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.     

Synthesis and structures of some bimetallic (Li/Ca, Li/Zn, Li/Li) diamides derived from 1,2-bis(neopentylamino)benzene and of Li2[{N(SiMe2NPr(i)2)}2C6H4-1,2](thf)3

The following crystalline, or microcrystalline (4), metal diamides have been prepared under mild conditions from the N,N'-disubstituted 1,2-diaminobenzene [{N(R)H}2C6H4-1,2] (H(2): R = CH2But; H2L': R = SiMe2NPri2): [Li(thf)(mu-L)(mu-I)Ca(thf)] (1), [Li(thf)4][{Zn(mu-L)}3(mu3-Cl)] (2), [Li(thf)4][Zn(L)2] (3), [{Li(OEt2)(mu-L)Zn}2(mu-L)] (4), [Li(OEt2)(mu-L)Zn(mu-L)Zn(LH)] (5) and [Li(thf)(mu-L')Li(thf)2] (6). Compounds 1-5 were obtained from [Li2(L)] and CaI2 (1) or ZnCl2 (2-5) while 6 was derived from H2(L') and LiBun. Compound 5 was isolated as a very minor by-product from the synthesis of 4, and is assumed to have been formed therefrom by adventitious hydrolysis. The green salt 3 was paramagnetic with the negative charge uniformly delocalised on the two ligands. The other compounds were colourless and diamagnetic. The X-ray structures of each, except 4, are reported and discussed.     

The beta-dialdiminato ligand [{N(C6H3Pri(2)-2,6)C(H)}2CPh]-: the conjugate acid and Li, Al, Ga and In derivatives

The synthesis of the following crystalline complexes is described: [Li(L)(thf)2] (), [Li(L)(tmeda)] (), [MCl2(L)] [M=Al (), Ga ()], [In(Cl)(L)(micro-Cl)2Li(OEt2)2] (), [In(Cl)(L){N(H)C6H3Pri(2)-2,6}] (), [In(L){N(H)C6H3Pri(2)-2,6}2] (), [{In(Cl)(L)(micro-OH)}2] (), [L(Cl)In-In(Cl)(L)] () (the thf-solvate, the solvate-free and the hexane-solvate), [{In(Cl)L}2(micro-S)] () and [InCl2(L)(tmeda)] () ([L]-=[{N(C6H3Pri(2)-2,6)C(H)}2CPh]-). From H(L) (), via Li(L) in Et2O, and thf, tmeda, AlCl3, GaCl3 or InCl3 there was obtained , , , or , respectively in excellent yield. Compound was the precursor for each of , and [{InCl3(tmeda)2{micro-(OSnMe2)2}}] () by treatment with one () or two () equivalents of K[N(H)(C6H3Pri(2)-2,6)], successively Li[N(SiMe3)(C6H3Pri(2)-2,6)] and moist air (), Na in thf (), tmeda (), or successively tmeda and Me3SnSnMe3 (). Crystals of (with an equivalent of In) and were obtained from InCl or thermolysis of [In(Cl)(L){N(SiMe3)(C6H3Pri(2)-2,6)}] () {prepared in situ from and Li[N(SiMe3)(C6H3Pri(2)-2,6)] in Et2O}, respectively. Compound was obtained from a thf solution of and sulfur. X-Ray data for crystalline , , , , , and are presented. The M(L) moiety in each (not the L-free ) has the monoanionic L ligated to the metal in the N,N'-chelating mode. The MN1C1C2C3N2 six-membered M(L) ring is pi-delocalised and has the half-chair (, and ) or boat (, and ) conformation.     

Synthesis and structures of selected benzamidinates of Li, Na, Al, Zr and Sn(II) using the C1-symmetric ligands [N(SiMe3)C(C6H4Me-4 or Ph)NPh]-

