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

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 tBuLi 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)­OiPr} (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.