Zusammenfassung
The reactions of the Sn-II base Sn(NMe2)(2) with CyPHM (Cy=cyclohexyl) produce a range of products, depending primarily on the alkali metal (M) involved. The 1:3 stoichiometric reaction of Sn(NMe2)(2) with CyPHNa in the presence of the Lewis base donor PMDETA (PMDETA=Me2NCH2- CH2)(2)NMe) gives [(Na(.)PMDETA)(2){Sn-(mu-PCY)}(3)] (3), containing the electron-deficient [(Sn(mu-PCy)(3)](2-) dianion. ...
Zusammenfassung
The reactions of the Sn-II base Sn(NMe2)(2) with CyPHM (Cy=cyclohexyl) produce a range of products, depending primarily on the alkali metal (M) involved. The 1:3 stoichiometric reaction of Sn(NMe2)(2) with CyPHNa in the presence of the Lewis base donor PMDETA (PMDETA=Me2NCH2- CH2)(2)NMe) gives [(Na(.)PMDETA)(2){Sn-(mu-PCY)}(3)] (3), containing the electron-deficient [(Sn(mu-PCy)(3)](2-) dianion. Natural bond order (NBO) and electron localisation function (ELF) calculations show that this species is described most appropriately by a two-electron, three-centre Sn-3 bonding model. Evidence that 3 results from phosphide coupling is provided by the 1:1 reaction of Sn(NMe2)(2) with CyPHNa in the presence of PMDETA, which gives 3 and trace amounts of (Na-PMDETA)(2)[{Sn(mu-PCy)}(2)( mu-PCyPCy)] (4) (containing one pCypCy(2-) dianion). Greater extents of phosphide coupling are observed as the size of the Group 1 metal is increased. Thus, the 1:3 reaction of Sn(NMe2)(2) with CyPHK in THF gives the co-crystalline product {(K(.)2THF)(2)[{Sn(mu-PCyPCy)}(2)( mu-PCy)]}(0.9){(K(.)2THF)(2)[{Sn-(mu-PCy)}(2)[{Sn-(mu-PCyPCy]}(0.1) (5) (containing [{Sn(mu-PCyPCy)}(2)(mu-pCy)](2-) and [{Sn(mu-PCy)}(2)(mu-PCyPCy)](2-) dianions), whereas the analogous reaction of Sn(NMe2)2 with RbPHCy gives [Rb(.)PMDETA{(CyP)(3)SnP(H)Cy}] (6) (containing a cyclic {(CYP)(3)Sn} unit).
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