Synthesis and crystal structure of new polynuclear rhodium complexes formed by reaction of bis(η-ethylene)(η⁵-indenyl)rhodium with t-butylphospha-acetylene

Abstract

Treatment of bis(q-ethylene) (q5-indeny1)rhodium ( 1) or (cyclo-octa-l,5-diene) (q5-indeny1)rhodium(2) with t-butylphospha-acetylene (3) yields [q4-2,4-di (t-butyl) -1,3-diphosphacyciobutadiene] (q5-indeny1)rhodium (4) as the main product together with two other rhodium complexes ( 5) and ( 6) that contain derivatives of the new ligated systems 1,2,4,5-tetraphosphabenzenediyl and 1 -rhoda-2,5-diphosphacyclopentenediyl, respectively. Phosphorus-31, 'H, and 13C n.m.r. data are reported and are discussed in relation to the structures, which in the case of ( 5) and ( 6) were established by X-ray diffraction analyses. The n.m.r. spectra of (6) reveal restricted rotation of one of the indenyl groups.

Flexidentate Coordination Behavior and Chemical Non‐Innocence of a Bis(1,3‐Diphosphacyclobutadiene) Sandwich Anion

“…Althought he 1,2-isomer is more stable with small organic substituents, bulky groups such as R = tBu favor the formation of the 1,3isomer. [5,6] Our group developed anionic bis(1,3-diphosphacyclobutadiene) sandwich complexes [M(P 2 C 2 R 2 ) 2 ] À (M = Fe, Co;t ype A, Scheme1), [7] which were obtained from the reactiono fb is(an-thracene) metalates [M(h 4 -C 14 H 10 ) 2 ] À (M = Fe, Co;C 14 H 10 = anthracene) [8] with phosphaalkynes such as tBuÀCP, tPentÀCP, and AdÀCP( tBu = tert-butyl, tPent = tert-pentyl, Ad = adamantyl). [4] Since then, numerous 1,3diphosphacyclobutadiene complexes as well as some 1,2-diphosphacyclobutadiene complexes have been described.…”

Tetraphosphabenzenes Obtained via a Triphosphacyclobutadiene Intermediate

“…[37] Such rearrangements have also been observed for monophosphadewarbenzenes. [38] The Z-diphosphene of 8 shows a short P À P distance of 2.1047 (15) and angles of 96.93 (14) and 95. 16(14)8.…”

“…It is possible that the coordination sites of the two {W(CO) 5 } units coupled to subtle conformational differences lead to two rates of rearrangement from structures analogous to 1'. (17), W(1)-P(1) 2.6269 (11), W(1)-P(2) 2.6704(10), P1-W2 2.5807(11); C3-P3-C4 82.27 (19), P3-C4-P4 70.15 (15), C4-P1-P2 96.93 (14), C3-P2-P1 95.16 (14). Herein we have described the first reactivity of a triphosphacyclobutadiene intermediate.…”

“…[6][7][8][9] Diphosphacyclobutadiene and valence isomers of triphosphabenzene have been accessed through metal-mediated oligomerization of phosphaalkynes, [10][11][12] and two related reactions generate triphosphacyclobutadiene ligands -complexed to reducing metal centers. [13,14] There is also one example of a highly distorted P 4 (C t Bu) 2 ligand complexed between two Rh centers, [15] and a diradical valence isomer of a tetraphosphabenzene has been reported to contain multiple 1e  bonds. [16] Exploiting the chemistry of P 2 -derived cyclo-P 3 complexes, [17] we now describe neutral triphosphacyclobutadiene intermediates and isomers of tetraphosphabenzene that are stabilized only by mild W(CO) 5 substituents.…”

Use of 1,3‐diphosphacyclobutadiene complexes in the synthesis of mixed metal aggregates containing cobalt, rhodium, and platinum: Structure of a hexarhodium complex

“…coupling constant (7.3 Hz) indicates that the product might be a cis-disubstituted platinum complex; however, after 10 days, the 31P{1H} NMR spectrum of the reaction mixture showed a completely new pattern of resonances in which the small 2J(PP) ciscoupling was replaced with a large 2J(PP) coupling constant (>500 Hz), indicating the formation of a trans-isomer (see Figure 5). The new complex was identified as trans [PtC12(PEt3)Co(Cp")q4-(Bu'CP)2], 8 on the basis of its 31P{1H} NMR spectrum (see Table 4). …”