Reaction of [η5:σ-Me2C(C5H 4)(C2B10H10)]Ru(NH 2Prn)2 with alkynes. Synthesis and structural characterization of ruthenium aminocarbene and enamin

Article abstract of DOI:10.1021/om060249a

Syntheses of ruthenium aminocarbene and enamine complexes were achieved by tuning the electronic properties of alkynes. Reaction of [η⁵: σ-Me₂C(C₅H₄)(C₂B ₁₀H₁₀)]Ru(NH₂

Full text of DOI:10.1021/om060249a

Organometallics 2006, 25, 3447-3453
3447
Reaction of [η5:σ-Me2C(C5H4)(C2B10H10)]Ru(NH2Prn)2 with Alkynes.
Synthesis and Structural Characterization of Ruthenium
Aminocarbene and Enamine Complexes
Yi Sun, Hoi-Shan Chan, and Zuowei Xie*
Department of Chemistry, The Chinese UniVersity of Hong Kong, Shatin, New Territories,
Hong Kong, China
ReceiVed March 20, 2006
Syntheses of ruthenium aminocarbene and enamine complexes were achieved by tuning the electronic
properties of alkynes. Reaction of [η5:σ-Me2C(C5H4)(C2B10H10)]Ru(NH2Prn)2 (1) with 2 equiv of
phenylacetylene gave the aminocarbene [η5:σ-Me2C(C5H4)(C2B10H10)]Ru[dC(NHPrn)CH(Ph)-η2-CHd
CHPh] (2a) in 45% isolated yield in CH2Cl2 and the enamine complex [η5:σ-Me2C(C5H4)(C2B10H10)]-
Ru[η4-CH(Ph)dC(NHPrn)CHdCHPh] (2b) in 30% isolated yield in toluene. Treatment of 1 with the
electron-rich alkynes 4-ethynyltoluene and 1-hexyne produced only the aminocarbene complexes [η5:σ-
Me2C(C5H4)(C2B10H10)]Ru[dC(NHPrn)CH(p-tolyl)-η2-CHdCH(p-tolyl)] (3a) and [η5:σ-Me2C(C5H4)-
(C2B10H10)]Ru[dC(NHPrn)CH(Bun)-η2-CHdCH(Bun)] (4a), regardless of the solvents used. In contrast,
the reaction of 1 with the electron-deficient alkynes 1-chloro-4-ethynylbenzene and 1-bromo-4-
ethynylbenzene afforded only the enamine complexes [η5:σ-Me2C(C5H4)(C2B10H10)]Ru[η4-CH(XC6H4)d
C(NHPrn)CHdCH(XC6H4)] (X ) Cl (5b), Br (6b)). All complexes were fully characterized by various
spectroscopic techniques and elemental analyses. Their molecular structures (except for 4a) were further
confirmed by single-crystal X-ray analyses.
Scheme 1
Introduction
The chemistry of Ru vinylidene complexes has become
increasingly attractive over the past decades, because it has been
disclosed that the catalytic organic transformation of terminal
alkynes often proceeds via a vinylidene intermediate.1 Typical
examples of such catalytic reactions include the dimerization
of alkynes2 and the addition of nucleophiles to alkynes.3 The
reactivity of metal vinylidene complexes has been well studied
in order to understand the reaction mechanism and to develop
new catalytic reactions.1-3 It has been documented that Rud
CRdCHR contains an electrophilic R-carbon atom which readily
reacts with nucleophiles to form either stable metal carbenes
or reactive metal alkenyls (Scheme 1).1g These two types of
metal complexes are very different in reactivity. Thus, the
question arises as to what factor controls these nucleophilic
reactions. In the course of our studies on the reaction of [η5:
σ-Me2C(C5H4)(C2B10H10)]Ru(NH2Prn)2 with alkynes, we found
that the electronic properties of the alkynes dominate the product
of the reactions. Electron-rich alkynes favor the formation of
Ru carbene complexes, whereas electron-deficient alkynes result
in the formation of Ru alkenyl intermediates. These new findings
are reported in this article.
* To whom correspondence should be addressed. Fax: (852)26035057.
Tel: (852)26096269. E-mail: zxie@cuhk.edu.hk.
(1) For reviews, see: (a) Bruce, M. I.; Swincer, A. G. AdV. Organomet.
Chem. 1983, 22, 59. (b) Antonova, A. B.; Ioganson, A. A.; Khim, U. Russ.
Chem. ReV. 1989, 58, 1197. (c) Bruce, M. I. Chem. ReV. 1991, 91, 197. (d)
Werner, H. J. Organomet. Chem. 1994, 475, 45. (e) Werner, H. Chem.
Commun. 1997, 903. (f) Bruce, M. I. Chem. ReV. 1998, 98, 2797. (g)
Bruneau, C.; Dixneuf, P. H. Acc. Chem. Res. 1999, 32, 311. (h) Slugovc,
C.; Schmid, R.; Kirchner, K. Coord. Chem. ReV. 1999, 185/186, 109. (i)
Yi, C. S.; Liu, N. Synlett 1999, 281. (j) Trost, B. M. Acc. Chem. Res. 2002,
35, 695. (k) Ritleng, V.; Sirlin, C.; Pfeffer, M. Chem. ReV. 2002, 102, 1731.
(l) Grubbs, R. H. Handbook of Metathesis; Wiley-VCH: Weinheim,
Germany, 2003. (m) Katayama, H.; Ozawa, F. Coord. Chem. ReV. 2004,
248, 1703. (n) Bruneau, C. Top. Organomet. Chem. 2004, 11, 125. (o)
Rigaut, S.; Touchard, D.; Dixneuf, P. H. Coord. Chem. ReV. 2004, 248,
1585. (p) Cadierno, V.; Gamasa, M. P.; Gimeno, J. Coord. Chem. ReV.
2004, 248, 1627. (q) Werner, H. Coord. Chem. ReV. 2004, 248, 1693. (r)
Valyaev, D. A.; Semeikin, O. V.; Ustynyuk, N. A. Coord. Chem. ReV. 2004,
248, 1679. (s) Selegue, J. P. Coord. Chem. ReV. 2004, 248, 1543. (t) Bruce,
M. I. Coord. Chem. ReV. 2004, 248, 1603. (u) Herndon, J. W. Coord. Chem.
ReV. 2004, 248, 3. (v) Miki, K.; Uemura, S.; Ohe, K. Chem. Lett. 2005, 34,
1068. (w) Bruneau, C.; Dixneuf, P. H. Angew. Chem., Int. Ed. 2006, 45,
2176.
Results
Synthesis. Ruthenium vinylidene complexes can be directly
prepared from the reactions of LRu(COD) or LRu(PPh3)2 (L )
(3) For example, see: (a) Gamasa, M. P.; Gimeno, J.; Lastra, E.;
Lanfranchi, M.; Tiripicchio, A. J. Organomet. Chem. 1992, 430, C39. (b)
Bianchini, C.; Glendenning, L.; Peruzzini, M.; Romerosa, A.; Zanobini, F.
