Preparation, Characterization, and Theoretical Analysis of Group 14 Element(I) Dimers: A Case Study of Magnesium(I) Compounds as Reducing Agents in Inorganic Synthesis

A synthetic route to the new amidine (DipNH) (DipN) C (C (6) H (4) Bu (t) -4) (ButisoH; Dip = C (6) H (3) Pr (i) (2) -2, 6) has been developed. Its deprotonation with either LiBu (n) or KN (SiMe (3) ) (2) yields the amidinate complexes M (Butiso) (M = Li or K). Their reactions with group 14 element halides/pseudohalides afford the heteroleptic group 14 complexes (Butiso) SiCl (3), (Butiso) ECl (E = Ge or Sn), and (Butiso) Pb (μ-O (3) SCF (3) ) (THF) (∞), all of which have been crystallographically characterized. In addition, the synthesis and spectroscopic characterization of the homoleptic complex Pb (Butiso) (2) is reported. Reductions of the heteroleptic complexes with a soluble magnesium (I) dimer, ( (Mes) Nacnac) Mg (2) ( (Mes) Nacnac = (MesNCMe) (2) CH (-) ; Mes = mesityl), have given moderate-to-high yields of the group 14 element (I) dimers (Butiso) E (2) (E = Si, Ge, or Sn), the X-ray crystallographic studies of which reveal trans-bent structures. The corresponding lead (I) complex could not be prepared. Comprehensive spectroscopic and theoretical analyses of (Butiso) E (2) have allowed their properties to be compared. All complexes possess E-E single bonds and can be considered as intramolecularly base-stabilized examples of ditetrelynes, REER. Taken as a whole, this study highlights the synthetic utility of soluble and easy to prepare magnesium (I) dimers as valuable alternatives to the harsh, and often insoluble, alkali-metal reducing agents that are currently widely employed in the synthesis of low-oxidation-state organometallic/inorganic complexes.