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The reaction between {(Me3Si)2CH}PH(C6H4-2-OMe) (4) and 1 equiv of BH3·SMe2 yields the phosphine–borane {(Me3Si)2CH}PH(BH3)(C6H4-2-OMe) (5). Subsequent reaction between 5 and 1 equiv of n-BuLi in THF gives the phosphido–borane complex [{(Me3Si)2CH}P(BH3)(C6H4-2-OMe)]Li(THF) (6a), which was isolated as a colorless microcrystalline solid. Treatment of 5 with 1 equiv of PhCH2M yields the corresponding complexes [{(Me3Si)2CH}P(BH3)(C6H4-2-OMe)]ML (ML = Na(THF) (6b), K(pmdeta) (6c); pmdeta = N,N,N′,N″,N″-pentamethyldiethylenetriamine), after crystallization in the presence of the corresponding coligand. While compounds 6b,c are stable toward heat, compound 6a decomposes on heating to 50 °C in toluene to give the cluster [[{(Me3Si)2CH}PH(C6H4-2-O)]Li]6 (7) and the tertiary phosphine–borane {(Me3Si)2CH}P(BH3)(Me)(C6H4-2-OMe) (8). Related C–O cleavage reactions are observed when MgI2 is treated with 2 equiv of 6a and when CaI2 is treated with 2 equiv of [{(Me3Si)2CH}P(BH3)(C6H4-2-OMe)]K in THF, giving [{(Me3Si)2C...

The reaction between (4-tBuC6H4CH2)2Ca and one equivalent of PhP(BH3)(CH2SiMe3)2 (1) in diethyl ether gives the dimeric complex [[PhP(BH3){CH(SiMe3)}2]Ca(OEt2)]2 (2) in good yield. Similar reaction...

N-Heterocyclic carbenes and their heavier homologues are, in part, stabilized by delocalization of the N lone pairs into the vacant p-orbital at carbon (or a heavier Group 14 element center). These interactions are usually absent in the corresponding P-substituted species, owing to the large barrier to planarization of phosphorus. However, judicious selection of the substituents at phosphorus has enabled the synthesis of a diphosphagermylene, [(Dipp)2P]2 Ge, in which one of the P centers is planar (Dipp=2,6-diisopropylphenyl). The planar nature of this P center and the correspondingly short P-Ge distance suggest a significant degree of P-Ge multiple bond character that is due to delocalization of the phosphorus lone pair into the vacant p-orbital at germanium. DFT calculations support this proposition and NBO and AIM analyses are consistent with a Ge-P bond order greater than unity.

Reaction of the alkylzinc bromide Zn(C{SiMe3}2{SiMe2hpp})Br (hppH = 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine) with an excess of sodium hydride gives good yields of an unusual zinc hydride cluster, in which five zinc atoms are linked by (-H) bridges

The lithium reagent (3) reacts with a molar equivalent of anhydrous zinc bromide to give the dimeric compound (2a), in which zinc is four-coordinate. The product from a similar reaction with Li{C(SiMe3)2(SiMe2NPhMe)} is the lithium zincate [Li(THF)2(?-Br)2Zn{C(SiMe3)2(SiMe2NPhMe)}] (4), in which the zinc is only three-coordinate. The crystal structures of 2a and 4 have been determined.

The ‘lower order’ lithium cyanocuprates [Li(thf)2NCCu{C(SiMe3)3}]2 (1d), [Li(thf)2NCCu{C(SiMe3)2(SiMe2NMe2)}]2 (1e) and [Li(thf)NCCu{C(SiMe3)(SiMe2OMe)2}]2 (3) have been obtained from the reactions between copper(I) cyanide and the corresponding organolithium compounds. The compounds 1d and 1e have molecular structures containing four-membered Li2N2 rings but in 3 the lithium is coordinated by the methoxy groups of the ligand and almost linear LiNCCuC sequences are incorporated into fourteen-membered rings. Attempts to make ‘higher order’ cyanocuprates containing tri(organosilyl)methyl groups were unsuccessful and no reactions were observed when the cyanocuprate 1d was treated with alkyl halides or enones.

The organolithium compound Li(THF)(2){C(SiMe3)(2)(SiMe2NMe2)} reacted with one equivalent of MnCl2 to give [Mn(mu-Cl){C(SiMe3)(2)(SiMe2NMe2)}](2) (4) and with 0.5 equivalent of MnCl2 to give Mn{C(SiMe3)(2)(SiMe2NMe2)}(2) together with a small amount of the Mn-III compound [Mn(mu-O){C(SiMe3)(2)(SiMe2NMe2)}](2) (6) formed by adventitious admission of air. With CoBr2, the compound [Co(mu-Br){C(SiMe3)(2)(SiMe2NMe2)}](2) (7) was obtained. The reaction between the lithium compound Li(THF)(2){C(SiMe3)(2)(SiMe2OMe)} and MnCl2 in THF gave [Mn(THF)(mu-Cl){C(SiMe3)(2)(SiMe2OMe)}](2) (5). The crystal structures of compounds 4, 5, 6 and 7 were determined. Compounds 4 and 5 are the first manganese analogues of Grignard reagents containing Mn-C sigma-bonds to be characterised in the solid state. (C) 2002 Elsevier Science B.V. All rights reserved.

