Effect of peripheral donor substituents on the binding modes of phosphinomethanide ligands. Synthesis and crystal structures of alkali metal derivatives of an O-functionalised phosphinomethanide ligand

The O-functionalised tertiary phosphine {(Me3Si)2CH}P(C6H4-2-CH2OMe)2 (9) is accessible via the reaction of {(Me3Si)2CH}PCl2 with two equivalents of in situ generated 2-LiC6H4CH2OMe. Phosphine 9 is readily deprotonated by Bu(n)Li to give the lithium phosphinomethanide [[{(Me3Si)2C}P(C6H4-2-CH2OMe)2]Li] (13), which undergoes metathesis reactions with the alkoxides MOR [M = Na, K, R = Bu(t); M = Rb, R = 2-ethylhexyl] to give the heavier alkali metal phosphinomethanides [[{(Me3Si)2C}P(C6H4-2-CH2OMe)2]M]n in good yields [M = Na (14), n= 2; M = K (15), Rb (16), n=[infinity]]. Compounds 9, [{(Me3Si)2CH}P(C6H4-2-CH2OMe)2LiBr]2 (10), and 14-16 have been studied by X-ray crystallography; in the solid state 14 adopts a dimeric structure, whereas 15 and 16 crystallise as one-dimensional polymers.     

Synthesis and structures of some new types of lithium beta-diketiminates

The tetracyclic dilithio-Si,Si'-oxo-bridged bis(N,N'-methylsilyl-beta-diketiminates) 2 and 3, having an outer LiNCCCNLiNCCCN macrocycle, were prepared from [Li{CH(SiMe(3))SiMe(OMe)(2)}](infinity) and 2 PhCN. They differ in that the substituent at the beta-C atom of each diketiminato ligand is either SiMe(3) (2) or H (3). Each of and has (i) a central Si-O-Si unit, (ii) an Si(Me) fragment N,N'-intramolecularly bridging each beta-diketiminate, and (iii) an Li(thf)(2) moiety N,N'-intermolecularly bridging the two beta-diketiminates (thf = tetrahydrofuran). Treatment of [Li{CH(SiMe(3))(SiMe(2)OMe)}](8) with 2Me(2)C(CN)(2) yielded the amorphous [Li{Si(Me)(2)((NCR)(2)CH)}](n) [R = C(Me)(2)CN] (4). From [Li{N(SiMe(3))C(Bu(t))C(H)SiMe(3)}](2) (A) and 1,3- or 1,4-C(6)H(4)(CN)(2), with no apparent synergy between the two CN groups, the product was the appropriate (mu-C(6)H(4))-bis(lithium beta-diketiminate) 6 or 7. Reaction of [Li{N(SiMe(3))C(Ph)=C(H)SiMe(3)}(tmeda)] and 1,3-C(6)H(4)(CN)(2) afforded 1,3-C(6)H(4)(X)X' (X =CC(Ph)N(SiMe3)Li(tmeda)N(SiMe3)CH; X' = CN(SiMe3)Li(tmeda)NC(Ph)=C(H)SiMe3)(9). Interaction of A and 2[1,2-C(6)H(4)(CN)(2)] gave the bis(lithio-isoindoline) derivative [C6H4C(=NH)N{Li(OEt2)}C=C(SiMe3)C(Bu(t))=N(SiMe3)]2 (5). The X-ray structures of 2, 3, 5 and 9 are presented, and reaction pathways for each reaction are suggested.     

Alkali metal complexes of a naphthylamine-substituted phosphanide

The reaction between {(Me3Si)2CH}PCl2 and one equivalent of [C10H6-8-NMe2]Li, followed by in situ reduction with LiAlH4, gives the secondary phosphane {(Me3Si)2CH}(C10H6-8-NMe2)PH(1) in good yield as a colourless crystalline solid. Metalation of 1 with Bu(n)Li in diethyl ether gives the lithium phosphanide [{[{(Me3Si)2CH}(C10H6-8-NMe2)P]Li}2(OEt2)](2), which undergoes metathesis with either NaOBu(t) or KOBu(t) to give the heavier alkali metal derivatives [[{(Me3Si)2CH}(C10H6-8-NMe2)P]-Na(tmeda)](3) and [[{(Me3Si)2CH}(C10H6-8-NMe2)P]K(pmdeta)](4), after recrystallisation in the presence of the corresponding amine co-ligand [tmeda = N,N,N',N'-tetramethylethylenediamine, pmdeta = N,N,N',N",N"-pentamethyldiethylenetriamine]. Compounds 2-4 have been characterised by 1H, 13C{1H} and 31P{1H} NMR spectroscopy, elemental analyses and X-ray crystallography. Dinuclear 2 crystallises with the phosphanide ligands arranged in a head-to-head fashion and is subject to dynamic exchange in toluene solution; in contrast, compounds 3 and 4 crystallise as discrete monomers which exhibit no dynamic behaviour in solution. DFT calculations on the model compound [{[(Me)(C10H6-8-NMe2)P]Li},(OMe2)] (2a) indicate that the most stable head-to-head form is favoured by 15.0 kcal mol(-1) over the corresponding head-to-tail form.     

