[Rh(μ-OH)(PiPr3)2]2: Versatile tool for the binding of alkynyl, diynyl, and diyndiyl ligands to an electron-rich rhodium(I) center

Article abstract of DOI:10.1021/om9601155

The reaction of [Rh(μ-OH)(PiPr₃)₂]₂ (1) with NaOH under phase-tranfer conditions afforded the labile and extremely air-sensitive hydroxorhodium(I) complex [Rh(μ-OH)(PiPr₃)₂]₂ (2) in 80% yield. The X-ray crystal structure analysis of 2 confirmed the dimeric nature of the molecule containing a nearly planar Rh₂O₂ unit. Compound 2 reacted with CO to yield trans-[Rh(OH)(CO)(PiPr₃)₂] (4) and with PhC≡CSiMe₃, in the presence of pyridine or CO, to give trans-[Rh(C≡CPh)(py)(PiPr₃)₂] (5) and trans-[Rh(C≡CPh)(CO)(PiPr₃)₂] (6), respectively. Treatment of 4 with Me₃SiC≡CC≡CSiMe₃ yielded the binuclear diyndiyl complex [(PiPr₃)₂-(CO)Rh(C≡CC≡C)Rh(CO)(PiPr ₃)₂] (7), while the corresponding reaction of 4 with Me₃-SiC≡CC≡CSnPh₃ gave the mononuclear product trans-[Rh(C≡CC≡CSiMe3)(CO)(PzPr₃)₂] (8). The X-ray crystal structure analysis of 7 revealed the presence of an almost linear Rh-C₄-Rh linkage with the midpoint of the central C-C bond as a crystallographic center of symmetry.

Full text of DOI:10.1021/om9601155

2806
Organometallics 1996, 15, 2806-2809
[Rh (µ-OH)(P iP r 3)2]2: Ver sa tile Tool for th e Bin d in g of
Alk yn yl, Diyn yl, a n d Diyn d iyl Liga n d s to a n
Electr on -Rich Rh od iu m (I) Cen ter †
Olaf Gevert, J ustin Wolf, and Helmut Werner*
Institut fu¨r Anorganische Chemie der Universita¨t Wu¨rzburg, Am Hubland,
D-97074 Wu¨rzburg, Germany
Received February 14, 1996X
The reaction of [RhCl(PiPr3)2]2 (1) with NaOH under phase-tranfer conditions afforded
the labile and extremely air-sensitive hydroxorhodium(I) complex [Rh(µ-OH)(PiPr3)2]2 (2)
in 80% yield. The X-ray crystal structure analysis of 2 confirmed the dimeric nature of the
molecule containing a nearly planar Rh2O2 unit. Compound 2 reacted with CO to yield trans-
[Rh(OH)(CO)(PiPr3)2] (4) and with PhCtCSiMe3, in the presence of pyridine or CO, to give
trans-[Rh(CtCPh)(py)(PiPr3)2] (5) and trans-[Rh(CtCPh)(CO)(PiPr3)2] (6), respectively.
Treatment of 4 with Me3SiCtCCtCSiMe3 yielded the binuclear diyndiyl complex [(PiPr3)2-
(CO)Rh(CtCCtC)Rh(CO)(PiPr3)2] (7), while the corresponding reaction of 4 with Me3-
SiCtCCtCSnPh3 gave the mononuclear product trans-[Rh(CtCCtCSiMe3)(CO)(PiPr3)2] (8).
The X-ray crystal structure analysis of 7 revealed the presence of an almost linear Rh-
C4-Rh linkage with the midpoint of the central C-C bond as a crystallographic center of
symmetry.
Sch em e 1
In tr od u ction
In the search for reactive halide-free bis(triisopropyl-
phosphine)rhodium(I) complexes of general composition
[RhX(PiPr3)2], we recently described the preparation of
[Rh(η2-O2CCH3)(PiPr3)2] and similar (carboxylato)-
rhodium(I) derivatives.1 The four-coordinate acetato
compound reacts with terminal alkynes HCtCR (R )
Me, Ph) by oxidative addition to give the octahedral
complexes [RhH(CtCR)(η2-O2CCH3)(PiPr3)2], which ei-
ther thermally or photochemically rearrange to the
isomeric vinylidene species trans-[Rh(η1-O2CCH3)-
(dCdCHR)(PiPr3)2].2 The synthesis of alkynyl(vinyl)-
and alkynyl(butadienyl)rhodium(III) complexes from
[Rh(η2-O2CCH3)(PiPr3)2] as starting material has also
been reported.3
In continuation of this work we have now prepared
the hydroxo derivative [Rh(OH)(PiPr3)2]2 (2), which in
the solid state is a dimer and which reacts at low
temperatures with CO to yield the mononuclear com-
pound trans-[Rh(OH)(CO)(PiPr3)2] (4). Treatment of
this highly reactive species with SiMe3- and SnPh3-
substituted alkynes and diynes provides an entry into
the chemistry of alkynyl-, diynyl- and diyndiylrhodium
carbonyl complexes.
