Complexes of 3,3′‐Oxybis[(diphenylphosphino)methylbenzene] with Ni(II), Pd(II), Pt(II), Rh(I), and Ag(I). How Important is Backbone Rigidity in the Formation of trans ‐Spanning Bidenatate Chelates??

The bidentate diphosphine ligand, 3,3′‐oxybis[(dipenylphosphino)methylbenzene] ( 1 ) forms monomeric, trans ‐square‐planar complexes MX 2 ( 1 ) (M = Ni, Pd, Pt; X = Cl − , Br − I − , and, in part, N   3 − , NCS − , CN − , NO   3 − ) as well as Pt(H)Cl( 1 ), Pt(H)Br( 1 ), and RhCl(CO)( 1 ). Polymeric species have been observed with substitutionally inert metal centres: trans ‐[PtCl 2 ( 1 )] 2 and cis ‐[PtCl 2 ( 1 )] n (mean value of n ≈ 4–5) 31 P‐NMR, and selected IR and UV/VIS parameters are reported. Ligand 1 shows a marked preference for trans ‐spanning and monomeric chelate formation, despite its various degrees of freedom of internal rotation in the lignad backbone. The readily available ligand 1 as well as analogues with other donor atoms, therefore, appear useful in most potential applications of trans ‐spanning chelate ligands. The crystal structure of AgCl( 1 )·0.5 (CH 3 ) 2 CO·0.39 C 6 H 12 (space group C 2/ c , a = 21.02 Å, b = 14.57 Å, c = 24.79 Å, β = 99.77°, V = 7531.4 Å 3 , Z = 8) confirms the presence of three‐coordinate Ag( I ), with a coordination intermediate between a trigonal‐planar and a T‐shaped geometry (P‐Ag‐P = 145.61(8)°).