Reductive Reactivity of the 4f5d Gd(II) Ion in {Gd[N(SiMe)]}: Structural Characterization of Products of Coupling, Bond Cleavage, Insertion, and Radical Reactions.

The reductive reactivity of a Ln(II) ion with a nontraditional 4f5d electron configuration has been investigated by studying reactions of the {Gd(N(SiMe))]} anion with a variety of reagents that survey the many reaction pathways available to this ion. The chemistry of both [K(18-c-6)] and [K(crypt)] salts (18-c-6 = 18-crown-6; crypt = 2.2.2-cryptand) was examined to study the effect of the countercation. CS reacts with the crown salt [K(18-c-6)][Gd(NR)] () to generate the bimetallic (CS) complex {K(18-c-6)Gd(NR)]}, which contains two trithiocarbonate dianions that bridge Gd(III) centers and a potassium ion coordinated by 18-c-6. In contrast, the only crystalline product isolated from the reaction of CS with the crypt salt [K(crypt)][Gd(NR)] () is [K(crypt)]{(RN)Gd[SCS(CH)Si(Me)N(SiMe)-κ,κ]}, which has a CS unit inserted into a cyclometalated amide ligand. Complexes and reductively couple pyridine to form bridging dipyridyl moieties, (NCH-CHN), that generate bimetallic complexes differing only in the countercation, {[K(18-c-6)(CHN)]}{[(RN)Gd][μ-(NCH-CHN)]} and [K(crypt)]{[(RN)Gd][μ-(NCH-CHN)]}. Complexes and also show similar reactivity with (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) to form the (TEMPO) complexes [K(18-c-6)][(RN)Gd(η-ONCHMe)] and [K(crypt)][(RN)Gd(η-ONCHMe)], respectively. The first example of a bimetallic coordination complex containing a Bi-Gd bond, [K(crypt)][(RN)Gd(BiPh)], was obtained by treating with BiPh.