Isolation of iron(II) aqua and hydroxyl complexes featuring a tripodal H-bond donor and acceptor ligand.

A tripodal ligand platform, tris(5-cycloiminopyrrol-2-ylmethyl)amine (H3[N(pi(Cy))3]), that features a hydrogen bond-accepting secondary coordination sphere when bound anionically to an iron center is reported. Neutral coordination to iron affords ligand tautomerization, resulting in a hydrogen bond-donating secondary coordination sphere, and formation of the tris(5-cyclohexyl-amineazafulvene-2-methyl)amine, H3[N(afa(Cy))3], scaffold. Both binding motifs result in formation of stable, high-spin iron(II) complexes featuring ancillary water, triflate, or hydroxo ligands. Structural analysis reveals that these complexes exhibit distorted trigonal-bipyramidal geometries with coordination of the apical nitrogen to iron as well as three equatorial amine or imine nitrogens, depending on the axial ancillary ligand. Formation of the aqua complex K[(N(pi(Cy))3)Fe(OH2)] (3) illustrated the propensity of the ligand to be hydrogen bond-accepting, whereas the iron triflate species [N(afa(Cy))3Fe](OTf)2 (4) features a hydrogen bond-donating secondary coordination sphere. The ability of each of the three arms of the ligand to tautomerize independently was observed during the formation of the iron-hydroxyl species [N(afa(Cy))2(pi(Cy))]FeOH (5) and characterized by X-ray crystallography and IR spectroscopy. The combined data for the iron complexes established that each arm of the tripodal ligand can tautomerize independently and is likely dependent on the electronic needs of the iron center when binding various substrates.

catena-Poly[[penta-µ-benzoato-µ-chlorido-dioxanedineodymium(III)] dioxane 2.5-solvate].

The asymmetric unit of the title compound, [Nd(2)(C(6)H(5)COO)(5)Cl(C(4)H(8)O(2))]·2.5C(4)H(8)O(2), consists of two Nd(III) ions bridged by one Cl(-) ion, five benzoate ions and one coordinating 1,4-dioxane mol-ecule. One Nd(III) ion is nine-coordinate, with a very distorted monocapped square-anti-prismatic geometry. It is coordinated by two chelating carboxyl-ate groups, three monodentate carboxyl-ate groups, one chloride ion and one dioxane mol-ecule. A second independent Nd(III) ion is eight-coordinated in a distorted square-anti-prismatic geometry by one chelating carboxyl-ate group, five monodentate carboxyl-ate groups and one chloride ion. The chains of the extended structure are parallel to the crystallographic b axis. There is a small amount of void space which is filled with five disordered dioxane solvent mol-ecules per unit cell. The intensity contribution of the disordered solvent molecules was removed by applying the SQUEEZE procedure in PLATON [Spek (2009). Acta Cryst. D65, 148-155].

Effects of the alkali-metal cation size on molecular and extended structures: formation of coordination polymers and hybrid materials in the homologous series [(4-Et-C6H4OM)·(diox)n], M = Li, Na, K, Rb, Cs.

The complete series of group 1 metal 4-ethylphenoxide (4-Et-C(6)H(4)O(-)) networks have been synthesized using 1,4-dioxane (diox) as a neutral linker. [{(4-Et-C(6)H(4)OLi)(4)·(diox)(2.5)}·diox](∞) (1) and [{(4-Et-C(6)H(4)ONa)(6)·(diox)(3)}(∞)] (2) form 2D and 3D networks, respectively, composed of discrete aggregates linked by diox. Compound 1 forms a hexagonal layered structure with Li(4)O(4) cubanes acting as nodes, whereas compound 2 forms a primitive cubic network (pcu) with Na(6)O(6) hexameric nodes. [{(4-Et-C(6)H(4)OK)(3)·diox}(∞)] (3), [{(4-Et-C(6)H(4)ORb)(2)·(diox)(0.5)}(∞)] (4), and [{(4-Et-C(6)H(4)OCs)(2)·(diox)(0.5)}(∞)] (5) are composed of isostructural 1D inorganic rods that are linked through diox to form pcu-type networks. Compound 5 is the first example of a network built from cesium inorganic rods.

1,1,3,3-Tetramethylguanidine solvated lanthanide aryloxides: pre-catalysts for intramolecular hydroalkoxylation.

