The syntheses of the arylphosphonic esters 3-Br-5-tBu-1-{P(O)(OiPr) 2 }C 6 H 3 (1), 5-tBu-1,3-{P(O)(OiPr) 2 } 2 C 6 H 3 (2), of the heteroleptic intramolecularly coordinated organostannylenes [4-tBu-2,6-{P(O)(OiPr) 2 } 2 C 6 H 2 ]SnX (3, X = Cl; 4, X = Br; 5, X = I; 6, X = SPh), the organoplumbylene [4-tBu-2,6-{P(O)(OiPr) 2 } 2 C 6 H 2 ]PbCl (7), and the transition metal complex [4-tBu-2,6-{P(O)(OiPr) 2 } 2 C 6 H 2 ]Sn(Cl)-Cr(CO) 5 (8) are reported. The compounds were characterized by 1 H, 13 C, 31 P, 31 P MAS (3), 119 Sn, and 119 Sn MAS (3) NMR spectroscopy, electrospray ionization mass spectrometry (3), Mössbauer spectroscopy (3-5, 8) and single-crystal X-ray diffraction analyses (2, 3-5, 6-8). In contrast to its ethoxy-substituted analogue [4-tBu-2,6-{P(O)-(OEt) 2 } 2 C 6 H 2 ]SnCl, compound 3, like the thiophenolate derivative 6, is monomeric in solution as well as in the solid state. This difference is also manifested by the Mössbauer as well as solid state NMR spectroscopic data. On the other hand, the corresponding organoplumbylene 7 shows a similar chlorido-bridged polymeric structure as its ethoxy-

Syntheses of the intramolecularly coordinated organotin(I) compound {4-t-Bu-2,6-[P(O)(O-i-Pr)(2)](2)C(6)H(2)Sn}(2) (2), which crystallized in two different pseudopolymorphs 2 and 2·C(7)H(8), of the diorganostannylene {4-t-Bu-2,6-[P(O)(O-i-Pr)(2)](2)C(6)H(2)}(2)Sn (3) and of the organotin(II) acetate 4-t-Bu-2,6-[P(O)(O-i-Pr)(2)](2)C(6)H(2)SnOAc (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.

The syntheses of the intramolecularly coordinated organotin-substituted transition metal complexes [RSn{W(COand [RSn{W(CO) 3 Cp}-Cr(CO) 5 ] (5, R = 4-t-Bu-2,6-{P(O)(OEt) 2 } 2 C 6 H 2 ) are reported. The reaction of compound 2 with Ph 4 P + Br¯gave the benzoxaphosphastannole [1(P),3(Sn)-Sn[W(CO) 3 Cp] 2 OP(O)(Oi-Pr)-6-t-Bu-4-P(O)(Oi-Pr) 2 -C 6 H 2 ] (3). The compounds are characterized by 1 H, 13 C, 31 P, 119 Sn NMR and IR spectroscopy and, except for 3, by single crystal X-ray diffraction analysis. The experimental work is accompanied by DFT calculations.

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