All manipulations were ciirried out under an argon atmosphere using standard vacuum-linc and Schlenk techniques. The solvents were freshly distilled under nitrogen from the appropriate drying reagents. Phosphonium and ammonium salts were dried in vacuum :it I X0 'C. Other reactants were used as received from the suppliers. 1 7 ZrX, (X = CI: 0.466 g. 2.0 mmol: X = Br: 0.822 g, 2.0 mmol) was reduced with Bu ,SnH I1 .OZ mL. 4.0 mmol) in benzene or toluene (20 mL) for 36 h. The resulting rcd-brown precipitate (dark blue for X = Br) was washed with two portions of freshly distilled toluene or benzene (each 10 mL) to remove excess Bu,SnH.Addition oI'R,A'X-in CH,CN or CH,CI, afforded 1 in about 30% yield. Approximately SO'!. of starting material was unredcted and isolated as [R,A],[ZrX,]. Addition of P R , to the red-brown precipitate yielded a purple solution of compound 6 and e purple precipitate. Compounds 2 were isolated in about 15% yield by dissolviiig thc purple precipitate in CH,CI, and layering with hexane. When phosphenes with ii higher number of carbon atoms (i.e., PBu,, P(lBu),Ph) were used. the only iwlable products from crystallization were compounds 3 in about I S % qield. Compounds 2 were converted into compounds 4 by treating with [R,A]'CI-in ober 90% yield. Compounds 2 were also converted gradually into compounds 5 in McCN solution at room temperature over a period of 30 days in about 50"4 yield. When compounds 2 were further reduced with Na/Hg in the prescnce of PR, compounds 7 were formed in yields of about 20%. ' H NMR rneiasurements were made at 200 MHz on a Varian XL-200 spectrometer. Hydridc signals were detected at 6 = ~ 3.07 for [Zr,CI,,HJ-and at 6 = -5.19 for [Zr,CI,,H,]" ~ in CH ,CN. X-ray data were collected on an Enraf-Nonius CAD-4 dii'fi-iictoineter or Enrdf-Nonius FR590 area detector. Full reports on the structures will be published elsewhere at a later time.