J. Chem. Soc., Chem. Commun. 1994, 2219. (c) Bianchini, C.; Marchi, A.;
Marvelli, L.; Peruzzini, M.; Romerosa, A.; Rossi, R. Organometallics 1996,
15, 3804. (d) Ting, P.-C.; Lin, Y.-C.; Lee, G.-H.; Cheng, M.-C.; Wang, Y.
J. Am. Chem. Soc. 1996, 118, 6433. (e) Bianchini, C.; Masi, D.; Romerosa,
A.; Zanobini, F.; Peruzzini, M. Organometallics 1999, 18, 2376. (f) Buil,
M. L.; Esteruelas, M. A.; Lopez, A. M.; Onate, E. Organometallics 2003,
22, 162. (g) Buil, M. L.; Esteruelas, M. A.; Lopez, A. M.; Onate, E.
Organometallics 2003, 22, 5274. (h) Cadierno, V.; Garc´ıa-AÄ lvarez, J.;
Gimeno, J.; Rubio-Garc´ıa, J. J. Organomet. Chem. 2005, 690, 5856. (i)
D´ıez, J.; Gamasa, M. P.; Gimeno, J.; Lastra, E.; Villar, A. Eur. J. Inorg.
Chem. 2006, 78. (j) Bruce, M. I.; Kramarczuk, K. A.; Skelton, B. W.; White,
A. H.; Zaitseva, N. N. Inorg. Chim. Acta 2006, 359, 938.
(2) For example, see: (a) Saoud, M.; Romerosa, A.; Peruzzini, M.
Organometallics 2000, 19, 4005. (b) Opstal, T.; Verpoort, F. Synlett 2003,
314. (c) Chen, X.; Xue, P.; Sung, H. H. Y.; Williams, I. D.; Peruzzini, M.;
Bianchini, C.; Jia, G. Organometallics 2005, 24, 4330. (d) Katayama, H.;
Yari, H.; Tanaka, M.; Ozawa, F. Chem. Commun. 2005, 4336.
10.1021/om060249a CCC: $33.50 © 2006 American Chemical Society
Publication on Web 06/10/2006

3448 Organometallics, Vol. 25, No. 14, 2006
Sun et al.
Scheme 2
Scheme 3
Scheme 4
any significant differences in the 11B NMR spectra, displaying
a 1:1:2:6 pattern. It is noteworthy that the molar ratio of the
two pairs of diastereomers (4:3) did not change upon heating
the NMR solution close to the boiling point of C6D6, suggesting
that epimerization did not proceed under these conditions.
In contrast, the 1H NMR spectrum of 2b was relatively
simple. The characteristic resonances were two doublets at 5.54
cyclopentadienyl and its derivatives) with alkynes.4 Since [η5:
σ-Me2C(C5H4)(C2B10H10)]Ru(COD) is inert to alkynes5 and [η5:
σ-Me2C(C5H4)(C2B10H10)]Ru(PPh3)2 is not feasible,6a [η5:σ-
Me2C(C5H4)(C2B10H10)]Ru(NH2Prn)2 (1)6b was then chosen as
the starting material. Treatment of 1 with 2 equiv of phenyl-
acetylene in CH2Cl2 afforded both the ruthenium aminocarbene
[η5:σ-Me2C(C5H4)(C2B10H10)]Ru[dC(NHPrn)CH(Ph)-η2-CHd
CHPh] (2a) and the ruthenium enamine [η5:σ-Me2C(C5H4)-
(C2B10H10)]Ru[η4-CH(Ph)dC(NHPrn)CHdCHPh] (2b) in a
3
and 1.73 ppm with J ) 8.1 Hz attributable to PhCHddCHe
protons, one singlet at 3.61 ppm assignable to the PhCHfdC
proton, and two singlets at 1.45 and 1.30 ppm corresponding
to the Me2C protons. The very high field chemical shift of the
olefinic proton can be ascribed to the back-bonding effect of
the Ru d electrons to the CdC bond, which was previously
described in the literature.9 The 13C NMR spectrum of 2b was
consistent with its 1H NMR data. No carbene carbon was
observed.
1
molar ratio of 76:24, as measured by the H NMR spectrum
(Scheme 2). Recrystallization from toluene gave 2a as yellow
crystals in 45% isolated yield. If the reaction solvent was
switched from CH2Cl2 to toluene, the molar ratio of 2a to 2b
was accordingly changed to 32:68. Recrystallization from
toluene produced 2b as yellow crystals in 30% isolated yield.
Both 2a and 2b are reasonably stable in air in the solid state.
The 1H NMR spectrum of 2a showed that it existed in C6D6
solution as a 4:3 mixture of two diastereomerically related pairs
of enantiomers, RR, SS and RS, SR, due to the presence of two
chiral centers,7 C* and Ru*, shown in Scheme 2. The charac-
teristic PhCHadCHbCHcPh protons were observed as two
doublets and one doublet of doublets at 4.87, 3.43, and 4.37
ppm for the major pair of diastereomers and at 4.45, 3.69, and
4.03 ppm for another pair, respectively. Two sets of Me2C
protons were also observed as singlets at 1.29 and 1.17 ppm
for one pair and 1.29 and 1.07 ppm for the other pair. In the
13C NMR spectrum, two sets of signals corresponding to the
two pairs of diastereomers were again found. In particular, the
unique RudC carbon chemical shift was observed at 250.6 and
241.7 ppm, respectively.3e,8 These diastereomers did not show
The above results indicated that the solvent effect was
important in the reaction of 1 with PhCtCH. We wondered if
this phenomenon would be observed in other terminal alkynes.
Reaction of 1 with 2 equiv of the electron-rich alkynes
4-ethynyltoluene and 1-hexyne gave the ruthenium aminocar-
bene complexes [η5:σ-Me2C(C5H4)(C2B10H10)]Ru[dC(NHPrn)-
CH(p-tolyl)-η2-CHdCH(p-tolyl)] (3a) and [η5:σ-Me2C(C5H4)-
(C2B10H10)]Ru[dC(NHPrn)CH(Bun)-η2-CHdCH(Bun)] (4a) in
63% and 71% isolated yields, respectively, regardless of the
solvent used in the reaction, CH2Cl2 or toluene (Scheme 3).
1
No ruthenium enamine complexes were detected by the H
NMR. On the other hand, interaction of 1 with 2 equiv of the
electron-deficient alkynes 1-halo-4-ethynylbenzene pro-
duced exclusively the ruthenium enamine complexes [η5:σ-
Me2C(C5H4)(C2B10H10)]Ru[η4-CH(XC6H4)dC(NHPrn)-
CHdCH(XC6H4)] (X ) Cl (5b), Br (6b)) in good isolated yields
1
(Scheme 4). No solvent effect was observed by the H NMR
experiments.
(4) For example, see: (a) Wakatsuki, Y.; Koga, N.; Yamazaki, H.;
Morokuma, K. J. Am. Chem. Soc. 1994, 116, 8105. (b) Yi, C. S.; Liu, N.;
Rheingold, A. L.; Liable-Sands, L. M.; Guzei, I. A. Organometallics 1997,
16, 3729.
