The first stable 3,1-germaphosphaallene Tip(t-Bu)GeCPAr

Versatile Stereoselective Cycloadditions between Heterocumulenes and Phosphagermaallene Tip(tBu)GeCPMes*: Experimental and Theoretical Investigations

“…Synthesis of phosphagermaallene 1: Phosphagermaallene 1 was synthesized as previously described [7] by the addition of a solution of tert-butyllithium in pentane (1.7 m, 0.6 mL) to a solution of fluorophosphagermapropene TipA C H T U N G T R E N N U N G (tBu)Ge(F)ÀC(Cl)=PMes* (0.676 g, 1 mmol) in diethyl ether (10 mL) cooled to À78 8C. A 31 P NMR spectroscopic analysis (d = www.chemeurj.org 249.9 ppm) showed the nearly quantitative formation of phosphagermaallene 1.…”

“…CÀH insertion with acetonitrile [11] and ene-reactions with compounds that present a slightly acidic hydrogen (acetophenone, [7] methyl vinyl ketone [9] ) have also been observed. But the phosphagermaallene 1 also behaves as a 1,3-dipole by reacting with acetylene dicarboxylate [12] and benzonitrile [11] through the entire Ge=C=P unit (Scheme 1).…”

“…Derivatives with two heavy elements of different groups (14 and 15) are worthy of additional interest due to the presence of two different heavy double bonds and of a lone pair at the E 15 atom with the possibility of complexation by transition metals. In this field, the transient phosphasilaallene > Si=C= PÀ [6a] and phosphagermaallene > Ge=C=PÀ [6b] have been evidenced by NMR spectroscopy and trapping reactions, and the stable phosphagermaallene Mes*P=C=GeA C H T U N G T R E N N U N G (tBu)Tip 1 (Tip = 2,4,6-triisopropylphenyl, Mes* = 2,4,6-tri-tert-butylphenyl), [7] has been isolated. The latter shows a surprising ambivalent chemical reactivity.…”

“…C double bond: [2+1] with sulfur, selenium, or tellurium; [8] [2+2] with aldehydes and ketones, [7] a-ethylenic aldehydes, [9] p-quinones, [10] and pivalonitrile; [11] and [2+4] with a-ethylenic ketones [9] (Scheme 1). CÀH insertion with acetonitrile [11] and ene-reactions with compounds that present a slightly acidic hydrogen (acetophenone, [7] methyl vinyl ketone [9] ) have also been observed.…”

Electronic Properties and Reactivity of an Isolable Phosphagermaheterocyclic Carbene

“…Syntheses of 4 and 5: To a solution of phosphagermaallene 1 [17] (1 mmol) in Et 2 O (20 mL) cooled to À80 8C was slowly added one equivalent of diphenylketene dissolved in Et 2 O (10 mL). The reaction was monitored by dynamic 1 H, 13 C, and 31 P NMR spectroscopy between À80 8C and room temperature.…”