Several compounds based on the C(1)-symmetric ligands [N(R)C(Ar)NPh]- [abbreviated as B1 (Ar = C(6)H(4)Me-4) or B2 (Ar = Ph), R = SiMe(3)] are reported. They are the crystalline metal benzamidinates [Li(mu:kappa2-B1)(OEt2)](2) (1), [Al(kappa2-B1)2Me] (2), [Al(kappa2-B1)2X] [X = Cl/Me, 1 : 1 (3)], [Sn(kappa2-B1)2] (4), Zr(kappa2-B1)2Cl2 (5), [Zr(kappa2-B1)3Cl] (6), [Na(mu:kappa2-B1)(tmeda)]2 (7), K[B1] (8), Li(B2)(OEt2) (9) and Zr(kappa2-B1)3Cl (10) and the known benzamidine Z-H2NC(C6H4Me-4) = NPh (11). They were prepared by (i) insertion of the nitrile 4-MeC6H4CN (1, 7, 8, 11) or PhCN (9) into the appropriate M-N(R')Ph [R' = R and M = Li (1, 9), Na (7), K (8)] bond and subsequent hydrolysis for 11 [R' = H and M = Li], or (ii) a ligand transfer reaction using the lithium amidinate 1 and Al(Me)2Cl (2, 3), SnCl2 (4) or ZrCl4 (5, 6), or Li(B2) and ZrCl4 (10). The X-ray structures of 1, 2, 3, 4, 6b (i.e..3PhMe) 7, and 11 are presented. Exploratory polymerisation experiments are described, using 2, 5 or 6 as a procatalyst with methylaluminoxane (MAO) (Al : Zr ca. 500 : 1) as promoter. Thus toluene solutions were exposed to C2H4 under ambient conditions; while 2 was unresponsive, 5 and 6 showed modest activity in the formation of polyethylene.     

Synthesis and structures of the [benzamidinato]3- complexes Li3(tmeda)(L1)]2 and [Li(thf)4][Li5(L2)(OEt2)2] [L1 = N(SiMe3)C(Ph)N(SiMe3) and L2 = N(SiMe3)C(C6H4-4)NPh

Reduction at ambient temperature of each of the lithium benzamidinates [Li(L(1))(tmeda)] or [{Li(L(2))(OEt(2))(2)}(2)] with four equivalents of lithium metal in diethyl ether or thf furnished the brown crystalline [Li(3)(L(1))(tmeda)] (1) or [Li(thf)(4)][Li(5)(L(2))(2)(OEt(2))(2)] (2), respectively. Their structures show that in each the [N(R(1))C(R(3))NR(2)](3-) moiety has the three negative charges largely localised on each of N, N' and R = Aryl); a consequence is that the "aromatic" 2,3- and 5,6-CC bonds of R(3) approximate to being double bonds. Multinuclear NMR spectra in C(6)D(6) and C(7)D(8) show that 1 and 2 exhibit dynamic behaviour. [The following abbreviations are used: L(1) = N(SiMe(3))C(Ph)N(SiMe(3)); L(2) = N(SiMe(3))C(C(6)H(4)Me-4)N(Ph); tmeda = (Me(2)NCH(2)-)(2); thf = tetrahydrofuran.] This reduction is further supported by a DFT analysis.     

Crystalline metal (Li, Mg, Ca, Sr, Ba, Sn, Pb) complexes of the new chelating N,N'-dianionic [1,2-N(R)C6H4(CH2NR)](2-) ligand (R = SiMe3, CH2Bu(t))

2-Aminomethylaniline was converted into the N,N'-bis(pivaloyl) (1) or -bis(trimethylsilyl) (2) derivative, using 2 Bu(t)C(O)Cl or 2 Me(3)SiCl (≡ RCl), respectively, with 2 NEt(3), or for 2 from successively using 2 LiBu(n) and 2 RCl. N,N'-Bis(neopentyl)-2-(aminomethyl)aniline (3) was prepared by LiAlH(4) reduction of 1. From 2 or 3 and 2 LiBu(n), the appropriate dilitiodiamide {2-[{N(Li)R}C(6)H(4){CH(2)N(Li)R}(L)](2) (L absent, 4a; or L = THF, 4b) or the N,N'-bis(neopentyl) analogue (5) of 4a was prepared. Treatment of 4a with 2 Bu(t)NC, 2 (2,6-Me(2)C(6)H(3)NC) or 2 Bu(t)CN (≡ L') furnished the corresponding adduct [2-N{Li(L')R}C(6)H(4){CH(2)N(Li)R}] (4c, 4d or 4e, respectively), whereas 4b with 2 PhCN afforded [2-{N(Li)R}C(6)H(4){CH(2)C(Ph) = NLi(NCPh)}] (6). The dimeric bis(amido)stannylene [Sn{N(R)C(6)H(4)(CH(2)NR)-1,2}](2) (7) was obtained from 4a and [Sn(μ-Cl)NR(2)](2), while the N,N'-bis(neopentyl) analogue 8 of 7 was similarly derived from [Sn(μ-Cl)NR(2)](2) and 5. Reaction of two equivalents of the diamine 2 with Pb(NR(2))(2) yielded 9, the lead homologue of 7. Oxidative addition of sulfur to 7 led to the dimeric bis(diamido)tin sulfide 10. Treatment of 2 successively with 'MgBu(2)' in C(5)H(12) and THF gave [Mg{N(R)C(6)H(4)(CH(2)NR)}(THF)](2) (11a), which by displacement of its THF by an equivalent portion of Bu(t)CN or PhCN produced [Mg{N(R)C(6)H(4)(CH(2)NR)}(CNR')(n)] [R' = Bu(t), n = 1 (11b); R' = Ph, n = 2 (11c)]. The Ca (12), Sr (13) or Ba (14) analogues of the Mg compound 11a were isolated from 2 and either the appropriate compound M(NR(2))(2) (M = Ca, Sr, Ba), or successively 2 LiBu(n) and 2 M(OTos)(2). The new compounds 1-14 were characterized by microanalysis (C, H, N; not for 1, 2, 3, 5), solution NMR spectra, ν(max) (C≡N) (IR for 4c, 4d, 4e, 6, 11b, 11c), selected EI-MS peaks (for 1, 2, 3, 7, 8, 9, 10), and single crystal X-ray diffraction (for 4a, 4b, 11a).     