process is somewhat similar to the synthesis of [Rh(OH)-
(PPh3)2]2 from [RhCl(PPh3)3] and KOH, recently re-
ported by Alper et al.,5 which also proceeds in benzene/
water under biphasic conditions but does not need a
phase-transfer catalyst. Compound 2 is an orange, very
air-sensitive solid which is soluble in pentane and
benzene, almost insoluble in acetone, and decomposes
slowly in ether, THF, and chlorinated solvents. Also
in the solid state and at room temperature, even under
argon, slow decomposition occurs. The 31P NMR spec-
trum of 2 in C6D6 displays a doublet at 61.3 ppm with
a Rh-P coupling of 183.1 Hz which is almost identical
to the J (RhP) value of [Rh(OH)(PPh3)2]2 (188 Hz).5
The X-ray crystal structure analysis of 2 (Figure 1)
confirms the dimeric nature of the molecule in which
the two Rh(PiPr3)2 moieties are bridged by the hydroxy
groups. This situation is similar to that found in both
Resu lts a n d Discu ssion
Reaction of the chloro compound 14 in benzene with
20% aqueous NaOH in the presence of [PhCH2NEt3]Cl
(TEBA) results in a clean and nearly quantitative
formation of the hydroxo complex 2 (Scheme 1). This
6
[Rh(OH)(PPh3)2]2 and [Rh(OH)(COD)]2 (COD ) cyclo-
octa-1,5-diene)7 as well as in the chloro derivative 1.4b
The angles P1-Rh1-P2 and P3-Rh2-P4 in 2 are
105.68(5) and 105.57(5)°, respectively, and thus signifi-
† Dedicated to Professor J o¨rn Mu¨ller on the occasion of his 60th
birthday.
X Abstract published in Advance ACS Abstracts, May 1, 1996.
(1) (a) Scha¨fer, M.; Wolf, J .; Werner, H. J . Chem. Soc., Chem.
Commun. 1991, 1341-1343. (b) Werner, H.; Scha¨fer, M.; Nu¨rnberg,
O.; Wolf, J . Chem. Ber. 1994, 127, 27-38.
(4) (a) Preparation: Werner, H.; Wolf, J .; Ho¨hn, A. J . Organomet.
Chem. 1985, 287, 395-407. (b) X-ray crystal structure: Binger, P.;
Haas, J .; Glaser, G.; Goddard, R.; Kru¨ger, C. Chem. Ber. 1994, 127,
1927-1929.
(5) Grushin, V. V.; Kuznetsov, V. F.; Bensimon, C.; Alper, H.
Organometallics 1995, 14, 3927-3932.
(6) Brune, H.-A.; Hemmer, R.; Unsin, J .; Holl, K.; Thewalt, U. Z.
Naturforsch. 1988, 43b, 487-490.
(2) Scha¨fer, M.; Wolf, J .; Werner, H. J . Organomet. Chem. 1995,
485, 85-100.
(3) Werner, H.; Scha¨fer, M.; Wolf, J .; Peters, K.; von Schnering, H.
G. Angew. Chem. 1995, 107, 213-215; Angew. Chem., Int. Ed. Engl.
1995, 34, 191-194.
S0276-7333(96)00115-X CCC: $12.00 © 1996 American Chemical Society

[Rh(µ-OH)(PiPr3)2]2
Organometallics, Vol. 15, No. 12, 1996 2807
F igu r e 2.
Sch em e 2
F igu r e 1.
