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Addition of N,N'-dialkylcarbodiimides to lithio-ortho-carborane was carried out to readily access carboranylamidinate anions. The method represents a novel difunctional boron-rich ligand system for main group and transition elements (Li, Sn, Cr) and revealed an unexpected N,C-coordination mode instead of N,N'-chelation.

Readily accessible and easy-to-use phenyliodine(III) dichloride (PhI[Cl.sub.2]) is described as an innovative and superior reagent for the one-electron oxidation of cerium(III) complexes, comprising of amide, amidinate and cyclopentadienyl derivatives. It is used for the synthesis and structural characterization of the first members of three new classes of chloro-functionalized (organo)cerium(IV) compounds, including the [Cp.sub.3]CeCl.

A series of new homo- and heterometallic lithium and lithium/ lanthanide disiloxanediolate complexes were prepared and fully characterized. Three new adducts of dilithium tetraphenyldisiloxanediolate, [(Ph2SiOLi)2O] (2), with simple Lewis bases (Et2O, THF, DME) were prepared by treatment of Ph2Si(OH)OSiPh2(OH) (1) with 2 equiv. of n-butyllithium in the respective donor solvent. This way the adducts [{Ph2SiOLi(Et2O)}2O]2 (3), [{Ph2SiOLi(THF)}2O]2 (4), and [{Ph4Si2O(OLi)2}2(DME)3] (5a) were obtained in a straightforward manner and in nearly quantitative yields. Treatment of anhydrous lanthanide(III) chlorides LnCl3 (Ln = Tb, Lu) with 2 equiv. of 2 in THF afforded the new lanthanide(III) bis(disiloxanediolate) complexes [{(Ph2SiO)2O}2{Li(THF)2}2]TbCl (6) and [{(Ph2SiO)2O}2{Li(THF)2}2]LuCl (7) in high yields. Similar reactions of LnCl3 (Ln = Ce, Nd) with 3 equiv. of 2 provided the heterometallic Li/Ln tris(disiloxanediolate) complexes [{(Ph2SiO)2O}3{Li(DME)}2{Li(THF)}]Ce (8) and [{(Ph2SiO)2O}3{Li(DME)}{Li(Et2O)}{Li(THF)}]Nd (9). All title compounds were structurally characterized through single-crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]

The lithium-cyclopropylethynylamidinates Li[c-C3H5–C≡C–C(NR)2] (1a: R = iPr, 1b: R = cyclohexyl (Cy)) have been used as precursors for the preparation of five new series of half-sandwich complexes. These complexes contain the large flat cyclooctatetraenyl ligand (C8H82−, commonly abbreviated as COT), and were isolated as solvated, unsolvated and inverse sandwich complexes. Treatment of the halide precursors [(COT)Pr(μ-Cl)(THF)2]2 with 1b and [(COT)Nd(μ-Cl)(THF)2]2 with 1a and 1b in THF in a 1 : 2 molar ratio, respectively, afforded (COT)Ln[μ-c-C3H5–C≡C–C(NR)2]2Li(L) (2: Ln = Pr, R = Cy, L = Et2O; 3: Ln = Nd, R = iPr, L = THF; 4: Ln = Nd, R = Cy, L = THF). Treatment of the dimeric cerium(iii) bis(cyclopropylethynylamidinate) complexes [{c-C3H5–C≡C–C(NR)2}2Ce(μ-Cl)(THF)]2 (5: R = iPr; 6: R = Cy) in situ with K2C8H8 in a 1 : 1 molar ratio in THF at room temperature afforded the inverse-sandwich complexes (μ–η8:η8-COT)[Ce{c-C3H5–C≡C–C(NR)2}2]2 (7: R = iPr; 8: R = Cy). This reaction represents a new method for encapsulation of a planar (C8H8)2− ring in lanthanide complexes containing amidinate ligands in the outer decks. Novel unsolvated dinuclear lanthanide half-sandwich complexes were prepared by using the precursors 1a, 1b and COT2−. Unlike the complexes 2–4, the reaction of [(COT)Pr(μ-Cl)(THF)2]2 with 1a afforded the unsolvated centrosymmetric complex [(COT)Pr(μ-c-C3H5–C≡C–C(NiPr)2)]2 (9). These dimeric structures could be also accessed by reaction of LnCl3 (Ln = Ce or Nd) with 1a or 1b and K2COT in a 1 : 1 : 1 molar ratio as a one-pot reaction to give novel [(COT)Ln(μ-c-C3H5–C≡C–C(NR)2)]2 complexes (10: Ln = Ce, R = iPr; 11: Ln = Ce, R = Cy; 12: Ln = Nd, R = iPr). Similar treatment of HoCl3 with 1a or 1b and K2COT as three-component reactions in a 1 : 1 : 1 molar ratio afforded the solvated half-sandwich complexes (COT)Ho(c-C3H5–C≡C–C(NR)2)(THF) (13: R = iPr; 14: R = Cy). A unique multidecker sandwich complex [(μ–η8:η8-COT){Nd(c-C3H5–C≡C–C(NCy)2)(μ-Cl)}2]4 (15) was prepared by reaction of anhydrous NdCl3 with K2COT and 1b in a one-pot reaction. The solid state structure of 15 revealed the presence of an unprecedented macrocyclic sandwich compound (“giant neodymium wheel”) consisting of four COT rings sandwiched between eight Nd3+ ions, and each Nd3+ ion is bonded to one amidinate ligand and bridged by two chlorine atoms with the neighbouring Nd3+ ion. [ABSTRACT FROM AUTHOR]

The new zirconium bent metallocenes (COT)Zr(CptBu2)Cl (1) and (COT)Zr(Cp'')Cl (2) were synthesized in a straightforward manner and in high yields (1: 91%, 2: 86%) by treatment of in situprepared (COT)ZrCl2(THF) with 1 equiv. of K(CptBu2) or K(Cp''), respectively (COT = η;8-cyclooctatetraenyl; CptBu2 = η5-1,3-di-tert- butylcyclopentadienyl; Cp'' = η5-1,3-bis(trimethylsilyl)cyclopentadienyl). Subsequent reaction of 1 with 1 equiv. of phenyllithium afforded the σ-phenyl derivative (CptBu2)Zr(COT)Ph (3) as orange crystals in 83% isolated yield. All three new compounds were structurally characterized through single-crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]