Crystal Structures of cis-M(CO)_4[tBu_2Si(OPPh_2)_2] (M = Cr, Mo)

摘要

Silandiyldiphosphinit tBu_2Si(OPPh_2)_2 1 wurde dargestellt. 1 reagiert mit den Norbornadienkomplexen C_7H_8M(CO)_4 (M = Cr, Mo, W) zu sechsgliedrigen Chelaten des Typs cis-M(CO)_4[tBu_2Si(OPPh_2)_2] 2-4. Die Kristallstrukturen des Chromkomplexes Cr(CO)_4[tBuSi(OPPh_2)_2] 2 und des Molybdänkomplexes Mo(CO)_4[tBuSi(OPPh_2)_2] 3 wurden bestimmt. Beide kristallisieren triklin (Raumgruppe P1) mit den Zellkonstanten: (2) a = 1 093(3) pm, b = 1477(5) pm und c = 1 542(5) pm; α = 108.4(2)°, β = 103.87(11)° und γ = 104.57(10)°; U = 2.143(12)nm~3; Z = 2; (3) a = 1097.8(2)pm, b = 1483.7(2) pm und c = 1 554.3(2) pm; α = 108.10(1)°, β = 103.956(6)° und γ = 104.213(7)°; U = 2.1899(6) nm~3; Z = 2. Beide Komplexe bestehen aus diskreten, leicht ver drillten oktaedrischen Monomeren mit annähernd planaren Chelatringen. Im Gegensatz hierzu wurde bei den Röntgen-strukturanalysen verwandter Komplexe Konformationen ermittelt, die von Twistboot zu „Chaiselongue" variieren.%Silanediyldiphosphinite tBu_2Si(OPPh_2)_2 1 has been synthesised. 1 reacts with the norbornadiene complexes C_7H_8M(CO)_4 (M = Cr, Mo, W) to give six-membered chelate rings of the type cis-M(CO)_4[tBu_2Si(OPPh_2)_2] 2-4. The crystal structures of the chromium and molybdenum complexes cis-Cr(CO)_4[tBu_2Si(OPPh_2)_2] 2 and cis-Mo(CO)_4[tBu_2Si(OPPh_2)_2] 3 have been determined. Both complexes crystallise in the triclinic system (space group P1) with unit cell parameters: (2) a = 1093(3) pm, b = 1477(5) pm and c = 1542(5) pm; α = 108.4(2)°, β = 103.87(11)° and γ = 104.57(10)°; U = 2.143(12)nm~3; Z = 2; (3) a = 1097.8(2) pm, b = 1483.7(2) pm and c = 1 554.3(2) pm; α = 108.10(1)°, β = 103.956(6)° and γ = 104.213(7)°; U = 2.1899(6) nm~3; Z = 2. Both 2 and 3 con-sist of discrete, slightly distorted, octahedral monomers in which the six-membered chelate rings are essentially planar. In contrast, the conformations of the chelate rings found in crystal structures of analogous complexes vary from twist-boat to "chaise longue".