Mono- and binuclear complexes of rhodium involving a new series of hemilabile o-phosphinoaniline ligands

Abstract

Monophosphines of the type Ph(x)PAr(3-x) (x = 0, 1 or 2, Ar = o-N-methylanilinyl) and the diphosphine, Ar(2)PCH(2)PAr(2) (mapm) have been synthesized for use as chelating and/or bridging P,N-ligands within mono- and binuclear rhodium(i) complexes, respectively. The previously prepared phosphines, Ph(x)PAr'(3-x) (x = 0, 1 or 2, Ar' = o-N,N-dimethylanilinyl) and Ar'(2)PCH(2)PAr'(2) (dmapm), have also been used to prepare analogous mono- and binuclear complexes. Variable temperature (1)H NMR spectroscopy of the mononuclear complexes, [RhCl(CO)(L)] (L = PhPAr(2), PhPAr'(2), PAr(3) and PAr'(3)), and line-shape analyses of the resultant spectra indicate the substantially increased lability of the N,N-dimethylanilinyl donors relative to the related monomethylanilinyl groups. X-Ray structural analyses of the mononuclear complexes suggest that the enhanced Type II hemilability in the dimethylanilinyl complexes compared to their monomethyl analogues results from increased steric interactions involving the coordinated dimethylanilinyl substituents. In the case of the binuclear, dmapm-bridged compound [Rh(2)Cl(2)(CO)(2)(micro-dmapm)], there are additional transannular repulsions between the chloro ligand on one metal and the coordinated dimethylanilinyl group on the other, which result in a Rh-Rh separation of over 4.1 A. For the analogous mapm-bridged species, the transannular interactions between the chloro ligands and the amine hydrogens are in fact attractive, resulting in a much closer Rh-Rh separation (3.450 A). The chloride substituents of [Rh(2)Cl(2)(CO)(2)(micro-mapm)] can be replaced to generate the complexes, [Rh(2)(X)(2)(CO)(2)(micro-mapm)] (X = I, CF(3)SO(3), CH(3)CO(2)), the last of which also exhibits pronounced transannular hydrogen-bonding interactions in the solid state.

Phosphorus as a Lewis Acid: CO2 Sequestration with Amidophosphoranes

“…Reaction of the o ‐phosphinoaniline Ph 2 P( o ‐C 6 H 4 NHMe)10 with XeF 2 11 at −35 °C in CH 2 Cl 2 produces the off‐white difluorophosphorane, Ph 2 PF 2 ( o ‐C 6 H 4 NHMe), 1 (Scheme ). The 31 P{ 1 H} NMR spectrum of 1 reveals a high‐field triplet at δ =−45.6 ppm ( 1 J PF =625 Hz), while the 1 H NMR spectrum depicts the NH resonance as a broad quartet at δ =4.68 ppm ( 3 J HH =5.0 Hz) that couples to the N ‐methyl signal at δ =2.67 ppm.…”

Phosphorus as a Lewis Acid: CO2 Sequestration with Amidophosphoranes

“…In this regard, the use of metal-free, frustrated Lewis pairs (FLPs) has received recent attention. These species serve as hypothetical intermediates for the generation of ring-strained amidophosphoranes, which are shown to sequester CO 2 .Reaction of the o-phosphinoaniline Ph 2 P(o-C 6 H 4 NHMe) [10] with XeF 2[11] at À35 8C in CH 2 Cl 2 produces the off-white difluorophosphorane, Ph 2 PF 2 (o-C 6 H 4 NHMe), 1 (Scheme 1). [3] Subsequent work by the groups of OHare [4] and Piers, [5] as well as ourselves, [6] has demonstrated the use of B/P, B/N, and Al/P-based FLPs for the conversion of CO 2 into methanol, methane, or CO.…”

“…Herein, we describe the syntheses of aminophosphonium salts, which incorporate Lewis basic and acidic pnictogen functionalities within an intramolecular system. These species serve as hypothetical intermediates for the generation of ring-strained amidophosphoranes, which are shown to sequester CO 2 .Reaction of the o-phosphinoaniline Ph 2 P(o-C 6 H 4 NHMe) [10] with XeF 2[11] at À35 8C in CH 2 Cl 2 produces the off-white difluorophosphorane, Ph 2 PF 2 (o-C 6 H 4 NHMe), 1 (Scheme 1). The 31 P{ 1 H} NMR spectrum of 1 reveals a highfield triplet at d = À45.6 ppm ( 1 J PF = 625 Hz), while the 1 H NMR spectrum depicts the NH resonance as a broad quartet at d = 4.68 ppm ( 3 J HH = 5.0 Hz) that couples to the N-methyl signal at d = 2.67 ppm.…”

“…Reaction of the o-phosphinoaniline Ph 2 P(o-C 6 H 4 NHMe) [10] with XeF 2 [11] at À35 8C in CH 2 Cl 2 produces the off-white difluorophosphorane, Ph 2 PF 2 (o-C 6 H 4 NHMe), 1 (Scheme 1). The 31 P{ 1 H} NMR spectrum of 1 reveals a highfield triplet at d = À45.6 ppm ( 1 J PF = 625 Hz), while the 1 H NMR spectrum depicts the NH resonance as a broad quartet at d = 4.68 ppm ( 3 J HH = 5.0 Hz) that couples to the N-methyl signal at d = 2.67 ppm.…”

Dinuclear copper complexes: coordination of Group 14 heteroborates

“…[54][55][56][57] The palladium, platinum, rhodium, iridium and ruthenium coordination chemistry of this hexadentate ligand was studied successfully. [55][56][57][58][59][60][61] Treatment of the dmapm ligand with two equivalents of the copper electrophile [Cu(CH 3 CN) 4 ][BF 4 ] (Scheme 1) leads to the formation of the dinuclear copper complex 1. The bisacetonitrile adduct 1 was isolated in high yield and was characterized by NMR spectroscopy, elemental analysis and single crystal structure analysis.…”