Tuning the potential of redox-active diphosphine ligands based on the alkyne complexes [Tp*W(CO)L{η-C(PPh)}].

Eleven complexes with the general formula [Tp*W(CO)L{η-C(PPh)}] {Tp* = hydridotris(3,4,5-trimethylpyrazolyl)-borate, L = F, Cl, Br, I, MeS, PhS, pyCHS, CN and TfO; = 0 and L = CHCN and pyridine; = 1} have been synthesized and fully characterized. Depending on L, the oxidation process from W(II) to W(III) is detected between -0.28 and +0.

Metal/Metal Redox Isomerism Governed by Configuration.

A pair of diastereomeric dinuclear complexes, [Tp'(CO)BrW{μ-η -C,C'-κ -S,P-C (PPh )S}Ru(η -C H )(PPh )], in which W and Ru are bridged by a phosphinyl(thiolato)alkyne in a side-on carbon P,S-chelate coordination mode, were synthesized, separated and fully characterized. Even though the isomers are similar in their spectroscopic properties and redox potentials, the like-isomer is oxidized at W while the unlike-isomer is oxidized at Ru, which is proven by IR, NIR and EPR-spectroscopy supported by spectro-electrochemistry and computational methods. The second oxidation of the complexes was shown to take place at the metal left unaffected in the first redox step.

Sterically encumbered metalla-diphosphines: unlocking alkyne rotation by Pt coordination.

We present the synthesis and coordination chemistry of a series of W alkyne complexes with symmetric and asymmetric acetylene diphosphines. Chelate-like P,P'-coordination of PtCl cause a drastic potential change of the W centered oxidation proving intermetallic cooperativity. The choice of peripheric P-substituents has a measurable influence on the potential itself as well on the respective potential change upon coordination.

Synthesis and activation potential of an open shell diphosphine.

A paramagnetic W alkyne complex bearing free terminal diphenylphosphino groups at the side-on coordinated alkyne was synthesized using a stepwise template strategy. This moderately stable metal supported open shell diphosphine shows an unprecedented spontaneous splitting of nitric oxide providing a W-η-C{P(NH)Ph}{P(O)Ph} complex featuring an amino phosphonium and a phosphine oxide substituent.

Dual nucleophilic substitution at a W(ii) η(2)-coordinated diiodo acetylene leading to an amidinium carbyne complex.

The synthesis and reactivity of a W(ii) C2I2 complex towards various nucleophiles are described. Soft, aprotic nucleophiles like 4-dimethylaminopyridine (DMAP) lead to substitution of one CO at tungsten, whereas reaction with an excess of benzylamine results in a dual nucleophilic substitution at the alkyne moiety involving the rearrangement to a novel cationic amidinium carbyne complex.