(5) Sun, Y.; Chan, H.-S.; Dixneuf, P. H.; Xie, Z. Organometallics 2004,
23, 5864.
(6) (a) Sun, Y.; Chan, H.-S.; Dixneuf, P. H.; Xie, Z. Chem. Commun.
2004, 2588. (b) Sun, Y.; Chan, H.-S.; Dixneuf, P. H.; Xie, Z. J. Organomet.
Chem. 2006, 691, 3071.
(7) (a) Brunner, H. Angew. Chem., Int. Ed. 1999, 38, 1194. (b) Consiglio,
G.; Morandini, F. Chem. ReV. 1987, 87, 761. (c) Killops, S. D.; Knox, S.
A. R.; Riding, G. H.; Welch, A. J. J. Chem. Soc., Chem. Commun. 1978,
486. (d) Dersnah, D. F.; Baird, M. C. J. Organomet. Chem. 1977, 127,
C55.
As for 2a, the NMR spectra of 3a and 4a indicated that they
existed in solution as 2:1 and 7:3 mixtures of two diastereo-
merically related pairs of enantiomers, respectively. The NMR
spectra of 5b and 6b were very similar to that of 2b.
Structure. Single-crystal X-ray analyses revealed that 2a and
3a have similar solid-state structures, although they crystallized
in different space groups. The Ru atom is η5 bound to the Cp,
η2 bound to the CdC double bond, and σ bound to one of the
cage carbons and one carbene moiety in a three-legged piano-
(9) (a) Fiedler, D.; Leung, D. H.; Bergman, R. G.; Raymond, K. N. J.
Am. Chem. Soc. 2004, 126, 3674. (b) Onitsuka, K.; Nishii, M.; Matsushima,
Y.; Takahashi, S. Organometallics 2004, 23, 5630.
(8) Baratta, W.; Dal Zotto, A.; Herdtweck, E.; Vuano, S.; Rigo, P. J.
Organomet. Chem. 2001, 617/618, 511.

Ruthenium Aminocarbene and Enamine Complexes
Organometallics, Vol. 25, No. 14, 2006 3449
Table 1. Selected Bond Lengths (Å) and Angles (deg) for 2a
and 3aa
2a
3a
Ru-Ccage
2.131(5)
2.217(7)
1.863y
2.156(4)
2.243(5)
1.886
Ru-Cring (av)
Ru-Cent
Ru-C(36)
1.953(8)
2.275(5)
2.171(6)
2.223(6)
1.306(10)
1.505(11)
1.517(10)
1.390(8)
1.952(5)
2.264(4)
2.184(4)
2.224(4)
1.325(6)
1.504(6)
1.543(6)
1.398(6)
Ru-C(27)
Ru-C(28)
Ru-Cvinyl (av)
C(36)-N(1)
C(36)-C(29)
C(29)-C(28)
C(28)-C(27)
C(14)-C(11)-C(1)
Cent-Ru-Ccage
108.4(5)
113.6
132.5(8)
103.1(5)
123.6(9)
96.7(5)
108.9(3)
113.6
131.1(4)
105.2(3)
123.3(5)
95.1(3)
Ru-C(36)-N(1)
Ru-C(36)-C(29)
N(1)-C(36)-C(29)
C(36)-C(29)-C(28)
C(29)-C(28)-C(27)
C(28)-C(27)-C(21)
118.8(5)
122.5(5)
121.4(4)
124.5(4)
a In this table and in Table 2, Cent ) the centroid of the five-membered
ring.
Figure 1. Molecular structure of [η5:σ-Me2C(C5H4)(C2B10H10)]-
Ru[dC(NHPrn)CH(Ph)-η2-CHdCHPh] (2a).
Chart 1
Figure 2. Molecular structure of [η5:σ-Me2C(C5H4)(C2B10H10)]-
Ru[dC(NHPrn)CH(p-tolyl)-η2-CHdCH(p-tolyl)] (3a).
stool geometry, as shown in Figures 1 and 2, respectively.
Selected bond distances and angles are given in Table 1. The
average Ru-C5 ring distances of 2.217(7) Å in 2a and 2.243-
(5) Å in 3a and Ru-C(cage) distances of 2.131(5) Å in 2a and
2.156(4) Å in 3a are very close to the corresponding values
found in [η5:σ-Me2C(C5H4)(C2B10H10)]Ru(L2) (L2 ) amines,
CH3CN, phosphites, phosphines) (I in Chart 1) complexes.5,6b
The RudC(36)/N(1)-C(36) distances of 1.953(8)/1.306(10) Å
in 2a and 1.952(5)/1.325(6) Å in 3a are similar to those observed
in other ruthenium aminocarbene complexes: for example,
1.956(6)/1.349(7) Å in fac,cis-[(PNP)RuCl{C(NHC4H3N2O2)(CH2-
Ph)}]Cl (PNP ) CH3CH2CH2N(CH2CH2PPh2)2) (II in Chart
1),10a 1.915(1)/1.359(1) Å in TpRu(dCCH2C6H9-apic)Cl (Tp
) [HB(pyrazolyl)3]-, apic ) 2-amino-4-picoline) (III in Chart
1),10b and 1.984(12)/1.352(14) Å in CpRu[dC(CH2Ph)NHPh]-
(PPh2NHPh)[κ1(P)-OdPPh2] (IV in Chart 1).10c An observed
substantial N(1)-C(36) double-bond character is a structural
feature of Fischer-type aminocarbenes, which can be ascribed
+
to the resonance RudC-NR2 T Ru--CdNR2
.
X-ray diffraction studies indicated that 2b, 5b, and 6b are
isostructural, in which the Ru atom is η5 bound to the Cp, η4
bound to the butadiene moiety, and σ bound to one of the cage
(10) (a) Fillaut, J.-L.; de los Rios, I.; Masi, D.; Romerosa, A.; Zanobini,
F.; Peruzzini, M. Eur. J. Inorg. Chem. 2002, 935. (b) Ru¨ba, E.; Hummel,
A.; Mereiter, K.; Schmid, R.; Kirchner, K. Organometallics 2002, 21, 4955.
(c) Pavlik, S.; Mereiter, K.; Puchberger, M.; Kirchner, K. Organometallics
2005, 24, 3561.

3450 Organometallics, Vol. 25, No. 14, 2006
Sun et al.
Table 2. Selected Bond Lengths (Å) and Angles (deg) for 2b,
5b, and 6b
2b
5b
6b
Ru-Ccage
2.181(6)
2.210(7)
1.848
2.179(6)
2.226(6)
1.862
2.182(5)
2.228(6)
1.867
Ru-Cring (av)
Ru-Cent
Ru-C(21)
2.206(6)
2.160(7)
2.296(7)
2.225(6)
2.222(7)
1.428(10)
1.424(10)
1.414(10)
1.376(10)
2.249(6)
2.190(7)
2.316(6)
2.258(6)
2.253(7)
1.442(9)
1.412(10)
1.458(10)
1.381(9)
2.229(5)
2.186(5)
2.290(5)
2.228(5)
2.233(5)
1.449(8)
1.436(8)
1.440(8)
1.371(7)
Ru-C(28)
Ru-C(29)
Ru-C(30)
Ru-Cvinyl (av)
C(21)-C(28)
C(28)-C(29)
C(29)-C(30)
C(29)-N(1)
Figure 3. Molecular structure of [η5:σ-Me2C(C5H4)(C2B10H10)]-
Ru[η4-CH(Ph)dC(NHPrn)CHdCHPh] (2b) (the solvated toluene
molecule is not shown).
