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A straightforward Peterson olefination reaction between either [{(Me2PhSi)3C}Li(THF)] or in situ-generated [(Me3Si)2{Ph2P(BH3)}CLi(THF)n] and paraformaldehyde gives the alkenes (Me2PhSi)2CCH2(1) and (Me3Si){Ph2P(BH3)}CCH2(2), respectively, in good yield. Ultrasonic treatment of 1with lithium in THF yields the lithium complex [{(Me2PhSi)2C(CH2)}Li(THF)n]2(3), which reacts in situwith one equivalent of KOButin diethyl ether to give the potassium salt [{(Me2PhSi)2C(CH2)}K(THF)]2(4). Similarly, ultrasonic treatment of 2with lithium in THF yields the lithium complex [[{Ph2P(BH3)}(Me3Si)C(CH2)]Li(THF)3]2.2THF (5). The bis(phosphine-borane) [(Me3Si){Me2(H3B)P}CH(Me2Si)(CH2)]2(6) may be prepared by the reaction of [Me2P(BH3)CH(SiMe3)]Li with half an equivalent of ClSiMe2CH2CH2SiMe2Cl in refluxing THF. Metalation of 6with two equivalents of MeLi in refluxing THF yields the lithium complex [[{Me2P(BH3)}(Me3Si)C{(SiMe2)(CH2)}]Li(THF)3]2(9), whereas metalation with two equivalents of MeK in cold diethyl ether yields the potassium complex [[{Me2P(BH3)}(Me3Si)C{(SiMe2)(CH2)}]2K2(THF)4]∞(10) after recrystallisation. X-Ray crystallography shows that, whereas the lithium complex 5crystallises as a discrete molecular species, the potassium complexes 4and 10crystallise as sheet and chain polymers, respectively. [ABSTRACT FROM AUTHOR]

Whereas the reactions between either NdI2or TmI2and 1 equiv of the dipotassium salt (Me3Si)2C(SiMe2)2OK2(OEt2) (2) yield only intractable mixtures of products, reactions between LnI2and 1 equiv of (Me3Si)(Me2MeOSi)C(SiMe2CH2)2K2(3) yield the lanthanide(III) compounds (Me3Si)(Me2MeOSi)C(SiMe2CH2)2Ln(OMe)(THF) Ln Tm (9), Nd (10) via a ligand degradation reaction. In contrast, YbI2reacts smoothly with either 2or 3to give the ytterbium(II) alkyls (Me3Si)2C(SiMe2)2OYb(THF)2(4) and (Me3Si)(Me2MeOSi)C(SiMe2CH2)2Yb(THF) (5), respectively, in excellent yields. Compounds 4and 5have been characterized by multielement (1H, 13C1H, 29Si, and 171Yb) NMR spectroscopy, and compounds 4, 5, 9, and 10by elemental analyses and X-ray crystallography. Compounds 9and 10crystallize as structurally similar monomers with a distorted trigonal prismatic geometry about the Ln(III) ions; in 4and 5the Yb centers lie in a distorted trigonal bipyramidal geometry. Compound 5, although potentially diastereomeric, gives rise to a single set of NMR signals over the temperature range 20 to −80 °C, suggesting either the presence of only one diastereomer or that exchange between diastereomers is rapid on the NMR time scale. [ABSTRACT FROM AUTHOR]