Compounds double-bridged

The structure of coordination polymers formed with 3,6-bis(pyridin-3-yl)-l,2,4,5-tetrazine and zinc salts can be controlled by the choice of alcoholic solvents. Infinite lattice compounds of the form [Zn2L2(N03)4(Me0H)2(//-L)] and [Zn2(/U-L)3(N03)4](CH2C12)2) have been structurally characterized. The former structure shows an alternating single- and double-bridged species whereas the latter exists as a non-interpenetrated ladder complex.273... 

The trans-bent structure was unexceptional and found to be energetically favored compared to the linear arrangement, but even more stable forms such as vinylidene, mono-bridged or double-bridged isomers exist. Compounds 392-395 are unexceptional monomeric in solution, as is typical for M(i) cluster compounds.297... 

Haber process, 116 Hafnium complexes alkyl alkoxy reactions, 358 phthalocyanines, 865 porphyrins, 823 pseudohalides, 228 Hafnium(IV) complexes cupferron, 512 Haloarsine compounds, 1004 Halogen complexes, 675-687 bridge systems, 677-684 asymmetry, 678 theoretical studies, 682 double bridged, 681... 

Cyclopentadienyl systems bridged by a single silicon-containing unit are described in Section II.E.l. Cyclopentadienyl units which are held together by a double bridge are described in Section II.E.2. Section II.E.3. describes cooperative effects exerted by dimethylsilyl groups as bridging units, with special emphasis on polyferrocenyl compounds. 

Double bridges Pd2(/r-X)2 are formed very frequently, but less stable single bridges Pd2(/r-X) are also known. Dimeric compounds are the most abundant, but trimeric derivatives [L2Pd(/r-X)2Pd(/r-X)2PdL2] + and compounds with higher nuclearity have been prepared. 

Compounds 10a 13c), 11 (13e), 12 (13g), and 13 (13), while monomeric, have the same general geometrical features as those found in 5-9, and can be regarded as examples of intramolecular association. That is, two lithium atoms are involved in a symmetrical double-bridging arrangement between benzylic (10a and 11) and aryl (12 and 13) sp carbon atoms, respectively. 

Bredt s rule In small bridged bicyclic compounds, double bonds are impossible at the bridgehead. Small means that the S number must be less than or equal to six. The S number is the sum of the number of atoms in the bridges of a bicyclic system. If the S number is equal to seven, then if the double bond is in a seven-membered ring it cannot be formed it can be formed, however, if it is in an eight-membered ring. 

Compound 15 to 17 have binuclear cations in which the two metal atoms are bridged by two H3O2 ligands as in Fig. 8 and Fig. 9. Such double bridging is possible only if the two oxygen ligands are in cis positions. In compound 21, which is also a cis isomer, the formation of this double bridge is blocked by the dithionate counterion (Fig. 12). The... 

The mechanism of olation in the solid state, proposed in Sect. VII, was confinned the fact that only cis-hydroxoaqua complexes olate was ascribed to their doubly-bridged dimeric structure. A direct conclusion from this hypothesis is that any hydroxoaqua complex that does not have such a dimeric structure, should not olate. This conclusion was confinned in two cases the only complex of this type which was known not to have a dinuclear structure (compound 21, Table 3, Ref. 29), does not olate even at 200°C and is decomposed at higher temperatures . When the dythionate counter ion in this salt was replaced by iodide, a normal, double-bridged dimer was obtained ... 

Scheme 5 illustrates the conformational complexity which is built into symmetrical IV compounds that have unsymmetrical M groups attached to symmetrical bridges by single bonds. Rotation about these bonds interconverts syn and anti conformations of the M groups. For these compounds, double nitrogen inversion also interconverts syn and anti ferf-butyl group conformations, so there are four diastereomeric conformations of 18. All are present in equal amounts for neutral 18,... 

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