Synthesis, structures and stabilities of thioanisole-functionalised phosphido-borane complexes of the alkali metals

Treatment of the secondary phosphine {(Me(3)Si)(2)CH}PH(C(6)H(4)-2-SMe) with BH(3)·SMe(2) gives the corresponding phosphine-borane {(Me(3)Si)(2)CH}PH(BH(3))(C(6)H(4)-2-SMe) (9) as a colourless solid. Deprotonation of 9 with n-BuLi, PhCH(2)Na or PhCH(2)K proceeds cleanly to give the corresponding alkali metal complexes [[{(Me(3)Si)(2)CH}P(BH(3))(C(6)H(4)-2-SMe)]ML](n) [ML = Li(THF), n = 2 (10); ML = Na(tmeda), n = ∞ (11); ML = K(pmdeta), n = 2 (12)] as yellow/orange crystalline solids. X-ray crystallography reveals that the phosphido-borane ligands bind the metal centres through their sulfur and phosphorus atoms and through the hydrogen atoms of the BH(3) group in each case, leading to dimeric or polymeric structures. Compounds 10-12 are stable towards both heat and ambient light; however, on heating in toluene solution in the presence of 10, traces of free phosphine-borane 9 are slowly converted to the free phosphine {(Me(3)Si)(2)CH}PH(C(6)H(4)-2-SMe) (5) with concomitant formation of the corresponding phosphido-bis(borane) complex [{(Me(3)Si)(2)CH}P(BH(3))(2)(C(6)H(4)-2-SMe)]Li (14).     

Reduction of carbodiimides by samarium(II) bis(trimethylsilyl)amides-formation of oxalamidinates and amidinates through C-C coupling or C-H activation

The reaction of [Sm{N(SiMe3)2}2(THF)2] (THF=tetrahydrofuran) with carbodiimides RN=C=NR (R=Cy, C6H3-2,6-iPr2) led to the formation of dinuclear SmIII complexes via differing C-C coupling processes. For R=Cy, the product [{(Me3Si)2N}2Sm(micro-C2N4Cy4)Sm{N(SiMe3)2}2] (1) has an oxalamidinate [C2N4Cy4]2- ligand resulting from coupling at the central C atoms of two CyNCNCy moieties. In contrast, for R=C6H3-2,6-iPr2, H transfer and an unusual coupling of two iPr methine C atoms resulted in a linked formamidinate complex, [{(Me3Si)2N}2Sm{micro-(RNC(H)N(Ar-Ar)NC(H)NR)}Sm{N(SiMe3)2}2] (2) (Ar-Ar=C6H3-2-iPr-6-C(CH3)2C(CH3)2-6'-C6H3-2'-iPr). Analogous reactions of RN=C=NR (R=Cy, C6H3-2,6-iPr2) with the SmII "ate" complex [Sm{N(SiMe2)3Na] gave 1 for R=Cy, but a novel C-substituted amidinate complex, [(THF)Na{N(R)C(NR)CH2Si(Me2)N(SiMe3)}Sm{N(SiMe3)2}2] (3), for R=C6H3-2,6-iPr2, via gamma C-H activation of a N(SiMe3)2 ligand.     

Alkali metal complexes of sterically demanding amino-functionalized secondary phosphanide ligands

