lab 5.2 Gather not working

#include <iostream>
#include <mpi.h>
#include <vector>

using namespace std;

typedef struct three_args_struct {
    int first;
    int second;
    int third;
} triplet;

void buildDerivedType(MPI_Datatype* mpi_triplet_type) {
    int nitems = 3;
    int block_lengths[3] = { 1, 1, 1 };
    MPI_Aint offsets[3];
    MPI_Datatype typelist[3] = { MPI_INT, MPI_INT, MPI_INT };

    offsets[0] = offsetof(triplet, first);
    offsets[1] = offsetof(triplet, second);
    offsets[2] = offsetof(triplet, third);

    MPI_Type_create_struct(nitems, block_lengths, offsets, typelist, mpi_triplet_type);
    MPI_Type_commit(mpi_triplet_type);
}

void initializeTriplet(triplet* triplet, int rank) {
    triplet->first = rank;
    triplet->second = rank * rank;
    triplet->third = rank * rank * rank;
}

int main(int argc, char* argv[]) {
    MPI_Init(&argc, &argv);
    double startTime = MPI_Wtime();

    int rank;
    int threads_count;

    MPI_Comm_size(MPI_COMM_WORLD, &threads_count);
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
    int side_threads_count = threads_count - 1;

    MPI_Comm newcomm;
    int color;
    color = rank % 3;
    MPI_Comm_split(MPI_COMM_WORLD, color, rank, &newcomm);
    int newsize;
    MPI_Comm_size(newcomm, &newsize);
    //cout << "newSize = " << newsize << endl;

    if (rank % 3 == 0) {
        triplet sendBuf;
        initializeTriplet(&sendBuf, rank);
        cout << rank << ". first = " << sendBuf.first << ", second = " << sendBuf.second << ", third = " << sendBuf.third << endl;

        MPI_Datatype* mpi_newtype = new MPI_Datatype;
        buildDerivedType(mpi_newtype);

        triplet* recvBuf = new triplet[newsize];
        MPI_Gather(&sendBuf, 1, *mpi_newtype, recvBuf, newsize, *mpi_newtype, 0, newcomm);

        if (rank == 0) {
            cout << "Printing received array: " << endl;
            for (int i = 0; i < newsize; i++) {
                cout << i * 3 << " structure: first = " << recvBuf[i].first << ", second = " << recvBuf[i].second << ", third = " << recvBuf[i].third << endl;
            }
        }
    }

    double endTime = MPI_Wtime();
    double elapsed = endTime - startTime;
    //cout << "Program runtime: " << elapsed << endl;
    MPI_Finalize();
}