The chemistry of transition metal–germanium compounds. Part 2. Synthesis, characterization, structure and reactivity of transition-metal carbonyl-substituted germacyclopent-3-enes

Formation of [Ar*Ge{CH2C(Me)C(Me)CH2}CH2C(Me)]2 (Ar* = C6H3-2,6-Trip2; Trip = C6H2-2,4,6-i-Pr3) via reaction of Ar*GeGeAr* with 2,3-dimethyl-1,3-butadiene: evidence for the existence of a germanium analogue of an alkyne

“…109.1°) and Ge-C bond distances that span the range 1.954( 5 pounds. 11,12 The angle at the Ge within the ring is 91.2(3)°w hich is also in good agreement with literature values [ca. 88-93°].…”

“…88-93°]. 11,12 The five-membered ring incorporating the Ge atom shows a puckered C s ring conformation. The degree of puckering, d, of germacyclopent-3-enes is defined by the angle between the plane containing the four carbon atoms of the ring and that containing Ge and the two adjacent ring carbons.…”

“…These angles depend on steric interactions of the other Ge substituents with the germacyclopent-3-ene ring which can have a large effect on d since there is only a small difference in energy between the puckered (C s ) and planar (C 2v ) ring conformation. 12 The formation of a 'bridged' product such as 2 on addition of a diene to germylenes was previously unknown. Initially, it was thought that a digermacyclohexadiene product would be obtained as illustrated in Scheme 1.…”

3,4-Dimethyl-1,1-bis[4-(trifluoromethyl)phenyl]-2,5-dihydro-1H-germole

“…Ge-C(aryl) bond distances, and the endocyclic C C bond distance of 1.345 (3) Å is quite similar to those found in cyclopentene derivatives (Guan et al, 2005). The bond distances and angles for (I) are comparable to those found in the considerably more structurally complex 1-germacyclopent-3-ene derivatives that have been previously characterized by crystallographic methods (Frö hlich et al, 1994;Fukaya et al, 2001;Lei et al, 1990Lei et al, , 1991Stender et al, 2002;Sugiyama et al, 2006).…”

Sequential Insertion of Formaldehyde and Carbon Monoxide into a Sulfide-Bridged Pd−Ge Bond Followed by Reductive Elimination To Form a [1,3,2]Oxathiagermolan-4-one

“…This bond-forming reaction could occur with the addition of a substrate molecule in whole or in part across the M−Ge moiety, with oxidation of the metal and/or oxidation of the germanium center, or with direct insertion into the M−Ge moiety with M−Ge bond cleavage. Numerous stable σ-bonded metal germylene complexes have been synthesized in the last few decades; − , however, comparatively fewer studies have emphasized the reactivity of the metal−germylene bond. ,,,,,− ,, …”