Ta ble 1. Selected Bon d Dista n ces a n d An gles w ith
Esd ’s for Com p ou n d 2
Bond Distances (Å)
Rh1-P1
Rh1-P2
Rh1-O1
Rh1-O2
Rh1-Rh2
2.241(1)
2.233(1)
2.127(3)
2.110(4)
3.330(1)
Rh2-P3
Rh2-P4
Rh2-O1
Rh2-O2
2.238(1)
2.229(1)
2.106(4)
2.122(4)
Bond Angles (deg)
P1-Rh1-P2
P1-Rh1-O1
P1-Rh1-O2
P2-Rh1-O2
P2-Rh1-O1
O1-Rh1-O2
Rh1-O1-Rh2
105.68(5)
88.1(1)
163.9(1)
90.4(1)
166.2(1)
75.9(2)
103.7(2)
P3-Rh2-P4
P3-Rh2-O1
P3-Rh2-O2
P4-Rh2-O2
P4-Rh2-O1
O1-Rh2-O2
Rh1-O2-Rh2
105.57(5)
165.1(1)
89.4(1)
165.1(1)
89.1(1)
76.1(2)
103.8(2)
cantly larger than in 1 [97.2(1)°].4b In contrast to 1 and
[Rh(OH)(PPh3)2]2, the central Rh2O2 core is not com-
pletely planar; the oxygen and rhodium atoms deviate
by (0.050(1) Å from the best plane calculated for this
unit. The four phosphorus atoms are beneath this
plane, the dihedral angle between the planes [P1, Rh1,
P2] and [P3, Rh2, P4] being 9.6(1)°. The Rh-O bond
lengths in 2 (mean value 2.116(4) Å; see Table 1) are
somewhat larger than in the bis(triphenylphosphine)
analogue [2.064(3) and 2.067(3) Å] and the same is true
for the Rh-P distances.
The dimeric compound 2 reacts at low temperatures
with CO by bridge cleavage to yield the mononuclear
carbonyl complex 4 (Scheme 1) which has originally
been prepared either from trans-[RhCl(CO)(PiPr3)2] and
NaOiPr in 2-propanol8 or from [RhH(PiPr3)3] when used
as a catalyst in the water-gas shift reaction.9 We found
that 4 is also accessible by a one-pot synthesis, starting
with [RhCl(C8H14)2]2 (3) via 1 and trans-[RhCl(CO)-
(PiPr3)2]8,10 as intermediates. The final replacement of
Cl- by OH- to give 4 proceeds with KOtBu and tert-
butyl alcohol without using a phase-transfer catalyst.
Most remarkably, both hydroxo compounds 2 and 4
are highly reactive toward silylated and stannylated
alkynes and are thus excellent precursors for the
synthesis of alkynyl-, diynyl- and diyndiylrhodium(I)
derivatives (Scheme 2). Complex
2 reacts with
PhCtCSiMe3 in the presence of Lewis bases such as
pyridine or carbon monoxide to form the mononuclear
compounds trans-[Rh(CtCPh)(py)(PiPr3)2] (5) and trans-
[Rh(CtCPh)(CO)(PiPr3)2] (6), respectively. Other pre-
parative routes to 5 and 6 have already been re-
ported, using either [RhH(CtCPh)Cl(py)(PiPr3)2] or
[RhH(CtCPh)(O2CCH3)(CO)(PiPr3)2] as starting mate-
rials.2,11
The hydroxo-carbonyl complex 4, on treatment with
a 0.5 molar equiv of Me3SiCtCCtCSiMe3, affords the
binuclear compound [(PiPr3)2(CO)Rh(CtCCtC)Rh(CO)-
(PiPr3)2] (7) containing a “naked” C4 bridge12 in 75%
yield. 7 is a yellow crystalline solid which is moderately
air-stable and easily soluble in ether and hydrocarbon
solvents. Since the IR and 13C NMR spectra of 7 did
not conclusively support the structural proposal for 7,
an X-ray crystal structural investigation was carried
out. As shown in Figure 2, the two Rh(CO)(PiPr3)2
fragments are bridged by an almost perfectly linear C4
unit. The midpoint of the C-C single bond of the C4
bridge lies on a crystallographic center of symmetry, and
therefore, only four halves of the molecule are found in
the unit cell. As a consequence, both P2RhCO planes
(7) (a) Preparation: Uson, R.; Oro, L. A.; Cabeza, J . A. Inorg. Synth.
1985, 23, 126-127. (b) X-ray crystal structure: Selent, D.; Ramm, M.
J . Organomet. Chem. 1995, 485, 135-140.
(8) Gregorio, G.; Pregaglia, G.; Ugo, R. Inorg. Chim. Acta 1969, 3,
89-93.
