Syntheses of phosphiranes, unsymmetrical diphosphines and oligomeric polyphosphines. Insights into these ligands, phosphino-phosphinine and 2,2\u27-biphosphinine coordination chemistry

A synthesis of phosphiranes is reported. Bulky substituents at the phosphorus center were proven to stabilize these ligands. The lone pair at the phosphorus was shown by NMR studies of phosphirane-transition metal complexes (8-10) to possesses a large s character. An X-Ray crystal study of complex 7 provided structural information. Synthesis of various complexes of 2-diphenylphosphino-3-methylphosphinine (dppmpn) was performed. The first reported gold (I) complex, 13 and a X-Ray crystal and electrochemical studies of a Ni(0) dimer, 14, revealed interesting features resulting from the presence of the ligand. Synthesis of a Pt(II) complex of $4,4\sp\prime ,5,5\sp\prime$-tetramethyl-2,$2\sp\prime$-biphosphinine (tmbp) confirmed the high reactivity of this strong $\pi$-accepting ligand toward electrophilic transition metal centers. On the other hand, a Cu(I)-(tmbp)-dithiolene complex, 16, was shown to possess unprecedented structural features. A rational synthesis of polyphosphines in which phosphorus centers are separated by one methylene unit was developed, and a new triphosphine monooxide, 29, a tetraphosphine, 33, and a pentaphosphine, 34, are reported. The simple method also allows for the easy acess to unsymmetrical, chiral, racemic diphosphines, 22-24 and 28, or phosphine-phosphinite, 26, and diastereomeric phosphine-phosphinite, 27. Separation of diastereomeric compounds of 33 and 34 were attempted via borane complexation and transition metal complex formation. Crystallization of a Pd-tetraphosphine complex, 48, and a X-Ray crystal study provided structural information on the new ligand 34. The phosphine-phosphinite (27)/Pd(II) diastereomeric complexes, 63a and 63b, were partially separated by selective precipitation, and one complex was shown to react with water to form a bimetallic complex, 64, which has been structurally characterized