Subvalent group 14 metal compounds: XV. Germanium and tin amides M(NR 2) 2 as ligands in carbonylchromium(0) chemistry. The crystal structure of the compounds cis-Cr (CO) 4{Sn(NR′ 2) 2} 2 M = Ge or Sn, R′ SiMe 3 or NR 2 = [formula omitted]2(CH 2) 3C Me 2

Abstract

The new crystalline complexes [Cr(CO) 5{M(NR 2) 2}] [NR 2  NCMe 2(CH 2) 3C Me 2 and M  Ge ( 1) or Sn ( 2)] and cis-[Cr(CO) 4{Sn(NR′ 2) 2} 2] (R′  SiMe 3) ( 3) are reported. Compounds 1 and 2 were prepared from [Cr(CO 5)(THF)] and M(NR 2) 2, while treatment of [Cr(CO) 6− n (NCMe) n ] [a ca. 12:6:1 mixture of n = 1, 2 ( cis), and 3, respectively] with an excess of Sn(NR′ 2) 2 yielded a 2:1 mixture of [Cr(CO) 5{Sn(NR′ 2) 2}] and the less pentane-soluble 3. Compounds 1–3 have been fully characterized. In crystalline 3, having l (<Cr>) 2.557(1) Å and l[CrC( trans to Sn)] shorter than l[CrC( cis to Sn)], there is significant departure from octahedral coordination around Cr [SnCrSn′ 101.37(3)°]; the NSnN′ bond angles [av. 105.0(2)° are essentially identical to that in crystalline Sn(NR′ 2) 2, although l(ŠnN>) in 3 is slightly shorter than in the free ligand.