Reaction of E t,A s with AsCl, in n-pentane yields dimeric [Et,A sX AsC13]2 in quantitative yield; sublimation in vacuo affords white crystals. X-Ray diffraction data were collected at 133 K (3149 independent observed reflections; R = 0.029. Rw = 0.026). Crystal data: monoclinic space group P2,/c, a = 761.9(8). b = 1118.8(4). c = 1406.0(14) pm; ß = 100.90(4)°. Z = 2 dimers. The dimer contains a planar A s2Cl6-unit with terminal and bridging As —Cl bonds; each arsenic atom is bonded to a Et3As molecule via an arsenic—arsenic bond. The dimer thus has pseudo fourand six-coordinate arsenic atoms.

In contrast to tBu(2)SiN(Li)SiXtBu(2) (X = Cl, tBu), the silyl amide Me2SiCIN(Li)SitBu(3) is unstable towards LiCl elimination, which means that the silanimine donor adduct Me2Si=NSitBu(3)center dot NMe2Et can be synthesized in high yield from the reaction of Me2SiCIN(H)SitBu(3) with nBuLi in the presence of NMe2Et. The silanimine adduct tBu(2)Si=NSiCltBu(2)center dot NMe2Et, with bulky tBu substituents at the unsaturated Si center, is accessible by treating the donor-free silanimine tBu(2)Si=NSiCltBu(2) with NMe2Et. X-ray quality crystals of the silanimine amine adduct Me2Si=NSitBu(3)-NMe2Et (monoclinic, P2(1)/n) were grown from pentane at -25 degrees C. During thermolysis of the adducts Me2Si=NSitBu(3)center dot NMe2Et and tBu(2)Si=NSiCltBu(2)-NMe2Et in NMe2Et as solvent a Stevens rearrangement takes place to produce EtN(Me)CH2SiMe2N(H)SitBu(3) and EtN(Me)CH[Me2SiN(H)SitBu(3)](2), and EtN(Me)CH(2)SitBu(2)N(H)SiCltBu(2), respectively. In contrast, the thermolysis of Me2Si=NSitBu(3)center dot NMe2Et in vacuo gives the silanimine dimer (Me(2)SiNSitBu(3))2 (monoclinic, P2(1)/n) in 80% yield. The benzophenone imine Ph2C=NSitBu(3) (triclinic, P (1) over bar) was obtained from the Wittig-like reaction of Me2Si=N-SitBu(3) with Ph2CO. (c) Wiley-VCH Verlag GmbH & Co.

A new route to the synthesis of 1,4,7-tris(2-aminoethyl)-1,4,7-triazacyclononane has been introduced. This polyamino derivative of 1,4,7-triazacyclononane has been used to synthesise a new ligand (L) by Schiff-base condensation with sodium pyruvate in the presence of lanthanide(III) (Ln) ions as templating agents to form the complexes [Ln(L)] (Ln=Y, La, Sm, Yb). The ligand L has nine donor atoms comprising three amine and three imine N-donors and three carboxylate O-donors, and forms thermodynamically and kinetically stable Ln(III) complexes in which the three pendant arms of the ligand wrap around the nine-co-ordinate Ln(III) centres. Complexes with La(III), Sm(III) and Y(III) have been structurally characterised. All the complexes are isostructural and the co-ordination polyhedron about the lanthanide centre is in each case slightly distorted tricapped trigonal prismatic, with the two triangular faces of the prism formed by the macrocyclic N-donors and the carboxylate O-donors. NMR spectroscopic studies on the diamagnetic Y(III) and La(III) complexes and on the paramagnetic Yb(III) and Sm(III) complexes indicate that L imposes a very rigid co-ordination cage around the metal centre.

Molecules of the title compound, [Cu(C 2 H 3 N)(C 11 H 9 N 5 )(C 6 H 6 N 2 O)](BF 4 ) 2 ·2C 2 H 3 N, comprise (aceto­nitrile)[2,6-bis(pyrazol-1-yl)­pyridine](isonicotin­amide)copper(II) cations, tetra­fluoro­borate anions and lattice aceto­nitrile mol­ecules. The cations have distorted square-pyramidal geometries in which the N 3 -donor, viz . 2,6-bis­(pyrazol-1-yl)­pyridine, and the N-donor, viz . the isonicotin­amide ligand, occupy the four basal positions, with the coordinated aceto­nitrile N-donor atom occupying the apical position. Pairs of cations are linked by N—H⋯F hydrogen bonds through tetra­fluoro­borate anions, forming centrosymmetric dimers, which are further linked by C—H⋯O hydrogen bonds into two-dimensional undulating sheets, three of which interpenetrate to generate a two-dimensional network.