Reaction of the silylene Si[(NCH2But)2C6H4-1,2] with the alkali metal silylamides M[N(SiMe3)R](M = Li, Na or K; R = SiMe3 or SiMe2Ph)

The thermally stable silylene Si[(NCH(2)Bu(t))(2)C(6)H(4)-1,2] 1 undergoes oxidative addition reactions with the alkali metal silylamides MN(SiMe(3))(2)(M = Li, Na or K) to afford the new alkali metal amides MN(SiMe(3))[(1)SiMe(3)][M = Li (2), Na (3) or K (4)]. Reaction of two equivalents of 1 with LiN(R)(SiMe(3)) leads in a two-step process to the compound LiN[(1)R][(1)SiMe(3)][R = SiMe(2)Ph (5) or SiMe(3) (6)]. Alternatively, 1 reacts with 3 to afford NaN[(1)SiMe(3)](2) (7). The structures of 2-5 and are presented and the formation of 2-7 is discussed.     

Synthesis and structures of crystalline Li, Al and Sn(II) 1-azaallyls and beta-diketiminates derived from [Li{mu,eta3-N(SiMe3)C(Ad)C(H)SiMe3}]2 (Ad = 1-adamantyl)

The crystalline dimeric 1-azaallyllithium complex [Li{mu,eta(3-N(SiMe3)C(Ad)C(H)SiMe3}]2 (1) was prepared from equivalent portions of Li[CH(SiMe3)2] and 1-cyanoadamantane (AdCN). Complex was used as precursor to each of the crystalline complexes 2-8 which were obtained in good yield. By 1-azaallyl ligand transfer, 1 afforded (i) [Al{eta3-N(SiMe3)C(Ad)C(H)SiMe3}{kappa1-N(SiMe3)C(Ad)=C(H)SiMe3-E}Me] (5) with [AlCl2Me](2), (ii) [Sn{eta3-N(SiMe3)C(Ad)C(H)SiMe3}2] (7) with Sn[N(SiMe3)2]2, and (iii) [Li(N{C(Ad)=C(H)SiMe3-E}{Si(NN)SiMe3})(thf)2] (8) with the silylene Si[(NCH(2)Bu(t))2C6H(4)-1,2] [= Si(NN)]. By insertion into the C[triple bond, length as m-dash]N bond of the appropriate cyanoarene RCN, gave the beta-diketiminate [Li{mu-N(SiMe3)C(Ad)C(H)C(R)NSiMe3}]2 [R = Ph (2), C(6)H(4)Me-4 (3)], and yielded [Al{kappa2-N(SiMe3)C(Ad)C(H)C(Ph)NSiMe3}{kappa1-N(SiMe3)C(Ad)=C(H)SiMe3-E}Me] (6). The beta-diketiminate [Al{kappa2-N(SiMe3)C(Ad)C(H)C(Ph)NSiMe3}Me2] (4) was prepared from 2 and [AlClMe2]2. The X-ray structures of 1 and 3-8 are presented. Multinuclear NMR spectra in C6D6 or C6D5CD3 have been recorded for each of 1-8; such data on 8 revealed that in solution two minor isomers were also present.     

