Reaction of the β-diketiminato lithium salt Li(OEt 2 )[HC(CMeNAr) 2 ] (Ar ) 2,6-i-Pr 2 C 6 H 3 ) with GeCl 2 ‚(dioxane) and SnCl 2 in diethyl ether provided the monomeric complexes [HC-(CMeNAr) 2 ]MCl (M ) Ge (2), Sn (3), respectively) with a three-coordinated metal center. The reductive dehalogenation reactions of 3 with C 8 K and LiAlH 4 afforded [HC(CMeNAr) 2 ] 2 Sn (7) and [HC(CMeNAr) 2 ]AlH 2 , respectively. The metathesis reactions of 3 with t-BuLi, AgSO 3 -CF 3 , and NaN 3 resulted in the formation of [HC(CMeNAr) 2 ]Sn(t-Bu) (4), [HC(CMeNAr) 2 ]-Sn(OSO 2 CF 3 ) (5), and [HC(CMeNAr) 2 ]SnN 3 (6), respectively. Compounds 2, 3, 5, and 7 were characterized by single-crystal X-ray structural analysis. The structures indicate that the β-diketiminato backbone is essentially planar and the metal centers reside in distortedtetrahedral environments with one vertex occupied by a lone pair of electrons. The bond angles at the metal center are in the range 85.2(8)-106.8(2)°, and the most acute angle is associated with the bite of the chelating ligand.

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.

The synthesis of the cyclodisilazane 1b in a ring-expansion reaction is the first example of a reductive insertion into the nitrogen-nitrogen single bond accompanied by migration of a phenyl group from the silicon to a nitrogen atom. An analogous ring expansion is observed in the synthesis of the cyclodisilazane 2b, which is the first reaction that involves migration of a hydrogen atom from a silicon to a nitrogen atom. A crystal structure is presented for compound 1b. Quantum chemical calculations support the experimental findings. The reaction enthalpy ∆ R H°(298 K) of the isomerization reaction converting the three-membered-ring (Me 3 -SiN) 2 SiF 2 (3a) into the cyclodisilazane Me 2 Si(NSiMe 3 NMe)SiF 2 (3b) is calculated to be -72.1 kcal mol -1 . The transition state and the unimolecular reaction mechanism are discussed in detail.

The synthesis of new compounds containing Al-Al, Ga-Ga, and In-In bonds, the 1-azaallyl ligand R (R ) [(Me 3 Si) 2 C(Ph)C(Me 3 Si)N]), and halide substituents is described. The gallium(III) compound RGaCl 2 (1) was prepared by reaction of GaCl 3 with RLi‚THF. The reduction of a mixture of RAlI 2 and RAlClI with potassium afforded [RIAl-AlClR] (2).[RGaCl] 2 (3) was synthesized by the reduction of RGaCl 2 with sodium/potassium alloy, while [RInBr] 2 (4) was prepared by reaction of RLi‚THF with indium(I) bromide. The molecular structures of 1, 2, 3, and 4 have been established by X-ray crystallography.

The fluorosilylhydroxylamine tBuSiF(Me)−ONH2 (2) is obtained in the reaction of tBuSiF(Me)−NHtBu (1) and HONH2·HCl. The reaction of tBuSiMe2−ONH2 with butyllithium leads to the formation of the bis(silyl)hydroxylamine tBuSiMe2−NH−O−SiF(Me)tBu (3). Depending on the bulkiness of the substituents and the solvent, lithium salts of N,O-bis(silyl)hydroxylamines crystallize as dimeric, trimeric, or tetrameric O-lithium-N,N-bis(silyl)hydroxylamides, e.g., [(tBuSiMe2)2N−OLi·THF]2, [(tBuSiMe2)2N−OLi]3 (4), and [tBuSiMe2(Me3Si)N−OLi]4 (6). Lithiation of tBuSiMe2ONHSiMe2 tBu in the presence of TMEDA leads to a cleavage of the N−O bond. The hexameric lithium silanolate (tBuSiMe2O−Li)6 (5) is obtained. Above 0 °C the lithium derivative of 3 (3a) reacts with LiF and the cyclic silylhydroxylamine (tBuSiMe-O−N−SiMe2 tBu)2 (7). In the reactions of 3a and 6 with F2SiMe2 and F3SiMe the first asymmetrical tris(silyl)hydroxylamines N,N-tBuSiMe2(FSi(Me)tBu)N−O−SiFMe2 (8), N,N-tBuSiMe2(SiMe3)N−O−SiFMe2 (9), N,N-tBuSiMe2(SiMe3)N−O−SiF2Me (10), and the bis((bis)(silyl)hydroxylamino)silane [N,N-tBuSiMe2(SiMe3)]2−O−SiFMe (11) are isolated. Chlorodimethylalane reacts with the trimeric O-lithium-N,N-bis(tert-butyldimethylsilyl)hydroxylamide to give LiCl and the four-membered ring system 2,4-bis-N,N-bis(tert-butyldimethylsilylhydroxylamide)-1-dimethylalano-3-lithio-2,4-dioxocyclobutane (12). Crystal structures of 4−7 and 12 are reported.