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The molecular meso-metallaporphyrin has been obtained from the reaction of AlMe3with the bulky 4,5-(Ph2(HO)C)2-1,2,3-triazole (1). The presence of Al–Me groups coordinated to the triazole rings creates three different stereoisomers that were identified by single-crystal X-ray diffraction. Further studies revealed that, for steric reasons, only one of the two main stereoisomers is active in the polymerization of ε-caprolactone. When GaMe3is used instead of AlMe3, a trimetallic species is formed instead of the meso-metallaporphyrin pointing to a metal-directed self-assembly. On the other hand, the reaction of the monolithium salt [{Li(THF)2}{κ2-N,N′-4,5-(Ph2(HO)C)-1,2,3-triazole}]2(2; THF = tetrahydrofuran) with MCl3(M = Al, Ga) yields meso-metallaporphyrin species with a lithium atom in the center of the metallacycle. While the gallium derivative is rather stable in solution, the aluminum analogue decomposes rapidly. In the solid state, continuous cationic columns running throughout the whole crystal are formed from alternating Li⊂[M]4(M = Al, Ga) meso-metallaporphyrin and [Li(THF)4]+cations. Density functional theory calculations determined that the weak Cl···H, H···H, N···H, and Cl···O interactions with a total interaction energy of −38.6 kcal·mol–1are responsible for this unusual packing.

A series of borosilicates was synthesized, where the structure of the borosilicate core was easily modulated using two strategies: blocking of condensation sites and controlling the stoichiometry of the reaction. Thus, on the one hand, the condensation of phenylboronic or 3-hydroxyphenylboronic acid with diacetoxysilylalkoxide [(tBuO)(Ph3CO)Si(OAc)2] led to the formation of borosilicates (tBuO)(Ph3CO)Si{(μ-O)BPh}2(μ-O) (1), [{(tBuO)(Ph3CO)Si(μ-O)BPh(μ-O)}2] (2), and [{(tBuO)(Ph3CO)Si(μ-O)B(3-HOPh)(μ-O)}2] (3) with a cyclic inorganic B2SiO3or B2Si2O4core, respectively. On the other hand, the reaction of phenylboronic acid with triacetoxysilylalkoxide (Ph3CO)Si(OAc)3in 3:2 ratio resulted in the formation of a cagelike structure [{(Ph3CO)Si(μ-O)2BPh(μ-O)}2] (4) with B4Si4O10core, while the reaction of the boronic acid with silicon tetraacetate generated an unusual 1,3-bis(acetate)-1,3-diphenyldiboraxane PhB(μ-O)(μ-O,O′-OAc)2BPh (5). Additionally, compound 1was used to evaluate the possibility to form N→B donor–acceptor bond between the boron atom in the borosilicates and a nitrogen donor. Thus, coordination of 1with piperazine yielded a tricyclic [{(tBuO)(Ph3CO)Si(OBPh)2(μ-O)}2·C4H10N2] compound 6with two borosilicate rings bridged by a piperazine molecule. Finally, the processes involved in the formation of the six- and eight-membered rings (B2SiO3and B2Si2O4) in compounds 1and 2were explored using solution 1H NMR studies and density functional theory calculations. These molecules represent to the best of our knowledge first examples of cyclic molecular borosilicates containing SiO4units.