SYNTHESIS AND CHARACTERIZATION OF HETEROB IMETALLIC BIS(TRIMETHYLSILYL)PHOSPHANIDES OF BARIUM AND TIN

The reaction of barium bis[bis(trimethylsilyl)amide] with one equivale nt of bis(trimethylsilyl)phosphane in 1,2-dimethoxyethane (dme) yields the heteroleptic dimeric (dme)barium bis (trimethylsilyl)amide bis (t rimethylsilyl)phosphanide. This colorless compound crystallizes in the monoclinic space group P2(1)/n with a=1259.1(3), b=1822.7(4), c= 1516 .1(3) pm, beta=110.54(3)degrees and Z=4. The central moiety of the cen trosymmetric molecule is the planar Ba2P2-cycle with Ba-P-bond lengths of 329 and 334 pm. In the presence of bis [bis(trimethylsilyl)amino]s tannylene hetero-bimetallic bis(trimethylsilyl)phosphanides of tin(II) and barium are isolated. If the reaction of Ba[N(SiMe(3))(2)](2) and Sn[N(SiMe(3))(2)](2) in the molar ratio of 1:2 with six equivalents of HP(SiMe(3))(2) is performed in toluene, barium bis{tin(II)-tris[bis(t rimethylsilyl)phosphanide]} can be isolated. This compound crystallize s in the orthorhombic space group P2(1)2(1)2(1) with a=1265.1(1), b=22 90.1(3), c=2731.9(3) pm and Z=4. The anions {Sn[P(SiMe(3))(2)](3)}(-) bind as two-dentate ligands to the barium atom which shows the extraor dinary low coordination number of four. The addition of tetrahydrofura n (thf) to the above mentioned reaction solution leads to the eliminat ion of tris (trimethylsilyl)phosphane and the formation of thf complex es of barium hylsilyl)phosphanide-trimethylsilylphosphandiide}. The de rivative crystallizes from toluene in the monoclinic space group P2(1) /c with a=1301.9(2), b=2316.3(3), c= 3968.7(5) pm, beta=99.29(1)degree s and Z=8.