Coordination complexes of acetylenic phosphines and diphosphines

Reactions of (Me2C)(Me2Si)[(η5‐C5H3)­Mo(CO)3]2 with Phosphanylalkynes: Rearrangement of Phosphanylalkynes into Phosphido‐Substituted Vinylidenyl Ligands by Cleavage of the P–C(alkyne) Bond and Formation of a P–C(alkene) Bond

“…Signals appear at δ = 19.95 ppm for 2 and δ = 27.71 ppm for 4, which are both significantly downfield shifted in comparison to the signal of Ph 2 PCϵCPh (δ = -33.50 ppm). [13] It was reported that phosphanylalkyne itself [14] and phosphanylalkyne-bridged metal complexes such as Co 2 (CO) 6 -(µ-Ph 2 PCϵCt-Bu) [15] and (µ-Ph 2 PCH 2 PPh 2 )Co 2 (CO) 4 (µ-Ph 2 PCϵCR) (R = Ph, t-Bu, and Ph 2 P) [16] could be oxidized to their oxide partly during chromatography. The signal in the 31 P{ 1 H} NMR spectrum of the phosphanylalkynebridged metal complex is also shifted upfield relative to that of its oxide, for instance, δ = 6.8 ppm for (µ-Ph 2 PCH 2 PPh 2 )-Co 2 (CO) 4 (µ-Ph 2 PCϵCPh) versus δ = 28.4 ppm for its oxide.…”

Rhenium carbonyl compounds with (diphenyl)phosphinoalkynes and a sterically hindered phosphinoalkyne

“…The complex [NEt 4 ] 2 [ReBr 3 (CO) 3 ] [27a] and the acetylenic phosphines Ph 2 PC"CR {R = p-tolyl, Ph and t Bu} [37] were prepared by published procedures.…”

“…The phosphine (o-tolyl) 2 PC"CPh was prepared by using a similar procedure to that reported for Ph 2 PC"CR [37]. To a solution of phenylacetylene (0.45 mL, 4 mmol) in diethyl ether (20 mL) maintained at À78°C was dropwise added under stirring a solution of butyllithium (2.5 mL, 1.6 M in hexane; 4 mmol) in diethyl ether (20 mL).…”

Bis(acetylacetonato)ruthenium(ii) complexes containing alkynyldiphenylphosphines. Formation and redox behaviour of [Ru(acac)2(Ph2PCCR)2] (R = H, Me, Ph) complexes and the binuclear complex cis-[{Ru(acac)2}2(µ-Ph2PCCPPh2)}2]

“…Since the potentials for the stepwise oxidation of cis-6 differ by more than 250 mV, 56 the difference of E 1/2 values obtained from cyclic voltammetry or ac voltammetry can be related to the comproportionation constant K c , as shown in eqn (1). The derived value of ca.…”

“…Bis(diphenylphosphino)acetylene (dppa), Ph 2 PC≡CPPh 2 , behaves mainly as either a monodentate (j-P) or a bridging bidentate (l 2 -P) P-donor, 2,23-32 although a few examples of coordination via the alkyne function have also been established. 1,20,[33][34][35] In the l 2 -mode, dppa has been widely used to link metal complexes or clusters, but only a few studies of electronic communication between redox-active centres bridged by dppa have been reported. [36][37][38] We have shown that the alkene ligands of cis-[Ru(acac) 2 (g 2alkene) 2 ] [alkene = ethylene (1), cyclooctene (2); acac = 2,4pentadionato] are easily displaced by ligands (L), such as tertiary phosphines, phosphites, pyridine or tert-butyl isocyanide, to give trans-[Ru(acac) 2 L 2 ] as the kinetic products, which then usually isomerise to the more stable cis-products on heating.…”