An Acyclic Dimer of Cyclodiphosphazane {tBuHN(tBuNP)2OCH2}2Containing Alkoxo and Amido Functionalities: Synthesis, Derivatization, Bi- (PdII, RhI), and Tetranuclear (PdII, AuI, RhIAuI) Transition Metal Complexes

Abstract

Acyclic bis(cyclodiphosphazane) [(t)BuHN((t)BuNP)(2)OCH(2)](2) (2) containing alkoxo and amido functionalities was synthesized by reacting cis-[(t)BuHN((t)BuNP)(2)Cl] (1) with ethylene glycol and upon further treatment with 4 equiv of elemental sulfur or selenium affords the corresponding tetrachalcogenides [(t)BuHN((t)BuNPE)(2)OCH(2)](2) (3, E = S; 4, E = Se) in quantitative yield. The reaction of 2 with 2 equiv of elemental sulfur results in the oxidation of only the amido-phosphorus atoms to form the di(sulfide) derivative [(t)BuHN(S)P(mu-(t)BuN)POCH(2)](2) (5). The reaction of 2 with 2 equiv of [PdCl(eta(3)-C(3)H(5))](2) afforded the tetrametallic complex [{Pd(eta(3)-allyl)Cl}(4){(t)BuHN((t)BuNP)(2)OCH(2)}(2)] (7) containing four independent [PdCl(2)(eta(3)-C(3)H(5))] moieties each coordinated to a phosphorus atom. In contrast, the reaction between [Pd(PEt(3))Cl(2)](2) and 2 leads to the addition of two metal atoms with the formation of [{Pd(PEt(3))Cl}(2){(t)BuHN((t)BuNP)(2)OCH(2)}(2)] (8), in which alternating phosphorus atoms of the bis(cyclodiphosphazane) are coordinated to palladium. Interestingly, the palladium(II) atom coordinated to the phosphorus atom bearing the t-butylamino substituent adopts a trans geometry, whereas that coordinated to the phosphorus atom connected to the -OCH(2)CH(2)O- linker prefers a cis conformation. The reaction between 2 and [Rh(COD)Cl](2) produces exclusively the bimetallic complex [{Rh(COD)Cl}(2){(t)BuHN((t)BuNP)(2)OCH(2)}(2)] (6) irrespective of the stoichiometry of the reactants and the reaction conditions. In complex 6, only the alkoxo-phosphorus atoms are coordinated. However, complex 6 upon treatment with AuCl(SMe(2)) in a 1:2 ratio gives the heterometallic tetrasubstituted complex [{Rh(COD)Cl}(2)(AuCl)(2){(t)BuHN((t)BuNP)(2)OCH(2)}(2)] (10). The reaction between 4 equiv of AuCl(SMe(2)) and 2 resulted in the formation of a tetrametallic gold complex [(AuCl)(4){(t)BuHN((t)BuNP)(2)OCH(2)}(2)] (9). The crystal structures of 2-4 and 7-10 are reported.