I don't post papers about early metals (not 1st row ones; 2nd and 3rd row), and I think this may even be the first one I am sharing here. If you follow Prof. Liddle's group, you are probably aware of their U=P, Th=P complexes. I think I posted the one about thorium recently if not both. Here, they expand the same chemistry to early transition metals to investigate the M-P bond. They were able to structurally characterize both a phosphanide and a phosphinidene. They found out that the Zr-P bond is also polarized just like actinide-P bonds, and even less covalent than those (DFT). I am actually not completely surprised that it is not much covalent.
If you look at Scheme 1, you will see that Zr-PH bond is drawn as a double bond. The distance is actually ~0.2 A larger than the sum of their covalent radii and there is an agostic interaction Zr-H (check the crystal structure). But they calculated the Mayer Bond order as 1.48 and assigned it as a double bond. Sometimes schemes are not enough to visualize what really is going on. Anyway, I like this gorup's work and try to read their work as much as possible.