High-valent uranium alkyls: evidence for the formation of U(VI)(CH2SiMe3)6

Oxidation of [Li(DME)(3)][U(CH(2)SiMe(3))(5)] with 0.5 equiv of I(2), followed by immediate addition of LiCH(2)SiMe(3), affords the high-valent homoleptic U(V) alkyl complex [Li(THF)(4)][U(CH(2)SiMe(3))(6)] (1) in 82% yield. In the solid-state, 1 adopts an octahedral geometry as shown by X-ray crystallographic analysis. Addition of 2 equiv of tert-butanol to [Li(DME)(3)][U(CH(2)SiMe(3))(5)] generates the heteroleptic U(IV) complex [Li(DME)(3)][U(O(t)Bu)(2)(CH(2)SiMe(3))(3)] (2) in high yield. Treatment of 2 with AgOTf fails to produce a U(V) derivative, but instead affords the U(IV) complex (Me(3)SiCH(2))Ag(μ-CH(2)SiMe(3))U(CH(2)SiMe(3))(O(t)Bu)(2)(DME) (3) in 64% yield. Complex 3 has been characterized by X-ray crystallography and is marked by a uranium-silver bond. In contrast, oxidation of 2 can be achieved via reaction with 0.5 equiv of Me(3)NO, producing the heteroleptic U(V) complex [Li(DME)(3)][U(O(t)Bu)(2)(CH(2)SiMe(3))(4)] (4) in moderate yield. We have also attempted the one-electron oxidation of complex 1. Thus, oxidation of 1 with U(O(t)Bu)(6) results in formation of a rare U(VI) alkyl complex, U(CH(2)SiMe(3))(6) (6), which is only stable below -25 °C. Additionally, the electronic properties of 1-4 have been assessed by SQUID magnetometry, while a DFT analysis of complexes 1 and 6 is also provided.     

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.     

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).     

Reactions of M[CH(SiMe3)2] (M = Na or K) with PhCN, and related chemistry

A number of metal complexes containing one of the following ligands: the 1-azaallyl [N(R)C(Ph)C(H)R]- ([triple bond]L-), the 1,3-diazaallyl([triple bond]LL'-) and the isomeric beta-diketiminate [{N(R)C(Ph)]}2CH]- ( identical with LL-) have been prepared (R = SiMe(3)). These are the crystalline compounds H(LL) (2), Na(LL) (3), [Na(LL)(thf)2] (4), Na(L) (6), [Na(mu-LL')]8 (7), [K(mu-L)(eta6-C6H6)]2 (8), [K(mu-LL')(thf)]2 (9), [K(thf)2(mu-LL)](infinity) (10) and [Ni(LL')2] (11). A new synthesis of Na[C(H)R2] (1) involved Hg[C(H)R2]2 and Na/Hg as reagents. The beta-diketimine 2 was obtained from Li(LL) and cyclopentadiene. Under different conditions compounds 3, 6 and 7 were isolated from 1 and benzonitrile, and compounds 8, 9 and 10 from K[C(H)R2] and PhCN. Complex 11 was derived from [Li(LL')]2 and [NiBr(2)(dme)]. The solution obtained from 1 + 2 PhCN in Et2O at ambient temperature was a mixture (5) of 3 (predominantly) and 7. The 1-azaallyl complex 8 has the ligand bound to the metal as the enamide, and this is also probably (NMR) the case for 6. The molecular structures of the crystalline complexes 7, 8 and 11 are presented; that of 10 was published earlier. Compound 7, a cyclooctamer, is particularly interesting, in that each LL'- ligand is bridging via one of its N atoms to two neighbouring sodium ions and is not only N,N'- but also (eta2-C[=]C)-chelating to one of them.     

Reactions between a sodium amide Na[N(SiMe3)R1] (R1 = SiMe3, SiMe2Ph or But) and a cyanoalkane RCN (R = Ad or Bu(t))

Reactions between sodium amides Na[N(SiMe3)R1] [R1 = SiMe3 (1), SiMe2Ph (2) or But (3)] and cyanoalkanes RCN (R = Ad or But) were investigated. In each case the nitrile adduct [Na{mu-N(SiMe3)2}(NCR)]2 [R = Ad (1a) or But (1b)], trans-[Na{mu-N(SiMe3)(SiMe2Ph)}(NCR)]2 [R = Ad (2a) or But (2b)], [(Na{mu-N(SiMe3)But})3(NCAd)3] (3a) or [(Na{mu-N(SiMe3)But})3(NCBut)n] [n = 3 (3b) or 2 (3c)] was isolated. The reaction of complexes 3a or 3b with benzene afforded the ketimido complex [Na{mu-N=C(Ad)(Ph)}]6.2C6H6 (4a) or [Na{mu-N=C(But)(Ph)}]6 (4b); the former was also prepared in more conventional fashion from NaPh and AdCN. The synthesis and structure of an analogue of complex 1a, [Li{mu-N(SiMe3)2}(NCAd)]2 (5a), is also presented. The compounds 1a, 1b, 2a, 2b, 3, 3b, 4a, 4b and 5a were characterised by X-ray diffraction.     

