Novel Blue Phosphorescent Group 15 Compounds MR<sub>3</sub> (M = P, Sb, Bi; R = <i>p</i>-(<i>N</i>-7-Azaindolyl)phenyl)

New blue phosphorescent organometallic compounds of group 15, M[<i>p</i>-C<sub>6</sub>H<sub>4</sub>(<i>N</i>-7-azain)]<sub>3</sub> with M = P (<b>1</b>), Sb (<b>2</b>), Bi (<b>3</b>) and 7-azain = 7-azaindolyl, have been synthesized from the reaction of MCl<sub>3</sub> with Li[<i>p</i>-C<sub>6</sub>H<sub>4</sub>(<i>N</i>-7-azain)]. The crystal structures of these new compounds have been determined by single-crystal X-ray diffraction, which revealed that the group 15 elements in all three complexes are in a trigonal-pyramidal environment with the bond angles of C−M−C around the central atom decreasing from <b>1</b> to <b>3</b>, attributed to the diminution of s character of the M−C bond and the size increase of the central atom. All three compounds are blue luminescent. Both fluorescent and phosphorescent emissions (λ<sub>max</sub> = 371 nm, λ<sub>max</sub> = 488 nm) were observed for compound <b>1</b> at 77 K. In contrast, at 77 K, only phosphorescence was observed for compounds <b>2</b> and <b>3</b> (λ<sub>max</sub> = 483 nm for <b>2</b>; λ<sub>max</sub> = 478 nm for <b>3</b>), attributable to the increased heavy-atom effects. Experimental data and molecular orbital calculations (restricted Hartree−Fock methods) support the view that luminescences from all three compounds are ligand-based emissions with contributions from the lone-pair electrons of the central atom. The orange Bi(V) compound Bi[<i>p</i>-C<sub>6</sub>H<sub>4</sub>(<i>N</i>-7-azain)]<sub>3</sub>Cl<sub>2</sub> (<b>4</b>) was obtained by the oxidation of <b>3</b> with PhI·Cl<sub>2</sub>. Compound <b>4</b> displays a distorted-trigonal-bipyramidal structure and a weak phosphorescence at λ<sub>max</sub> = 510 nm at 77 K, which is most likely caused by charge-transfer transitions from the chloride ligand to the Bi(V) center.