_P.-Powell-auth.-Principles-of-Organometallic-Chemistry-Springer-Netherlands-1988

General reactions of transition metal complexes
H2;1atm
W(C0)3L2 ~==~
16e
It forms yellow crystals which Iose hydrogen readily; it must therefore be kept
under hydrogen. The structure, determined at - 1 00°C by X-ray diffraction and
at room temperature by neutron diffraction, shows that direct H-H bonding is
retained. Moreover, in the n.m.r. spectra of the HD complex, coupling between 1 H
and 2 D nuclei is observed UHo = 3 3. 5 Hz; cf. HD(g), 43.2 Hz). Protonation of the
polyhydride IrH,L 2 (L = PCy ,) affords a cationic species in which two H 2
molecules are bonded to the metal centre.
Il' l . 1
+ MeCN [ +
IrH,L, ~ IrH 2 (H,j 2 L 2 ~ IrH,(MeCN),L,]
NEt 1
- - 11 z
(b) TETRAKIS(TRIPHENYLPHOSPHINE)PALLADIUM i\ND -PLATJNUM. Nickel,
palladium and platinum form neutra! tetrahedral phosphine complexes ML 4 (L
= PRJ They are prepared by reduction of metal salts in the presence of excess
ligand. The platinum and palladium complexes, M(PPh 3 ) 4 , have been most
thoroughly studied. They tend to dissociate in solution to three-coordinate and
even to two-coordinate species. The extent of dissociation depends on the steric
bulk ofthe phosphine (p.168). While no dissociation of Pd(PMe,) 4 can be detected
in solution by 31 P n.m.r., Pd(PPh 3 ) 4 forms Pd(PPh 3 ) 3 and a trace of Pd(PPh 3 ) 2 •
The very bulky ligand PPhBu~ affords a monomeric 14-electron complex
trons- [PdCL(COMe)L2]
Fig. 5.18 Some reactions ofPd(PPh,),. L=PPh,.
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