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Reaction of the ethylene hydride complex trans-[(dmpe) MnH(C H )] (1) with Et SiH at 20 °C afforded the silylene hydride [(dmpe) MnH(=SiEt )] (2 a) as the trans-isomer. By contrast, reaction of 1 with Ph SiH at 60 °C afforded [(dmpe) MnH(=SiPh )] (2 b) as a mixture of the cis (major) and trans (minor) isomers, featuring a Mn-H-Si interaction in the former. The reaction to form 2 b also yielded [(dmpe) MnH (SiHPh )] (3 b); [(dmpe) MnH (SiHR )] (R=Et (3 a) and Ph (3 b)) were accessed cleanly by reaction of 2 a and 2 b with H , and the analogous reactions with D afforded [(dmpe) MnD (SiHR )] exclusively. Both 2 a and 2 b engaged in unique reactivity with ethylene, generating the silene hydride complexes cis-[(dmpe) MnH(R Si=CHMe)] (R=Et (4 a), Ph (4 b)). Compounds trans-2 a, cis-2 b, 3 b, and 4 b were crystallographically characterized, and bonding in 2 a, 2 b, 4 a, and 4 b was probed computationally.

Reaction of 4,5-bis(2,4,6-triisopropylanilino)-2,7-di-tert-butyl-9,9-dimethylxanthene (H 2 XN 2 ) with [Zr-(NMe 2 ) 4 ], followed by crystallization from O(SiMe 3 ) 2 , yielded [(XN 2 )Zr(NMe 2 ) 2 ]•{O(SiMe 3 ) 2 } 0.5 (1•{O(SiMe 3 ) 2 } 0.5 ). The zirconium dimethyl complex [(XN 2 )ZrMe 2 ] (2) was subsequently accessed (a) by treatment of 1•(O(SiMe 3 ) 2 ) 0.5 with excess AlMe 3 or (b) via reaction of 1•(O(SiMe 3 ) 2 ) 0.5 with excess Me 3 SiCl, affording [(XN 2 )ZrCl 2 ] (3) followed by reaction of 3 with 2 equiv of MeLi. Reaction of [(XN 2 )ZrMe 2 ] (2) with one equiv of B(C 6 F 5 ) 3 or [CPh 3 ][B(C 6 F 5 ) 4 ] yielded cationic [(XN 2 )ZrMe][MeB(C 6 F 5 ) 3 ] (4) and [(XN 2 )ZrMe(arene)][B(C 6 F 5 ) 4 ] {arene = η 6 -benzene (5a), η 6 -toluene (5b), or bromobenzene (5c)}, respectively. Both 4 and 5b are active for ethylene polymerization under 1 atm of ethylene at 24 and 80 °C in toluene with activities ranging from 23.5−883 kg mol −1 atm −1 h −1 , yielding polymers with weight-average molecular weights (M w ) of 70,800−88,100 g mol −1 and polydispersities (M w /M n ) of 3.94−4.67.

Interconversions between manganese silylene and silene complexes are reported, including those involving the first spectroscopically observed silene complexes with an SiH substituent, and their involvement in ethylene hydrosilylation is discussed.

Wilkinson’s manganese­(I) ethylene hydride complex trans-[(dmpe)2MnH­(C2H4)] (1) reacts as a source of a low-coordinate manganese­(I) ethyl complex. This is illustrated in the reactivity of 1 toward a variety of reagents. Reactions of 1 with primary silanes RSiH3 (R = Ph, n Bu) at 60 °C afforded ethane and the disilyl hydride manganese complexes [(dmpe)2MnH­(SiH2R)2] (4a, R = Ph; 4b, R = n Bu). Additionally, reaction with H2 at 60 °C afforded ethane and the dihydrogen hydride complex [(dmpe)2MnH­(H2)] (5), which has previously been prepared by an alternate route. The proposed low-coordinate intermediate, [(dmpe)2MnEt], was not observed spectroscopically but could be trapped using isonitrile ligands; reaction of 1 with CNR (R = t Bu, o-xylyl) afforded the manganese­(I) ethyl complexes [(dmpe)2MnEt­(CNR)] (6a, R = t Bu; 6b, R = o-xylyl). Ethyl complex 6a did not react further with CN t Bu at 80 °C. In contrast, complex 6b reacted with excess o-xylyl isonitrile to form 1,1-insertion products, including the iminoacyl complex [(dmpe)­Mn­(CNXyl)3{C­(NXyl)­CEt­(NXyl)}] (7, Xyl = o-xylyl). Complexes 4a, 6a,b, and 7, as well as the previously reported 1 and 5, have been crystallographically characterized, and DFT calculations have been employed to probe the accessibility of cis ethylene hydride and ethyl isomers of 1.

Manganese silyl dihydride complexes [(dmpe) 2 MnH 2 (SiHR 2 )] {R = Ph (3a), R = Et (3b)} and [(dmpe) 2 MnH 2 (SiH 2 R)] {R = Ph (4a), R = n Bu (4b)} were generated by exposure of silylene hydride complexes [(dmpe) 2 MnH(=SiR 2 )] (1a: R = Ph, 1b: R = Et) and disilyl hydride complexes [(dmpe) 2 MnH(SiH 2 R) 2 ] (2a: R = Ph, 2b: R = n Bu), respectively, to H 2 at room temperature. In solution, 3a,b and 4a,b exist as an equilibrium mixture of a central isomer with a meridional H−Si−H arrangement of the silyl and hydride ligands {this isomer may be considered to contain an η 3 -coordinated silicate (H 2 SiR 3 − ) anion}, and a transHSi isomer with trans-disposed hydride and nonclassical hydrosilane ligands (the latter is the result of significant but incomplete hydrosilane oxidative addition). Additionally, DFT calculations indicate the thermodynamic accessibility of lateralH 2 and transH 2 isomers with cis-and trans-disposed silyl and dihydrogen ligands, respectively. Compounds 3a and 4a crystallized as the central isomer, whereas 4b crystallized as the transHSi isomer. Bonding in the central and transHSi isomers of 3a,b and 4a,b was further investigated through 29 Si_edited 1 H− 1 H COSY solution NMR experiments to determine both the sign and magnitude of J 29Si,1H coupling (negative and positive values of J 29Si,1H are indicative of dominant 1-and 2-bond coupling, respectively). These experiments afforded J 29Si,1H coupling constants of −47 Hz for η 3 -(H 2 SiR 3 ) in the central isomer of 3b (calcd −40 to −47 for 3a,b and 4a,b), −38 to −54 Hz for η 2 -(R 3 Si−H) in the transHSi isomer of 3a,b and 4a,b (calcd −26 to −47 Hz), and 5 to 9 Hz for the terminal manganese hydride ligand in the transHSi isomer of 3b and 4a,b (calcd 12−14 Hz for 3a,b and 4a,b), experimentally supporting the nonclassical nature of bonding in the central and transHSi isomers.Article pubs.acs.org/Organometallics

Figure 1. Uranium(III) and (IV) complexes bearing selenium-containing [N-

Reactions of trans-[(dmpe)₂MnH(C₂H₄)] with hydroboranes and phosphines afforded manganese(i) borohydride and hydride complexes; reaction pathways, structures and bonding are discussed.