The reaction between {(Me(3)Si)(2)CH}PCl(2) (4) and one equivalent of either [C(6)H(4)-2-NMe(2)]Li or [2-C(5)H(4)N]ZnCl, followed by in situ reduction with LiAlH(4) gives the secondary phosphanes {(Me(3)Si)(2)CH}(C(6)H(4)-2-NMe(2))PH (5) and {(Me(3)Si)(2)CH}(2-C(5)H(4)N)PH (6) in good yields as colourless oils. Metalation of 5 with Bu(n)Li in THF gives the lithium phosphanide [[{(Me(3)Si)(2)CH}(C(6)H(4)-2-NMe(2))P]Li(THF)(2)] (7), which undergoes metathesis with either NaOBu(t) or KOBu(t) to give the heavier alkali metal derivatives [[{(Me(3)Si)(2)CH}(C(6)H(4)-2-NMe(2))P]Na(tmeda)] (8) and [[{(Me(3)Si)(2)CH}(C(6)H(4)-2-NMe(2))P]K(pmdeta)] (9) after recrystallization in the presence of the corresponding amine co-ligand [tmeda = N,N,N',N'-tetramethylethylenediamine, pmdeta = N,N,N',N',N'-pentamethyldiethylenetriamine]. The pyridyl-functionalized phosphane 6 undergoes deprotonation on treatment with Bu(n)Li to give a red oil corresponding to the lithium compound [{(Me(3)Si)(2)CH}(2-C(5)H(4)N)P]Li (10) which could not be crystallized. Treatment of this oil with NaOBu(t) gives the sodium derivative [{[{(Me(3)Si)(2)CH}(2-C(5)H(4)N)P]Na}(2) x (Et(2)O)](2) (11), whilst treatment of with KOBu(t), followed by recrystallization in the presence of pmdeta gives the complex [[{(Me(3)Si)(2)CH}(2-C(5)H(4)N)P]K(pmdeta)](2) (12). Compounds 5-12 have been characterised by (1)H, (13)C{(1)H} and (31)P{(1)H} NMR spectroscopy and elemental analyses; compounds 7-9, and 12 have additionally been characterised by X-ray crystallography. Compounds 7-9 crystallize as discrete monomers, whereas 11 crystallizes as an unusual dimer of dimers and 12 crystallizes as a dimer with bridging pyridyl-phosphanide ligands.     

Synthesis, structures and reactions of lithium complexes of [(o-RCHC6H4)PPh2=NSiMe3]-(R = H, SiMe3) ligands

N-Trimethylsilyl o-methylphenyldiphenylphosphinimine, (o-MeC6H4)PPh2=NSiMe3 (1), was prepared by reaction of Ph2P(Br)=NSiMe3 with o-methylphenyllithium. Treatment of 1 with LiBun and then Me3SiCl afforded (o-Me3SiCH2C6H4)PPh2=NSiMe3 (2). Lithiations of both 1 and 2 with LiBu(n) in the presence of tmen gave crystalline lithium complexes [Li{CH(R)C6H4(PPh(2=NSiMe3)-.tmen](3, R = H; 4, R = SiMe3). From the mother liquor of 4, traces of the tmen-bridged complex [Li{CH(SiMe3)C6H4(PPh2=NSiMe3)-2}]2(mu-tmen) (5) were obtained. Reaction of 2 with LiBun in Et2O yielded complex [Li{CH(SiMe3)C6H4(PPh2=NSiMe3)-2}.OEt2] (6). Reaction of lithiated with Me2SiCl2 in a 2:1 molar ratio afforded dimethylsilyl-bridged compound Me2Si[CH2C6H4(PPh2=NSiMe3)-2]2 (7). Lithiation of 7 with two equivalents of LiBun in Et2O yielded [Li2{(CHC6H4(PPh2=NSiMe3)-2)2SiMe2}.0.5OEt2](8.0.5OEt2). Treatment of 4 with PhCN formed a lithium enamide complex [Li{N(SiMe3)C(Ph)CHC6H4(PPh2=NSiMe3)-2}.tmen] (9). Reaction of two equivalents of 5 with 1,4-dicyanobenzene gave a dilithium complex [{Li(OEt2)2}2(1,4-{C(N(SiMe3)CHC6H4(PPh2=NSiMe3)-2}2C6H4)] (10). All compounds were characterised by NMR spectroscopy and elemental analyses. The structures of compounds 2, 3, 5, 6 and 9 have been determined by single crystal X-ray diffraction techniques.     

