Tri(pyridylmethyl)phosphine: The Elusive Congener of TPA Shows Surprisingly Different Coordination Behavior

Abstract

Tri(pyridylmethyl)phosphine (TPPh), the remarkably elusive congener of tri(pyridylmethyl)amine (TPA), has been prepared, as well as the relative tri(N-methyl-pyridylamino)phosphine (TPAMP). The coordination properties of these new ligands have been evaluated for chromium(III), iron(II), and ruthenium(II) complexes and compared with the related TPA complexes. In all cases, a different coordination behavior has been observed whereby TPPh and TPAMP always act as tridentate ligands. A chromium(III) complex [Cr(TPPh)Cl3] has been prepared, which has shown low ethylene oligomerization activity. Octahedral low spin iron(II) complexes [Fe(TPPh)2](2+) and [Fe(TPAMP)2](2+) were obtained with two ligands bound to the metal center. Ruthenium(II) chloro complexes of TPA and TPPh undergo ligand exchange reactions in acetonitrile, and the ruthenium(II) complex [Ru(MeCN)2(TPA)](2+) can be oxidized by m-CPBA in acetonitrile to give a transient ruthenium(IV) oxo complex [Ru(O)(MeCN)(TPA)](2+). Attempts to generate high valent ruthenium(IV) oxo TPPh or TPAMP complexes could not be achieved, probably due to insufficient stabilization by these strong field ligands.

Solid-Phase Synthesis as a Platform for the Discovery of New Ruthenium Complexes for Efficient Release of Photocaged Ligands with Visible Light

“…Compound 8a , a derivative of TPA, was used to develop the protocol because data for ruthenium(II) TPA complexes were available to use as benchmarks. 49,67,68 Two ruthenium(II) starting materials were surveyed initially, cis -[Ru(DMSO) 4 Cl 2 ], which was expected to give a mixture of complexes of the general formula [Ru( 8a )(DMSO)Cl] + that could later be converted into [Ru( 8a )(MeCN) 2 ] 2+ , and [Ru(COD)(MeCN) 4 ](OTf) 2 , 69 which could potentially give access to the desired complex [Ru( 8a )(MeCN) 2 ] 2+ directly in one step. Combining resin-bound 8a with 2–10 equiv.…”

Ruthenium Tris(2-pyridylmethyl)amine as an Effective Photocaging Group for Nitriles

“…The structural parameters for 1 are similar to those reported recently for [Ru(TPA)(MeCN) 2 ](SbF 6 ) 2 . 12 …”

Architecture and synthesis of P,N-heterocyclic phosphine ligands

“…Thus, when reacting P(SiMe 3 ) 3 with 3 equivalents of 2-picolyl chloride (34) in DCM ligand 35 was obtained in low yield (33% based on 34). Alternatively, when 3 equivalents of 2-(trimethylsilylmethyl)pyridine (36) with an equivalent of phosphorous trichloride were reacted, compound 37 was obtained with relatively good yield of about 76% (based on PCl 3 , Scheme 6) [67]. The byproduct Me 3 SiCl can be easily be removed by distillation or in vacuo.…”