Coordination properties of aminophosphine with first row transition metal nitrosyl complexes.

Abstract

The synthesis of the new thermolabile ironnitrosylhydride complex FeH(NO)(CO)(dppf) is reported. (dppf = 1,1$\sp\prime$-bisdiphenyl phosphino-ferrocene). The facile decomposition of FeH(NO)(CO)(dppf) is interpreted in terms of a homolysis of the Fe-H bond and of a nitrosyl transfer reaction. The synthesis of the structurally characterized iron complex Fe(O=PPh$\sb2$(2-Py))$\sb3\sp2\sp+\cdot$2BF$\sb4\sp-$, by the reaction of Fe(NO)$\sb2$(THF)$\sb2\sp+$ with PPh$\sb2$(2-Py) is described. The proposed mechanism for the formation of Fe(O=PPh$\sb2$(2-Py))$\sb3\sp2\sp+\cdot$2BF$\sb4\sp-$ involves a combination of disproportionation and oxygen transfer reactions. This dipositive iron complex is the first example of a first row transition metal chelated by the oxide of diphenyl(2-pyridyl)phosphines. The synthesis and the reactivity of the cobaltdinitrosyl monometallic Co(NO$\sb2$(PPh$\sb2(2$-Py))$\sb2\sp+\cdot$BF$\sb4\sp-$, Co(NO)$\sb2$(Py)$\sb2\sp+\cdot$BF$\sb4\sp-$, Co(NO)$\sb2$(Py)$\sb2\sp+\cdot$BPh$\sb4\sp-$ and bimetallic Co$\sb2$(NO)$\sb3$(PPh$\sb2$(2-Py))$\sb2\sp+$ -BPh$\sb4\sp-$ complexes are reported. The single crystal X-ray diffraction study of Co(NO)$\sb2$(PPh$\sb2$(2-Py))$\sb2\sp+$BF$\sb4\sp-$ shows that the aminophosphine ligands are co-ordinated through their P-donor sites. In solution, Co(NO)$\sb2$(Py)$\sb2\sp+$BF$\sb4\sp-$ was stable whereas, Co(NO)$\sb2$(Py)$\sb2\sp+$BPh$\sb4\sp-$ decomposed rapidly. The structural study of Co(NO)$\sb2$(Py)$\sb2\sp+$BF$\sb4\sp-$ has led to the proposal of a new theoretical model in which the non-bonded repulsions between the NO and L ligands of the M(NO)(L) moieties provide the most influential factor for fixing the value of the (O)N-M-N(O) angle. The structurally characterized Co$\sb2$(NO)$\sb3$(PPh$\sb2$(2-Py))$\sb2\sp+$ -BPh$\sb4\sp-$ complex is the first example of a bimetallic containing two metal-metal bonded first row transition metals with diphenyl(2-pyridyl)phosphine as a bridging ligand. It is also the first example of a Co$\sb2$(NO)$\sb3\sp+$ bimetallic core stabilized by two diphenyl(2-pyridyl)phosphine ligands coordinated by the P and N donor sites of the ligands arranged in a head-to-head fashion.