The transition-metal chemistry of amidinatosilylenes, -germylenes and -stannylenes

• Published in: Coordination chemistry reviews Vol. 300; pp. 1 - 28
• Main Authors: Álvarez-Rodríguez, Lucía, Cabeza, Javier A., García-Álvarez, Pablo, Polo, Diego
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.09.2015
• Subjects: Amidinates; Germylene ligands; Heavier tetrylenes as ligands; Silylene ligands; Stannylene ligands; Transition-metal complexes; dd; py; Silylene ligands; HT; tBuAdbzam; Cp; iPr2bzam; dt; Diip2dmaam; dmpe; Amidinates; ref; DFT; pin; Ph; NBO; tmeda; Stannylene ligands; e.g; OTf; TBP; quint; MS; IR; RcBrH2; Diip; EttBubzam; nbd; Hz; iPr2Diiaam; 1H; Me; vs; vw; RT; Ad; C; Å; PSQP; HOMO; LUMO; NHC; I; iPr; Diip2tbam; L; M; Et; Me2acam; TMS2bzam; br; tol; Ar; THF; sh; tBu2bzam; DMAP; RcH3; Fc; tBuDiipdmaam; d; Heavier tetrylenes as ligands; tBu; cm; Transition-metal complexes; ppm; tBuDiipbzam; NMR; s; t; Germylene ligands; HMDS; w; coe; cod; dma; TM; TMS; dme
• ISSN: 0010-8545; 1873-3840
• DOI: 10.1016/j.ccr.2015.04.008

•The synthesis, reactivity and catalytic activity of transition-metal derivatives of heavier tetrylene amidinates (amidinato-HT–TM complexes) are reviewed.•Most of the hitherto reported amidinato-HT–TM complexes are silylene or germylene derivatives.•Amidinato-HTs are strong electron-donating ligands, stronger than N-heterocyclic carbenes (NHCs) in many cases.•The electronic and steric properties of amidinato-HTs can be easily tuned. The transition-metal (TM) chemistry of heavier tetrylenes (HTs), also known as heavier carbene analogs, group 14 metalenes or group 14 metalylenes (compounds containing Si, Ge, Sn or Pb in +2 oxidation state), has experienced an exponential growth in the last few years because new families of HTs have emerged to the main-group chemistry arena. One of these families is characterized by the presence of an amidinato group attached to the group 14 element. Although the first report dealing with amidinato-HT–TM complexes appeared only seven years ago, nearly one hundred TM complexes containing amidinato-HT ligands are currently known and, remarkably, some of them have already been recognized as catalyst precursors for useful transformations of organic substrates (Sonogashira, Kumada and Negishi cross-couplings, ketone hydrosilylations, cycloadditions, arene C–H borylations, etc.). Thus, amidinato-HTs have emerged as promising alternatives to widely used classical ligands, such as phosphines or N-heterocyclic carbenes. This review comprehensively surveys the TM chemistry of amidinato-HTs published up to the end of 2014, examining not only the synthesis and characterization of these complexes, but paying special attention to reactivity studies, theoretical investigations and catalytic applications.