A Dinuclear Holmium(III) `Carbons Apart' Carborane Cluster, [C34H92B8Cl4Ho2Li2N6Si4].C10H8

Abstract

The title compound (

Synthesis and Structural Characterization of closo- and exo-nido-Lanthanacarboranes

“…This disproportionation phenomenon has not been observed before in a C 2 B 9 system, but it is well-known for unsubstituted cyclopentadienyl ligands with an early lanthanide chloride like (C 5 H 5 ) 2 LaCl. 1a, It has also been reported in a C 2 B 10 H 12 2- system . It is interesting to note that the reaction of HoCl 3 with 1 molar equiv of {(TMEDA)Li} 2 {(Me 3 Si) 2 C 2 B 4 H 4 } did not give the expected half-sandwich complex [(Me 3 Si) 2 C 2 B 4 H 4 ]HoCl; instead, a dinuclear sandwich holmacarborane complex was isolated . The above results indicate that the coordination of two identical or similar carborane ligands around a lanthanide ion is favored in all known carborane systems.…”

“…The exo -polyhedral three-center, two-electron Sm−H−B bonds in complex 3 result in the much longer Sm−B distances ranging from 3.025(8) to 3.058(8) Å with an average value of 3.042(8) Å. This type of bonding is also known in other lanthanide boron complexes. ,, The direct Sm(II)−B(dicarbollide) distance is expected to be about 2.926 Å by addition of the difference, 0.191 Å, between Shannon's ionic radii 22 of Sm 2+ (1.270 Å) and Sm 3+ (1.079 Å) to the average Sm−cage atom distance of 2.735 Å in [(C 2 B 9 H 11 ) 2 Sm(THF) 2 ] …”

“…Since then, they have published a series of papers describing the syntheses and structures of the sandwich and half-sandwich complexes of divalent and trivalent lanthanide metals (Sm, Yb, and Eu) with C 2 B 9 H 11 2- and C 2 B 10 H 12 2- ligands. − For example, reactions of Na 2 [C 2 B 9 H 11 ] with LnI 2 (Ln = Sm, Yb) in THF gave half-sandwich complexes of the type Ln(C 2 B 9 H 11 )(THF) 4 , followed by oxidation with [Tl(C 2 B 9 H 11 )] - to generate sandwich complexes of the general formula [Ln(C 2 B 9 H 11 ) 2 ] - . , The reactions of LnI 2 (Ln = Sm, Eu, Yb) with the larger C 2 B 10 H 12 2- were more complicated. Both polymeric and monomeric structures were obtained depending on both the nature of the lanthanide metals and the metal-to-ligand molar ratios employed in the reactions. , The smaller [(Me 3 Si) 2 C 2 B 4 H 4 ] 2- anion was introduced to organolanthanide chemistry by Hosmane and co-workers. − This anion reacted with mid- to late-lanthanide trichlorides to produce various types of lanthanacarboranes depending on both the solvents and the metal-to-carborane molar ratios used in the reactions. For instance, the sandwich species of the general formula [1-Cl-1-(μ-Cl)-2,2‘,3,3‘-(Me 3 Si) 4 -5,6-[(μ-H) 2 Li(TMEDA)]-4,4‘,5‘-[(μ-H) 3 Li(TMEDA)]-1,1‘- commo -Ln(2,3-C 2 B 4 H 4 ) 2 ] - were isolated in good yield from 1:2 (Ln to carborane) molar reaction stoichiometries in a TMEDA ( N,N,N‘,N‘ -tetramethylethylenediamine)/benzene solvent system .…”

Synthesis and Structural Chemistry of Non-Cyclopentadienyl Organolanthanide Complexes

“…As THF seems to be the source of the oxygen atom as well as of the methoxy group, the same reactions were carried out using the TMEDA- with additional Cl, LiCl, or solvent ligands, is bonded to two carborane units which are bridged by one Li(TMEDA). 185,[188][189][190] Repeated crystallization causes the loss of one LiCl(TMEDA) moiety. 185 A very similar structure is presented by the reac- …”

Chemistry ofC-Trimethylsilyl-Substituted Heterocarboranes. 24. Synthetic, Spectroscopic, Structural, and Reactivity Studies on Half- and Full-Sandwich Yttracarboranes of 2,3-C2B4- and 2,4-C2B4-Carborane Ligands

“…Despite the difference in charges on the ligands, it has been established that the coordination chemistry of the dianionic carborane ligands, especially those in the [(CR) 2 B 9 H 9 ] 2- and [(CR) 2 B 4 H 4 ] 2- (R = H or a cage carbon substituent) cage systems, is very similar to that of the monoanionic cyclopentadienyl (Cp) ligands . In particular, there have been a number of recent reports on the half- and full-sandwich metallacarboranes of the lanthanide metals, involving La, Nd, Sm, − Eu, , Gd, ,, Tb, , Dy, , Ho, ,,, Er, , and Yb, , being incorporated into C 2 B 9 - and C 2 B 10 -carborane cages, as well as into both the 2,3-C 2 B 4 (carbons-adjacent) and the 2,4-C 2 B 4 (carbons-apart) cages. On the other hand, although the chemistry of the group 3 organometallic complexes involving Cp ligands has been extensively investigated, the parallel studies in the carborane ligand systems are quite limited.…”