Peripheral SH-functionalisation of carbosilane dendrimers including the synthesis of the model compound dimethylbis(propanethiol)silane and their interaction with rhodium complexes

Treatment of the allyl-containing compounds Me2Si(CH2CHCH2)2 and MeSi(CH2CHCH2)3 with thioacetic acid in the presence of AIBN gave Me2Si[(CH2)3SC(O)CH3]2 and MeSi[(CH2)3SC(O)CH3]3, respectively, which were reduced with LiAlH4 to the dithiols Me2Si[(CH2)3SH]2(3) and MeSi[(CH2)3SH]3(4). This protocol was applied to the first and second generations of the doubly and triply-branched carbosilane allyl dendrimers, Si[(CH2)3SiMe(CH2CHCH2)2]4(G(1)allyl-8), Si[(CH2)3SiMe{(CH2)3SiMe(CH2CHCH2)2}2]4(G(2)allyl-16), Si[(CH2)3Si(CH2CHCH2)3]4(G(1)allyl-12), and Si[(CH2)3Si{(CH2)3Si(CH2CHCH2)3}3]4(G(2)allyl-36) to give the corresponding SH functionalised surface dendrimers Si[(CH2)3SiMe(CH2CH2CH2SH)2]4(G(1)SH-8), G(2)SH-16, G(1)SH-12, and G(2)SH-36. Reactions of 3 with [M(acac)(diolefin)](M = Rh, Ir; diolefin = 1,5-cyclooctadiene, 2,5-norbornadiene) gave the compounds of the type [M2(mu-Me2Si[(CH2)3S]2)(diolefin)2]n. These diolefin complexes are octanuclear (n= 4) in solution while the complex [Rh2(mu-Me2Si[(CH2)3S]2)(cod)2]n(5) is tetranuclear in the solid state. The structure of 5, solved by X-ray diffraction methods, consists of a 20-membered metallomacrocycle formed by two dimethylbis(propylthiolate)silane moieties bridging four fragments Rh(cod) in a mu2 fashion through the sulfur atoms. Treatment of [Rh(acac)(CO)2] with 3 gave [Rh2(mu-Me2Si[(CH2)3S]2)(CO)4]n, which is a mixture of tetra (n= 2) and octanuclear (n= 4) complexes in a 2 : 1 ratio in solution, while the related complex [Rh2(mu-Me2Si[(CH2)3S]2)(CO)2(PPh3)2]2 is tetranuclear. Reactions of [Rh(acac)(L-L)](L-L = cod, (CO)2, (CO)(PPh3)) with 4 and the dendrimers G(1)SH-8, G(2)SH-16, and G(1)SH-12, gave microcrystalline solids of formulae [Rh3(MeSi[(CH2)3S]3)(L-L)3]n, [Si[(CH2)3SiMe{(CH2)3SRh(cod)}2]4]n([G(1)Rh(cod)-8]n), [Si[(CH2)3Si{(CH2)3SRh(cod)}3]4]n([G(1)Rh(cod)-12]n), etc., which presumably are tridimensional coordination polymers.     

Unique sigma-bond metathesis of silylalkynes promoted by an ansa-dimethylsilyl and oxo-bridged uranium metallocene

The tetrachloride salt of uranium reacts with 1 equiv of the lithium ligand Li2[(C5Me4)2SiMe2] in DME to form the complex [eta5-(C5Me4)2SiMe2]UCl2.2LiCl.2DME (1), which undergoes a rapid hydrolysis in toluene to yield the dimeric bridged monochloride, monooxide complex [{[eta5-(C5Me4)2SiMe2]UCl}2(mu-O)(mu-Cl)*Li*1/2DME]2 (2). Metathesis of 2 with BuLi in DME gives the mono-bridged dibutyl complex {[eta5-(C5Me4)2SiMe2]UBu}2(mu-O) (3). Complex 2 was characterized by solid-state X-ray analysis. Complex 3 was found to be an active catalyst for the disproportionation metathesis of TMSCCH (TMS = SiMe3) and the cross-metathesis of TMSCCH or TMSCCTMS with various terminal alkynes. The metathesis of TMSCCH gives TMSCCTMS and HCCH, whereas the cross-metathesis of TMSCCH or TMSCCTMS with terminal alkynes (RCCH) yields TMSCCTMS, TMSCCR, and HCCH. In addition, TMSCCCH3 also was found to react with tBuCCH, yielding TMSCCBut and CH3CCH. A plausible mechanism for the catalytic process is presented.     

Structural varieties in heterobimetallic lanthanide disiloxanediolates: "inorganic metallocenes" versus in-plane metallacrowns

