.17 (br m, 54H, AsCH2P and CH2 of C8H12 and
C6H11), 0.91 (br s, 2H, RhCH2). 13C NMR (50.3 MHz, CD2Cl2):
δ 96.9 [dd, J (RhC) ) 10.6, J (PC) ) 8.1 Hz, dCHA], 82.4 [d,
J (RhC) ) 10.3 Hz, dCHB], 38.5 [d, J (PC) ) 1.9 Hz, AsCHCH2],
36.5 [d, J (PC) ) 17.6 Hz, PCHCH2], 31.8 (br s, CH2 of C8H12),
30.1-25.7 (m, CH2 of C8H12 and AsCy2 and PCy2), 12.7 (br s,
AsCH2P), 9.1 [dd, J (RhC) ) 30.3, J (PC) ) 7.2 Hz, RhCH2].
31P NMR (81.0 MHz, CD2Cl2): δ 41.8 [d, J (RhP) ) 160.0 Hz,
Cy2P], -143.9 [sept, J (FP) ) 711.4 Hz, PF6-]. Anal. Calcd
for C34H60AsF6P2Rh (822.6): C, 49.64; H, 7.35; Rh, 12.51.
Found: C, 49.94; H, 6.90; Rh, 12.51.
J (RhH) ) 1.1, J (PH) ) 9.3 Hz, 2H, AsCH2P], 1.96 (br m, 2H,
PCHCH3), 1.14 (s, 18H, AsCCH3), 1.10 (br m, 12H, PCHCH3).
13C NMR (50.3 MHz, CD2Cl2): δ 136.2, 126.1, 123.0 (all s,
C6H5), 99.7, 98.3, 91.2 (all s, η6-C6H5), 39.7 (s, AsCCH3), 29.4
[d, J (PC) ) 18.5 Hz, PCHCH3], 29.2 [d, J (PC) ) 18.5 Hz,
AsCH2P], 29.1 (s, AsCCH3), 19.3, 19.1 (both s, PCHCH3); the
signals of the ipso-C of η6-C6H5 and C6H5 were not exactly
located. 31P NMR (81.0 MHz, CD2Cl2): δ 11.3 [d, J (RhP) )
172.9 Hz]. Anal. Calcd for C39H54AsBPRh (742.5): C, 63.09;
H, 7.33. Found: C, 62.89; H, 7.67.
P r ep a r a tion of [{Rh H(K2-As,P -Cy2AsCH2P Cy2)}2(µ-H)-
(µ-O2CCF 3)2]P F 6 (12). A solution of 6a (105 mg, 0.13 mmol)
in CH2Cl2 (6 mL) was treated with CF3CO2H (30 µL, 0.39
mmol) and then stirred under H2 (1.0 bar) for 10 min at room
temperature. A change of color from orange-yellow to light
yellow occurred. After the solvent was removed in vacuo, an
oily residue was obtained which upon treatment with 10 mL
of ether (twice) and 5 mL of pentane (twice) gave a light yellow,
almost air stable solid: yield 70 mg (73%); mp 57 °C dec. IR
(CH2Cl2): ν(RhH) 2100, ν(OCOasym) 1672, ν(OCOsym) 1447,
P r ep a r a t ion
of [(η6-C6H 5BP h 3)R h (K2-As,P -iP r 2As-
CH2P iP r 2)] (10). A slow stream of H2 was passed through a
solution of 4b (182 mg, 0.22 mmol) in CH2Cl2 (10 mL) for 45
s. While the solution was stirred under H2 for 1.5 h at room
temperature, a light red solid precipitated. The solvent was
removed in vacuo, and the residue was washed twice with 3
mL portions of pentane and dried: light red solid; yield 145
mg (92%); mp 68 °C dec. 1H NMR (200 MHz, CD2Cl2): δ 7.33-
7.00 (br m, 15H, C6H5), 6.58 (br m, 1H, para-H of η6-C6H5),
6.37 [br d, J (HH) ) 5.8 Hz, 2H, ortho-H of η6-C6H5], 5.90 (br
m, 2H, meta-H of η6-C6H5), 2.71 [dd, J (RhH) ) 1.5, J (PH) )
9.5 Hz, 2H, AsCH2P], 2.14 [sept, J (HH) ) 6.9 Hz, 2H,
AsCHCH3], 1.85 (br m, 2H, PCHCH3), 1.05 (br m, 24H,
PCHCH3 and AsCHCH3). 13C NMR (50.3 MHz, CD2Cl2): δ
135.9, 126.1, 123.0 (all s, C6H5), 100.6, 96.4, 92.0 (all s, η6-
C6H5), 28.1 [d, J (PC) ) 18.5 Hz, AsCH2P], 28.1 [d, J (PC) )
1.9 Hz, AsCHCH3], 27.5 [d, J (PC) ) 20.4 Hz, PCHCH3], 19.9,
19.3 (both s, AsCHCH3), 18.7 [d, J (PC) ) 2.8 Hz, PCHCH3],
18.3 (s, PCHCH3); the signals of the ipso-C of η6-C6H5 and C6H5
were not exactly located. 31P NMR (81.0 MHz, CD2Cl2): δ 16.8
[d, J (RhP) ) 169.9 Hz]. Anal. Calcd for C37H50AsBPRh
(714.4): C, 62.21; H, 7.05. Found: C, 61.48; H, 7.03.
