Oxygen can be bonded with 180° bond angles in perovskite structures, such as silicate minerals formed deep in Earth's mantle (the perovskite form of calcium silicate has been identified at Earth's surface by being trapped under internal pressure in diamonds). Such minerals have octahedrally coordinated silicon atoms connected by linearly two-coordinate oxygens, with the empirical formula $\ce{MSiO3}$.

Since the silicon in this silicate-perovskite structure is a $p$-block element and yet octahedrally coordinated, the covalent bonds to it are shared over multiple atoms and thus each silicon-oxygen linkage is partially ionic (cf. $\ce{SF6}$).

Oxygen can be bonded with 180° bond angles in perovskite structures, such as silicate minerals formed deep in Earth's mantle (the perovskite form of calcium silicate has been identified at Earth's surface by being trapped under internal pressure in diamonds). Such minerals have octahedrally coordinated silicon atoms connected by linearly two-coordinate oxygens, with the empirical formula $\ce{MSiO3}$. The calcium silicate compound referred to above has the structure given below (red = oxygen, black = silicon, blue = calcium)[Source]:

Since the silicon in this silicate-perovskite structure is a $p$-block element and yet octahedrally coordinated, the covalent bonds to it are shared over multiple atoms and thus each silicon-oxygen linkage is partially ionic (cf. $\ce{SF6}$).