Iridium(III) silyl alkyl and iridacyclic compounds supported by 4,4'-di-tert-butyl-2,2'-bipyridyl

Treatment of IrCl(3)x H(2)O with one equivalent of 4,4'-di-tert-butyl-2,2'-bipyridyl (dtbpy) in N,N-dimethylformamide (dmf) afforded [IrCl(3)(dmf)(dtbpy)] (1). Alkylation of 1 with Me(3)SiCH(2)MgCl resulted in C--Si cleavage of the Me(3)SiCH(2) group and formation of the Ir(III) silyl dialkyl compound [Ir(CH(2)SiMe(3))(dtbpy)(Me)(SiMe(3))] (2), which reacted with tBuNC to afford [Ir(tBuNC)(CH(2)SiMe(3))(dtbpy)(Me)(SiMe(3))] ([2(tBuNC)]). Reaction of 2 with phenylacetylene afforded dimeric [{Ir(C[triple chemical bond]CPh)(dtbpy)(SiMe(3))}(2)(mu-C[triple chemical bond]CPh)(2)] (3), in which the bridging PhC[triple chemical bond]C(-) ligands are bound to Ir in a mu-sigma:pi fashion. Alkylation of 1 with PhMe(2)CCH(2)MgCl afforded the cyclometalated compound [Ir(dtbpy)(CH(2)CMe(2)C(6)H(4))(2-C(6)H(4)CMe(3))] (4), which features an agostic interaction between the Ir center and the 2-tert-butylphenyl ligand. The cyclic voltammogram of 4 in CH(2)Cl(2) shows a reversible Ir(IV)-Ir(III) couple at about 0.02 V versus ferrocenium/ferrocene. Oxidation of 4 in CH(2)Cl(2) with silver triflate afforded an Ir(IV) species that exhibits an anisotropic electron paramagnetic resonance (EPR) signal in CH(2)Cl(2) glass at 4 K with g( parallel)=2.430 and g( perpendicular)=2.110. Protonation of 4 with HCl and p-toluenesulfonic acid (HOTs) afforded [{Ir(dtbpy)(CH(2)CMe(2)Ph)Cl}(2)(mu-Cl)(2)] (5) and [Ir(dtbpy)(CH(2)CMe(2)Ph)(OTs)(2)] (6), respectively. Reaction of 5 with Li[BEt(3)H] gave the cyclometalated complex [{Ir(dtbpy)(CH(2)CMe(2)C(6)H(4))}(2)(mu-Cl)(2)] (7). Reaction of 4 with tetracyanoethylene in refluxing toluene resulted in electrophilic substitution of the iridacycle by C(2)(CN)(3) with formation of [Ir(dtbpy)(CH(2)CMe(2)C(6)H(3){4-C(2)(CN)(3)})(2-C(6)H(4)CMe(3))] (8). Reaction of 4 with diethyl maleate in refluxing toluene gave the iridafuran compound [Ir(dtbpy)(CH(2)CMe(2)C(6)H(4)){kappa(2)(C,O)-C(CO(2)Et)CH(CO(2)Et)}] (9). Treatment of 9 with 2,6-dimethylphenyl isocyanide (xylNC) led to cleavage of the iridafuran ring and formation of [Ir(dtbpy)(CH(2)CMe(2)C(6)H(4)){C(CO(2)Et)CH(CO(2)Et)}(xylNC)] (10). Protonation of 9 with HBF(4) afforded the dinuclear neophyl complex [(Ir(dtbpy)(CH(2)CMe(2)Ph){kappa(2)(C,O)-C(CO(2)Et)CH(CO(2)Et)})(2)][BF(4)](2) (11). The solid-state structures of complexes 2-5 and 8-11 have been determined.     

