Osmacycles containing the {(Ph2PE)2N}− ligand (E=S or Se): synthesis and crystal structures

Abstract The reaction of (Ph 2 P) 2 NH (dppa) or Ph 2 PN(H)P(O)Ph 2 (HL) with [Os(η 6 -cym)Cl 2 ] 2 [cym= p -CH 3 C 6 H 4 CH(CH 3 ) 2 ] in THF affords the orange, neutral mononuclear complexes [OsCl 2 (η 6 -cym) P -dppa] ( 1a ) or [OsCl 2 (η 6 -cym) P -HL] ( 2 ), respectively, bearing a pendant PPh 2 or P(O)Ph 2 group. Complex 1a isomerises smoothly in CDCl 3 solution to give the cationic P , P ′-chelate complex [OsCl(η 6 -cym) P , P ′-dppa]Cl ( 1b ). Compound 2 can further be converted into the yellow P , O -chelate complexes [OsCl(η 6 -cym) P , O -HL][BF 4 ] ( 3 ) and [OsCl(η 6 -cym) P , O -L] ( 4 ) [L=Ph 2 PNP(O)Ph 2 ] upon treatment with either Ag[BF 4 ] or t BuOK, respectively. Chloro bridge cleavage of [Os(η 6 -cym)Cl 2 ] 2 with the potassium salt of either {Ph 2 P(S)} 2 N − or {Ph 2 P(Se)} 2 N − yields the orange neutral complexes [OsCl(η 6 -cym){ E , E ′-Ph 2 P(E)} 2 N] (E=S 5 , E=Se 6 ). All new compounds were characterised by a combination of NMR spectroscopy ( 1 H and 31 P{ 1 H}), IR spectroscopy, microanalysis and X-ray crystallography. The five- (OsPNPO) and six-membered (OsEPNPE) osmacycles represent the first examples of crystallographically characterised osmium(II) metallocycles.