(11) Werner, H.; Wolf, J .; Garcia Alonso, F. J .; Ziegler, M. L.;
Serhadli, O. J . Organomet. Chem. 1987, 336, 397-411.
(12) For a short review on organometallics with “naked” Cn units,
see: Lang, H. Angew. Chem. 1994, 106, 569-572; Angew. Chem., Int.
Ed. Engl. 1994, 33, 547-550.
(9) Yoshida, T.; Okano, T.; Ueda, Y.; Otsuka, S. J . Am. Chem. Soc.
1981, 103, 3411-3422.
(10) Busetto, C.; D’Alfonso, A.; Maspero, F.; Perego, G.; Zazzetta,
A. J . Chem. Soc., Dalton Trans. 1977, 1828-1834.

2808 Organometallics, Vol. 15, No. 12, 1996
Gevert et al.
lustrated by Alper et al.,5 who prepared [C5H5Rh-
(PPh3)2], [Rh(µ-O2CPh)(PPh3)2], and in particular the
heterobinuclear complexes [(PPh3)2Rh(µ-CO)2M(CO)-
C5H5] (M ) Cr, Mo, W) from [Rh(µ-OH)(PPh3)2]2.
Ta ble 2. Selected Bon d Dista n ces a n d An gles w ith
Esd ’s for Com p ou n d 7
Bond Distances (Å)
Rh-C1
Rh-C3
Rh-P1
2.021(4)
1.832(4)
2.323(2)
Rh-P2
C3-O1
C1-C2
C2-C2*
2.319(2)
1.143(5)
1.205(5)
1.388(7)
Exp er im en ta l Section
Bond Angles (deg)
All reactions were carried out under an atmosphere of argon
by use of Schlenk tube techniques. The starting materials
[RhCl(PiPr3)2]2 (1),4a [RhCl(C8H14)2]2 (3),20 and Me3-
P1-Rh-P2
P1-Rh-C1
P1-Rh-C3
P2-Rh-C1
P2-Rh-C3
175.70(3)
88.6(1)
91.7(1)
87.6(1)
92.2(1)
C1-Rh-C3
Rh-C1-C2
Rh-C3-O1
C1-C2-C2*
177.8(2)
178.5(4)
178.2(4)
178.9(5)
17
SiCtCCtCSnPh3 were prepared as described in the litera-
ture. PhCtCSiMe3 and Me3SiCtCCtCSiMe3 were commer-
cial products from Aldrich and ABCR. NMR spectra were
recorded at room temperature on Varian 360 EM, J eol FX 90
Q, Bruker AC 200, and Bruker AMX 400 instruments, and IR
spectra on a Perkin-Elmer 1420 infrared spectrophotometer.
Melting points were determined by DTA.
a
The midpoint of the bond C2-C2* is a center of symmetry,
and therefore, the corresponding bond distances Rh-C1/Rh*-C1*,
etc., and bond angles P1-Rh-P2/P1*-Rh*-P2*, etc., are identi-
cal.
P r ep a r a tion of [Rh (µ-OH)(P iP r 3)2]2 (2). A solution of 1
(160 mg, 0.17 mmol) in 10 mL of benzene was treated with 5
mL of 20% aqueous NaOH (saturated with argon) and TEBA
(10 mg). Upon stirring of the reaction mixture for 20 min at
room temperature, a change of color from violet to orange
occurred. The organic phase was separated, washed with 5
mL of degassed H2O, and then brought to dryness in vacuo.
After the residue was extracted with 20 mL of pentane and
the solvent removed from the extract, an orange solid was
obtained: yield 123 mg (80%); mp 107 °C dec; 1H NMR (C6D6,
200 MHz) δ 2.00 (m, 6H, PCHCH3), 1.40 [dd, J (PH) ) 11.6,
J (HH) ) 7.3 Hz, 36H, PCHCH3], -2.77 (s, br, 1H, OH); 31P
NMR (C6D6, 81.0 MHz) δ 61.3 [d, J (RhP) ) 183.1 Hz].
P r epar ation of tr a n s-[Rh (OH)(CO)(P iP r 3)2] (4). Meth od
a . A solution of 2 (138 mg, 0.16 mmol) in 5 mL of pentane
was stirred at -78 °C under a CO atmosphere. After 2-3 min
an almost white solid precipitated, which was separated from
the mother liquor, washed three times with 3 mL of pentane
each, and dried: yield 139 mg (95%).
