Synthesis and Reactions of the First Room Temperature Stable Li/Cl Phosphinidenoid Complex

Abstract

P-Trityl substituted Li/Cl phosphinidenoid tungsten(0) complex (OC)5W{Ph3CP(Li/12-crown-4)Cl} (3) was prepared via chlorine/lithium exchange in complex (OC)5W{Ph3CPCl2} (2) using (t)BuLi in the presence of 12-crown-4 in tetrahydrofuran (THF) at low temperature; complex 3 possesses significantly increased thermal stability in contrast to previously reported analogue derivatives. Terminal phosphinidene-like reactivity of 3 was used in reactions with benzaldehyde and isopropyl alcohol as oxaphosphirane complex (OC)5W{Ph3CPC(Ph)O} (5) and phosphinite complex (OC)5W{Ph3CP(H)O(i)Pr} (6) were obtained selectively. Reaction of 3 with phosgene allowed to obtain the first kinetically stabilized chloroformylphosphane complex (OC)5W{Ph3CP(Cl)C(O)Cl} (4). Density functional theory (DFT) calculations revealed remarkable differences in the degree of P-Li bond dissociation 3a-d: using a continuum model 3 displays a covalent character of P-Li bond (COSMO (THF)) (a), which becomes elongated if 12-crown-4 is coordinated to lithium (b) and is cleaved if a dimethylether unit is additionally coordinated to lithium (c). A similar result was obtained for the case of 3(thf)4 in which also a solvent-separated ion pair structure is present (d). All products were unambiguously characterized by various spectroscopic means and, in the case of 2 and 4-6, by single-crystal X-ray diffraction analysis. In all structures very long P-C bonds were determined being in the range from 1.896 to 1.955 Å.

Synthesis and Deprotonation of Aminophosphane Complexes: First K/N(H)R Phosphinidenoid Complexes and Access to a Complex with a P2N‐Ring Ligand

“…Both complexes show similar P−W bond lengths compared to the analogous P−CH(SiMe 3 ) 2 ‐substituted aminophosphane complexes, whereas significant bond elongation was observed for the P−C bond: 1.918(2) ( 3 c ) and 1.897(3) Å ( 3 e ) versus 1.835(13) Å . The bond elongation in the former cases is presumably due to the repulsive interaction induced by the bulky triphenylmethyl group and has reportedly been a feature of all trityl‐substituted phosphane complexes . The N−C bond length in complex 3 e (1.497(3) Å) is slightly longer than in complex 3 c (1.405(3) Å).…”

“…The 31 P NMR resonances of the K/NHR phosphinidenoid complexes 4 c ( δ =90.6 ppm, 1 J P,W =98.3 Hz) and 4 e ( δ =91.1 ppm, 1 J P,W =100.2 Hz) were observed at lower field compared with their precursors ( 3 c : δ =37.2 ppm, 1 J P,W =263.8 Hz; 3 e : δ =54.6 ppm, 1 J P,W =264.5 Hz), but they were significantly high‐field‐shifted compared with the related Li/Cl and Li/OMe phosphinidenoid complexes (R=CPh 3 : δ =252.0 and 289.5 ppm, 1 J P,W =77.6 and 84.0 Hz, respectively). Both phosphinidenoid complexes 4 c and e displayed significantly larger 1 J P,C coupling constant magnitudes compared with complexes 3 c and e (61.6 and 52.9 Hz vs. 7.1 and 12.5 Hz, respectively).…”

“…Li/Cl phosphinidenoid complex 2 , generated in situ from dichloro(organo)phosphane complex 1 by chlorine/lithium exchange with t BuLi in the presence of 12‐crown‐4, was treated with a series of primary amines at low temperature to selectively yield 1,1’‐bifunctional aminophosphane complexes 3 a – e (Scheme ). All complexes were firmly established by using various spectroscopic and spectrometric methods.…”

“…The stability of such Li/X phosphinidenoid complexes is highly dependent on the organic substituent at the phosphorus center. For example, the trityl Li/Cl phosphinidenoid complex (R=CPh 3 ) was found to be stable at ambient temperature for several hours . Despite detailed solution‐state NMR studies on a series of Li/X phosphinidenoid tungsten(0) complexes (X=F, Cl, Br, I), the isolation was difficult, and only one single‐crystal X‐ray structure has been reported so far .…”

A Novel N,P,C Cage Complex Formed by Rearrangement of a Tricyclic Phosphirane Complex: On the Importance of Non‐covalent Interactions

“…When P ‐CPh 3 phosphinidenoid complex 2 , prepared by chloro/lithium exchange of dichlorophosphane complex 1 with t BuLi in the presence of [12]crown‐4 at −78 °C,22 reacted in situ with dimethylcyanamide, the novel tricyclic phosphane complex 4 was selectively obtained in 45 min at ambient temperature (Scheme ). Here, the intermediacy and intramolecular cycloaddition of the 1,3‐dipole complex 3 can be inferred.…”