The synthesis of a tin(II) 1,3-benzobis(thiophosphinoyl)methanediide complex and its reactions with aluminum compounds are reported. The reaction of the 1,3-benzodiphosphole disulfide [1,3-C 6H 4(PhP=S) 2CH 2] (4) with [Sn{N(SiMe 3) 2} 2] in refluxing toluene afforded the tin(II) 1,3- benzobis(thiophosphinoyl)methanediide [{μ-1,3-C 6H 4(PhP=S) 2C}Sn] 2 (5). The X-ray crystal structure of 5 shows that it has a 1,3-dimetallacyclobutane structure. The reaction of 5 with 1 equiv of AlCl 3 in CH 2Cl 2 afforded [1,3-C 6H 4(PhP=S) 2C(Sn){Sn(S=PPh) 2C(AlCl 3)-1,3-C 6H 4}] (6). The reaction proceeds via an insertion of a AlCl 3 molecule into one of the Sn-C bonds in 5. The reaction of 5 with 2 equiv of AlCl 3 in CH 2Cl 2 afforded[1,3-C 6H 4(PhP=S) 2C(Sn)(AlCl 3)] (7). The reaction appears to proceed via the formation of compound 6, which then undergoes an insertion with another AlCl 3 molecule to form compound 7. The transmetalation reaction of 5 with 2 equiv of AlMe 3 in CH 2Cl 2 afforded [1,3-C 6H 4(PhP=S) 2CAlMe] 2 (8), which contains a terminal C methanediide-Al bond. © 2012 American Chemical Society.