> glimpse(c1)
 num [1:654, 1:654] 0 25.811 21.364 0.927 4.069 ...
 - attr(*, "dimnames")=List of 2
  ..$ : chr [1:654] "1" "2" "3" "4" ...
  ..$ : chr [1:654] "1" "2" "3" "4" ...

> glimpse(c11)
 num [1:646, 1:646] 0 18.912 7.914 0.668 1.09 ...
 - attr(*, "dimnames")=List of 2
  ..$ : chr [1:646] "1" "2" "3" "4" ...
  ..$ : chr [1:646] "1" "2" "3" "4" ...

m <- matrix(runif(4*4),4,4)
m0 <- matrix(0,6,6)
m0[1:4,1:4]<-m # depends on where you want the correct data to exist inside m0

m0 <- matrix(0,6,6)
m0[3:6,1:4]<-m

m0 <- matrix(0,6,6)
m0[c(1,2,5,6),c(2,4,5,6)]<-m