Molecules of the title compound, [Cu(C(2)H(3)N)(C(11)H(9)N(5))(C(6)H(6)N(2)O)](BF(4))(2).2C(2)H(3)N, comprise (acetonitrile)[2,6-bis(pyrazol-1-yl)pyridine](isonicotinamide)copper(II) cations, tetrafluoroborate anions and lattice acetonitrile molecules. The cations have distorted square-pyramidal geometries in which the N(3)-donor, viz. 2,6-bis(pyrazol-1-yl)pyridine, and the N-donor, viz. the isonicotinamide ligand, occupy the four basal positions, with the coordinated acetonitrile N-donor atom occupying the apical position. Pairs of cations are linked by N-H.F hydrogen bonds through tetrafluoroborate anions, forming centrosymmetric dimers, which are further linked by C-H.O hydrogen bonds into two-dimensional undulating sheets, three of which interpenetrate to generate a two-dimensional network.

The preprogrammed achiral oligomers (3) and (4), composed of pyridine-pyrimidine sequences containing up to 27 heterocycles, undergo self-organization into extended multiturn helical structures both in solution and in the solid state, with spontaneous chiral resolution of 3 on crystallization.

NaPPh2, prepared from sodium and PClPh2 in refluxing dioxane, crystallises from dioxane as [Na4(μ-dioxane)8/2(μ-dioxane)(PPh2)4]∞ (1), in which the basic structural features are eight-membered Na4P4 rings, linked by intermolecularly bridging dioxane molecules to give a three-dimensional network, and inclusion of one dioxane molecule inside the eight-membered ring. 1 crystallises in the orthorhombic space group Cmc21 (no. 36), T = 203(2) K, a = 27.377(1) Å, b = 10.579(1) Å, c = 23.608(1) Å, V = 6837.3(6) Å3, Z = 4, and the absolute structure parameter 0.3(2). The refinement converged to R1 = 0.0632, wR2 = 0.1701 (for reflections with I > 2σ(I)), R1 = 0.0707, wR2 = 0.1781 (all data).

Coordination of the pentatopic ligand 3 with Ag-I leads to the simultaneous self-assembly of two polynuclear architectures: a [4 x 5] grid-type species 10 and a quadruple-helicate 11, which contain twenty and ten silver ions, respectively. Their structures have been established by X-ray diffraction analysis of the crystals obtained as a mixture on crystallisation. Complex 10 contains two [2 x 5]-Ag-10(I) rectangular subgrids located on opposite sides of an array of parallel ligands of 3 that are twisted into a transoid N=C-C=N arrangement around the central C-C bond; it may thus be formulated as a grid of grids: [2 x (2 x 5)]. Complex 11 is an inorganic quadruple helicate that consists of two sets of two parallel ligands of 3 connected by an array of ten silver ions. Both compounds 10 and 11 are novel types of polynuclear complexes that are composed of two subunits. Their formation points to the possibility of generating specific arrays of metal ions by self-assembly, involving, in particular, a combination of subunits within the overall entity. They represent organised patterns of ion dots of special significance in view of their formal relationship to quantum dots.

The reaction of [LWCl] (3) [L = N(CH2CH2NiPr)3] with LiE(SiMe3)2 (E = P, As, Sb) yields the novel, neutral pnictido-bridged complexes [LW = E = WL] (5-7). By following the reaction, which starts from the LiP-(SiMe3)2 derivative, by 31P NMR spectroscopy, the formation of an intermediate with a terminal pnictido ligand can be ruled out. The paramagnetic complexes 5-7 are comprehensively spectroscopically characterised. The X-ray structure analysis of the heterocumulenes 5-7 reveals a linear structure in which the two W-"tren" units bind to the central pnictido atom in a staggered conformation ["tren" = tren-based ligand; tren = tris(2-aminoethyl)-amine. When N2 is used as the inert gas in the synthesis of the starting material [N(CH2CH2NNp)3WCl] [Np = CH2C-(CH3)3], the complex [[N(CH2CH2NNp)3]W2(mu, eta 1: eta 1-N2)] (4) is formed as a side product. Complex 4 possesses a hydrazido(4-) (N2(4-)) ligand connected by two tungsten-"tren" moieties.

