Reactive E=C(pp)π-systems. XLII: Novel coordination compounds of 2-(Diisopropylamino)-1-phosphaethyne: [{η4-(iPr2NCP)2}Ni{η 2-(iPr2NCP)}], [(Ph3P)2Pt{η2-(iPr2NCP)}], and [Co2(CO)6{η2-μ2-(iPr 2NCP)}]

Article abstract of DOI:10.1002/zaac.19966220106

2-(Diisopropylamino)-phosphaethyne iPr₂N-C≡P (2) reacts with the Ni(0)-complexes [Ni(1,5-cyclooctadiene)₂] and [Ni(CO)₃(1-azabicyclo[2.2.2]octane)], respectively, to give the novel complex [{η⁴-(iPr₂NCP)₂}Ni{η ²-(iPr₂NCP)}] (5), with the 1,3-diphosphacyclobutadiene derivative and 2 (side-on) as π-ligands. The molecular structure of 5 determined by X-ray diffraction on single crystals proves the spin systems and rotational barriers deduced from NMR-data (¹H, ¹³C-, ³¹P). The PC distances of the four-membered ring of 1.817(2) and 1.818(2) A - as expected - are considerably longer than the PC bond of the η²-coordinated phosphaalkyne 2 [1.671(2) A]. - In the reactions of 2 with [(Ph₃P)₂Pt(C₂H₄)] or [Co₂(CO)₈] the ligand properties of 2 resemble those of alkynes affording the complexes [(Ph₃P)₂Pt{η²-(iPr₂NCP)}] (7) with side-on coordinated 2 and [Co2(CO)₆{η²-μ²-(iPr₂NCP)}] with 2 acting as a 4e donor bridge in quantitative yield. In attempts to prepare copper(I) complexes of the aminophosphaalkyne 2 by reaction with CuCl or CuI the only isolable product formed in reasonable amounts under the influence of air and moisture is the 1λ³, 3λ⁵-diphosphetene (iPr₂N)CPC(iPr₂N)PO₂ (10) (isolated yield: ca. 20%). The crystal structure analysis of 10 indicates a strong structural relationship to the diamino-2-phosphaallyl cation [MePC(iPr₂N)PC(iPr₂N)]⁺ (12), the 1,3-diphosphacyclobutadiene ligand (iPr₂NCP)₂ in the binuclear complex [{η¹, μ²-(iPr₂NCP)₂}Ni₂(CO) ₆] (3 a) as well as to the heterocycles (dme)₂LiOCPC[OLi(dme)₂]PE′₂ (E′ = S, 11a; E′ = Se, 11b) prepared by Becker et al. [11b, 35]. Johann Ambrosius Barth 1996.