Pyridineselenolate Complexes of Tin and Lead: Sn(2-SeNC₅H₄)₂, Sn(2-SeNC₅H₄)₄, Pb(2-SeNC₅H₄)₂, and Pb(3-Me₃Si-2-SeNC₅H₃)₂. Volatile CVD Precursors to Group IV−Group VI Semiconductors

Abstract

Pyridineselenolate forms stable homoleptic coordination compounds of Sn(II), Sn(IV), and Pb(II). The complexes can be prepared either by metathesis or by insertion of the metal into the Se-Se bond of dipyridyl diselenide, and they are soluble in coordinating solvents such as pyridine. Isolation of the Pb(II) complex from both Pb(0) and Pb(IV) starting materials indicates that the pyridineselenolate ligand cannot stabilize Pb(IV). The compounds all sublime intact and decompose at elevated temperatures: the divalent complexes give MSe (M = Sn, Pb), while the Sn(IV) compound delivers SnSe(2). In order to isolate a crystalline Pb compound, the 3-trimethylsilyl-2-pyridineselenolate ligand was prepared. Attachment of the Me(3)Si functional group increases compound solubility, and leads to the isolation of crystalline Pb(3-Me(3)Si-2-SeNC(5)H(4))(2). The structure of [Sn(2-SeNC(5)H(4))(2)](2) (1) was determined by single-crystal X-ray diffraction and shown to be a dimer, with one chelating pyridineselenolate per Sn(II) and a pair of pyridineselenolates that asymmetrically span the two metal centers to form an eight membered (-Sn-Se-C-N-Sn-Se-C-N-) ring, with weak Sn-Se interactions connecting the dimeric units. Crystal data for 1 (Mo Kalpha, 298(2) K): orthorhombic space group Pbca, a = 8.214(1) Å, b = 21.181(3) Å, c = 14.628(2) Å.