Preparation and single-crystal characterization of manganese(II) complexesof dichalcogenoimidodiphosphinato ligands. Monomeric versus dimeric Mn[(OPPh2)(XPPh2)N](2) (X = S, O)

Manganese(II) compounds of the type Mn[(XPR2)(YPR2')N](2) (X, Y = O, S; R, R' = Me, Ph), were prepared by metathesis reactions between MnCl2. 4H(2)O a nd the alkaline salt of the corresponding ligand. IR data are consistent wi th the coordination of the phosphorus ligand in a deprotonated form. The ES R spectra exhibit resolved hyperfine structure only for the Mn[(OPMe2)(SPPh 2)N](2) derivative. The crystal and molecular structures of Mn[(OPPh2)(YPPh 2)N](2) (Y = O, S) were determined by X-ray diffractometry. The crystal of the tetraphenylthioimidodiphosphinato derivative contains monomeric, spiro- bicyclic Mn[(OPPh2)(SPPh2)N](2) units, with a distorted tetrahedral MnO2S2 core, as a result of monometallic biconnective phosphorus ligands. By contr ast, in the crystal of the tetraphenylimidodiphosphinato analogue distinct [Mn{(OPPh2)(2)N}(2)](2) dimers are present, in which the MnO5 core has a tr igonal bipyramidal geometry. The coordination pattern of the four imidodiph osphinato ligands differs. Two of them act as monometallic biconnective (ch elating) units, leading to six-membered MnO2P2N rings. The other two ligand s act as bimetallic triconnective units, which results in a fused tricyclic Mn2O4P4N2 system. The central four-membered Mn,O, ring is slightly bent [M n(1)O(5)O(8)/Mn(2)O(5)O(8) dihedral angle 23.9 degrees]. The overall confor mation of the [Mn{(OPPh2)(2)N}(2)](2) dimer might be described as cis, i.e. with six-membered MnO2P2N rings formed by ligands of the same type placed on the same side of the four-membered Mn2O2 ring. (C) 2000 Elsevier Science S.A. All rights reserved.