Synthesis of neutral and zwitterionic phosphinomethylpyrrolato complexes of nickel

A Germylene Supported by Two 2‐Pyrrolylphosphane Groups as Precursor to PGeP Pincer Square‐Planar Group 10 Metal(II) and T‐Shaped Gold(I) Complexes

“…We prepared HpyrmP t Bu 2 by heating 2‐dimethylaminomethylpyrrole (HpyrmNMe 2 ) with t Bu 2 PH in the absence of any solvent at 135 °C. This synthetic method, which is related to that previously used to prepare 2,5‐bis(diphenylphosphanylmethyl)pyrrole from 2,5‐bis(dimethylaminomethyl)pyrrole and Ph 2 PH, quantitatively provided HpyrmP t Bu 2 in one step from HpyrmNMe 2 , being therefore much more convenient than alternative but low‐yield methods used to prepare other 2‐phosphanylmethylpyrroles (typically involving a LiAlH 4 reduction of the corresponding pyrrole‐functionalized phosphane oxide, whose preparation requires several steps) or 2,5‐bis(diphenylphosphanylmethyl)pyrrole (by treating a solution of KPPh 2 in DMSO with 2,5‐bis(trimethylammoniomethyl)pyrrole diiodide, which should also be prepared).…”

“…Given the ability of variousd eprotonated 2-phosphanylmethylpyrroles to act as chelating ligandsi nt ransition-metal complexes, [17] we decided to preparet he hitherto unknown phosphane-functionalized pyrrole HpyrmPtBu 2 (Scheme 1) with the aim of using it as ap recursor to aP GeP germylene, because the presence of the tBu 2 Pg roups not only would sterically protect the highly reactive Ge atom butc ould also stabilizet he molecule by alleviating the strong Lewis acidity of the divalent Ge atom through P-Ge interactions, as has been previously shown for the only hitherto reported PGeP germylenes Aa nd B( Figure 1). [11][12][13] We prepared HpyrmPtBu 2 by heating2 -di-methylaminomethylpyrrole (HpyrmNMe 2 )w ith tBu 2 PH in the absence of any solventa t1 35 8C.…”

Nickel(II) Complexes Containing a Pyrrole–Diphosphine Pincer Ligand

“…The preparation of H(P 2 Ph Pyr) (3) proceeded by the addition of 2 equiv of diphenylphosphine to the previously reported pyrrole-2,5-dicarboxaldehyde 47 (Scheme 1) following a procedure adapted from the synthesis of phosphinopyrrole reported by Bochmann et al 45 The resulting phosphine oxide (1) could be prepared on gram scales in satisfactory yield without chromatographic purification. The 31 P NMR spectrum of 1 displays a single resonance at 27.5 ppm in chloroform-d with a J PH = 12 Hz coupling to the protons of the methylene linker.…”

“…Bidentate ligands featuring phosphinopyrroles find precedent in nickel chemistry, suggesting that an analogous pincer-type ligand would be successful in supporting various metal complexes. 45 Furthermore, related diphosphinocarbazole ligands have found use in lanthanide chemistry (scandium, yttrium, and erbium), although the larger bite angle of these systems is likely incompatible with coordination to smaller 3d metals. 46 We therefore sought to prepare a new pincer ligand containing ligating phosphine atoms and a central pyrrole linked by a methylene group, reasoning that the resulting chelate angle would be ideal for transition-metal ions.…”

2-(Diphenylphosphinoylmethyl)pyrrole–2-(diphenylphosphinomethyl)pyrrole (0.43/0.57) and tetrachlorido(5-diphenylphosphinomethyl-2H-pyrrole-κ2N,P)titanium(IV)

“…The combination of an anionic pyrrolate moiety with other donors is, however, less common. In an effort to explore routes to new N,P-and N,Ochelate ligands based on pyrrolates, we have recently introduced the families of pyrrole-phosphine oxide [see (I) in the scheme as an example] and pyrrole-phosphine ligands [see (II) in the scheme as an example] (Broomfield, Boschert et al, 2009;. These ligands are attractive as the nature of the groups on the P atom [phenyl in both (I) and (II)] can be varied at a late stage of the synthesis by appropriate choice of the phosphine starting material.…”