Synthesis and characterization of building blocks for tungsten-alkylidyne networks

Tungsten-alkylidyne polymers containing a W≡C fragment represent a relatively unexplored class of organometallic materials with potentially interesting properties and useful applications. Building blocks for new polymers containing a RC≡W core in their backbone were prepared, characterized, and spectroscopically studied to build a basic understanding of their fundamental structure-bonding relationships and electronic-structure properties.;Two types of building blocks for tungsten-alkylidyne donor-acceptor networks were prepared and characterized: those with extended aromatic cores (W(C-nap)(OBu t)3, W(C-anth)(OBut)3, and W(C-phen)(OBut)3) and those with multiple alkylidyne units around a single arene (1,3-C6H4{CW(OBut3}2 and 1,3,5-C6H3{CW(OBut3}3). In order to understand how these structural changes in the building blocks might affect the electronic structures of these complexes, the electronic absorption, emission, and emission lifetimes of the building blocks were studied and compared to their organic analogues.;The C6H6-n{CW(OBut) 3}n building blocks coordinate nitrogen bases (quinuclidene and 2,2'-bipyridine) similar to possible linkers. Additionally, two W(CR)(OBt)3 fragments can be linked together to form dimers {[W(CPh)(OBut) 3]2(mu-dabco), [W(CPh)(OBut) 3(eta1-4,4'-bpy)]2(mu-4,4 '-bpy), and [W(CPh)(OBut) 3]2(mu-pyz)}. The qualitative results of forming networks by combining the C6H6--n{CW(OBu t)3}n building blocks and linkers are discussed.;A separate class of building blocks was prepared via a convenient, high-yield method: to form W(CR)X3(dme) compounds from W(CR)(OBu t)3 triple-bond metathesis products. Tungsten-alkylidyne complexes of the type W(CR)X3(dme) (R = CMe3, n-Pr, Ph; X = Cl, Br; dme = 1,2-dimethoxyethane) are prepared in 75--85% yields (X = Cl: R = CMe3, 87%; R = n-Pr, 78%; R = Ph, 84% X = Br: R = Ph, 86%) by the addition of three equivalents of BX3 to a -78°C dry pentane solution of W(CR)(OBu t)3 and excess dme.