The influence of anions and intermolecular aromatic interactions on the orientation of one dimensional silver(I) co-ordination polymers has been studied. Reaction of AgX with 2,7-diazapyrene (diaz) (X=BF4- or NO3-), 1,4-bis(4-pyridyl)butadiyne (pybut) (X=BF4-, NO3-, PF6- or MeCO2-), 4,4'-bipy (X=BF4-) or 1,4-bis(4-pyridylethynyl)phenylene (pyphe) (X=PF6-) afforded products of general formula {[Ag(ligand)]X}(infinity). All of the products have been structurally characterised by single crystal X-ray diffraction confirming that they exist as one-dimensional linear chain co-ordination polymers. The arrangement of the chains with respect to each other in the solid state is discussed and evaluated in terms of the relative co-ordinating ability of the anion used and the tendency of the N-donor ligand to adopt intermolecular aromatic interactions. For the complexes of diaz the overriding force in controlling chain orientation was shown to be pi-pi interactions between diaz ligands on adjacent chains. In the case of the pybut complexes the most dominant forces were shown to be metal-anion interactions with aromatic pi-pi interactions and Ag . . . Ag interactions playing a less influential role. In the case of {[Ag(pyphe)]PF6}(infinity) Ag . . . aromatic interactions are important in the overall arrangement of adjacent chains.

The synthesis and X-ray structures of three metal complexes with terpyridine-derived ligands that contain amino-pyrimidine and amino-pyrazine moieties are presented. They have been designed in view of directing their self-assembly into specific supramolecular arrays through molecular recognition interactions. The solid-state structures indeed reveal extensive hydrogen-bonded networks. The Co complex 4a with PF6- counterions builds a two-dimensional infinite interwoven grid through strong double hydrogen bonds (d(N-H-N) =2.918-3.018 A) between the amino groups and the N atoms of the rings, with all H-bonding sites saturated. Changing the anions to BF4- in 4b leads to a similar infinite but partially broken grid with a quarter of the H-bonding sites unsaturated (d(N-H-N)=2.984-3.206 A). In the case of the Zn complex 12 with triflate anions, half of the hydrogen bonds are formed. Only one of the two orthogonal ligands has hydrogen bonds (d(N-H-N) = 3.082, 3.096 A) to the neighbouring complexes and thus builds linear, supramolecular, polymeric chains. These structural differences are mainly attributed to crystal-packing effects caused by the different anions. The data presented here may also be regarded as a prototype for the generation of organised arrays through sequential self-assembly processes.

NaPPh2, prepared from sodium and PClPh2 in refluxing dioxane, crystallises from dioxane as [Na-4(mu-dioxane)(8/2)(mu-dioxane)(PPh2)(4)](infinity) (1), in which the basic structural features are eight-membered Na4P4 rings, linked by intermolecularly bridging dioxane molecules to give a three-dimensional network, and inclusion of one dioxane molecule inside the eight-membered ring. 1 crystallises in the orthorhombic space group Cmc2(1) (no.36), T = 203(2) K, a = 27.377(1) Angstrom, b = 10.579(1) Angstrom, c = 23.608(1) Angstrom, V = 6837.3(6) Angstrom(3), Z = 4, and the absolute structure parameter 0.3(2). The refinement converged to R1 = 0.0632, wR2 = 0.1701 (for reflections with I > 2 sigma(I)), R1 = 0.0707, wR2 = 0.1781 (all data).

The reaction of SbCl3 with various transition metal metalates of the type K[MLn] [MLn = Ni(CO)Cp*, Fe(CO)Cp', Co(CO)(4); Cp* = eta(5)-C5Me5, Cp' = eta(5)-C5H4Me] in the presence of [Cr(CO)(5)thf] have been studied. With K[Ni(co)Cp*] and K[Fe(CO)(2)Cp'] the trigonal-pyramidal complexes [(mu(3)-Sb){Ni(CO)Cp*}(3)] (1) and [mu(3)-Sb){Fe . (CO)(2)Cp'}(3)] (2), respectively, are obtained. The reaction with K[Co(CO)(4)] leads to the tetrahedral cluster [Co-3(CO)(9)(mu(3)- Sb{Cr(CO)(5)})] (3) and the butterfly cluster [Co-2(CO)(6)(mu-SbCl)(mu-sbCl{(Cr(CO)(5)})] (4). All products are characterised by X-ray crystal structure determination. In contrast to the corresponding [(CO)(5)CrPCl3] system forming P-P bonds, starting from SbC4/[Cr(CO)(5)thf] does not cause a Sb-Sb bond formation.