The previously proposed concept of "inorganic metallocenes" of group 3 and rare-earth elements has been tested by preparing a series of novel disiloxanediolates with metals displaying different ionic radii. For the smaller scandium and yttrium, approximately planar arrangements of the disiloxanediolate frameworks with solvent and chloride ligands in trans positions were found. Thus, the compounds [{(Ph2SiO)2O}2{Li(DME)}2]ScCl(THF/DME) (2; DME=1,2-dimethoxyethane and THF=tetrahydrofuran) and [{(Ph2SiO)2O}2{Li(THF)2}2]YCl(THF) (3) can be described as heterobimetallic inorganic ring systems or metallacrown complexes with "in-plane" coordination of the metal. In contrast, "out-of-plane" geometries with cis coordination of additional ligands were identified in the praseodymium derivatives [{(Ph2SiO)2O}2{Li(THF)2}{Li(THF)}]Pr(micro-Cl)2Li(THF)2 (4) and [{(Ph2SiO)2O}2{Li(DME)}2]PrCl(DME) (5). These compounds can be viewed as analogues of the known metallocene derivatives (C5Me5)2Pr(micro-Cl)2Li(THF)2 and (C5Me5)2PrCl(THF). The molecular structures of 2-5 have been determined by X-ray diffraction.     

Synthesis and structural characterization of a series of lanthanide(II) amides: steric effect of amido ligand

The synthesis and structures of a series of lanthanide(II) and lanthanide(III) complexes supported by the amido ligand N(SiMe3)Ar were described. Several lanthanide(III) amide chlorides were synthesized by a metathesis reaction of LnCl3 with lithium amide, including {[(C6H5)(Me3Si)N]2YbCl(THF)}2.PhCH3 (1), [(C6H3-iPr2-2,6)(SiMe3)N]2YbCl(mu-Cl)Li(THF)3.PhCH3 (4), [(C6H3-iPr2-2,6)(SiMe3)N]YbCl2(THF)3 (6), and [(C6H3-iPr2-2,6)(SiMe3)N]2SmCl3Li2(THF)4 (7). The reduction reaction of 1 with Na-K alloy afforded bisamide ytterbium(II) complex [(C6H5)(Me3Si)N]2Yb(DME)2 (2). The same reaction for Sm gave an insoluble black powder. An analogous samarium(II) complex [(C6H5)(Me3Si)N]2Sm(DME)2 (3) was prepared by the metathesis reaction of SmI2 with NaN(C6H5)(SiMe3). The reduction reaction of ytterbium chloride 4 with Na-K alloy afforded monoamide chloride {[(C6H3-iPr2-2,6)(SiMe3)N]Yb(mu-Cl)(THF)2}2 (5), which is the first example of ytterbium(II) amide chloride, formed via the cleavage of the Yb-N bond. The same reduction reaction of 7 gave a normal bisamide complex [(C6H3-iPr2-2,6)(SiMe3)N]2Sm(THF)2 (8) via Sm-Cl bond cleavage. This is the first example for the steric effect on the outcome of the reduction reaction in lanthanide(II) chemistry. 5 can also be synthesized by the Na/K alloy reduction reaction of 6. All of the complexes were fully characterized including X-ray diffraction for 1-7.     

Cube-type nitrido complexes containing titanium and zinc/copper

Several azaheterometallocubane complexes containing [MTi3N4] cores have been prepared by the reaction of [{Ti(eta5-C5Me5)(mu-NH)}3(mu3-N)] (1) with zinc(II) and copper(I) derivatives. The treatment of 1 with zinc dichloride in toluene at room temperature produces the adduct [Cl2Zn{(mu3-NH)3Ti3(eta5-C5Me5)3(mu3-N)}] (2). Attempts to crystallize 2 in dichloromethane gave yellow crystals of the ammonia adduct [(H3N)Cl2Zn{(mu3-NH)Ti3(eta5-C5Me5)3(mu-NH)2(mu3-N)}] (3). The analogous reaction of 1 with alkyl, (trimethylsilyl)cyclopentadienyl, or amido zinc complexes [ZnR2] leads to the cube-type derivatives [RZn{(mu3-N)(mu3-NH)2Ti3(eta5-C5Me5)3(mu3-N)}] (R = CH2SiMe3 (5), CH2Ph (6), Me (7), C5H4SiMe3 (8), N(SiMe3)2 (9)) via RH elimination. The amido complex 9 decomposes in the presence of ambient light to generate the alkyl derivative [{Me3Si(H)N(Me)2SiCH2}Zn{(mu3-N)(mu3-NH)2Ti3(eta5-C5Me5)3(mu3-N)}] (10). The chloride complex 2 reacts with lithium cyclopentadienyl or lithium indenyl reagents to give the cyclopentadienyl or indenyl zinc derivatives [RZn{(mu3-N)(mu3-NH)2Ti3(eta5-C5Me5)3(mu3-N)}] (R = C5H5 (11), C9H7 (12)). Treatment of 1 with copper(I) halides in toluene at room temperature leads to the adducts [XCu{(mu3-NH)3Ti3(eta5-C5Me5)3(mu3-N)}] (X = Cl (13), I (14)). Complex 13 reacts with lithium bis(trimethylsilyl)amido in toluene to give the precipitation of [{Cu(mu4-N)(mu3-NH)2Ti3(eta5-C5Me5)3(mu3-N)}2] (15). Complex 15 is prepared in a higher yield through the reaction of 1 with [{CuN(SiMe3)2}4] in toluene at 150 degrees C. The addition of triphenylphosphane to 15 in toluene produces the single-cube compound [(Ph3P)Cu{(mu3-N)(mu3-NH)2Ti3(eta5-C5Me5)3(mu3-N)}] (16). The X-ray crystal structures of 3, 8, 9, and 15 have been determined.     

