Organolead(IV) derivatives of oxophosphorus ligands.: X-ray structures of monomeric R 2Pb[(OPPh 2) 2N] 2 (R=Me, Ph) and tetrameric [Me 3Pb(O 2PPh 2)] 4

Abstract

The reaction of R 4− n PbCl n with Na[(OPPh 2) 2N] or K[(OPPh 2)(SPPh 2)N] afforded isolation of Ph 2Pb[(OPPh 2) 2N] 2 ( 1), Ph 2Pb[(OPPh 2)(SPPh 2)N] 2 ( 2), Me 3Pb[(OPPh 2) 2N] ( 3) and Ph 3Pb[(OPPh 2)(SPPh 2)N] ( 4). Attempts to grow crystals of Me 3Pb[(OPPh 2) 2N] ( 3) led to isolation of Me 2Pb[(OPPh 2) 2N] 2 ( 5), as a result of decomposition. Me 3Pb(O 2PPh 2) ( 6) was obtained from Me 3PbCl and Na(O 2PPh 2). The compounds were characterized by IR and multinuclear NMR spectroscopy. The molecular structures of 1, 5 and 6 were determined by single-crystal X-ray diffraction. The crystal of 5 contains two independent molecules in the unit cell. In both compounds the imidodiphosphinato ligands act as monometallic biconnective units, resulting in a spiro-bicyclic system with six-membered PbO 2P 2N rings of distorted boat conformation. The coordination geometry around the metal atom is distorted octahedral, with CPbC angles close to 180° [178.9(2)° for 1; 173.4(3)° and 178.7(4)° for molecules 5a and 5b, respectively]. The crystal of the trimethyllead(IV) phosphinate ( 6) contains discrete tetrameric units, [Me 3Pb(O 2PPh 2)] 4, with bridging phosphinato ligands [range: PbO 2.373(3)–2.402(6) Å, PO 1.495(6)–1.512(6) Å], thus resulting in a sixteen-membered Pb 4O 8P 4 inorganic ring. The coordination geometry at lead atoms is distorted trigonal bipyramidal, with oxygen atoms in trans positions [range: OPbO 174.7(2)–177.6(3)°].