This compound is not listed in CSD database in an unsolvated form.

The only solvate listed in the database is a benzene solvate:

C72H60P4Pd, 0.5(C6H6),

V. G. Adrianov et al., Zh. Strukt. Khim. (Russ.) (J. Struct. Chem.)

vol 17 p 135 y 1976

Probably this compound does not crystallize easily from weakly-solvating solvents and powder diffraction would be needed to solve the structure of the unsolvated form.

EDIT:

and here is the English version:

http://link.springer.com/article/10.1007%2FBF00748404

Thanks.  Is there a CIF also available for this solvate?

The CIF is TTPPDB.cif and can be downloaded from the Cambridge CDC

It is only a feeling but I think this compound is probably tetrahedral. This feeling comes from an attempt when we tried to determine the X-ray structure of an analogous Pd(0) compound, Pd(BDPP)2 (BDPP = chiral 2,4-bis-(diphenylphosphino)pentane). A square planar structure was out of question, while with the tetrahedral we came very close to the solution. Probably, we did not play long enough with the chelate conformation then.

The structure is indeed tetrahedral, but the bonding details are incompatible with those proposed by the quantum chemistry establishment.

Article Crystal structure of tetrakis(triphenylphosphine)palladium(0)

Article A Highly Regioselective Cyanothiolation of Alkynes via Oxida...

The crystal structure of [Pd(Ph3P)4] is reported here:

Article Crystal structure of tetrakis(triphenylphosphine)palladium(0)