Das Reaktionsverhalten von SbCl3 gegenüber verschiedenen Übergangsmetallcarbonylmetallaten des Typs K[MLn] [MLn = Ni(CO)Cp*, Fe(CO)Cp′, Co(CO)4; Cp* = η5-C5Me5, Cp′ = η5-C5H4Me] in Gegenwart von [Cr(CO)5thf] wurde untersucht. Mit K[Ni(CO)Cp*] bzw. K[Fe(CO)2Cp′] werden die trigonal-pyramidalen Komplexe [(μ3-Sb){Ni(CO)Cp*}3] (1) bzw. [(μ3-Sb){Fe(CO)2Cp′}3] (2) isoliert. Die Reaktion mit K[Co(CO)4] liefert den tetraedrisch strukturierten Cluster [Co3(CO)9〈μ3-Sb{Cr(CO)5}〉] (3) sowie den Schmetterlings-Cluster [Co2(CO)6(μ-SbCl) · (μ-SbCl{Cr(CO)5})] (4). Alle Produkte werden durch Kristallstrukturanalysen charakterisiert. Im Unterschied zu der Bildung von P–P-Bindungen ausgehend von [(CO)5CrPCl3] bewirkt bei den untersuchten Umsetzungen ausgehend von SbCl3 die Gegenwart von [Cr(CO)5thf] keine Sb–Sb-Bindungsknüpfung. Investigations of Sb–Sb Bond Formation Reactions in the Coordination Sphere of Transition Metals The reaction of SbCl3 with various transition metal metalates of the type K[MLn] [MLn = Ni(CO)Cp*, Fe(CO)Cp′, Co(CO)4; Cp* = η5-C5Me5, Cp′ = η5-C5H4Me] in the presence of [Cr(CO)5thf] have been studied. With K[Ni(CO)Cp*] and K[Fe(CO)2Cp′] the trigonal-pyramidal complexes [(μ3-Sb){Ni(CO)Cp*}3] (1) and [(μ3-Sb){Fe · (CO)2Cp′}3] (2), respectively, are obtained. The reaction with K[Co(CO)4] leads to the tetrahedral cluster [Co3(CO)9(μ3-Sb{Cr(CO)5})] (3) and the butterfly cluster [Co2(CO)6(μ-SbCl)(μ-SbCl{Cr(CO)5})] (4). All products are characterised by X-ray crystal structure determination. In contrast to the corresponding [(CO)5CrPCl3] system forming P–P bonds, starting from SbCl3/[Cr(CO)5thf] does not cause a Sb–Sb bond formation.

Two enantiomeric pairs of chiral terpy ligands (I and II; III and IV) bearing enantiopure bornyloxy substituents at the 6-position were prepared in high yield, stereoretentive reactions from (1R)-endo- or (1S)-endo- borneol; compounds I, II and III were structurally characterised. Dinuclear double helicates were formed upon reaction with copper(I) salts, but solvent-dependent and reversible formation of mononuclear or dinuclear double-helical complexes was observed with silver(I) salts. The double helicates are formed with good to excellent diastereoselectivity for helical chirality. With these 6-substituted ligands, double helicates can exist as head-to-head (HH) or head-to-tail (HT) isomers; in solution, the HT isomers are favored, although solid state interactions can overcome this preference.

Ligand 3 has been shown to self-assemble under coordination of copper(II) cations in a 1:1 ratio in acetonitrile to give equilibrating mixtures of a [2 x 2] grid-type tetranuclear structure 1 and a hexanuclear achitecture of hexagonal shape 2. The latter was confirmed by determination of the crystal structure which further indicated that 2 contained acetonitrile molecules and hydroxo groups bound to the copper(II) centers, which are therefore five-coordinate. The structures assigned to 1 and 2 were further supported by the spectral (mass, UV/Vis) data. The self-assembly process is strongly dependent on the conditions of the medium. An increase in concentration in acetronitrile increases the relative amount of hexamer 2, which appears to be the favored entity at the highest concentrations that can be reached before precipitation occurs. On the other hand, in nitromethane only the tetranuclear complex 1 was detected by mass spectrometry. Replacement of nitromethane by acetonitrile and vice versa indicated the reversible switching between a solution containing either 1 alone or an equilibrium mixture of 1 and 2, respectively. In conclusion, the system described presents several remarkable features: 1) self-assembly with substrate binding, 2) dynamic combinatorial structure generation, and 3) environment-induced structural switching amounting in effect to a process of adaptive self-assembly.

The polytopic linear 4 and circular 5 ligands undergo self-assembly with copper(I) and silver(I) ions to generate the large inorganic entities 2 and 3 containing, two and three internal cavities, respectively. The process amounts to the spontaneous assembly of a total of 15 and 19 particles to yield multicompartmental architectures. The crystal structures of two such complexes have been determined. They confirm the nature of the entities formed and show that in addition several substrate species (anions and solvent molecules) are contained in the cavities. The generation of architectures 2 and 3 presents several important features: it represents a multicomponent mixed-ligand self-assembly process involving self-compartmentalisation with simultaneous inclusion (and selection) of multiple substrate species. Such features are of interest for both the analogies with biological processes and the potential applications in nanoscience. They also amount to a further step in the design of systems of increasing structural and functional complexity.