ꢀ
P. Smolenski / Journal of Organometallic Chemistry 696 (2011) 3867e3872
3869
1
(121.4 MHz, CDCl3):
NMR (75.4 MHz, CDCl3):
d
ꢁ26.6 (d, JPeRh ¼ 184.3 Hz, PTA). 13C{1H}
242 (100) [RhP(CH2CH2CN)2]þ, 296 (85) [M ꢁ COeind]þ, 358 (42)
[M ꢁ COeCH2]CHCN]þ, 411 (97) [M ꢁ CO]þ, 439 (2) [M]þ. IR (4,
1
d
199.4 (dd, JCeRh
¼
85.3 Hz,
1
2JCeP ¼ 23.0 Hz, CO), 85.3 (d, JCeRh ¼ 4.8 Hz, cp), 74.6 (d,
KBr): 2999, 2982, 2945 (3s br) n(CH), 2240 (s) n(CN), 1945 (s) n(CO),
1JCeP ¼ 15.4 Hz, PCH2N), 58.1 (d, 3JCeP ¼ 5.3 Hz, NCH2N).
1610 (m), 1459 (m), 1427 (m), 1321 (m) 1232 (s), 1002 (s), 955 (s)
904 (s), 767 (s) 737 (s) (P(CH2CH2CN)3 and indenyl bands). 1H NMR
2.3.2. Synthesis of [Rh(
h
5-cp)(CO){P(CH2CH2CN)3}] (2)
5-cp)(CO)2] (224.0 mg, 1.00 mmol)
(300 MHz, CD2Cl2): d
7.22 (m, 2H, H4,7, ind), 7.21 (m, 2H, H5,6, ind),
To a solution (50 mL) of [Rh(
h
6.13 (m, 1H, JHeRh ¼ 2.7 Hz, H2, ind), 5.53 (m, 2H, H1,3, ind), 2.36 (td,
3
in toluene P(CH2CH2CN)3 was added (193.2 mg,1.00 mmol), and the
mixture was refluxed for 6 h. The microcrystalline yellow product
was collected by filtration, washed with cold ethanol (2 ꢂ 10 mL)
and hexane (20 mL) and dried in vacuo. Yield: 2, 52% (202.4 mg)
2JHeP ¼ 12.0 Hz, JHeH ¼ 6.0 Hz, 6H, P(CH2CH2CN)3), 2.10 (td,
3JHeP
¼
3JHeH
¼
6.0 Hz, 6H, P(CH2CH2CN)3). 31P{1H} NMR
(121.4 MHz, CD2Cl2):
(75.4 MHz, CD2Cl2):
d
63.6 (d, 1JPeRh ¼ 202.4 Hz, PTA). 13C{1H} NMR
2
d
193.9 (dd, 1JCeRh ¼ 79.1 Hz, JCeP ¼ 22,9 Hz,
based on [Rh(
h
5-cp)(CO)2]. Complex 2 is soluble in DMSO and
CO), 126.3 (s, C5,6, ind), 120.0 (s, CN), 117.8 (s, C4,7, ind), 115.3 (s,
chloroform, less soluble in MeOH and EtOH, sparingly soluble in
C
C
3a,7a, ind), 92.1 (d, JCeRh ¼ 5.2 Hz, C2, ind), 76.2 (d, JCeRh ¼ 3.1 Hz,
H2O (S25 C z 0.5 mg mLꢁ1) and insoluble in toluene and alkanes. 2,
1,3, ind), 25.9 (d, 1JCeP ¼ 24.5 Hz, PCH2) 12.1 (s, CH2CN).
