The signal depends on the other ligands.

For example: [RuCl(CO)(PPh3)2(C5H4NCOO)], where C5H4NCOO = 2-pyridinecarboxylate the 31P NMR signal is at 31.61 ppm.

Similar value of 31.41 is observed for [RuCl(CO)(PPh3)2(C9H6NO)], C9H6NO=8-quinolinol.

And:

[RuCl(CO)(PPh3)2(HBIm)], HBmI =2-(hydroxymethyl)benzimidazole  42.09 ppm 

[RuH(CO)(PPh3)2(1,10-phen)]Cl.H2O.(CH3)2O  1,10-phenanthroline 46.15 ppm

[RuCl2(HBO)(PPh3)2]  29.41

[RuCl(CO)(HBO)(PPh3)2]   37.05 HBO=2-(2-hydroxyphenyl)benzoxazole

[RuHCl(CO(PPh3)2(H2NPhBIm)]  H2NPhBIm= 2-aminophenylbenzimidazole 45.15

[RuH(N3)(CO)(PPh3)3]    40.11

[RuH(NCO)(CO)(PPh3)3]   40.48

[Ru(BIm-2-COO)2(PPh3)2].CH3OH.H2O BIm-2-COO=benzimidazolecarboxylate  48.50

[RuCl2(MeIm-2-COO)(PPh3)2]  MeIm-2-COO=1-methyl-1H-imidazole-2-carboxylate  38.42, 30.42

[Ru(NCS)2(MeIm)2(PPh3)2].CH3OH  MeIm=1-methylimidazole   46.91

[RuH(CO)(bzimpy)(PPh3)2]Cl∙CH3OH    42.35

[RuH(CO)(bzimpy)(PPh3)2]∙CH3OH  bzimpy=2,6-bis-(benzimidazol-2-yl)-pyridine   42.57

[RuHCl(CO)(PPh3)2(pyrim-4-Ph)]  pyrim-4-Ph=4-phenylpyrimidine   31.22

RuH(CO)(BimCOO)(PPh3)2]  BimCOO=benzimidazolecarboxylate   40.30 (d, J = 26.5 Hz), 37.48 (d, J = 26.2 Hz).

RuH(CO)(MeImCOO)(PPh3)2]CH3OH  41.10 (d, J = 26.8 Hz), 37.28 (d, J = 26.6 Hz).

[RuH(CO)((4-OH)BPA)(PPh3)2].CH3OH.H2O   (4-OH)BPA=5-(4-hydroxybenzoyl)pyrazine-2-carboxylic acid    43.83

[RuH(CO)((4-OH)BPAM)(PPh3)2].2CH3OH   (4-OH)BPAM=5-(4-hydroxybenzoyl)pyrazine-2-carboxamide   44.86), 44.57

If you have a complex containing PPh3 ligands, and you want to know if they are cis or trans, look at the coupling constants.  Trans coupling is much larger than cis.  If you suspect that your complex is cis, you can make the analogous complex using dppe (which will always be cis), and see if the spectra are similar.

The chemical shift of Ru-bound PPh3 ligands depends linearly on the Ru-P bond length. A chemical shift of about 10 ppm is associated with a long Ru-P bond of about 2.45 A. A chemical shift of about 95 ppm is associated with a short Ru-P bond of about 2.20 A. See Inorg Chem (1991) 30, 4617.

There may not be any P-P coupling if the two P atoms are chemically equivalent. However, splitting in the aryl region of the 13C NMR spectrum can be used to determine if two PPh3 are cis or trans.  See ref 16 of the above-mentioned paper.

Hi, I am also working on PPh3 based metal precursors. Ruthenium itself has many precursors like Ru(CO)Cl(PPh3) , Ru(p cymene )(Cl)(PPh3) and RuCl2(PPh3)3. Mostly the PPh3 signals are found at 31 ppm.