Magnesium(II) complexes of 2,4-N,N'-disubstituted 1,3,5-triazapentadienyl ligands: synthesis and characterization of [N(Dipp)C(NMe2)NC(NMe(2))N(SiMe3)MgBr]2 and [N(R)C(R')NC(R')N(SiMe3)]2Mg (Dipp = 2,6-iPr2-C6H3, R = Ph, SiMe(3); R' = NMe2, 1-piperidino)

Treatment of the appropriate lithium or sodium 2,4-N,N'-disubstituted 1,3,5-triazapentadienate [RNC(R')NC(R')N(SiMe(3))M](2) (R = Ph, 2,6-(i)Pr(2)-C(6)H(3)(Dipp) or SiMe(3); R' = NMe(2) or 1-piperidino; M = Li or Na) with one or half equivalent portion of MgBr(2)(THF)(2) in Et(2)O under mild conditions furnishes in good yield the first structurally characterized molecular magnesium 2,4-N,N'-disubstituted 1,3,5-triazapentadienates [DippNC(NMe(2))NC(NMe(2))N(SiMe(3))MgBr](2) (1), [{RNC(R')NC(R')N(SiMe(3))}(2)Mg] (R = Ph, R' = NMe(2) 2; R = Ph, R' = 1-piperidino 3; R = SiMe(3), R' = 1-piperidino 4). The solid-state structure of 1 is dimeric and those of 2, 3, and 4 are monomeric. The ligand backbone NCNCN in 1 adopts a W-shaped configuration, while in 2, 3 and 4 adopts a U-shaped configuration.     

Towards carbohydrate derivatives of the ReI(CO)3 fragment

With the [Re(CO)(3)Br(3)](2-) ion as a precursor for the Re(I)(CO)(3) fragment, the diols (1R,2R)-cyclohexane-1,2-diol [(1R,2R)-Chxd], anhydroerythritol (AnEryt), and (1S,2S)-cyclopentane-1,2-diol [(1S,2S)-Cptd] form dinuclear monoanions in the salts (NBu(4))[(Re(2)(CO)(6){mu-(1R,2R)-ChxdH(-1)}(3)] (1), [K([18]crown-6)][Re(2)(CO)(6)(mu-OMe)(2)(mu-AnErytH(-1))] (2) and (NBu(4))[Re(2)(CO)(6){mu-(1S,2S)-CptdH(-1)}(3)] (3). The monoanionic diolato ligands in these triply bridged dirhenates(I) are monodentate. Bridging triolato ligation in the trirhenates(I) is supported by the anions of glycerol (Glyc) and methyl beta-D-ribopyranoside (Me-beta-D-Ribp), the latter binding in its (1)C(4) conformation, in (DBUH)(2)[Re(3)(CO)(9)(mu(3)-O)(mu(3)-GlycH(-3))]0.5 MeCN (4 a), (NEt(4))[Re(3)(CO)(9)(mu(3)-OMe)(mu(3)-GlycH(-3))] (4 b) and (DBUH)[Re(3)(CO)(9)(mu(3)-OMe)(mu(3)-(1)C(4)-Me-beta-D-Ribp2,3,4H(-3))] (5). The chiral sugar alcohols L-threitol (L-Thre) and D-arabitol (D-Arab) act as tetra- and pentadentate ligands, respectively, in (NEt(4))[Re(2)(CO)(6)(L-ThreH(-3))]MeCN (6) and (NEt(4))(2)(DBUH)(2)[Re(6)(CO)(18)(D-ArabH(-5))(2)] (7). Complexes 6 and 7 are free of supporting oxo or methoxo ligands and use solely the O-atom pattern of the polyol for the connection of the Re(I)(CO)(3) moieties.     

Synthesis and structures of selected triazapentadienate of Li, Mn, Fe, Co, Ni, Cu(I), and Cu(II) using 2,4-N,N'-disubstituted 1,3,5-triazapentadienate anions as ancillary ligands: [N(Ar)C(NMe2)NC(NMe2)N(R)](-) (Ar = Ph, 2,6-(i)Pr2-C6H3; R = H, SiMe3)

