The crystal structures of [Cu(PPh,),]CIO, (1 ) and [Ag(PPh3),]C1O4 (2) have been determined by single-crystal X-ray diffraction methods at 295 K, being refined by least-squares methods to residuals of 0.10 and 0.08 for 591 and 1 294 independent 'observed' reflections respectively. The two compounds are isomorphous (rhombohedral, space group R3, and Z = 2) with a = 19.02(2) A, a = 44.06(6)" and a = 19.085(5) A, a = 43.90(1)O respectively; the cation lies on a site of 3 symmetry, while the anion is disordered about a site of 3 symmetry. The metal-atom geometry is pseudo-tetrahedral [Cu-P = 2.60(1), 2.52(1) A; Ag-P = 2.668(5), 2.650(2) A, with all P-M-Pangles lying between 109.3 and 109.7'1. For the structure determination of [C~(PPh,)~(py),]Cl0, (3) obtained by the recrystallization of [Cu( PPh3),]CIO4 from pyridine (py), 2 843 'observed' reflections were refined to a residual of 0.052. Crystals are triclinic, space group P i , with a = 15.599(4), b = 13.413(4), c = 10.982(4) A, a = 79.51 (3), Q = 70.47(3), y = 86.03(3)", and Z = 2. Cu-P = 2.271 (4), 2.295(3) A and Cu-N = 2.1 02(7), 2.1 15(8) A in a pseudo-tetrahedral copper(1) environment, with P-Cu-P = 11 5.85(9)" and N-CU-N = 101.5(2)'. The 2,2'-bipyridyl (bipy) analogue [Cu( PPh3)2(bipy)]C104 (4) is monoclinic, space group P2,/c, with a = 10.21 0(3), b = 15.085(4), c = 28.455(9) A, /3 = 109.13(2)", and Z = 4. Cu-P = 2.246(3), 2.256(3) A and CU-N = 2.056(8), 2.1 13(9) A, with P-Cu-P = 125.4(1) and N-CU-N = 79.6(4)'. R was 0.081 for 2 605 reflections. [Cu( BH4) ( PPh3)2], by contrast, yie_lds a hemipyridine solvate, (5), on recrystallization from pyridine ; crystals are triclinic, space group P1 , with a = 12.849(6), b = 10.31 9(5), c = 13.61 8(6) A, a = 102.91 (4), p = 101.91 (4), y = 73.42(4)", and Z = 2. The structure was refined to a residual of 0.051 for 3 633 independent 'observed' reflections, and is isomorphous with the hemibenzene solvates of [CUX(PP~,)~] (X = CI or Br) and [AuCI(PPh,),].