Reappraising Schmidpeter's bis(iminophosphoranyl)phosphides: coordination to transition metals and bonding analysis

Abstract

The synthesis and characterization of a range of bis(iminophosphoranyl)phosphide (BIPP) group 4 and coinage metals complexes is reported. BIPP ligands bind group 4 metals in a pseudo fac-fashion, and the...

Template Synthesis of NPN′ Pincer-type Ligands at Titanium Using an Ambiphilic Phosphide Scaffold

“…The three moieties (phosphide: P1; phosphoranyl: P2; and phosphine: P3) give rise to the well-separated signals (P1: −62 to −67 ppm; P2: 17 to 20 ppm; and P3: −22 to −30 ppm). A large 1 J scalar coupling can be observed between P1 and P2 for 2a–d ( 1 J P1P2 = 330–360 Hz), although it is smaller than that in complex 1 (416 Hz) . Additional small 2 J and 3 J coupling through Ti can be measured for 2a–c ( 2 J P1P3 , 3 J P2P3 ≈ 7 Hz).…”

“…Diatomaceous earth (dicalite) was dried in an oven at 110 °C. Complex 1 and [Et 3 SiHSiEt 3 ]­[B­(C 6 F 5 ) 4 ] were prepared according to the literature procedures. All other reagents were commercially available and used as received.…”

“…BIPP are valence isoelectronic to bis­(iminophosphoranyl)­methanediides (BIPM), which can be considered as P­(V)-stabilized geminal dianions. , However, BIPP can hardly be described as classical phosphide ligands: for instance, in complex 1 (Chart ), the electron-withdrawing effect of the substituents is such that the negatively charged central phosphorus atom only interacts electrostatically with Ti. In fact, the low-lying (−1.61 eV) LUMO of 1 displays P–P antibonding character, which suggests that the central phosphorus atom could be sensitive to nucleophilic attack …”

“…12−14 W e h a v e r e c e n t l y r e p o r t e d t h e u s e of b i s -(iminophosphoranyl)phosphide anions (BIPP) as ligands for transition metals. 23 BIPP are valence isoelectronic to bis-(iminophosphoranyl)methanediides (BIPM), which can be considered as P(V)-stabilized geminal dianions. 24,25 However, BIPP can hardly be described as classical phosphide ligands: for instance, in complex 1 (Chart 3), the electron-withdrawing effect of the substituents is such that the negatively charged central phosphorus atom only interacts electrostatically with Ti.…”

“…In fact, the low-lying (−1.61 eV) LUMO of 1 displays P−P antibonding character, which suggests that the central phosphorus atom could be sensitive to nucleophilic attack. 23 Overall, experimental and computational evidence indicates that BIPP complexes are closely related to ambiphilic triphosphenium (TP) cations, another type of dicoordinate phosphorus compounds. 27−29 This analogy can be understood by considering the depiction of BIPP and TP using the arrow formalism (Chart 4).…”