ꢀ
C15H17N3OPRh (389.20): calcd. C 46.29, H 4.40, N 10.80; found C
46.11, H 4.31, N 10.90. FABþ-MS: m/z (%) ¼ 103 (100) [Rh]þ, 168 (43)
[Rhcp]þ, 308 (40) [M ꢁ COeCH2]CHCN]þ, 333 361(70) [M ꢁ CO]þ,
3. Results and discussion
389(5) [M]þ. IR (2, KBr): 2966, 2952, 2918 (3s br)
n
(CH), 2239 (s)
3.1. Syntheses and characterization
n
(CN),1906 (s) n(CO),1710 (m),1589 (m),1425 (s),1324 (m) 1287 (s),
1075 (s), 1005 (s), 1000 (s), 940 (s) 904 (m), 740 (m), 570 (s)
[Rh(
was prepared by modifying the published procedures [19], via the
reaction of [{Rh(CO)2( -Cl)}2 with cyclopentadienyl thallium,
whereas [Rh(
5-ind)(CO)2] was synthesized by the reaction of
[{Rh(C2H4)2( -Cl)}2] with indenyl lithium, followed by carbonyla-
tion of the formed [Rh(
5-ind)(C2H4)2], using CO at ambient
temperature and pressure [20]. Treatment of [Rh(
5-cp)(CO)2] with
PTA and P(CH2CH2CN)3 affords (Scheme 2) [Rh(
5-cp)(CO)(PTA)] (1)
and [Rh(
5-cp)(CO)(P(CH2CH2CN)3)] (2), respectively, while [Rh(h5
ind)(CO)(PTA)] (3) and [Rh(
5-ind)(CO)(P(CH2CH2CN)3)] (4) are
5-ind)(CO)2] instead of [Rh(h5
h
5-cp)(CO)2] used for syntheses of phosphine complexes
(P(CH2CH2CN)3 and cyclopentadienyl bands) 1H NMR (300 MHz,
2
3
CDCl3):
d
4.91 (s, 5H, cp), 2.72 (td, JHeP ¼ 14.0 Hz, JHeH ¼ 7.0 Hz,
m
3
6H, P(CH2CH2CN)3), 2.16 (td, JHeP
¼
3JHeH
¼
7.0 Hz, 6H,
h
P(CH2CH2CN)3). 31P{1H} NMR (121.4 MHz, CDCl3):
d
40.5 (d,
m
1JPeRh ¼ 197.2 Hz, PTA). 13C{1H} NMR (75.4 MHz, CDCl3):
d
189.4 (dd,
h
1JCeRh ¼ 80.3 Hz, JCeP ¼ 24,9 Hz, CO), 119.2 (s, CN) 86.7 (d,
h
2
1JCeRh ¼ 1.9 Hz, cp) 25.9 (d, 1JCeP ¼ 24,9 Hz, PCH2) 12.5 (s, CH2CN).
h
h
-
2.3.3. Synthesis of [Rh(
h
5-ind)(CO)(PTA)] (3)
h
To an ethanolic solution (20 mL) of [Rh(
h
5-ind)(CO)2] (274.1 mg,
formed in the presence of [Rh(
h
-
1.00 mmol) PTA was added (157 mg, 1.00 mmol) and the mixture
was stirred at room temperature for 15 min. The microcrystalline
dark-yellow product was collected by filtration, washed with cold
ethanol (2 ꢂ 5 mL) and diethyl ether (20 mL) and dried in vacuo.
cp)(CO)2].
Reactivity of [Rh(
is greater in comparison to [Rh(
uted to the flexibility of indenyl ligand to undergo facile h5
coordinative isomerizations known as the indenyl effect [21]. All
the products were isolated as microcrystalline solids in 52e75%
h
5-ind)(CO)2] for the substitution of phosphine
h
5-cp)(CO)2]. This has been attrib-
h3
e
Yield: 3, 85% (342.7 mg) based on [Rh(
h
5-ind)(CO)2]. Complex 3 is
soluble in H2O (S25 z 6 mg mLꢁ1), DMSO and chloroform, less
ꢀ
C
soluble in MeOH and EtOH, and insoluble in C6H6 and alkanes. 3,
C16H19N3OPRh (403.22): calcd. C 47.66, H 4.75, N 10.42; found C
47.22, H 4.80, N 10.50. FABþ-MS: m/z (%) ¼ 218 (100) [Rhind]þ, 259
(27) [M ꢁ COeindeH]þ, 260 (18) [M ꢁ COeind]þ, 375 (46)
[M ꢁ CO]þ, 403 (76) [M]þ. IR (3, KBr): 3015, 2970, 2930 (3s br)
yields, based on [Rh(
h
5-R)(CO)2] (R ¼ cp, ind), and characterized by
IR and 1H, 31P, 13C NMR spectroscopies, FABþ-MS and elemental
analyses. Compounds 1e4 are air stable in the solid state, however
their aqueous solutions are stable only under inert atmosphere.