C(14)-C(11)-C(1)
Cent-Ru-Ccage
107.7(5)
111.7
108.4(5)
112.2
108.1(4)
111.9
C(22)-C(21)-C(28)
C(21)-C(28)-C(29)
C(28)-C(29)-C(30)
C(29)-C(30)-C(31)
C(30)-C(29)-N(1)
C(28)-C(29)-N(1)
119.4(7)
122.5(7)
116.5(6)
119.6(6)
122.4(7)
120.6(8)
121.9(6)
122.8(6)
118.0(6)
122.0(6)
121.0(6)
120.5(7)
120.8(5)
120.4(5)
117.5(5)
121.4(5)
122.2(5)
119.8(6)
Chart 2
[CpRu(η4-C4H3(CH2)3-PPh2-κ1N-NPh)][PF6] (VII in Chart 1),11b
and 2.195(2) Å in [Ru(η5-C5H4CH2CH2PPh2-κ1C-CH-η4-C5-
Ph3H2)][PF6] (VIII in Chart 1).11c The bond distances of C(21)-
C(28)/C(28)-C(29)/C(29)-C(30) are very similar and are
between the typical single- and double-bond distances, sugges-
tive of electron delocalization over four atoms. This phenomenon
has often been observed in Ru butadiene complexes: for
example, 1.399(5), 1.436(5), and 1.381(6) Å in µ-(s-cis-1,2,3,4-
η:s-cis-5,6,7,8-η-PhCHdCHCHdCHCHdCHCHdCHPh)-
(RuClCp*)2 (V in Chart 1),11a 1.416(4), 1.427(4), and 1.406(6)
Å in [CpRu(η4-C4H3(n-Bu)2-PPh2-κ1N-NPh)][PF6] (VI in Chart
1),11b 1.426(5), 1.436(6), and 1.408(6) Å in [CpRu(η4-C4H3-
(CH2)3-PPh2-κ1N-NPh)][PF6] (VII in Chart 1),11b and 1.409-
(2), 1.434(3), and 1.416(2) Å in [Ru(η5-C5H4CH2CH2PPh2-κ1C-
CH-η4-C5Ph3H2)]PF6 (VIII in Chart 1).11c
Figure 4. Molecular structure of [η5:σ-Me2C(C5H4)(C2B10H10)]-
Ru[η4-CH(ClC6H4)dC(NHPrn)CHdCH(ClC6H4)] (5b).
Discussion
The above experimental results indicated that a strong solvent
effect was observed only in the reaction of 1 with PhCtCH.
Although no solvent effect was observed in the reaction of 1
with other alkynes, a significant electronic effect was found.
Alkynes that are more electron rich than PhCtCH gave
ruthenium aminocarbene complexes, whereas those that are
more electron deficient than PhCtCH gave ruthenium enamine
complexes. Subsequently, a question arises as to how these
complexes were formed. One possible pathway may involve
1,3-disubstituted ruthenacyclopentatriene intermediates (IX in
Chart 2), followed by nucleophilic attack of amine at the
unsubstituted R-position to form ruthenium aminocarbene
products, which is similar to the attack of phosphines at the
Figure 5. Molecular structure of [η5:σ-Me2C(C5H4)(C2B10H10)]-
Ru[η4-CH(BrC6H4)dC(NHPrn)CHdCH(BrC6H4)] (6b) (the sol-
vated toluene molecule is not shown).
carbons in a three-legged piano-stool geometry. Their structures
are shown in Figures 3-5. As indicated in Table 2, the key
structural parameters around the Ru atom in 2b, 5b, and 6b are
almost identical. The average Ru-C5 ring and Ru-C(cage)
distances are almost the same as those observed in 2a and 3a.
The Ru-C(21,28,29,30) distances fall in a very narrow range
with an average value of 2.222(7) Å in 2b, 2.253(7) Å in 5b,
and 2.237(5) Å in 6b, which are very close to those of 2.223-
(6) Å in 2a, 2.224(4) Å in 3a, 2.219(4) Å in µ-(s-cis-1,2,3,4-
η:s-cis-5,6,7,8-η-PhCHdCHCHdCHCHdCHCHdCHPh)-
(RuClCp*)2 (V in Chart 1),11a 2.218(3) Å in [CpRu(η4-C4H3-
(n-Bu)2-PPh2-κ1N-NPh)][PF6] (VI in Chart 1),11b 2.221(3) Å in
(11) (a) Mashima, K.; Fukumoto, H.; Tani, K.; Haga, M.; Nakamura,
A. Organometallics 1998, 17, 410. (b) Pavlik, S.; Mereiter, K.; Schmid,
R.; Kirchner, K. Organometallics 2003, 22, 1771. (c) Becker, E.; Mereiter,
K.; Puchberger, M.; Schmid, R.; Kirchner, K.; Doppiu, A.; Salzer, A.
Organometallics 2003, 22, 3164.

Ruthenium Aminocarbene and Enamine Complexes
Organometallics, Vol. 25, No. 14, 2006 3451
Scheme 5
R-position of the 1,3-disubstituted ruthenacyclopentatriene, as
documented in the literature.12 However, the formation of
ruthenium enamine complexes in which the two aryl substituents
are in 1,4-positions is very unlikely via ruthenacyclopentatriene
intermediates, since the R,R′-diaryl-substituted ruthenacyclo-
pentatriene complex does not undergo a nucleophilic reaction
with amine but, rather, gives the amine-coordinated ruthena-
cyclopentadiene (X in Chart 2).13 Given this, the formation of
ruthenium enamine complexes should undergo another pathway.
We have very recently isolated and fully characterized the
ruthenium vinylvinylidene complex [η5:σ-Me2C(C5H4)(C2B10H10)]-
Ru[dCdC(SiMe3)CHdCH(SiMe3)], stabilized by another [η5:
σ-Me2C(C5H4)(C2B10H10)]Ru moiety from the reaction of [η5:
σ-Me2C(C5H4)(C2B10H10)]Ru(NCCH3)2 with excess Me3SiCt
CH.14 The formation of this complex is suggested to involve
the (vinylidene)ruthenium intermediate [η5:σ-Me2C(C5H4)-
(C2B10H10)]Ru[dCdCH(SiMe3)], followed by [2 + 2] cycload-
dition and a ring-opening reaction. The sterically demanding
σ-ligand carboranyl may prevent the formation of a disubstituted
ruthenacyclopentatriene intermediate and makes the coupling
products different from those obtained via the reaction of
CpRuX(L) (L ) COD, (CH3CN)2; X ) Cl, Br, BF4) with RCt
CH.15 In this connection and with respect to the formation of
2a,b in the same reaction, it is reasonable to suggest that the
formation of ruthenium aminocarbene and enamine complexes
is unlikely via ruthenacyclopentatriene intermediates. A stepwise
mechanism is then proposed, as shown in Scheme 5.