ν(CF) 1200, 1149 cm-1 1H NMR (200 MHz, CD2Cl2): δ 3.03,
.
2.71-1.34 (all br m, 92H, C6H11 and AsCH2P), -17.52 [tt,
J (RhH) ) 25.0, J (PH) ) 10.9 Hz, 1H, RhHRh], -17.92 [dd,
J (RhH) ) 15.0, J (PH) ) 24.4 Hz, 2H, RhH]. 13C NMR (50.3
MHz, CD2Cl2): δ 168.5 [q, J (FC) ) 36.8 Hz, O2CCF3], 116.2
[q, J (FC) ) 292.5 Hz, CF3], 39.8, 38.5 (both s, AsCHCH2), 36.4
[d, J (PC) ) 26.8 Hz, PCHCH2], 35.4 [d, J (PC) ) 21.5 Hz,
PCHCH2], 31.4-25.7 (br m, CH2 of AsCy2 and PCy2), 25.1 [d,
br, J (PC) ) 23.1 Hz, AsCH2P]. 19F NMR (188.3 MHz,
CD2Cl2): δ -73.7 [d, J (PF) ) 711.3 Hz, PF6-], -75.2 (s, CF3).
31P NMR (81.0 MHz, CD2Cl2): δ 29.5 [d, J (RhP) ) 111.2 Hz,
Cy2P], -144.0 [sept, J (FP) ) 711.3 Hz, PF6-]. Anal. Calcd
for C54H95As2F12P3Rh2 (1484.9): C, 43.68; H, 6.45. Found: C,
43.47; H, 6.24.
P r ep a r a t ion of [(η6-C6H 5BP h 3)R h (K2-As,P -tBu 2As-
CH2P iP r 2)] (11). This was prepared as described for 10, from
5b (142 mg, 0.17 mmol) and H2 as starting materials: orange-
yellow solid; yield 110 mg (87%). 1H NMR (200 MHz,
CD2Cl2): δ 7.41-7.03 (br m, 15H, C6H5), 6.70 (br m, 1H,
para-H of η6-C6H5), 6.25 [br d, J (HH) ) 6.2 Hz, 2H, ortho-H of
η6-C6H5], 5.84 (br m, 2H, meta-H of η6-C6H5), 2.81 [dd,
X-r a y Str u ctu r e Deter m in a tion of Com p ou n d s 3 a n d
7b. Single crystals of 3 were grown from 2-propanol at 0 °C
and single crystals of 7b by diffusion of pentane into a
saturated solution of 7b in THF at room temperature. Crystal
data collection parameters are summarized in Table 3. In-
tensity data were corrected by Lorentz and polarization effects,
and a semiempirical absorption correction was applied in each

Organometallic Rhodium Complexes
Organometallics, Vol. 17, No. 12, 1998 2627
case (minimum transmission 75.30% (3), 93.88% (7b)). The
structures were solved by direct methods (SHELXS-86).27
Atomic coordinates and anisotropic displacement parameters
of all non-hydrogen atoms were refined by full-matrix least
squares on F2 (SHELXL-93).28 The positions of all hydrogen
atoms were calculated according to ideal geometry and refined
by full-matrix least squares on F2 using the riding method,
except for H9a and H9b of 3, which were found and refined
without restrictions.
Fonds der Chemischen Industrie for financial support
(in particular for a doctoral grant to M.M.). Moreover,
we gratefully acknowledge support by R. Schedl and C.
P. Kneis (DTA and elemental analysis), M.-L. Scha¨fer
and Dr. W. Buchner (NMR spectra), and Degussa AG
(gifts of chemicals).
Su p p or tin g In for m a tion Ava ila ble: Tables of data col-
lection parameters, bond lengths and angles, positional and
thermal parameters, and least-squares planes for 3 and 7b
(14 pages). Ordering information is given on any current
masthead page.
Ack n ow led gm en t . We thank the Deutsche For-
schungsgemeinschaft (Grant No. SFB 347) and the
(27) Sheldrick, G. M. SHELXS-86; University of Go¨ttingen, Go¨ttin-
gen, Germany, 1986.
(28) Sheldrick, G. M. SHELXL-93; University of Go¨ttingen, Go¨ttin-
gen, Germany, 1993.
OM971085O