Ge=B‐π‐Bindung: Synthese und reversible [2+2]‐Cycloaddition von Germaborenen

Phosphine-Stabilized Pnictinidenes

The reaction of the intramolecular germylene‐phosphine Lewis pair (o‐PPh₂)C₆H₄GeAr* (1) with Group 15 element trichlorides ECl₃ (E=P, As, Sb) was investigated. After oxidative addition, the resulting compounds (o‐PPh₂)C₆H₄(Ar*)Ge(Cl)ECl₂ (2: E=P, 3: E=As, 4: E=Sb) were reduced by using sodium metal or LiHBEt₃. The molecular structures of the phosphine‐stabilized phosphinidene (o‐PPh₂)C₆H₄(Ar*)Ge(Cl)P (5), arsinidene (o‐PPh₂)C₆H₄(Ar*)Ge(Cl)As (6) and stibinidene (o‐PPh₂)C₆H₄(Ar*)Ge(Cl)Sb (7) are presented; they feature a two‐coordinate low‐valent Group 15 element. After chloride abstraction, a cyclic germaphosphene [(o‐PPh₂)C₆H₄(Ar*)GeP] [B(C₆H₃(CF₃)₂)₄] (8) was isolated. The ³¹P NMR data of the germaphosphene were compared with literature examples and analyzed by quantum chemical calculations. The phosphinidene was treated with [iBu₂AlH]₂, and the product of an Al−H addition to the low‐valent phosphorus atom (o‐PPh₂)C₆H₄(Ar*)Ge(H)P(H)Al(C₄H₉)₂ (9) was characterized.

Germaborenes: Borylene Transfer Agents for the Synthesis of Iminoboranes

Halide and phenyl substituted germaborenes were shown to react with azides at room temperature and transfer a borylene moiety to give iminoboranes. This iminoborane synthesis based on a borylene transfer route was investigated computationally in the case of the phenyl substituted germaborene.

Structural Snapshots of π-Arene Bonding in a Gold Germylene Cation

Heavier group 14 element cations exhibit a remarkable reactivity that has typically hampered their isolation. For the few available examples, the role of π‐arene interactions is crucial to provide kinetic stabilization, but dynamic and structural information on those contacts is yet limited. In this study we have accessed the metalogermylenium cation [(PMe₂Ar^Dipp2)AuGe(Ar^Dipp2)Cl]⁺ (4⁺) (Ar^Dipp2=C₆H₃‐2,6‐(C₆H₃‐2,6‐iPr₂)₂) that has been structurally characterized with three different non‐coordinating counter anions. These studies provide for the first time dynamic information about the conformational rearrangement that characterizes π‐arene bonding thorough a series of X‐ray diffraction structural snapshots. Computational studies reveal the weak character of the π‐arene bonding (ca. 2 kcal mol⁻¹) that can be described as the donation from a π_C=C bond toward the empty p valence orbital of germanium.

Bonding Relationship between Silicon and Germanium with Group 13 and Heavier Elements of Groups 14-16

The topic of heavier main group compounds possessing multiple bonds is the subject of momentous interest in modern organometallic chemistry. Importantly, there is an excitement involving the discovery of unprecedented compounds with unique bonding modes. The research in this area is still expanding, particularly the reactivity aspects of these compounds. This article aims to describe the overall developments reported on the stable derivatives of silicon and germanium involved in multiple bond formation with other group 13, and heavier groups 14, 15, and 16 elements. The synthetic strategies, structural features, and their reactivity towards different nucleophiles, unsaturated organic substrates, and in small molecule activation are discussed. Further, their physical and chemical properties are described based on their spectroscopic and theoretical studies.