Reaction of RCtCH with 1 generates the common (vi-
nylidene)ruthenium intermediate A. In the presence of electron-
rich alkynes, it reacts with A via [2 + 2] cycloaddition followed
by ring-opening reactions to afford the (vinylvinylidene)-
ruthenium intermediate B, similar to [η5:σ-Me2C(C5H4)-
(C2B10H10)]Ru[dCdC(SiMe3)CHdCH(SiMe3)].14 Nucleophilic
attack of the primary amine on the electrophilic R-C of B
produces the final products, ruthenium aminocarbene complexes.
On the other hand, in the presence of electron-deficient alkynes,
nucleophilic attack of the primary amine at RudC of A gives
the alkenylruthenium intermediate C.9b,16 Addition of alkynes
into the Ru-C bond yields the intermediate D, followed by
reductive elimination to afford the final ruthenium enamine
complexes. Electronic effects on the reaction pathway are not
clear.
Experimental Section
General Procedures. All experiments were performed under an
atmosphere of dry dinitrogen with the rigid exclusion of air and
moisture using standard Schlenk or cannula techniques, or in a
glovebox. Toluene and n-hexane were freshly distilled from sodium
benzophenone ketyl immediately prior to use. CH2Cl2 was freshly
distilled from CaH2 and P2O5, respectively, immediately prior to
use. [η5:σ-Me2C(C5H4)(C2B10H10)]Ru(NH2Prn)2 was prepared ac-
cording to literature methods.6b All other chemicals were purchased
from either Aldrich or Acros Chemical Co. and used as received
unless otherwise noted. Infrared spectra were obtained from KBr
pellets prepared in the glovebox on a Perkin-Elmer 1600 Fourier
1
transform spectrometer. H and 13C NMR spectra were recorded
(12) (a) Mauthner, K.; Soldouzi, K. M.; Mereiter, K.; Schmid, R.;
Kirchner, K. Organometallics 1999, 18, 4681. (b) Ru¨ba, E.; Mereiter, K.;
Schmid, R.; Kirchner, K. Chem. Commun. 2001, 1996. (c) Ru¨ba, E.;
Mereiter, K.; Schmid, R.; Kirchner, K.; Schottenberger, H. J. Organomet.
Chem. 2001, 637/639, 70. (d) Becker, E.; Ru¨ba, E.; Mereiter, K.; Schmid,
R.; Kirchner, K. Organometallics 2001, 20, 3851. (e) Ru¨ba, E.; Mereiter,
K.; Schmid, R.; Sapunov, V. N.; Kirchner, K.; Schottenberger, H.; Calhorda,
M. J.; Veiros, L. F. Chem. Eur. J. 2002, 8, 3948. (f) Becker, E.; Mereiter,
K.; Puchberger, M.; Schmid, R.; Kirchner, K. Organometallics 2003, 22,
2124.
(13) Albers, M. O.; De Waal, D. J. A.; Liles, D. C.; Robinson, D. J.;
Singleton, E.; Wiege, M. B. J. Chem. Soc., Chem. Commun. 1986, 1680.
(14) Sun, Y.; Chan, H.-S.; Dixneuf, P. H.; Xie, Z. Organometallics 2006,
25, 2719.
(15) (a) Gemel, C.; LaPense´e, A.; Mauthner, K.; Mereiter, K.; Schmid,
R.; Kirchner, K. Monatsh. Chem. 1997, 128, 1189. (b) Pu, L.; Hasegawa,
T.; Parkin, S.; Taube, H. J. Am. Chem. Soc. 1992, 114, 2712. (c) Hirpo,
W.; Curtis, M. D. J. Am. Chem. Soc. 1988, 110, 5218. (d) Kerschner, J. L.;
Fanwick, P. E.; Rothwell, I. P. J. Am. Chem. Soc. 1988, 110, 8235. (e)
Hessen, B.; Meetsma, A.; Van Bolhuis, F.; Teuben, J. H.; Helgesson, G.;
Jagner, S. Organometallics 1990, 9, 1925. (f) Ernst, C.; Walter, O.; Dinjus,
E.; Arzberger, S.; Go¨rls, H. J. Prakt. Chem. 1999, 341, 801. (g) Yamada,
Y.; Mizutani, J.; Kurihara, M.; Nishihara, H. J. Organomet. Chem. 2001,
637/639, 80.
on a Bruker DPX 300 spectrometer at 300 and 75 MHz, respec-
tively. 11B NMR spectra were recorded on a Varian Inova 400
spectrometer at 128 MHz. All chemical shifts were reported in δ
units with reference to the residual solvent resonance of the
deuterated solvents for proton and carbon chemical shifts and to
external BF3‚OEt2 (0.0 ppm) for boron chemical shifts. Elemental
analyses were performed by MEDAC Ltd., Egham, Surrey, U.K.,
or the Shanghai Institute of Organic Chemistry, CAS, Shanghai,
People’s Republic of China. Melting points were determined on
an Electrothermal M-IA9100 digital melting point apparatus and
were uncorrected.
Preparation of [η5:σ-Me2C(C5H4)(C2B10H10)]Ru[dC(NHPrn)-
CH(Ph)-η2-CHdCHPh] (2a). Phenylacetylene (44 µL, 0.40 mmol)
was added via microsyringe to a CH2Cl2 solution (5 mL) of [η5:
σ-Me2C(C5H4)(C2B10H10)]Ru(NH2Prn)2 (1; 88 mg, 0.20 mmol) at
0 °C; the mixture was then warmed to room temperature and stirred
for 2 days to give a brown solution. After removal of CH2Cl2, the
resulting solid was washed with n-hexane. The 1H NMR spectrum
indicated that this solid was a mixture of 2a and 2b in a molar
ratio of 76:24. Recrystallization from toluene gave 2a as yellow
crystals (56 mg, 45%), mp 172.5 °C. IR (KBr, cm-1): ν 3420 (m)
(16) Addition of phosphines into RudC of (vinylidene)ruthenium
complexes were reported; see ref 9b and: Je´roˆme, F.; Monnier, F.; Lawicka,
H.; De´rien, S.; Dixneuf, P. H. Chem. Commun. 2003, 696.

3452 Organometallics, Vol. 25, No. 14, 2006
Sun et al.