Meth od b. A suspension of 3 (272 mg, 0.38 mmol) in 7 mL
of acetone was treated with PiPr3 (435 µL, 365 mg, 2.28 mmol)
and stirred for 10 min at room temperature. A violet precipi-
tate (consisting of 1) was formed, which was separated from
the solution, washed three times with 3 mL of acetone (0 °C)
each, and then dissolved in 8 mL of benzene. Upon passing
CO through this solution for 10-15 sec, a change of color from
violet to pale yellow occurred. The solution was treated with
KOtBu (0.1 g, 1.0 mmol) and 1 mL of tBuOH and stirred for
16 h at room temperature. Thereafter, 3 mL of degassed H2O
was added, the two phases were separated, and the organic
phase was washed twice with 3 mL of H2O each and then
filtered. The filtrate was brought to dryness in vacuo, and
the residue was repeatedly washed with pentane and dried:
yield 258 mg (72%). Compound 4 was identified by comparison
of the 1H NMR spectrum with published data.9 31P NMR
(C6D6, 36.2 MHz): δ 50.35 [d, J (RhP) ) 136.3 Hz].
F or m a tion of tr a n s-[Rh (CtCP h )(p y)(P iP r 3)2] (5) fr om
2. To a solution of 2 (50 mg, 0.06 mmol) in 0.5 mL of C6D6,
placed in an NMR tube, was added PhCtCSiMe3 (20 µL, 0.10
mmol) and excess of pyridine (ca. 20 µL). After 24 h at room
temperature, the 31P NMR spectrum (36.2 MHz) displayed a
doublett at 41.1 ppm [J (RhP) ) 150.9 Hz] which by comparison
was shown to correspond to 5;11 the yield was nearly quantita-
tive.
F or m a tion of tr a n s-[Rh (CtCP h )(CO)(P iP r 3)2] (6) fr om
2. A solution of 2 (50 mg, 0.06 mmol) in 0.5 mL of C6D6, placed
in an NMR tube, was treated with PhCtCSiMe3 (20 µL, 0.10
mmol) at room temperature. After argon was replaced by CO,
the tube was sealed and stored for 4 h at 40 °C. The 31P NMR
spectrum (36.2 MHz) then displayed a doublet at 53.7 ppm
[J (RhP) ) 126.0 Hz] which by comparison was shown to
correspond to 62 with a yield nearly quantitative.
lie parallel in the crystal and not perpendicular as one
would expect due to the steric demand of the bulky
phosphine groups. Not only the Rh-C1-C2 and C1-
C2-C2* but also the Rh-C-O linkages are nearly
linear while the P1-Rh-P2 axis is slightly bent (see
Table 2). The bond lengths of the RhC4Rh unit are
comparable to those found in ReC4Re13 and RuC4Ru
complexes,14 which have a piano-stool configuration. We
note that besides 7 both cationic15 and neutral16 bi-
nuclear rhodium(III) complexes incorporating a RhC4Rh
linkage are known; however, they contain octahedrally
coordinated Rh(III) centers.
From 4 and Ph3SnCtCCtCSiMe3 as starting materi-
als, the mononuclear diynylmetal complex [Rh-
(CtCCtCSiMe3)(CO)(PiPr3)2] (8) has been prepared.
The silyl-stannyl diyne derivative was obtained via the
lithium compound Me3SiCtCCtCLi,17 which is acces-
sible from Me3SiCtCCtCSiMe3 and 1 equiv of CH3Li.18
In contrast to the 13C NMR spectrum of 7, in which only
two slightly overlapping multiplets for the carbon atoms
of the C4 bridge are observed, the 13C NMR spectrum
of 8 displays four well-separated signals at δ 121.25,
103.0, 93.2, and 77.2 for the carbons of the C4 chain.
The first two of these signals are split into doublets-of-
triplets due to Rh-C and P-C coupling. It should be
mentioned that trans-[Rh(CtCCtCPh)(CO)(PiPr3)2], an
analogue of compound 8, is known and has recently been
synthesized by stepwise treatment of [Rh(η2-CH2C6H5)-
(PiPr3)2] with CO and HCtCCtCPh.19
In summary, we have established a new route for the
preparation of square-planar alkynyl-, diynyl- and
diyndiylrhodium(I) complexes using either the highly
reactive binuclear hydroxo-bridged species 2 or the
corresponding mononuclear carbonyl derivative 4 as
starting materials. The propensity of hydroxorhodium
compounds to react with acidic substrates by forming
new rhodium-element bonds has already been il-
(13) Zhou, Y.; Seyler, J . W.; Weng, W.; Arif, A. M.; Gladysz, J . A. J .
