Synthesis and Characterization of Free and Coordinated 1,2,3-Tripnictolide Anions

We have investigated the chemical reactivity of heptaatomic anionic clusters of the group 15 elements ([E 7 ] 3– /[HE 7 ] 2–, E = P, As) toward the symmetric and asymmetrically substituted alkynes diphenylacetylene and phenylacetylene. The results reported herein, alongside a previous report on the reactivity of such clusters toward acetylene, describe a versatile route by which to access otherwise elusive 1,2,3-tripnictolide anions of the general formula [E 3 C 2 RR′] − (R = R′ = H, E = P ( 1 ), As ( 2 ); R = R′ = C 6 H 5, E = P ( 3 ) As ( 4 ); R = H, R′ = C 6 H 5, E = P ( 5 ), As ( 6 )). These species can be isolated as [K(18-crown-6)] + or [K(2,2,2-crypt)] + salts. All anions were characterized by multielement NMR spectroscopy and electrospray mass spectrometry. In addition, single-crystal X-ray diffraction structures of the novel species [K(18-crown-6)(THF) 2 ][ 3 ], [K(2,2,2-crypt)][ 4 ]· x THF ( x = 0, 0.5), and [K(18-crown-6)THF][ 6 ] were also obtained. The chemical reactivity of these group 15 cyclopentadienyl analogues has been explored in a series of ligand displacement reactions with Mo(CO) 3 (L) 3 (L = CO, CH 3 CN) to yield the complex anions [(η 5 -E 3 C 2 H 2 )Mo(CO) 3 ] − (E = P ( 7 ), As ( 8 )), [{η 5 -E 3 C 2 (C 6 H 5 ) 2 }Mo(CO) 3 ] − (E = P ( 9 ), As ( 10 )), and [{η 5 -E 3 C 2 H(C 6 H 5 )}Mo(CO) 3 ] − (E = P ( 11 ), As ( 12 )).