(NH), 2562 (vs) (BH). 11B{1H} NMR (C6D6): δ -2.6 (1B), -4.4
(1B), -6.2 (2B), -8.3 (6B). 13C{1H} NMR (C6D6): δ 250.6 241.7
(RudC), 144.8, 144.1, 140.6, 139.6, 136.8, 134.2, 129.4, 127.3,
125.7, 125.5, 125.3, 125.0 (aryl C), 88.6, 87.9, 87.1, 83.5, 82.5,
80.2, 78.5, 76.4, 74.8, 74.5, 71.9, 62.9 (CHa/b and C5H4), 52.3, 51.3
(NHCH2), 44.9, 42.1 (CHc), 41.2, 40.8 (C(CH3)2), 32.3, 31.2 30.2
(C(CH3)2), 22.6, 22.2 (CH2CH3), 11.3, 10.9 (CH2CH3); cage carbons
were not observed. For the major pair of diastereomers: 1H NMR
(C6D6) δ 7.99 (br s, 1H, NH), 7.33-6.81 (m, 10H, C6H5), 4.87 (d,
3J ) 9.9 Hz, 1H, PhCHadCHb), 4.83 (m, 1H, C5H4), 4.70 (m, 1H,
C5H4), 4.37 (dd, 3J ) 4.8 and 9.9 Hz, PhCHadCHb), 3.87 (m, 1H,
tolyl), 2.13 (s, 3H, CH3 of tolyl), 1.29 (s, 3H, C(CH3)2), 1.16 (s,
3
3H, C(CH3)2), 0.97 (m, 2H, CH2CH3), 0.59 (t, J ) 7.5 Hz, 3H,
CH2CH3). For the other pair of diastereomers: 1H NMR (C6D6) δ
7.97 (br s, 1H, NH), 7.33-6.76 (m, 8H, C6H4), 4.52 (m, 1H, C5H4),
3
4.42 (d, J ) 9.6 Hz, 1H, tolyl CHadCHb), 4.41 (m, 1H, C5H4),
4.09 (dd, 3J ) 3.0 and 9.6 Hz, 1H, tolyl CHadCHb), 4.04 (m, 1H,
3
C5H4), 3.70 (d, J ) 3.0 Hz, 1H, tolyl CHadCHbCHc), 3.28 (m,
1H, C5H4), 2.51 (m, 2H, NHCH2), 2.17 (s, 3H, CH3 of tolyl), 2.15
(s, 3H, CH3 of tolyl), 1.29 (s, 3H, C(CH3)2), 1.08 (s, 3H, C(CH3)2),
0.87 (m, 2H, CH2CH3), 0.47 (t, 3J ) 7.5 Hz, 3H, CH2CH3). Anal.
Calcd for C31H45B10NRu: C, 58.10; H, 7.08; N, 2.19. Found: C,
58.12; H, 7.19; N, 2.45.
3
C5H4), 3.43 (d, J ) 4.8 Hz, 1H, PhCHadCHbCHc), 3.07 (m, 1H,
Preparation of [η5:σ-Me2C(C5H4)(C2B10H10)]Ru[dC(NHPrn)-
CH(Bun)-η2-CHdCH(Bun)] (4a). This complex was prepared as
yellow crystals from [η5:σ-Me2C(C5H4)(C2B10H10)]Ru(NH2Prn)2 (1;
88 mg, 0.20 mmol) and 1-hexyne (46 µL, 0.40 mmol) in toluene
(5 mL) using procedures identical with those reported for 2a: yield
81 mg (71%); mp 153 °C. IR (KBr, cm-1): ν 3448 (m) (NH),
2568 (vs) (BH). 11B{1H} NMR (C6D6): δ -2.9 (1B), -5.0 (1B),
-6.4 (2B), -8.9 (6B). 13C{1H} NMR (C6D6): δ 254.6, 245.4 (Rud
C), 90.1, 88.8, 85.5, 82.6, 80.3, 80.1, 78.1, 75.8, 74.3, 70.9, 56.8,
54.3 (CHa/b and C5H4), 51.2, 50.4 (NHCH2), 47.9, 45.7 (CHc), 41.1,
40.8 (C(CH3)2), 38.5, 37.0, 36.8, 36.5 (CH2CH2CH2CH3), 32.5, 31.9,
31.6, 30.4 (C(CH3)2), 28.9, 28.6, 28.5, 27.2, 22.9, 22.8, 22.7, 22.6,
22.4, 22.1 (Bun and CH2CH3 of NHPrn), 14.5, 14.4, 14.3, 14.2 (CH3
of Bun), 11.4, 11.1 (CH3 of NHPrn); cage carbons were not
observed. For the major pair of diastereomers: 1H NMR (C6D6) δ
7.92 (br s, 1H, NH), 4.45 (m, 1H, C5H4), 4.18 (m, 2H, C5H4), 3.88
(m, 1H, C5H4), 3.33 (dd, 3J ) 2.4 and 9.6 Hz, 1H, nBuCHadCHb),
C5H4), 2.49 (m, 2H, NHCH2), 1.29 (s, 3H, C(CH3)2), 1.17 (s, 3H,
3
C(CH3)2), 0.97 (m, 2H, NHCH2CH2), 0.57 (t, J ) 7.5 Hz, 3H,
CH2CH3). For the other pair of diastereomers: 1H NMR (C6D6) δ
7.99 (br s, 1H, NH), 7.33-6.81 (m, 10H, C6H5), 4.51 (m, 1H, C5H4),
4.45 (d, 3J ) 9.6 Hz, 1H, PhCHadCHb), 4.43 (m, 1H, C5H4), 4.03
(dd, 3J ) 3.3 and 9.6 Hz, PhCHadCHb), 3.97 (m, 1H, C5H4), 3.69
3
(d, J ) 3.3 Hz, 1H, PhCHadCHbCHc), 3.23 (m, 1H, C5H4), 2.45
(m, 2H, NHCH2), 1.29 (s, 3H, C(CH3)2), 1.07 (s, 3H, C(CH3)2),
0.87 (m, 2H, CH2CH3), 0.46 (t, 3J ) 7.5 Hz, 3H, CH2CH3). Anal.
Calcd for C29H41B10NRu: C, 56.84; H, 6.74; N, 2.29. Found: C,
56.91; H, 6.93; N, 2.38.
Preparation of [η5:σ-Me2C(C5H4)(C2B10H10)]Ru[η4-CH(Ph)d
C(NHPrn)CHdCHPh]‚C7H8 (2b‚C7H8). This complex was pre-
pared as yellow crystals from [η5:σ-Me2C(C5H4)(C2B10H10)]Ru(NH2-
Prn)2 (1; 88 mg, 0.20 mmol) and phenylacetylene (44 µL, 0.40
mmol) in toluene (5 mL) using procedures identical with those
reported for 2a. The initial product was a mixture of 2a and 2b in
3
n
3
1
3.11 (dt, J ) 2.7 and 9.6 Hz, 1H, BuCHadCHb), 2.77 (dt, J )
a molar ratio of 32:68, as measured by the H NMR spectrum.
