{4-t-Bu-2,6-[P(O)(O-i-Pr)2]2C6H2Sn}2: An Intramolecularly Coordinated Organotin(I) Compound with a Sn–Sn Single Bond, Its Disproportionation toward a Diorganostannylene and Elemental Tin, and Its Oxidation with PhI(OAc)2

Syntheses of the intramolecularly coordinated organotin(I) compound {4-t-Bu-2,6-[P(O)(O-i-Pr)2]2C6H2Sn}2 (2), which crystallized in two different pseudopolymorphs 2 and 2·C7H8, of the diorganostannylene {4-t-Bu-2,6-[P(O)(O-i-Pr)2]2C6H2}2Sn (3) and of the organotin(II) acetate 4-t-Bu-2,6-[P(O)(O-i-Pr)2]2C6H2SnOAc (4) are reported. The compounds were characterized by multinuclear NMR, IR (3 and 4), UV–vis spectroscopy (2), electrospray ionization mass spectrometry (3 and 4), and single-crystal X-ray diffraction analyses. Density functional theory calculations on compound 2 revealed the stabilizing effect of the intramolecular PO → Sn coordination.