LEWIS-BASE ADDUCTS OF LEAD(II) COMPOUNDS .17. SYNTHETIC AND STRUCTURAL STUDIES OF SOME 1 1 ADDUCTS OF 2,2'/6,2''-TERPYRIDINE WITH LEAD(II) SALTS/

Syntheses and room-temperature single-crystal X-ray structure determin ations are recorded for 1:1 adducts of 2,2':6',2 ''-terpyridine ('tpy' ) with the lead(II) oxoanion salts perchlorate: nitrate and nitrite, ( tpy)Pb(oxoanion)(2). All structures are monoclinic, C2/c, Z = 4, with approximate ranges a from 9 to 11 Angstrom, b from 16 to 20 Angstrom, c from 9.8 to 13.8 Angstrom, beta from 113 to 130 degrees and V from 1 650 to 1850 Angstrom(3). In all cases the lead(II) atoms are disposed on crystallographic 2 axes which also pass through the axis of the cen tral tpy ring; a pair of symmetry-related oxoanions link successive le ad atoms in a one-dimensional polymeric chain parallel to the ac cell diagonal, one pair of oxygen atoms functioning as an O,O'-bidentate wi th another oxygen (replaced by the nitrogen in the nitrite) bridging t o the adjacent lead atom; the third anionic oxygen atom in the nitrate is replaced by a water molecule in the nitrite, which thus becomes a monohydrate. Residuals were 0.030, 0.034 and 0.040 for 2122, 1564 and 2059 independent 'observed' (I > 3 sigma(I)) reflections respectively. Also recorded are the syntheses and room-temperature single-crystal X -ray structure determinations for 1:1 aducts of 2,2':6',2 ''-terpyridi ne with lead(II) chloride, bromide and iodide, the chloride and bromid e being hydrated. (tpy)PbCl2.H2O is monoclinic, P2(1)/c, a 8.938(1), b 15.210(7), c 13.414(3) Angstrom, beta 115.17(1)degrees, Z = 4 f.u.; R was 0.036 for N-o = 3346 independent, 'observed' reflections. The com plex is centrosymmetric, binuclear [(tpy)(H2O)(Cl)Pb(mu-Cl)(2)Pb(Cl)(O H2)(tpy)], with the two lead atoms linked by bridging chlorine atoms; the lead atoms are seven-coordinate N-3,O,ClPb(mu-Cl)(2), The bromide (tpy)PbBr2.2/3H(2)O, triclinic, <P(1)over bar>, a 12.360(6), b 12.452( 4), c 18.372(6) Angstrom, alpha 108.31(3), beta 109.44(3), gamma 90.56 (3)degrees, Z = 6 f.u., R being 0.046 for N-o 7282, is in fact trinucl ear [Pb3Br6(tpy)(6)].2H(2)O, a novel and elegant oligomer with quasi-2 symmetry in which a central lead atom (on the quasi-2 axis) is seven- coordinated [(tpy)Pb(mu-Br)4] with the associated bromides bridging to a pair of peripheral lead atoms, also seven-coordinated, [(tpy)(Br)Pb (mu-Br)(3)]. Unsolvated (tpy)PbI2, triclinic, <P(1)over bar>, a 10.834 (3), b 9.023(3), c 8.906(2) Angstrom, alpha 80.34(2), beta 89.40(2), g amma 79.78(2)degrees, Z = 2 f.u., R 0.031 for N-o 2347 is, like the ch loride, centrosymmetric binuclear, [(tpy)(I)Pb(mu-I)(2)Pb(I)(tpy)], bu t with the lead(II) now six-coordinate N-3(I)Pb(mu-I)(2). In both chlo ride and iodide, the tpy plane is approximately normal to the Pb ... P b line with the water molecule of the chloride approximately trans to the central tpy nitrogen; in the iodide that site is occupied by the t erminal halide.