No abstract

for the structurally characterized complex trans- [MoOCl-(dppe)2]Cl (v(Mo=0) at 942 cm"1).24 CV's of solutions of these complexes in 0.1 M TBAH/CH2C12 revealed the presence of a reversible one-electron reduction at £j/2 = -1.17 V (X = Cl) and £j/2 = -1.10 V (X = Br) and an irreversible oxidation at £p_a = +1.8 V (X = Cl) and +1.9 V (X = Br) vs Ag/AgCl. Irreversible processes associated with the oxidation of the outer-sphere halide ion are also seen (Table IV).The 3IP|1H| NMR spectra of these complexes recorded in CD2C12 exhibit a singlet at +48.8 (X = Cl) and +47.6 (X = Br). These chemical shifts are characteristic of five-membered rings formed by chelating phosphines.25 The NMR spectra of [MoOX(dppbe)2]X-«H20 (X = Cl, Br) recorded in CD2C12 showed the expected phenyl ring resonances between +8.8 and +6.5. These spectra are almost identical with one another.The low-frequency IR spectrum (Nujol mull) for [MoOCl-(dppbe)2]Cl-3H20 exhibits a strong absorption at 293 cm"1, which is probably due to the v(MoCl) mode. A similar band (at ~290 cm"1) is seen the spectrum of the analogous PF6" salt.D. Consideration of Reactivities. In view of previous observations concerning the occurrence of chelating (

No abstract

No abstract

The 1,2,3-diazaphosphole /5~C(H)C(Me)~N~Me (La) and the 1,2,4,3-triazal~hospholes i~iLlq(?(]~i~)~N~,tMe (Ln) and f*~NN(M6)C'(Mo)~=~ (Lc) lbrm Pt{ II) and Pd(ll) complexes of stoichiometry MX2(PEh)L (X = Cl, Br) whose controlled reactions with alcohols, generally methanol, have been studied by ttl, ~tp and t"SPt NMR spectroscopy. Discrete intermediate species and the tinal novel monomeric phosphito metallacycles (tr-F' bonding of it I P(=O) (OR)R'} ..... function and N-coordination of either an imine or amine Iunction) have been identilied by Iheir characteristic multinuclear NMR data. These data allow a stepwise mechanism for the azaphosphole ring,.opctm~g to be proposed, Two rcprcsc|ltalivc produ~:ts o1 lhc series derived from I, n and L o namely [PI{P( ~O)(OMc)N{ H)-('( Ph),,,,,NN( I! )Me} (CI) t PEtt) I (19c) and I PtIP(~O) {OMc) N( II )NI Me)C( Mc):~Ntl } (CI) (PEt~) I (20c) I/~lvc bccn char;lctcrizcd by X.ray slrucltlrC invcstigMions, I11 the crystal the botlding of tile P,N..chclatitig lit, and in 119e is tlil'ft~rc|~l tO that idcimficd in ~oltmtion; the two !igattd iorms I'o.und c~111 be described ht t0rnts of :unidiltC talllOllleriSM, t III this paper for simplicity we refer to ;i { P( ~,' O) ( OR ) R' } li~itnd as a Ifl~osphitc; Ibis is strictly only COl'lCt:t i/R is ( bonded Ihrotlgh) ;m clcclroncgativc t~lcl|101ll illitl ill t?IlSC.~ whcl'c i~ ts (?bound Ihc li~;md l:, mote ptop~:tiy ;t phosl~hmilc, ) (O 1~)97 iEl.~icvicr Science S,A.