n
2.4 and 8.7 Hz, 1H, BuCHadCHbCHc), 2.58 (m, 2H, NHCH2),
Recrystallization from toluene gave 2b as yellow crystals (37 mg,
30%), mp 167 °C. IR (KBr, cm-1): ν 3451 (m) (NH), 2584 (vs)
(BH). 11B{1H} NMR (CD2Cl2): δ -2.6 (1B), -3.6 (1B), -5.9
(2B), -7.1 (2B), -8.0 (2B), -9.4 (2B). 13C{1H} NMR (CD2Cl2):
δ 143.5, 138.3, 130.1, 128.6, 128.4, 127.8, 126.9, 126.2, 126.1,
125.2 (aryl C), 83.7, 82.6, 81.9, 76.4, 65.7, 59.5, 58.0 (CHd/e/f and
C5H4), 44.2 (NHCH2), 40.1 (C(CH3)2), 31.8, 30.5 (C(CH3)2), 22.1
(CH2CH3), 20.8 (CH3 of toluene), 11.0 (CH2CH3); cage carbons
1.53-0.90 (m, 20H, CH2 and CH3 of nBu, nPr and Me2C), 0.67 (t,
3J ) 7.5 Hz, 3H, CH2CH3 of NHPrn). For the other pair of
diastereomers: 1H NMR (C6D6) δ 7.92 (br s, 1H, NH), 4.65 (m,
2H, C5H4), 3.84 (m, 1H, C5H4), 3.70 (dd, 3J ) 2.4 and 9.9 Hz, 1H,
nBuCHadCHb), 3.69 (m, 1H, C5H4), 3.22 (dt, 3J ) 4.8 and 9.9 Hz,
n
3
n
1H, BuCHadCHb), 2.75 (dt, J ) 2.4 and 8.7 Hz, 1H, BuCHad
CHbCHc), 2.58 (m, 2H, NHCH2), 1.53-0.90 (m, 20H, CH2 and
CH3 of nBu, nPr, and Me2C), 0.73 (t, 3J ) 7.5 Hz, 3H, CH2CH3 of
NHPrn). Anal. Calcd for C25H48B10NRu: C, 52.51; H, 8.46; N, 2.45.
Found: C, 52.25; H, 8.06; N, 2.45.
1
were not observed. H NMR (CD2Cl2): δ 7.39-7.24 (m, 15H,
3
C6H5), 5.54 (d, J ) 8.1 Hz, PhCHddCHe), 5.14 (m, 1H, C5H4),
5.08 (m, 1H, C5H4), 4.39 (m, 1H, C5H4), 3.99 (m, 1H, C5H4), 3.61
(s, 1H, PhCHfdC), 3.22 (m, 1H, NHCH2), 2.83 (m, 1H, NHCH2),
2.34 (s, 3H, CH3 of toluene), 1.73 (d, 3J ) 8.1 Hz, PhCHddCHe),
1.50 (m, 2H, CH2CH3), 1.45 (s, 3H, C(CH3)2), 1.30 (s, 3H,
Preparation of [η5:σ-Me2C(C5H4)(C2B10H10)]Ru[η4-CH-
(ClC6H4)dC(NHPrn)CHdCH(ClC6H4)] (5b). This complex was
prepared as yellow crystals from [η5:σ-Me2C(C5H4)(C2B10H10)]-
Ru(NH2Prn)2 (1; 88 mg, 0.20 mmol) and 1-chloro-4-ethynylbenzene
(55 mg, 0.40 mmol) in toluene (5 mL) using procedures identical
with those reported for 2a: yield 98 mg (73%); mp 176 °C. IR
(KBr, cm-1): ν 3422 (m) (NH), 2562 (vs) (BH). 11B{1H} NMR
(CD2Cl2): δ -2.5 (1B), -3.4 (1B), -5.8 (2B), -7.9 (4B), -9.5
(2B). 13C{1H} NMR (CD2Cl2): δ 143.3, 138.0, 134.9, 132.7, 132.4,
131.6, 129.6, 128.8, 128.1, 125.9, 109.9 (aryl C), 84.9, 83.7, 83.1,
77.5, 65.3, 59.8, 58.1 (CHd/e/f and C5H4), 45.3 (NHCH2), 41.2
(C(CH3)2), 32.9, 31.6 (C(CH3)2), 23.1 (CH2CH3), 12.0 (CH2CH3);
cage carbons were not observed. 1H NMR (CD2Cl2): δ 7.37-7.18
3
C(CH3)2), 0.91 (t, J ) 7.5 Hz, 3H, CH2CH3). Anal. Calcd for
C29H41B10NRu (2b): C, 56.84; H, 6.74; N, 2.29. Found: C, 57.01;
H, 6.73; N, 2.14.
Preparation of [η5:σ-Me2C(C5H4)(C2B10H10)]Ru[dC(NHPrn)-
CH(p-tolyl)-η2-CHdCH(p-tolyl)] (3a). This complex was prepared
as yellow crystals from [η5:σ-Me2C(C5H4)(C2B10H10)]Ru(NH2Prn)2
(1; 88 mg, 0.20 mmol) and 4-ethynyltoluene (51 µL, 0.40 mmol)
in toluene (5 mL) using procedures identical with those reported
for 2a: yield 81 mg (63%); mp 181 °C. IR (KBr, cm-1): ν 3429
(m) (NH), 2582 (vs) (BH). 11B{1H} NMR (C6D6): δ -2.1 (1B),
-3.8 (1B), -5.5 (2B), -7.9 (6B). 13C{1H} NMR (C6D6): δ 251.1,
242.1 (RudC), 141.8, 141.2, 137.8, 137.6, 137.3, 136.7, 136.5,
135.0, 134.5, 134.1, 130.1, 129.1, 127.2, 126.9, 125.5, 125.0 (aryl
C), 88.6, 88.0, 83.5, 82.3, 80.1, 78.2, 77.0, 74.6, 74.3, 72.4, 62.6,
62.4 (CHa/b and C5H4), 52.2, 51.2 (NHCH2), 45.2, 42.3 (CHc), 41.1,
40.8 (C(CH3)2), 32.4, 32.0, 30.2 (C(CH3)2), 23.1, 22.6 (CH2CH3),
21.2, 21.1 (CH3 of tolyl), 11.3, 11.0 (CH2CH3); cage carbons were
not observed. For the major pair of diastereomers: 1H NMR (C6D6)
3
(m, 8H, C6H4), 5.50 (d, J ) 7.8 Hz, PhCHddCHe), 5.12 (m, 1H,
C5H4), 5.06 (m, 1H, C5H4), 4.37 (m, 1H, C5H4), 3.96 (m, 1H, C5H4),
3.52 (s, 1H, PhCHfdC), 3.21 (m, 1H, NHCH2), 2.84 (m, 1H,
3
NHCH2), 1.67 (d, J ) 7.8 Hz, PhCHddCHe), 1.54 (m, 2H, CH2-
3
CH3), 1.46 (s, 3H, C(CH3)2), 1.31 (s, 3H, C(CH3)2), 0.92 (t, J )
7.5 Hz, 3H, CH2CH3). Anal. Calcd for C29H39B10Cl2NRu: C, 51.09;
H, 5.77; N, 2.05. Found: C, 50.83; H, 6.10; N, 1.65.
