Synthesis and Structures of Monomeric Divalent Germanium and Tin Compounds Containing a Bulky Diketiminato Ligand

Abstract

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.

Preparation and Structure of the First Germanium(II) Hydroxide: The Congener of an Unknown Low‐Valent Carbon Analogue

“…In addition, the monoanionic ligand in 3 might affect the vibrational frequency by means of its steric demand and bonding mode. The 1 H NMR spectrum shows the expected pattern for the bdiketiminato ligand [10] and a resonance for the hydroxide proton at high field (d = 1.54 ppm), which is in accordance with the chemical shift observed for the OH group in tBu 2 Ge(OH) 2 (d = 1.49 ppm). [13] Surprisingly, the resonance for the corresponding group of (FcN) 3 GeOH (FcN = CpFe{h 5 -C 5 H 3 (CH 2 NMe 2 )-2}) was found at d = 8.98 ppm.…”

“…The most common route to organogermanium hydroxides is through the hydrolysis of organohalogermanes, but they can be only isolated when the supporting ligand is bulky enough. [9] Here we report on the hydrolysis of the stable germanium(ii) chloride [HC{(CMe)(2,6-iPr 2 C 6 H 3 N)} 2 GeCl] (1), [10] with a slight excess of water and one equivalent of 1,3-dimesitylimidazol-2-ylidene [11] (2; Mes = 2,4,6-Me 3 C 6 H 2 ) in toluene at room temperature, which led to the formation of [HC{(CMe)(2,6-iPr 2 C 6 H 3 N)} 2 GeOH] (3) in good yield (Scheme 1). In contrast, conventional hydrolysis of 1 in the presence of an amine or in liquid ammonia was unsuccessful Scheme 1.…”

Stable Monomeric Germanium(II) and Tin(II) Compounds with Terminal Hydrides

“…[6,7] Treatment of 1 with LiAlH 4 or NaBH 4 did not afford the terminal germanium(ii) hydride, but rather, the four-coordinate adduct [{HC-A C H T U N G T R E N N U N G (CMeNAr) 2 }Ge(H)BH 3 ] was formed. Moreover, attempts to prepare a terminal tin(ii) hydride from 2 in reactions with reducing reagents such as NaBH 4 , KBH 4 , and KH were unsuccessful.…”

“…In the IR spectrum of 3, a strong absorption was observed at 1733 cm À1 , which can be attributed to the GeÀH stretching mode and compares well with that reported for Ar'(H)GeGe(H)Ar' [13] (1785 cm À1 ; Ar' = 2,6-Dipp 2 C 6 H 3 , Dipp = 2,6-iPr 2 C 6 H 3 ), but is found at a lower frequency than that for [{HCA C H T U N G T R E N N U N G (CMeNAr) 2 }Ge(H)BH 3 ] (1928 cm À1 ). [7] Hydride complexes of germanium(iv) show GeÀH absorptions in the range from 1953 to 2175 cm À1 .…”

Can N-heterocyclic germylenes behave as Lewis acids - is there another side to Meller germylenes?

“…This is probably reflected in the N-Ge bond lengths, the ß-diketiminates have somewhat shorter N-Ge bonds. However, since in all structurally determined molecules of the monoimino germylene type, both N-Ge bond lengths are identical within experimental error [31][32][33][34][35][36][37][38][39][40][41][42], this distinction between coordinative and covalent bonds is unfounded.…”