title: Reactions of Sn(NMe2)2 with MPHCy: the effects of alkali metal phosphide coupling (Cy=cyclohexyl; M=Li, Na, K, Rb).
abstract: The reactions of the SnII 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=(Me2NCH2CH2)2NMe) gives [(NaPMDETA)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 Sn3 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 (NaPMDETA)2[{Sn(mu-PCy)}2(mu-PCyPCy)] (4) (containing one PCyPCy2- 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 {(K2 THF)2[{Sn(mu-PCyPCy)}2(mu-PCy)]}0.9{(K2 THF)2[{Sn(mu-PCy)}2(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 [RbPMDETA{(CyP)3SnP(H)Cy}] (6) (containing a cyclic {(CyP)3Sn} unit).
authors.affiliation: Chemistry Department, Cambridge University, Lensfield Road, Cambridge CB2 1EW, UK.
authors.forename: Paula
authors.initials: P
authors.lastname: Alvarez
authors.forename: Felipe
authors.initials: F
authors.lastname: García
authors.forename: Jörg P
authors.initials: JP
authors.lastname: Hehn
authors.forename: Florian
authors.initials: F
authors.lastname: Kraus
authors.forename: Gavin T
authors.initials: GT
authors.lastname: Lawson
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Korber
authors.forename: Marta E G
authors.initials: ME
authors.lastname: Mosquera
authors.forename: Mary
authors.initials: M
authors.lastname: McPartlin
authors.forename: David
authors.initials: D
authors.lastname: Moncrieff
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Pask
authors.forename: Anthony D
authors.initials: AD
authors.lastname: Woods
authors.forename: Dominic S
authors.initials: DS
authors.lastname: Wright