“…In both 29 and 30 the presence of the bridged hydrogen on the carborane led to the metal occupying bridging positions rather than apical ones. This has generally been found to be the case for main group, transition metal, and lanthanide 3b carborane complexes. The exceptions are the group 1 half-sandwich carborane complexes, such as 1 and 2 , and the full-sandwich lithiacarborane [Li + (TMEDA) 2 ][ commo- 1,1‘-Li{2,3-(SiMe 3 ) 2 -2,3-C 2 B 4 H 5 } 2 ], where X-ray structures show the metals occupy apical positions above the C 2 B 3 faces. ,, It should be noted that, on standing, the half-sandwich group 1 carboranes reverted to their respective exo -metallacarboranes. , 4 Synthesis of Erbacarborane {(η 5 -C 5 H 5 ) 2 -1-Er[4,5-(μ 2 -H)-2,3-(SiMe 3 ) 2 -2,3-C 2 B 4 H 4 ]}·(THF) (29) 5 Synthesis of Gadolinacarborane {(η 8 -C 8 H 8 )-1-Gd[4,5-(μ-H)-2,3-(SiMe 3 ) 2 -2,3-C 2 B 4 H 4 ]}·2(THF) (30) …”
The reactivities of the monosodium-complexed carborane precursors nido-1-Na(C4H8O)-2-(R)-3-(SiMe3)-2,3-C2B4H5 (R = SiMe3 (1) or Me (2)) with a number of lanthanide halides were investigated. The
reaction of LnCl3 (or LnBr3) with 1 in a 1:2 molar ratio in dry THF at 60 °C produced the dimerized
half-sandwich lanthanacarborane complexes [2,3-(SiMe3)2-1-X-1-(THF)
m
-1-Ln(η5-2,3-C2B4H4)]2·n(THF)
(3, Ln = Y, X = Cl, m = 2, n = 1; 4, Ln = La, X = Br; m = 1, n = 0; 5, Ln = Ce, X = Br; m = 1,
n = 0; 6, Ln = Pr, X = Br; m = 2, n = 1; 7, Ln = Nd; X = Cl, m = 2, n = 1; 8, Ln = Sm; X = Br,
m = 2, n = 0; 9, Ln = Gd; X = Cl, m = 2, n = 1; 10, Ln = Tb, X = Cl, m = 2, n = 1; 11, Ln = Dy,
X = Cl, m = 2, n = 1; 12, Ln = Ho, X = Cl, m = 2, n = 1; 13, Ln = Er, X = Cl, m = 2, n = 1; 14,
Ln = Tm, X = Cl, m = 2, n = 1; 15, Ln = Yb, X = Cl, m = 2, n = 1; 16, Ln = Lu X = Cl, m = 2,
n = 1) as crystalline solids in 70−92% isolated yields. In a similar manner, the reactions of 2 with LnCl3
at 65 °C gave the corresponding complexes [2-Me-3-(SiMe3)-1-Cl-1-(THF)2-1-Ln(η5-2,3-C2B4H4)]2 (17,
Ln = Nd; 18, Ln = Dy; 19, Ln = Ho; 20, Ln = Er; 21, Ln = Yb) as crystalline solids in 72−80% yield.
In both series of the reactions, 1 equiv of the particular neutral carborane was also produced. The
substitution of the chloride ions in complexes 17 and 20 by 2 gave the half-sandwich lanthanacarborane
clusters {2-Me-3-(SiMe3)-1-[4,5-(μ-H)-nido-2-Me-3-(SiMe3)-2,3-C2B4H5]-1-Ln(η5-2,3-C2B4H4)}2·n(THF)
(22, Ln = Nd, n = 2; 24, Ln = Er, n = 1) as crystalline solids in 82−87% yield. The reaction of 19 and
2 produced the trimer {2-Me-3-(SiMe3)-1-[4,5-(μ-H)-nido-2-Me-3-(SiMe3)-2,3-C2B4H5]-1-Ho(η5-2,3-C2B4H4)}3·8(THF) (23) in 57% yield. Complexes 22, 23, and 24 could directly be obtained in good yield
(56−67%) from the reaction of 2 with the corresponding LnCl3 at 65 °C in molar ratios of 3:1 in dry
THF. Similarly, the mixed coordinated complex {2,3-(SiMe3)2-1-[4,5-(μ-H)-(nido-2-Me-3-(SiMe3)-2,3-C2B4H5)]-1-Gd(η5-2,3-C2B4H4)}2·3(THF) (25) was obtained by reacting compound 9 with 2. To investigate
the importance of the halide in these reactions, (η5-Cp)LnCl2 (Ln = Tb, Dy, Er) with 1 in a 1:2 molar
ratio produced lanthanacarborane complexes [1-(η5-C5H5)-2,3-(SiMe3)2-1-Ln(η5-2,3-C2B4H4)]2·n(THF)
(26, Ln = Tb, n = 2; 27, Ln = Dy, n = 2; 28, Ln = Er, n = 3) as crystalline solids in 77−82% isolated
yields. On the other hand, the reactions of (η5-Cp)2ErCl and (η8-C8H8)GdCl with 1 in 1:1 molar ratios
did not produce the half-sandwich lanthanacarboranes, but rather gave the exo-polyhedral products {exo-(η5-C5H5)2Er[4,5-(μ-H)-2,3-(SiMe3)2-2,3-C2B4H4]}·(THF) (29) and {exo-(η8-C8H8)Gd[4,5-(μ-H)-2,3-(SiMe3)2-2,3-C2B4H4]·2(THF) (30) as crystalline solids in 76% and 73% isolated yield, respectively. All
compounds were characterized by IR spectroscopy and elemental analysis, whereas compounds 3, 7−9,
10−16, 18−22, 29, and 30 were characterized by single-crystal X-ray diffraction studies. The diamagnetic
compounds 3, 4, and 16 were additionally characterized by 1H, 13C, and 11B NMR s...