Am. Chem. Soc. 1993, 115, 8509-8510.
(14) Bruce, M. I.; Hinterding, P.; Tiekink, E. R. T.; Skelton, B. W.;
White, A. H. J . Organomet. Chem. 1993, 450, 209-218.
(15) Fyfe, H. B.; Mlekuz, M.; Zargarian, D.; Taylor, N. J .; Marder,
T. B. J . Chem. Soc., Chem. Commun. 1991, 188-190.
(16) Rappert, T.; Nu¨rnberg, O; Werner, H. Organometallics 1993,
12, 1359-1364.
(17) Bre´fort, J . L.; Corriu, R. J . P.; Gerbier, P.; Gue´rin, C.; Henner,
B. J . L.; J ean, A.; Kuhlmann, T.; Garnier, F.; Yassar, A. Organo-
metallics 1992, 11, 2500-2506.
(18) Holmes, A. B.; J ennings-White, C. L. D.; Schulthess, A. H.;
Akinde, B.; Walton, D. R. M. J . Chem. Soc., Chem. Commun. 1979,
840-842.
(19) Werner, H.; Gevert, O.; Steinert, P.; Wolf, J . Organometallics
1995, 14, 1786-1791.
(20) van der Ent, A.; Onderdelinden, A. L. Inorg. Synth. 1973, 14,
92-95.

[Rh(µ-OH)(PiPr3)2]2
Organometallics, Vol. 15, No. 12, 1996 2809
Ta ble 3. Cr ysta llogr a p h ic Da ta for 2 a n d 7
formula
C36H86O2P4Rh2 (2)
880.75
C42H84O2P4Rh2 (7)
950.80
fw
cryst size, mm3
0.48 × 0.43 × 0.55
monoclinic
P21/n (No. 14)
25 reflns, 10° < θ < 16°
13.218(3)
16.275(3)
21.712(3)
104.730(4)
4517(2)
4
0.20 × 0.30 × 0.30
monoclinic
P21/n (No. 14)
25 reflns, 8° < θ < 19°
11.430(9)
17.181(3)
13.012(8)
103.87(3)
cryst syst
space group
cell dimens determn
a, Å
b, Å
c, Å
â, deg
V, Å3
Z
2481(2)
2 (4/2)
d
calcd, g cm-3
1.295
1.273
diffractometer
Enraf Nonius CAD4
radiation (λ, Å)
Mo KR (0.709 30)
filter factor (Zr filter)
temp, °C
16.4
-50(2)
0.890
ω/θ
42
4564
15.4
+20(2)
0.816
ω/θ
50
4558
µ, mm-1
scan method
2θ(max), deg
tot. no. of reflns scanned
no. of unique reflns
no. of obsd reflns [I > 2(I)]
no. of reflns used for refinement
no. of params refined
final R indices [I > 2(I)]
4302 [R(int) ) 0.0426]
3676
4328 [R(int) ) 0.0658]
3588
4294
403
4327
238
R1 ) 0.0258a
wR2 ) 0.0686
R1 ) 0.0408
wR2 ) 0.0836b
10.7
R1 ) 0.0348a
wR2 ) 0.0927
R1 ) 0.0512
wR2 ) 0.1033b
18.2
R indices (all data)
reflns:param ratio
resid electron density, e Å-3
0.386/-0.370
0.790/-0.752
a
b
2
Conventional R-factor: R1 ) ∑|Fo - Fc|/∑Fo [for Fo > 4σ(Fo)]. Weighted R-factor: wR2 ) {∑[w(Fo - Fc2)2]/∑[w(Fo2)2]}1/2, with w-1
) σ2(Fo)2 + 0.0326P2 + 7.1252P (2) and w-1 ) σ2(Fo)2 + 0.0604P2 + 1.042P (7), where P ) (Fo + 2Fc2)/3.
