Biomedical subjects
Publications and source records attributed to Alexander J. Blake.
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New mono- and binuclear titanium imido complexes supported by tetradentate, dianionic N(2)O(2)-donor Schiff base ligands were prepared in good yield from the readily available [Ti(NBu(t))Cl(2)(py)(3)] (1a). Thus treatment of 1a with Na(2)[substituted-salen] gave monomeric [Ti(NBu(t))(substituted-salen)] where substituted-salen = Et(2)salen (2) or Bu(t)(4)salen (4). In contrast, the binuclear complex [Ti(NBu(t)){&mgr;-(MeO)(2)salen}](2) (5) was obtained from 1a and Na(2)[(MeO)(2)salen]. The less sterically crowded compounds 2 and 5 undergo tert-butyl imide/arylamine exchange reactions to form [Ti(N-2,6-C(6)H(3)Me(2))(Et(2)salen)] (3) and [Ti(N-2,6-C(6)H(3)Me(2)){&mgr;-(MeO)(2)salen}](2) (6), respectively, whereas 4 does not exhibit this kind of reactivity. The compound 3 can also be obtained directly from Na(2)[Et(2)salen] and [Ti(N-2,6-C(6)H(3)Me(2))Cl(2)(py)(3)] (1b). Crystal data for 3: triclinic, P&onemacr;, a = 12.216(4) Å, b = 12.312(11) Å, c = 17.246(2) Å, alpha = 90.352(12) degrees, beta = 102.59(2) degrees, gamma = 104.96(2) degrees, V = 2440.3(8) Å(3), Z = 4, R = 0.051, R(w) = 0.066 for 7011 data with I > 2sigma(I). Crystal data for 5.CH(2)()Cl(2)(): orthorhombic, Pbca, a = 14.747(4) Å, b = 17.042(4) Å, c = 20.545(3) Å, V = 5163.5(13) Å(3), Z = 4, R(1) = 0.096, wR(2) = 0.086 for 3765 data with I > 2sigma(I). Crystal data for 6: monoclinic, C2/c, a = 17.902(5) Å, b = 12.411(4) Å, c = 21.068(5) Å, beta = 90.27(2) degrees, V = 4681(2) Å(3), Z = 4, R = 0.034, R(w)() = 0.039 for 3633 data with I > 2sigma(I).
A series of polyether [CH(3)O(CH(2)CH(2)O)(m)()CH(3), with m = 2 (diglyme), 3 (triglyme), 4 (tetraglyme)] mono- or hemiadducts of hexafluoropentanedionatosilver(I) have been synthesized and in selected cases structurally characterized. Decomposition of [Ag(hfa)(diglyme)](2) (hfa = hexafluoropentanedionato) in air affords a mixture of products including crystals of [Ag(2)(hfa)(O(2)CCF(3))(diglyme)(2)]. The structure of [Ag(hfa)(diglyme)](2) consists of two silver cations which are bridged by four oxygens from two hfa ligands; each Ag(I) ion is also coordinated to a chelating diglyme molecule. In comparison, ligation of a longer polyether chain results in a monomeric species [Ag(hfa)(tetraglyme)]. The compounds are soluble in a range of solvents including supercritical carbon dioxide (scCO(2)). Crystal data for [Ag(hfa)(diglyme)](2) (150 K): a = 21.376(3) Å, b = 8.4143(17) Å, c = 21.067(3) Å, beta = 124.05(1) degrees, monoclinic space group C2/c; Z = 8. Crystal data for [Ag(2)(hfa)(O(2)CCF(3))(diglyme)(2)] (150 K): a = 9.0945(12) Å, b = 9.4110(13) Å, c = 17.803(2) Å, alpha = 96.109(14) degrees, beta = 101.649(13) degrees, gamma = 105.06(2) degrees, triclinic space group P&onemacr;; Z = 2. Crystal data for [Ag(hfa)(tetraglyme)] (150 K): a = 14.152(3) Å, b = 16.996(3) Å, c = 8.620(2) Å, beta = 106.99(2) degrees, monoclinic space group P2(1)/c; Z = 4.
Azatriquinane, a tricyclic amine with rigid, hemispherical topology, is synthesized in six steps from pyrrole. This first example of a [2.2.2]cyclazine can be oxidatively dimerized to a novel, highly strained heptacycle or oxidized with chlorine to give an azatriquinacene, a theoretical precursor to diazadodecahedrane via Woodward dimerization.
