Unexpected P−Si or P−C Bond Cleavage in the Reaction of Li₂[(C₅Me₄)SiMe₂PR] (R = Cyclohexyl, 2,4,6-Me₃C₆H₂) and Li[(C₅H₄)CMe₂PHR] (R = Ph,^tBu) with ZrCl₄or [TiCl₃(thf)₃]:  Formation and Molecular Structure of the<i>ansa</i>-Metallocenes [{(η-C₅Me₄)₂SiMe₂}ZrCl₂] and [{(η-C₅H₄)₂CMe₂}MCl₂] (M = Ti, Zr)

Abstract

The (phosphinosilyl)cyclopentadiene 1-SiMe 2 PHMes-2,3,4,5-Me 4 C 5 H, prepared from 1-SiMe 2 Cl-2,3,4,5-Me 4 C 5 H and LiPHMes (Mes = 2,4,6-Me 3 C 6 H 2 ), reacts with MeLi to yield Li 2 [(C 5 Me 4 )SiMe 2 PMes] ( 2 ). The (phosphinomethyl)cyclopentadienide Li[(C 5 H 4 )CMe 2 PH t Bu] ( 4 ) is obtained by the reaction of LiPH t Bu with 6,6-dimethylfulvene. Li 2 [(C 5 Me 4 )SiMe 2 PR] (R = cyclohexyl (Cy; 1 ), Mes ( 2 )) reacts in situ with ZrCl 4 at −30 °C to give [{(η-C 5 Me 4 ) 2 SiMe 2 }ZrCl 2 ] ( 5 ). The formation of (PCy) 4 and (PHMes) 2, respectively, in these reactions was shown by 31 P NMR spectroscopy. In the reaction of Li[(C 5 H 4 )CMe 2 PHR] (R = Ph ( 3 ), t Bu ( 4 )) with ZrCl 4 or [TiCl 3 (thf) 3 ], [{(η-C 5 H 4 )CMe 2 PHR} 2 ZrCl 2 ] (R = Ph ( 6 ), t Bu ( 7 )) and [{(η-C 5 H 4 )CMe 2 PHR} 2 TiCl] (R = Ph ( 9 ), t Bu ( 10 )) are formed. 6, 7, 9, and 10 slowly decompose on recrystallization from thf, Et 2 O, or toluene with formation of [{(η-C 5 H 4 ) 2 CMe 2 }MCl 2 ] (M = Zr ( 8 ), Ti ( 11 )). The formation of (PR) n (R = Ph, n = 4−6; R = t Bu, n = 4) and PH 2 R was shown by 31 P NMR spectroscopy. 2, 4, 5 − 8, and 11 were characterized by NMR spectroscopy ( 1 H, 13 C, 31 P) and the paramagnetic Ti(III) complexes 9 and 10 by EPR spectroscopy and mass spectrometry. 5, 8, and 11 were also characterized by crystal structure determinations.