2
P r epar ation of tr a n s,tr a n s-[(P iP r 3)2(CO)Rh (CtCCtC)-
Rh (CO)(P iP r 3)2] (7). A solution of 4 (150 mg, 0.32 mmol) in
3 mL of methanol was treated with Me3SiCtCCtCSiMe3 (31
mg, 0.16 mmol) at room temperature and then heated for 1
min under reflux. After the solution was cooled to room
temperature, the solvent was removed in vacuo, and the
residue was dissolved in 2 mL of acetone. Upon storing of this
solution for 15 h at -78 °C, yellow crystals precipitated, which
were filtered out, washed with 2 mL of acetone (-20 °C), and
dried: yield 115 mg (75%); mp 128 °C dec; IR (KBr) ν(CO) 1934
cm-1, ν(CtC) not exactly located; 1H NMR (C6D6, 400 MHz) δ
2.50 (m, 6H, PCHCH3), 1.36 [dvt, N ) 14.0, J (HH) ) 7.2 Hz,
36H, PCHCH3]; 13C NMR (C6D6, 100.6 MHz) δ 196.0 [dt,
J (RhC) ) 58.4, J (PC) ) 12.6 Hz, RhCO], 109.5, 108.1 (both
m, RhCtC and RhCtC), 26.3 [vt, N ) 22.0 Hz, PCHCH3], 20.6
(s, PCHCH3); 31P NMR (C6D6, 162.0 MHz) δ 54.1 [d, J (RhP) )
128.0 Hz]. Anal. Calcd for C42H84O2P4Rh2: C, 53.05; H, 8.90;
Rh, 21.65. Found: C, 53.06; H 9.17; Rh, 20.61.
δ 53.6 [d, J (RhP) ) 125.2 Hz]. Anal. Calcd for C26H51OP2-
RhSi: C, 54.54; H, 8.98; Rh, 17.97. Found: C, 54.70; H 8.68;
Rh, 18.25.
X-r a y Str u ctu r a l An a lyses of 2 a n d 7. Single crystals
were grown from hexane (2) and toluene (7). Crystal data
collection parameters are summarized in Table 3. Intensity
data were corrected for Lorentz and polarization effects; for 2
a linear decay (loss of gain -6.2%) was taken into consider-
ation. The structures were solved by direct methods (SHELXS-
86). The positions of the hydrogen atoms (with the exception
of O-H) were calculated according to ideal geometry (distance
of C-H set at 0.95 Å) and were refined by the riding method.
Atomic coordinates and anisotropic thermal parameters of the
non-hydrogen atoms were refined by full-matrix least squares
on F2 (SHELXL-93). For other details see Table 3.
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. We also
gratefully acknowledge support by Mrs. A. Spenkuch
and Mr. U. Schmidt (technical assistance), Mrs. R.
Schedl and Mr. C. P. Kneis (elemental analysis and
DTA), Mrs. M. L. Scha¨fer, Mr. B. Stempfle, and Mr. C.
Gru¨nwald (NMR measurements), and Degussa AG
(chemicals).
P r epar ation of tr a n s-[Rh (CtCCtCSiMe3)(CO)(P iP r 3)2]
(8). A solution of 4 (120 mg, 0.26 mmol) in 5 mL of benzene
was treated with Me3SiCtCCtCSnPh3 (123 mg, 0.26 mmol)
at room temperature and then heated for 1-2 min to 80 °C.
After being cooled to room temperature the solution was
worked up as described for 7: yellow microcrystalline solid;
yield 86 mg (58%); mp 64 °C dec; IR (KBr) ν(CtC) 2150, 2105,
ν(CO) 1940 cm-1 1H NMR (C6D6, 400 MHz) δ 2.39 (m, 6H,
;
PCHCH3), 1.21 [dvt, N ) 14.0, J (HH) ) 7.2 Hz, 36H,
PCHCH3], 0.08 (s, 9H, SiMe3); 13C NMR (C6D6, 100.6 MHz) δ
195.9 [dt, J (RhC) ) 72.4, J (PC) ) 13.1 Hz, RhCO], 121.25 [dt,
J (RhC) ) 43.3, J (PC) ) 22.1 Hz, RhCtC], 103.0 [dt, J (RhC)
) 13.1, J (PC) ) 2.5 Hz, RhCtC], 93.2, 77.2 (both s, br,
RhCtCCtC and CSiMe3), 26.3 [vt, N ) 21.6 Hz, PCHCH3],
20.35 (s, PCHCH3), 0.5 (s, SiMe3); 31P NMR (C6D6, 162.0 MHz)
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 2 and 7 (13
pages). Ordering information is given on any current mast-
head page.
OM9601155