Organometallic Niobium and Tantalum Complexes with Primary Phosphine Ligands: Syntheses and Molecular Structures of [Cp*MCl4(PH2R)] (M = Nb, Ta; Cp* = C5Me5;R = But, Ad, Cy, Ph, 2, 4, 6-Me3C6H2 (Mes))

Abstract

The reaction of [Cp*MCl 4 ] (M ϭ Nb, Ta; Cp* ϭ C 5 Me 5 ) with PH 2 R in toluene at room temperature gives the primary phosphine complexes [Cp*MCl 4 (PH 2 R)] [Cp* ϭ C 5 Me 5 ; M ϭ Nb: R ϭ Bu t (1a), Ad (2a), Cy (3a), Ph (4a), 2,4,6-Me 3 C 6 H 2 (Mes) (5a); M ϭ Ta: R ϭ Bu t (1b), Ad (2b), Cy (3b), Ph (4b), Mes (5b)] in high yield. 1؊5 were characterized spectroscopically (NMR, IR, MS) and by Metallorganische Niob-und Tantal-Komplexe mit primären Phosphanliganden: Synthese und Molekülstrukturen von [Cp*MCl 4 (PH 2 R)] (M ‫؍‬ Nb, Ta; Cp* ‫؍‬ C 5 Me 5 ; R ‫؍‬ Bu t , Ad, Cy, Ph, 2,4,6-Me 3 C 6 H 2 (Mes)) Inhaltsübersicht. Die Komplexe [Cp*MCl 4 ] (M ϭ Nb, Ta; Cp* ϭ C 5 Me 5 ) reagieren bei Raumtemperatur in Toluol mit den primären Phosphanen PH 2 R unter glatter Bildung der Verbindungen [Cp* MCl 4 (PH 2 R)] [Cp* ϭ C 5 Me 5 ; M ϭ Nb: R ϭ Bu t (1a), Ad (2a), Cy

Cyclopentadienyl Tantalum(V) Complexes with Primary and Secondary Ferrocenylphosphine Ligands

“…The 31 P NMR spectroscopic data of compounds 2Ϫ5 are shown in Table 2. As expected on coordination to a tran- [28]. The differences in the chemical shift between the free phosphine and the respective tantalum(V) complex are larger for the primary ferrocenylphosphines than for the secondary (FcCH 2 ) 2 PH.…”

“…As we already observed in previous investigations on tantalum phosphine complexes [28], the quadrupole momentum of the Ta atom causes extreme line broadening in the 31 P NMR spectra of the tantalum ferrocenylphosphine complexes at room temperature. The very short relaxation time at room temperature can be followed in the FID of the complexes (see Fig.…”

“…Recently, we published the crystal structure of [Cp*TaCl 4 ] (1a) [28], one of our starting materials, whose monomeric molecular structure is apparently due to the large Cp* ligand. We therefore invested some effort in crystallising the related tantalum complex [CpЈTaCl 4 ], whose CpЈ ring is sterically less demanding, and which until today was only known as a yellow powder.…”

“…Up to now, only a few phosphine complexes of cyclopentadienyl tantalum tetrachloride are known, all but one of which have tertiary phosphine ligands [24d, 25Ϫ27]. We reported the synthesis of [CpЈTaCl 4 (PH 2 Tipp)] (CpЈ ϭ C 5 MeH 4 , Tipp ϭ 2,4,6-Pr i 3 C 6 H 2 ), which was the first cyclopentadienyl tantalum tetrachloride complex with a primary phosphine [14a], and a number of other tantalum and niobium complexes with primary phosphine ligands [28]. We have already shown that the phosphines PH 2 Fc [Fc ϭ Fe(η 5 -C 5 H 5 )(η 5 -C 5 H 4 )] [29], PH 2 CH 2 Fc [3,4] and PH(CH 2 Fc) 2 [10] (ϭ L) react with transition metal complexes with reactive MϪX bonds (X ϭ halide) without loss of HX but with clean formation of the corresponding phosphine complexes, such as [(p-cymene)RuCl 2 (L)] (p-cymene ϭ 1-Me-4-Pr i C 6 H 4 ) [3,30,31], [MI 2 (CO) 3 L 2 ], [MI 2 (CO) 2 L 3 ] (M ϭ Mo, W) [32,33,34], and [WI(CO) 2 L 4 ]I (L ϭ PH 2 CH 2 Fc) [35].…”

Synthesis of novel paracyclophanes with linear P,N-containing spacers

“…The positive ion MALDI TOF mass spectrum of com pound 5 showed a molecular ion peak with m/z 804 corresponding to the condensation product 3, 21 Like the spectrum of the reaction mixture, the 31 P NMR spectrum of compound 5 contained two closely spaced signals at δ -41.25 and -41. 30. They suggest that cyclo phane 5 is a mixture of the cis and trans stereoisomers.…”