The Preparation and Characterisation of Hetero‐ and Homobimetallic Complexes Containing Bridging Naphthalene‐1,8‐dithiolato Ligands

Homo‐ and heterobimetallic complexes of the form [(PPh 3 ) 2 (μ 2 ‐1,8‐S 2 ‐nap){ML n }] (in which (1,8‐S 2 ‐nap)=naphtho‐1,8‐dithiolate and {ML n }={PtCl 2 } ( 1 ), {PtClMe} ( 2 ), {PtClPh} ( 3 ), {PtMe 2 } ( 4 ), {PtIMe 3 } ( 5 ) and {Mo(CO) 4 } ( 6 )) were obtained by the addition of [PtCl 2 (NCPh) 2 ], [PtClMe(cod)] (cod=1,5‐cyclooctadiene), [PtClPh(cod)], [PtMe 2 (cod)], [{PtIMe 3 } 4 ] and [Mo(CO) 4 (nbd)] (nbd=norbornadiene), respectively, to [Pt(PPh 3 ) 2 (1,8‐S 2 ‐nap)]. Synthesis of cationic complexes was achieved by the addition of one or two equivalents of a halide abstractor, Ag[BF 4 ] or Ag[ClO 4 ], to [{Pt(μ‐Cl)(μ‐η 2 :η 1 ‐C 3 H 5 )} 4 ], [{Pd(μ‐Cl)(η 3 ‐C 3 H 5 )} 2 ], [{IrCl(μ‐Cl)(η 5 ‐C 5 Me 5 )} 2 ] (in which C 5 Me 5 =Cp*=1,2,3,4,5‐pentamethylcyclopentadienyl), [{RhCl(μ‐Cl)(η 5 ‐C 5 Me 5 )} 2 ], [PtCl 2 (PMe 2 Ph) 2 ] and [{Rh(μ‐Cl)(cod)} 2 ] to give the appropriate coordinatively unsaturated species that, upon treatment with [(PPh 3 ) 2 Pt(1,8‐S 2 ‐nap)], gave complexes of the form [(PPh 3 ) 2 (μ 2 ‐1,8‐S 2 ‐nap){ML n }][X] (in which {ML n }[X]={Pt(η 3 ‐C 3 H 5 )}[ClO 4 ] ( 7 ), {Pd(η 3 ‐C 3 H 5 )}[ClO 4 ] ( 8 ), {IrCl(η 5 ‐C 5 Me 5 )}[ClO 4 ] ( 9 ), {RhCl(η 5 ‐C 5 Me 5 )}[BF 4 ] ( 10 ), {Pt(PMe 2 Ph) 2 }[ClO 4 ] 2 ( 11 ), {Rh(cod)}[ClO 4 ] ( 12 ); the carbonyl complex {Rh(CO) 2 }[ClO 4 ] ( 13 ) was formed by bubbling gaseous CO through a solution of 12 . In all cases the naphtho‐1,8‐dithiolate ligand acts as a bridge between two metal centres to give a four‐membered PtMS 2 ring (M=transition metal). All compounds were characterised spectroscopically. The X‐ray structures of 5 , 6 , 7 , 8 , 10 and 12 reveal a binuclear PtMS 2 core with Pt⋅⋅⋅M distances ranging from 2.9630(8)–3.438(1) Å for 8 and 5 , respectively. The napS 2 mean plane is tilted with respect to the PtP 2 S 2 coordination plane, with dihedral angles in the range 49.7–76.1° and the degree of tilting being related to the Pt⋅⋅⋅M distance and the coordination number of M. The sum of the Pt(1)coordination plane/napS 2 angle, a, and the Pt(1)coordination plane/M(2)coordination plane angle, b, a+b, is close to 120° in nearly all cases. This suggests that electronic effects play a significant role in these binuclear systems.