Extremely bulky amido-group 14 element chloride complexes: potential synthons for low oxidation state main group chemistry

The preparation of a series of extremely bulky secondary amines, Ar*N(H)SiR(3) (Ar* = C(6)H(2){C(H)Ph(2)}(2)Me-2,6,4; R(3) = Me(3), MePh(2) or Ph(3)) is described. Their deprotonation with either LiBu(n), NaH or KH yields alkali metal amide complexes, several monomeric examples of which, [Li(L){N(SiMe(3))(Ar*)}] (L = OEt(2) or THF), [Na(THF)(3){N(SiMe(3))(Ar*)}] and [K(OEt(2)){N(SiPh(3))(Ar*)], have been crystallographically characterised. Reactions of the lithium amides with germanium, tin or lead dichloride have yielded the first structurally characterised two-coordinate, monomeric amido germanium(II) and tin(II) chloride complexes, [{(SiR(3))(Ar*)N}ECl] (E = Ge or Sn; R = Me or Ph), and a chloride bridged amido-lead(II) dimer, [{[(SiMe(3))(Ar*)N]Pb(μ-Cl)}(2)]. DFT calculations on [{(SiMe(3))(Ar*)N}GeCl] show its HOMO to exhibit Ge lone pair character and its LUMO to encompass its Ge based p-orbital. A series of bulky amido silicon(IV) chloride complexes have also been prepared and several examples, [{(SiR(3))(Ar*)N}SiCl(3)] (R(3) = Me(3), MePh(2)) and [{(SiMe(3))(Ar*)N}SiHCl(2)], were crystallographically characterised. The sterically hindered group 14 complexes reported in this study hold significant potential as precursors for kinetically stabilised low oxidation state and/or low coordination number group 14 complexes.     

Synthesis and structures of a 3-sila-beta-diketiminatomagnesium bromide, ketenimide and triflate

The crystalline compounds [Mg(Br)(L)(thf)].0.5Et2O [L = {N(R)C(C6H3Me2-2,6)}2SiR, R = SiMe3] (1), [Mg(L){N=C=C(C(Me)=CH)2CH2}(D)2] [D = NCC6H3Me2-2,6 (2), thf (3)] and [{Mg(L)}2{mu-OSO(CF3)O-[mu}2] (4) were prepared from (a) Si(Br)(R){C(C6H3Me2-2,6)=NR}2 and Mg for (1), (b) [Mg(SiR3)2(thf)2] and 2,6-Me2C6H3CN (5 mol for (2), 3 mol for (3)), and (c) (2) + Me3SiOS(O)2CF3 for (4); a coproduct from (c) is believed to have been the trimethylsilyl ketenimide Me3SiN=C=C{C(Me)=CH}2CH2 (5).     

Half-sandwich o-N,N-dimethylaminobenzyl complexes over the full size range of group 3 and lanthanide metals. synthesis, structural characterization, and catalysis of phosphine P--H bond addition to carbodiimides

