Abstract
Reactions of Cp™HPPh2 (1, diphenyl(4,4,6,6-tetramethyl-1,4,5,6-tetrahydropentalen-2-yl)phosphane) with the organic azides AdN3 and DipN3 (Ad = 1-adamantyl; Dip = 2,6-di-iso-propylphenyl) led to the formation of two novel CpPN ligands: P-amino-cyclopentadienylidene-phosphorane (Cp™PPh2NHAd; L(Ad)H) and P-cyclopentadienyl-iminophosphorane (Cp™HPPh2NDip; L(Dip)H). Both were characterized by NMR spectroscopy and X-ray structure analysis. For both compounds only one isomer was observed. Neither possesses any detectable prototropic or elementotropic isomers. Reactions of these ligands with [Lu(CH2SiMe3)3(thf)2] or with rare-earth metal halides and three equivalents of LiCH2SiMe3 produced the desired bis(alkyl) Cp™PN complexes: [{Cp™PN}M(CH2SiMe3)2] (M = Sc (1(Ad), 1(Dip)), Lu (2(Ad), 2(Dip)), Y (3(Ad), 3(Dip)), Sm (4(Ad)), Nd (5(Ad)), Pr (6(Ad)), Yb (7(Ad))). These complexes were characterized by extensive NMR studies for the diamagnetic and the paramagnetic complexes with full signal assignment. An almost mirror inverted order of the paramagnetic shifts has been observed for ytterbium complex 7(Ad) compared to 4(Ad), 5(Ad) and 6(Ad). For the assignment of the NMR signals [{η(1) : η(5)-C5Me4PMe2NAd}Yb(CH2SiMe3)2] 7 was synthesized, characterized and the (1)H NMR signals were compared to 7(Ad) and to other paramagnetic lanthanide complexes with the same ligand. 1(Ad), 2(Ad), 2(Dip), 3(Ad) and 3(Dip) were characterized by X-ray structure analysis revealing a sterically congested constrained geometry structure.
Highlights
The organometallic chemistry of the rare-earth metals began in the middle of the last century with the synthesis of their tris(cyclopentadienyl) derivatives by Wilkinson and Birmingham.[1]
In this work we describe the synthesis, NMR studies and molecular structures of two novel cyclopentadienyl-phosphazene (CpPN) ligands with a tetrahydropentalene unit: CpTMPPh2NHAd (LAdH) and CpTMHPPh2NDip (LDipH)
TlCp by NaCp, which can be synthesized on a large scale out of Na and (CpH)2.25 The improved ligand synthesis is following the condensation of NaCp with one Ph2PCl and two acetone molecules, which are cheap starting materials making the final CpTMPN ligand very attractive as an alternative for commonly used but expensive ligands with a C5Me4R moiety
Summary
The organometallic chemistry of the rare-earth metals began in the middle of the last century with the synthesis of their tris(cyclopentadienyl) derivatives by Wilkinson and Birmingham.[1]. In this work we describe the synthesis, NMR studies and molecular structures of two novel cyclopentadienyl-phosphazene (CpPN) ligands with a tetrahydropentalene unit: CpTMPPh2NHAd (LAdH) and CpTMHPPh2NDip (LDipH).
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