Intramolecularly O,N,O-Coordinated Tin(II) Salts: Syntheses, Structures, Cyclization, and Transition Metal Complexation.

We report the syntheses of tin(II) salts of the types [L1SnX]SnX3 [L1 = 2,6-{(i-PrO)2(O)P}2C5H3N: 1, X = Cl; 2, X = Br], [L2SnCl]SnCl3 [L2 = 2-{(i-PrO)Ph(O)P}-6-{(i-PrO)2(O)P}C5H3N: 3], [L3SnX]SnX3 [L3 = 2,6-{MeO(O)C}2C5H3N: 4, X = Cl; 5, X = Br], [L4SnX]SnX3[L4 = 2,6-{Et2N(O)C}2C5H3N: 6, X = Cl; 7, X = Br]. These compounds were obtained by addition of SnX2 to the corresponding ligand inducing autoionization of the respective tin(II) halide. The thermal stability of 1, 3, and 4 was elucidated, giving, under ester cleavage and cyclisation, the tin(II) derivatives 8-12. The reaction of [L1SnCl]SnCl3 (1) with W(CO)4(thf)2 afforded the tungsten tetracarbonyl complex [{L1SnCl}{SnCl3}W(CO)4] (13), representing the first example in which a tin(II) stannate anion and a tin(II) stannylium cation simultaneously coordinate to a transition metal centre. The compounds were characterized by single crystal X-ray diffraction analyses and in part by elemental analyses, IR and NMR spectroscopy, electrospray ionization mass spectrometry. DFT calculations accompany the experimental work.

N-Functionalized Ferrocenes: Subvalent Group†XIV Element Chlorides and tert-Butyllithium-Induced C-C Bond Cleavage under Mild Conditions.

The ferrocene derivative (η5 -Cp)Fe{η5 -C5 H3 -1-(ArNCH)-2-(CH2 NMe2 )} (1; Ar=2,6-iPr2 C6 H3 )) reacts diastereoselectively with LiR by carbolithiation and subsequent hydrolysis to give (η5 -Cp)Fe{η5 -C5 H3 -1-(ArHNCHR)-2-(CH2 NMe2 )} (3: R=tBu; 4: R=Ph; 5: R=Me) in high yields. For R=tBu, the organolithium derivative (η5 -Cp)Fe{η5 -C5 H3 -1-(ArLiNCHR)-2-(CH2 NMe2 )} (2) was isolated. Compound 2 reacts with GeCl2 ⋅dioxane and SnCl2 to give the metallylene amide chlorides (η5 -Cp)Fe{η5 -C5 H3 -1-(ArMNCHtBu)-2-(CH2 NMe2 )} 6 (M=GeCl) and 7 (M=SnCl), respectively, which each contain three stereogenic centers. The potential of 7 as a ligand in transition-metal chemistry is demonstrated by formation of its complex (η5 -Cp)Fe{η5 -C5 H3 -1-(ArMNCHtBu)-2-(CH2 NMe2 )} [9, M= Sn(Cl)W(CO)5 ]. Treatment of 3 with tert-butyllithium at room temperature causes an unprecedented carbon-carbon bond cleavage whereas under kinetic control, lithiation at the Cp-3 position takes place, which leads to the isolation of (η5 -Cp)Fe{η5 -C5 H3 -1-(ArHNCHtBu)-2-(CH2 NMe2 )-3-SiMe3 } (10).