Communications
Organometallics, Vol. 22, No. 6, 2003 1173
the 1H NMR spectrum (Scheme 1). Although a complete
separation of the dihydrido species 3 (hexane soluble)
from the oily byproduct PhSiH2CH2SiMe3 was difficult,
3 could be isolated as colorless crystals in 38% yield by
recrystallization from hexane. A crystallographic study
revealed that 3 possesses a tetrameric structure, in
which the four Lu atoms form a tetrahedron (Figure 1).9
There are, in all, eight hydrido ligands in the whole
molecule, one being body-centered in a µ4-H-Lu4 fash-
ion, two being face-capped in a µ3-H-Lu3 form, and five
being edge-bridged in a µ2-H-Lu2 style. Each Lu atom
is thus bonded to one Cp′ and five hydride ligands. The
whole molecule is highly symmetric, which possesses
two crystallographic mirror planes perpendicular to
each other (arbitrarily referred below as plane A and
plane B, respectively, for the convenience of explana-
tion). The Lu1 and Lu1* atoms are in one plane (plane
A), while the Lu2 and Lu2* atoms are in the other
(plane B). The body-centered (H4) and edge-bridged (H3)
hydride ligands are located at the juncture of the two
planes, while the face-capped hydride ligands H1 and
H1* are only in plane B. The four edge-bridged hydrides
(H2, H2*, H2**, and H2***) are out of the mirror planes.
The Cp′ groups on Lu1 and Lu1* are bisected by plane
A, in which the SiMe3 groups (Si2, C15, Si2*, and C15*)
are also located. Similarly, the Cp′ groups on Lu2 and
Lu2* are bisected by plane B, but their SiMe3 groups
are out of this plane and thus result in disorder of the
Cp′ ligands. Although this disorder problem did not
prevent establishing the connectivity of the whole
molecule, further refinement of the structure was dif-
ficult.
by a Lu-O(THF) bond in 4 (cf. Figures 1b and 2b). The
Lu-H bond distances in 4 range from 1.85(3) Å (Lu4-
H4) to 2.49(5) Å (Lu2-H6), which are comparable with
those found in 2 (2.06(5), 2.12(5) Å), [Me2Si(C5Me4)(NtBu)-
Lu(µ-H)(PMe3)]2 (1.93(6), 2.10(6) Å),10b and [Et2Si(C5Me4)-
(C5H5)Lu(µ-H)]2 (2.13(4), 2.16(4) Å)12 and the Yb-H
bonds in [Me2Si(C5Me4)(NCMe2Et)Yb(µ-H)(THF)]2
(2.13(9)-2.57(5) Å).10b The Lu-Cp′ bond distances in 4
(average 2.568(6)-2.591(5) Å) are normal for lutetium-
cyclopentadienyl bonds.
Complexes 3 and 4 are soluble and thermally stable
in common organic solvents such as hexane, toluene,
and THF. Recrystallization of the THF-coordinated
complex 4 in hexane regenerated quantitatively the
unsolvated complex 3. No decomposition or ligand
redistribution was observed in THF-d8 or toluene-d8, as
monitored by 1H NMR. These properties could bode well
for further exploration of the chemistry of this new class
of hydride species.13,14
Ack n ow led gm en t. This work was supported by a
Grant-in-Aid for Scientific Research on Priority Areas
(No. 14078224, “Reaction Control of Dynamic Com-
plexes”) from the Ministry of Education, Culture, Sports,
Science, and Technology of J apan.
Su p p or tin g In for m a tion Ava ila ble: Text giving experi-
mental details, figures giving ORTEP drawings, and tables of
crystallographic data, atomic coordinates, thermal parameters,
and bond distances and angles for 1-4. This material is
OM021014B
To make a molecule of lower symmetry, recrystalli-
zation of 3 from THF was carried out, which successfully
afforded single crystals of 4 suitable for X-ray analysis.
Alternatively, hydrogenolysis of 2 in THF also gave 4
in 85% isolated yields (Scheme 1).11 Complex 4 adopts
a tetrahedral structure similar to that of 3, but one of
its four Lu atoms is coordinated to a THF ligand and
thus loses the symmetry observed in 3 (Figure 2).9 The
overall structure of 4 is almost the same as that of 3,
except that one of the µ3-H-Lu3 bonds in 3 is replaced
(12) Stern, D.; Sabat, M.; Marks, T. J . J . Am. Chem. Soc. 1990, 112,
9558.
(13) Lanthanide metallocene hydride complexes are usually unstable
and easily decompose in THF or toluene. For example, see: Evans,
W. J .; Ulibarri, T. A.; Ziller, J . W. Organometallics 1991, 10, 134 and
references therein.
(14) Structurally characterizable polyhydrido yttrium complexes
could also be isolated in a similar manner.11 Crystallographic data for
[(C5Me4SiMe3)Y(µ-H)2]4(THF): triclinic, space group P1h (No. 2), a )
13.016(3) Å, b ) 13.153(3) Å, c ) 19.699(4) Å, R ) 80.521(3)°, â )
86.775(3)°, γ ) 74.294(3)°, V ) 3202.3(11) Å3, Z ) 2, Dc ) 1.254 g cm-3
,
R (Rw) ) 0.0436 (0.0513). For [(C5Me4SiMe3)Y(µ-H)2]4(THF)2: triclinic,
space group P1h (No. 2), a ) 12.435(2) Å, b ) 13.533(2) Å, c ) 22.017(4)
Å, R ) 98.938(3)°, â ) 92.851(3)°, γ ) 114.406(2)°, V ) 3306.3(10) Å3,
Z ) 2, Dc ) 1.287 g cm-3, R (Rw) ) 0.0486 (0.0596). Preliminary studies
demonstrated that such polyhydrido cluster complexes could show
unprecedented reactivities toward various unsaturated organic sub-
strates. Further studies are in progress and will be reported in due
course.
(11) The reaction of 2 with H2 in THF seemed to be cleaner and
faster than that in toluene. Similar reaction of 1 with H2 in THF also
gave 4, but this reaction was much slower, which took 2 days for com-
pletion. However, the reaction of the yttrium analogue (C5Me4SiMe3)-
Y(CH2SiMe3)2(THF) with H2 occurred rapidly to give [(C5Me4SiMe3)-
Y(µ-H)2]4(THF)n.14