Syntheses and X-ray structures of potassium derivatives and a paramagnetic nickel(II) complex of a cyclodiphosph(III/V)azane monoselenide.
The cyclodiphosph(III/V)azane monoselenide [(t)Bu(H)N(Se)P(micro-N(t)Bu)(2)PN(H)(t)Bu] (6, H(2)cdppSe where cdpp = cyclodiphosphazane) is obtained in quantitative yield from the comproportionation reaction of equimolar amounts of H(2)cdpp (7) and H(2)cdppSe(2) (3) in toluene at 85 degrees C. The X-ray structures of 3 and 6 reveal that both the monoselenide and the diselenide adopt a cis,endo,exo arrangement of the (t)BuNH groups. Metalation of 6 with 1 equiv of KO(t)Bu or 2 equiv of KCH(2)Ph in THF produces [(THF)K[HcdppSe]](2) (8) or [[(THF)(2)K](2)[cdppSe]](2) (9), respectively. The initial deprotonation involves the (t)BuNH group attached to the P(V) center in 6. In the dimeric structure of 8, both of the monoanionic ligands are bis-N,Se-chelated to the two K(+) cations to give a distorted K(2)N(2)Se(2) octahedron. In the centrosymmetric dimer 9, the dianionic ligands adopt two different coordination modes to the bis-solvated K(+) ions, viz., tridentate N,N',N" coordination and N,Se-chelation involving both exo- and endocyclic nitrogen atoms. The dimer is linked through K-Se interactions. The reaction of 2 equiv of 8 with NiCl(2)(PMe(3))(2) in THF produces [Ni(HcdppSe)(2)], which has a distorted tetrahedral structure and exhibits anomalous (1)H, (13)C, and (31)P NMR chemical shifts owing to the proximity of the paramagnetic Ni(II) center.
Department of Chemistry, University of Calgary, Calgary, Alberta, Canada T2N 1N4. chivers@ucalgary.ca
Tristram
T
Chivers
Mark
M
Krahn
Gabriele
G
Schatte