The acid-base reactions between the rare-earth metal (Ln) tris(ortho-N,N-dimethylaminobenzyl) complexes [Ln(CH2C(H4NMe2-o)3] with one equivalent of the silylene-linked cyclopentadiene-amine ligand (C5Me4H)SiMe2NH(C6H2Me3-2,4,6) afforded the corresponding half-sandwich aminobenzyl complexes [{Me2Si(C5Me4)(NC6H2Me3-2,4,6)}Ln(CH2C6H4NMe2-o)(thf)] (2-Ln) (Ln=Y, La, Pr, Nd, Sm, Gd, Lu) in 60-87 % isolated yields. The one-pot reaction between ScCl(3) and [Me2Si(C5Me4)(NC6H2Me3-2,4,6)]Li2 followed by reaction with LiCH2C6H4NMe2-o in THF gave the scandium analogue [{Me2Si(C5Me4)(NC6H2Me3-2,4,6)}Sc(CH2C6H4NMe2-o)] (2-Sc) in 67 % isolated yield. 2-Sc could not be prepared by the acid-base reaction between [Sc(CH2C6H4NMe2-o)3] and (C5Me4H)SiMe2NH(C6H2Me3-2,4,6). These half-sandwich rare-earth metal aminobenzyl complexes can serve as efficient catalyst precursors for the catalytic addition of various phosphine P--H bonds to carbodiimides to form a series of phosphaguanidine derivatives with excellent tolerability to aromatic carbon-halogen bonds. A significant increase in the catalytic activity was observed, as a result of an increase in the metal size with a general trend of La>Pr, Nd>Sm>Gd>Lu>Sc. The reaction of 2-La with 1 equiv of Ph2PH yielded the corresponding phosphide complex [{Me2Si(C5Me4)(NC6H2Me3-2,4,6)}La(PPh2)(thf)2] (4), which, on recrystallization from benzene, gave the dimeric analogue [{Me2Si(C5Me4)(NC6H2Me3-2,4,6)}La(PPh2)]2 (5). Addition of 4 or 5 to iPrN=C=NiPr in THF yielded the phosphaguanidinate complex [{Me2Si(C5Me4)(NC6H2Me3-2,4,6)}La{iPrNC(PPh2)NiPr}(thf)] (6), which, on recrystallization from ether, afforded the ether-coordinated structurally characterizable analogue [{Me2Si(C5Me4)(NC6H2Me3-2,4,6)}La{iPrNC(PPh2)NiPr}(OEt2)] (7). The reaction of 6 or 7 with Ph2PH in THF yielded 4 and the phosphaguanidine iPrN=C(PPh2)NHiPr (3a). These results suggest that the catalytic formation of a phosphaguanidine compound proceeds through the nucleophilic addition of a phosphide species, which is formed by the acid-base reaction between a rare-earth metal o-dimethylaminobenzyl bond and a phosphine P--H bond, to a carbodiimide, followed by the protonolysis of the resultant phosphaguanidinate species by a phosphine P--H bond. Almost all of the rare earth complexes reported this paper were structurally characterized by X-ray diffraction studies.     

N,N'-diisopropyl-N'-bis(trimethylsilyl)guanidinate ligand as a supporting coordination environment in yttrium chemistry. Synthesis, structure, and properties of complexes [(Me(3)Si)(2)NC(Ni-Pr)(2)]YCl(2)(THF)(2), [(Me(3)Si)(2)NC(Ni-Pr)(2)]Y(CH(2)SiMe(3))(2)(THF)(2), and [(Me(3)Si)(2)NC(Ni-Pr)(2)]Y[(mu-H)(mu-Et)(2)BEt](2)(THF)

The reaction of anhydrous YCl3 with an equimolar amount of lithium N,N'-diisopropyl-N' '-bis(trimethylsilyl)guanidinate, Li[(Me3Si)2NC(Ni-Pr)2], in tetrahydrofuran (THF) afforded the monomeric monoguanidinate dichloro complex {(Me3Si)2NC(Ni-Pr)2}YCl2(THF)2 (1). Alkylation of complex 1 with 2 equiv of LiCH2SiMe3 in hexane at 0 degrees C yielded the monomeric salt-free dialkyl complex {(Me3Si)2NC(Ni-Pr)2}Y(CH2SiMe3)2(THF)2 (2). The bis(triethylborohydride) complex [(Me3Si)2NC(Ni-Pr)2]Y[(mu-H)(mu-Et)2BEt]2(THF) (5) was prepared by the reaction of complex 1 with 2 equiv of LiBEt3H in a toluene-THF mixture at 0 degrees C. The complexes 1, 2, and 5 were structurally characterized. Complex 2 as well as the systems 2-Ph3B, 2-Ph3B-MAO, and 1-MAO (MAO = methylaluminoxanes) in toluene were inactive in ethylene polymerization, while the product obtained in situ from the reaction of complex 2 with a 2-fold molar excess of PhSiH3 in toluene polymerized ethylene with moderate activity.     

