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Metal-mediated coupling of one isocyanide in cis-[PdCl2(CNR1)2] (R1 = C6H11 (Cy) 1, tBu 2, 2,6-Me2C6H3 (Xyl) 3, 2-Cl-6-MeC6H3 4) and various carbohydrazides R2CONHNH2 [R2 = Ph 5, 4-ClC6H4 6, 3-NO2C6H4 7, 4-NO2C6H4 8, 4-CH3C6H4 9, 3,4-(MeO)2C6H3 10, naphth-1-yl 11, fur-2-yl 12, 4-NO2C6H4CH2 13, Cy 14, 1-(4-fluorophenyl)-5-oxopyrrolidine-3-yl 15, (pyrrolidin-1-yl)C(O) 16, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propane-1-yl 17, EtNHC(O) 18] or sulfohydrazides R3SO2NHNH2 [R3 = Ph 19, 4-MeC6H4 20] led to a series of (hydrazido)(amino)carbene complexes cis-[PdCl2{ C (NHNHX) N(H)R1}(CNR1)]; X = COR2, SO2R3 (21–48, isolated yields 60–96%). All prepared species were characterized by elemental analyses (C, H, N), HR ESI+-MS, IR, 1H and 13C{1H} NMR spectroscopy, and by a single-crystal X-ray diffraction for 38. Complexes 21–48 demonstrated excellent activity as catalysts in copper-free Sonogashira coupling of aryl iodides and a variety of aromatic terminal alkynes. Catalytic system runs in environmentally benign EtOH ensuring product yields of up to 75–96% and TONs of up to 104. Mechanism of the copper-free Sonogashira catalytic cycle involving 21–48 as catalysts was proposed upon identification of key intermediates using HRESI-mass.

The metal-mediated coupling between cis-[PdCl2(CNR1)2] [R1 = cyclohexyl (Cy) 1, t-Bu 2, 2,6-Me2C6H3 (Xyl) 3, 2-Cl-6-MeC6H3 4] and hydrazones H2NN CR2R3 [R2, R3 = Ph 5; R2, R3 = C6H4(OMe-4) 6; R2/R3 = 9-fluorenyl 7; R2 = H, R3 = C6H4(OH-2) 8] provided carbene complexes cis-[PdCl2{C(N(H)N CR2R3) N(H)R1}(CNR1)] (9–24) in good (80–85%) yields. Complexes 9–24 showed high activity [yields up to 99%, and turnover numbers (TONs) up to 3.7 × 104] in the Sonogashira coupling of various aryl iodides with a range of substituted aromatic alkynes without the need of copper co-catalyst. The catalytic procedure runs at 80 °C for 1 h in EtOH using K2CO3 as a base. No formation of homocoupling or acetylene decomposition products was observed. Designed copper-free Sonogashira system can also run at room temperature giving target products with yields up to 87% and TONs up to 87.

Aminocarbene complexes cis-[PtCl2{ C (N(H)N = CR2R3)=N(H)R1}(CNR1)] (7–15) prepared via the nucleophilic addition of hydrazones H2N–N=CR2R3 [R2, R3 = Ph 4; R2/R3 = 9H-fluorenyl 5; R2 = H, R3 = 2-(OH)C6H4 6] to cis-[PtCl2(CNR1)2] [R1 = cyclohexyl (Cy) 1, 2,6-Me2C6H3 (Xyl) 2, 2-Cl-6-MeC6H3 3] were evaluated as catalysts for the hydrosilylation of terminal alkynes with trisubstituted silanes giving vinyl silanes. The optimized catalytic system runs at 80–100 °C in dry toluene for 3–6 h with a typical catalyst loading of 0.1 mol%. A range of substrates with different steric hindrance and activity (Et3SiH, Pr3SiH, iPr3SiH, and PhMe2SiH as silanes; PhC CH, tBuC CH, and 4-(tBu)C6H4C CH as alkynes) were successfully transformed into the target silylated products in 83–99% yields attesting the versatility of our catalytic system. Decreasing the catalysts loading to 10−3 mol% guaranteed the maximum TONs of 4.0 × 104 and TOFs of 1.7 × 103 (h−1) that were accomplished within 24 h of the reaction.