Addition reaction of ArN(SiMe 3)M (Ar = Ph or 2,6 - (i) Pr 2-C 6H 3 (Dipp); M = Li or Na) to 2 equivalents of alpha-hydrogen-free nitrile RCN (R = dimethylamido) gave the dimeric [M{N(Ar)C(NMe 2)NC(NMe 2)N(SiMe 3)}] 2 ( 1a, Ar = Ph, M = Li; 1b, Ar = Ph, M = Na; 1c, Ar = Dipp, M = Li). 1d was obtained by hydrolysis of 1c at ambient temperature. Treatment of a double ratio of 1a or 1b with anhydrous MCl 2 (M = Mn, Fe, Co) yielded the 1,3,5-triazapentadienato complexes [M{N(Ph)C(NMe 2)NC(NMe 2)N(SiMe 3)} 2] (M = Mn, 2; Fe, 3; Co, 4) and with NiCl 2.6H 2O gave [M{N(Ph)C(NMe 2)NC(NMe 2)N(H)} 2] (M = Ni, 5). Treatment of an equiv of 1c with anhydrous CuCl in situ and in air led to complexes [{N(Dipp)C(NMe 2)NC(NMe 2)N(SiMe 3)}CuPPh 3] 6 and [Cu{N(Dipp)C(NMe 2)NC(NMe 2)N(H)} 2] 7, respectively. 1c, 1d, and 2- 7 were characterized by X-ray crystallography and microanalysis. 1c, 1d, 5, and 6 were well characterized by (1)H, (13)C NMR, 1c by (7)Li, and 6 by (31)P NMR as well. The structural features of these complexes were described in detail.     

Iodide, azide, and cyanide complexes of (N,C), (N,N), and (N,O) metallacycles of tetra- and pentavalent uranium

In contrast to the neutral macrocycle [UN*(2)(N,C)] (1) [N* = N(SiMe(3))(3); N,C = CH(2)SiMe(2)N(SiMe(3))] which was quite inert toward I(2), the anionic bismetallacycle [NaUN*(N,C)(2)] (2) was readily transformed into the enlarged monometallacycle [UN*(N,N)I] (4) [N,N = (Me(3)Si)NSiMe(2)CH(2)CH(2)SiMe(2)N(SiMe(3))] resulting from C-C coupling of the two CH(2) groups, and [NaUN*(N,O)(2)] (3) [N,O = OC(═CH(2))SiMe(2)N(SiMe(3))], which is devoid of any U-C bond, was oxidized into the U(V) bismetallacycle [Na{UN*(N,O)(2)}(2)(μ-I)] (5). Sodium amalgam reduction of 4 gave the U(III) compound [UN*(N,N)] (6). Addition of MN(3) or MCN to the (N,C), (N,N), and (N,O) metallacycles 1, 4, and 5 led to the formation of the anionic azide or cyanide derivatives M[UN*(2)(N,C)(N(3))] [M = Na, 7a or Na(15-crown-5), 7b], M[UN*(2)(N,C)(CN)] [M = NEt(4), 8a or Na(15-crown-5), 8b or K(18-crown-6), 8c], M[UN*(N,N)(N(3))(2)] [M = Na, 9a or Na(THF)(4), 9b], [NEt(4)][UN*(N,N)(CN)(2)] (10), M[UN*(N,O)(2)(N(3))] [M = Na, 11a or Na(15-crown-5), 11b], M[UN*(N,O)(2)(CN)] [M = NEt(4), 12a or Na(15-crown-5), 12b]. In the presence of excess iodine in THF, the cyanide 12a was converted back into the iodide 5, while the azide 11a was transformed into the neutral U(V) complex [U(N{SiMe(3)}SiMe(2)C{CHI}O)(2)I(THF)] (13). The X-ray crystal structures of 4, 7b, 8a-c, 9b, 10, 12b, and 13 were determined.     

Synthesis, structural characterization, reactivity, and thermal stability of [eta(5):sigma-Me2C(C5H4)(C2B10H10)]Ti(R)(NMe2)

Reaction of [eta:(5)sigma-Me2C(C5H4)(C2B10H10)]TiCl(NMe2) (1) with 1 equiv of PhCH2K, MeMgBr, or Me3SiCH2Li gave corresponding organotitanium alkyl complexes [eta:(5)sigma-Me2C(C5H4)(C2B10H10)]Ti(R)(NMe2) (R = CH2Ph (2), CH2SiMe3 (4), or Me (5)) in good yields. Treatment of 1 with 1 equiv of n-BuLi afforded the decomposition product {[eta:(5)sigma-Me2C(C5H4)(C2B10H10)]Ti}2(mu-NMe)(mu:sigma-CH2NMe) (3). Complex 5 slowly decomposed to generate a mixed-valence dinuclear species {[eta:(5)sigma-Me2C(C5H4)(C2B10H10)]Ti}2(mu-NMe2)(mu:sigma-CH2NMe) (6). Complex 1 reacted with 1 equiv of PhNCO or 2,6-Me2C6H3NC to afford the corresponding monoinsertion product [eta:(5)sigma-Me2C(C5H4)(C2B10H10)]Ti(Cl)[eta(2)-OC(NMe2)NPh] (7) or [eta:(5)sigma-Me2C(C5H4)(C2B10H10)]Ti(Cl)[eta(2)-C(NMe2)=N(2,6-Me2C6H3)] (8). Reaction of 4 or 5 with 1 equiv of R'NC gave the titanium eta(2)-iminoacyl complexes [eta:(5)sigma-Me2C(C5H4)(C2B10H10)]Ti(NMe2)[eta(2)-C(R)=N(R')] (R = CH2SiMe3, R' = 2,6-Me2C6H3 (9) or tBu (10); R = Me, R' = 2,6-Me2C6H3 (11) or tBu (12)). The results indicated that the unsaturated molecules inserted into the Ti-N bond only in the absence of the Ti-C(alkyl) bond and that the Ti-C(cage) bond remained intact. All complexes were fully characterized by various spectroscopic techniques and elemental analyses. Molecular structures of 2, 3, 6-8, and 10-12 were further confirmed by single-crystal X-ray analyses.     

