Simple basic ingredients are at the origin of the synthesis of Na(OCP), the phosphorus analogue of sodium cyanate. Na(OCP) is obtained from NaPH2 (made from Na, P, and a proton source) and CO (from carbon and air). This salt is remarkably stable, in complete contrast to HCP discovered 50 years ago.

Phosphorus-containing heterocycles have evolved from laboratory curiosities to functional components, such as ligands in catalytically active metal complexes or molecular constituents in electronic devices. The straightforward synthesis of functionalized heterocycles on a larger scale remains a challenge. Herein, we report the use of the phosphaethynolate (OCP)(-) anion as a building block for various sterically unprotected and functionalized hydroxy substituted phosphorus heterocycles. Because the resulting heterocycles are themselves anions, they are building blocks in their own right and allow further facile functionalization. This property may be of interest in coordination chemistry and material science.

We report a series of arylpalladium complexes of acetamidate, sulfonamidate, and deprotonated oxazolidinone ligands that undergo reductive elimination with rates and yields that depend on the binding mode of the ancillary and amidate ligands. Complexes of the acetamidate ligands containing the bidentate phosphines DPPF and Xantphos as ancillary ligands undergo reductive elimination. The rate and yield were higher from the complex ligated by Xantphos, which contains a larger bite angle. In contrast, the analogous amidate complex containing a single sterically hindered monodentate ligand and a kappa2-bound amidate ligand does not undergo reductive elimination. This trend of faster reductive elimination from complexes containing bidentate ancillary ligands than from a complex with a single monodentate ancillary ligand is unusual and is consistent with an effect of the denticity of the ancillary ligand on the binding mode of the amidate. Complexes of sulfonamidate ligands underwent reductive elimination faster than complexes of acetamidates, and reductive elimination occurred from complexes containing both bidentate and monodentate ancillary ligands. Like reductive elimination from the acetamidate complexes, reductive eliminations from the sulfonamidate complexes were faster when the complexes possessed bidentate Xantphos and kappa1-sulfonamidate ligands.

As compared to the normal η1-P σ-complexes or η6-phosphinine π-complexes, the rare μ2-P bridging binding mode of phosphinines can be tuned by employing electron donating substitute.

Electromers are species with significantly different electronic but only slightly different geometrical structures, whereby each species corresponds to a local minimum on the energy hypersurface.[1a-c] Although they have been discussed several times in the literature, direct observation of "electroisomers"-the synonyms "redox isomers" or "valence isomers" are likewise used-is rare.[2] Paramagnetic transition-metal complexes are ideally suited to the study of this phenomenon, and the localization of the spin on either the metal MC(L) or the ligand M + (LC À ) can be characterized by EPR spectroscopy.[3] We report herein a striking example in which two electromers of paramagnetic rhodium complexes coexist in a rapid equilibrium and the distortion of only one P À Rh À P angle results in a substantial redistribution of the spin density.We previously reported paramagnetic [M(troppcomplexes (Scheme 1; M = Rh, Ir), [4a-d] which exist as rapidly exchanging trans/cis mixtures (k isom % 1 10 4 s À1 ) in solution. Both isomers have tetrahedrally distorted structures and their EPR spectra and consequently electronic structures are quite similar. They are best described as strongly delocalized organometallic radicals with less than 30 % of the spin density localized on the metal centers.[4e] We have now synthesized the rhodium complexes 5 a,b, which likewise contain two olefin and two phosphane binding sites in mutual trans positions, but the constraints within the ligand system do not allow trans to cis isomerization. [5] enhances significantly the solubility of 5 b (in diethyl ether, THF, or toluene). The structures of the ligand 2 and complex 5 a are shown in Figure 1. [6a,b] The rigid tripodal diolefin phosphane 2 is preorganized for binding a transition-metal ion in its cleft. Only a small rotation around the PÀC trop bonds is necessary to convert 2 into the conformation it adopts in 5 a, explaining the high stability of this complex. As observed with the related amino ligand trop 2 NH, [7] 5 a shows a distorted "sawhorse" (SH) type structure (a trigonal bipyramid with one missing edge in the equatorial plane): [8] the P1ÀRhÀP2 angle is 160.98 and the ctÀRh1Àct angle is 134.88 (ct = centroid of the coordinated C=C trop bond). The NMR data for all these complexes indicate that C s -symmetrical SH-type structures are retained in solution and that there are no significant cation anion interactions ( 31 P nuclei in trans positions, inequivalent olefinic protons, superimposable data for 5 a and 5 b).A cyclic voltammogram of 5 a in THF/1m nBu 4 N + PF 6 À shows two reversible waves at E 1 8 = À1.339 V and E 2 8 = Scheme 1. Synthesis of trop 2 PPh (2) and the Rh complexes 5 a and 5 b.