((Diaryl- and Dialkylphosphino)alkyl)cyclopentadienyl Ligands and Their Use in the Preparation of Heterobinuclear Ti/Mo and Zr/Mo Complexes

Abstract

The syntheses of a series of bifunctional ligands, in which a cyclopentadienyl and a phosphine group are linked by either a CH2 or a C2H4 fragment (-C5H4(CH2) n PR2; n = 1, 2; R = Me, Ph), are reported, as is that of the related ligand, Li2[Me2C(C5H3CMe2PPh2)2], in which both substituted cyclopentadienyl rings are linked by the CMe2 group. The metallocene dichloride complexes Cp‘2MCl2 (M = Ti, Zr; Cp‘2 = 2C5H4(CH2) n PPh2 (n = 1, 2), Me2C((C5H3)C(Me)2PPh2)2) have also been prepared, and the X-ray structure of (η5-C5H4(CH2)2PPh2)2ZrCl2 (7) has been determined. This complex has the pendent phosphinoalkyl arms close to eclipsed on the two C5H4 groups and bisecting the ZrCl2 angle, but bent in opposite directions away from the ZrCl2 plane. Reaction of 7 and its Ti analogue with (COD)Mo(CO)4 yields the heterobinuclear complexes [(μ-η5:η1-C5H4(CH2)2PPh2)2MCl2Mo(CO)4] (M = Ti, Zr). Structure determinations of these bimetallic complexes show the expected cis arrangement of phosphine moieties at Mo, M−Mo separations of 6.895 Å (M = Ti) and 6.945 Å (M = Zr), and MCl2 moieties aimed at right angles to the M−Mo vectors.

Tetranuclear, Early−Late Heterobimetallic Complexes Bridged by the Bifunctional Phosphinoalkylcyclopentadienyl Ligands [Ph2P(CH2)nC5H4]- (n = 1, 2)

“…As described previously, the group 4 metal complexes [(η 5 -C 5 H 4 (CH 2 ) n PPh 2 ) 2 MCl 2 ] ( n = 1, M = Ti ( 1 ), Zr ( 2 ); n = 2, M = Ti ( 3 ), Zr ( 4 )) can function as bidentate metalloligands generating heterobinuclear complexes in which the Cp‘ moiety (Cp‘ = C 5 H 4 (CH 2 ) n PPh 2 ) binds in an η 5 -manner to the earlier metal and the phosphine moiety binds to the later metal. Our investigation of ELHB complexes, in which Rh or Pd is the late metal, began with the preparation of [(μ-η 5 :η 1 -C 5 H 4 (C 2 H 4 )PPh 2 ) 2 TiCl 2 RhCl(CO)] 2 ( 5 ) by the slow addition of 3 to [RhCl(CO) 2 ] 2 at −80 °C under conditions of high dilution.…”

“…In a previous article we described the synthesis of a series of titanocene and zirconocene dihalide derivatives having a pendent phosphinoalkyl group attached to each cyclopentadienyl ring. Our goal was to utilize these (η 5 -C 5 H 4 (CH 2 ) n PR 2 ) 2 MCl 2 moieties (M = Ti, Zr; n = 1, 2; R = Me, Ph) as bidentate ligands in which the pendent phosphines would bind to late metals to generate early−late heterobimetallic (ELHB) complexes .…”

New Group 4 Metallocene and Niobocene Complexes Containing Phosphane-Functionalizedansa-Ligands

“…Solvents were distilled from appropriate drying agents and degassed before use. K(C 5 H 4 CH 2 CH 2 PPh 2 ),23 Li(C 5 H 4 PPh 2 )24 and [Nb(=N t Bu)Cl 3 (py) 2 ]25 were prepared as described earlier. [TiCl 4 (THF) 2 ], ZrCl 4 , HfCl 4 , Me 2 Si(C 5 Me 4 H)Cl, MgMeCl, B(C 6 F 5 ) 3 and (2,6‐dimethylphenyl)isocyanide were purchased from Aldrich and used directly.…”

Synthetic Inorganic Chemistry

“…The products are generated by displacement of the cyclooctadiene (COD) ligand by the organometallic chelating phosphine system. [57,58]…”