The molecular structure of aluminium and iron(III) complexes with 3-phenyl and 3-(4-pyridyl) (HL) substituted acetylacetonate ligands is appreciably distorted. For AlL3 and FeL3 this shows that the orientation of the side pyridyl-N donor atoms lone pairs is about 90 and 135 degrees which favours the assembly of heterobimetallic square patterns in Al(Fe)L3 complexes with metal ions. This was employed for the modular construction of semi-regular heterobimetallic networks, in which the pyridyldiketonate ligands bridge pairs of Fe(Al)/Cd(Co) metal ions and support the structure of 1D and 2D coordination polymers. The unprecedented 2D structure of [Cd[AlL3](CH3OH)[NO3]2].2CHCl3 and Cd[AlL3](CH3OH)Br2].2CHCl3 . 2CH3OH is based upon plane tiling by a set of heterobimetallic squares and octagons, while [Cd[FeL3]2(NO3)2].2H2O and [Co[AlL3]2Cl2].4CHCl3 . 2CH3OH are 1D polymers and exist as chains of heterobimetallic squares sharing opposite vertices.

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A series of framework coordination polymers reveals the use of 1,2,4,5-tetrazines as efficient bridging ligands towards silver(i) and copper(i) ions. All four nitrogen atoms were functional as lone pair donors leading to an unprecedented mu(4)-coordination of the ligands (1,2,4,5-tetrazine, ttz; 3,6-dimethyl-1,2,4,5-tetrazine, Me(2)ttz) in [Ag(ttz)(X)] (X = NO(3), ; ClO(4), ), [Ag(2)(Me(2)ttz)(NO(3))(2)] (), [Ag(2)(Me(2)ttz)(H(2)O)(2)(ClO(4))(2)] (), [Ag(3)(Me(2)ttz)(H(2)O)(2)(CF(3)SO(3))(3)] () and [Cu(4)Cl(4)(Me(2)ttz)] (). In and , micro(4)-tetrazines and silver ions (AgN(4), Ag-N 2.42-2.53 A) compose a 3D framework of {4(2);8(4)} topology. Structures and were based on disilver-tetrazine ribbons, while in mu(4)-tetrazines interconnect silver-triflate chains. In , micro(4)-ligands connect inorganic layers sustained by copper-chloride squares, hexa- and octagons (1.974(2) and 1.981(2) A). Multiple N-coordination to metal ions enhances the ability of the electron deficient tetrazine system for anionpi binding. Compounds and exhibit very short interactions of this type with corresponding OC(N) separations down to a record value of 2.78 A and Opi 2.61 A. For , pi-acidity of tetrazine was reflected by contacts Clpi of 3.30 A. Results of high level ab initio calculations (RI-MP2/aug-cc-pVTZ) were in good agreement with experimental results, and were suggestive of the progressive enhancement of the pi-acidity by increasing the number of Ag(i) ions N-coordinated to tetrazine.

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Effects of p,,-pm conjugation in phosphaalkenes have

Reaction between [MCl,(dme)] ( M = W or Mo; dme = 1.2-dimethoxyethane) with Li, [C,H,CMe,C,H,] gave the ansa-bridged metallocene dichlorides [M{(q-C,H,)CMe,(q-C,H,)}CI,]( M = W or Mo). Treatment of these with LiAIH, or ZnMe, gave respectively the dihydrides [M{(q-C,H,)CMe,(q-C,H,)}H,] (M = W or Mo) and the dimethyl derivatives [M{(q-C,H,)CMe,(q-C,H,)}Me,](M = W or Mo).Treatment of [W{(q-C,H,)CMe,(q-C,H,))Me,] with HX (X = PhCO, or NHJ) gave [W{(q-C,H,)CMe,-(q-C5H4)}Me(Y)] with Y = PhCO, or I, respectively. Both of these react with Na[AIH,(OCH,CH,OMe),] giving the methylhydride [W{(q-C,H,)CMe,(q-C,H,)}Me(H)].The latter is thermally stable in refluxing benzene. Ultraviolet photolysis of [Mo{(q-C,H,)CMe,(q-C,H,))H,] in benzene gave the phenylhydride derivative [ Mo{ (q-CsH4) CMe,(q -C,H,)}Ph( H )I ; the corresponding tungsten derivative [W{ (q -C,H,) -CMe,(q-C,H,)}H,] is not photosensitive. The crystal structures of [W{(q-C,H,)CMe,(q-C5H4)}Cf2],[W{(q-C,H,)CMe,(q-CsH4)}H2], (two modifications) and [Mo{(q-C,H,)CMe,(q-C,H,)}H,] have been determined by X-ray diffraction. The ansa-bridged bis(q-cyclopentadienyl) compounds show marked differences in reactivity compared to non-ansa analogues and this is discussed in terms of the modifications of the electronic structure as a consequence of the ansa bridge.

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A series of functionalized adamantanes: 1,3-bis(1,2,4-triazol-4-yl)(tr(2)ad); 1,3,5-tris(1,2,4-triazol-4-yl)-(tr(3)ad); 1,3,5,7-tetrakis(1,2,4-triazol-4-yl)adamantanes (tr(4)ad) and 3,5,7-tris(1,2,4-triazol-4-yl)-1-azaadamantane (tr(3)ada) were developed as a new family of geometrically rigid polydentate tectons for supramolecular synthesis of framework solids. The coordination compounds were prepared under hydrothermal conditions; their structures reveal a special potential of the triazolyl adamantanes for the generation of highly-connected and open frameworks as well as structures based upon polynuclear metal clusters assembled with short-distance N(1),N(2)-triazole bridges. Complexes [Cd{L}(2)]A·nH(2)O [L = tr(3)ad, A = 2NO(3)(-) (4), CdCl(4)(2-) (5); L = tr(3)ada, A = CdI(4)(2-) (7)] are isomorphous and adopt a layered 3,6-connected structure of CdI(2) type. [{Cu(3)(OH)}(2)(SO(4))(5)(H(2)O)(2){tr(3)ad}(3)]·26H(2)O (6) is a layered polymer based upon Cu(3)(μ(3)-OH) nodes and trigonal tr(3)ad links. In [Cu(3)(OH)(2){tr(3)ada}(2)(H(2)O)(4)](ClO(4))(4) (8), [Cu(2){tr(3)ada}(2)(H(2)O)(3)](SO(4))(2)·7H(2)O (9) and [Cd(2){tr(3)ada}(3)]Cl(4)·28H(2)O (10) (UCl(3)-type net) the organic tripodal ligands bridge polynuclear metal clusters. Complexes [Ag{tr(4)ad}]NO(3)·3.5H(2)O (11) and [Cu{tr(4)ad}(H(2)O)](ClO(4))(2)·3H(2)O (12) have 3D SrAl(2)-type frameworks with the metal ions and adamantane tectons as topologically equivalent tetrahedral nodes, while in [Cd(3)Cl(6){tr(4)ad}(2)]·9H(2)O (13) the ligands bridge trinuclear six-connected Cd(3)Cl(6)(μ-tr)(4)(tr)(2) clusters. In the compounds [Cd(2){tr(2)ad}(4)(H(2)O)(4)](CdBr(4))(2)·2H(2)O (2) and [Cd{tr(2)ad}(4){CdI(3)}(2)]·4H(2)O (3) the bitopic ligands provide simple links between the metal ions, while in [Ag(2){tr(2)ad}(2)](NO(3))(2)·2H(2)O (1) the ligand is tetradentate and generates a 3D framework.