A monovalent aluminum monomer [{HC(CMeNAr)2}Al] was obtained by reduction of the corresponding aluminum(III) diiodide. The molecular structure shows a unique two‐coordinate aluminum center and a planar heterocyclic Al‐N‐C‐C‐C‐N six‐membered ring system (see picture). A nonbonded lone pair of electrons on the Al atom indicates the Lewis base character of the aluminum center. Ar=2,6‐iPr2C6H3.

Treatment of [{HC(CMeNAr) 2 }GeCl] (Ar ) 2,6-iPr 2 C 6 H 3 (1), 2,6-Me 2 C 6 H 3 (2)) with Me 3 -SnF in dichloromethane at room temperature afforded the corresponding fluoride [{HC-(CMeNAr) 2 }GeF] (Ar ) 2,6-iPr 2 C 6 H 3 (3), 2,6-Me 2 C 6 H 3 (4)), while with NaBH 4 in THF under reflux for 12 h gave the hydride [{HC(CMeNAr) 2 }GeH(BH 3 )] (Ar ) 2,6-iPr 2 C 6 H 3 ( 5), 2,6-Me 2 C 6 H 3 ( 6)). Reaction of 3 with Me 3 SiN 3 in toluene provided [{HC(CMeNAr) 2 }Ge(F)NSiMe 3 ] (Ar ) 2,6-iPr 2 C 6 H 3 ( 7)). The BH 3 in 5 can be removed with Me 3 P to afford [{HC(CMeNAr) 2 }-GeH] (Ar ) 2,6-iPr 2 C 6 H 3 (8)). Treatment of 5 with tBuLi in diethyl ether led to [{HC(C(CH 2 )-NAr)CMeNAr}Ge(H)BH 3 ]Li(Et 2 O) 3 (Ar ) 2,6-iPr 2 C 6 H 3 (9)), in which a hydrogen of one of the Me groups was eliminated, and this consequently resulted in the formation of a methylene group. Compounds 3-6 are the first examples of structurally characterized germanium(II) fluorides and hydrides. Single-crystal X-ray structural analyses indicate that compounds 3, 5, and 9 are monomeric and the germanium center resides in a trigonal-pyramidal environment in 3 and in distorted-tetrahedral environments in 5 and 9. † Dedicated to Professor Max Herberhold on the occasion of his 65th birthday.

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The pinewood nematode Bursaphelenchus xylophilus has caused severe damage to pine forests in large parts of the world [1-4]. Dispersal of this plant-parasitic nematode occurs when the nematode develops into the dispersal fourth larval stage (LIV) upon encountering its insect vector, the Monochamus pine sawyer beetle, inside an infected pine tree [5-9]. Here, we show that LIV formation in B. xylophilus is induced by C16 and C18 fatty acid ethyl esters (FAEEs), which are produced abundantly on the body surface of the vector beetle specifically during the late development pupal, emerging adult, and newly eclosed adult stages. The LIV can then enter the tracheal system of the adult beetle for dispersal to a new pine tree. Treatment of B. xylophilus with long-chain FAEEs, or the PI3 kinase inhibitor LY294002, promotes LIV formation, while Δ7-dafachronic acid blocks the effects of these chemicals, suggesting a conserved role for the insulin/IGF-1 and DAF-12 pathways in LIV formation. Our work provides a mechanism by which LIV formation in B. xylophilus is specifically coordinated with the life cycle of its vector beetle. Knowledge of the chemical signals that control the LIV developmental decision could be used to interfere with the dispersal of this plant-parasitic nematode.

Ein „Aluminiumcarben“: [{HC(CMeNAr)2}Al] zeigt ein planares heterocyclisches Al‐N‐C‐C‐C‐N‐Sechsringsystem mit einem zweifach koordinierten Aluminiumatom mit freiem Elektronenpaar (siehe Bild), wodurch die Verbindung den Charakter einer Lewis‐Base erhält. Hergestellt wird das Monomer durch Reduktion des entsprechenden Aluminium(III)‐diiodids.