208
A. V. Pomogaeva and A. Y. Timoshkin
This reaction is activated by metallic sodium, NaAlH 4 , or [HAlNR] 6 . Since such
reaction requires excess of molecular hydrogen, it was assumed that the first step is
in situ generation of AlH 3 . Reaction of LiAlH 4 with NH 3 RCl has also been used to
generate iminoalanes [89]:
LiAlH 4 + NH 3 RCl=
1 / n [HAlNR] n + 3 H 2 + LiCl
Direct reduction of nitriles RCN by AlH 3 ·NMe 3 also results in the formation of
iminoalanes [89]:
AlH 3 · NMe 3 + RCN+
1 / n [HAlNCH 2 R] n + NMe 3
Similar approach was used by Roesky for the synthesis of various hexamer
compounds [80], which were used as a starting materials for the functionalization
by substitution reactions [80, 81, 84].
It should be also noted that reaction between MR 3 and YH 3 is one of the major
methods in production of 13–15 binary materials in CVD processes [90–92], which
occurs at high temperatures. In the condensed phase chemistry, it has been mostly
used for the production of iminoalanes.
6.2.2 Structural Features and Reactivity of Needle-Shaped
Oligomers
6.2.2.1 Tetramers
Formally, several isomers are possible for the [RMYR ] 4 composition, but the
cubane-type structures in which both metal and pnictogen centers adopt coordination number 4 (Fig. 6.2a) are the most stable [50]. The metal-metal bonded isomer
with Al 4 tetrahedral core Al 4 (NRR ) 4 (Fig. 6.2b) is also structurally characterized
[93]. Structural properties of the experimentally known more than forty 13–15
cubanes have been discussed in [20]. Uhl [11] reviewed the hydrazine-based
compounds, which possess M 4 N 8 core with five-membered rings, which formally
corresponds to the [RMYR ] 4 composition.
Coordination number 4 both on metal and pnictogen centers makes cubanes
relatively stable species. Thus, [ i PrInPSiPh 3 ] 4 is relatively stable toward alcoholysis
but unstable with respect to photolysis and electrochemical oxidation [95]. Many of
cubane clusters are volatile compounds and can be purified by vacuum sublimation.
Structures of cubane-type clusters are usually highly symmetric with equal M-Y
bond distances in the M 4 Y 4 cube.
Despite coordination number 4 on metal center, metal atoms in cubanes are
able to participate in donor-acceptor interactions. Thus, each In atom in [MeIn
(THF)N(4-C 6 H 4 F)] 4 is coordinated to THF molecule [96], which may result
from the larger atomic radius of indium. [HAlN i Pr] 4 forms solid adduct with
A. V. Pomogaeva and A. Y. Timoshkin
This reaction is activated by metallic sodium, NaAlH 4 , or [HAlNR] 6 . Since such
reaction requires excess of molecular hydrogen, it was assumed that the first step is
in situ generation of AlH 3 . Reaction of LiAlH 4 with NH 3 RCl has also been used to
generate iminoalanes [89]:
LiAlH 4 + NH 3 RCl=
1 / n [HAlNR] n + 3 H 2 + LiCl
Direct reduction of nitriles RCN by AlH 3 ·NMe 3 also results in the formation of
iminoalanes [89]:
AlH 3 · NMe 3 + RCN+
1 / n [HAlNCH 2 R] n + NMe 3
Similar approach was used by Roesky for the synthesis of various hexamer
compounds [80], which were used as a starting materials for the functionalization
by substitution reactions [80, 81, 84].
It should be also noted that reaction between MR 3 and YH 3 is one of the major
methods in production of 13–15 binary materials in CVD processes [90–92], which
occurs at high temperatures. In the condensed phase chemistry, it has been mostly
used for the production of iminoalanes.
6.2.2 Structural Features and Reactivity of Needle-Shaped
Oligomers
6.2.2.1 Tetramers
Formally, several isomers are possible for the [RMYR ] 4 composition, but the
cubane-type structures in which both metal and pnictogen centers adopt coordination number 4 (Fig. 6.2a) are the most stable [50]. The metal-metal bonded isomer
with Al 4 tetrahedral core Al 4 (NRR ) 4 (Fig. 6.2b) is also structurally characterized
[93]. Structural properties of the experimentally known more than forty 13–15
cubanes have been discussed in [20]. Uhl [11] reviewed the hydrazine-based
compounds, which possess M 4 N 8 core with five-membered rings, which formally
corresponds to the [RMYR ] 4 composition.
Coordination number 4 both on metal and pnictogen centers makes cubanes
relatively stable species. Thus, [ i PrInPSiPh 3 ] 4 is relatively stable toward alcoholysis
but unstable with respect to photolysis and electrochemical oxidation [95]. Many of
cubane clusters are volatile compounds and can be purified by vacuum sublimation.
Structures of cubane-type clusters are usually highly symmetric with equal M-Y
bond distances in the M 4 Y 4 cube.
Despite coordination number 4 on metal center, metal atoms in cubanes are
able to participate in donor-acceptor interactions. Thus, each In atom in [MeIn
(THF)N(4-C 6 H 4 F)] 4 is coordinated to THF molecule [96], which may result
from the larger atomic radius of indium. [HAlN i Pr] 4 forms solid adduct with