Preparation of [η5:σ-Me2C(C5H4)(C2B10H10)]Ru[η4-CH-
(BrC6H4)dC(NHPrn)CHdCH(BrC6H4)]‚C7H8 (6b‚C7H8). This
complex was prepared as yellow crystals from [η5:σ-Me2C(C5H4)-
(C2B10H10)]Ru(NH2Prn)2 (1; 88 mg, 0.20 mmol) and 1-bromo-4-
ethynylbenzene (73 mg, 0.40 mmol) in toluene (5 mL) using
procedures identical with those reported for 2a: yield 140 g (81%);
3
δ 7.97 (br s, 1H, NH), 7.33-6.76 (m, 8H, C6H4), 4.95 (d, J )
10.2 Hz, 1H, tolyl CHadCHb), 4.84 (m, 1H, C5H4), 4.70 (m, 1H,
C5H4), 4.44 (dd, 3J ) 4.8 and 10.2 Hz, 1H, tolyl CHadCHb), 3.91
3
(m, 1H, C5H4), 3.43 (d, J ) 4.8 Hz, 1H, tolyl CHadCHbCHc),
3.12 (m, 1H, C5H4), 2.51 (m, 2H, NHCH2), 2.14 (s, 3H, CH3 of

Ruthenium Aminocarbene and Enamine Complexes
Organometallics, Vol. 25, No. 14, 2006 3453
Table 3. Crystal Data and Summary of Data Collection and Refinement for 2a,b, 3a, 5b, and 6b
2a
2b‚C7H8
3a
5b
6b‚C7H8
formula
cryst size (mm)
fw
C29H41B10NRu
0.40 × 0.30 × 0.20
612.8
C36H49B10NRu
0.30 × 0.20 × 0.10
704.9
C31H45B10NRu
0.40 × 0.30 × 0.20
640.9
C29H39B10Cl2NRu
0.50 × 0.40 × 0.30
681.7
C36H47B10Br2NRu
0.50 × 0.40 × 0.40
862.7
cryst syst
space group
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
orthorhombic
P212121
10.591(1)
13.194(1)
22.471(2)
90
90
90
3140.1(2)
4
1.296
monoclinic
P21/c
10.541(2)
20.906(4)
16.959(3)
90
104.12(3)
90
3624.5(13)
4
monoclinic
P21/c
10.743(2)
12.860(3)
24.952(5)
90
99.85(3)
90
3396.5(12)
4
triclinic
P1h
triclinic
P1h
10.486(2)
14.769(3)
14.983(3)
67.50(3)
86.25(3)
75.30(3)
2072.4(7)
2
10.520(2)
12.986(3)
15.644(3)
112.14(3)
95.12(3)
92.37(3)
1965.2(7)
2
Z
D
calcd, Mg/m3
1.292
1.253
1.092
1.458
radiation (λ, Å)
2θ max, deg
µ, mm-1
Mo KR (0.710 73)
Mo KR (0.710 73)
Mo KR (0.710 73)
Mo KR (0.710 73)
Mo KR (0.710 73)
50.0
50.0
50.0
50.0
51.0
0.520
1264
0.460
1464
0.484
1328
0.525
696
2.460
868
F(000)
no. of obsd rflns
no. of params refined
goodness of fit
R1
5515
381
1.062
0.049
5287
392
1.164
0.071
5462
389
1.124
0.057
6349
388
1.160
0.078
6258
452
1.051
0.065
wR2
0.119
0.190
0.159
0.246
0.177
mp 188 °C. IR (KBr, cm-1): ν 3406 (m) (NH), 2542 (vs) (BH).
11B{1H} NMR (CD2Cl2): δ -2.5 (1B), -3.4 (1B), -5.8 (2B), -7.9
(4B), -9.5 (2B). 13C{1H} NMR (CD2Cl2): δ 143.3, 138.0, 134.9,
132.7, 132.4, 131.6, 129.6, 128.8, 128.1, 125.9, 109.9 (aryl C), 84.9,
83.7, 83.1, 77.5, 65.3, 59.8, 58.1 (CHd/e/f and C5H4), 45.3 (NHCH2),
41.2 (C(CH3)2), 32.9, 31.6 (C(CH3)2), 23.1 (CH2CH3), 20.8 (CH3
subsequent Fourier difference techniques and refined anisotropically
for all non-hydrogen atoms by full-matrix least squares calculations
on F2 using the SHELXTL program package.18 For the noncen-
trosymmetrical structure of 2a, the appropriate enantiomorph was
chosen by refining the Flack parameter ø toward zero.19 All
hydrogen atoms were geometrically fixed using the riding model.
Complexes 2b and 6b showed one toluene of solvation. Crystal
data and details of data collection and structure refinements are
given in Table 3.
1
of toluene), 12.0 (CH2CH3); cage carbons were not observed. H
NMR (CD2Cl2): δ 7.52-7.14 (m, 13H, C6H4 + C6H5), 5.50 (d, 3J
) 7.8 Hz, PhCHddCHe), 5.12 (m, 1H, C5H4), 5.06 (m, 1H, C5H4),
4.37 (m, 1H, C5H4), 3.96 (m, 1H, C5H4), 3.52 (s, 1H, PhCHfdC),
3.21 (m, 1H, NHCH2), 2.84 (m, 1H, NHCH2), 2.34 (s, 3H, CH3 of
Acknowledgment. This work was supported by grants from
the Research Grants Council of The Hong Kong Special
Administration Region (Project No. CUHK 4026/02P) and
Mainline Research Scheme of The Chinese University of Hong
Kong (Project No. MR01/002).
3
toluene), 1.67 (d, J ) 7.8 Hz, PhCHddCHe), 1.54 (m, 2H, CH2-
3
CH3), 1.46 (s, 3H, C(CH3)2), 1.31 (s, 3H, C(CH3)2), 0.92 (t, J )
7.5 Hz, 3H, CH2CH3). Anal. Calcd for C36H47B10Br2NRu (6b +
C7H8): C, 50.12; H, 5.49; N, 1.62. Found: C, 49.98; H, 5.69; N,
1.59.
X-ray Structure Determination. All single crystals were
immersed in Paratone-N oil and sealed under N2 in thin-walled
glass capillaries. Data were collected at 293 K on an MSC/Rigaku
RAXIS-II imaging plate using Mo KR radiation from a Rigaku
rotating-anode X-ray generator operating at 50 kV and 90 mA. An
empirical absorption correction was applied using the SADABS
program.17 All structures were solved by direct methods and
Supporting Information Available: CIF files giving X-ray
crystallographic data for 2a, 2b‚C7H8, 3a, 5b, and 6b‚C7H8. This
material is available free of charge via the Internet at http://
pubs.acs.org.
OM060249A
(18) Sheldrick, G. M. SHELXTL 5.10 for Windows NT: Structure
Determination Software Programs; Bruker Analytical X-ray Systems, Inc.:
Madison, WI, 1997.
(17) Sheldrick, G. M. SADABS: Program for Empirical Absorption
Correction of Area Detector Data; University of Go¨ttingen, Go¨ttingen,
Germany, 1996.
(19) Flack, H. D. Acta Crystallogr., Sect. A 1983, 39, 876.