Multimetallic Complexes Based on a Diphosphine-Dithiocarbamate “Janus” Ligand

The HCl salt of the aminodiphosphine ligand HN­(CH2C­H2PPh2)2 reacts with [M­(CO)4(pip)2] (M = Mo, W; pip = piperidine) to yield [M­{κ2-HN­(CH2­CH2PPh2)2}­(CO)4]. The molybdenum analogue readily loses a carbonyl ligand to form [Mo­{κ3-HN­(CH2CH2PPh2)2}­(CO)3], which was structurally characterized. The same ligand backbone is used to form the new bifunctional ligand, KS2CN­(CH2­CH2PPh2)2, which reacts with nickel and cobalt precursors to yield [Ni­{S2CN­(CH2CH2­PPh2)2}2] and [Co­{S2CN­(CH2CH2PPh2)2}3]. Addition of [AuCl­(tht)] (tht = tetrahydrothiophene) to [Ni­{S2CN­(CH2­CH2PPh2)2}2] leads to formation of the pentametallic complex, [Ni­{S2CN­(CH2CH2PPh2­AuCl)2}2]. In contrast, addition of [PdCl2(py)2] (py = pyridine) to [Ni­{S2CN­(CH2­CH2PPh2)2}2] does not lead to a trimetallic complex but instead yields the transmetalated cyclic compound [Pd­{S2CN­(CH2CH2PPh2)2}]2, which was structurally characterized. The same product is obtained directly from [PdCl2(py)2] and KS2CN­(CH2CH2PPh2)2. In contrast, the same reaction with [PtCl2(NCPh)2] yields the oligomer, [Pt­{S2CN­(CH2CH2­PPh2)2}]n. Reaction of KS2CN­(CH2CH2PPh2)2 with cis-[RuCl2(dppm)2] provides [Ru­{S2CN­(CH2CH2PPh2)2}­(dppm)2]+, which reacts with [AuCl­(tht)] to yield [Ru­{S2CN­(CH2CH2­PPh2AuCl)2}­(dppm)2]+. Addition of [M­(CO)4(pip)2] (M = Mo, W) to the same precursor leads to formation of the bimetallic compounds [(dppm)2Ru­{S2CN­(CH2CH2PPh2)2}­M­(CO)4]+, while treatment with [ReCl­(CO)5] yields [(dppm)2Ru­{S2CN­(CH2CH2PPh2)2}­ReCl­(CO)3]+. Reaction of KS2CN­(CH2­CH2PPh2)2 with [Os­(CHCHC6H4Me-4)­Cl­(CO)­(BTD)­(PPh3)2] (BTD = 2,1,3-benzothiadiazole) provides [Os­(CHCHC6H4Me-4)­{S2CN­(CH2C­H2PPh2)2}­(CO)­(PPh3)2], but reaction with the analogous ruthenium precursor fails to yield a clean product.