“…In both 29 and 30 the presence of the bridged hydrogen on the carborane led to the metal occupying bridging positions rather than apical ones. This has generally been found to be the case for main group, transition metal, and lanthanide 3b carborane complexes. The exceptions are the group 1 half-sandwich carborane complexes, such as 1 and 2 , and the full-sandwich lithiacarborane [Li + (TMEDA) 2 ][ commo- 1,1‘-Li{2,3-(SiMe 3 ) 2 -2,3-C 2 B 4 H 5 } 2 ], where X-ray structures show the metals occupy apical positions above the C 2 B 3 faces. ,, It should be noted that, on standing, the half-sandwich group 1 carboranes reverted to their respective exo -metallacarboranes. , 4 Synthesis of Erbacarborane {(η 5 -C 5 H 5 ) 2 -1-Er[4,5-(μ 2 -H)-2,3-(SiMe 3 ) 2 -2,3-C 2 B 4 H 4 ]}·(THF) (29) 5 Synthesis of Gadolinacarborane {(η 8 -C 8 H 8 )-1-Gd[4,5-(μ-H)-2,3-(SiMe 3 ) 2 -2,3-C 2 B 4 H 4 ]}·2(THF) (30) …”
The reactivities of the monosodium-complexed carborane precursors nido-1-Na(C4H8O)-2-(R)-3-(SiMe3)-2,3-C2B4H5 (R = SiMe3 (1) or Me (2)) with a number of lanthanide halides were investigated. The
reaction of LnCl3 (or LnBr3) with 1 in a 1:2 molar ratio in dry THF at 60 °C produced the dimerized
half-sandwich lanthanacarborane complexes [2,3-(SiMe3)2-1-X-1-(THF)
m
-1-Ln(η5-2,3-C2B4H4)]2·n(THF)
(3, Ln = Y, X = Cl, m = 2, n = 1; 4, Ln = La, X = Br; m = 1, n = 0; 5, Ln = Ce, X = Br; m = 1,
n = 0; 6, Ln = Pr, X = Br; m = 2, n = 1; 7, Ln = Nd; X = Cl, m = 2, n = 1; 8, Ln = Sm; X = Br,
m = 2, n = 0; 9, Ln = Gd; X = Cl, m = 2, n = 1; 10, Ln = Tb, X = Cl, m = 2, n = 1; 11, Ln = Dy,
X = Cl, m = 2, n = 1; 12, Ln = Ho, X = Cl, m = 2, n = 1; 13, Ln = Er, X = Cl, m = 2, n = 1; 14,
Ln = Tm, X = Cl, m = 2, n = 1; 15, Ln = Yb, X = Cl, m = 2, n = 1; 16, Ln = Lu X = Cl, m = 2,
n = 1) as crystalline solids in 70−92% isolated yields. In a similar manner, the reactions of 2 with LnCl3
at 65 °C gave the corresponding complexes [2-Me-3-(SiMe3)-1-Cl-1-(THF)2-1-Ln(η5-2,3-C2B4H4)]2 (17,
Ln = Nd; 18, Ln = Dy; 19, Ln = Ho; 20, Ln = Er; 21, Ln = Yb) as crystalline solids in 72−80% yield.