Group 13 organoderivatives supported on a metallic oxide model

The [{TiCp*(micro-O)}3(mu3-CH)] (1) metalloligand, (Cp* = eta5-C5Me5), coordinates in a 1:1 ratio to [AlMe3] or 9-BBN to give [{Me3Al}{(mu3-O)(mu-O)2(TiCp)2(TiCp)3(mu3-CH)}](2) or [{(C8H14)B}(mu-H) {(mu3-O)(mu-O)2(TiCp*)3(mu3-CH)}](4), respectively, partial hydrolysis of 2 leads to the new hydroxo-aluminium derivative [{MeAl} {(mu-OH)(mu3-O)}2{(mu-O)2(TiCp*)3-(mu3-CH)}2](3).     

Synthesis and structures of some heterometallic [(Li, Y)2, (M3, Ce) (M = Li or Na), (Li, Zr2) and (Li, Zr)4] oligomeric diamides derived from 1,2-bis(neopentylamino)benzene

The following crystalline, X-ray-characterised heterometallic oligomeric diamides have been prepared in good yield under mild conditions in diethyl ether from the dilithio or disodio derivative of the N,N'-dineopentyl-1,2-diaminobenzene [{N(H)(CH2Bu(t))}2C6H4-1,2] (abbreviated as H2L):[Y(L)(mu-Cl)2Li(OEt2)2]2 (1), [Li(OEt2)2Li(mu2-Cl)4(mu3-Cl)2{Zr(L)}2]2 (2), [Zr(L)2(mu-Cl){Li(OEt2)2}(mu2-Cl)2Zr(L)] (3), [Ce{(mu-L)M}3(OEt2)(1/2)] (3M = Li(1.82)Na(1.18)) (4), [Ce{(mu-L)Na}3(OEt2)] (5) and [Ce{(mu-L)Na}3] (6). Compounds 1-3 were obtained from Li2(L) and YCl3 (the colourless 1) or ZrCl4 (the red 2 and 3), while the red 4 and 5 were isolated from CeCl3 and M2(L) (3M = Li(1.82)Na(1.18)) (4) or Na2(L) (5). Attempted oxidation of 5 with Br2 in hexane yielded the black 6. The ligand is N,N'-chelating to each of the d- or f-block metals in 1-6; and in 4-6 L is also acting as a bridge between Ce and the alkali metal, to which L is thus also chelating.     

Unusual inorganic ring systems of scandium and yttrium containing group 13 Metals: coordination of monomeric Me(2)InOMe to yttrium

Novel transformations of lanthanide(III) disiloxanediolates with group 13 metal trialkyls are reported. Treatment of the scandium metallacrown complex [{(Ph2SiO)2O}2{Li(DME)}2]ScCl.THF (1) with AlMe3 resulted in an Li-Al exchange reaction and the formation of the heterotrimetallic inorganic ring system [{(Ph2SiO)2O}2{Li(THF)2}AlMe2]ScCl.THF (2). The related yttrium metallacrown [{(Ph2SiO)2O}2{Li(THF)2}2]YCl.THF (3) reacts with InMe3 under the formation of the heterobimetallic Y/In disiloxanediolate complex [{(Ph2SiO)2O}2{InMe2(OMe)}2InMe2]Y (4). In the latter, two monomeric Me2InOMe ligands are stabilized through coordination to yttrium.     

Manipulation of molecular aggregation and supramolecular structure using self-assembled lithium mixed-anion complexes

A set of zero-, one-, two-, and three-dimensional materials have been synthesized by systematically varying the stoichiometry of the two components 2,4,6-Me3-C6H2OLi (ArOLi) and Me2N(CH2)(2)OLi (ROLi) within single aggregates, while using 1,4-dioxane (diox) as a ditopic linker. The homoleptic complex [{(ArOLi)4 x (diox)2} superset3(diox)](infinity) 1 forms a 3D diamondoid extended structure, where Li4O4 cubanes act as tetrahedral nodes. Attempts to rationally alter the dimensionality of the network through the sequential replacement of ArOLi vertices by potentially chelating ROLi units have succeeded. The mixed-anion complexes [{(ROLi)(ArOLi)3 x (diox)(1.5)} superset1/2(C6H14)](infinity) 2 and [(ROLi)4(ArOLi)2 x (diox)](infinity) 4 , adopt 2D hexagonal net and 1D chain structures respectively. Furthermore, the two complexes [{(ROLi)3(ArOLi)3 x (diox)(0.5)}(C6H14)](infinity) 3 and [(ROLi) 5(ArOLi) x (diox)(0.5)](infinity) 5 both form unusual 0D molecular dumbbell structures in the solid state. Incorporation of multiple ROLi units in the mixed-anion complexes not only results in reducing the number of possible sites for polymer extension through chelation, but also changes the aggregation state of the building block from tetrametallic Li4O4 units to hexametallic Li6O6 units.