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 [L 1 SnX]SnX 3 [L 1 =2,6-{(i-PrO) 2 (O)P} 2 C 5 H 3 N: 1, X=Cl; 2, X=Br], [L 2 SnCl]SnCl 3 [L 2 =2-{(i-PrO)Ph(O)P}-6-{(i-PrO) 2 (O)P}C 5 H 3 N: 3], [L 3 SnX]SnX 3 [L 3 =2,6-{MeO(O)C} 2 C 5 H 3 N: 4, X=Cl; 5, X=Br], [L 4 SnX]SnX 3 [L 4 =2,6-{Et 2 N(O)C} 2 C 5 H 3 N: 6, X=Cl; 7, X=Br]. These compounds were obtained by addition of SnX 2 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 [L 1 SnCl]SnCl 3 (1) with W(CO) 4 (thf) 2 afforded the tungsten tetracarbonyl complex [{L 1 SnCl}{SnCl 3 }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.