Triorganosiloxy and tetraphenyldisiloxydiolate complexes of the heavier alkaline-earth metals. Crystal structures of [Sr3(tmhd)3(OSiPh3)3] ·0.5C6H5Me (tmhd = 2,2,6,6-tetramethylheptane-3,5-dionate) and [Sr3{O(SiPh2O)2}3 (tetraglyme)2]·0.5C6H5Me [tetraglyme = CH3O(CH2CH2O)4CH3 ]
Abstract
Strontium or barium metal granules reacted with an excess of
HOSiMe
2
Bu
t
in an ammoniacal toluene solution at
-40 °C to produce the corresponding
[M(OSiMe
2
Bu
t
)
2
]
n
.
The strontium complex was also obtained from silanolysis of the
strontium ethoxide
[{Sr(OEt)
2
(HOEt)
4
}
n
]
with an excess of HOSiMe
2
Bu
t
in hot toluene
solution. Similarly, the reaction of
[{Sr(OEt)
2
(HOEt)
4
}
n
]
in hot toluene, with 1 molar equivalent of HOSiPh
3
and Htmhd
(2,2,6,6-tetramethylheptane-3,5-dione) yielded the trimeric complex
[Sr
3
(tmhd)
3
(OSiPh
3
)
3
]
·0.5C
6
H
5
Me. The reaction of strontium or
barium metal granules with 2 molar equivalents of diphenylsilanediol
[Ph
2
Si(OH)
2
] in ammoniacal toluene solution at
-40 °C yielded the polymeric complexes
[{M[O(SiPh
2
O)
2
](H
2
O)(NH
3
)
x
}
n
]
[M = Ca (x = 0.3), Sr
(x = 1) or Ba (x = 0.3)].
Similar reactions for strontium and barium in the presence of an excess
of hmpa [OP(NMe
2
)
3
] produced
[Sr
3
{O(SiPh
2
O)
2
}
3
(hmpa)
5
]·C
6
H
5
Me and
[Ba
3
{O(SiPh
2
O)
2
}
3
(hmpa)
5
(H
2
O)], respectively. Alternatively, when
these reactions were performed in the presence of tetraglyme
[CH
3
O(CH
2
CH
2
O)
4
CH
3
] the water- and NH
3
-free complexes
[M
3
{O(SiPh
2
O)
2
}
3
(tetraglyme)
2
]·0.5C
6
H
5
Me were
obtained (M = Sr or Ba). All complexes have been
characterised by elemental analyses and IR, NMR (
1
H,
13
C and
29
Si, in selected cases
31
P)
spectroscopy and also by TGA/DSC studies. The complexes
[Sr
3
(tmhd)
3
(OSiPh
3
)
3
]
·0.5C
6
H
5
Me and
[Sr
3
{O(SiPh
2
O)
2
}
3
(tetraglyme)
2
]·0.5C
6
H
5
Me have
been characterised by X-ray crystallography. The structure of the former
reveals a trimer of strontium cations stabilised by three tmhd ligands,
and one µ- and two µ
3
-bridging
triphenylsiloxy ligands. Relatively short
Sr · · ·
C (methyl) and
Sr · · ·
C (phenyl) contacts have also been identified in this compound.
In contrast, the three strontium cations in the latter are arranged in
an almost linear array within a
Sr
3
O
9
Si
6
core.
C (methyl) and
Sr · · ·
C (phenyl) contacts have also been identified in this compound.
In contrast, the three strontium cations in the latter are arranged in
an almost linear array within a
Sr
3
O
9
Si
6
core.
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