The significance of inorganic main-group polymers is demonstrated most clearly by the commercial relevance of polysiloxanes (silicones). Organoboron-based materials such as π-conjugated organoborane polymers and BN-doped polycyclic aromatic hydrocarbons are currently attracting considerable attention. Surprisingly, poly(iminoborane)s (PIBs; [BRNR'] ), that is, the parent unsaturated BN polymers, which are formally isoelectronic to polyacetylene, have not been convincingly characterized thus far. Herein, we present the synthesis and comprehensive characterization of a linear oligo(iminoborane), which comprises a chain of 12-14 BN units on average. With our synthetic approach, unwanted side reactions that result in borazine formation are effectively suppressed. Supporting DFT and TD-DFT calculations provide deeper insight into the microstructure and the electronic structure of the oligomer.

The reaction of n-C H B[N(Me)SiMe ] (1) with n-C H BCl (2 a) yielded, instead of a linear poly(iminoborane), the aminoborane n-C H B(Cl)N(Me)SiMe (4) and after cyclotrimerization the borazine cyclo-(n-C H BNMe) (6). Side reactions that result in borazine formation were effectively suppressed if 1,3-bis(trimethylsilyl)-1,3,2-diazaborolidines 7 were employed as co-monomers in combination with dichloro- or dibromoboranes 2 or 8, respectively. Silicon/boron exchange polycondensation led to oligo(iminoborane)s 11 a,b,ac,d. Alternative synthetic routes to such species involve Sn/B exchange of 1,3-bis(trimethylstannyl)-2-n-octyl-1,3,2-diazaborolidine (16) and n-C H BBr (8 a), and the initiated polycondensation of the dormant monomer 14 in the presence of a Brønsted acid (HCl, HOTf, or HNTf ; Tf=trifluoromethylsulfonyl). Although an attempt to obtain an oligo-/poly(iminoborane) with phenyl side groups yielded only insoluble material, the incorporation of aryl groups was proven for a derivative with both phenyl and n-octyl boron substituents (11 ac), as well as for a derivative with 4-n-butylphenyl side groups (11 d). The highest-molecular-weight sample obtained was 11 ac. Featuring about 18 catenated BN units, on average, this is the closest approach to a poly(iminoborane) known.

Fully aromatic, luminescent, and highly robust BNB-doped phenalenyls have been prepared, which are isoelectronic to the phenalenyl cation. B-Fluoromesityl-substitution leads to fluorescence in an extremely narrow range and significant increase...

Small changes to the reaction conditions differentiate between two metal–organic frameworks (MOFs), {[Ce2(H2O)(bpdc)3(dmf)2]·2(dmf)} n (1) and {[Ce4(H2O)5(bpdc)6(dmf)]·x(dmf)} n (2), that were solvothermally synthesized from cerium(III) nitrate hexahydrate and 2,2′-bipyridine-5,5′-dicarboxylic acid (H2bpdc) in dimethylformamide (dmf). The two compounds illustrate how the flexibility of the coordination geometry of CeIII translates into MOFs, the formation of which readily adapts to different solvent environments.