Download or read book The Coordination Chemistry of Thioether-supported, Low-valent Cobalt Complexes written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The tridentate S3- donor ligand, phenyltris((tert-butylthio)methyl)borate, [PhTttBu]-, has been used to investigate the coordination chemistry of cobalt. A series of coordinatively and electronically unsaturated organocobalt(II) complexes [PhTttBu]Co(R) (R = CH3, CH2CH3, C6H5, CH2C6H5, C3H5) was synthesized through reaction of the starting material [PhTttBu]COCl, with the appropriate Grignard reagent. The resultant pseudotetrahedral complexes (allyl derivative is square pyramidal) proved to be both air and moisture sensitive. The complexes were characterized spectroscopically and crystal lographically. The small molecule reactivity of these complexes was assayed through reactions with CO and NO. The former reagent showed sensitivity to the identity of the organocobalt while the latter gave rise to the same product, regardless of the organic ligand. When R = CH3, CH2CH 3, C6H5, reaction of [PhTttBu]Co(R) with CO yielded red, five-coordinate [PhTttBu]Co(CO)(C(O)R). These square-pyramidal complexes contain apical thioether ligation with the remaining four ligands in the basal plane. Alternatively, when R = CH 2C6H5, C3H5, reaction with CO resulted in Co-C bond homolysis with formation of the brown Co(I) complex, [PhTtBu]Co(CO)2. In all cases, reaction of the organocobalt(II) complexes with NO resulted in the formation of the & kappa;2-dinitrosyl complex, [& kappa;2-PhTttBu]Co(NO)2. These results were confirmed both spectroscopically and crystallographically. A series of cobalt(I) phosphine complexes, [PhTttBu ]Co(PR3), PR3 = PMe3, PEt3, PMe2Ph, PMePh2, PPh3, P(OPh3), was prepared by reduction of [PhTttBu]COCl in the presence of the phosphine. These four-coordinate complexes were characterized spectroscopically and crystal lographically. The structures may be grouped into two classes, pseudo-tetrahedral and cis-divacant (i.e. an octahedron where two cis ligands have been removed, & alpha; = 54.7° for this complex; a & alpha; is the degree to which L lies off of the linear vector). The former class, for which PR 3 = PMe3, PEt3, PMe2Ph, the phosphine donor resides approximately on the B ... Co vector. The latter class, for which PR3 = PMePh2, PPh3, P(OPh) 3, the phosphine is significantly 'off-axis.' These complexes exhibited varying a angles allowing for insight into the structural choice of the complex based on the & sigma;-donating and & pi;-accepting properties of the phosphine donor. The cobalt and nickel isocyanide complexes, [PhTttBu]M(CNBu t) are readily alkylated with MeI, leading to the corresponding cationic iminoacyl complexes, [[PhTttBu]M(C(Me)NBut)]I.