Structural diversity in solvated lithium aryloxides. Syntheses, characterization, and structures of [Li(OAr)(THF)x]n and [Li(OAr)(py)x]2 complexes where OAr = OC6H5, OC6H4(2-Me), OC6H3(2,6-(Me))2, OC6H4(2-Pr(i)), OC6H3(2,6-Pr(i)))2, OC6h4(2-Bu(t)), OC6H3(2,6-Bu(t)))2

A series of sterically varied aryl alcohols H-OAr [OAr = OC6H5 (OPh), OC6H4(2-Me) (oMP), OC6H3(2,6-(Me))2 (DMP), OC6H4(2-Pr(i)) (oPP), OC6H3(2,6-(Pr(i)))2 (DIP), OC6H4(2-Bu(t)) (oBP), OC6H3(2,6-(Bu(t)))2 (DBP); Me = CH3, Pr(i) = CHMe2, and Bu(t) = CMe3] were reacted with LiN(SiMe3)2 in a Lewis basic solvent [tetrahydrofuran (THF) or pyridine (py)] to generate the appropriate "Li(OAr)(solv)x". In the presence of THF, the OPh derivative was previously identified as the hexagonal prismatic complex [Li(OPh)(THF)]6; however, the structure isolated from the above route proved to be the tetranuclear species [Li(OPh)(THF)]4 (1). The other "Li(OAr)(THF)x" products isolated were characterized by single-crystal X-ray diffraction as [Li(OAr)(THF)]4 [OAr = oMP (2), DMP (3), oPP (4)], [Li(DIP)(THF)]3 (5), [Li(oBP)(THF)2]2, (6), and [Li(DBP)(THF)]2, (7). The tetranuclear species (1-4) consist of symmetric cubes of alternating tetrahedral Li and pyramidal O atoms, with terminal THF solvent molecules bound to each metal center. The trinuclear species 5 consists of a six-membered ring of alternating trigonal planar Li and bridging O atoms, with one THF solvent molecule bound to each metal center. Compound 6 possesses two Li atoms that adopt tetrahedral geometries involving two bridging oBP and two terminal THF ligands. The structure of 7 was identical to the previously reported [Li(DBP)(THF)]2 species, but different unit cell parameters were observed. Compound 7 varies from 6 in that only one solvent molecule is bound to each Li metal center of 7 because of the steric bulk of the DBP ligand. In contrast to the structurally diverse THF adducts, when py was used as the solvent, the appropriate "Li(OAr)(py)x" complexes were isolated as [Li(OAr)(py)2]2 (OAr = OPh (8), oMP (9), DMP (10), oPP (11), DIP (12), oBP (13)) and [Li(DBP)(py)]2 (14). Compounds 8-13 adopt a dinuclear, edge-shared tetrahedral complex. For 14, because of the steric crowding of the DBP ligand, only one py is coordinated, yielding a dinuclear fused trigonal planar arrangement. Two additional structure types were also characterized for the DIP ligand: [Li(DIP)(H-DIP)(py)]2 (12b) and [Li2(DIP)2(py)3] (12c). Multinuclear (6,7Li and 13C) solid-state MAS NMR spectroscopic studies indicate that the bulk powder possesses several Li environments for "transitional ligands" of the THF complexes; however, the py adducts possess only one Li environment, which is consistent with the solid-state structures. Solution NMR studies indicate that "transitional" compounds of the THF precursors display multiple species in solution whereas the py adducts display only one lithium environment.