Reaction of Li[PhC(NSiMe(3))(2)] with the complexes [Ti(NR)Cl(2)(py)(3)] affords the corresponding (N,N'-bis(trimethylsilyl)benzamidinato)titanium imido derivatives [Ti(NR){PhC(NSiMe(3))(2)}Cl(py)(2)] [R = Bu(t) (1), 2,6-C(6)H(3)Me(2) (2), 2,6-C(6)H(3)Pr(i)(2) (3)], which, in solution, exist in temperature-dependent, dynamic equilibrium with their mono(pyridine) homologues [Ti(NR){PhC(NSiMe(3))(2)}Cl(py)] and free pyridine. Kinetic and thermodynamic data for these processes are reported, and the relative contributions of the DeltaH and DeltaS terms associated with all three equilibria are identified. The arylimido complexes 2 and 3 may also be prepared by treating 1 with the appropriate arylamine. Reaction of Li[MeC(NC(6)H(11))(2)] with [Ti(NBu(t))Cl(2)(py)(3)] gives the binuclear N,N'-bis(cyclohexyl)acetamidinato derivative [Ti(2)(&mgr;-NBu(t))(2){MeC(NC(6)H(11))(2)}(2)Cl(2)] (4). The X-ray structures of 2 and 4 have been determined. Crystal data for 2: triclinic, P&onemacr;, a = 11.219(5) Å, b = 12.131(6) Å, c = 13.208(7) Å, alpha = 80.34(5) degrees, beta = 87.41(4) degrees, gamma = 75.13(3) degrees, V = 1722.1(15) Å(3), Z = 2, R = 0.054, R(w) = 0.056. Crystal data for 4: triclinic, P&onemacr;, a = 10.455(3) Å, b = 10.637(5) Å, c = 11.024(3) Å, alpha = 90.52(4) degrees, beta = 112.62(3) degrees, gamma = 114.10(3) degrees, V = 1012.8(10) Å(3), Z = 1, R = 0.0453, R(w) = 0.0495.
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Reaction of 2 equiv of Li[NH-2,6-C(6)H(3)R(2)] with [(Me(4)taa)ZrCl(2)] (Me(4)taaH(2) = tetramethyldibenzotetraaza[14]annulene) gives the bis(amido) derivatives [(Me(4)taa)Zr(NH-2,6-C(6)H(3)R(2))(2)] [R = Pr(i) (1) and Me (2)]. Addition of Me(4)taaH(2) to [Zr(N-2,6-C(6)H(3)Pr(i)(2))(NH-2,6-C(6)H(3)Pr(i)(2))(2)(py)(2)] also affords 1. The reaction of 2 equiv of aryl or alkyl amines H(2)NR with the bis(alkyl) complex [(Me(4)taa)Zr(CH(2)SiMe(3))(2)] is the most versatile method for preparing [(Me(4)taa)Zr(NHR)(2)] (R = 2,6-C(6)H(3)Pr(i)(2), 2,6-C(6)H(3)Me(2), Ph, or Bu(t)). Reaction of 1 equiv of Me(4)taaH(2) with the binuclear complexes [(Bu(t)NH)(2)Zr(&mgr;-NBu(t))(2)Zr(NHBu(t))(2)] or [(py)(HN-2,6-C(6)H(3)Me(2))(2)Zr(&mgr;-N-2,6-C(6)H(3)Me(2))(2)Zr(NH-2,6-C(6)H(3)Me(2))(2)(py)] gives the asymmetrically substituted derivatives [(Me(4)taa)Zr(&mgr;-NR)(2)Zr(NHR)(2)] [R = Bu(t) (6) or 2,6-C(6)H(3)Me(2) (8)], which have been crystallographically characterized.
The reactions of the binuclear oxomolybdenum(V) complex [Cl(2)(O)Mo(&mgr;-OEt)(2)(&mgr;-HOEt)Mo(O)Cl(2)] (1) with Me(3)Si(allyl) and SbF(3) produce the compounds [Mo(6)O(6)Cl(6)(&mgr;(3)-O)(2)(&mgr;(2)-OEt)(6)(&mgr;(2)-Cl)(2)] (2) and [Mo(8)O(8)Cl(6)(&mgr;(3)-O)(4)(OH)(2)(&mgr;(2)-OH)(4)(&mgr;(2)-OEt)(4)(HOEt)(4)] (3), respectively. Treatment of 1 with the Lewis base PMe(3) affords the tetrameric complex [Mo(4)O(4)Cl(4)(&mgr;(2)-OEt)(4)(HOEt)(2)(&mgr;(3)-O)(2)] (4), which represents another link in the chain of clusters produced by the reactions of 1 and simulating the build-up of polymeric molybdenum oxides by sol-gel methods. The crystal structure of 4 has been determined [C(12)H(32)Cl(4)Mo(4)O(12), triclinic, P&onemacr;, a = 7.376(2) Å, b = 8.807(3) Å, c = 11.467(4) Å, alpha = 109.61(1) degrees, beta = 92.12(3) degrees, gamma = 103.75(2) degrees, Z = 1]. By contrast, reaction of 1 with the nitrogen base NEt(3), followed by treatment with [PPN]Cl.2H(2)O ([PPN](+) = [Ph(3)P=N=PPh(3)](+)), gives the complex [PPN](+)[Et(3)NH](+)[Cl(2)(O)Mo(&mgr;(2)-O)(2)Mo(O)Cl(2)](2)(-) (6) in 90% yield. Its crystal structure [C(36)H(30)Cl(4)MoNOP(2), triclinic, Pna2(1), a = 21.470(6) Å, b = 16.765(2) Å, c = 9.6155(14) Å, alpha = 90 degrees, beta = 90 degrees, gamma = 90 degrees, Z = 16] includes the anion [Cl(2)(O)Mo(&mgr;(2)-O)(2)Mo(O)Cl(2)](2)(-), which is a charged derivative of the species forming the gels in sol-gel processes starting from chloromolybdenum ethoxides. Furthermore, compound 1 is found to be catalytically active in esterification and dehydration reactions of alcohols.