[beethove]

What shape would atoms connected to two triply bonded C atom impose on the molecule that contains such a group?

GUESS: Triple C bond would be stiff at that point, but atoms connected to it by single bonds would be able to rotate about that stiff axis. So there'd be a stiff triple bond axis from which other parts rotate around.

[Symposium]

It's always linear. When I encounter some of these problems, I think of the shape of common organic chemicals that have a carbon-carbon triple bond, such as alkyne series hydrocarbons.

Take H-C≡C-H for example. It's a linear bond because there's no reason for the molecules to bend because of lone pair repulsion as described by the VSEPR theory. Similarly, any alkyne there is, is either linear or not in a stable configuration. Generally, at least.