The complex [Li(TMEDA) {C(SiMe3)(2)SiMe(2)NMe2}] (1) (TMEDA = N,N,N,N-tetramethylethane-1,2,-diamine) was found to crystallise with an internally coordinated structure like that of [Li(THF)(2){C(SiMe3)(2)SiMe2Me2}] (THF = tetrahydrfuran). In contrast, the compound with Ph in place of NMe2 crystallised as a dialkyllithate [Li(TMEDA)(2)][Li{C(SiME3)(2)(SiMe2Ph)}(2)] (4). The reaction of 4 with MgBr2 gave the doubly bromide-bridged lithium-magnesium complex [Li(TMEDA)(mu -Br)(2)Mg{C(SiMe3)(2)(SiMe2Ph)} (THF)] (6), and that of [Li(THF){C(SiMe3)(2)(SiMe2C5H4N-2)}] gave the singly bridged compound [Li(THF)(3)(mu -Br)MgBr{C(SiMe3)(2)(SiMe2C5H4N-2)] (8). The Grignard reagents [Mg{C(SiMe3)(3)}I(OEt2)](2) (10) and [Mg{C(SiMe3)(2) (SiMe2Ph)} I(OEt2)](2) (11) were obtained from the reactions between (Me3Si)(3)CI and (Me2Ph)(Me3Si)CI, respectively, with magnesium metal and shown to have halide-bridged structures. The unsymmetrical dialkylmagnesium [MgBu{C(SiMe3)(2)(SiMe2NMe2)}(THF)] (13), was prepared from a mixture of LiBu, 1 and [MgBr2(OEt2)(2)]. (C) 2001 Elsevier Science B.V. All rights reserved.

The alkylaluminate [Li(THF) 2 AlH 3 C(SiMe 3 ) 2 (SiMe 2 NMe 2 )] 2 ( 3 ), obtained by the reaction between [LiC(SiMe 3 ) 2 (SiMe 2 NMe 2 )·2THF] and LiAlH 4 , has a cyclic structure like those of the compounds [Li(THF) 2 AlH 3 R] 2 (R=C(SiMe 3 ) 3 ( 1 ), or C(SiMe 2 Ph) 3 ( 2 )). The Al and Li atoms are linked by hydride bridges and the NMe 2 groups are not coordinated to metal centres. The compound 1 reacts (i) with one equivalent of SiMe 3 Cl to give the cyclic dialuminate ( 4 ) (characterised by an X-ray study); (ii) with two equivalents of SiMe 3 Cl to give the alaneTHF complex (Me 3 Si) 3 CAlH 2 ·THF ( 5 ); and (iii) with an excess of pyrazole to give [LiAlH(C 3 H 3 N 2 ) 2 C(SiMe 3 ) 3 ] 2 ( 7 ), in which Al and Li atoms are linked by both hydride and pyrazolato bridges. The compound (Me 2 PhSi) 3 CAlH 2 ·THF ( 6 ) has been obtained by the reaction of 2 with two equivalents of SiMe 3 Cl.

The compounds HC(SiMe3)(SiMe2X)2, X = NMe2 or OMe, have been synthesized in several steps from the phenyl derivative HC(SiMe3)(SiMe2Ph)2 and metallated to give organometallic compounds of the type MC(SiMe3)(SiMe2X)2, M = K or Li. The structures of the compounds KC(SiMe3)2(SiMe2NMe2) and KC(SiMe2NMe2)3 consist of infinite chains in which cations are co-ordinated to both nitrogen and carbon centres, whereas the lithium compound [LiC(SiMe3)(SiMe2OMe)2]2 crystallises in a lattice of dimeric cage molecules. Structural trends in the series MC(SiMe3)n(SiMe2X)3-n, n = 0–3, M = K or Li, X = NMe2 or OMe, are discussed.

The organolithium reagent (1) is readily obtained by reaction of the chloride (Me3Si)2(Me2NMe2Si)CCl with LiBu in THF (tetrahydrofuran) at low temperature. Reactions of 1 with HgBr2, AlCl3, GaCl3, and SnCl4 give [Hg{C(SiMe3)2(SiMe2NMe2)}2] (2), (3), Ga{C(SiMe3)2(SiMe2NMe2)}Cl2 (5), and [Sn{C(SiMe3)2(SiMe2NMe2)}Cl3] (6), respectively, and treatment of 3 with LiPh gives (4). Crystal structure determinations have shown that there is intramolecular coordination of the N atom to the metal M, with formation of a planar four-membered ring, in 1, 3, 4, and 5 (but not 2). Engagement of the lone pair on N in coordination with Al in 3 results in an exceptionally long Si−N bond length of 1.875(2) A, some 0.16 A longer than that in 2 and in simple silylamines generally; the Si−N bond is possibly shorter in 4 (1.851(2) A) and 5 (1.858(4) A), and is markedly so in 1 (1.796(4) A), but still notably long. The lengths of the N−metal bonds in these compounds are similar to those between alkylamines and the metals in coordin...

The structure of a triclinic form of the organolithium derivative LiR, R = C(SiMe3)2(SiMe2{hpp}) (1) (hppH = 1,3,4,6,7,8,-hexahydro-2H-pyrimido[1,2-a]pyrimidine) comprises dimers [1]2 held together by Li···H3C interactions like those in the polymeric structure [1]∞ of the previously described orthorhombic form. Compound 1 reacts with the chlorides MCl2 (M = Hg or Sn) to give compounds HgRCl (2) or SnRCl (3), which have been characterised by NMR spectroscopy and X-ray crystallography. The structural parameters and conformations of the metallacycles MRLn are compared with those in related compounds containing bulky organosilicon ligands with pendant nitrogen donors. Compound 3 reacts with Li[P{H}Ar*] (Ar* = 2,4,6-tBu3C6H2) to give the crowded phosphanide SnR(P{H}Ar*) (4).

The disiloxane O{SiMe2CH(SiMe3)2}2 is readily metallated by LiMe in thf (thf = tetrahydrofuran) to give the compound SiMe2C(SiMe)3LiC(SiMe3)2SiMe2OLi(thf)2, the crystal structure of which is reported.