Synthesis of the New Silanediyldiphosphinite tBu2Si(OPPh2)2 and its Reactions with the Norbornadiene Complexes C7H8M(CO)4 (M = Cr, Mo, W). Crystal Structures of cis‐M(CO)4[tBu2Si(OPPh2)2] (M = Cr, Mo)

Abstract

AbstractSilanediyldiphosphinite tBu2Si(OPPh2)2 1 has been synthesised. 1 reacts with the norbornadiene complexes C7H8M(CO)4 (M = Cr, Mo, W) to give six‐membered chelate rings of the type cis‐M(CO)4[tBu2Si(OPPh2)2] 2–4. The crystal structures of the chromium and molybdenum complexes cis‐Cr(CO)4[tBu2Si(OPPh2)2] 2 and cis‐Mo(CO)4[tBu2Si(OPPh2)2] 3 have been determined. Both complexes crystallise in the triclinic system (space group P1) with unit cell parameters: (2) a = 1 093(3) pm, b = 1 477(5) pm and c = 1 542(5) pm; α = 108.4(2)°, b̃ = 103.87(11)° and b̃ = 104.57(10)°; U = 2.143(12) nm3; Z = 2; (3) a = 1 097.8(2) pm, b = 1 483.7(2) pm and c = 1 554.3(2) pm; α = 108.10(1)°, b̃ = 103.956(6)° and γ = 104.213(7)°; U = 2.1899(6) nm3; Z = 2. Both 2 and 3 consist 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”.