The synthesis and structural characterization of six 1,1,3,3-tetramethylguanidine (H-TMG) solvated lanthanide aryloxide complexes are reported. Ln[N{Si(CH3)3}2]3 (Ln = Nd, La) was reacted with two equivalents of both H-TMG and HOAr {HOAr = HOC6H2(CMe3)2-2,6 (H-DBP) or HOC6H2(CMe3)2-2,6-CH3-4 (H-4MeDBP)} and one equivelent of ethanol (HOEt) to yield the corresponding [Nd(H-TMG)2(4MeDBP)2(OEt)] (1) and [La(H-TMG)2(DBP)2(OEt)] (2). Compounds 1 and 2 were further reacted with 4-pentyn-1-ol {HO(CH2)3C[triple bond]CH} to isolate [Nd(H-TMG)2(4MeDBP)2{O(CH2)3C[triple bond]CH}] (3) and [La(H-TMG)2(DBP)2{O(CH2)3C[triple bond]CH}] (4), respectively. Three equivalents of HOAr and one equivalent of H-TMG were additionally reacted with Ln[N{Si(CH3)3}2]3 to generate [Nd(4MeDBP)3(H-TMG)] (5) and [La(DBP)3(H-TMG)] (6). In order to examine the formation of 1-6, the interaction of H-TMG and HOAr was further examined in solution and the hydrogen bonded complexes (H-TMG:HOAr), 7 and 8, were isolated. Upon successful isolation of 1-6, the utility of 1, 2, 4 and 5 as pre-catalysts for the intramolecular hydroalkoxylation of 4-pentyn-1-ol was investigated. The bulk powders for all complexes were found to be in agreement with the crystal structures based on elemental analyses, FT-IR spectroscopy, and 1H and 13C NMR investigations.

Synthesis, structure, and reactivity of low-coordinate 1,1,3,3-tetraethylguanidinate complexes.

Diethylcyanamide is added to a hexanes solution of lithium diethylamide [LiN(CH(2)CH(3))(2)] resulting in the formation of lithium 1,1,3,3-tetraethylguanidinate, [Li(mu-TEG)](6) (1). Upon successful isolation of 1, the metathesis reaction of MX(2) (MX(2) = MnBr(2), FeBr(2), CoBr(2), and ZnCl(2)) with [Li(mu-TEG)](6) and lithium bistrimethylsilylamide, LiN(SiMe(3))(2), was performed to generate dinuclear tetraethylguanidinate (TEG) complexes with the general formula [M(mu-TEG){N(SiMe(3))(2)}](2) {M = Mn (2), Fe (3), Co (4), Zn (5)}. Further reaction of 2 with 2 equiv of ethanol (EtOH) and 2 equiv of 2,6-ditert-butylphenol (H-DBP) results in the formation of the manganese alkoxide, [Mn(mu-OEt)(DBP)(H-TEG)](2) (6). Elemental analysis, FT-IR spectroscopy, UV-vis spectroscopy, and single crystal X-ray diffraction were utilized to characterize the six compounds.

Synchrotron study of poly[[di-µ-aqua-(µ-2,2'-bipyridyl-5,5'-dicarboxyl-ato)di-potassium] dihydrate].

The title compound, {[K(2)(C(12)H(6)N(2)O(4))(H(2)O)(2)]·2H(2)O}(n), forms a three-dimensional coordination polymer in the solid state. The asymmetric unit consists of one K(+) ion, half of a 2,2'-bipyridyl-5,5'-dicarboxyl-ate ligand, one coordinated water mol-ecule and one solvent water mol-ecule. The K(+) ion is 7-coordinated by the oxygen atoms of two water mol-ecules and by five oxygen atoms of four carboxyl-ate groups, one of which is chelating. The extended structure can be described as a binodal network in which each K(+) is a six-connected node, bonding to four carboxyl-ate groups and two bridging water mol-ecules, and the 2,2'-bipyridyl-5,5'-dicarboxyl-ate linkers are eight-connected nodes, with each carboxyl-ate group bridging four metal centers. Overall, this arrangement generates a complex network with point symbol {3(4).4(12).5(12)}{3(4).4(4).5(4).6(3)}(2). Both of the bridging water mol-ecules participate as donors in hydrogen-bonding inter-actions; one to solvent water mol-ecules and a second to an oxygen atom of a carboxyl-ate group.

Stable analogs of the uranyl ion containing 1,1,3,3-tetramethylguanidine.

The reaction of 1,1,3,3-tetramethylguanidine (HTMG) with [UO(2)Cl(2)(THF)2] yielded [UO(2)Cl(2)(HTMG)2] 1, the first uranyl tetralkylguanidine adduct reported, further investigation led to the synthesis of [UO(2)(DBP)2(HTMG)2] 2 and [UO(2)(DBP-4-Me)2(HTMG)2] 3 via the reaction of [UO(2){N(SiMe(3))2}2(THF)2] with HTMG and the appropriate aryl alcohol, HO-2,6-(t)Bu(2)-4-RC(6)H(2) (R = H, DBP; R = CH(3), DBP-4-Me).