Complexes bearing PTA (1 and 3) are better soluble in water and
other polar solvents, such as MeCN, Me2SO. Solubility of 2 and 4 in
water and alcohols increases in the presence of a trace amount of
a base such as sodium hydroxide. All compounds are soluble in
medium polarity solvents such as Me2CO, nPrOH, CH2Cl2, CHCl3,
CH2Cl2 and insoluble in non-polar ones such as toluene and hexane.
n
(CH), 1920 (s) n(CO), 1610 (m), 1450 (m), 1421 (m), 1370 (m), 1290
(m) 1241 (m), 1099 (m), 1015 (s), 975, 971 (s), 924 (s), 894 (m), 811
(m), 770 (s), 731 (m), 695 (m) and 581 (m) (PTA and indenyl bands).
1H NMR (300 MHz, CD2Cl2):
d
7.21 (m, 2H, H4,7, ind), 6.95 (m, 2H,
H
5,6, ind), 5.97 (m, 1H, JHeRh ¼ 3.0 Hz, H2, ind), 5.55 (m, 2H, H1,3, ind)
4.47 (s, 6H, NCH2N, PTA), 4.00 (s, 6H, PCH2N, PTA). 31P{1H} NMR
1
(121.4 MHz, CD2Cl2):
d
ꢁ34.0 (d, JPeRh ¼ 190.0 Hz, PTA). 13C{1H}
3.2. Spectroscopy
1
NMR (75.4 MHz, CD2Cl2):
d
201.0 (dd, JCeRh
¼
84.9 Hz,
2JCeP ¼ 24.1 Hz, CO), 124.5 (s, C5,6, ind), 120.0 (s, C4,7, ind), 114.5 (s,
The IR spectra of 1e4 show related features with typical vibra-
tions due to the aromatic rings of indenyl or cyclopentadienyl anion,
PTA or P(CH2CH2CN)3 ligands. The terminal CO ligand in all
complexes is easily identified by its characteristic IR stretch (strong
and sharp bands in the 1903e1945 cmꢁ1 range) which are compa-
rable to those observed in the related complexes [Rh(R)(CO)(PPh3)]
[1957 [22] (R ¼ cp), 1955 [20] (R ¼ ind) cmꢁ1]. On the one hand, the
CO stretching frequencies in the cyclopentadienyl complexes are
lower than those in the indenyl compounds because of less efficient
MeCO back-bonding in indenyl complexes than in cyclopentadienyl
compounds [21]. On the other hand, since all these complexes
contain the same R ligand (R ¼ cp, ind), the differences found in the
CO stretching vibration must derive from the different effects of the
C
C
3a,7a, ind), 96.1 (d, JCeRh ¼ 4.9 Hz, C2, ind), 75.1 (d, JCeRh ¼ 2.9 Hz,
1,3, ind), 75.8 (d, 1JCeP ¼ 15.0 Hz, PCH2N), 58.2 (d, JCeP ¼ 3.1 Hz,
3
NCH2N).
2.3.4. Synthesis of [Rh(
h
5-ind)(CO){P(CH2CH2CN)3}] (4)
5-ind)(CO)2] (274.1 mg,
To a THF solution (50 mL) of [Rh(
h
1.00 mmol) P(CH2CH2CN)3 was added (193.2 mg, 1.00 mmol) and
the mixture was stirred at room temperature for 1 h. The micro-
crystalline, yellow product was collected by filtration, washed with
cold THF (2x10 mL) and pentane (20 mL) and dried in vacuo. Yield:
4, 74% (333.9 mg) based on [Rh(h
5-ind)(CO)2]. Complex 4 is soluble
in DMSO and chloroform, less soluble in EtOH and THF, sparingly
soluble in H2O (S25 C z 0.7 mg mLꢁ1) and insoluble in toluene and
phosphine ligands. Indeed,
increases in the order L ¼ PTA < P(CH2CH2CN)3 < PPh3, revealing
a similar trend to that found for the cone angle ( , deg) [23] of the
n(CO) for such a series of complexes
ꢀ
hexane. 4, C15H17N3OP3Rh (451.15): calcd. C 39.93, H 3.80, N 9.31;
found C 40.01, H 3.80, N 9.09. FABþ-MS: m/z (%) ¼ 218 (95) [Rhind]þ,
q