Synthesis and structural characterization of main group 15 organometallics R3M and R(Ph)2P(=N-Ar) (M = P, Sb, Bi; R = phenanthrenyl; Ar=2,6-<SUP>i</SUP>Pr2-C6H3)

초록

New group 15 organornetallic compounds, M(phenanthrenyl)(3) (M = P (1), Sb (2), Bi (3)) have been prepared from the reactions of 9-phenanthrenyllithium with MCl3. A reaction of 9-(diphenylphosphino)phenanthrene with 2,6-diisopropylphenyl azide led to the formation of (phenanthrenyl)(Ph)(2)P=N-(2,6-(Pr2C6H3)-Pr-i) (4). The crystal structures of 2 and 4 have been determined by single-crystal X-ray diffractions, both of which crystallize with two independent molecules in the asymmetric unit. Compound 2 shows a trigonal-pyramidal geometry around the Sb atom with three phenanthrenyl groups being located in a screw-like fashion with an approximately C-3 symmetry. A significant amount of CH --- pi interaction exists between two independent molecules of 4. The phosphorus center possesses a distorted tetrahedral environment with P-N bond lengths of 1.557(3)angstrom (P(1)-N) and 1.532(3)angstrom (P(2)-N), respectively, which are short enough to support a double bond character. One of the most intriguing structural features of 4 is an unusually diminished bond angle of C-N-P, attributable to the hydrogen bonding of N(1)-H(5A) [ca. 2.49 angstrom] between two adjacent molecules in crystal packing. The compounds 1-3 show purple emission both in solution and as films at room temperature with emission maxima (lambda(max)) at 349, 366, and 386 urn, respectively, attributable to the ligand-centered pi -> pi* transition in phenanthrene contributed by the lone pair electrons of the Gp 15 elements. Yet the nature of luminescence observed with 4 differs in that it originates from pi (diisopropylbenzene)-pi* (phenanthrene) transitions with the p pi-contribution from the nitrogen atom. The emission maximum of 4 is red-shifted ranging 350-450 mu due to the internal charge transfer from the phenanthrenyl ring to the N-arylamine group as deduced from the ab initio calculations.

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