Synthesis and Reaction Chemistry of Divalent Metal Complexes Derived from Bulky Guanidinate Ligands

The present research work is focused on the chemistry of late transition metal complexes derived from monoanionic guanidinate ligands [(RN)C(NHPr i)(NPri)]. [R = 2,6.Me 2C6H3 (HGua--), 2.PPh 2C6H4 (HPGua--)] and [(2,6.C 6H3Pri 2N) 2C(NEt2)]-- (LGua.), and dianionic guanidinate ligands [(RN)C(NPri)2]2-- [R = 2,6.Me2C6H3 (Gua2--), 2.PPh2C6H4 (PGua2--)].;Chapter 2 deals with the coordination chemistry of the HGua-- ligand with Fe(II), Co(II), Rh(I), Cu(I) and Ag(I) ions. In addition, the reaction chemistry of [Fe(HGua)2] (2.3) and [Co(HGua)2] (2.4) has been examined in our work. Oxidation of Fe(II) complex 2.3 with AgCl, Br2, I2, PhEEPh (E = S, Se), Se, AgBF4 and AgN3 gave the corresponding bis(guanidinato) Fe(III) complexes [Fe(HGua)2X] [X = F (2.15), Cl ( 2.8), Br (2.9), I (2.10)], [Fe(HGua)2(EPh)] [E = S (2.11), Se (2.12)], [{Fe(HGua)2}2(mu--Se)] (2.13) and [Fe(HGua)2N3] (2.16). On the other hand, reactions of complex [Co(HGua)2] (2.4) with I 2/tmeda (tmeda = N,N,N',N'--tetramethylethylenediamine) and excess sulphur led to [Co(HGua)I(tmeda)] (2.17) and [Co(HSGua) 2] (2.18) [HSGua-- = (2,6.Me2 C6H3N)C(NHPri)(SNPr i).], respectively.;Chapter 3 is devoted to the preparation and reaction chemistry of a Co(I) guanidinate complex. Treatment of lithium guanidinates [Li(HPGua)]2 (3.1) and [Li(LGua)(tmeda)] (3.2) with appropriate halide salts of Fe(II) and Co(II) afforded a series of Fe(II) and Co(II) guanidinate complexes, namely [Fe(HPGua)2] (3.3), [Co(HPGua) 2] (3.4), [Co(HPGua)X]2 [X = Cl (3.5), I (3.7)], [Co(HPGua)Br]2•CoBr2 (3.6•CoBr 2) and [M(LGua)Cl(tmeda)] [M = Fe (3.8), Co (3.9 )]. Reduction of complex [Co(LGua)Cl(tmeda)] (3.9) with potassium metal in toluene at room temperature gave [Co(LGua)(PhMe)] ( 3.10). The reaction chemistry of complex 3.10 has also been examined. This includes its reactions with Lewis bases (PMe3, dimethylaminopyridine, ButNC), PhNNPh, Me 3SiCCSiMe3, and Ag(I) salts (AgF, AgN3).;Chapter 4 covers the synthesis and structural characterization of Mg(II) complexes supported by monoanionic HGua-- and HPGua -- ligands as well as dianionic Gua2-- and PGua2-- ligands. Mg(II) guanidinate complexes [Mg(HGua) 2(THF)] (4.3) and [Mg(HPGua)2] (4.4) were prepared by the reactions of [K(HGua)(PhMe)0.5]infinity with MgI2, and H2PGua with MgBu n2, respectively. On the other hand, treatment of H2Gua or H2PGua with appropriate Grignard's reagents led to the formation of [Mg4(Gua)2I2(mu--I) 2(Et2O)2] (4.5), [Mg2(PGua)I 2(Et2O)2].Et2O (4.6.Et 2O), [Mg3(Gua)X2(mu--X)2(THF) 4] [X = Br (4.7), Cl (4.8)] and [Mg 2(PGua)Br(mu--Br)(THF)3]2 (4.9). Complexes 4.5--4.9 represent the first examples of magnesium complexes bearing dianionic guanidinate ligands.;Chapter 1 gives an overview on the chemistry of metal guanidinate complexes. Their preparation, properties as well as applications were covered in this chapter.;Finally, a summary of findings of this research work and its future direction is presented in Chapter 5.