Several new cobalt(iii) complexes containing (3-aminopropyl) dimethylphosphine (pdmp) have been prepared, and their molecular structures have been determined. A dichloro complex of trans(Cl,Cl)-cis(P,P)-[CoCl 2(pdmp)2]PF6 (1) was prepared from trans-[CoCl2(py)4]Cl·6H2O and pdmp. X-Ray crystallography confirmed the (C2)-chair2 conformation of two six-membered pdmp chelate rings in 1, while the analogous 1,3-bis(dimethylphosphino)propane (dmpp) complex trans-[CoCl2(dmpp) 2]ClO4 (3) exhibited the (D2d)-twist 2 conformation. Substitution reactions of 1 for ethane-1,2-diamine (en), pentane-2,4-dionate (acac), and N,N-dimethyldithiocarbamate (dtc) gave the mixed-ligand tris(chelate)-type complexes of [Co(en)2(pdmp)]Cl 2(PF6) (5), [Co(acac)(pdmp)2](PF 6)2 (7), and [Co(dtc)3-n(pdmp) n](PF6)n [n = 1 (9) or 2 (10)], respectively. The conformer of the complex cation in 5 was assigned as lel·ob· chair by X-ray analysis. In the case of the acac complex 7, both trans(P,N) (7a) and trans(N,N) (7b) isomers were isolated, and the complex cations were characterized as syn-chair2 and anti-chair2 conformers, respectively, with respect to the six-membered pdmp chelate rings. These conformers coincide with the most stable ones anticipated by the DFT optimum geometry calculations. In the crystal structure of trans(P,N)-[Co(dtc)(pdmp) 2](BPh4)2 (10′) one of the pdmp chelate rings adopted a skew-boat (twist) conformation, which reduced the intramolecular steric ring-ring interaction effectively. The DFT optimized geometries for several isomers and/or conformers of [CoCl2(pdmp)2] + were compared.
ASJC Scopus subject areas
- Inorganic Chemistry