In both series of the reactions, 1 equiv of the particular neutral carborane was also produced. The
substitution of the chloride ions in complexes 17 and 20 by 2 gave the half-sandwich lanthanacarborane
clusters {2-Me-3-(SiMe3)-1-[4,5-(μ-H)-nido-2-Me-3-(SiMe3)-2,3-C2B4H5]-1-Ln(η5-2,3-C2B4H4)}2·n(THF)
(22, Ln = Nd, n = 2; 24, Ln = Er, n = 1) as crystalline solids in 82−87% yield. The reaction of 19 and
2 produced the trimer {2-Me-3-(SiMe3)-1-[4,5-(μ-H)-nido-2-Me-3-(SiMe3)-2,3-C2B4H5]-1-Ho(η5-2,3-C2B4H4)}3·8(THF) (23) in 57% yield. Complexes 22, 23, and 24 could directly be obtained in good yield
(56−67%) from the reaction of 2 with the corresponding LnCl3 at 65 °C in molar ratios of 3:1 in dry
THF. Similarly, the mixed coordinated complex {2,3-(SiMe3)2-1-[4,5-(μ-H)-(nido-2-Me-3-(SiMe3)-2,3-C2B4H5)]-1-Gd(η5-2,3-C2B4H4)}2·3(THF) (25) was obtained by reacting compound 9 with 2. To investigate
the importance of the halide in these reactions, (η5-Cp)LnCl2 (Ln = Tb, Dy, Er) with 1 in a 1:2 molar
ratio produced lanthanacarborane complexes [1-(η5-C5H5)-2,3-(SiMe3)2-1-Ln(η5-2,3-C2B4H4)]2·n(THF)
(26, Ln = Tb, n = 2; 27, Ln = Dy, n = 2; 28, Ln = Er, n = 3) as crystalline solids in 77−82% isolated
yields. On the other hand, the reactions of (η5-Cp)2ErCl and (η8-C8H8)GdCl with 1 in 1:1 molar ratios
did not produce the half-sandwich lanthanacarboranes, but rather gave the exo-polyhedral products {exo-(η5-C5H5)2Er[4,5-(μ-H)-2,3-(SiMe3)2-2,3-C2B4H4]}·(THF) (29) and {exo-(η8-C8H8)Gd[4,5-(μ-H)-2,3-(SiMe3)2-2,3-C2B4H4]·2(THF) (30) as crystalline solids in 76% and 73% isolated yield, respectively. All
compounds were characterized by IR spectroscopy and elemental analysis, whereas compounds 3, 7−9,
10−16, 18−22, 29, and 30 were characterized by single-crystal X-ray diffraction studies. The diamagnetic
compounds 3, 4, and 16 were additionally characterized by 1H, 13C, and 11B NMR s...
“…Since (η 5 -C 5 R 5 )Co(CH 3 ) 2 C 2 B 3 H 5 is a direct analogue of (CH 3 ) 2 C 2 B 4 H 6 in which a (η 5 -C 5 R 5 )Co moiety replaces the apical B−H vertex, their behavior should parallel the unsubstituted mercuracarboranes. In addition to μ,μ‘-[(CH 3 ) 2 C 2 B 4 H 5 ] 2 Hg, a bridged trimethylsilyl-substituted mercuracarborane, μ,μ‘-[2-(Si(CH 3 ) 3 )-3-(CH 3 )-2,3-C 2 B 4 H 5 ] 2 Hg, has also been reported (see Figure ). The most surprising aspect of the structure is in the arrangement of the ligands around the Hg.…”
Section: Metallacarboranes Of D-block Elementsmentioning
A review of the chemistry of polyhedral cluster complexes in which s-, p-, d- and f-block
metals are incorporated mainly into C
cage
-trimethylsilyl-substituted C2B4 carborane cages
is presented. While the main thrust of this review is on the results obtained in authors'
laboratories, comparisons are made to similar systems and to those involving both large-
and small-cage carboranes. In this way we hope to demonstrate the unique chemistry of the
small-C2B4-cage systems that has emerged over the last 40 years. However, a full picture of
the chemistry of these systems cannot be presented without heavy reference to the larger,
more stable 11- and 12-vertex cages, which in many ways preceded their more diminutive
cousins. The focus of much of the current research is directed toward systematizing the
chemistry of metallacarboranes with the aim of promoting their use as possible electronic,
ceramic, and/or catalytic materials. However, such endeavors are based on our knowledge
about the fundamental interactions that are at work in determining the structures and
properties of these cluster complexes. This review attempts to provide such an overview of
small-cage heterocarborane chemistry.
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